Effect of stick-slip on the scratch performance of polypropylene

• The Delta-L and scratch width can be correlated with the scratch performance.
• A material with poor scratch resistance exhibits a larger periodic stick-slip distance than that with better resistance.
• The periodic stick-slip distance could be used as an evaluation parameter of scratch resistance.

For the scratch process of polypropylene (PP), the stick-slip phenomenon always exists and contributes to the observed periodic surface damage patterns. The stick-slip, one main cause for scratch visibility, alters the surface characteristics of substrate and eventually induces scratch visibility. Both ASTM/ISO and Erichsen scratch test methods are employed to study the stick-slip phenomenon and its effects on scratch behavior of PP. Image analysis shows that the stick-slip phenomenon was responsible for material removal and severe surface damage. Possible solutions to improve the scratch performance of polymeric materials are also discussed in this paper.