Preparation of acrylic core/shell polymer and its application in toughening rigid PVC matrix

Poly(n-butyl acrylate)/poly(methyl methacrylate) core/shell polymer (ACR) was prepared by semi-continuous emulsion polymerization. The instantaneous conversion is higher than 85% and overall conversion is over 95%. Comparison of theoretically calculated particle diameters with those measured experimentally show that the particles have grown without significant secondary nucleation occurring. The TEM analysis verified the morphology and the particle size. When it was used to modify PVC matrix, the PVC/ACR blend occurres brittle-ductile transition with the addition of 3 phr ACR. The Charpy impact strength reaches 16.51 kJ/m2, while the tensile keeps a relative high value (61.37 MPa). The SEM observation was used to explain the toughening mechanism. The ACR modifier is dispersed homogeneously in the PVC matrix, and the fractured surfaces show the networked structure and ductile deformation. The particle with approximately 180 nm of rubber-phase yields the effective impact absorption while minimizing the loss of tensile properties. This result will be used in the industrial scale in the nearest future.