Preparation of polypropylene/poly(styrene- co -(butyl methacrylate)) nanoblends by diffusion and subsequent copolymerization of monomers in isotactic polypropylene pellets

The diffusion and subsequent copolymerization of styrene (St)/butyl methacrylate (BMA) mixed monomers in i PP pellets to prepare copolymer nanoblends were investigated. The diffusion step was carried out at 90 °C for 2 h in water, and the copolymerization was initiated by the addition of BPO with the aid of a small amount of St. The diametrical distributions of both St and BMA units and their ratio St/BMA were investigated by micro FTIR. Both St and BMA can diffuse into the centres of i PP pellets. The diametrical distribution of St/BMA ratio is constant in all the copolymer blends. The copolymer composition depends on the comonomer feed ratio. The molecular weights of the copolymers were measured by GPC after extraction with tetrahydrofuran. The phase morphology of the copolymer blends was investigated by FESEM, showing the average particle sizes of less than 100 nm. DSC measurements show that the diffusion and subsequent copolymerization of St/BMA monomers only occur in the amorphous regions of i PP pellets.