Solid‐state polymerization vis‐à‐vis fiber formation of step‐growth polymers. I. Results from a study of nylon 66

This study is directed toward synergistic integration of processing of nylon 66 fibers with solid‐state polymerization. The following two goals are sought through the incorporation of solid‐state polymerization after the initial shaping operation: eliminating some of the processing problems in the production of high molecular weight, high performance industrial fibers and attainment of improved mechanical properties via high molecular weight. Successful solid‐state polymerization has been achieved with as‐spun fibers of nylon 66 and molecular weights up to 280,000 g/mol have been obtained from a starting molecular weight of 40,000 g/mol. It is shown that much of the ductility of the starting fiber can be retained, or even enhanced, with solid‐state polymerization. Simulated drawing experiments using a thermal deformation analysis technique show an increase in the drawing potential of the solid‐state polymerized fiber as compared to the starting material. This has important implications regarding the ultimate properties that can be achieved in fibers of condensation polymers.