Study on adhesion strength, thermal creep resistance, and light transmittance of ethylene‐polypropylene copolymer grafted with silane for photovoltaic application

Abstract

We investigated the possibility of using PP as an encapsulant in a photovoltaic module. PP is inexpensive but shows low adhesion strength to glass (and silicon wafer) due to its nonpolar nature as well as opacity due to its crystalline nature. We resolved these problems by employing metallocene catalyzed ethylene-propylene copolymer (EPR) and a nucleating agent to increase the transparency. Five EPRs having various propylene/ethylene ratios were investigated. EPRs having higher propylene content showed higher adhesion strength to the glass substrate. However, it is not appropriate to use EPRs with higher propylene content because they show low processability in calendaring processing. We therefore used a blend of two EPRs. The blend of the two EPRs showed somewhat low transparency. When the nucleating agent was incorporated in the blend, the transparency was remarkably increased. The adhesion strength to the glass plate was enhanced by a silane coupling agent.