Morphology and physical properties of closed cell microcellular ethylene-octene copolymer: Effect of precipitated silica filler and blowing agent

The morphology of the microcellular ethylene-octene copolymer (Engage) of both unfilled and precipitated silica-filled compounds was studied from SEM photomicrographs with variation of blowing agent and silica filler loading. The average cell size, maximum cell size, and cell density varies with variation of blowing agent and filler loading. Physical properties similar to relative density, hardness, tensile strength, elongation at break, modulus, and tear strength decreases with blowing agent concentration. The elastic nature of closed cells reduces the hysteresis loss compared to solid compounds. Set properties improve with blowing agent concentration. It is observed that stress relaxation behavior is independent of blowing agent loading (i.e., density of closed cell microcellular vulcanizates). Theoretically, flaw sizes are found to be about 3.08 times larger than maximum cell sizes observed from SEM photomicrographs. (C) 2002 John Wiley & Sons, Inc.