Casting films of polymers of meta-phenylene isophthalamide

摘要

Film of a wholly aromatic polyamide, at least 85% of the repeating units of which are meta-phenylene isophthalamide units, which is undrawn and noncrystalline and which has improved impact strength. Such film is made by heat-treating film of the polyamide which is undrawn and noncrystalline at 400 DEG to 300 DEG C. for from 2 seconds to 2 minutes while maintaining the film at constant length and width permitting it to shrink by at most 20% in each of the length and width.