THE FORMATION OF BUTYL-RUBBER MODIFIED POLYSTYRENE

A method was investigated for preparing butyl-rubber modified polystyr ene. Styrene was polymerized free-radically in the presence of dissolv ed butyl rubber and the process was monitored by dark-field optical mi croscopy. A phase inversion occurred during the polymerization process leading to a system consisting of rubber particles dispersed in a pol ystyrene matrix. The particles had a multiple-inclusion structure simi lar to that found in some polybutadiene toughened polystyrenes.