Morphological Changes in Nylon 6 and Effect on Mechanical Properties IV. Stress-Strain Cycles

Abstract

In the present series of papers we have investigated the effects of morphological changes (produced by treating the film with different swelling agents and also by heat treatments) on the mechanical properties of nylon 6 film. Parts I, II and III (1,2,3) have discussed the types of morphological change produced, dynamic mechanical properties, and stress-strain properties, respectively. In the present paper we have examined in more detail the effects produced on the stress-strain behavior, by use of stress-strain cycling. In particular, we have examined the nature of the recoverable and total work of extension at different points of the stress-strain curve (both before and after the yield point ) and at different temperatures (both below and above what is generally regarded as the glass transition temperature of the polymer).