Styrene-acrylonitrile -grafted EPDM rubber

Styrene-acrylonitrile copolymer (SAN) and its impact modified versions, viz., ABS (polybutadiene rubber grafted SAN), ASA (acrylate rubber grafted SAN), AES (EPDM rubber grafted SAN)... 

Whilst the ASA materials are of European origin, the AES polymers have been developed in Japan and the US. The rubber used is an ethylene-propylene terpolymer rubber of the EPDM type (see Chapter 11) which has a small amount of a diene monomer in the polymerisation recipe. The residual double bonds that exist in the polymer are important in enabling grafting with styrene and acrylonitrile. The blends are claimed to exhibit very good weathering resistance but to be otherwise similar to ABS. 

A product made by grafting a mixture of styrene and vinyltrimethoxysilane on to EPDM (ethylene-propy-lene-diene monomer terpolymer rubber) was able to replace ABS (acrylonitrile-1,3-butadiene-styrene terpolymer).26 The product showed improved heat and light stability by the removal of the unsaturation. The need to use the carcinogenic acrylonitrile was eliminated. 

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