Measurement of Mar Resistance and Study of Marring Mechanism of Polymeric Coatings with Scanning Probe Microscope

By Weidian C. Shen, Bin Jiang, Frank N. Jones

A scanning probe microscope (SPM) equipped with a custom-made probe, consisting of a diamond tip and rectangular tungsten cantilever, was used to measure the mar resistance of crosslinked polymeric surface coatings at micron and submicron scales. The term “mar” is used to describe the surface damage of coatings, which may not be readily noticeable individually, how-ever, the existence of many mars does degrade the appearance of coatings.

Good mar resistance is a requirement for many coatings applications. With the unique high resolution of the SPM, the dimension of the mars can be measured with great accuracy, thus different responses of coatings to the marring stress, i.e., elastic recovery, plastic deformation, and abrasive wear, can be identified quantitatively. In addition, the dynamic process of marring, including viscoelastic creep, strain-hardening, micro-cracking, and surface fatigue, has also been studied with the SPM.