| abstract |
A normally amorphous condensation polymer is crystallized by foaming it with a chemical blowing agent at a temperature above the softening point of the polymer, extruding the molten polymer to form a solid foam and maintaining the foam at a temperature above the glass transition temperature until crystallization occurs. The crystallized polymer foam may be used as a structural foam. It can be used in solid state polymerization to obtain polymers of enhanced degree of polymerization. |