SYNTHESIS OF ETHYLENE-PROPYLENE RUBBER GRAFT-COPOLYMERS BY BORANE APPROACH

This paper describes a new method to prepare graft copolymers which ha ve an EP rubber backbone and several free radical polymerized polymers grafted thereto. The process involves hydroboration of commercial EPD M rubbers, such as poly(ethylene-co-propylene-co-1,4-hexadiene hylene- co-propylene-co-5-ethylidene-2-norbornene), with 9-borabicyclononane ( 9-BBN). The resulting secondary alkyl-9-BBN moieties in the EPDM copol ymers were then exposed to oxygen in the presence of free radical poly merizable monomers. Under certain conditions, the selective autoxidati on reaction of secondary alkyl-9-BBN took place to create desirable po lymeric radicals which can in situ initiate free radical polymerizatio n. High graft efficiency was observed with controllable copolymer comp ositions. The graft copolymer of EP-g-PMMA is used to show the chemist ry as well as some of the physical properties.