Properties and structure of nylon fibers in relation to drawing and aqueous phenol treatments

The changes in nylon 66 fiber structure and properties which take place during drawing and aqueous phenol treatments were studied by means of measurements of length, birefringence, density, moisture regain, x‐ray diffraction, stress–strain behavior, and sound velocity. Drawing was found to establish molecular orientation along the fiber axis predominantly in the early stages, whereas the development of lateral order occured primarily after a certain level of orientation had been achieved. Treatments in aqueous phenol solutions caused longitudinal contractions which depended on phenol concentration (1‐5%), draw ratio (1‐6), and the tension on the fiber during the treatment. The treatments resulted in an increase in the lateral order, decrease in orientation and corresponding changes in mechanical properties. Moisture regain was inversely related with density for the untreated fibers of various draw ratios, but the relationship became complex after treatments in phenol. The data are interpreted in terms of changes in the lateral order distributions, which permits an increase in the fibers' sorptive capacity despite an increase in the mean lateral order.