Effect of Stretch-ratio and Heat-treatment at Spinning on Thermo-elastic Properties of Acrylic Fiber in Water

Abstract

Relations between quasi-equilibrium stress and temperature under constant length in water have been determined in the range of strain up to 60% for wet-spun acrylic fibers prepared under different spinning condition, and in the range of strain up to 140% for cross-linked acrylic fiber. From analysis of these data, the changes of the entropy component and internal energy component of the fibers with strain were calculated.
Quasi-equilibrium stress-strain curves are separated into 2 parts, in which the first elastic region has modulus of 10MPa order, and the second elastic region has modulus of 1MPa order, close to that of natural rubber. In the first region, relatively small stress relaxation and large elastic recovery after stress relaxation are observed.
Relaxation of acrylic fibers in steam after stretch in process lowers contribution of energy component and raises glass transition temperature of the fiber. These changes of fiber structure reflect to the lower stress relaxation and the higher elastic recovery.