Synthesis And Properties Of WPU/NANO-ZnO Phase Change Materials

In this paper, a series of WPU/nano-ZnO phase change materials with PBA-based soft segment and isophorne diisocyanate (IPDI), dimethylol propionic acid (DMPA)-based hard segments was synthesized by anionic self-emulsified method. The effects of modification of nano-ZnO, the addition method of nano-ZnO, the content of nano-ZnO, the molar ratio of NCO/OH, the amount of DMPA on the basic properties of WPU/nano-ZnO phase change materials were discussed. DSC, POM, SEM and electronic tensile machine were used to study phase change behavior, the crystalline morphology, the morphology structure, and mechanical properties. Then the best formula could be obtained.We could get the following results in the study of the properties of WPU/nano-ZnO composite emulsion. The increasing of nano-ZnO content resulted in that the particle size kept rising and the viscosity went down for composite emulsion. With the increase of the molar ratio of NCO/OH, the particle size of polyurethane composite emulsion increased. However, the viscosity of composite emulsion decreased at first and then increased. With increasing the amount of DMPA, the viscosity of composite emulsion increased while the particle size declined.In the study of the properties of WPU/nano-ZnO phase change materials, the following research results were obtained:After the modified nano-ZnO was added into the WPU system, the enthalpy, tensile properties and the water resistance of phase change materials improved a lot. Phase change materials obtained by adding nano-ZnO in reaction process had a better property in enthalpy and tensile than that in hydration process.The increasing of nano-ZnO content made the crystallization, tensile properties and the water resistance all increase gradually in the beginning and decline finally, and the spherulite radius decrease slowly at first, and then increase.When the content of nano-ZnO was 0.45wt%, the crystallization, tensile properties and the water resistance of phase change materials were the best, and the spherulite radius reached the minimum. With the increase of the molar ratio of NCO/OH, the enthalpy and the enlongation at break decreased, but the tensile strength of phase change materials enlarged at the beginning and then decreased. The water resistance increased with the increase of the molar ratio of NCO/OH. With increasing the amount of DMPA, the tensile strength of phase change materials went up. but the enlongation at break declined, the water resistance decreased.The above results indicated that the best formula of WPU/nano-ZnO phase change materials with PBA-based soft segments and IPDI-based hard segments was as follows:the amount of nano-ZnO was 0.45 wt%, the value of R ([NCO]/[OH]) was 1.8, the amount of DMPA was 5.4wt%.