Physical Ageing and Annealing in Fibers and Textile Materials: Part V: Master Stress Relaxation Curves for Annealed Textile Materials

The theory of viscoelasticity of textile assemblies developed in Parts I and III of this series of papers is applied to an experimental study of the performance of fabrics after physical equilibration processes such as ageing and annealing. The fabrics studied include those produced from wool and polyester fibers and also wool/polyester blends. The effect of annealing variables (temperature, time, and regain) on the fabric visco-elastic performance has been analyzed using the free volume concept. The fabric stress relaxation curves for any given annealing conditions can be predicted from two time shift factors, one depending on annealing temperature and the other on annealing time, and the knowledge of the fabric stress relaxation spectrum. The time shift factors are used to construct a series of master stress relaxation curves, thus providing a convenient means of describing the ageing and annealing behavior of textile materials. The relationship between ageing and annealing performance has also been examined for wool fabrics. The results indicate that the ageing and annealing processes can both be considered in terms of similar mechanisms, and the annealing process may be regarded as an accelerated ageing phenomenon.