Non-isothermal crystallization behavior of polyethylene glycol/expanded vermiculite form-stable composite phase change material

Abstract

In this work, non-isothermal crystallization behavior of polyethylene glycol (PEG)/expanded vermiculite (EVM) form-stable composite phase change material (PEG-EVM) was investigated. The activation energy of non-isothermal crystallization of PEG-EVM (−219.7 kJ/mol) was lower than that of PEG (−375.3 kJ/mol), indicating that the energy barrier of heterogeneous nucleation decreased, demonstrating that the EVM significantly accelerated the nucleation of PEG. However, the crystallization kinetic parameters (half-crystallization time, crystallization rate and required cooling rate for a designated relative crystallinity) revealed that the non-isothermal crystalline growth of PEG in PEG-EVM was constrained because the surface interactions of EVM hindered the migration and diffusion of PEG molecular chains to the surface of nucleus.