The ultimate tensile properties have been determined for a wool yam before and after chemical modification as a function of temperature, strain rate, and regain. Under the conditions prevailing at failure, wool behaves viscoelastically, the breaking stress and breaking strain each varying with the test conditions. Applying the WLF equation allows data obtained at different temperatures to be superposed to give master curves showing breaking stress or strain as a function of reduced strain rate at a chosen reference temperature. Failure envelopes give the locus of failure in tensile deformation under a wide range of conditions. Possible reasons are presented for the fracture be havior of the different wools.
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