Effects of Temperature, Humidity and Strain Rate on Tensile Stress-Strain Curves of Spandex

Abstract

In order to investigate the effects of temperature, relative humidity and strain rates on the stress-strain curve of spandex yarn, tensile tests were performed under many kinds of conditions including impact tests.Stres-strain curves of spandex yarn were obtained on 7 levels in temperature ranging from 243 K to 333 K.Making an approximation with a linear equation, the relation between the modulus E obtained at the temperature ranging from 273 K to 333 K and the temperature was E=E20 (1 +KTΔT). Where E20. was the modulus at 293 K in temperature (=1.0 × 10-2N/tex), KT was the coefficient that gave the change in modulus with the change of 1 K in temperature (=-1.8 x 10-2 K-1) and ΔT was the discrepancy in temperature from 293 K. Under 273 K in temperature, the increase in the modulus with the decrease in temperature was much larger than the slope of the approximate line.In relative humidity ranging from 35 to 95% RH, 5 levels of tensile tests gave the following relation ; E=E65, (1+KHΔH), where E65. was the modulus at 65% RH (= 8.0 x 10-3N/tex), KH was the coefficient that gave the changein modulus with the change of 1% in relative humidity (=7.2 × 10-3) and ΔH was the discrepancy from 65% RH.Tensile tests on 7 levels in strain rates ranging from 1.67 × 10-3 to 147s-1 were performed. The relation of E=E1 (1 +Kv, log e) between the modulus and the strain rate was approximately expressed by a linear equation.Where E1 was the modulus at 1 s-1 in strain rate (=1.0 × 10-2 N/tex), Kv was the coefficient that gave the change in modulus with the change of one order in strain rate.