Preparation And Application Of Shape-stable Polymer Phase Change Materials And Their Composite Fibers

Phase change materials(PCMs) are green,reusable energy storage materials.PCMs are widely applied in many fields,however,there are not many selectable PCMs.Because the melting temperature of n-alkyl acrylate copolymer is adjustable by controlling the side-chain length,the appropriate melting temperature can be achieved.The increase of one carbon atom in the side chain of acrylate results in the increase or decrease of 3～6°C,while the copolymerization of acrylates with different carbon atom number in the side chain may realize the continuous change of the phase transition temperature.In order to overcome the leakage disadvantage of acrylate copolymers,GO and metal-organic frameworks were selected as the supporting materials in this study.Shape-stable phase change material of n-alkyl acrylate copolymers prepared by introducing physical cross-linking agent and electrospinning core-spun yarn thermo-regulated fibers were also studied.The main contents are summarized as follows:(1)Poly(tetradecyl acrylate-co-hexadecyl acrylate)(P(TDA-co-HDA))with a molar ratio of 1:1 and SPCMs were fabricated via an atom transfer radical polymerization(ATRP)method and a solution blending method with P(TDA-co-HDA)as a thermal storage material and graphene oxide(GO)as a supporting substance.In this composite,a SPCM was achieved,which absorbed heat at 29.9°C and released it at 12.1°C with a heat storage capacity of 70 J/g at a mass ratio of GO of 10%.The material retained its shape without any leakage at 60°C,which was much higher than that of the melting temperature of P(TDA-co-HDA).(2)Tetradecyl acrylate-hydroxyethyl acrylate-hexadecyl acrylate copolymer SSPCMs were prepared by suspension polymerization.With the increase of HEA mass fraction,this SSPCMs would produce a large number of hydrogen bonds,forming a loose physical structure.A SSPCMs was achieved,which absorbed heat at44.1°C and released it at 22.1°C with a heat storage capacity of 80 J/g at a mass ratio of HEA of 5%.The material retained its shape without any leakage at 60°C,which was much higher than that of the melting temperature of P(TDA-co-HDA).It has a good adsorption capacity for kerosene,and its adsorption capacity for trichloroethylene is higher than toluene.(3)A novel strategy based on metal-organic frameworks nanoparticles(MOFs NPs)-stabilized suspension polymerization has been achieved for the fabrication of multifunctional ZIF-8/P(TDA-co-HDA)and PB/P(TDA-co-HDA)composites.ZIF-8/P(TDA-co-HDA)and PB/P(TDA-co-HDA)absorbed heat at 37.5°C,39.1°C and released it at 8.4°C,10.1°C with heat storage capacity of 63 J/g and 68 J/g,respectively.The material retains its shape without any leakage at 60°C,which is higher than that of the melting temperature of P(TDA-co-HDA).(4)Nanofibers with different concentrations of P(TDA-co-HDA)(molar ratio: 1:1)as core material were successfully prepared by coaxial electrostatic spinning technology and the fibers had obvious sheath/core structure.Coaxial electrostatic spinning technology was further used to fabricate core-spun yarns using P(TDA-co-HDA)and P(TDA-co-HDA)added graphene as core materials and P(AN-co-VDC)as sheath to wrap modified poly(ethylene terephthalate)(PET)/poly(hexadecyl acrylate)(PHDA)thermo-regulated filaments.The core yarns were completely wrapped by nanofibers and the enthalpy value are all about 25 J/g.The yarns can significantly increase the static air adsorption capacity.Therefore,it is helpful to improve the thermal insulation performance and prolong the temperature regulating period of time,which was proved by the infrared photos.