Properties Of Chitosan/PEG New Kind Of Polymeric Solid-solid Phase Change Materials

Recently, the phase change materials(PCMs) have been a popular concern international subject in the application of energy and material science. The application is very wide, such as the thermal energy recovery, building, heat preservation clothing. With the advantage of no need to seal them and without the liquid leakage problem during the phase change process, the polymeric solid-solid phase change materials are one of the promising function materials, with high thermal heat storage ability and excellent mechanical property, easily moulding.There are three parts in this paper. Firstly, the graft copolymerization method was used. The flexible polymer methoxypolyethylene glycol(MPEG) served as functional branch chain, with which the energy storage and energy release can be proceeded by phase transition between its crystal state and amorphous state, and the rigid polymer chitosan served as skeleton, which can ensure the solid-nature of phase change materials during the phase transition.FT-IR, DSC and TGA were used to analyze the structure characteristics and phase change properties, respectively. Results demonstrated that thermal stability of the phase change materials was good and the phase transitions were reversible. The phase change enthalpy can be up to95.22J/g, increasing10%at least. The phase change enthalpy and phase change temperature had relationship with molecular weight and contents of MPEG. Because of the good dissolubility of the chitosan-g-PEG, it can be dissolved in organic solvent such as acetone, DMF and DMSO, which was benefit for the further application.Secondly, the phase change properties of PEG/chitosan was prepared by chemical reactions and its blending were studied. The results showed that the blending materials were the shape-stabilized solid-liquid PCMs for the migration of PEG after a long time, but the PCMs prepared by chemical bonding were solid-solid PCMs. By the way of blending, both the enthalpy and the transition temperature of the materials were higher than those of chemical bonding materials, but the thermal stability of chemical bonding materials was better.Thirdly, a new blending method was introduced to prepare novel solid-solid phase change materials through PEG blending grafted polymer chitosan-g-PEG. By the way of changing the blending polymer proportion, the phase change enthalpy and temperature can be adjusted. And from the results, to keep the solid-solid phase change, the chitosan-g-PEG5000 system had larger mass than the chitosan-g-PEG2000system with the same PEG concentration.