Carbon deposition and argon post-treatment of polyurethane surface: Structural-mechanical and fracture properties

Abstract

Modification of polymeric surface by plasma ions has perspectives in creating flexible functional materials; their deformation behavior is one of the most important properties, as poor fracture resistance cancels all advantages. Carbon ions were deposited on the surface of elastic polyurethane with subsequent argon treatment. Created carbon-containing nanolayer has increased wettability and nonuniform local mechanical properties. Uniaxial extension to strains >100% induces discontinuous microcracks of carbon-modified surfaces but their propagation is constrained by inhomogeneities of the modified layer. Argon post-treatment improves wettability further but makes local mechanical properties uniform that decreases the fracture resistance. Multi-cycle uniaxial loading to 50% doesn't damage the surface but forms in the modified layer weakened domains – precursors of failure; this improves crack resistance at strains >100% a mesh of disordered microcracks appears preventing propagation of long cracks.