DYNAMIC STRUCTURE AND AQUEOUS ACCESSIBILITY OF POLY(P-PHENYLENE TEREPHTHALAMIDE) CRYSTALLITES

A more complete description of the morphology of poly(p-phenylene tere phthalamide) (PPTA) in both as-polymerized polymer and various fibre f orms is developed by the utilization of a number of methods (dark-fiel d transmission electron microscopy, X-ray diffraction, solid state n.m .r. spectroscopy, and partial isotopic exchange of accessible amide mo ieties). This description focuses primarily on the effect of lateral c rystallite dimensions on the microscopic dynamic structure and the con comitant macroscopic accessibility properties. The observation of a he terogeneous dynamic structure reflects the imperfect structural consol idation during the processing of PPTA in both as-polymerized polymer a nd fibre forms. The imperfect microcrystalline structure formed during processing is shown to be the origin of macroscopic accessibility for small molecules and also provides a plausible structural basis for bi ological accessibility.