Foaming conditions of high density polyethylene-natural rubber blends

Foams made from high density polyethylene (HDPE) and natural rubber (NR) bl ends, using azodicarbonamide as a chemical blowing agent, have been investi gated to establish a relationship between the structure and physical proper ties. The blends of HDPE, NR, epolene wax, chemical blowing agent, and nece ssary ingredients were prepared on a two roll mill. Subsequently, foamed st ructures of the blends were obtained by a single stage compression moulding . Results indicate that foaming process variables, i.e. heating time, blowi ng agent loading, ratio of HDPE/NR, crosslinking agent loading, and ratio o f HDPE/NR at a fixed crosslinking agent loading, affect the physical proper ties of the foams. Attempts were made to relate such properties as foam den sity, hardness, tensile strength, elongation at break, tear strength, flexu ral strength, elastic modulus, and gel content to the foam structure. The f oam structure was investigated using optical microscopy, in terms of the av erage cell size and its distribution. PRC/1603.