Study On Controllable Preparation And Heat Storage Mechanism Of Paraffin@SiO₂ Phase Change Materials

Traditional organic solid-liquid phase change materials have the problems of low latent heat and easy leakage,which limit the practical application of phase change materials to a certain extent.The encapsulation technology uses organic phase change material as heat storage core material and polymer or inorganic oxide as shell to prepare new type heat storage material with core-shell structure,which solves the limitation of phase change material application and improves the stability of use.In this paper,paraffin was used as phase change material and SiO₂ which produced by hydrolysis and polycondensation reaction of tetraethyl orthosilicate(TEOS)was used as wall material to synthesize the composite phase change material with controllable particle size,high latent heat and strong stability.(1)Using Tween-80,CTAB or a mixture of the two as surfactants,under the same synthesis conditions,the PA@SiO₂ composite phase change material was synthesized.The structure and heat storage performance of the composite were characterized by Scanning Electron Microscopy(SEM),Fourier Transform Infrared Spectrometer(FT-IR)and Differential Scanning Calorimetry(DSC).The results show that paraffin can be successfully coated with the SiO₂ shell.The phase transition temperature and latent heat of PA@SiO₂-C,PA@SiO₂-T,PA@SiO₂-TC are 39.6? and 165.50 J/g,40.5? and 86.54 J/g,41.6? and 84.61 J/g.The encapsulation rates are 44.28%,84.16%,43.29%,respectively.(2)In the acid reaction system,the effect of the amount of TEOS on paraffin@SiO₂-S was investigated.The structural composition,microstructure and thermal properties of the composite phase change materials were analyzed by SEM,FTIR,DSC,TG and thermal cycle experiments.The results showed that when the addition amount of TEOS was 7.5 mL,the phase transition temperature and latent heat of PCM-S3 were 38.8? and 172.35 J/g,while the encapsulation efficiency was about 88.23%.(3)In the alkaline reaction system,the effect of TEOS dosage on PA@SiO₂-J was analyzed.The results were characterized by SEM,FTIR,DSC,TG and thermal cycle experiment.The results indicated that the size of PCM generated in alkaline reaction system was smaller and the content of paraffin was slightly lower.PCM-J2 with TEOS dosage of 6 mL had the best thermal properties.The temperature and latent heat of the phase change were 41.6? and 84.61 J/g,and it has good thermal reliability.