Relating scratch resistance to injection molding‐induced morphology of polypropylene

Abstract

ABSTRACT:The relationship between the scratch resistance and the injection molding-induced morphology of polypropylene (PP) was investigated. The crystal structure near the surface was controlled by the mold temperature and the doping of a nucleating agent (NA). Although aand b-NA were used to improve the scratch resistance of PP that was molded at a mold temperature of 40 C, both of the NAs only slightly affected the scratch resistance due to low crystallinity at the surface. When the mold temperature was increased, the skin layer became thin and a bform crystal formed. Plastic deformation under the scratch was limited in the frozen layer. Consequently, the thickness of the frozen layer (which had low crystallinity) had the predominant effect on the scratch resistance in comparison to the polymorphism differences. The crystal morphology was analyzed with synchrotron micro-beam wide angle X-ray diffraction and Fourier transform infrared spectroscopy.

Capability of Scratch Testing − A View on the Influence of Injection Molding, Water Absorption, and Blend Systems of Polymeric Materials

“…Work by other authors already proved the influence of the injection molding process on the scratch resistance of PP samples. Kobayashi and Otsuki for example connects an increased scratch resistance with an increased tool temperature, whereas Chivatanasoontorn and Koji found increasing injection speed, i.e. shear rate, to cause increasing scratch resistance.…”

Experimental and numerical investigations of evaluation criteria and material parameters' coupling effect on polypropylene scratch

“…Polypropylene (PP) has been widely used in automotive industry. The scratch behavior of PP has drawn much attention since the scratch can significantly affect its surface aesthetics . It has been found that crystallinity, additives, molecular weight, etc.…”