Development of low temperature polycondensation processes and aromatic polyamides

There are two principal types of low temperature polycondensation processes: the two-phase process known as interfacial polycondensation and a single liquid phase process or solution polycondensation. Both procedures are widely used experimentally and have led to the preparation and evaluation of thousands of polymers. Types of polymers which are made commercially are polycarbonates, block elastomers, polyimides, and aromatic polyamides. Aromatic polyamides are produced commercially for two major end uses: (1) flame and heat resistant polymers in the form of fibers, films, molding powders, and papers, and (2) polymers with extended chains for high strength, high modulus fibers. The latter class of polymers give liquid crystalline solutions which make possible the direct formation of highly oriented, high strength fibers. Aramid fibers of this type are useful in cut resistant clothing, ballistics protection, asbestos replacement, ropes and cables, and reinforcement of resins and rubber. Continuing research on the low temperature procedures is leading to new variations and applications of these processes.