Improved ethylene-propylene rubber/silica interface via in-situ polymerization

Abstract

This article demonstrates an effective in-situ method for the preparation of ethylene-propylene rubber/silica composites (EPR/SiO2) via continuous process with two stages: in the first stage, functional olefin monomers containing trichlorosilane group (CSO) are designed and the terpolymerization of ethylene/propylene/CSO catalyzed by metallocene catalyst is implemented; in the second stage, by dispersing the SiO2 directly into the unterminated polymerization solution, the copolymer chains are anchored to the SiO2 particles via the reaction between the hydroxyl on SiO2 surface and pendant chlorosilane groups on the EPR chains. The CSO content in the copolymers was tailored in relatively wide range from 0.71 mol% to 4.68 mol%, which provided various chlorosilane groups for the anchoring reaction on SiO2 surface. Thus a series of EPR/SiO2chemical composites (with the SiO2 content of 13 wt% ∼ 85 wt%) were prepared via the highly efficient elimination reaction between Si-Cl and Si-OH groups. The dispersing morphology and stability of SiO2 in EPR/SiO2 composites were compared with that of the physically blended EPR/SiO2 systems. Owing to the covalent bonding between polymer chains and SiO2 particles, the problem of compatibility between the rubber and the filler was fundamentally solved.