Characterization and Continuous Extrusion of Isotropic and Anisotropic Poly(p-Phenylene Terephthalamide)/Sulfuric Acid Solutions to Form Ribbons and Blown Film.

摘要

An experimental characterization and processing study of redissolved Kevlar and poly(p-phenylene terephthalamide)/sulfuric acid solutions is reported. Polarized light microscopy studies show the development of an anisotropic phase. When two phases coexist, negatively birefringent spherulites are observed. At higher concentrations, a single phase of coalescing spherulites is seen and following melting and subsequent cooling, nematic (threadlike) structures are observed. Viscosity and normal stresses were measured at various concentrations and temperatures. A yield stress is exhibited at room temperature. Both room temperature and 60 degree C viscosity versus concentration curves display maxima. The solutions in concentration ranges from 2 to 12% have been extruded as ribbons and as annular blown tubular film. Processing variables and problems are discussed. Wide angle x-ray scattering patterns of films show orientation. Tensile properties have been measured on films. (Author)