Frictional Properties of Irradiated Linear Polymers

Abstract

In this paper, the dose dependence and the load dependence of friction, and also the relation between the coefficient of friction μ and S/P (S : shearing strength ; P : hardness or yield pressure), of linear polymers irradiated by cobalt-60 γ-ray, from 5×10⁷ r up to 2.5×10⁹ r, including non-irradiated specimens, are examined. The μ of crosslinking polymers of polyamide and high density polyethylene increases from two to four times, and that of low density polyethylene decreases gradually to about one half that of the non-irradiated specimen, with increasing radiation dose, and the increase of that of degradated polymers of fluorocarbons is less than above. The dose dependence curve of coefficient α, which is decided by μ∝W^-α, is similar to the reversed curves of those of stiffness, hardness and shearing strength. The μ and S/P are nearly in accord qualitively, but not quantitatively.