Microencapsulated phase change materials (MicroPCMs) were prepared using paraffin as core
methyl methacrylate (MMA) and acrylic acid (AA) copolymer as shell
and nanosilica as modifier via in situ polymerization.The effects of the nanosilica on the properties of the MicroPCMs were investigated.The MicroPCMs were characterized by Fourier transform infrared spectroscopy (FTIR)
scanning electron microscopy (SEM)
differential scanning calorimetry (DSC) and thermogravimetry (TGA).The results show that the nanosilica effectively improves the thermostability of the MicroPCMs.The MicroPCMs modified by 3 wt% nanosilica present smooth and spherical morphology with the diameter of 250~300 nm.The MicroPCMs have a high latent heat of 134.79 J/g and the degradation temperature is obviously increased by 40 K in comparison with that of the unmodified MicroPCMs
and the paraffin leakage rate of the modified MicroPCMs is only 2.96% after 1000 times thermal cycling test.