BENDING RELAXATION PROPERTIES OF HUMAN HAIR AND PERMANENT WAVING PERFORMANCE - COMMENT

Wortmann and Kure (1) have developed a model to explain the greater ease of setting of a human hair fibre in a bent configuration as against a low extension. Their proposal for a distribution of Young's moduli from the surface to the core of the fibre, based on diffusion-controlled chemical breakdown during the reduction procedure, does not appear to be applicable to smaller diameter alpha-keratin fibres such as wools and cashmere goat hairs. Their model takes no account of the two-phase composite nature (4) of the cortex of alpha-keratin fibres. A simple model for setting of a fibre in a bent configuration based on the two-phase concept (2) leads to a universal explanation for the greater ease of set in bending as against set at low extensions.