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Mechanical behavior of dual‐rubber‐modified SAN
Author(s) -
Fowler M. E.,
Keskkula H.,
Paul D. R.
Publication year - 1988
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1988.070350613
Subject(s) - crazing , materials science , composite material , natural rubber , toughness , brittleness , acrylonitrile , shear (geology) , copolymer , emulsion polymerization , emulsion , methyl methacrylate , deformation (meteorology) , molding (decorative) , polymer , chemical engineering , engineering
The use of either an SBS block copolymer or an emulsion‐made methyl‐methacrylate‐grafted rubber alone failed to give any significant increase in the toughness of brittle poly(styrene‐co‐acrylonitrile) (SAN), even at concentrations up to 50%. However, a combination of the two rubber modifiers produced a strong synergistic toughening. All specimens were prepared by injection molding; however, annealing to relax orientation did not significantly alter this synergistic effect. The use of mechanical dilatometry showed that post‐yield deformation of blends containing both modifiers involved some crazing just after yielding but subsequent deformation was mostly due to shear yielding. Addition of SBS alone to SAN resulted in a mixed crazing/shear yielding mode of post‐yield deformation with the relative proportions of the two mechanisms being constant up to failure. In contrast, the small emulsion graft particles alone gave rise to a predominant shear yielding deformation. A qualitative mechanism for the synergism is discussed.