Vinyl acetate content influence on thermal, non-isothermal crystallization, and optical characteristics of ethylene–vinyl acetate copolymers

Ethylene–vinyl acetate (EVA) copolymers with different vinyl acetate (VAc) contents can be used in a wide range of daily application areas. However, the relationship between VAc contents and the thermal behavior and optical properties of EVA are rarely reported. This work aims to investigate the effect of varied VAc contents on thermal behavior and optical properties of EVA copolymers, and further analyze the suitable application areas of different EVA copolymers. Crystallization behaviors present that three-dimensional spherulitic crystallites or two-dimensional crystallites of lamella type were formed presumably during the crystal growth from the primary crystallization process. Meanwhile, the lamellar thickness of EVA copolymers decreased from 3.05 nm to 1.34 nm with VAc content increases from 0 to 33% (by wt). Thermal behavior indicated that the thermal stability of EVA copolymers was weakened with the increase in VAc content. EVA copolymers involved two decomposition steps as deacetylation process of the VAc group and polyethylene chain scission. Nevertheless, the transmittance of EVA copolymers increased to 92% with rising the VAc content to 33% (by wt). The dynamic mechanical thermal analysis (DMTA) technique was adopted to study the glass transition temperature and viscoelastic behaviors of EVA copolymers. The thermal behavior, optical, and mechanical properties would ultimately influence the application areas. Thus, combining the thermal behavior, optical, and mechanical properties can provide a better perspective on the application areas of EVA copolymers with different VAc contents. Graphical abstract