Characterization and Continuous Extrusion of Isotropic and Anisotropic Poly(p-Phenylene Terephthalamide)/Sulfuric Acid Solutions to Form Ribbons and Blown Film.
Technical rept. 1 Apr 77-25 Sep 78,
TENNESSEE UNIV KNOXVILLE
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An experimental characterization and processing study of redissolved Kevlar and polyp-phenylene terephthalamidesulfuric 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
- Physical Chemistry