Preparation and characterization of polyethylene glycol/unsaturated polyester resin composites as phase change materials for thermal energy storage

A novel melt blending method was adopted to prepare polyethylene glycol(PEG)/unsaturated polyester resin (UPR) composites as shape-stabilized phase change materials (PEG/UPR SS-PCMs) with various PEG mass fractions for thermal energy storage. In SS-PCMs, PEG serves as latent heat storage material and silica gel acts as supporting material to keep the stable shape of the composites during the phase transition. The thermal property, thermal stability, chemical structure, the physical and chemical action between the components of the SS-PCMs and crystallization properties of SS-PCMs were studied by DSC, TG, XRD and FT-IR. Results show that the terminal hydroxy groups of PEG respectively enter into addition reaction and intermolecular dehydration reaction with the carbon-carbon double bond and the terminal hydroxy groups or terminal carboxyl groups of UPR or cured UPR, and thus produce ether or ester; the strong chemical acting force is formed, which hinders free movement of PEG and demonstrates a solid-solid phase change behavior which is different from that when it moves freely, so the phase change temperature of SS-PCMs with various PEG mass fractions (about 60℃) is higher than pure PEG, and the phase change enthalpies (80.1~133.7 J/g) are 9.1%~17.4% lower than the theoretical phase change enthalpies. The intermediate connectors of PEG are ether groups that can move freely, and the amount of the terminal hydroxy groups is small, most segments of PEG can crystallize and display phase change behavior, and its crystallization property is stable. In addition, there is no thermal degradation in SS-PCMs below 382.6℃, thus it can be concluded that the composites have a high thermal stability. © 2016, Editorial Board of Polymer Materials Science & Engineering. All right reserved.