Method for foaming high temperature polymers using poly(alkylene carbonates) as foaming agents

Abstract

A process for producing cellular foamed articles from high temperature engineering polymers wherein polymeric blowing agents are utilized to expand the polymers. The process comprises mixing a first polymer capable of being foamed with a second polymer comprising at least one poly(alkylene carbonate) to provide a polymer blend; heating the polymer blend to a temperature sufficient to melt the polymer to be foamed and to decompose the second polymer to form gas inclusions within the first polymer; expanding the melted first polymer containing the gas inclusions to form a foamed article; and cooling the foamed article to a temperature below the melting or softening point of the foamed article. Polymers which may be foamed according to the process include those polymers which can tolerate processing temperatures in excess of 260.degree. C. Suitable poly(alkylene carbonate) foaming agents include poly(propylene carbonate), blends of two or more poly(alkylene carbonates) and copolymers and terpolymers formed by polymerizing two or more oxirane compounds in the presence of carbon dioxide.

Dependencies are inferred from the claim text.