Method of producing high strength fibers

A method of making a high strength, high creep recovery polymeric fiber, comprising the steps of:

• (a) providing a fiber of a polymeric material selected from the group consisting of polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, polyamide, and polybutylene terephthalate;
• (b) crosslinking the polymeric material;
• (c) thereafter heating the fiber to a temperature T.sub.1, which (i) in the event the polymeric material is amorphous, is above the glass transition temperature T.sub.g of the polymeric material and (ii) in the event the polymeric material is crystalline, is above the second order transition temperature T.sub..alpha..sbsb.c and below the crystalline melting temperature T.sub.m of the polymeric material;
• (d) drawing the heated fiber to a draw ratio of at least about two at a rate of at least about 200% per minute;
• and
• (e) cooling the drawn fiber;
• whereby a fiber is obtained which has a tensile strength of at least about 70,000 psi and which, when subjected to a stress of 15,000 psi at 25.degree. C. for at least 1 hour, thereby causing the fiber to deform, is capable of substantially complete recovery to its undeformed configuration when the stress is removed.