Friction, lubrication and wear of synthetic fibres

Abstract

This paper is divided into four parts. The first deals with the friction of synthetic fibres and polymeric materials in general. It is shown that the frictional behaviour depends both on the load and on the shape of the surfaces. For crossed fibres it is found that the coefficient of friction μ is proportional to W−β D2β, where W is the load, D the fibre diameter, and β a suitable constant, usually about 0.2. This behaviour is explained in terms of the adhesion theory of friction, the variation in friction with load and shape being attributed to the corresponding variation in the true area of contact. Good correlation over a load range of 109: 1 and over a range of surface curvatures of 320 to 1 is obtained.Part II of the paper describes the frictional wear of polymeric materials. A study of the surface damage produced supports the view that strong adhesion occurs at the regions of real contact, and that tearing and plucking of the surfaces takes place during sliding. An investigation of the frictional damage produced on fibres (using reflection electron microscopy) shows that the type of damage observed depends on the intensity of the frictional surface traction.In Part III some experiments on the boundary lubrication of polymers are described. In general, boundary lubricants are less effective on polymers than on metals and a number of reasons for this are discussed. Finally in Part IV a short account is given of some recent work on the friction of yarns over cylindrical guides. The results bring out a point that has not been considered previously in the friction of yarns in textile technology: — the importance of hydrodynamic factors and the role of the viscosity of the lubricant or finishing agent employed.