In this study the instrumented tensile (ITI) and falling weight impact (IFWI) behavior of injection-molded α- and β-phase polypropylene (PP) homopolymers were compared at ambient temperature in a broad melt flow index (MFI = 0.7-13 dg/min) range. It was found that the toughness of β-PP is superior to the α-PP: the difference between them increased with decreasing MFI or increasing molecular weight (MW). As expected, the injection molding induced skin layer thickness increased with increasing MW. Effects of the skin-core morphology were deduced indirectly by considering the results achieved on specimens molded at low and high injection speeds (vinj = 6 and 150 mm/s), respectively. It was found that the effect of the skin-core structure is markedly stronger under uniaxial in-plane (i.e., ITI) than in biaxial out-of-plane type loading (i.e., IFWI).
|Number of pages||10|
|Journal||Journal of Applied Polymer Science|
|Publication status||Published - Jan 1 1999|
ASJC Scopus subject areas
- Surfaces, Coatings and Films
- Polymers and Plastics
- Materials Chemistry