Instrumented tensile and falling weight impact response of injection-molded α- and β-phase polypropylene homopolymers with various melt flow indices
✍ Scribed by J. Karger-Kocsis; D. E. Mouzakis; G. W. Ehrenstein; J. Varga
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 405 KB
- Volume
- 73
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
In this study the instrumented tensile (ITI) and falling weight impact (IFWI) behavior of injection-molded ␣and -phase polypropylene (PP) homopolymers were compared at ambient temperature in a broad melt flow index (MFI ϭ 0.7-13 dg/min) range. It was found that the toughness of -PP is superior to the ␣-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 (v inj ϭ 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).