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Induced morphologies in injection moulded parts of polyolefine

Abstract : Research works attempt today to predict the mechanical properties induced by processing of semi-crystalline polymers using the mechanics of heterogeneous media. But the use of these micromechanical models requires a dimensional description of crystalline morphology, as much at the lamellar level as in the higher scale of the induced crystalline macrostructures. In this scientific context, this work gave for objective to finely characterize the morphologies which could be found through the thickness of injection moulded plates of polypropylene and linear polyethylene, and to determine the influence of some processing parameters on these morphologies. The orientation functions of the different crystallographic axes were determined by infrared dichroism and WAXS pole figures obtained with rotating anode generated beam and synchrotron micro-beam. The lamellar distribution and dimensions were determined by SAXS. Finally, the crystalline structures size was characterized by polarized light optical microscopy. The whole of the results was used to generate morphological models through the thickness of the injection moulded plates. Complex morphological structures, induced by deformation, were found: shish-kebabs with epitaxial grow of daughter lamellae for PP and with twisted to right lamellae for HDPE. More generally, the orientation of the amorphous phase is low and the anisotropy of the mechanical properties of polyolefins is controlled by the high orientation of the crystalline phase. The plate thickness and the polymer molecular weight have a strong influence on the molecular orientation and on the obtained crystalline morphologies, whereas the injection speed determines the thickness of the various morphological layers through the thickness, without appreciably modifying neither the molecular orientation levels, nor the lamellar dimensions.
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Submitted on : Friday, July 1, 2005 - 8:00:00 AM
Last modification on : Wednesday, July 25, 2018 - 1:23:45 AM
Long-term archiving on: : Thursday, September 30, 2010 - 6:55:42 PM


  • HAL Id : pastel-00001314, version 1



Rennan Alfonso Mendoza Monroy. Induced morphologies in injection moulded parts of polyolefine. Engineering Sciences [physics]. Arts et Métiers ParisTech, 2005. English. ⟨NNT : 2005ENAM0006⟩. ⟨pastel-00001314⟩



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