Abstract
A study of the frictional behavior of the irradiated high density polyethylene over a temperature range from about 2O°C up to 200°C is described. In this work it is found that the coefficient of friction μ increases with increasing temperature until about the melting point of this material (the first stage), and above the melting point it decreases to a constant value (the second stage). As an example μ of the highest-irradiated specimen increases at first from .0.4 up to 0.6, and above the melting point it decreases to 0.15. The phenomenon of the first stage becomes more remarkable with increasing radiation dose, but the constant low value of μ at the second stage seems independent of radiation dose. It is suggested that the frictional behaviors of the irradiated polymer at elevated temperatures may be explained not by thedecrease of adsorbed gases on the sliding surface or the change of S/P (S : shearing strength ; P : hardness or yield pressure) of the polymer, but by a deformation factor in sliding friction which was previously described by Tabor. The deformation factor probably consists, here, of the loss caused by the relative displacement of crystallites of polymers surrounded by network chains, which have been produced by irradiation.
