MECHANICAL BEHAVIOR OF WOOL FIBERS

Abstract

Relaxation curves of wool fiber streched 10-25 per cent in aqueous media and phenol solution have been firstly determined. A conditioning temperature of 50°C was chosen, being as high as can be used without chemically damaging the wool fiber. Conditioning for half an hour at this temperature between measurements resulted in reproducible relaxation curves, as long as the period of extention of the fiber did not exceed 30 per cent.An apparatus used is constructed with the magnetostriction constructed for measuring the relaxation of stretched fiber. The output from the strain meter is applied to inkwriting oscillograph from the start for 10 seconds and after this time range value of valve voltmeter was measured.From the relaxation curves the reciprocal absolute temperatures corresponding to each test and the time required to attain the stress of 3.5×105g/cm2_??_4.75×105g/cm2 are obtained. The points for each specified stress are seen to lie in straight line. From the slope of these lines, the energies of activation for relaxation process in water are found from each deformation (15, 20 and 25 per cent) to be approximately 10Kcal, 20Kcal and 25_??_30 Kcal.The amount of breaking of hydrogen bonds depends on the concentration of phenol solution and temperature. With increasing temperature and concentration of phenol solution the rate of the stress relaxation becomes smaller than under the wet condition. Supplementary measurements of relaxation at various humidity were perfomed during 1/10sec_??_3000sec appling the former method. The each relaxation curve may be shifted log time scale and master relaxation curve may be constructed.