STUDIES ON POLYCHLOROPRENE RUBBER - POLYSTYRENE INTERPENETRATING POLYMER NETWORKS (IPNS)

Network polyblends of polychloroprene rubber (CR) and polystyrene (PS) were prepared sequentially. The elastomer network was initially formed and allowed to swell in styrene monomer under specified conditions and subsequently the monomer was polymerized in situ to produce the elastomer/plastomer blends as interpenetrating polymer networks (IPNs). For formation of full-IPNs the styrene monomer contained small amounts of divinyl benzene (DVB), and for formation of semi-IPNs no DVB was used so that linear PS molecules were embedded in the elastomer network. Crosslink densities of CR and PS networks were varied by varying the doses of the vulcanization accelerator (viz. ethylene thiourea ETU, 0.1-1.0 phr) for CR and of DVB (0-5 wt/. of styrene) for crosslinking PS. Benzoyl peroxide was used as the initiator for the polymerization of the monomer or monomer mixtures. Physical, mechanical and morphological behaviour of the blends were studied and analysed with special reference to the effects of variation of ETU, DVB and the CR:PS blend ratio.