Lignin as Renewable and Superior Asphalt Binder Modifier. Complete Address: 2123 TAMU, College Station, TX 77843, USA.

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1 Supplementary Document for Lignin as Renewable and Superior Asphalt Binder Modifier Shangxian Xie abc *, Qiang Li abc *, Pravat Karki d, Fujie Zhou e$, and Joshua S. Yuan abc$ a Synthetic and Systems Biology Innovation Hub, Texas A&M University, College Station, TX 77843, USA b Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA c Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX 77843, USA d Texas A&M Transportation Institute, Texas A&M University, College Station, TX 77843, USA e College of Transportation Engineering, Tongji University, Shanghai, , China *These authors contributed equally. $ For correspondence: fujiezhou@yahoo.com, syuan@tamu.edu; Phone: ; Complete Address: 2123 TAMU, College Station, TX 77843, USA. 1

2 Methods and Materials Lignin Fractionation by Laccase-Mediator System The Kraft lignin (catalog number ) and laccase from Trametes versicolor (catalog number 38429) were both purchased from Sigma-Aldrich (St. Louis, MO, USA). For lignin fractionation, 6% (w/v) of lignin were dissolved in 35 mm phosphate buffer (ph 7.0), and mixed with laccase at 25 mg protein per gram of lignin and 1mM of the 1-hydroxybenzotriazole as mediator for laccase. The mixture was incubated for 24 hours at 50 with a shaking speed of 180 rpm. The solubilized lignin after laccase-mediator fractionation was collected by centrifuging at 10,000 g for 15 min. The insoluble fraction of lignin after fractionation was dried to constant weight in oven at 60. The soluble fraction was then concentrated to lignin material containing 10% of moisture. Lignin Fractionation by Formic Acid/Fenton (Iron Ion and Hydrogen Peroxide) The aforementioned Kraft lignin was used for the lignin depolymerization by formic acid and Fenton reaction combined processing. Fifty gram of Kraft lignin was boiled in 250 ml of formic acid containing 0.65 g of zinc powder for 2 hours in boiling flask connected to a cooling condenser. The sample was then briefly cooled down and 250 ml of 6% H2O2 and 5 ml of 0.1 M FeSO4 were added to create a Fenton reaction condition. The reaction was continued to boil for another hour. The insoluble and soluble lignin after the processing was separated by centrifuging at 10,000 g for 15 min. The insoluble fraction of lignin after fractionation was dried to constant weight in oven at 60. The soluble fraction was concentrated by rotary evaporator to the concentration of 10% lignin. 2

3 Nuclear Magnetic Resonance (NMR) Characterization 13 C NMR characterization was carried out on an Avance III 500 NMR machine with a HCN cryoprobe. All lignin samples were acetylated before the characterization. 1 Acetylated lignin (150 mg) was dissolved in DMSO-d6 (1 ml) and placed in a 5-mm Wilmad NMR tube. Chromium (III) acetylacetone (0.01 M) as a relaxant was added into lignin solution. 2 The methyl peak of DMSOd6 at 39.5 ppm chemical shift was used as internal reference. A 90 o C pulse width, 1.2 s acquisition time, and 1.0 s relaxation time were used. Data were collected with a total of scans. The assignments were listed in Table S1. For semi-quantification, the integration of aromatic region ( ppm) was set as 1, and the frequency of different functional groups were integrated based on the aromatic region and expressed as the number per aromatic ring. Gel Permeation Chromatography (GPC) Analysis GPC analysis was performed on an OMNISEC system (Malvern Instrument Ltd., Houston, TX) with the following operation conditions. For the column, two D6000M columns (Malvern Instrument Ltd., Houston, TX) were connected in series, and the columns temperature was kept at 45 o C during measurement. Dimethylformamide (DMF) was used as eluent and the flow rate was 1.0 ml/min. The injection volume was 100 μl. The UV detector at 280 nm was used. The samples were prepared by dissolving the acetylated lignin in DMF at a concentration of 1 mg/ml. Before injection, each sample was filtrated using a 0.45 μm PTFE membrane filter (VWR, Houston, TX). Calibration curve was made with poly(methyl methacrylate) having different molecular weight. Characterization of Asphalt Binder Temperature Performance Grade Both high- and low- temperature performance grades were determined using standard test methods. The binder was first melt and stirred evenly to make sure that the lignin was uniformly mixed with 3

4 asphalt binder. For high temperature performance grade, AASHTO T315 (DSR test) was used 3, while for low temperature performance grade, AASHTO T313 (BBR test) was used. 4 Briefly, DSR test was conducted on 25 mm diameter specimens to determine the temperatures at which rutting parameters of original binder specimens ( G ) were equal to 1.0, where G* is the shear modulus sinδ of asphalt binder and δ is phase angle. Similarly, BBR test was conducted on long-term aged asphalt beam specimens to determine the temperatures at which relaxation constant (m) and flexural creep stiffness (S) at the 60 seconds of loading were equal to and 300 KPa, respectively. The test results were used to determine the continuous high and low temperature performance grades of selected binders in accordance to AASHTO M320: Standard Specification for Performance-Graded Asphalt Binder. Characterization of Asphalt Binder Aging Resistance To evaluate aging resistance of lignin with modified asphalt binders, we aged each modified and unmodified asphalt binder samples following the AASHTO T We measured G*/sinδ value of each of these samples at 70ºC following the AASHTO T Parameter G*/sinδ represents effective stiffness of asphalt binder, and works as an indicator of rutting resistance. To study the effect of lignin on binder properties, we measured G*/sinδ of both aged and unaged samples of unmodified base binder (containing 0% lignin) and each binder samples that were modified by lignin fractions including 10% KL, 10% KL-L/H-Insol., 10% KL-LH-Sol., 10% KL-FA-Insol, and 10% KL-FA-Sol. For direct comparison, the ratio of aged to unaged was as shown in Figure S2. A higher value of G*/sinδ ratio of aged to unaged suggests the faster aging (or lower aging resistance) and the vice versa. 4

5 Characterization of Asphalt Binder Mechanical and Rheological Properties We conducted frequency sweep tests on unmodified and lignin-modified binders from 0.1 rad/sec to 100 rad/sec. at 60ºC using a dynamic shear rheometer (Malvern Instruments Kinexus Pro rotational rheometer) to determine their mechanical and rheological properties. We conducted these tests on asphalt binder samples that were doped with four different concentrations of raw Kraft lignin (i.e., 3%, 6%, 15% and 30%). For comparison, we also conducted these tests on unmodified base binder. We also conducted these tests on samples that were doped with 3% of biologically processed soluble and insoluble fractions. In-depth descriptions of these tests are available in authors previous works

6 Supplementary Table and Figure Figure S1. 13 C NMR spectra of lignin. (a), Kraft lignin; (b), insoluble fraction of laccase/hbt processed Kraft lignin; (c), soluble fraction of laccase/hbt processed Kraft lignin; (d), insoluble fraction of formic acid/fenton processed Kraft lignin; (e), soluble fraction of formic acid/fenton processed Kraft lignin. 6

7 G*/Sin ratio of aged to unaged Base binder 10% 10%-KL-L/H-Insol. 10%-KL-L/H-Sol. 10%-FA-Insol. 10%-FA-Sol. Figure S2. G*/sinδ ratios of aged and unaged samples for unmodified base binder and modified binders doped with 10% different lignin fractions. KL, Kraft lignin without processing; KL-L/H- Insol, the insoluble fraction of the Kraft lignin after laccase-hbt processing; KL-L/H-Sol, the soluble fraction of the Kraft lignin after laccase-hbt processing; KL-FA-Insol, the insoluble fraction of the Kraft lignin after formic acid/fenton processing; KL-FA-Sol, the soluble fraction of the Kraft lignin after formic acid/fenton processing. 7

8 Shear Modulus (Pa) Effect of Lignin Dosage Loading Frequency (rad/sec) Base binder KL-Raw-3% KL-Raw-6% KL-Raw-15% KL-Raw-30% Figure S3. Mechanical and rheological properties of base asphalt binder and asphalt binders modified with different dosage of Kraft lignin. KL-raw: Kraft lignin without processing. 8

9 Shear Modulus (Pa) Effect of Lignin Modification KL-Raw-3% KL-L/H-Insol.-3% KL-L/H-Sol.-3% Loading Frequency (rad/sec) Figure S4. Mechanical and rheological properties of asphalt binders modified with 3% different lignin. KL, Kraft lignin without processing; KL-L/H-Insol, the insoluble fraction of the Kraft lignin after laccase-hbt processing; KL-L/H-Sol, the soluble fraction of the Kraft lignin after laccase-hbt processing. 9

10 Table S1. Assignments and quantification of functional groups in 13 C NMR spectra Chemical shift (ppm) Assignment Number of moieties per aromatic ring A B C D E Primary aliphatic OH Secondary aliphatic OH Phenolic OH C4 in Ar-COOH Aliphatic region Methoxyl group A, Kraft lignin; B, insoluble fraction of laccase/hbt processed Kraft lignin; C, soluble fraction of laccase/hbt processed Kraft lignin; D, insoluble fraction of formic acid/fenton processed Kraft lignin; E, soluble fraction of formic acid/fenton processed Kraft lignin. 10

11 Reference: 1. Chen, C.-L., Determination of total and aliphatic hydroxyl groups. In Methods in lignin chemistry, Springer: 1992; pp Capanema, E. A.; Balakshin, M. Y.; Kadla, J. F., Quantitative characterization of a hardwood milled wood lignin by nuclear magnetic resonance spectroscopy. Journal of Agricultural and Food Chemistry 2005, 53 (25), AASHTO, T., 315 Standard test method for determining the rheological properties of asphalt binder using a dynamic shear rheometer (DSR). American Association of State Highway and Transportation Officials AASHTO, T., 313 Standard Method of Test for Determining the Flexural Creep Stiffness of Asphalt Binder Using the Bending Beam Rheometer (BBR).. American Association of State Highway and Transportation Officials AASHTO, T., 240 Standard Method of Test for Effect of Heat and Air on a Moving Film of Asphalt (Rolling Thin-Film Oven Test).. American Association of State Highway and Transportation Officials Karki, P.; Zhou, F., Effect of Rejuvenators on Rheological, Chemical, and Aging Properties of Asphalt Binders Containing Recycled Binders. Transportation Research Record: Journal of the Transportation Research Board 2016, (2574), Zhou, F.; Chen, P.; Huang, S.-C., Characteristics of Virgin and Recycled Asphalt Shingle Binder Blends: Rheological and Chemical Properties. Transportation Research Record: Journal of the Transportation Research Board 2014, (2444),