Measurement of glass transition temperature of crosslinked EVA encapsulant by thermal analysis for photovoltaic application

摘要

The purpose of the experiment was to better understand the changes due to thermal transitions and the molecular organizations of EVA encapsulant material after cross linking process by thermal analysis methods as DSC, TSC and DMTA. DSC experiments on EVA show a glass transition at about -33.1 °C, which is characteristic of crystalline phase and an endothermic peak at temperature of 55 °C charac-teristic of amorphous phase. The basic results by TSC technique is that there are two relaxations that are reproducibly observed in crosslinked EVA encapsulant material. At temperature polarization 60 °C, a low temperature relaxation occurs at temperature -24.4 °C and a high temperature relaxation occurs at temperature +30.4 °C. DMTA results exhibit two tan5 peaks located at -14.9 °C and +66.6 °C. In addition, our results reveal that the glass transition temperature determined by TSC experiments in depolarization mode is more relevant than DSC and DMTA methods. TSC was chosen due to its low equivalent frequency consideration, useful to study encapsulant material exhibiting multiple relaxations.