Property of ethylene vinyl acetate copolymer in melting processing

The study is focused on the processing behavior of poly(ethylene‐co vinyl acetate) (EVA) in high temperature, such as 200°C. The specimens are characterized using HAAKE minilab, dynamic mechanical analysis (DMA), and positron annihilation lifetime spectroscopy (PALS) to understand the rheological behavior and microstructure of EVA. It was concluded that in high processing temperature, the viscosity declined first and then increased. The PALS results showed that the free volume of EVA became large at the beginning, and became small afterwards. The glass transition temperature measured with DMA got lower at first and then nearly unchanged with increasing handling time. The results can be explained that the degradation of EVA prevailed, and then degradation was not dominant. A good correlation has been found between the processing time and temperature of the transition point in the viscosity curve.