Preparation And Proerties Of Nano TiO₂/Network Polyurethane Phase Change Microcapsules

In recent years,with the increase of energy use,the phenomenon of environmental pollution and resource waste is particularly serious.The phase change materials can rationalize the utilization of energy and solve the problem of energy waste,but phase change materials cannot be used directly because of their own defects in physical properties,so they need to be encapsulated by microencapsulation technology.In this paper,using butyl stearate as the core material and isophorone diisocyanate?IPDI?and glycerol as the reaction monomers,a network polyurethane phase change microcapsules was prepared by interfacial polymerization.The effects of the kinds of emulsifiers,the mass ratio of monomers,the reaction temperature and other conditions on the clad ratio and morphology of the microcapsules were studied and find out the optimal process conditions.Subsequently,the nano TiO₂ modified by KH550 was added to the wall material to prepare composite network polyurethane phase change microcapsules.The effect of the amount of nanoparticles on the thermal stability,enthalpy of phase change,and surface morphology of the phase change microcapsules was studied,and finally,the optimal dosage of nano TiO₂ was determined.According to the clad ratio and surface morphology of microcapsules,the optimal process conditions for preparing network polyurethane phase change microcapsules were determined:The best emulsifier was the compound emulsifier of styrene-maleic anhydride copolymer?SMA?and sodium lauryl sulfate?SDS?,and the HLB required to emulsify butyl stearate was 20.8.The amount of emulsifier is 12.5%,the monomer mass ratio to synthesize wall materials is 1:3?IPDI:glycerol?,the reaction temperature is 60?,the wall to core mass ratio is 1:3.5,and the emulsification speed is 750 r/min.The characteristic peaks of the infrared spectrum show that the microcapsules contain the structure of polyurethane and butyl stearate,and the microcapsules are observed as spherical particles through a microscope.TG and DSC test results show that the decomposition temperature of the microcapsules is between 280?295?,and the phase change enthalpy is 20.52 J/g.The average particle size of microcapsules is 14.08?m,and the most microcapsules'particle size distribution of are in the range of 6 to 22.4?m.The addition of TiO₂ will increase the thermal performance of the microcapsules first and then decrease,and the optimal amount is 0.4%.The thermal stability of the composite microcapsule is slightly improved,the phase change enthalpy is 22.02 J/g,and it has good heat storage performance.The microcapsules modified by TiO₂ have the characteristics of photocatalysis and UV resistance,which can be used in photocatalytic degradation of dyes and UV protective coating...