Studies on Thermal Degradation Behaviour of EVA/LDPE Blend

Abstract

Degradation of ethylene vinyl acetate copolymer (EVA; 28% VA content), low density polyethylene (LDPE) and their blends has been studied through thermogravimetric analysis (TGA/DTG). Pure EVA and its blends show a two stage decomposition, where the first stage is ascribed to the acetic acid elimination, i.e., the weight loss is proportional to the amount of acetate group present in the system. The second stage of decomposition is due to main chain scission when blends exhibit better thermal stability compared to pure polymers. The activation energy (E_a ) of second stage decomposition is calculated according to Freeman and Carroll's method. The maximum E_a is observed for pure EVA. The experimental E_a values of the blends are much greater than the theoretically calculated values based on the law of additivity. Among different blends maximum thermal stability is observed for the 50:50 EVA/LDPE system. Infrared spectrophotometry has been used to investigate about the possible reason behind the higher thermal stability of the blends compared to pure components. The effect of crosslinking and two different at mospheres, namely nitrogen and air, on thermal degradation have also been studied.