Toughened polypropylene with balanced rigidity (I): Preparation and chemical structure of toughening master batch

The title toughening master batch (TMB) was synthesized in a low-viscosity reaction system by using dynamic vulcanization technique starting front pol ypropylene (PP) as the matrix resin and ethylene-propylene or butadiene-sty rene elastomer as the toughening through a polymer-bridge conjunction deriv ed monomer containing a carbonate group in the presence of a free radical i nitiator. The chemical structure of the TMBs and the effects of technologic al conditions on structural parameters were investigated using fractional e xtraction and infrared spectroscopy. The prepared TMBs consisted of unreact ed PP, unreacted elastomers, graft copolymer of PP and/or Elastomers contai ning branched chains formed by bridging agent, and crosslinked copolymer of PP and/or elastomers in conjunction with polymer bridge chains derived fro m bridging agent. Results showed that the PP existed in graft and crosslink ed forms was in the range of 3-21 wt% and that of the elastomer toughening agent was in the range of 50-70 wt%, grafting and bridging efficiency of br idging agent was in the range of 62-88 wt%, graft copolymer content in the total TMB was in the range of 0.18-3.65 wt% and crosslinked copolymer conte nt was in the range of 22-42 wt%. Copyright (C) 2000 John Wiley & Sons, Ltd .