Roles of additives in scratch resistance of high crystallinity polypropylene copolymers

Scratch behavior in neat and talc-filled high crystallinity polypropylene (PP) copolymers containing various additives is investigated using a constant load scratch test and two types of indentation tests (Rockwell and Shore D). The talc-filled PP copolymer exhibits high scratch visibility and scratch depth. The addition of a nucleating agent or lubricant improves the scratch resistance of the talc-filled PP copolymer. Differential scanning calorimetry, scanning electron microscopy and attenuated total reflectance Fourier transform infrared spectroscopy are used to characterize crystallinity, morphology and scratch mechanisms in PP systems. It is found that the scratch resistance of the PP copolymer systems investigated, in terms of scratch depth and scratch visibility, depends mainly on the fracture features generated during the scratch process. The influences of talc, nucleating agent and lubricant on the scratch behavior of PP are discussed.