Modification of polypropylene through intercrosslinking graft copolymerization of poly(vinyl alcohol): Synthesis and characterization

Abstract

AbstractModification of polypropylene (PP) has been successfully carried out through intercrosslinking of poly(vinyl alcohol) (PVA), by chemical graft copolymerization method using benzoyl peroxide (BPO) as radical initiator. Prior to grafting, PP was irradiated by gamma rays at a constant dose rate of 3.40 kGy/h to introduce hydroperoxide groups. Optimum conditions pertaining to maximum percentage of grafting were evaluated as a function of different reaction parameters. Maximum percentage ofgrafting of PVA (75%) was obtained at [BPO] = 5.51 × 10−2 mol/L in 120 min at 70°C using 15 mL of water. Characterization of pristine PP and PP‐g‐PVA was carried out by FTIR, thermogravimetric analysis, and scanning electron micrography. Swelling studies were carried out in pure, binary, ternary, and quaternary solvent systems comprising of water, ethanol (EtOH), dimethylsulfoxide (DMSO) and N, N‐dimethylformamide (DMF) in different ratios. Maximum swelling values of PP‐g‐PVA (both composite and true graft) was observed in pure DMSO followed by DMF, EtOH, and water and it was also higher than that observed in mixed solvent system. Water retention studies of pristine PP and PP‐g‐PVA (both composite and true graft) were investigated at different time periods, temperature, and pH. Maximum % water retention of PP‐g‐PVA (composite) (108%) was observed in 8 h at 50°C in neutral medium (pH = 7). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008