Effect of Acrylic Core-Shell Rubber Particles on the Particulate Flow and Toughening of PVC

Different types of acrylic core-shell rubber particles with a poly(butyl acrylate) (PBA) core and a grafted poly(methyl methacrylate) (PMMA) shell were synthesized. The average size of acrylic core-shell latex particles ranged from 100 to 170 nm in diameter, having the core gel content in the range of 35-80%,. The melt blending behavior of the poly(vinyl chloride) (PVC) and the acrylic core-shell rubber materials having different average particle sizes and gel contents was investigated in a hatch mixing process. Although the torque curves showed that the particulate flow of the PVC in the blends was dominant, some differences were observed when the size and gel content of the particles varied. This behavior can be attributed to differences in the plasticizing effect and dispersion state of various types of core-shell rubber particles, which can vary the gelatin process of the PVC in the mixing tool. On the other hand, the highest toughening efficiency was obtained using core-shell rubber particles with the smallest particle size (i.e., 100 nm). The results showed that increasing the gel content of the core-shell impact modifiers with the same particle size improved the particle dispersion state in the PVC matrix. The toughening efficiency decreased for the blends containing 100 and 170 nm rubber particles as the gel content increased. Nevertheless, unexpected behavior was observed for the blends containing 140 nm rubber particles. It was found that a high level of toughness could be achieved if the acrylic core-shell rubber particles as small as 100 nm had a lower gel content. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 2590-2597, 2009