Sugar Alcohol based Materials for Seasonal Storage Applications FP7 project - SAM.SSA Sugar Alcohol based Materials for Seasonal Storage Applications Workshop and Onsite Demonstration CiCenergigune Miñano, Alava, Spain
Microencapsulation of sugar alcohols by different chemical and physical procedures Session 1, Sub Session: 2 Presented by: María Dolores Romero AIDICO. Technological Institute of Construction Contributions by: María Dolores Romero - AIDICO Thomas Ballweg - FhG Radu Piticescu IMNR Roxana Piticescu
Microencapsulation of sugar alcohols by different chemical and physical procedures OUTLINE 1. INTRODUCTION 2. MICROENCAPSULATION OF SA WITH ORGANIC SHELLS (AIDICO) Microencapsulation techniques Main results Conclusions 3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS (IMNR) Description of procedure for microencapsulation Main results Conclusions 4. ENCAPSULATION OF SA WITH HYBRID SHELLS (FhG) Description of procedure for microencapsulation Main results Conclusions
Temperature 1. INTRODUCTION THERMAL ENERGY STORAGE Phase change temperature Latent heat of the phase change Amount of stored heat Thermal Chemical AB + Q A + B A + B AB + Q Heat reaction Sensible heat Latent heat PCMs Heat pumps Liquids Solids Solid-liquid Liquid-gaseous Solid-solid Source: Cryopak website Source: BASF
1. INTRODUCTION PCM: Phase change material Substance able to absorb, store and release energy during the phase change High latent heat Chemically: paraffin wax, ester, fatty acid, hydrated salt PCM: Latent heat storage Source: BASF website Source: PPL products Source: BASF
1. INTRODUCTION Limitations of PCMs PCM: Phase change material Dimensional instability Corrosiveness Low thermal conductivity Compatibility with other materials Leakage Encapsulation Macroencapsulation Microencapsulation Nanoencapsulation Source: PPL products website PCMs in containers (cm) Substances (core materials) introduced in a matrix or shell Source: BASF
1. INTRODUCTION Microencapsulation of PCMs Thermal properties Physical properties Kinetics Chemical properties Economics Proper phase change temperature High latent heat storage Proper thermal conductivity (depending on application) Small volume change during phase change process Low vapor pressure Proper subcooling (depending on application) Crystallization process Long term chemical stability Compatible with container (corrosion) No toxicity No fire risk Available in the market Cost effective for large scale production Source: Cryopak website Source: BASF
1. INTRODUCTION Microencapsulation of PCMs Microencapsulation techniques Particle size, physico-chemical properties of core and shell materials Microparticles Physico-chemical processes Mechanical processes Chemical processes Microcapsules Microspheres Matrix Internal phase Membrane Active principle Source: BASF
1. INTRODUCTION PCMs: Selection of Sugar Alcohol Specifications of Sugar Alcohols : Sugar Alcohol Melting point (ºC) Latent heat (KJ/Kg) Density (Kg/m 3 ) Specific heat (KJ/Kg K) Liquid Solid Liquid Solid Erythritol a 118 354.7 1280 1450 2.66 1.68 Dulcitol b 168-169 401 -- 1466 -- 1.31 D-Mannitol c 165.0 ( ) 338 ( ) -- -- -- -- Xylitol d 93.20 301.12 -- -- -- -- a T. Oya et al. Applied Thermal Engineering 40 (2012) 373-377. b A. Sari et al. Solar Energy 85 (2011) 2061-2071. c C. Telang et al. Pharmaceutical Research 20 (2003) 1939-1945. d A. Biçer, A. Sari Solar Energy Materials & Solar Cells 102 (2012) 125-130.
1. INTRODUCTION Disadvantage of Sugar Alcohols for microencapsulation: Reactivity of hydroxyl group R C Nucleophilic Site C O - + + + H Electrophilic Site Selection of microencapsulation methodology Selection of shell Organic Inorganic Hybrid
2. MICROENCAPSULATION OF SA WITH ORGANIC SHELLS Solvent evaporation P o l y m e r S u r f a c t a n t O i l p h a s e Emulsification R O H S u r f a c t a n t W a t e r S o l v e n t P o l y m e r Sugar Alcohol E v a p o r a t i o n Solvent evaporation The size of nanoparticles can be controlled by adjusting: Stirring rate Type and amount of dispersing agent Evaporation rate Temperature Viscosity of organic and aqueous phases
2. MICROENCAPSULATION OF SA WITH ORGANIC SHELLS Solvent evaporation Solvent/non solvent non solvent H 2 O Solvent evaporation Polymer Surfactant Sugar alcohol O O OH OH D-Mannitol/PMMA Type of surfactant PMMA n HO OH OH D-Mannitol OH Surfactant concentration (1, 3, 5% Span80) Xylitol, dulcitol, erythritol
2. MICROENCAPSULATION OF SA WITH ORGANIC SHELLS Amount of oil phase surfactant Solvent evaporation DSC Sample Tm (ºC) ΔHm (J/g) Tc (ºC) ΔHc (J/g) Mannitol 166 260.1 113.7 194.6 1% 159.7 78.6 99.2 48.0 D-Mannitol/PMMA 3% 157.7 88.5 102.5 40.7 5% 155.6 178.3 105.6 140.8 vs T m D-Mannitol T m α (ºC) 165.5 T m β (ºC) 165.0 T m δ (ºC) 155 Tg (ºC) 10.7 Telang et al. Pharmaceutical Research, 2003, 20, 1939-1945
2. MICROENCAPSULATION OF SA WITH ORGANIC SHELLS Solvent evaporation Amount of oil phase surfactant 1% Oil phase surfactant 3% Oil phase surfactant 5% Oil phase surfactant
2. MICROENCAPSULATION OF SA WITH ORGANIC SHELLS Interfacial polycondensation Oil phase Addition of M2 Oil phase H 2 O Crosslinking reaction at the interface Hydrophilic monomer M1 Hydrophilic compounds Sugar alcohol O C N R' N M2 C O HO R OH or H 2 N R NH 2 M1 C O R O C O O H N R' H N C O Polyurethane n or C O H N R H N C H N R' H N C O Polyurea O n
2. MICROENCAPSULATION OF SA WITH ORGANIC SHELLS Interfacial polycondensation Microcapsules properties (size, morphology, etc.) depend on: Type and amount of surfactant (-NH or OH functionalities) Type of isocianate Isocianate/ROH ratio Surfactant: Lubrizol Amino-functionalized Able to react with TDI 1, 3 and 5 wt% NCO NCO HO OH OH OH OH OH TDI D-Mannitol
2. MICROENCAPSULATION OF SA WITH ORGANIC SHELLS Interfacial polycondensation ROH/TDI = 1/1 D-Mannitol microspheres 1% surfactant 3% surfactant 5% surfactant
T T T Heat Flow (J/g) T 2. MICROENCAPSULATION OF SA WITH ORGANIC SHELLS Surfactant concentration Interfacial polycondensation ROH/TDI = 1/1 D-Mannitol microspheres 5% 1.0 0.5 0.5 1.0 3% 0.5 1% TDI 1.0 0.5 80 T 100 60 2000 Wavenumber (cm -1 ) 4 3 2 1 0-1 -2-3 -4 20 40 60 80 100 120 140 160 180 200 Temperature (ºC) 5% surfactant 3% surfactant 1% surfactant
Heat flow (W/g) Heat flow (W/g) 2. MICROENCAPSULATION OF SA WITH ORGANIC SHELLS Interfacial polycondensation AIR NITROGEN 25 20 20 15 10 5 D-Mannitol - Cycle 1-AIR D-Mannitol - Cycle 30 - AIR 5% Surfactant - Cycle 1 - AIR 5% surfactant - Cycle 30 - AIR 15 10 5 D-Mannitol - Cycle 1 - N2 D-Mannitol - Cycle 30 - N2 5% surfactant - Cycle 1 - N2 5% surfactant - Cycle 30 - N2 0 0-5 -10-5 -15 20 40 60 80 100 120 140 160 180 200 Temperature (ºC) -10 20 40 60 80 100 120 140 160 180 200 Temperature (ºC)
2. MICROENCAPSULATION OF SA WITH ORGANIC SHELLS Interfacial polycondensation - Conclusions Polyurethane and polyurea bonds can be formed between the OH or NH 2 of the surfactant and the isocianate -OH containing surfactant is not a good solution (reaction between isocianate and D-Mannitol is also produced). A different surfactant with different chemical groups, competing with OH from sugar alcohol is required to react with TDI The decrease of thermal energy storage capacity is not only due to the oxidation by the air, but also the temperature increase in thermal cycles, which favors the reaction between the prepolymer and the sugar alcohol: -OH of the SA react with the polymer when increasing temperature during thermal cycles This effect has been produced both in D-Mannitol and Erythritol, which have different melting and crystallization temperatures and also different chemical structure and number of OH groups Although it is possible to obtain sugar alcohols microcapsules by interfacial polycondensation, thermal stability of the capsules during thermal cycling can be improved by studying how to finish the reaction of the prepolymer
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS SOL-GEL SiO 2 as TEOS. Mannitol in spheres from spray drying TEOS D-Mannitol in benzyl alcohol SiO 2 as TEOS D-Mannitol as spheres from spray drying (not dissolution, but dispersion) Water-free process. Hydrolysis of TEOS with benzyl alcohol D-Mannitol : TEOS = 1 : 1 and 1 : 3 (wt)
Abs Abs 3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS SOL-GEL SiO 2 as TEOS. Mannitol in spheres from spray drying 1.5 1.0 0.5 3284 2970 D-Mannitol from spray drying 1424 2909 1641 1086 1287 1019 700 888 632 0.0 0.10 0.08 0.06 0.04 0.02 3302 3029 Encapsulations with SiO2 1496 2871 1451 1007 1208 1086 732 700 D-Mannitol SiO 2-0.00 2000 Wavenumber (cm -1 )
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS SOL-GEL SiO 2 as TEOS. Mannitol in spheres from spray drying D-Mannitol from spray drying Encapsulations with SiO 2
Heat flow (W/g) 3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS SOL-GEL SiO 2 as TEOS. Mannitol in spheres from spray drying 30 25 20 15 10 5 0-5 -10 D-Mannitol Spray drying D-Mannitol:TEOS = 1:1 (wt) D-Mannitol:TEOS = 1:3 (wt) 0 50 100 150 200 Temperature (ºC) DSC air atmosphere D-Mannitol spray drying Encapsulation with SiO 2 (1:1) Encapsulation with SiO 2 (1:3) Tm (ºC) ΔHm (J/g) Tc (ºC) ΔHc (J/g) 167.0 260.9 117.6 204.0 163.6 67.6 106.5 57.7 163.8 84.9 107.9 70.6
Heat flow (W/g) Heat flow (W/g) 3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS SOL-GEL SiO 2 as TEOS. Mannitol in spheres from spray drying 5 4 3 2 1 Mannitol:TEOS = 1:1 Cycle 1. Melting Cycle 1. Crystallization Cycle 10. Melting Cycle 10. Crystallization Cycle 20. Melting Cycle 20. Crystallization Cycle 30. Melting Cycle 30. Crystallization 8 6 4 2 Mannitol:TEOS = 1:3 Cycle 1. Melting Cycle 1. Crystallization Cycle 10. Melting Cycle 10. Crystallization Cycle 20. Melting Cycle 20. Crystallization Cycle 30. Melting Cycle 30. Crystallization 0 0-1 -2-2 -3 0 20 40 60 80 100 120 140 160 180 200 Temperature (ºC) -4 0 20 40 60 80 100 120 140 160 180 200 Temperature (ºC) Thermal cycle 1 Thermal cycle 30
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS SOL-GEL SiO 2 as TEOS. Mannitol in spheres from spray drying a) b) c)
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS SOL-GEL - TiO 2. Mannitol dispersed in organic solvent: avoid water Ti precursor Benzyl alcohol -OH groups D-Mannitol (spheres from spray drying) -OH groups Hydrolysis of Ti Orange solution: Ti compounds
Heat flow (W/g) 3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS SOL-GEL - TiO 2. Mannitol dispersed in organic solvent: avoid water 25 20 15 10 5 Heating D-Mannitol Cooling D-Mannitol Heating - Encapsulation with TiO2 Cooling - Encapsulation with TiO2 DSC air atmosphere 0-5 -10-15 0 50 100 150 200 Temperature (ºC) Tm (ºC) ΔHm (J/g) Tc (ºC) ΔHc (J/g) D-Mannitol 166.0 260.1 113.7 194.6 Encapsulation with TiO 2 166.4 239.0 120.4 179.9
Heat flow (W/g) 3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS SOL-GEL - TiO 2. Mannitol dispersed in organic solvent: avoid water 25 D-Mannitol - Cycle 1 - N2 20 D-Mannitol - Cycle 30 - N2 15 Encapsulation - Cycle 1 - N2 Encapsulation - Cycle 30 - N2 10 5 0-5 -10 0 50 100 150 200 Temperature (ºC) D-Mannitol Encapsulations with TiO 2 Tm (ºC) ΔHm (J/g) Tc (ºC) ΔHc (J/g) Cycle 1 165.2 202.0 112.7 106.2 Cycle 30 165.6 202.1 115.1 152.6 Tm (ºC) ΔHm (J/g) Tc (ºC) ΔHc (J/g) Cycle 1 166.0 209.9 120.7 157.4 Cycle 30 166.6 195.5 124.4 161.6
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS SOL-GEL - TiO 2. Mannitol dispersed in organic solvent: avoid water Tª = 30 ºC Tª = 105 ºC Tª = 160 ºC Tª = 167 ºC Tª = 183 ºC Tª = 30 ºC
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS SOL-GEL SiO 2 CONCLUSIONS - SiO 2 particles do not anchor with the D-Mannitol, as the sugar alcohol stays with the aqueous phase - Hydrolysis of SiO 2 has to be done in water-free process - Microencapsulation of D-Mannitol seems to be suitable by sol-gel procedures in water-free processes TiO 2 - By using aqueous solutions of Mannitol, hydrolysis of TiO 2 is produced, but Mannitol is removed with the aqueous phase - Water free process required - Possible procedure for encapsulations with TiO 2 (heat storage capacity, subcooling, durability under thermal cycles). Deeper analysis is being currently done.
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS OBJECTIVES HYDROTHERMAL / SOLVOTHERMAL Elaboration of a hydrothermal /solvothermal process to encapsulate sugar alcohols in zinc oxide shell as an alternative to the chemical process of simple or complex coacervation Investigate the influence of pressure on the formation of ZnO-sugar alcohols composites (crystal growth process, crystallisation, crystal shape and morphology) RESULTS Preparation and characterization of core/shell structures based on mannitol and ZnO Mathematical model of ZnO-Mannitol hydrothermal synthesis process at high pressures Preparation and characterization of core/shell structures based on erythritol and ZnO
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS Water soluble Zn salt Spray dried S.A. Synthesis pressure: 100 3000 bar T < 100 deg.c Characterization methods: S-A encapsulated in ZnO nanomatrices - Chemical analysis: ICP-OES (Agilent Technology) - Particle sizes, Zeta Potential: Malvern ZS 90 - XRD (Brucker D8 Advance) - FT-IR (ABB) - SEM: HITACHI S2600N (Centre 3MN) - Thermal analysis: DSC Netzch F3 Maya DSC-TG Setsys Setaram
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS Micro-encapsulation of D-Mannitol in ZnO nanomatrices DSC-TG curve for ZnO M8-1 (ZnO : mannitol =10:1), P=100 bar SEM of ZnO 10:1 (P=100 bar)
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS Micro-encapsulation of D-Mannitol in ZnO nanomatrices SEM ZnO :Mannitol 4:1, P=1000 bar) DSC-TG curve for ZnO : mannitol = 4:1, P=1000 bar
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS Micro-encapsulation of D-Mannitol in ZnO nanomatrices FT-IR spectra for ZnO : mannitol = 4:1, P=1000 bar
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS Micro-encapsulation of D-Mannitol in ZnO nanomatrices DSC-TG curve and SEM for ZnO : mannitol = 4:1, P=3000 bar
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS Micro-encapsulation of D-Mannitol in ZnO nanomatrices FT-IR curve for ZnO : mannitol = 4:1, P=3000 bar
T [%] 3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS Micro-encapsulation of Erythritol in ZnO nanomatrices 100 90 erythritol ZnO-Er2 80 70 60 50 40 30 20 10 4000 3500 3000 2500 2000 1500 1000 500 Wavenumber [cm -1 ] FT-IR of ZnO-Er2 sample (ZnO:erythritol=4:1,100 atm.) SEM of ZnO-Er2 sample (ZnO:erythritol=4:1, 100 atm.) Succesful encapsulation clear observed.
3. MICROENCAPSULATION OF SA WITH INORGANIC SHELLS CONCLUSIONS Innovation with respect to the state of the art: Hydrothermal / solvothermal process is used to encapsulate sugar alcohols (Dmannitol and Erythritol) in ZnO shell as an alternative to the chemical process of simple or complex coacervation. Hydrothermal / solvothermal synthesis advantages: the possibility to work at low temperatures (<100 0 C) and high pressures ( 100-3000 atm), single, one step process, controlled composition, morphology and microstructure. ZnO nano was selected due to its versatility and compatibility with SA (in particular D-mannitol or erythritol) Modelling of the encapsulation process of mannitol in ZnO shell by hydrothermal process at pressures between 100 and 3000 atm, revealed that 1000 atm is enough for obtaining a good encapsulation degree. Improved handling and good thermal stability in the final product expected.
4. ENCAPSULATION OF SA WITH HYBRID POLYMERS Encapsulation by Way of UV-curable Hybridpolymeric and Monomeric Building Blocks Principle Vibration assisted microdrop generation through a concentric nozzle combination Cold UV-curing with short residence time in the radiation field ( < 1/10 s) Encapsulation of sugar alcohol supersaturated aqueous solutions or sugar alcohol melts ring nozzle core material shell material UV-curing collector Scheme of the encapsulation process Participants: Thomas Ballweg, Doris Hanselmann
4. ENCAPSULATION OF SA WITH HYBRID POLYMERS Encapsulation by Way of UV-curable Hybridpolymeric and Monomeric Building Blocks General Properties Capsules size range: 0.5 5 mm Adjustable wall thickness Monomodal size distribution Core-shell-type morphology Transparency of the shell allowing the visual control of the physical condition of the sugar alcohol High speed photographs of the encapsulation process showing the vibration assisted drop generation
4. ENCAPSULATION OF SA WITH HYBRID POLYMERS Capsule Quality and Wall Thickness Control Core:Shell ratio = 5:1 Core:Shell ratio = 2:1 High capsule quality and good wall thickness control attainable
4. ENCAPSULATION OF SA WITH HYBRID POLYMERS Monomeric Di- and Trifunctional Monomeric and Hybrid Polymeric Building Blocks for High Strength Shells Urethanedioldimethacrylate (UDMA) Trimethylpropanetriacrylate (TMPTA) Trimethacrylato- (3-mercaptopropyl)methyldimethoxysilane
4. ENCAPSULATION OF SA WITH HYBRID POLYMERS Encapsulation of Xylitol-Erythritol Eutectic Melt by 2-Stage Curing Process-related challenges solved by means of 2-stage curing of acrylate-methacrylate based shell material combinations Xylitol-Erythritol-filled Capsules before and after crystallisation
4. ENCAPSULATION OF SA WITH HYBRID POLYMERS On the Destructive Power of Sugar Alcohol Crystallisation Process-related challenges solved., but crystallization-related challenges remained 5 MPa uniaxial pressure resistance isn t enough to withstand crystallization forces ca. 5 MPa (50 bar) Typical crystallisation-induced defects Images: Fraunhofer
4. ENCAPSULATION OF SA WITH HYBRID POLYMERS Elastomeric Shell Material Alternatives for Sugar Alcohol Encapsulation Composition: 1 : 2 Capsule Size: 3,0 0,1 mm Compr. Strength: 20,7 2,1 N Deform. at break: 54,5 1,5 %
4. ENCAPSULATION OF SA WITH HYBRID POLYMERS Integration of Nucleation Promoters Motivation: MASA-modifications for short time cycling (day-night) application Running MASA-PCMs in the not-subcooling mode Results: Integration of encapsulation-compatible trigger mechanisms possible Low acceleration of crystallization Particles Solvents Gas bubbles
4. ENCAPSULATION OF SA WITH HYBRID POLYMERS Conclusions and Outlook Encapsulation of sugar alcohols melts by means of vibration assisted microdrop generation and UV-curing successfully realized Capsule size in the mm-range complementary to true microencapsulation Monomodal size distribution with controllable wall thickness Core-shell-type morphology Building blocks for high strength and flexible elastomeric shells applicable Integration of nucleating agents (particles, solvents, gas bubbles) demonstrated Outlook Optimization of thermo-chemical & mechanical stability at cycling Further development of nucleation agents for promoting short time cycling Increase of the processing temperature beyond 120 C
The SAM.SSA The SAM.SSA project project Thank you very much for your attention