ABSTRACT. KOHPRASERT, LALITA. The Interaction between Stickies and Polymer Additives on Unbleached Fiber. (Under the direction of Dr. John Heitmann.

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1 ABSTRACT KOHPRASERT, LALITA. The Interaction between Stickies and Polymer Additives on Unbleached Fiber. (Under the direction of Dr. John Heitmann.) This research is designed to study stickiness and agglomeration of tapioca starch and its derivatives together with the stickies in unbleached pulps. The extractives of pulps and stickies obtained by alcohol benzene solvent extraction are investigated by using thermal gravimetric analysis (TGA). The TGA method can prominently be operated is well suited for investigating the compositional analysis of deposits and pulps. Carbotac and Rosin size are used as references for the deposits based from hot melts and wood pitch. Different kinds of tapioca starches such as anionic, cationic and hydrophobic derivative added by octenyl succinic anhydride (OSA) were used in the experiments. Peel strength was tested by an Instron which demonstrates the bonding strength. The results show that the starch polymers are sticky even in the absence of stickies in the solutions. The force curve plots from the atomic force microscopy (AFM) display that the samples treated by using the tapioca starches give us less stickiness due to the decreased forces compared to the untreated samples. The testing on the Instron and the AFM give different measurement of adhesive force or stickiness; however this is believed to be because of the different mechanisms between used in these two methods.

2 The Interaction between Stickies and Polymer Additives on Unbleached Fiber by Lalita Kohprasert A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the Degree of Master of Science Forest Biomaterials Raleigh, North Carolina 2014 APPROVED BY: Dr. Lucian Lucia Committee Member Dr. Martin Hubbe Committee Member Dr. John Heitmann Chair of Advisory Committee

3 DEDICATION I dedicate this thesis to my parents, Dan and Tiptiya, who have supported me in everything since I was born. I would like to tell them that I will always love you forever. They are my inspiration encouraging me to chase my dream. I also dedicate this work to my younger brother, Weha, my younger sister, Waraporn, my relatives, and all of my friends in Thailand and around the world who were with me when I was downhill. I am appreciative to my boyfriend, Rapeepol, who makes me believe that every dream can come true and alive. The largest adventure is to live the life of our dreams and we can do it in this generation. I am thankful for myself that I did not give up the opportunity to come for study in the United States. It was not an easy situation for everyone to step out of a comfortable zone. I like joining the diverse opportunities and meeting new people and cultures here very much. All experiences in the United States will be lifelong experiences. ii

4 BIOGRAPHY I was born in Bangkok, the capital city of Thailand on September 25, I received my Bachelor Degree of Engineering in Chemical Engineering from King Mongkut s University of Technology North Bangkok (KMUTNB), Bangkok, Thailand in Afterwards, I worked as a production engineer in a kraft paper company for 2 years at Siam Kraft Industry Company (SKIC) in Ratchaburi, Thailand which was a subsidiary of Siam Cement Group or SCG. Then, I moved to a new position as a quality management engineer and worked in this position for 3 years at the same company. I then decided to ask for the scholarship from the company for studying in the United States. In July 2012, I came to North Carolina State University to pursue the Master Degree of Science for Forest Biomaterials in the College of Natural Resources under the direction of Dr. John Heitmann. iii

5 ACKNOWLEDGEMENTS I would like to express the deepest appreciation to my advisor, Professor Dr. John Heitmann, who has the excellent attitude, the invaluable guidance, the formative criticism, and the supportive encouragement throughout this project. He convincingly conveyed a spirit of adventure in regard to research. Without his guidance and continued help, this thesis would not have been possible. I would like to profoundly thank my committee members, Dr. Martin Hubbe and Dr. Lucian Lucia, who gave me useful comments and the helpful discussions. Appreciation is also extended to Dr. Sunkyu Park, Dr. Joel Pawlak, Dr. Orlando Rojas, Dr. Hou-Min Chang, Dr. Med Byrd and Dr. Perry Peralta for teaching me in the classes of Forest Biomaterials that enhance my knowledge for this work. I also acknowledge with appreciation to Siam Cement Group (SCG) for the financial support of my study for a master of science. I wish to thank Ms. Alicia Richards of Aquasol Corporation for providing tapioca starches, Sonoco Products Co. at Hartsville and Sonoco Recycling for giving me the pulps to use in this work. Finally, I thank my family, especially my mother Tiptiya Kohprasert, for giving me the best education and the encouraging motivation, wishing them happiness, full of joy, and healthy life. iv

6 TABLE OF CONTENTS LIST OF TABLES... vii LIST OF FIGURES ix INTRODUCTION... 1 LITERATURE REVIEW... 4 STICKINESS AND AGGLOMERATION BETWEEN STICKIES AND TAPIOCA STARCH POLYMERS ON UNBLEACHED PULP INTRODUCTION MATERIALS AND METHODS EXPERIMENTS AND RESULTS Solvent Extraction Experiments and Results Thermogravimetric Analysis (TGA) Experiments and Results Muffle Furnace Experiments and Results.. 54 Particle Size Experiments and Results Instron Tester Experiments and Results Atomic Force Microscopy (AFM) Data and Results DISCUSSION Comparison of Effective Solvent Reagents Decomposition Analysis of Extractives and Adhesives Ash and Particle Size Distribution The Effect of Tapioca Starch Polymers on Stickies.. 97 Peel Strength on the Mixture of Stickies and Starch Polymers v

7 The Treated and Untreated Surface Stickiness by AFM CONCLUSIONS. 102 SUGGESTIONS FOR FUTURE WORK REFERENCES CITED APPENDIX Appendix A - Moisture Contents Appendix B - The Ash from the Pulps, the Starches, and the Adhesives Appendix C - Average Particle Sizes of Stickies and Starches vi

8 LIST OF TABLES Table 1 Usage of paper and paperboard recovered in the U.S Table 2 Test methods for the determination of sticky contaminants in recycled fiber...18 Table 3 Comparison of characteristics, advantages and disadvantages of the evaluated Methods Table 4 Classification of Uncompressed Stickies Based on Removal Process.. 21 Table 5 General specification of native cassava starch.. 24 Table 6 Tapioca starch in comparison to other commercial starches Table 7 Degree of polymerization and molecular weight of commercial starches Table 8 The % extractives of DLK100%, DLK and stickies with the Hexanes reagent.. 44 Table 9 The % extractives of DLK 100%, DLK and stickies, the different ratios of DLK and SCP, SCP and stickies with the ethanol-benzene mixture reagent.. 45 Table 10 The ash from the pulps, the starches, and the adhesives at 400 o C and 900 o C. 54 Table 11 The ashes from the starches and the adhesives at 750 o C and 900 o C.. 55 Table 12 Average particle sizes of stickies in microns by Horiba Table 13 Average particle sizes of uncooked and cooked tapioca starches at 0.05% in microns by Horiba Table 14 Average particle sizes of cooked tapioca starch at 0.05% and Carbotac at 0.25% in microns by Horiba Table 15 The tip-sample interaction force (N) of stickies and tapioca starches by AFM...95 Table 16 The moisture content of DLK and SCP Table 17 The moisture content of starch polymers Table 18 The ash from the pulps, the starches, and the adhesives at 400 o C and 900 o C..111 Table 19 The ashes from the starches and the adhesives at 750 o C and 900 o C vii

9 Table 20 Average particle sizes of stickies by Horiba Table 21 Average particle sizes of uncooked tapioca starches at 0.05% by Horiba Table 22 Average particle sizes of cooked tapioca starches at 0.05% by Horiba Table 23 Average particle sizes of cooked tapioca starch at 0.05% and Carbotac at 0.25% by Horiba viii

10 LIST OF FIGURES Figure 1 Usage of Paper and paperboard recovered in the U.S Figure 2 The U.S. paper recovery rate.. 5 Figure 3 Recovery of OCC/Kraft papers for recycling in U.S Figure 4 Classification of stickies... 9 Figure 5 Contaminants frequently identified in paper machine deposits from recovered paper processing mills Figure 6 Overview of deposit sources in papermaking Figure 7 Relationship of filtrate tackiness to colloidal organics Figure 8 Chemical structure of part of a cationic starch molecule Figure 9 Diagram illustrating a typical ratio of sites on amphoteric starch Figure 10 Structure of OSA-modified starches Figure 11 Double Lined Kraft (DLK) from Sonoco Recycling Figure 12. The preparation process of DLK.. 33 Figure 13 Semi-Chemical Pulp from Sonoco at Hartsville, South Carolina Figure 14 The preparation process for SCP Figure 15 Carbotac by Lubrizol Advanced Materials, Inc., Ohio. 35 Figure 16 Paraffin wax by Fisher Inc Figure 17 Rosin gum by Acros Organics.. 36 Figure 18 Rosin powder, with diluent by Fisher Chemical.. 37 Figure 19 Rosin size, Champion 77 (Plasmine Technology) by Chemtrec.. 37 Figure 20 Tapioca starch by Aquasol Corporation ix

11 Figure 21 AquaBloc 252T by Aquasol Corporation.. 38 Figure 22 AquaFlocc330T by Aquasol Corporation Figure 23 Aquajel 65205TO by Aquasol Corporation Figure 24 Aquajel 73005TO by Aquasol Corporation Figure 25 Premium specialist cloth by Tork.. 40 Figure 26 Strip cutter for Tork cloth Figure 27 Microscope slides, 75 x 38 x 1.0 mm. by Fisher Scientific Figure 28 Microscope slides, 1 x 3 by Eisco Figure 29 DSC standard aluminum pans and lids by TA Instruments Figure 30 Comparison of the reagents with (a) Ethanol-Benzene mixture and (b) Hexanes in the Soxhlet Extraction apparatus over 8 Hours Figure 31 The extractives from the Ethanol-Benzene mixture reagent on (a) DLK, (b) DLK and stickies, (c) The different ratios of DLK and SCP, (d) SCP and stickies.. 45 Figure 32 Thermogravimetric Analysis Instrument (TGA) Figure 33 The liquid sample was placed on the DSC pan before loading on the platinum TGA pan Figure 34 The thermal decomposition analysis of adhesives on TGA. 48 Figure 35 The compositional analysis of pressure sensitive adhesives Figure 36 The TGA thermal decomposition analysis of pulp extractives with an ethanolbenzene mixture Figure 37 The compositional analysis of SCP and DLK ethanol-benzene extractives by TGA for different pulp blends. 51 Figure 38 The compositional analysis of natural tapioca starch and modified tapioca starch by TGA x

12 Figure 39 The compositional analysis of DLK ethanol-benzene extractives with different stickies compared to DLK100% by TGA. 52 Figure 40 The compositional analysis of SCP ethanol-benzene extractives with different stickies compared to SCP100% by TGA.. 53 Figure 41 The Muffle Furnace.. 54 Figure 42 The crucibles for testing ashes were composed of DLK, SCP, Carbotac, paraffin wax, rosin gum, rosin powder, rosin size, natural tapioca starch respectively, (a) the adhesive and pulp samples before ignition, (b) the ash at 400 o C, (c) the ash at 90 o C Figure 43 The crucibles for testing ashes contained Carbotac, paraffin wax, rosin gum, rosin powder, rosin size, natural tapioca starch respectively, (a) the adhesive samples before ignition, (b) the ashes at 750 o C, (c) the ashes at 900 o C Figure 44 The measurement principles of a laser scattering particle size distribution Analyzer Figure 45 Laser scattering particle size distribution analyzer, LA300, Horiba Figure 46 Particle Size Standards Figure 47 The peel strength testing by the Instron.. 61 Figure 48 The ghost view of the Instron instrument Figure 49 Instron tack tester model Figure 50 The extracts from DLK and SCP Figure 51 Peel strength of cooked tapioca starch and stickies with DI water. 64 Figure 52 Peel strength of stickies in (a) DLK extract and (b) SCP extract Figure 53 Cooked natural tapioca starch at 0.05% with Carbotac.. 66 Figure 54 Cooked cationic tapioca starch (Aquaflocc330T) mixed with Carbotac Figure 55 Pictures of the cooked anionic carboxymethyl OSA tapioca starch (Aquajel 65205TO) mixed with four different percentages of Carbotac xi

13 Figure 56 Pictures of the cooked cationic quaternary OSA tapioca starch (Aquajel 73005TO) mixed with four different percentages of Carbotac Figure 57 Peel strength of cooked tapioca starch and Carbotac at various percentages Figure 58 Pictures of shows the cooked cationic tapioca starch (Aquaflocc330T) mixed with four different percentages of rosin size (Champion77) from 0.25%, 0.50%, 0.75%, and 1.00% respectively Figure 59 Pictures of shows the cooked cationic quaternary OSA tapioca starch (Aquajel 73005TO) mixed with four different percentages of rosin size (Champion77) from 0.25%, 0.50%, 0.75%, and 1.00% respectively Figure 60 Cooked anionic tapioca starch (Aquabloc252T) mixed with rosin size.. 72 Figure 61 Pictures of shows the cooked anionic carboxymethyl OSA tapioca starch (Aquajel65205TO) mixed with four different percentages of rosin size (Champion77) from 0.25%, 0.50%, 0.75%, and 1.00% respectively.. 72 Figure 62 Peel strength of cooked tapioca starch and rosin size (Champion77) at the different percentages.. 73 Figure 63 Three commonly used techniques for AFM, (a) the contact mode, (b) the non-contact mode, and (c) the tapping mode.. 75 Figure 64. The force distance curve. The approach (red) and withdraw (blue) curves are shown on the right Figure 65 (a) The Atomic Force Microscope (AFM) analytical instrument, (b) The tip for the contact mode.. 76 Figure 66 The contact mode tip for testing on AFM Figure 67 The tapping mode tip for testing on AFM.. 77 Figure 68 The liquid samples were dried in the oven to produce the films Figure 69 The films were created on glass slides for testing on the AFM.. 79 Figure 70 The images of Carbotac at 0.25% filmed on the glass slide captured by the tapping mode on AFM Figure 71 The force curve of Carbotac at 0.25% by the contact mode on AFM. 82 xii

14 Figure 72 The images of films of Carbotac at 0.1% and uncooked tapioca starch at 0.1% captured by the tapping mode on AFM.. 83 Figure 73 The force curve of Carbotac at 0.25% and uncooked tapioca starch at 0.1% by the contact mode on AFM Figure 74 The images of films of Carbotac at 0.25% and cooked tapioca starch at 0.05% captured by the tapping mode on AFM.. 85 Figure 75 The force curve of Carbotac at 0.25% and cooked tapioca starch at 0.05% by the contact mode on AFM. There were two plots found from the tests.. 86 Figure 76 The force curve of Carbotac at 0.25% and cooked anionic tapioca starch (Aquabloc252T) at 0.05% by the contact mode on AFM Figure 77 The force curve of Carbotac at 0.25% and cooked cationic tapioca starch (Aquaflocc330T) at 0.05% by the contact mode on AFM Figure 78 The images of films of rosin size (Champion77) at 0.25% captured by the tapping mode on AFM Figure 79 The force curve of rosin size at 0.25% by the contact mode on AFM Figure 80 The images of rosin size (Champion77) at 0.25% and cooked tapioca starch at 0.05% filmed on the glass slide captured by the tapping mode on AFM Figure 81 The force curve of rosin size at 0.25% and cooked tapioca starch at 0.05% by the contact mode on AFM Figure 82 The force curve of rosin size at 0.25% and cooked anionic tapioca starch (Aquabloc252T) at 0.05% by the contact mode on AFM Figure 83 The force curve of rosin size at 0.25% and cooked cationic tapioca starch (Aquaflocc330T) at 0.05% by the contact mode on AFM Figure 84 The tip-sample system. D is the actual tip-sample distance, whereas Z is the distance between the sample and the cantilever rest position. These two distances differ because of the cantilever deflection δc and because of the sample deformation δs xiii

15 INTRODUCTION Old corrugated containers are a superb source of fiber for recycling because they can be baled and transported to the paper mill. They consist of baled corrugated containers having liners of either test liner or kraft. Recovered fiber that has been recycled many times suffers from a loss of strength, an accumulation of deposits, and the degeneration of fiber quality. Venditti et al. (2007) mentioned that one of the greatest challenges in paper recycling is the complete removal of adhesive contaminants referred to as stickies. This common difficulty can create many problems from the paper making process to the end users. There are many kinds of sticky materials that are mixed up in the paper bales. Several technologies are being developed continuously for advancing the efficiency of recycling mills to clean the incoming raw materials. Stickies are the wide class of deposits that result from synthetic and natural adhesive contaminants in wastepaper. Mills utilizing Old Corrugated Containers (OCC) typically face large problems with stickies. Stickies can be formed from the direct breakdown of adhesives in wastepaper (primary stickies) and/or from the interaction of chemicals (secondary stickies). The strategies used by mills to minimize stickies related problems include mechanical control, process control, and chemical control. The conditions of high temperature, mechanical agitation, and controlled processes causes stickies in a waste paper slurry to agglomerate into bigger particles. The clustered contaminants can be separated from the pulp slurry with a subsequent cleaning or screening system. However, there are still a lot of tiny particles that are hard to separate from the fiber slurry. 1

16 In recent years, many chemicals have been studied and developed to solve the problem of eliminating sticky contaminants on recycled paper. Improving the effectiveness of natural and synthetic chemicals for agglomerating small particles and decreasing tackiness is continuously researched to improve understanding of the fundamentals of chemical agglomeration processes and stickies removal systems. According to Kambe & Kamagata. (1969), the tackiness of stickies particles is greatly influenced by chemical interactions within the system Some synthetic and natural polymers have been shown to lessen the amount of stickies problems. From Huo (2002) s research, talc and cationic starches were found to affect stickies size, shape and tackiness after pulping. It was also found that poly- DADMAC and starches can prevent the agglomeration of stickies. However, it is unknown how the tackiness of the stickies correlates with the dosage of these polymers. Experiments should be conducted to determine the relationship between the amount of adsorbed cationic polymer on pressure sensitive adhesive particles/films and their tackiness by using a suitable tack tester. The use of starch polymers may be an efficient solution for reducing the tackiness and removing the contaminants in the paper making process. At North Carolina State University, many intensive studies have been performed to advance the removal processes in recycled paper. The purposes of this research are: 1. To enhance our understanding of recycled paper related to the removal of contaminants with respect to the quantity and chemical composition of 2

17 OCC and Semi-Chemical pulp in different furnish ratios. 2. To investigate the phenomenon of agglomeration and tackiness between various ionic tapioca starch polymers and stickies. 3. To research the possibility of using tapioca starch polymers and their derivatives to control stickies on OCC and Semi-Chemical pulp. 3

18 LITERATURE REVIEW According to The American Forest & Paper Association or AFPA (2012), the data for the year 2012 indicated that 31 percent of the paper and paperboard recovered in the U.S. went to produce containerboard (i.e., the material used for corrugated boxes) and 12 percent went to produce boxboard, which included folding boxes and gypsum wallboard facings. Exports of recovered paper to China and other nations in 2012 absorbed 41 percent of the paper collected for recycling in the U.S. as in Table 1 and Figure 1. Table 1. Usage of paper and paperboard recovered in the U.S (AFPA, 2012) Figure 1. Usage of paper and paperboard recovered in the U.S (AFPA, 2012) 4

19 In addition, AFPA (2012) reported that U.S. Paper recovery continued to be a success story, remaining strong and exceeding 60 percent each year since The recovered fiber market is a complex system in which supply, demand, and global economics all play a role in how much fiber is ultimately recovered. However, the two specific items that may have more strongly influenced the 2012 recovery rate were the recession in Europe and the economic slowdown in China. Exports to Western Europe were off 33 percent, while exports to Canada and Mexico declined 19.1 percent and 24.1 percent, respectively. Exports to China, the largest overseas customer for U.S. recovered paper, declined 0.8 percent in The 2012 U.S. recovery rate of 65.1 percent was the second highest on record, nearly doubling the rate of 33.5 percent in The U.S. recovered 51.1 million tons of paper for domestic recycling and export in 2012, which was up 76 percent relative to 1990 and 8 percent relative to 2000 as shown in Figure 2. Figure 2. The U.S. paper recovery rate (AFPA, 2012) 5

20 After increasing by 11.2% in 2010, the OCC/Kraft paper recovery rate remained stable between 2011 and 2012 at 91 percent, compared to 54.5 percent in 1993 as shown in Figure 3. Figure 3. Recovery of OCC/Kraft papers for recycling in U.S. (AFPA, 2012) Bittner (1994) stated that stickies were formed by many different materials and were considered to be one of the most troublesome contaminants in the paper industry. Stickies contaminants were not only cosmetically unappealing, but caused several functional problems for pulp and paper producers including buildup in felts, wires and drier cans of paper machines. These problems reduced production levels and paper quality. Other problems that could arise were web breaks and defects at the mill and at downstream converting and printing sites. According to the TIP from the Technical Association of the Pulp and Paper Industry or TAPPI (2011), many terms used to discuss stickies related problems 6

21 include: macro-stickies, micro-stickies, dispersed stickies, colloidal stickies, mini stickies, DISCO (dissolved and colloidal) stickies, primary stickies, secondary stickies, environmentally benign adhesives (EBA), recycle compatible adhesives (RCA), screenable stickies, removable stickies, depositable stickies, visible stickies, sub-visible stickies, and so on. From Oliver et al. (2000), the paper recycling industry has identified the soft and highly tacky PSAs (Pressure Sensitive Adhesives) as the most difficult stickies to remove from the recycling process. Problems Caused by the Recycling of Packaging Material Cathie (1994) mentioned that the deposition of stickies onto various parts of the paper machine equipment reduces paper machine productivity. We could generally break down the areas of production affected by stickies into the following categories. Stickies build up in forming fabrics and felts causing 'blinding', i.e., blocking of the pores and holes. This results in holes in the product, sheet breaks and reduced machine speeds, lowering productivity. Machines have to be shut down on a regular basis to solvent wash affected areas. Although they counteract the build-up of stickies, these solvents reduce felt and fabric life. Stickies can also adhere to drying cylinders, reducing heat transfer and energy utilization efficiency. Stickies appear as dirt spots in sheets and cause holes, thereby reducing product quality. Stickies which remain in the products may cause sheets or adjoining layers in a reel to stick together. As a result sheet breaks occur during printing or converting. The costs incurred by the wastepaper-using industry due to the stickies problem are difficult to assess accurately as many factors have to be considered, but they are obviously widespread and significant 7

22 Stickies Definition and Classification In paper recycling terminology defined by TIP (2011), stickies are primarily synthetic polymers arising from pressure sensitive adhesives (for example, styrene butadiene), hot melts (for example, polyvinyl acetate, PVA), binders used in coatings and inks (for example, styrene-butadiene, and polyacrylates), etc. Generally, a laboratory slotted screen is used to classify stickies. Stickies retained on the screen are termed macro-stickies while those passing through the screen are termed micro-stickies. The following image in Figure 4 illustreates classification of stickies. Macro-stickies: Retained on in (0.15 mm) or in (0.10 mm) or in (0.075 mm) laboratory slotted screen. Micro-stickies: Passing through in (0.15 mm) or in (0.10 mm) or in (0.075 mm) laboratory slotted screen. 8

23 Figure 4. Classification of stickies (TAPPI, 2011) Micro-stickies are further classified as follows: Suspended stickies, > 25 μm Dispersed stickies, 1 μm to 25 μm Colloidal stickies, < 1 μm Dissolved stickies The selection of 25 μm to distinguish between suspended and dispersed stickies is somewhat arbitrary. An alternative is to combine the two and call it suspended and 9

24 dispersed micro-stickies (> 1 μm). Micro-stickies could potentially agglomerate with fines and fillers due to accumulation in the water system and/or due to changes in ph, temperature, zeta potential, conductivity, etc. These agglomerates are termed secondary stickies. Types of Stickies Sarja (2007) classified organic deposits by origin into four main categories: adhesives, printing inks, coating binders, and wood extractives. The adhesives were usually, further, divided into pressure sensitive adhesives (PSAs) and hot melt adhesives (HMA). PSAs were tacky at all temperatures and HMA were applied molten to the substrates, and as the HMA cooled down, it adhered to the substrate. PSAs contain polybutadiene, polyisoprene, copolymers of styrene with butadiene or isoprene, polyacrylates, and copolymers of vinyl acetates and acrylates. The most common acrylic monomer used was 2-ethylhexyl acrylate, which provides the polymer with a low glass transition temperature. Many latex coating adhesives are copolymers of styrene and butadiene, or vinyl acetate copolymer. Figure 5 shows that the most common stickies substances (excluding wood extractives) are polyacrylates, polyvinyl acetate (PVAc), ethylene vinyl acetates (EVA) and styrene compounds. 10

25 Figure 5. Contaminants frequently identified in paper machine deposits from recovered paper processing mills (Sarja, 2007) Some contaminants always remain in the process, causing deposit problems in the mill. Negro et al. (n.d.) summarised the sources of different type of deposits in Figure 6. They stated that contamination problems were worse when the water system was closed, as there was an accumulation of contaminants and their concentration increased in the process water. This was due to the increase in suspended solids, the increase in dissolved and colloidal materials and the increase in temperature. 11

26 Figure 6. Overview of deposit sources in papermaking (Negro et al., n.d.) Wood Fibers as a Cause of Deposit Formation Hubbe et al. (2006) stated that wood itself contained a large variety of resinous substances. The chemical nature and concentration of these resinous substances depends heavily on the type of fiber (softwood, hardwood, and non-woody plants), the specific specie, and even the season of harvesting. Virgin fibers were typically the main source of natural and modified resinous materials present in papermaking process streams. The deposition tendency of pitch droplets composed of triglycerides and resin acids was strongly influenced by their relative solubility in water under ideal laboratory conditions. Deposition increased with increasing hydrophobic character. 12

27 Behavior of Stickies Stability of Stickies on Fiber Hutten et al. (1994) determined the strength of stickies attachment to fibers on bleached softwood kraft pulp by saturating the fiber with 19% by weight of PVAc (Polyvinyl Acetate), homopolymer applied from a methanol solution. The treated pulp was then dried at room temperature, blended in different ratios with untreated pulp, and processed through the Britt jar. The amount of PVAc in water did not change appreciably as the blends change, suggesting that the PVAc in the pulp did not readily transfer to water under the experimental conditions. Although the amount of fiber and PVAc increased in both water and fiber phases as the amount of PVAc increases, the ratio did not. This indicated that the distribution of PVAc between water and fiber was constant because the PVAc was strongly attached to the fiber. In conclusion, the presence of fiber tended to retard PVAc agglomeration. Once attached to fiber, PVAc was not easily removed. Attachment of Stickies to Fines Hutten et al. (1994) also explored the adsorption of stickies on bleached pulp beaten to different freenesses. Britt jar sorption measurements were made with PVAc. The fiber : water distribution coefficient (Kd) increased dramatically with decreasing freeness. The higher the Kd, the greater propensity of the stickies to attach to the fiber. The reason for this was that the fines were better filter in the low-freeness sheets, and the amount of material transferred to the water layer was greatly diminished. The PVAc and fines ratio in the aqueous phase tended to be much more constant in the result, 13

28 strongly indicating that the stickies present in the water were associated with fines, at least in the absence of surfactants and other chemicals. PVAc preferentially sorbs to fines. Tackiness Tackiness is a significant property for a lot of industrial materials. It has been studied by diverse methods and many investigators, but the conclusions often have not been adequately clear due to its complicated nature. Kambe & Kamagata (1969) gave us an interesting explanation of tackiness. The phenomena of tackiness might be roughly divided into three cases depending on the material concerned. First was the tackiness of rubbers or elastomers. In this case, tackiness meant that the material did not adhere to the other materials, but adheres to itself on application of a light pressure. Such a tackiness between similar materials was called the autohesion. Secondly, there was tackiness connected with a viscous liquid like a printing ink. On printing, the tackiness showed up as the resistance to separating the printing surface from the paper surface, when the ink remained on both surfaces as thin layers. The partition of the ink layer was caused by an abrupt fracture of the ink membrane. The ink flowed along the line of the weakest resistance, became a thin thread, and came to fracture with a weak force. Thirdly, tackiness was involved in pressure-sensitive adhesive tape on which was applied a resin layer having a moderate viscosity. Several detailed studies have also been carried out regarding this type of tackiness. Hayes (2011) reported another test to measure the tackiness of the filtrate which gave a visible response to the nature of the invisible colloidal stickies. A relationship was found between tackiness and colloidal organics as shown in Figure 7. 14

29 Samples with a higher than expected tackiness had been linked with runnability issues on the paper machine. TOC = Total Organic Carbon Figure 7. Relationship of filtrate tackiness to colloidal organics (Hayes, 2011) Hayes (2012) reported that the colloidal and dissolved organic content should be measured along with the tackiness and other common measurements for different pulping conditions to better understand the stickies and white pitch released. The study found that low consistency, longer pulping times and higher temperature would release more dissolved and colloidal organics and produce higher tackiness. Envelopes released more colloidal organics and had higher tackiness than seen with other recycle furnishes. Deposit control for recycled furnishes which used fixatives such as cationic polyamide, polyamine, and poly dadmac were found to be the least effective while minerals based 15

30 aluminum and silica, talc, nonionic surfactant dispersant and cyclodextrin detackifiers were more efficient. Coated paper tackiness was very dependent on the type of binder used and treatment options could be effective with certain types of fixatives, aluminum based inorganics and cyclodextrin detackifiers. Agglomeration Many chemical agglomeration processes have been developed to solve the problem of removing inks and other contaminants. Chen (1999) experimented with waste paper by heating to temperatures above the softening temperature of the thermoplastic ink. With the help of the added agglomeration promoting chemicals and adequate mixing, the thermoplastic ink particles agglomerate. These generally spherical agglomerates can be larger than 1 mm. in diameter. Upon cooling the mixture below the softening point of the toner, the agglomerates became hard and may be separated from the pulp by using conventional centrifugal cleaners or screens. With an agglomeration step, not only can the large specks of the ink be removed, but also other material, such as small plastic contaminants in the pulp may be removed in the same step. The agglomeration process can be carried out with common equipment such as a pulper followed by centrifugal cleaners or screens, so that a mill can retrofit a process without significant capital investment. Based on the chemicals used in different agglomeration systems, several studies can be classified as either dual- or single-chemical processes. For the dualchemical process category, chemical additives typically included a polymer and an agglomeration promoter, (i.e. a low molecular weight surfactant or hydrophobic material). The role of the polymer was to enhance the material properties of agglomerates 16

31 and to increase the total amount of surface area available for agglomeration. Polymers that were reported to be effective were polyacrylates, polyvinyl chloride, polyacrylic acid, and the copolymers of these materials. Chen (1999) completed a study on the mechanism of photocopied paper deinking with tall oil fatty acid (TOFA) and developed an effective deinking procedure for Mixed Office Waste (MOW) by using TOFA. The agglomeration deinking process should perhaps be conducted at a lower temperature when using TOFA because of its lower melting point when compared to that of 1-octadecamol. A lower pulping temperature will result in a lower energy cost. Also, it was recommended to investigate the strength properties and surface properties of recycled paper from the agglomeration deinking processes because the oily agglomeration agents may have an effect on these properties if absorbed onto the surface of recycled fibers. Test Methods for Tacky Deposits Hubbe et al. (2006) said that it could be difficult to achieve credible simulations of production problems by use of laboratory tests. During commercial-scale papermaking it is common for a wetted surface to be exposed to literally tons of materials, with intense flow conditions and elevated temperatures continuing without significant interruption for many days. Though a papermaking furnish often contained 1-5% of pitch or sticky materials, on a weight basis, the proportion of this material that ever became involved in deposits usually was quite small. However, even a very small amount of these materials, if deposited in a critical location, may be enough to require a shutdown of a paper 17

32 machine system. Ling, Hall & Walker (1993) reviewed the existing methods for determining the stickies content of a fiber slurry as shown in Table 2. Table 2. Test methods for the determination of sticky contaminants in recycled fiber Ling, Hall & Walker (1993) Sarja (2007) pointed out that some of the deposition methods were successful in showing the trend, while some of the methods did not detect the differences between the pulp mixtures. However, it was suspected that there was not very much micro-stickies, but mainly macro-stickies in the stickies-rich pulp to start with. Sitholé & Filion (2007) compared the characteristics, advantages, and disadvantages of the methods as shown in Table 3. 18

33 Table 3. Comparison of characteristics, advantages and disadvantages of the evaluated methods (Sitholé & Filion, 2007) 19

34 Control of Stickies Negro et al. (n.d.) suggested methods to avoid the problems caused by stickies using numerous mechanical and chemical stickies control and prevention systems. A classification of control methods for primary and secondary stickies was described as follows; Selection and inspection of raw materials. Mechanical methods : cleaning, screening, washing, thermal and/or mechanical dispersion, fractionation and dispersion. Chemical methods : adsorption, chemical dispersion, fixation, surface passivation, surface cleaning and flotation. Biotechnology methods : enzymatic treatment and biological treatment. Proper water circuit design and reject handling. Screening Haynes (2011) stated that a stickies cut-off of 75 microns was found to be important with respect to stickies behavior during a study comparing methods for measuring micro-stickies. Methods that did not fractionate or fractionated above 75 microns detected stickies that behaved in a similar manner as macro-stickies. The dissolved, colloidal, dispersed and suspended stickies below 75 microns behaved in a different manner. DeJong & Pescantin (2005) mentioned that stickies passed through the slotted screens can subsequently be removed by process equipment, which has been primarily designed to remove low density stickies such as reverse cleaners, or flotation cells as shown 20

35 in Table 4. A combination of screens, low density cleaning equipment, and flotation was able to remove 60 99% of the incoming stickies area depending upon the choice of equipment, operating conditions and the type of stickies in the waste paper furnish. Table 4. Classification of Uncompressed Stickies Based on Removal Process (DeJong & Pescantin, 2005) Flotation Sarja (2007) mentioned that flotation was very effective in removing stickies, especially micro-stickies. Ink was also very well removed in flotation processes with a similar or slightly lower efficiency than stickies. The good floatability of micro-stickies and ink was due to the same mechanism for removal. They were both hydrophobic and had optimal size distribution for flotation from a few micrometers up to about 100 μm. Enzymatic Treatment Doshi et al. (1999) analyzed the deposited stickies under a microscope and found fibers associated with each sticky. The attachment of fibers thus created a hairy sticky. From this observation, a cellulase enzyme was added to the slurry under the proper enzymatic conditions to help clean off the fibers before attempting to collect the micro- 21

36 stickies on the hydrophobic material. The results obtained from the cellulase enzyme treated slurry showed no micro-stickies present. This was an interesting result and needed further investigation. One explanation was that the surface characteristics of the stickies were altered by the enzyme and, therefore, had no affinity for the hydrophobic surface of the collecting media. Types of Additives Effective Against Deposits Hubbe et al. (2006) detailed that chemical antidotes to combat tacky deposits on paper machines were more diverse than the deposits themselves. These include adsorbent materials, multivalent cations, polyelectrolytes of various degrees of charge density and hydrophilic or lipophilic character, inorganic dispersants, surfactants, solvents, biocides, and enzymes. It is common for two or more such approaches to be applied simultaneously, often at different points in the papermaking process. Overall, there has been continual development of anti-deposit treatments, usually with a goal of decreasing the cost of first-quality paper production. Some newer developments were also motivated by a desire to minimize various environmental impacts. Polymeric Polysaccharides for Stickies Control There are a number of studies of synthetic and natural polymers for stickies control. Hubbe et al. (2006) reported that many of the chemical additives found to be effective for control of tacky deposits can be described as organic polymers. The effects of polymeric agents were greatly dependent on how these materials interact with surfaces. Huo (2002) focused on talc and cationic starches and found that there were some effects 22

37 on stickies. Moreover, Poly-DADMAC and starches were mentioned in the article that can decrease the agglomeration of stickies. Banerjee & Haynes (2008) studied Cyclodextrins (CDs) that are cyclic structures consisting of six to eight glucose units. The work showed that they could dramatically reduce the tack of stickies and also inhibit the tendency of micro-stickies to form films, making them more wettable. Tapioca Starch Tapioca starch is widely used in Thailand as an additive for enhancing the strength of paper. A few investigations have studied the properties of tapioca starch for the paper industry but many more have studied corn starch which is widely used in North America. Bemiller & Whistler (2009) explained that tapioca starch is obtained from the root of the cassava plant, which is found in equatorial regions between the Tropic of Cancer and the Tropic of Capricorn. Names for the cassava plant vary, depending on the region: yucca (Central America), mandioca or manioc (Brazil), tapioca (India and Malaysia) and cassada or cassava (Africa and South East Asia). In North America and Europe, the name cassava is generally applied to the root of the plant, whereas tapioca is the name given to starch and other processed products. Chavalparit & Ongwandee (2009) reported on the tapioca starch-processing industry that plays an important role in Thailand s agricultural economy. Known as one of the world s largest producers and exporters of tapioca starch; Thailand produced over seven million tons of starch in Tapioca was produced from treated and dried cassava root and used in the food, paper, and toothpaste industries. Only 20% of the cassava root harvested in Thailand was delivered to starchprocessing plants, while the rest was used in the production of pellets and chips. 23

38 Properties of Starch General specifications of cassava starch are summarized in Table 5. Bemiller & Whistler (2009) stated that tapioca starch is differentiated from other starches by its low level of residual materials (fat, protein, ash), lower amylose content than for other amylose-containing starches as shown in Table 6, and high molecular weights of amylose and amylopectin. Table 5. General specification of native cassava starch (Bemiller & Whistler, 2009) Table 6. Tapioca starch in comparison to other commercial starches (Bemiller & Whistler, 2009) 24

39 Data for the molecular weight and for amylose content in the major commercial starches that are used for papermaking are shown in Table 7 as reported by Maurer (2006). The preferred starch for use at the wet end of the paper machine will have a high molecular weight and low content of amylose. Table 7. Degree of polymerization and molecular weight of commercial starches (Maurer, 2006) Starch Modification Bemiller & Whistler (2009) stated that tapioca starch is easily modified to all current commercial derivatives. There are no special precautions or equipment required beyond what already might be practiced for a particular derivative or reagent applied to other starches. According to Maurer (2006), the hydroxyl groups can be reacted to form ethers, esters, acids, or cross-links. Bifunctional reagents will induce cross-linking between starch molecules. Charge is induced by reaction with monomers that contain a charged moiety. The degree of substitution (DS) for a starch is the average number of functional groups substituted onto the reactive sites of the anhydroglucose rings. In industrial practice, DS by monomer ranges from about 0.01 to 0.2. Considering that 25

40 starch has 3 hydroxyl groups, a DS of 0.01 to 0.2 means that 1 to 20 hydroxyls are substituted per 100 glucose units or 300 hydroxyls. The DS describes an average but gives no information of the position within starch granules or along the molecular chains. Excessive placement of substituents on the outside of granules or too much substitution (high DS) might interfere with thermal dispersion and can be detrimental to starch quality. Cationic Starch Hubbe (n.d.) illustrated the chemical structure of part of a cationic starch molecule as shown in Figure 8. Note that the typical degree of substitution was only about 0.02 to Maurer (2006) mentioned that charged moieties on starch induced a zeta potential, depending on ph. In an acid aqueous medium (low ph), some protonation may occur on starch, which would cause a slightly positive (cationic) charge. Charge neutrality is obtained at the isoelectric point of about ph 6.5. Most commercial cationic starches are quarternary amino derivatives. They are widely used at the wet end of the paper machine and for surface sizing as reported by Maurer (2001). Bemiller & Whistler (2009) commented that starches containing tertiary amino groups should only be used in an acid papermaking system (ph < 5.5), since they required protonation in order to become charged. Quartenary ammonium starches are inherently charged. They can be used at ph levels above 7, but their efficiency may be reduced at high ph due to screening by hydroxyl ions in the dispersion. 26

41 Figure 8. Chemical structure of part of a cationic starch molecule (Hubbe, n.d.) Anionic Starch Maurer (2006) explained that anionic starches are synthesized by reacting starch with phosphoric acid, alkali metal phosphate, by the introduction of carboxyalkyl groups as substituents, or by oxidation. Anionic charge can be introduced into starch through reaction with sodium monochloro acetate, which generates carboxymethyl substituted products. Amphoteric Starch By applying both cationic and anionic substitution, amphoteric products can be obtained. If both a cationic and anionic moiety are introduced into starch, an amphoteric product would result, said Maurer (2006). The cationic groups are the same quaternary ammonium substituents used in preparation of cationic starches. The anionic groups usually are phosphates. Strictly speaking all cationic potato starches are really amphoteric starches since potato starch contains about 0.08% phosphorous. The cationic content of amphoteric starches is typically in the range of 0.2 to 0.3% nitrogen. All of these products 27

42 are delivered to the mill as a dry powder having a moisture content of 10 to 20%. A typical ratio of sites on amphoteric starch is illustrated by Hubbe (n.d.) in Figure 9. Figure 9. Diagram illustrating a typical ratio of sites on amphoteric starch (Hubbe, n.d.) Octenyl Succinic Anhydride Modified Starch (OSA) Sweedmana et al. (2013) reviewed that OSA starches are obtained from the esterification reaction between starch hydroxyl groups and octenyl succinic anhydride as shown in Figure 10. When modified with OSA, the normally hydrophilic starch gains a hydrophobic element in the form of octenyl groups, resulting in whole molecules with an amphiphilic character. A commonly used parameter in this regard is the degree of substitution, DS, which is the average number of octenyl succinate, OS, derivatives per glucose unit. Profitable future directions of OSA starch include the correlation between the macromolecules structure and their emulsion stabilizing, encapsulating, pasting or digestive properties. Specific attention should be paid to the influence of the intrinsic highly branched structure of starch chains, which makes starch such a unique 28

43 polysaccharide when compared to other common bio-sourced polymers like cellulose. Bai (2008) concluded that OSA modification was affected by ph, starch slurry solids, OSA concentration and physical form of starch. Figure 10. Structure of OSA-modified starches (Sweedmana et al., 2013) 29

44 STICKINESS AND AGGLOMERATION BETWEEN STICKIES AND TAPIOCA STARCH POLYMERS ON UNBLEACHED PULP INTRODUCTION Over the past half century, the recovery and utilization of recovered paper has increased throughout the world, and this trend will continue. However, increased recovered paper collection is detrimental to paper quality as stated by Miranda et al. (2008). Furthermore, Doshi (2009) noted that several types of adhesives are used in papermaking and converting operations. Behavior of these adhesives, together with others introduced by paper and board users, is of interest to the paper recycling industry. Both synthetic and natural adhesives are used in the industry. Doshi et al. (2003) summarized that macro-stickies and micro-stickies primarily originate from adhesives such as SBR, EVA, and polyacrylates. On the other hand, dispersed, colloidal and dissolved stickies arise from adhesives as well as starches, wood pitch, and PVAc. Barreira (2010) noted that pitch can be defined as lipophilic extractives from wood, which composition consists basically of a complex mixture of different organic compounds, such as fatty acids, resinoic acids, sitosterol, waxes, steroiral esters and triglycerides. The major challenge is to avoid the natural tendency toward agglomeration and precipitation by stabilizing the other side of the equilibrium, the dispersed state. Many methods have been used to identify the characteristics of stickies. Sarja (2007) proposed that solvent extraction should be the basis of the stickies measurement method, as it took into account stickies of all sizes, and afterwards analytical instruments can be used for analysis of the extract. Castro et al. (2003) investigated synthetic 30

45 polymers and components of stickies deposits by using a thermogravimetric technique. The results of Thermogravimetric Analysis (TGA) can be used for analyzing the basic features of the organic components and calculating the amount of synthetic polymers, such as stickies in wastepaper. Adhesion Tests Several methods have been revealed for studying the properties of adhesion between adhesives and polymers. Yan Z. et al. (2003) studied the synthesis and application of water-based cationic PSAs using miniemulsion polymerization. They stated that the measurement of peel adhesion involved a bonding step and a debonding (or peeling) step. The debonding process involved a rapid deformation of the adhesive mass. Thus, the higher the peel strength, the higher the PSA s ability to resist bond deformation at high strain rates. Peel strength gave a measure of adhesive or cohesive strength, depending on the mode of failure. Shear resistance was measured as the force necessary to pull the PSA material parallel to the surface to which it was affixed with a definite pressure; it measured the cohesion strength of the PSA. In this research, the tack tester measuring the peel strength was used for studying the effects between diverse stickies from Carbotac and rosin size representing the stickies from synthetic and natural deposits. Another method used for analyzing the surfaces of the tapioca starch treatments on stickies was the atomic force microscope (AFM). Furuta & Gray (1998) have demonstrated that the atomic force microscope (AFM) can be a powerful tool for characterizing surfaces, as it can image surface topography, measure surface forces, and determine mechanical properties. 31

46 MATERIALS AND METHODS Unbleached Pulp 1. Double Lined Kraft (DLK) : This waste paper consisted of baled new corrugated cuttings having corrugating medium flutes and kraft liners as shown in Figure 11. It was cleaner than the usual old corrugated container types in the market which are used by end users. The trimmed waste from a box plant was conveyed directly to a recycling plant for removal of contaminants. It was processed by Sonoco Recycling in the United States. Figure 11. Double Lined Kraft (DLK) from Sonoco Recycling Double Lined Kraft preparation for the experiments is presented in Figure 12 below. First, the pulp was disintegrated with water in the hydropulper at medium speed for 90 minutes. Second, the disintegrated pulp fiber was drained and dewatered in a screen container. Third, the wet pulp was centrifuged to remove more water. Finally, the moist pulp chunk was fluffed by using the shredder before storing in the cool room at 4 C. 32

47 (a) (b) (c) (d) (e) (f) Figure 12. The preparation process of DLK, (a) the mixing tank, (b) the disintegration of pulp in the hydropulper, (c) draining the water out, (d) the centrifuge, (e) fluffing the pulp chunk with a shredder, (f) the fluff pulp 2. Semi-Chemical Pulp (SCP) : This pulp as shown in Figure 13 produced with mechanical and chemical methods was made by a caustic/carbonate process. It was produced by Sonoco at Hartsville, South Carolina in the United States. 33

48 Figure 13. Semi-Chemical Pulp from Sonoco at Hartsville, South Carolina (a) (b) (c) (d) Figure 14. The preparation process for SCP, (a) the refiner, (b) the refiner plates, (c) draining the water out, (d) the refined SCP Unrefined SCP was refined by the refiner to lower freeness and develop more fibrils as shown in Figure 14. The water in the refined pulp was drained out before storing in the cold room at 4 C. The moisture content of DLK was tested using TAPPI method of 34

49 Moisture in Pulp, Paper and Paperboard (T412). The percentage of moisture content was calculated from (W1 - W2) x 100 / (W1) where W1 is initial specimen weight and W2 is dry specimen weight. The result is shown in Table 16 in Appendix A. Adhesives 1. Carbotac : Carbotac is an acrylic-based polymer emulsion designed as a pressure sensitive adhesive for use in many applications. According to the certificate of analysis, it was a 49.30% solids anionically stabilized acrylic emulsion. The viscosity was 66 cps at 25 C and it is moderately shear thinning. It had a ph of 2.2 that would be increased when the viscosity was higher. It was produced by Lubrizol Advanced Materials, Inc., Ohio. Figure 15. Carbotac by Lubrizol Advanced Materials, Inc., Ohio 2. Paraffin Wax : Paraffin-based wax has traditionally been used as a coating for protecting against external moisture. It is a byproduct from the refining of lubricating oil. This Paraffin Wax was obtained from Fisher Inc. 35

50 Figure 16. Paraffin wax by Fisher Inc. 3. Rosin Gum : It is yellow crystalline chucks and powder. The melting point is from 75 C to 81 C. It was supplied by Acros Organics. Figure 17. Rosin gum by Acros Organics 4. Rosin Powder, with Diluent : Rosin is an ingredient in adhesives, printing inks, and sealing wax. It is insoluble in water. The melting point is from 100 C to 150 C. It was supplied by Fisher Chemical. 36

51 Figure 18. Rosin powder, with diluent by Fisher Chemical 5. Rosin Size, Champion 77 (Plasmine Technology) : Its solids was 76-78% as detailed in the material safety data sheet. It was provided by Chemtrec. Figure 19. Rosin size, Champion 77 (Plasmine Technology) by Chemtrec Starch 1. Tapioca Starch : It was a natural tapioca starch supplied by Aquasol Corporation. Figure 20. Tapioca starch by Aquasol Corporation 37

52 2. AquaBloc 252T : It was a modified sodium carboxymethyl tapioca starch anionically (CMC). The degree of substitution (DS) of 0.5 was obtained with full molecular weight. It was produced by Aquasol Corporation. Figure 21. AquaBloc 252T by Aquasol Corporation 3. AquaFlocc 330T : This modified cationic quaternary tapioca starch was produced by Aquasol Corporation. It was full molecular weight and had a degree of substitution (DS) of 0.3. Figure 22. AquaFlocc330T by Aquasol Corporation ` 4. Aquajel 65205TO : It was a modified carboxymethyl tapioca starch anionically (CMC) with full molecular weight and a degree of substitution (DS) 38

53 of 0.5. It also was substituted with 5% hydrophobic octenyl succinic anhydride (OSA). It was produced by Aquasol Corporation. Figure 23. Aquajel 65205TO by Aquasol Corporation 5. Aquajel 73005TO : This modified cationic quaternary tapioca starch was produced by Aquasol Corporation. It was full molecular weight and had the degree of substitution (DS) of 0.3 with 5% hydrophobic octenyl succinic anhydride (OSA). Figure 24. Aquajel 73005TO by Aquasol Corporation Testing Materials 1. Cloth : Tork Premium Specialist Cloth cleaning wiper was used for the Instron 39

54 tack testing. It was made from an extra strong and fast absorbing non-woven microstructure. The die cut sheets had virtually no lint. It contained 100% synthetic and virgin fibers. Figure 25. Premium specialist cloth by Tork Figure 26. Strip cutter for Tork cloth The cloth was prepared carefully by cutting on the standard machine used for paper testing. The long edges were parallel. The widths at the opposite ends were within 15mm. of each other. 40

55 2. Plain Microscope Slides : Glass slides were the coupons used to adhere the cloth for testing the peel strength. The size of the slide was 75 x 38 x 1.0 mm. It was purchased from Fisherbrand, Fisher Scientific. Figure 27. Microscope slides, 75 x 38 x 1.0 mm. by Fisher Scientific. 3. Frosted Microscopes Slides : Fross glass slides were used to form the film for testing on the Atomic Force Microscope (AFM). The size of slide was 1 inch x 3 inches with the thickness of mm. It was produced by Eisco. Figure 28. Microscope slides, 1 x 3 by Eisco. 4. Differential Scanning Calorimetry (DSC) Standard Aluminum Pans and Lids : This pan was used for containing a liquid sample before placing it on a thermogravimetric analysis (TGA) pan. It was produced by TA Instruments. 41

56 Figure 29. DSC standard aluminum pans and lids by TA Instruments Reagents for the solvent extraction 1. Benzene : HPLC grade 99.5% liquid by Alfa Aesar. 2. Ethanol : Ethyl Alcohol, absolute 200 proof, 99.5+, A.C.S. reagent by Acros. 3. Hexanes : Technical grade, Naphtha Solvent by Fisher Scientific. SOLVENT EXTRACTION EXPERIMENTS Extraction with an organic solvent is a commonly used technique to separate hydrophobic substances from the pulp, water or deposit sample. The extraction may be carried out with different extraction techniques, such as Reflux, Soxhlet (or similar automated versions, e.g. Soxhtech and Soxhtherm), Accelerated Solvent Extraction (ASE), Supercritical Fluid Extraction (SFE), Solid Phase Extraction (SPE) or simply extracting the sample in a test tube, perhaps with the aid of ultrasound. (Sarja, 2007) There are many extracting solvents used as a solvent in the extraction of stickies from pulp such as Dimethyl formamide (DMF), Chloroform, Trichloroethane (TCE), Tetrahydrofuran (THF), Methyl-tert-butyl-ether (MTBE), Acetone, and Hexane. Dichlomethane (DCM) is often used in extracting deposits (Johansson et al., 2003). Lee & Kim (2006) used Ethanol, Hexane and Chloroform to get a better yield in analyzing the gravimetric amount of extract. 42

57 Experimental Procedures The experiment for the solvent extraction was described by the standard instructions from Solvent Extractives of Wood and Pulp (T204), TAPPI. The Ethanol- Benzene mixture of 3:1 was used as described in the manual. The apparatuses such as the extraction thimbles, a compact form of Soxhlet apparatus, the heating device, and the flasks were prepared. A chemical fume hood and personal protection equipment were required by the safety regulations. Extraction Procedure: 1. Fill the extraction thimble with the shredded pulp. Then, place a filter paper on the top of the thimble to prevent any loss of the specimen. 2. Place the extraction thimble with specimen in a clean and dry Soxhlet extraction apparatus. Connect the Soxhlet extraction apparatus in an upright position to a clean and dry round bottom extraction flask. 3. Fill the extraction flask with 150 ml of the solvent. 4. Connect the flask to the extraction apparatus and started water flow to the condenser section. Adjust the heater to provide a boiling rate which cycles the solvent through the specimens for over 8 hours. 5. Remove the flask from the apparatus and evaporate the solvent in the extraction flask to dryness. 6. Put the extraction flask with the dried extract in the vacuum oven overnight. 7. Weigh the dried extract and the residue in the thimble. 8. Scratch the dried extract from the flask. Place it in a vial for other tests. 43

58 The Comparison of Effective Solvent Reagents Ethanol-Benzene mixtures and Hexanes were evaluated for the appropriate reagent to be used on this experiment. (a) (b) Figure 30. Comparison of the reagents with (a) Ethanol-Benzene mixture and (b) Hexanes in the Soxhlet Extraction apparatus over 8 Hours Table 8. The % extractives of DLK 100%, DLK and stickies with the Hexanes reagent 44

59 (a) (b) (c) (d) Figure 31. The extractives from the Ethanol-Benzene mixture reagent on (a) DLK, (b) DLK and stickies, (c) The different ratios of DLK and SCP, (d) SCP and stickies Table 9. The % extractives of DLK 100%, DLK and stickies, The different ratios of DLK and SCP, SCP and stickies with the Ethanol-Benzene mixture reagent 45

60 After solvent extraction for over 8 hours, the solvent in the flasks with the ethanol-benzene mixture had darker solvent than the flasks from hexanes indicating more extract yield as shown in Figure 30. From Table 8, the percent of extractives with hexane as the solvent was around 0.2%, which gave a small amount of yellow extract at the bottom of the flask after evaporating to dryness. Figure 31 and Table 9 show the different results from using the ethanol-benzene mixture on DLK, SCP, and the diverse stickies. THERMOGRAVIMETRIC ANALYSIS (TGA) EXPERIMENTS AND RESULTS Thermogravimetric Analysis (TG) or Thermal Gravitric Analyisis (TGA) provides information about changes in physical and chemical properties of materials that are measured as a function of increasing temperature, or as a function of time. It is commonly used to determine selected characteristics of materials that exhibit either mass loss or gain due to decomposition. Castro et al. (2003) reported that a simple technique for the determination of synthetic polymeric additives using pyrolysis TG has been developed. TG may be used also without a fractionation step for the analysis of polymers in colloidal solids of process water and in paper machine stickies deposits. Barnetoa A.G., Vilab C., & Arizaa J. (2011) mentioned that Thermogravimetric analyses can be used to monitor the pulping process in a pulp mill. The chemical changes that wood and pulps undergo influence their thermal degradation behavior. 46

61 Experimental Procedures TGA runs were carried out with a TGA Q500 by TA Instruments on samples of around 10-15mg under a constant nitrogen flow, using temperatures from 40 C to 600 C. A platinum pan was used for carrying the samples in the furnace. A DSC pan was placed on the platinum pan for the liquid samples before testing to decrease the chance of having a problem with stickiness as shown in Figure 32. The calibrating tare for the experimental pan was determined before the sample was placed on the pan. Figure 33 shows the TGA instrument at the Department of Forest Biomaterials Laboratory of North Carolina State University that was used in this experiment. Figure 32. Thermogravimetric Analysis Instrument (TGA) Figure 33. The liquid sample was placed on the DSC pan before loading on the platinum TGA pan 47

62 Decomposition Analysis of Extractives and Adhesives The Pyrolysis Analysis of Adhesives and Tapioca Starch The pyrolysis analysis of the various kinds of adhesives was tested on the TGA for the comparative analysis of natural tapioca starch and stickies as shown in Figures 34 and 35. Sample: Parafin Size: mg Method: Park proximate analysis 1 TGA File: F:...\Parafin Operator: Xueyong Ren Run Date: 13-Sep :02 Instrument: TGA Q500 V6.7 Build Weight (%) Deriv. Weight (%/ C) Weight (%) Deriv. Weight (%/ C) Temperature ( C) Universal V4.5A TA Instruments Sample: Rosin Powder Size: mg Method: Proximate TGA (a) File: F:...\Rosin Powder.001 Operator: Xueyong Run Date: 04-Nov :14 Instrument: TGA Q500 V6.7 Build Temperature ( C) Universal V4.5A TA Instruments (b) TGA Sample: Tapioca Starch File: F:...\Tapioca Starch.001 Size: mg Operator: Lalita Method: Proximate Run Date: 04-Nov :02 Instrument: TGA Q500 V6.7 Build Weight (%) Deriv. Weight (%/ C) Weight (%) Deriv. Weight (%/ C) Temperature ( C) Universal V4.5A TA Instruments Sample: Carbotac Size: mg Method: Lalita Procedure TGA (c) File: F:...\TGA \Carbotac.001 Operator: Lalita Run Date: 07-Feb :14 Instrument: TGA Q500 V6.7 Build Temperature ( C) Universal V4.5A TA Instruments Sample: RosinSize77 Size: mg Method: Lalita Procedure TGA (d) File: F:...\TGA \RosinSize Operator: Lalita Run Date: 07-Feb :10 Instrument: TGA Q500 V6.7 Build Weight (%) Deriv. Weight (%/ C) Weight (%) Deriv. Weight (%/ C) Temperature ( C) Universal V4.5A TA Instruments (e) (f) Figure 34. The thermal decomposition analysis of adhesives on TGA, (a) rosin gum, (b) paraffin wax, (c) rosin powder, (d) natural tapioca starch, (e) Carbotac, (f) rosin size (Champion77) 0 Temperature ( C) Universal V4.5A TA Instruments 48

63 Figure 35. The compositional analysis of pressure sensitive adhesives The weight loss as a function of temperature varies for each synthetic polymer sample. The concept of this experiment is that the pyrolysis stages for nitrogen for most of the synthetic polymers occur at higher temperatures than the pyrolysis temperatures of natural polymers such as cellulosic materials. Paraffin wax has a steep slope of weight loss. Its weight loss takes place at a low temperature from 200 C to 300 C. Rosin gum has a slightly higher decomposition temperature. It is pyrolysed between 200 C and 350 C. The next higher temperature curve is rosin size with a pyrolytic temperature from 300 C to 400 C. Carbotac shows the highest decomposition temperature range from 425 C to 475 C. The differences in these curves could be useful in deposit as extract analysis. 49

64 The Pyrolysis Analysis of Pulp Extractives DLK and SCP have the similar fiber and fine compositions. The blends of DLK and SCP were analyzed to give reference thermograms. Figure 36 displays the pyrolysis thermograms used for the analysis of DLK and SCP mixtures as the reference. 100 Instrument: TGA Q500 V6.7 Build Sample: SCP25%-DLK 75% EtOH&Benz Size: mg Method: Lalita Procedure 100 TGA File: F:...\SCP25%-DLK 75% EtOH&Benz.001 Operator: Lalita Run Date: 02-Dec :31 Instrument: TGA Q500 V6.7 Build Weight (%) Deriv. Weight (%/ C) Weight (%) Deriv. Weight (%/ C) Temperature ( C) Universal V4.5A TA Instruments Sample: SCP50% DLK50% EtOH&Benzene Size: mg Method: Proximate TGA (a) File: F:...\SCP50% DLK50% EtOH&Benzene.001 Operator: Lalita Run Date: 04-Nov :15 Instrument: TGA Q500 V6.7 Build Temperature ( C) Universal V4.5A TA Instruments (b) Sample: SCP75%-DLK 25% EtOH&Benz File: F:...\SCP75%-DLK 25% EtOH&Benz.001 Size: mg TGA Operator: Lalita Method: Lalita Procedure Run Date: 02-Dec :48 Instrument: TGA Q500 V6.7 Build Weight (%) Deriv. Weight (%/ C) Weight (%) Deriv. Weight (%/ C) Temperature ( C) Universal V4.5A TA Instruments (c) Sample: SCP 100% EtOH&Benzene Size: mg Method: Proximate 100 TGA Temperature ( C) Universal V4.5A TA Instruments File: F:...\SCP 100% EtOH&Benzene.001 Operator: Lalita Run Date: 04-Nov :37 Instrument: TGA Q500 V6.7 Build 203 (d) Weight (%) Deriv. Weight (%/ C) Temperature ( C) Universal V4.5A TA Instruments (e) Figure 36. The TGA thermal decomposition analysis of pulp extractives with an ethanolbenzene mixture, (a) DLK100%, (b) DLK75% : SCP25%, (c) DLK50% : SCP50%, (d) DLK25% : SCP75%, (e) SCP100% 50

65 Figure 37. The compositional analysis of SCP and DLK ethanol-benzene extractives by TGA for different pulp blends The pyrolysis graph of various pulp ratios in Figure 37 shows the effect of the different ratios. The percentage of weight loss in DLK is slightly higher than in SCP. The major weight loss of DLK and SCP is between 200 o C and 400 o C. Figure 38. The compositional analysis of natural tapioca starch and modified tapioca starch by TGA 51

66 The pyrolysis of different types of tapioca starch gives us the same range of decomposition temperature from 225 o C to 325 o C. The compositional analysis graph of natural tapioca starch, anionic tapioca starch, and cationic tapioca starch is shown in Figure 38. Figure 39. The compositional analysis of DLK ethanol-benzene extractives with different stickies compared to DLK100% by TGA The result from the extractives of DLK100% and stickies shows the same outline as SCP100% and stickies. There was a distinct difference between DLK100% only and DLK assorted with various stickies as shown in Figure 39. The weight loss of DLK and paraffin was the same as the analysis of paraffin only. Its temperature range was from 200 o C to 300 o C. The decomposition temperature of DLK and rosin gum was between 200oC and 350 o C, which is proportional to only rosin gum. The 52

67 extractive of DLK and Carbotac is pyrolysed from 300 o C to 400 o C, which is lower than the temperature of Carbotac alone at the range of 425 o C and 475 o C. Figure 40. The compositional analysis of SCP ethanol-benzene extractives with different stickies compared to SCP100% by TGA The graph of thermal analysis from the extractives of SCP100% and stickies is shown in Figure 40. The graph is for a system comprized of stickies mixed with SCP extractives. The SCP100% has a different line from the weight loss lines mixed with stickies. The decomposition temperature of SCP and paraffin is between 200 o C and 300 o C which is the same range as the decomposition of pure paraffin. The slope of weight loss in SCP and Carbotac occurs at a lower temperature than the decomposition analysis of Carbotac alone. Its temperature range is from 300 o C to 400 o C. Therefore, TGA is useful for identifying the compositional materials in extractives and deposits. 53

68 MUFFLE FURNACE EXPERIMENT The ash content of paper contains various inorganic residues from fillers, from the pulp, and from added chemicals in the paper making process. The weight loss of ashes at various temperatures can be used to identify the materials in the ash. The temperature at 525 o C can remove cellulose and moisture from the specimen according to the TAPPI standard of T211 and T413. The combustion at 900 o C can convert the calcium carbonate to calcium oxide. However, the variable compositions need more data to be considered a significant result. The calculation of the ash content was calculated using the equation, [ Ash, % = (A x 100) / B ], where A = weight of ash (g) and B = weight of test specimen (g moisture free). Figure 41. The Muffle Furnace Table 10. The ash from the pulps, the starches, and the adhesives at 400 o C and 900 o C 54

69 (a) (b) (c) Figure 42. The crucibles for testing ashes were composed of DLK, SCP, Carbotac, paraffin wax, rosin gum, rosin powder, rosin size, natural tapioca starch respectively, (a) the adhesive and pulp samples before ignition, (b) the ash at 400 o C, (c) the ash at 900 o C Table 11. The ashes from the starches and the adhesives at 750 o C and 900 o C (a) (b) (c) Figure 43. The crucibles for testing ashes were composed of Carbotac, paraffin wax, rosin gum, rosin powder, rosin size, natural tapioca starch respectively, (a) the adhesive samples before ignition, (b) the ashes at 750 o C, (c) the ashes at 900 o C 55

70 According to Table 10 and Figure 42, DLK and SCP were ignited between 400 o C and 900 o C, leaving only a little remaining ash after burning at 900 o C. The combustion of cellulose occurred at 300 o C. It showed that the pulps contained small amounts of fillers which underwent negligible change in weight on ignition. Carbotac, paraffin wax, and tapioca starch were burnt between 400 o C and 900 o C. Rosin gum left some ashes after raising the temperature to 400 o C. The ignition of rosin gum was from 400 o C to 750 o C. Rosin powder and rosin size left some residues in the crucibles even at 900 o C. It showed that there were inorganic material components in these samples. The results of ignition between 750 o C and 900 o C were shown in Table 11 and Figure 43. The complete tables from the ignition were shown in Appendix. PARTICLE SIZE EXPERIMENT Particle sizes have many effects on the properties of materials and can affect the quality and performance of objects. In this work, the particle size was measured by a Laser scattering particle size distribution analyzer, LA300, Horiba. The principle of measurement is based on Mie scattering theory. The size range of particles can be displayed from 0.1 to 600 micrometers in diameter. The measurements were performed using a 650-nm laser diode. Six wide-angle detectors and a 36-channel ring-shaped silicon photo-diode array detector acted as receptors for light refracting off of particles suspended in the flow cell. Electrical signals corresponding to the intensity of the scattered light were used to calculate the size distribution of the particles as shown in Figure

71 Figure 44. The measurement principles of a laser scattering particle size distribution analyzer Figure 45. Laser scattering particle size distribution analyzer, LA300, Horiba The particle size analyzer was calibrated with COUNT-CAL Count Precision Standards, NIST Traceable Mean Diameter certified by National Institute of Standards and Technology (SRM 2800 SN411). The microsphere size standards consist of polystyrene suspended in ultraclean diluent at a concentration of 3000 particles per millimeter. The nominal diameter was 25 microns. 57

72 Figure 46. Particle Size Standards Experimental Procedure: 1. Pour DI water into the sampling chamber until it reaches the line. 2. Calibrate the initial alignment by using the particle size standard at 25 ml. 3. Drain and wash the chamber using water. 4. Pour DI water into the chamber, then, click on Alignment and Blank on the screen for setting. 5. Put a small amount of sample into the chamber around 10mg to 5g depending on each sample and disperse it evenly. 6. Click on Auto1 to run the test. The particle sizes of stickies, uncooked tapioca starch, and cooked tapioca starch tested on the particle size distribution analyzer are shown in Table 12 and 13. The low particle sizes of stickies are obtained from the liquid compounds such as Carbotac and rosin size. The granular particles from rosin powder and rosin gum are the higher particle sizes. The averages of particle sizes from Carbotac, rosin size, rosin powder, and rosin gum are microns, microns, microns, microns respectively. 58

73 Table 12. Average particle sizes of stickies in microns by Horiba Rosin Rosin Rosin Carbotac Size77 Powder Gum Table 13. Average particle sizes of uncooked and cooked tapioca starches at 0.05% in microns by Horiba Uncooked Tapioca Starch Cooked Tapioca Starch Anionic Cationic Anionic Cationic Natural Natural Aquabloc Aquaflocc Aquabloc Aquaflocc Starch Starch 252T 330T 252T 330T (0.05%) (0.05%) (0.05%) (0.05%) (0.05%) (0.05%) Table 14. Average particle sizes of cooked tapioca starch at 0.05% and Carbotac at 0.25% in microns by Horiba Cooked Tapioca Starch Anionic Cationic Natural Starch (0.05%) Aquabloc 252T (0.05%) Aquaflocc 330T (0.05%) + Carbotac (0.25%) + Carbotac (0.25%) + Carbotac (0.25%) The uncooked tapioca starches modified as the anionic starch and the cationic starch have the sizes of particles at microns and microns which are higher than the mean particle size of uncooked natural starch at microns. The result is related to the particle sizes of cooked tapioca starches. The mean particle sizes of cooked anionic tapioca starch at micron and cooked cationic tapioca starch at microns are obviously higher than cooked natural starch at microns. The average particle sizes of mixtures of different tapioca starches at 0.05% and Carbotac at 0.25% are shown in Table 14. The result shows that when cooked natural 59

74 tapioca starch is mixed with Carbotac, the particle size is decreased to microns which is close to the average size of Carbotac. The cooked anionic tapioca starch blended with Carbotac has a particle size of microns which is similar to the particle size of Carbotac. In case of the cooked cationic tapioca starch, although its particle size at microns rapidly drops after mixing with Carbotac, it is still higher than other cooked starches in this experiment. INSTRON TESTER EXPERIMENT AND RESULTS The Instron was designed to test loads of materials in a wide range. It is composed of a load frame, a drive motor, and software for analyzing the data. The crosshead can travel vertically. The load cell measured the resulting load on the specimen. The Instron Model 4443 was used for measuring the peel strength. The cloth was soaked in a solution of either adhesives, starch polymers, or both of them for 5 minutes. The soaked cloth was placed on the microscope glass slide and pressed by a rubber roll once before moving it to the oven for removing the moisture. The sample was left in the 80 o C oven at least 20 minutes for drying. The sample was attached to the glass slide afterwards. The pictures related to testing are shown in Figure

75 (a) (b) (c) (d) Figure 47. The peel strength testing by the Instron, (a) the soaked cloth in the solvent, (b) the soaked cloth pressed with the rubber roller, (c) the moist sample was dried in the oven, (d) the sample was measured on the Instron A load cell with a maximum load of 0.5 kilogram force (kgf) was provided for the test. The glass slide was held by the lower clamp on the load frame. The edge of the cloth was attached to the upper holder. The crosshead attached to the load cell moved up to peel the sample off of the glass slide. The peel strength was measured and shown on the screen by the Instron software. The configuration of the Instron is shown in Figure 48. The Instron used in the experiment was shown in Figure

76 Figure 48. The ghost view of the Instron instrument Figure 49. Instron tack tester model 4443 The concentration of DLK pulp at 3.81% and the concentration of SCP pulp at 10.32% as received were mixed with the DI water and were heated by leaving them overnight in the oven before filtering the pulp out. The DLK and SCP extracts were tested using the same procedure as testing the peel strength above. 62

77 (a) (b) (c) (d) Figure 50. The extracts from DLK and SCP, (a) the extracts after heating overnight in the oven, (b) filtering the pulp out, (c) DLK extract with Carbotac, (d) SCP extract with Carbotac The peel strength was measured on the model stickies such as Carbotac, rosin powder, and rosin size (Champion77) and also on the cooked tapioca starches with different charges. The results from the tack tester showed that the peel strength increases when we added more chemicals from 0.25%, 0.50%, 0.75%, and 1.00% respectively. Cooked tapioca starches tended to provide more peel strength than the stickies. Both DLK extract and SCP extract had low adhesive strength as shown in Figure

78 Figure 51. Peel strength of cooked tapioca starch and stickies with DI water 64

79 DLK extracts and SCP extracts were studied with addition of stickies to observe changes in peel strength. From Figure 52, the peel strength rose continuously in proportion to addition of adhesive materials. The adhesive force was similar to the trials mixing stickies in DI water alone. (a) (b) Figure 52. Peel strength of stickies in (a) DLK extract and (b) SCP extract The results on Instron from Carbotac : After mixing Carbotac with the cooked natural tapioca starch, the cooked anionic tapioca starch (Aquabloc252T) and the cooked anionic OSA tapioca starch (Aquajel 65205TO), the suspensions were homogeneous solutions as in Figure 53 and 55. In contrast, when Carbotac was mixed in the cooked cationic tapioca starch (Aquaflocc330T) and the cooked cationic OSA tapioca starch (Aquajel 73005TO), white agglomerated particles floated on the surface as shown in Figure 54 and Figure 56(d). 65

80 Figure 53. Cooked natural tapioca starch at 0.05% with Carbotac Figure 54. Cooked cationic tapioca starch (Aquaflocc330T) mixed with Carbotac (a) (b) (c) Figure 55. Pictures of the cooked anionic carboxymethyl OSA tapioca starch (Aquajel 65205TO) mixed with four different percentages of Carbotac from 0.25%, 0.50%, 0.75%, and 1.00% respectively. The various concentrations of starch were (a) 0.05%, (b) 0.15%, (c) 0.25% 66

81 (a) (b) (c) (d) Figure 56. Pictures of shows the cooked cationic quaternary OSA tapioca starch (Aquajel 73005TO) mixed with four different percentages of Carbotac from 0.25%, 0.50%, 0.75%, and 1.00% respectively. The various percentages of starch were added at (a) 0.05%, (b) 0.15%, (c) 0.25%. The clear picture of agglomeration is shown in (d) As shown in Figure 57(a), cooked tapioca starch was tested with Carbotac. The increase of peel strength took place in all different ratios of Carbotac when cooked tapioca starch was used at 0.05%, 0.15%, 0.25%, and 0.50% consecutively. The cooked tapioca starch at 0.25% itself with no Carbotac had higher peel strength than when mixing it with Carbotac. The anionic tapioca starch has an increasing peel strength trend from a low level to a high level as shown in Figure 57(b). When the anionic tapioca starch was added to the various amounts of Carbotac, the peel strength generally went up with starch concentration although the value was lower at 0.25% of starch solution. When Carbotac was mixed with cationic Aquaflocc330T as shown in Figure 57(c), 67

82 there were steep peaks at 0.05% of starch concentration at all amounts of Carbotac. The two highest peaks reached about kgf which were very high values compared to other added starch types. Then, the peel strength decreased before increasing slightly to around 0.1 kgf at 0.50% of starch solution. The cooked anionic OSA tapioca starch (Aquajel 65205TO) mixed with the various amounts of Carbotac had a continuously increasing trend with starch concentration. The highest peak was kgf from the anionic starch at 0.50% alone without Carbotac as shown in Figure 57(d). In the case of the cooked cationic OSA tapioca starch (Aquajel 73005TO), the shape of this plot was similar to the graph of the cooked cationic tapioca starch (Aquaflocc330T). The peaks of each stickies concentration jumped to the highest points at a starch concentration of 0.05% and Carbotac at 0.25% as shown in Figure 57(e). 68

83 (a) (b) (c) (d) (e) Figure 57. Peel strength of cooked tapioca starch and Carbotac at various percentages, (a) cooked natural tapioca starch, (b) cooked anionic tapioca starch (Aquabloc252T), (c) cooked cationic tapioca starch (Aquaflocc330T), (d) cooked anionic OSA tapioca starch (Aquajel 65205TO), (e) cooked cationic OSA tapioca starch (Aquajel 73005TO) 69

84 The results on Instron from rosin size (Champion77): The mixture of rosin size (Champion77) and the cooked cationic tapioca starch solution (Aquaflocc330T and Aquajel73005TO) flocculated and formed small clumps in the solution at some suitable concentrations. The white jelly clusters appeared less when the cooked cationic tapioca starch concentration increased more as shown in Figure 58 and 59. (a) (b) (c) (d) Figure 58. Pictures of shows the cooked cationic tapioca starch (Aquaflocc330T) mixed with four different percentages of rosin size (Champion77) from 0.25%, 0.50%, 0.75%, and 1.00% respectively. The various percentages of starch were added at (a) 0.05%, (b) 0.15%, (c) 0.25%, and (d) 0.50%. 70

85 (a) (b) (c) (d) (e) Figure 59. Pictures of shows the cooked cationic quaternary OSA tapioca starch (Aquajel 73005TO) mixed with four different percentages of rosin size (Champion77) from 0.25%, 0.50%, 0.75%, and 1.00% respectively. The various percentages of starch were added at (a) 0.05%, (b) 0.15%, (c) 0.25%, and (d) 0.50%. The clear picture of agglomeration is shown in (e) Unlike the addition of the cooked cationic tapioca starch in rosin size (Champion77), when the anionic tapioca starches (Aquabloc252T and Aquajel 65205TO) were used, there was no agglomeration at any conditions. The mixtures were mixed into the same solutions as displayed in Figure 60 and

86 Figure 60. Cooked anionic tapioca starch (Aquabloc252T) mixed with rosin size (Champion77) (a) (b) (c) (d) Figure 61. Pictures of shows the cooked anionic carboxymethyl OSA tapioca starch (Aquajel65205TO) mixed with four different percentages of rosin size (Champion77) from 0.25%, 0.50%, 0.75%, and 1.00% respectively. The various percentages of starch were added at (a) 0.05%, (b) 0.15%, (c) 0.25%, and (d) 0.50% When the cooked tapioca starch was combined with the rosin size (Champion77), the peel strength rose to a peak at 0.05% of starch solution; afterwards the results declined to below kgf at 0.15% and 0.25% of starch solution. Then, the peel strength increased again at the high starch concentrations as shown in Figure 62(a). 72

87 Cooked Natural Tapioca Starch and Rosin Size Peel Strength (kgf) % 0.50% 0.75% 1.00% No Rosin Size No Starch 0.05% 0.15% 0.25% 0.50% The Percentage of Starch (a) (b) (c) (d) (e) Figure 62. Peel strength of cooked tapioca starch and rosin size (Champion77) at the different percentages, (a) cooked natural tapioca starch, (b) cooked anionic tapioca starch (Aquabloc252T), (c) cooked cationic tapioca starch (Aquaflocc330T), (d) cooked anionic OSA tapioca starch (Aquajel65205TO), (e) cooked cationic OSA tapioca starch (Aquajel73005TO) From examination of Figure 62(b), we can see the tendency of gradually rising peel strength when we increased concentrations of cooked anionic tapioca starch 73

88 (Aquabloc252T) in rosin size mixtures. The lines reached the highest peaks at 0.50% of starch solution at every concentration of rosin size. These progressions appeared in the same way with the mixtures of cooked anionic OSA tapioca starch (Aquajel65205TO). The graphs in Figure 62(b) and 62(d) show that the cooked anionic starch alone with no size gave a greater peel strength than the combination of the stickies and tapioca starch. The graph in Figure 62(c) shows a more unstable peel strength in each line of the blends between the cooked cationic tapioca starch (Aquaflocc330T) and rosin size. However, there is an upward slope of peel strength with starch concentration at all concentrations of rosin size, as the concentration of cooked cationic starch increased, although there was an isolated peak at the combination of 0.25% starch solution and 1.00% rosin size. A similar trend was shown in Figure 62(e) when the cationic OSA tapioca starch (Aquajel73005TO) was combined with rosin size. However, the entire peel strength from the cationic starch with OSA gave a lower range of strength compared to the cationic starch without OSA. ATOMIC FORCE MICROSCOPY (AFM) EXPERIMENT AND RESULTS Atomic force microscopy (AFM) or scanning force microscopy (SFM) is the common scanning probe technique with high-resolution for material characterization. Rugar (1990) stated that the concept of using a force to image a surface is a general one and can be applied to magnetic and electrostatic forces as well as to the interatomic interaction between the tip and the sample. Li (1997) mentioned that there are three commonly used techniques for AFM as shown in Figure 63. First, The Contact Mode where the tip scans the sample in close contact with the surface is the common mode 74

89 used in the atomic force microscope. The force on the tip is repulsive with a mean value of 10-9 N. This force is set by pushing the cantilever against the sample surface with a positioning element. Second, the Non-Contact Mode is used in situations where tip contact might alter the sample in subtle ways. Attractive Van der Waals forces acting between the tip and the sample are detected, and topographic images are constructed by scanning the tip above the surface. Lastly, Tapping Mode is a key advance in AFM. This powerful technique allows high resolution topographic imaging of sample surfaces that are easily damaged, loosely hold to their substrate, or are difficult to image by other AFM techniques. Tapping mode alternately places the tip in contact with the surface to provide high resolution and then lifts the tip off of the surface to avoid dragging the tip across the surface. (a) (b) (c) Figure 63. Three commonly used techniques for AFM, (a) the contact mode, (b) the non-contact mode, and (c) the tapping mode The force-distance curve is a fundamental way to describe the contact mode. A schematic of a force curve is depicted in Figure 64. The force curves expose a variety of sample properties, such as adhesion and compliance. The total contact force is dependent on the adhesion including the applied load. 75

90 Figure 64. The force distance curve. The approach (red) and withdraw (blue) curves are shown on the right The Atomic Force Microscope (AFM) that was used in this work was a Bruker Dimension 3000 at the Analytical Instrumentation Facility, Monteith Research Center at North Carolina State University. The contact mode was utilized for comparing the treated and untreated surface on force curve plots. (a) (b) Figure 65. (a) The Atomic Force Microscope (AFM) analytical instrument, (b) The tip for the contact mode 76

91 The contact mode tip used in this experiment was CONTPt-10 from Nanoworld. The complete information for this tip is shown in Figure 66. The tapping mode tip used for testing on the AFM was the model AC240TS from Asylum Research as shown in Figure 67. Figure 66. The contact mode tip for testing on AFM Figure 67. The tapping mode tip for testing on AFM The films were made on glass slides as shown in Figure 68 by mixing the adhesives at 0.1% as received with the different ratios of 0.05%, 0.15%, 0.25%, and 0.50% of natural tapioca starch, cationic tapioca starch, and anionic tapioca starch. The 77

92 drop of liquid mixture was placed on the glass slide before drying it in the oven at 80 o C for 15 minutes. Then, the process was repeated dropping the liquid and heating it in the oven for 3 times until a film was formed on the transparent slide. Figure 68. The liquid samples were dried in the oven to produce the films 78

93 (a) (b) (c) (d) (e) (f) Figure 69. The films were created on glass slides for testing on the AFM, (a) Aquabloc252T and Carbotac, (b) Aquabloc252T and rosin size (Champion77), (c) Aquaflocc330T and Carbotac, (d) Aquaflocc330T and rosin size77, (e) tapioca starch and Carbotac, (f) tapioca starch and rosin size (Champion77) AFM Results for Carbotac : The images and force plot of Carbotac at 0.25% tested by the tapping mode and the contact mode are shown in Figure 70 and 71. The surface of Carbotac filmed on the glass slide had the spike-like appearance while the surface of Carbotac with uncooked or cooked 79

94 tapioca starch looked smoother as shown in Figure 70(a), 72(a), and 74(a). The force plot from uncooked tapioca starch and Carbotac at 0.1% is shown in Figure 72. The force curve of Carbotac at 0.25% with cooked natural tapioca starch at 0.05%, cooked cationic tapioca starch (Aquaflocc330T) at 0.05%, and cooked anionic tapioca starch (Aquabloc252T) at 0.05% by the contact mode on AFM are shown in Figure 75, 76, and 77. Nevertheless, some random samples showed an abnormal curve which can be seen in Figure 75(b), 76(b), and 77(b). Two atypical samples showed the unfolding constituents at the tip. Another one showed that the tip had fallen into holes which made them stickier because the surface in the hole touched the sides of the tip. 80

95 (a) (b) Figure 70. The images of Carbotac at 0.25% filmed on the glass slide captured by the tapping mode on AFM, (a) the surface image, (b) the topography image (left) and the phase image (right) 81

96 Figure 71. The force curve of Carbotac at 0.25% by the contact mode on AFM 82

97 (a) (b) Figure 72. The images of films of Carbotac at 0.1% and uncooked tapioca starch at 0.1% captured by the tapping mode on AFM, (a) the surface image, (b) the topography image (left) and the phase image (right) 83

98 Figure 73. The force curve of Carbotac at 0.25% and uncooked tapioca starch at 0.1% by the contact mode on AFM 84

99 (a) (b) Figure 74. The images of films of Carbotac at 0.25% and cooked tapioca starch at 0.05% captured by the tapping mode on AFM, (a) the surface image, (b) the topography image (left) and the phase image (right) 85

100 (a) (b) Figure 75. The force curve of Carbotac at 0.25% and cooked tapioca starch at 0.05% by the contact mode on AFM. There were two plots found from the tests, (a) when it was normal, and (b) when the tip fallen down in holes that made unreliable testing. 86

101 (a) (b) Figure 76. The force curve of Carbotac at 0.25% and cooked anionic tapioca starch (Aquabloc252T) at 0.05% by the contact mode on AFM. There were two plots found from the tests, (a) when it was normal, and (b) when the tip dragged some unfolding components 87

102 (a) (b) Figure 77. The force curve of Carbotac at 0.25% and cooked cationic tapioca starch (Aquaflocc330T) at 0.05% by the contact mode on AFM. There were two plots found from the tests (a) when it was normal, and (b) when the tip dragged some unfolding components AFM Results for Rosin Size (Champion77) : The 3D dimensional surface, the topography image, and the phase image were shown in Figure 78 and 80. The force curve of rosin size (Champion77) at 0.25% is 88

103 presented in Figure 79. The force plot of rosin size alone showed more stickiness compared to adding various kinds of cooked tapioca starches in rosin size as shown in Figures 81, 82, and 83. (a) (b) Figure 78. The images of films of rosin size (Champion77) at 0.25% captured by the tapping mode on AFM, (a) the surface image, (b) the topography image (left) and the phase image (right) 89

104 Figure 79. The force curve of rosin size at 0.25% by the contact mode on AFM 90

105 (a) (b) Figure 80. The images of films of rosin size (Champion77) at 0.25% and cooked tapioca starch at 0.05% captured by the tapping mode on AFM, (a) the surface image, (b) the topography image (left) and the phase image (right) 91

106 Figure 81. The force curve of rosin size at 0.25% and cooked tapioca starch at 0.05% by the contact mode on AFM Figure 82. The force curve of rosin size at 0.25% and cooked anionic tapioca starch (Aquabloc252T) at 0.05% by the contact mode on AFM Figure 83. The force curve of rosin size at 0.25% and cooked cationic tapioca starch (Aquaflocc330T) at 0.05% by the contact mode on AFM 92

107 Cappella and Dietler (1999) described the relation between AFM force-distance curves and tip-sample interaction force and explained that an AFM force-distance curve is a plot of tip-sample interaction forces vs. tip-sample distance. In order to obtain such a plot, the sample (or the tip) is ramped along the vertical axis (Z axis) and the cantilever deflection, δc is acquired. The tip-sample force is given by Hooke s law : F = -k x δc. The spring constant is determined by k. The distance detected during the measurement is not the actual tip-sample distance, D in Figure 84, but the distance Z between sample surface and the rest position of the cantilever. These two distances differ because of cantilever deflection, δc and because of the sample deformation, δs. These four quantities are related as follows: D = Z (δc + δs). Since one does not know in advance the cantilever deflections and the sample deformations, the only distance that one can control is the Z distance, i.e., the displacement of the piezo. Therefore, the raw curve obtained by AFM should be called force-displacement curve rather than force-distance curve. This latter term should be employed only for curves in which the force is plotted versus the true tip-sample distance, that has been previously calculated from raw data. When not referring to the specific type of plot employed, the term force-distance curve is used. 93

108 Figure 84. The tip-sample system. D is the actual tip-sample distance, whereas Z is the distance between the sample and the cantilever rest position. These two distances differ because of the cantilever deflection δc and because of the sample deformation δs The tip-sample force (F) can be calculated from the formula : F = -kx as above. The distance Z (nm/div) between the sample surface and the rest position of the cantilever was 50 nm/div according to the force calibration plot, except for uncooked tapioca starch in Figure 73 which has nm/div. The number of blocks in the plot (div) were counted from the graphs, and then, the distance (X) in nm was calculated for use in the equation. The spring constant or force constant (k) was 0.2 N/m for the contact mode tip used in this experiment. The results are shown in Table 15 below. 94

109 Table 15. The tip-sample interaction force (N) of stickies and tapioca starches by AFM The numbers of block in the plot (div) Force Chemicals 1st 2nd Average (nn) Carbotac 0.25% The force is too high for the spring contant at 0.2 N/m. Carbotac 0.1% and Uncooked Natural Tapioca Starch 0.1% Carbotac 0.25% and Cooked Natural Tapioca Starch 0.05% Carbotac 0.25% and Cooked Anionic Tapioca Starch 0.05% (Aquabloc252T) Carbotac 0.25% and Cooked Cationic Tapioca Starch 0.05% (Aquaflocc330T) Rosin Size 0.25% (Champion77) Rosin Size 0.25% and Cooked Natural Tapioca Starch 0.05% Rosin Size 0.25% and Cooked Anionic Tapioca Starch 0.05% (Aquabloc252T) Rosin Size 0.25% and Cooked Cationic Tapioca Starch 0.05% (Aquaflocc330T) In Table 15, the force from the filmed Carbotac could not be tested because the force was so high that the contact mode tip (k) at 0.2 N/m could not be determined. The highest force measures was for rosin size which was 72 nn. 95

110 DISCUSSION COMPARISON OF EFFECTIVE SOLVENT REAGENTS The results from the experiments obviously show that the ethanol-benzene mixture is more effective for extracting DLK and SCP than using hexane as the solvent. Although hexane was mentioned in Lee & Kim (2006) s article to get a better yield in analyzing the gravimetric amount of extract, only small amounts of DLK extractives were obtained from the experiments in this report. Solvent extraction methods extract a compound by using a solvent whose polarity is close to that of the target compound. Benzene is suitable for aromatic compounds and ethyl acetate is proper for relatively polar compounds. On the other hand, hexane is a non-polar solvent and lipophilic. Recycled pulp is considered to have the polar forces that act in pairs, with opposite tendencies. The ethanol-benzene mixtures would be a better choice in this case. Hexane might need longer times to get high amounts of extractives. Therefore, it is probably not efficient for unstable organic compounds. DECOMPOSITION ANALYSIS OF EXTRACTIVES AND ADHESIVES The recycled pulp (DLK) and the semi-chemical pulp (SCP) mixed with stickies can be examined by TGA. The decomposition temperature evidently shows the different range of temperatures compared to the pulps alone. TGA can be used to identify and study the compositional materials in extractives and deposits. The varied pulp ratios of two types of pulps show the different weight losses. It is supposed that both pulps in this test have dissimilar kinds of components which might be signified as adhesives. 96

111 ASH AND PARTICLE SIZE DISTRIBUTION According to the results from ashing the materials in the muffle furnace, it shows that the pulp fibers of DLK and SCP contain small amounts of fillers which underwent negligible weight change on ignition. Rosin powder and rosin size have inorganic material components in these samples. The mean particle sizes of the uncooked tapioca starches are bigger than the cooked tapioca starch because the water increases the fluidity of starch that adsorbed when the gelatinization takes place. The interaction with water leads to swelling during cooking of the starches. The crystalline structures are broken free and dissolved. Then, it allows the dissolving molecules to disperse in the surrounding water. When Carbotac is mixed with the cooked natural tapioca starch or the cooked anionic tapioca starch, the average particle sizes are diluted the same as Carbotac. Their particle sizes greatly decrease. In contrast, the mean particle size from the mixture of cooked cationic tapioca starch and Carbotac does not decrease heavily like the natural starch and the anionic starch. It can be assumed that an agglomeration is formed in the solution due to the opposite charge between Carbotac and the cationic starch. THE EFFECT OF TAPIOCA STARCH POLYMERS ON STICKIES Emulsion polymers are extensively used to produce pressure-sensitive adhesives (PSAs) for use in the paper industry. Most of the commercial PSAs are negatively charged. Water-dispersible/soluble PSAs have been produced mostly by emulsion polymerization of acrylate and acrylic acid at low ph. The water-soluble PSA used, in this case was Carbotac, which is negatively charged. These types of PSA do not usually 97

112 adsorb onto wood fibers because the majority of cellulosic pulps are also negatively charged. Hence, Carbotac will accumulate in the paper recycling process water and lead to stickies problems in the system. In the case of rosin size as a wood extractive, generally commercial rosin sizes are slightly anionic and the rosin size (Champion77) used in this research has anionic charges as does Carbotac. Thus, it cannot easily adsorb onto the negatively charged fibers which causes the accumulation of anionic material in the papermaking loop. Natural starch has a slight anionic charge because of the existence of acidic groups and oxidized sites. When the anionic rosin size and the anionic Carbotac were blended with the anionic starch polymers, there was no agglomeration occurring due to charge repulsion. When solutions of two oppositely charged species such as cationic charges and anionic charges are mixed, an agglomeration is often formed as shown in the mixture of Carbotac and the cationic starch or rosin size and the cationic starch. This happens because the oppositely charged polymers attract one another and bind together. PEEL STRENGTH ON THE MIXTURE OF STICKIES AND STARCH POLYMERS The outcome from the Instron tack tests show that the peel strength increases with increasing chemical percentages as it should because the stickies would generally give more stickiness if the quantity is increased. Therefore, the tack tester can be used to detect how much adhesive force we can get from each sample. The results show that the tapioca starch and all of its derivatives have strong forces of peel strength themselves with 98

113 stickies absent. The cooked tapioca starches have peel forces higher than the stickies in most cases; however, adding the tapioca starches to the stickies can reduce the adhesive strength in some cases. The natural tapioca starch with Carbotac had increasing peel strength trends when two combinations of starch and stickies were blended together; however, the combination of natural tapioca starch and rosin size shows that the effect from starch itself was greater. The peel strength of anionic tapioca starches with OSA and without OSA mixed with either Carbotac or rosin size behaved similarly. Their peel strength increased continuously when increasing starch concentration. Nonetheless, the peel strength from both kinds of anionic tapioca starch with rosin size tended to decrease after increasing the starch concentration. This tendency happened when mixing with Carbotac, but the peel strength decreased after the starch concentration reached a 0.25% concentration. This overcame the effect of stickiness of starch itself. The peel strength on the cooked cationic tapioca starch and the cooked cationic OSA tapioca starch mixed with Carbotac has maximum peel force when the starch was added at 0.05% concentration. These forces reached maxima at 0.05% and then decreased when the addition of starch increased. Cationic starch tends to have a higher peel strength (kgf) compared to the anionic starch and the natural starch in most of the cases because the opposite charges between the cationic starch and the anionic stickies create an agglomerate which seems to give higher bonding of the cloth strips to the glass slide. In addition, it appears that the effect of OSA does not have much impact on the peel strength because the peel strength of the cationic 99

114 starch and the anionic starch with OSA and without OSA are very similar. The effect of the charges are more important to the peel strength than the presence or absence of OSA. THE TREATED AND UNTREATED SURFACES BY AFM The stickies or untreated samples apparently have the stronger interaction forces examined by AFM. Mixing cooked tapioca starches with the stickies can decrease the interaction forces. Moreover, the surface images of treated samples distinctly show a smoother surface. The treated samples need less force compared with the untreated sample. Some random points found in the mixtures of Carbotac show the presence of stretchy components at the tip which was not observed in the mixtures of rosin size. However, these forces show merely the approximate forces from the random points on the surface of samples. The plots with Carbotac that show existence of the extended or stretched components are not considered in this estimation. The plot from the cooked tapioca starch shows the tip fell down into the holes that made the data unreliable, so this also will not be considered. The non-homogeneous surface is an artifact of AFM technique and does not accurately reflect surface stickiness. However, when the results on AFM are compared to the outcomes from the peel strength test, the results are completely different. The peel strength of the mixture of Carbotac at 0.25% and the cooked tapioca starches at 0.05% has an increasing strength compared to Carbotac alone. On the other hand, the treated samples of the mixtures of Carbotac and the cooked tapioca starches at the same concentration when tested on the AFM show that the treated samples need smaller forces which means that they are less sticky. The same is true with rosin size. This situation is probably because of the methods 100

115 we use. Although the peel strength on the Instron and the force curve on the AFM are related to the adhesive strength that indicates stickiness of each sample, it should be considered that the mechanisms of the methods are different. The peel strength test on the Instron measures the bonding strength acting between the glass slide and the cloth enhanced by the varied solution mixtures. The starch is mostly used for improving bonding strength in papermaking. When the starch is blended with stickies, it creates the bonding forces to attach the cloth to the glass slide. The interaction force measured by the AFM detects the force between the tip and the surface. The particles of stickies on the film might be encapsulated by the starch polymers that make it become less sticky. Thus, the Instron measures bonding force between the cloth and silde, while the AFM is probably a more direct measurement of the stickiness of the surface. 101

116 CONCLUSIONS 1. The ethanol-benzene mixture is a suitable reagent to extract stickies from pulps compared to hexane. 2. The pyrolysis analysis on the thermogravimetric analysis instrument (TGA) can be used as a method for examining the compositions of deposits and sticky materials. 3. The cooked tapioca starches usually have higher peel strength than the stickies. Adding the tapioca starch polymers to the stickies can only help to reduce the peel strength in certain specific cases. 4. The OSA does not have a large effect on the peel strength compared to the charges of the starches, which change bonding behavior. 5. Although the results from Instron and AFM are attempts to measure the stickiness, the mechanisms are different. The peel strength from the Instron is much more a measurement of the bonding strength. The force curve from the AFM meanwhile reveals the adhesive strength on the surface or stickiness. 6. AFM results show that the tapioca starches reduced stickiness and produced smoother surfaces for both Carbotac and rosin size. 102

117 SUGGESTIONS FOR FUTURE WORK The adhesive interaction between sticky deposits and starch polymers is still challenging to research. Nowadays starch polymers are widely used in the wet-end process as an additive to increase the strength of paper. The sticky contaminants from recycled pulps or virgin pulps are always thought to be the reason for stickies agglomeration in the process even though other polymer additives generally used might be one of many reasons leading to the problems. From the results of the report, it is still unclear about the mixture of stickies and starch polymers; whether they add to problems by increasing the bonding strength and increasing the stickiness or help us to reduce the agglomeration by encapsulating the sticky particles and decreasing the stickiness. There are some interesting suggestions for future work as follows; 1. Investigate further OSA substituted starches. 2. Investigate the charge demand chemistry for the various starches and sticky compounds. 3. Investigate treatment with anionic starches and positive ions, particles, or polymers as an additional component. 4. Investigate stabilization of micro-stickies by anionic starches. 103

118 REFERENCES CITED Bai Y. (2008). Preparation and Structure of Octenyl Succinic Anhydride Modified Waxy Maize Starch, Microporous Starch and Maltodextrin, Department of Grain Science and Industry, College of Agriculture Kansas State University. Banerjee S. & Haynes D. (2008). Stickies Control with Cyclodextrins, Peer-Reviewed Tappi Journal, November 2008, 4-7. Barnetoa A.G., Vilab C., & Arizaa J. (2011). Eucalyptus kraft pulp production: Thermogravimetry monitoring, Thermochimica Acta 520, Barreira W., Barreto R.L. & Abouchar M.A. (2010). Chemical Pitch and Stickies Control, XXI Encontro Nacional da Tecnicelpa / VI CIADICYP 2010, Outubro 2010, Lisboa, Portugal. Bemiller J.N. & Whistler R.L. (2009). Starch Chemistry and Technology Third Edition, Food Science and Technology, International Series, 541, , 555, 667. Bittner, M.J. (1994). Stickies Collection and Quantification within a Production Environment, 1994 Pulping Conference, Bruker Nano Surfaces (2012). Fundamentals of Contact Mode and Tapping Mode Atomic Force Microscopy. Retrieved from Cappella B. & Dietler G. (1999). Force-Distance Curve by Atomic Force Microscopy, Surface Science Report 34 (1999), Castro C., Dorris G.M., Brouillette F., & Daneault C. (2003). Thermogravimetric Determination of Synthetic Polymers in Recycled Pulp Systems and Deposits, Journal of Pulp and Paper Science : Vol.29, No.5, May 2003, Cathie, K. (1994). The Effect of Packaging Adhesives on Wastepaper Recycling A Review, INT.J.Adhesion and Adhesives January 1994, Vol.14 No.1, Chen, Q. (1999). Mechanisms of Chemical Agglomeration Operations in the Deinking of Mixed Office Waste. Department of Wood and Paper Science, North Carolina State University. Chavalparit O. & Ongwandee M. (2009). Clean Technology for the Tapioca Starch Industry in Thailand, Journal of Cleaner Production 17 (2009),

119 DeJong R.L., & Pescantin M. (2005). Flotation of Cleaner Rejects Removes High Density Stickies, 2005 Engineering, Pulping & Environmental Conference. Doshi M., Dyer J., Aziz S., Jackson K., & Abubakr S. (1999). Quantification of Micro Stickies, Paper Recycling Challenge-Process Control & Mensuration, August 1999, Doshi, M.R. (2009). A review of stickies Measurement Methods, Progress in Paper Recycling, Second Quarter 2009, Vol. 18, No. 3, Doshi M.R., Blanco A., Dorris G.M., Castro C., Hamann A., Haynes R.D., Houtman C., Scallon K., Putz H., Johansson H. & Venditti R.A. (2003). Comparison of Micro-stickies Measurement Methods Part II: Results and Discussion, Progress in Paper Recycling / Vol. 13, No. 1, November 2003, Food Developer E-source. Starch Modification, Retrieved from Furuta T. & Gray D.G. (1998). Direcr Force-Distance Measurements on Wood-Pulp Fibers in Aqueous Media, Journal of Pulp and Paper Science : Vol.24, No.10, October 1998, Han J., Lee B., Lim W.J. & Lim S. (2005). Utilization of Hydroxypropylated Waxy Rice and Corn Starches in Korean Waxy Rice Cake to Retard Retrogradation, Cereal Chem. 82(1): Haynes, R.D. (2011). Removing the Unknown of Lap Pulp Colloidal Stickies to Improve Paper Machine Runnability, Paper Con 2011, Haynes, R.D. (2012). Colloidal Organic Content and Tackiness of Coated Broke and Recycle Fiber, PEERS Conference 2012, December 1994, Project F Hubbe M.A., Rojas O.J., & Venditti R.A. (2006). Control of Tacky Deposits on Paper Machines - A Review, Nordic Pulp and Paper Research Journal,Vol 21, No. 2/2006, Hubbe, M. (n.d.). Cationic Starch, Mini-Encyclopedia of Papermaking Wet-End Chemistry, Web. 20 Feb < Hubbe, M. (n.d.). Amphoteric Starch, Mini-Encyclopedia of Papermaking Wet-End Chemistry, Web. 20 Feb < 105

120 Huo, X. (2002). Adhesive Contaminants (Stickies) : Characterization and Their Interaction with Papermaking Components During Paper Recycling, Department of Wood and Paper Science, North Carolina State University. Hutten M., Su W., Jeffreys C., & Banerjee S. (1994). Interactions between Stickies and Fiber, Progress Report to The Institute of Paper Science and Technology. Johansson H, Wikman B, Lindström E & Österberg F (2003). Detection and Evaluation of Micro-Stickies. Prog Pap Recycling 12(2): Kambe H., & Kamagata K. (1969). A Method of Measuring Tackiness, Journal of Applied Polymer Science, Vol.13, Lee H.L. & Kim J.M. (2006). Quantification of Macro and Micro-stickies and Their Control by Flotation in OCC Recycling Process, Appita J 59(1), Ling T.F., Hall J.D., & Walker M.M. (1993). Novel Test Method for Evaluating Stickies Deposition Control, Pulp and Paper Canada 1993, 94:12, Maurer, H.W. (2001). Starch and Starch Products in Surface Sizing and Paper Coating, Tappi Press, 33. Maurer, H.W. (2006). Starch and Starch Products for Wet End Application, Tappi Press, 7-8, 13, 19. Miranda R., Balea A., Sanchez de la Blanca E., Carrillo I., & Blanco A. (2008). Identification of Recalcitrant Stickies and Their Sources in Newsprint Production, Ind. Eng. Chem. Res. 2008, 47, Negro C., Blanco A., García-Suarez C., García-Prol M., Miranda R., & Tijero J. (n.d.) Stickies Control A Challenge to Increase Paper Recycling, Department of Chemical Engineering. Complutense University of Madrid, Spain, 1-6. Oliver H., Bangji C., & Samuel S. (2000). A Novel Application of TAPPI T 277 to Determine Macro-stickies Disintegration and Agglomeration in the Recycle Process, 2000 TAPPI Recycling Symposium, Vol.2, Qiang, H.L. (1997). The Common AFM Modes. Retrieved from Rugar D. & Hansma P. (1990). Atomic Force Microscopy, Physics Today, 43(10), 23. Ryan B.J. & Poduska K.M. (2008). Roughness Effects on Contact Angle Measurements, American Journal of Physics 76,

121 Sarja, T. (2007). Measurement, Nature and Removal of Stickies in Deinked Pulp. The Faculty of Technology of the University of Oulu. Sitholé B., & Filion D. (2007). Assessment of Methods for the Measurement of Macro-stickies in Recycled Pulps, Pulp and Paper Research Institute of Canada, 2007 TAPPI 8th Research Forum on Recycling. Sweedmana M.C., Tizzottia M.J., Schäferb C. & Gilberta R.G. (2013). Structure and Physicochemical Properties of Octenyl Succinic Anhydride Modified Starches: A Review, Carbohydrate Polymers 92 (2013), Technical Association of the Pulp and Paper Industry. (2011). Stickies Definition and Classification, TIP Technical Association of the Pulp and Paper Industry, (2012). Moisture in Pulp, Paper and Paperboard, T412 om-11. Technical Association of the Pulp and Paper Industry, (2007). Solvent Extractives of Wood and Pulp, T204 cm-07. Technical Association of the Pulp and Paper Industry, (2012). Ash in Wood, Pulp, Paper and Paperboard: Combustion at 525 C, T211 om-12. Technical Association of the Pulp and Paper Industry, (2012). Ash in Wood, Pulp, Paper and Paperboard: Combustion at 900 C, T413 om-11. Technical Association of the Pulp and Paper Industry, (2010). Surface wettability and absorbency of sheeted materials using an automated contact angle tester, T558 om-10. The American Forest & Paper Association. (2012). Where Recovered Paper Goes. Web. 20 Feb < The American Forest & Paper Association. (2012). Paper & Paperboard Recovery. Web. 20 Feb < The American Forest & Paper Association. (2012). Recovery & use of Old Corrugated Containers (OCC). Web. 20 Feb < Venditti R.A., Bradley L.E., & Hasan J. (2007). The Effects of Adhesive Properties on the Removal of Pressure Sensitive Adhesive Contaminants by Pressure Screens, Progress in Paper Recycling May 2007, Vol.16 Issue 3,

122 Wu J., Xia J., Lei W., & Wang B.P. (2003). Advanced Understanding of Stickiness on Superhydrophobic Surface, Scientific Reports, 3:3268, 1-4. Yan Z., Luo Y., Deng Y. & Schork J. (2003). Water-Soluble/Dispersible Cationic Pressure-Sensitive Adhesives. II. Adhesives from Emulsion Polymerization, Journal of Applied Polymer Science, Vol. 91,

123 APPENDIX 109

124 Appendix A The Moisture Content Table 16. The moisture content of DLK and SCP Type of Pulp SCP DLK Times Beaker, g Beaker + Pulp, g Initial specimen (W1), g Beaker + Pulp (After heating), g Dry specimen (W2), g % Moisture Content % Moisture Content Average Table 17. The moisture content of starch polymers Type of Starch Times Beaker, g Beaker + Starch, g Initial specimen (W1), g Beaker + Starch (After heating), g Dry specimen (W2), g % Moisture Content Avg. % Moisture Content Tapioca Starch Aqua252T Aqua330T Aquajel 65205TO Aquajel 73005TO Avg. % Solid

125 Appendix B The Ash from the Pulps, the Starches, and the Adhesives Table 18. The ash from the pulps, the starches, and the adhesives at 400 o C and 900 o C Table 19. The ashes from the starches and the adhesives at 750 o C and 900 o C 111