The non-linear viscoelastic behaviour of human hair at moderate extensions.
We report the results of experiments carried out on the stress relaxation of slightly stretched human hair. The results show that human hair is viscoelastic, and that when quickly extended to a moderate degree (0.5-6.5%) and held, the force generated will fall to half its original value in about 15 h. However, the relaxation process is also dependent on extension, so that iso-chronous (constant time) data is non-Hookean. We show that the iso-chronous stress/strain behaviour departs from linearity at about 1% extension and the modulus progressively decreases thereafter according to a power-law relationship with strain.
Barnes
H A
HA
Unilever Research, Port Sunlight, Wirral CH63 3JW, U.K.
Roberts
G P
GP