Thermal Aging of Twaron Fibers

Abstract

The residual effects of thermal aging on Twaron fibers have been studied using X-ray diffraction, weight analysis, scanning electron microscopy and tensile testing. X-ray data from isothermally aged fibers indicate the introduction of changes at the level of the crystal lattice, which include reduction in crystallinity, variations in 20 values, half width and azimuthal spread of reflections. Isothermal aging also introduces weight loss. Examination of the surface of fibers has shown that damages in the form of holes, materials deposits, etc., are introduced by isothermal aging. These data on Twaron further show that the thermally induced effects are controlled by two parameters: temperature T and cumulative exposure time to T, i.e. tcum(T). Among the tensile properties, the tensile strength is found to be more sensitive to thermal aging than modulus. In addition to the structural studies on the thermal aging behavior of Twaron, a one-to-one comparison has also been attempted between the tensile behavior of Twaron and Kevlar 49 fibers, which are also made up of the same polymer.