Modification of polypropylene via the free‐radical grafting ternary monomer in water suspension systems

Maleic anhydride, styrene, and butyl acrylate were grafted onto polypropylene (PP) via free-radical polymerization. The grafted product, polypropylene-g-(maleic anhydride–styrene–butyl acrylate) (PP-g-PMSB), was prepared in a water suspension system, and a nongrafted polymer, poly(maleic anhydride–styrene–butyl acrylate) (PMSB′), was produced at the same time. The optimal synthesis conditions were determined by orthogonal experiments. The crystallinity, thermal stability, melt flow rate, and hydrophilicity of the grafting samples were investigated in the presence or absence of PMSB′. The results indicate that the grafting percentage (Gp) of PP-g-PMSB and the content of PMSB′ (Cm) increased as the monomer content increased under the optimum reaction conditions. All of these ternary monomers were grafted onto the PP backbone as long-chain branches. With increasing Gp, PP-g-PMSB's polarity and thermal stability increased, the crystallinity decreased, and the molecular distribution became narrower. The contact angle decreased to 72.12° when Gp was 6.87%. With increasing Cm, the crystallinity and thermal stability of the grafting products decreased compared to PP-g-PMSB and the molecular distribution grew wider. The contact angle decreased to 63.51° when Cm was 3.64%; this indicated that the presence of PMSB′ further improved the hydrophilicity of the grafted products. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012