FRICTION PROPERTIES OF ORIENTED CRYSTALLINE POLYMERS

The friction and dynamic properties of oriented crystalline polymers - linear and branched polyethylene - have been investigated at temperatures ranging from -180 to +149°C. Microhardness and dilatometric measurements were made and the structures were studied by x-ray and polarization methods. It is shown that orientation due to extension decreases friction and increases the shear storage modulus at temperatures below the melting range of the polymer. In the melting range orientation disappeared in the specimens and the dependences of friction and dynamic modulus on temperature practically coincide with the analogous dependences for unoriented specimens. The nature of the friction maxima of polyethylenes in the low and high temperature regions is discussed.