Novel Foams From Styrene-Acrylonitrile Copolymers

Abstract

Styrene copolymer foams were prepared from expandable beads of various acrylo nitrile contents and the resistance of these foams to gasolines was evaluated. Minimum acrylonitrile content for resistance to pre mium gasoline was about 28.5%, whereas foams containing 18.5% acrylonitrile resisted regular grade gasolines. Conventional meth ods of preparing the high acrylonitrile-con taining foams gave unsatisfactory products, but an effective process was developed from studies of the kinetics of suspension copoly merization. Differential thermal and thermogravi metric analyses served to compare expand able 29%-acrylonitrile copolymer with ex pandable polystyrene. Although these poly mers are dissimilar in many characteristics, their copolymer foams exhibit no significant differences in physical properties.