Abstract
The Tootal-Broadhurst-Lee Company's method was improved as follows: A cloth is conditioned for 2 days at 25°C and 65% R. H., from which the test pieces of 2cm long and 1cm wide are cut by means of a cutter. A test piece is folded across the narrow dimension and placed between two glass plates and loaded with a 500gm weight for 1hour. It is then allowed to recover for 10min. while hung over a horizontal wire of 0.3mm diameter, and then the distance l between the ends is read with a calipers. During the test the air is conditioned at 25±0.5°C and 65±1% R. H.
The long dimension of the test piece was shortened to 2cm, in order to obtain the value of l, l=2sinθ/2 where θ is the crease angle.
The process of crease recovery was followed in order to estimate the value l at equilibrium from an exact value after 5 or 10min. recovery period. It is found that l changes in the following relation for cloths. _??_ (1)
where l_??_ is the value of l at t=o, a1, a2 and a3 are the constants, t the time of recovery, and λ1, λ2 and λ3 are the relaxation times.
In the case of yarn two relaxation times λ1, λ2 are given for recovery, and one relaxation λ1 for filament. The values of λ1, λ2 and λ3 are 50_??_70, 10_??_20 and 1_??_2min. in the case of the viscose yarn used.
In the range of t=3_??_20min., 160 samples of the cloths, which were woven variously by using the same viscose yarn, containing partly the resin-treated, are all indicated by the equation (1).
