Hydrosilylation of Impact Polypropylene Co-polymer in a

ABSTRACT: The production of hydrosilylated impact polypropylene (PP) copolymer has been demonstrated in a co-rotating twin-screw extruder. This has been accomplished through a two-step reactive extrusion process that involves: (i) the formation of terminal double bonds on a commodity PP copolymer through peroxide initiated degradation reactions, and (ii) the melt-phase functionalization of these double bonds with hydride-terminated polydimethyl-siloxane (PDMS). Spectroscopic analysis of the peroxide degraded PP and the purified hydrosilylated PP has been performed to confirm the attachment of PDMS onto the PP chains. In addition, the hydrosilylated PP has been characterized in terms of molecular, rheological, surface, and mechanical properties. It has been found that the two-step hydrosilylation reaction decreases molecular weight, imparts formation of branching/chain extension, decreases impact strength, and improves surface hydrophobicity. Finally, oscillatory shear measurements exhibit an unusual up-turn in the viscosity curve at low frequencies. KEY WORDS: reactive extrusion, impact polypropylene copolymer, hydro-silylation reaction, molecular weight, contact angle, viscosity up-turn