Frictional and elastic properties of high polymeric materials

The relationship of the elastic properties of solids to their frictional properties is discussed. By applying Hertz's equation for deformation of solids in contact, it is shown that while the asperities on metallic surfaces are deformed plastically even at the smallest loads, this is not necessarily true of materials having lower elastic modulus. This is confirmed by measurement of the area of contact between a nylon hemisphere and a glass surface, and by frictional measurements on various nylon specimens. It is shown further that the observed decrease in friction of some high polymers on rough surfaces may be explained in terms of elastic deformation of the asperities.