Relationship Between the Inverse Stress Relaxation and the Viscoelastic Recovery of Filament Yarns

Abstract

The relationship between two mechanical time-effects, inverse stress relaxation (IR) and viscoelastic recovery (VR, CR) in filament yarns is studied by modelling and experimentally in order to reveal possibilities to predict the amount of inverse stress relaxation by the viscoelastic recovery tests. The effects are studied on 16.6 tex acetate and 15.6 tex polyester multifilament yarns in two different testing cycles: the relaxation (R-) cycle and the creep (C-) cycle. It is shown that the statistical dependency of the amount of stress increase )(aFF− in the inverse relaxation test on the amount of strain decrease )(εε−a in the viscoelastic recovery test is suitably well defined by the power equation that can be useful to predict stress development in IR process by the data obtained in viscoelastic (creep) recovery test.