Characterization and physical properties of new isobutylene-based graft copolymers

A number of isobutylene-based graft copolymers with different compositions are compared to several commercial thermoplastic block copolymers, such as SIS, SBS and SEES, in terms of morphology and viscoelasticity. The backbone of these graft copolymers is a terpolymer (BIMS) of isobutylene, p-methyls tyrene and p-bromomethylstyrene, and the side chains are either polystyrene or poly(2,6-dimethyl-1,4-phenylene ether). Graft copolymer synthesis, stat istics of graft formation, and stress-strain properties are described. Over all, these graft copolymers exhibit unique shear dependent viscosity effect s, such as rapid thickening (quick setting) at low shear and lower viscosit y (better processability) at high shear, compared to linear triblock copoly mers. The rheological behavior of these graft copolymers could be a key adv antage for high-shear calendering, extrusion, hot-melt spraying, and inject ion molding.