(188i) On the Unuse of Compatibilizer in PVC/SAN Blends

PVC/SAN, polyvinyl chloride and Styrene Acrylonitrile copolymer and PVC/AMS-AN, polyvinyl chloride and alphamethyl styrene and acrcylonitrile copolymer blends have been studied for miscibility as a function of AN copolymer composition by Padwa et. al. (1). The phase behavior of these blends are discussed in this study. SAN containing 12-26 wt% AN is miscible with PVC and immiscible outside this compositional window. When the AN content of the matrix SAN in ABS engineering thermoplastic is 35 wt% the impact strength of the ABS/PVC Triax 2000 blends exhibited a large negative deviation from the additive value of blend constituents. This can be attributed to the immiscibility of the PVC/SAN35 blends. SAN with 35 wt % AN when replaced with SAN with 25 wt % AN the compatibility of the blend was found to increase. Thus compatible and miscible blends can be formed between PVC/SAN with SAN25. At 25% AN PVC and SAN are thermodynamically miscible as well as compatible. A twofold increase of impact strength and positive deviation from the simple additive values of blend constituents was confirmed by technologists. The stress whitening of all fractured surfaces after the impact test was observed. Partially miscible blends were formed for some compositions. The phase behavior including the binodal and spinodal are derived for PVC/SAN25 system. The criteria of equilibrium and stability were applied to the EOS and binary interaction values available in the literature were used. This story can serve as an good example of technology and academic modeling having a synergestic improvement in both the performance of product as well as better understanding of the science.