36—the Ageing of Wool. Part Ii: The Ageing of Disorganized Fibres

Experiments are described in which the stress-relaxation and recovery behaviour in bending is determined during ageing for wool fibres previously disorganized by a treatment in boiling water and is shown to be generalized linearly viscoelastic. This behaviour is also shown to parallel that of the stress-relaxation and ageing behaviour of native fibres in torsion, which is known to reflect the behaviour of the matrix component of structure. The results are shown to be consistent with a hypothesis proposed by Rigby et al. It is also demonstrated that the microfibrillar regions of the fibre contribute a constant spring-like component to the modulus, which does not stress-relax or age but is destroyed when fibres are disorganized by a treatment in boiling water. It seems certain that the major mechanical effects observed during ageing result directly from processes occurring in the matrix.