Fabrication and characterization of microencapsulated phase change material with low supercooling for thermal energy storage

摘要

Microencapsulated phase change material with a low supercooling degree is one of the increasing important researches as well as industrial application for thermal energy storage. This study develops a novel and low supercooling microencapsulated n-octadecane (MicroC18) with n-octadecyl methacrylate (ODMA)-methacrylic acid (MAA) copolymer as shell using suspension-like polymerization. The fabrication and properties of MicroC18 were characterized by using a field-emission scanning electron microscope (FE-SEM), Fourier transformed infrared spectroscopy (FTIR), particle size distribution analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The MicroC18 with spherical shapes and an average diameter of 1.60-1.68 μm are fabricated. The onset crystallizing temperatures of MicroC18 are only 4 ℃ below that of n-octadecane. The unique copolymer shell has a significant impact on the low supercooling of MicroC18. The n-octadecane in all of the samples crys-talizes by heterogeneous nucleation. The content of n-octadecane in the microcapsules is low; however, the microcapsules still exhibit high enthalpy through the contribution of the shells. At a monomers-octadecane mass ratio is 2∶1, as used in the recipes, the MicroC18 with highest phase change enthalpy was obtained. The temperature of thermal resistant of MicroC18 is approximately 235.6 ℃, which is affected by the thickness of the polymer shell.