THE DEFORMATION-BEHAVIOR OF THIN-FILMS OF POLY(STYRENE ACRYLONITRILE) POLY(STYRENE MALEIC-ANHYDRIDE) BLENDS

The deformation behaviour of thin films of poly(styrene-acrylonitrile) (SAN) and poly(styrene-acrylonitrile)/poly(styrene-maleic anhydride) (SAN/SMA) blends was investigated at a range of different temperatures and strain rates. It is found that SAN shows a transition from shear yielding to disentanglement-induced crazing with rising temperature or decreasing strain rate. Addition of SMA leads, in the regime where SAN shows shear yielding, to more crazing and thus a more brittle behaviour. In the regime where SAN shows disentanglement crazing, addition of up to 50 wt% of SMA apparently leads to a rise in the monomeric friction coefficient in the blend, and therefore to a suppression of the disentanglement crazing mechanism. Still higher levels of SMA addition lead to pure crazing.