Internal friction measurement on polymers by low-frequency cyclic Vickers microindentation test

The internal friction characterising the viscoelastic properties of ultra high molecular weight polyethylene (PE) was investigated by applying cyclic Vickers microindentation tests. With the technique explained in the paper the internal friction of polymers can be studied under constant average external stress. The internal friction of polyethylene was investigated as a function of the average load, of the load amplitude and of the loading rate. Changes have been found in the internal friction behaviour after heat treatment and after surface modification.