STUDIES ON THERMAL-DEGRADATION BEHAVIOR OF EVA LDPE BLEND/

Degradation of ethylene vinyl acetate copolymer (EVA; 28% VA content), low density polyethylene (LDPE) and their blends has been studied thr ough thermogravimetric analysis (TGA/DTG). Pure EVA and its blends sho w 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 dec omposition is due to main chain scission when blends exhibit better th ermal 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 expe rimental E(a) values of the blends are much greater than the theoretic ally calculated values based on the law of additivity. Among different blends maximum thermal stability is observed for the 50:50 EVA/LDPE s ystem. Infrared spectrophotometry has been used to investigate about t he possible reason behind the higher thermal stability of the blends c ompared to pure components. The effect of crosslinking and two differe nt atmospheres, namely nitrogen and air, on thermal degradation have a lso been studied.