Dynamic Mechanical Properties of Mechanically Deformed Filaments

Abstract

The effect of mechanical deformation on filament structure has been evaluated using a viscoelastometer. As a result of cyclic twisting, or torsional deformation, the fiber structure tends to disorient and behave more like an amorphous system where the loss factor (tan δ) increases as deformation cycles increase. Tensile cyclic loading, on the other hand, improves the orientation function as determined by sonic data, which include contributions from both the amorphous and the crystalline fractions as well as lateral order, as revealed by x-ray fiber diagrams. These structural changes give rise to lower values of tan δ. The decreased height and increased width of the loss peak at the a transition temperature substantiate the assumption that cyclic tensile loading improves orientation and lateral order through relaxation and strain condi tioning.