Theoretical Mechanism for Crimp

Abstract

A mechanism for crimp in wool fibres is proposed in which the inner root sheath of the wool follicle and the fibre cuticle rotate around the fibre cortex in the region just above the follicle bulb. The rotational movement of the fibre cuticle is passed on to groups of microfibrils in the cortical cells of the fibre through a gearing action, which causes them to be twisted into helices or spirals with the result that the cortical cells tend to shorten. The fibre deforms while still in the follicle causing the position of the fibre cortex near the bulb to change. This changes the magnitude and direction of the rotational movement of the inner root sheath and cuticle. A mathematical model of the mechanism is developed and several crimp forms, produced by using the model, are compared to those commonly observed.