Analysis of self-reinforced mechanism of over-molding polypropylene parts / Y. Lu in INTERNATIONAL POLYMER PROCESSING, Vol. XXXV, N° 1 (03/2020)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXV, N° 1 (03/2020) . - p. 95-106 Titre : Analysis of self-reinforced mechanism of over-molding polypropylene parts Type de document : texte imprimé Auteurs : Y. Lu, Auteur ; K.-Y. Jiang, Auteur ; M.-J. Wang, Auteur ; Y. Zhang, Auteur ; Y.-Y. Liu, Auteur Année de publication : 2020 Article en page(s) : p. 95-106 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse thermique Calorimétrie Composites thermoplastiques auto-renforcés Essais dynamiques Matières plastiques -- Moulage par micro-injection Matières plastiques -- Propriétés mécaniques Matières plastiques -- Surmoulage Microscopie Morphologie (matériaux) Polypropylène Structure cristalline (solide) Traction (mécanique) Index. décimale : 668.4 Plastiques, vinyles Résumé : On the premise that the overall structure and composition of the parts remain unchanged, the over-molding of self-reinforced polymer composites parts (OM-SRCs parts) prepared in this paper change the aggregation structure of the parts by combining multi-component sequential molding technology with micro-injection molding technology. Thus, it improves the comprehensive performance of the parts, and achieves the purpose of self-reinforcing. The morphological feature of self-reinforced parts during over-molding are obviously different from those formed by conventional injection molding, which also leads to differences in physical properties. In this study, two types of polypropylene parts of the same size (60 × 12 × 2 mm3) were prepared, and their micro-morphologies comparison were investigated by means of polarized light microscopy (PLM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). From the results, it was found that the tensile properties of OM-SRCs parts were improved by up to 9.46% compared with the conventional parts. Through PLM observation, it is found that the section shape of OM-SRCs parts perpendicular to the flow direction shows a double “skin-core” structure, resulting in the increase of the area ratio of skin layer to 24% (16% in conventional parts). SEM was carried out on the skin layer near the fusion position of the interface, and a highly oriented “shish-kebab” structure was observed. Through DSC and 1D-WAXD pattern analysis, it was found that the overall crystallinity of OM-SRCs parts decreased by 8.53% and 5.32% compared with the conventional parts, respectively. The 2D-WAXD pattern analysis showed that the molecular orientation degree of the skin layer of OM-SRCs parts increased by 15.65%. By means of the response surface method, the molecular orientation obtained was the decisive factor affecting the performance of OM-SRCs parts. By means of the least squares' minimization procedure, a dimensionless equation between the micro-morphologies and mechanical properties was established, which makes the “adjustability” of the sample performance be preliminarily realized. Note de contenu : - EXPERIMENTAL : Sample material - Sample size - Sample preparation - Tensile test - Polarized light microscopy (PLM) - Scanning electronic microscopy - Differential scanning calorimetry - Wide-angle x-ray diffraction analysis (WAXD) - RESULTS AND DISCUSSION : Mechanical properties - Microscopic observation - Polycrystalline composition and crystallinity - Crystalline molecular orientation - Morphology-mechanical properties relationship DOI : https://doi.org/10.3139/217.3872 En ligne : https://drive.google.com/file/d/14hDR4r6sRbCkxUGsInR-Y-6Dv0l2BiuQ/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33782 [article]

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