Thermoset polyester with phase changeable fillers for heat storage

Abstract

In this study, emulsions and sols of unsaturated polyester, containing phase changeable fillers (PCM) PEG-4000, paraffin, and Wood's metal, were prepared. Unsaturated polyester was the continuous phase and fillers were the discrete phase. These fillers were well distributed and dispersed in unsaturated polyester. Emulsions and sols containing different proportions of fillers were prepared, and the continuous phase was cured with initiator, methyl ethyl ketone peroxide (MEKP) and accelerator; cobalt naphtanate. After curing, the product becomes a thermoset polyester composite which was filled with homogenously distributed PCMs. Mechanical, thermal properties, and surface hardness of cured material were examined. DMTA (Dynamic Mechanical Thermal Analysis), DSC (Differential Scanning Calorimeter), SEM (Scanning Electron Microscope), and shormeter were used for these purposes. The mechanical properties of cured resins vary with PCM content. In paraffin and Wood's metal filled samples, the filler is a load bearing component. At phase change temperatures of the fillers, the samples show observable changes in dynamic mechanical properties. Maximum working temperatures of cured samples also decrease with increasing filler amount. Neat polyester does not show any melting transition, however, paraffin and Wood's metal filled samples show melting transitions. PEG-4000 filled samples do not show melting transition. Around the melting point of fillers materials absorbs a certain amount of heat. Except PEG-4000 filled samples, paraffin and metal filled samples show an endotherm around the melting point of filler while materials themself show no indication of melting externally and retain their physical shape.