Scratch Behaviour of EPR-Rich TPOS

The scratch behavior of a set of model soft thermoplastic olefin systems containing at least 65 wt% of ethylene-propylene rubber (EPR) in polypropylene was analyzed using a standardized progressive load scratch test. It was found that raising the ethylene content in the EPR introduces crystalline phases, as evidenced by differential scanning calorimetry, and significantly alters the scratch behavior. A strong effect was also observed by changing the rate at which the scratch test was applied. This paper will discuss these effects based on the scratch damage mechanisms observed.