Process for improving resistance of thermoplastic materials to environmental stress-induced crazing, and product produced thereby

摘要

The environmental stress resistance of an article made of an organic thermoplastic polymer is improved by subjecting a portion of the article to a tensile stress sufficient to strain the polymer beyond its yield point by cold working thereby effecting permanent elongation of the portion without subjecting adjacent areas to such a stress and releasing the tensile stress whereby the portion is elongated and thereby permanently subjected to compressive stress by the remaining material of the article. The article may be a refrigerator door liner which is illustrated and may be composed of polystyrene or a copolymer of styrene and acrylonitrile and optionally butadiene, or cellulose acetate butyrate.