The Crosslinking Behavior And Encapsulant Properties Of EVA Film For Photovoltaic Modules Encapsulation

Ethylene vinyl acetate(EVA) was modified by various additives, including curing agents, coupling agents, antioxidants, UV stabilizers and so on, to prepare EVA film for photovoltaic modules encapsulation after molding.The crosslinking behavior of EVA was studied. The Avrami equation was applied to describe the isothermal crosslinking behavior and the Ozawa, Avrami-Ozawa as well as FWO equations were applied to describe the non-isothermal crosslinking behavior with the DSC data. These models fitted the experimental data very well, and the crosslinking reaction activation energy was calculated between110kJ mol-1and170kJ mol-1.The important short-term properties, crosslinking degree and adhesive strength were studied. The curing agents and lamination conditions had important influence on the EVA crosslinking degree. In a certain range, the increase of these factors resulted in the increase of EVA crosslinking degree, and the increase of crosslinking degree and the use of coupling agents were helpful to the EVA adhesive strength with the glass and TPT, and it reached the peak when the crosslinking degree was about85%and the content of coupling agents was about0.4%.The anti-aging property was studied by the speed-up climate aging experiments. The increase of crosslinking degree would enhance the anti-aging property and the transmittance of EVA. The usage of different kinds of antioxidants enhanced the EVA damp anti-aging property and the usage of UV absorber and stabilizer enhanced the EVA UV anti-aging property. The optimized EVA films performed well with light transmittance of92.7%and yellowing index under1.0. During the experiments, the UV aging was more destructive than the damp aging.