Functionalization of isotactic polypropylene with acrylic acid in the melt: Synthesis, characterization and evaluation of thermomechanical properties

Functionalization of isotactic polypropylene (iPP) with acrylic acid (AA) was studied in the melt mixing head of a brabender plasticorder (BPCR) and a twin screw extruder (TSE) using peroxide initiators. The effect of monomer and initiator concentrations on percent grafting, grafting efficiency, homopolymer formation and torque generation was studied in a BPCR. The percent grafting and homopolymer formation were found to increase with an increase in AA content, whereas grafting efficiency and torque values decreased. Functionalized PP was also produced continuously in a TSE by varying two different initiators, namely benzoyl peroxide and dicumyl peroxide. Graft copolymers were characterized by infrared (IR), wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The melt flow index, intrinsic viscosity and thermomechanical properties of functionalized polypropylenes were evaluated. An improvement in thermomechanical properties and beta-phase formation was observed. (C) 1996 Elsevier Science Ltd