Preparation of linear low density polyethylene/poly blend films with various transparencies

Linear low density polyethylene (LLDPE)/poly(ethylene-co-vinyl acetate) (EVAc) blend films having various vinyl acetate (VAc) contents (12, 18, and 25 wt.%) with various degrees of transparency were prepared using a hot plate press. Effects of VAc contents in EVAc and ratio of EVAc in LLDPE/EVAc blend films on the structure and properties of these films were investigated through a series of instrumental analyses. The transparencies of films were classified into three types: non-transparent (1-75 T(%)), semi-transparent (76-85 T(%)), and transparent (86-100 T(%)). With increasing the contents of VAc in EVAc and the ratio of EVAc in blend films, the transparencies of films were increased. The differential scanning calorimeter curves of blend films show that there are two obvious endothermic peaks at around 125 and 75-85°C, which corresponded to the melting of the LLDPE and EVAc crystals, respectively. The intensity of crystalline peaks of LLDPE decreased as the ratio of EVAc in blend films was increased. The thermal stability of blend film decreased with increasing degree of transparency. This might be due to the fact that transparent film can contain higher amount of amorphous regions, which were degraded at lower temperature than that of non-transparent films having high contents of crystalline regions. The storage modulus of non-transparent films was higher than that of semi-transparent films due to a higher crystallinity.