Blends of photovoltaic-grade ethylene-vinylacetate copolymers and low-density ethylene-octene copolymers, their morphology and their thermal, mechanical, and rheological properties

Blends of photovoltaic-grade ethylene-vinyl acetate copolymer (EVA), defined by high VA-content and low crystallinity, and low-density ethylene-octene copolymer (EO) have been investigated with regard to their processing, thermal and mechanical properties as well as their morphology. It was found that the amount of EO in the blend has a strong influence on the shear thinning behavior, melt viscosity and therefore the required extrusion temperature and resulting ability to incorporate temperature-sensitive additives like a peroxidic crosslinking agent. A phase separated morphology was found for all blend compositions, though partial miscibility leading to co-crystallization was observed for EVA rich blends. EO rich blends show lower glass transition and higher melting point compared to neat EVA and exhibit higher elastic modulus at elevated temperatures as well as greater elongation at break during tensile testing while the light transmission is diminished. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47714.