Effect of Change in Temperature on the Torsional Energy Losses in some Polyamides

Abstract

THE mechanical energy losses in polyamide fibres have been determined from the damping of low-frequency free torsional vibrations (frequency approximately 0.3 c./sec.) between 20° and 130° C. A graph of energy loss against temperature shows a large absorption peak at 78° C. for undrawn dry 6.6 nylon filament. As the degree of orientation of the 6.6 nylon filament is increased by drawing, the absorption peak shifts to a higher temperature and the energy losses have a higher value. Fig. 1 shows the curves obtained for filaments of different degrees of orientation (draw ratio 1 (undrawn), 2, 3 and 4). The curve of the absorption peak is approximately symmetrical for undrawn 6.6 nylon; it changes in shape when the fibre is drawn. In a recent paper, Thompson and Woods1 reported similar results for polyethylene terephthalate for different degrees of orientation.