Study On Wasted Polystyrene Used As Shell In Paraffin Wax Microencapsulated Phase Change Materials

Polystyrene is now widely used in architecture and packaging,etc..The polystyrene production in China has been ranked in the forefront of the world.However,polystyrene is usually made into disposable products which cause serious wastes.Polystyrene has good corrosion resistance and aging resistance and it is difficult to be degraded,which causes serious "white pollution".Therefore,the recycling of wasted polystyrene is an important issue to be settled urgently all over the world.Phase change material(PCM)is used to store or release heat during phase transition process.The solid-liquid PCM is mostly used at the present stage.Vacuum absorption and microencapsulation method are usually used during the preparation in order to prevent the material from leaking during the phase change process.Polystyrene is often used as the shell material of the microencapsulated PCM,but the shell is usually prepared by polymerization with styrene and recycling of wasted polystyrene as shell material has not been reported.In this study,the environmental friendly was taken into consideration.Preparation of PCM with phase separation method based on wasted polystyrene and paraffin wax was carried out.The organic solvent can be recycled.The cost was reduced and the process was simplified without using styrene monomer.The main finished study was listed below:1.We recycled wasted polystyrene by phase separation method to prepare paraffin wax / wasted polystyrene microencapsulated phase change material and studied the influence of stirring speed,the concentration of surfactant,core-shell ratio,oil-water ratio and heating methods.Then we chose a group of excellent conditions to prepare the material and characterized it with SEM,FT-IR,TGA and DTA and did some leakage tests.The results showed the wasted polystyrene shell prevent the core from leaking during the phase transition process and the latent heat of the material was significantly promoted to 72.52 J/g in comparison with others.2.Using wasted polystyrene and polycarbonate as shell materials,paraffin wax /wasted polystyrene-polycarbonate microencapsulated phase change material was prepared.It was characterized by SEM,FT-IR,TGA and DTA.Leakage and thermalconductivity tests were also done.The results showed the polycarbonate could promote the thermal conductivity of the shell and nearly no leakage can be found.The fold structure of polycarbonate was found through SEM,which was good for heat transfer.3.Using wasted polystyrene and graphite as shell materials,paraffin wax / wasted polystyrene-graphite microencapsulated phase change material was prepared.It was characterized by SEM,TGA and DTA.Leakage and thermal conductivity tests were also done.The results showed the preparation of paraffin wax / wasted polystyrene-graphite PCM by phase separation method overcame the polymerization inhibition of graphite during the styrene polymerization process thus the content of graphite was improved.The thermal conductivity was improved from 0.074 W/mK of wasted polystyrene to 0.113 W/mK.