Scratching of a coated polymer and mechanical analysis of a scratch resistance solution

In the case of polymer scratching, there is no models at all which take into account the viscoelastic viscoplastic behaviour of the material and the ability of polymers to strain harden or soften. Progress has now been made using numerical simulation and a new experimental set-up. When a viscoelastic contact generates a viscoelastic groove, the recovery is sensitive to the high local strain introduced by a geometric discontinuity like the roughness of the grooving tip or the angle between two faces of the tip. The scratch resistance conferred by a coating is evident on both the macroscopic scale of the contact and the local scale of the roughness of the tip. On the local scale, the coating prevents the roughness of the tip from creating micro-scratches at the surface of the macro-groove. Therefore, since the absence of micro-scratches is a condition for relaxation of the macro-groove, the thickness of the coating must be greater than the roughness of the tip. On the macroscopic scale, the mechanical behaviour of the contact is modified by the decrease in the friction coefficient.