Properties of ultra‐high‐molecular‐weight polyethylene with a structure modified by plastic deformation and electron‐beam irradiation

Abstract

AbstractTo improve the functional properties of polyethylene in a polymer–metal kinematic system, ultra‐high‐molecular‐weight polyethylene (UHMWPE) was subjected to light deformation by uniaxial compression [permanent true strain (ef) = 0.14–0.32] and postdeformation electron‐beam irradiation (with a dose of 26–52 kGy). X‐ray examinations demonstrated that no significant reorientation of the lamellar structure occurred upon compression. The textures of all of the samples, except for the sample deformed at ef = 0.32, were nearly random. In the exception, a very weak axial texture developed. However, the treatment applied (deformation and electron‐beam irradiation) significantly changed the structure of the material. A considerable increase in the crosslinked fraction and the crystalline band absorption in the Fourier transform infrared spectra were observed in the modified samples. This indicated a noticeable increase in the degree of spatial ordering within a structure, although the overall crystallinity increased only slightly. The effect of such restructuring was evidenced by microscopic observations of the near‐surface layer of the UHMWPE samples subjected to unidirectional sliding interaction with a CoCr alloy for 100 h (in a block‐ring tribological system). It was found that for the predeformed (ef = 0.14–0.21) and electron‐irradiated (dose of 52 kGy) samples, the operational load imposed on the system resulted in a considerable reduction in the thickness of the plastically deformed near‐surface layer and in a decreasing amount of lamellae oriented flat‐on compared to the neat unmodified UHMWPE subjected to the same test. The recorded tribological wear (mass decrement) decreased up to fivefold in comparison to that of the initial material. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012