BUTYL RUBBER GRAFT-COPOLYMERS - SYNTHESIS AND CHARACTERIZATION

This paper discusses four closely related themes. (a) First, we presen t the synthesis of new butyl rubber graft copolymers that have a polyi sobutylene backbone and several free-radical polymerized polymers, suc h as poly(methyl methacrylate), in the side chains. The chemistry invo lves commercial butyl rubber, poly(isobutylene-co-isoprene) and free-r adical graft-from reaction using a borane reagent. (b) The selective a utoxidation reaction of secondary alkyl-9-borabicyclononane offers the conditions for producing desirable polymeric radicals in graft-from p olymerization with high grafting efficiency and controllable copolymer compositions. (c) The structure of graft copolymers is characterized. Several techniques, especially gel permeation chromatography measurem ent with on-line refractive index, photodiode-array and light scatteri ng detectors, were used to provide detailed microstructural informatio n. (d) Finally, compatibility is studied using graft copolymers as the compatibilizers in polyisobutylene blends.