Abstract

The work reported in this paper deals with the frictional properties of leather fibres, and supplements the extensive study of the mechanical properties of raw and tanned collagen fibres carried out by Morgan. Since the extensibility of leather is greater than that of the individual fibres the fibre weave must be disturbed when leather is distorted, and consequently inter-fibre friction must be of importance.

The choice, design and calibration of an apparatus for measuring friction is described, and details of the preparation and extraction of the fibres from leather together with the method of measurement are given. In the first experiment the effect of variations of temperature and humidity, load, stretching, etc., were studied to decide on suitable conditions for measurement of friction. In the second, factors were investigated which are known to be important in determining leather properties, i.e. the type of leather, the temperature and humidity at the time of test, lubrication, and the material on which friction was measured.

The results from the two experiments show that fibre friction is significantly influenced not only by changes in ambient conditions, but also by the character and type of leather. The most important observations are that vegetable tanned fibres have much lower coefficients of friction than do chrome tanned fibres (which accounts for the better mouldability of vegetable tanned leathers), and that increase in temperature of only 20 markedly reduces friction. These factors are of considerably greater im portance than either changes in humidity or degree of lubrication, the effects of which were surprisingly small.

The work reported here provides valuable information regarding the behaviour of leather under tension and on heat setting, and has shown that movement of fibre on fibre is undoubtedly an important factor in determining properties of leather.