Polymers and Polymer Composites

PROCESSING-INDUCED MORPHOLOGY: ITS RELATIONSHIP WITH TENSILE-IMPACT BEHAVIOUR IN INJECTION-MOULDED POLYPROPYLENE

June 1, 2006 By: LaFranche E; Brassart G; Krawczak P Research article

Title: PROCESSING-INDUCED MORPHOLOGY: ITS RELATIONSHIP WITH TENSILE-IMPACT BEHAVIOUR IN INJECTION-MOULDED POLYPROPYLENE
Page Range: p.563-576
Author(s): LaFranche E; Brassart G; Krawczak P
File size: 296K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 14
Issue No: No. 6

Abstract
The main parameters influencing the tensile-impact strength of injection moulded propylene during high volume manufacturing of automotive parts, have been identified. A Taguchi Design of Experiments analysis showed that the key parameters n both flow and transverse directions were the polymer melt and mould temperatures, and the volumetric flow rate. differences in high-speed mechanical behaviour are explained on the basis of an investigation of the processing-induced morphology/tensile-impact behaviour relationship. An through-the-thickness analysis was made of the microstructure of parts manufactured under two extreme sets of moulding conditions by means of microscopy and crystallinity measurement, molecular orientation and thermal expansion. It was found that the brittleness of the injection moulded part depended on the skin layer’s morphology, the main influential parameters being the skin/core ratio and the crystalline structure. The crack initiation energy increased wit the oriented skin layer thickness, whereas the brittleness increased with the crystallinity level and the spherulite size. 30 refs.


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