Impact of fatigue loading on the surface of polyurethane treated in argon and acetylene plasma

Abstract

Soft plasma-treated polymers have good prospects in the creation of biomedical products. Their application is associated with cyclic mechanical loads. The practical applicability of such coatings is unclear without investigating the effect of deformation on the structure of modified surfaces. Elastic polyurethane (synthetic two-phase polymer) was used in this work. Its surface was preliminarily cleaned from low-molecular fractions by argon plasma and then treated by plasma chemical decomposition of acetylene in argon plasma for 30...120 s. The structural and mechanical inhomogeneities of the obtained carbon-containing nanocoatings depend on the treatment time and were caused by the composition of the initial substrate. Uniaxial fatigue loading leads to the formation of transverse folds on the coatings in the unloaded state (a result of elastic-plastic deformation of the coating); under tension these folds are open and form local nanocracks. One of the variants of plasma modification did not give the formation of cracks; it is associated with the areas with a pronounced stiffness contrast of this coating.