PHASE BEHAVIOR OF BROMINATED POLY(ISOBUTYLENE-co-4-METHYLSTYRENE)/ GENERAL PURPOSE RUBBER BLENDS

The themiodynarmc interaction and phase behavior of elastoineric blends, specifically brominated poly(isobutylenefo-4-metbylstyrene) and a general purpose rubber, polybutadiene, have been examined using small-angle neutron scattering (SANS) and cloud points measurements. The low molecular weight equivalent of each segment was used to produce a single phase blend from which the Flory-Huggins interaction parameter (chi) was extracted. The results were analyzed using the random copulymer formalism. The results show that the "repulsive" interaction between the isobutylene and 4-methylstyreiie monomer unite enhances the compatibility ofbrominaled poly(isohutylene-co-4-methylstyrene) with polybutadiene. A maximum in compatibility occurs at approximately 50 mol % 4-methylstyrene. This fundamental informatiun is essential for the determination of the phase behavior of these materials, and their regions of miscibility/immiscibility. In addition, this information can be used to calculate the optimum copolymer composition for this scientifically interesting and technologically impurlant blend system.