Physical Ageing and Annealing in Fibers and Textile Materials

Abstract

The viscoelastic behavior of annealed fabric specimens produced from wool and manmade fibers has been assessed by measuring the fabric bending stress relaxation characteristics. The study reveals that the presence of water provides an effective medium for de-ageing of fabrics produced from both wool and manmade fibers. Optimum annealing conditions occur when these fabrics are heated below the glass transition temperature of each fiber type at the equilibrium moisture regain corresponding to 20°C, 65% RH (the time taken depending on the annealing temperature). Under these conditions, the fabric bending stress relaxation rate is reduced to its minimum value, thus resulting in maximum fabric recovery from bending or wrinkling. The application of horizontal and vertical shift factors produces a master stress relaxation curve of aged and annealed fabric specimens produced from both wool and manmade fibers.

Electric-Field-Induced Actuation of Poly(vinyl alcohol) Microfibers

“…The parameters used to evaluate the bending properties of the PVA fibers were bending rigidity ( B ), which was measured from the mean slope in the range K = 0.5–1.5 cm –1 ( K is curvature), and the hysteresis of bending moment (2 HB ), which was measured at K = 1.0 cm –1 . The values were obtained using the following formulas: , where M is the bending moment, B f and B b are bending rigidities, and HB f and HB b are hysteresis of bending moments for face and back bending.…”