FUNCTIONALIZATION OF ISOTACTIC POLYPROPYLENE WITH ACRYLIC-ACID IN THEMELT - SYNTHESIS, CHARACTERIZATION AND EVALUATION OF THERMOMECHANICALPROPERTIES

Functionalization of isotactic polypropylene (iPP) with acrylic acid ( AA) was studied in the melt mixing head of a brabender plasticorder (B PCR) and a twin screw extruder (TSE) using peroxide initiators. The ef fect of monomer and initiator concentrations on percent grafting, graf ting efficiency, homopolymer formation and torque generation was studi ed in a BPCR. The percent grafting and homopolymer formation were foun d to increase with an increase in AA content, whereas grafting efficie ncy and torque values decreased. Functionalized PP was also produced c ontinuously in a TSE by varying two different initiators, namely benzo yl peroxide and dicumyl peroxide. Graft copolymers were characterized by infrared (IR), wide angle X-ray scattering (WAXS), differential sca nning calorimetry (DSC) and thermogravimetric analysis (TGA). The melt flow index, intrinsic viscosity and thermomechanical properties of fu nctionalized polypropylenes were evaluated. An improvement in thermome chanical properties and beta-phase formation was observed. (C) 1996 El sevier Science Ltd