Thesis Details

Thesis Title: The effect of relative humidity on stress-relaxation of nylon yarns at constant strain
Thesis Author: Arthur F. Cacella
Abstract: The elasto-viscous behavior of high polymeric materials is extremely complex. Various attempts have been made in the past 50 years to analyze mechanical behavior in terms of mechanical models composed oflinear elements (Hookean springs and Newtonia dashpots). More recently, a theory of non Newtonian flow has been developed by Tobolsky and Eyring which enables the characterization of non-linear visco-elastic behavior by means of creep or relaxation experiments. The present work demonstrates the application of stress-relaxation data to the Tobolsky-Eyring theory of mechanical properties of high polymeric materials for the purpose of obtaining information on the flow phenomena involved in stress relaxation of nylon yarn at various humidities. An apparatus employing a bonded metalectric strain gage was used for measuring the stress relaxation of nylon yarn at constant extension. The data obtained indicate that: 1. The number of flow units involved in stress relaxation of nylon increases as the initial load increases. 2. Rupture of a nylon fiber is caused by slippage of hydrogen bonds. 3. No significant change of stress relaxation with relative humidity can be deduced, not without further experimentation.