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Analysis of shrinkage development of a semicrystalline polymer during injection molding / Santis De Felice in Industrial & engineering chemistry research, Vol. 49 N° 5 (Mars 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 5 (Mars 2010) . - pp. 2469–2476 Titre : Analysis of shrinkage development of a semicrystalline polymer during injection molding Type de document : texte imprimé Auteurs : Santis De Felice, Auteur ; Roberto Pantani, Auteur ; Vito Speranza, Auteur Année de publication : 2010 Article en page(s) : pp. 2469–2476 Note générale : Idustrial Chemistry Langues : Anglais (eng) Mots-clés : Polymers;  Semicrystalline Résumé : The phenomenon of shrinkage in injection molding is particularly relevant for the processing of semicrystalline polymers. Nevertheless, if compared with the considerable effort spent by researchers to investigate the evolution of shrinkage and thermal stresses in amorphous polymers, the research work devoted to shrinkage of semicrystalline polymers is rather limited in the literature. In this work, the influence of holding pressure and time, and geometric constraints, on the shrinkage of a semicrystalline polymer was explored. Adopting a technique based on strain gauges, the time at which shrinkage started inside the mold was measured as a function of the holding pressure. Experimental results were compared with predictions for shrinkage obtained by a code developed at the University of Salerno, which takes into account crystallization kinetics and the effect of crystallinity on material properties. In particular, a solidification criterion based on the degree of crystallinity was identified Note de contenu : Bibliogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901316p [article] Analysis of shrinkage development of a semicrystalline polymer during injection molding [texte imprimé] / Santis De Felice, Auteur ; Roberto Pantani, Auteur ; Vito Speranza, Auteur . - 2010 . - pp. 2469–2476. Idustrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 5 (Mars 2010) . - pp. 2469–2476 Mots-clés : Polymers;  Semicrystalline Résumé : The phenomenon of shrinkage in injection molding is particularly relevant for the processing of semicrystalline polymers. Nevertheless, if compared with the considerable effort spent by researchers to investigate the evolution of shrinkage and thermal stresses in amorphous polymers, the research work devoted to shrinkage of semicrystalline polymers is rather limited in the literature. In this work, the influence of holding pressure and time, and geometric constraints, on the shrinkage of a semicrystalline polymer was explored. Adopting a technique based on strain gauges, the time at which shrinkage started inside the mold was measured as a function of the holding pressure. Experimental results were compared with predictions for shrinkage obtained by a code developed at the University of Salerno, which takes into account crystallization kinetics and the effect of crystallinity on material properties. In particular, a solidification criterion based on the degree of crystallinity was identified Note de contenu : Bibliogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901316p

Process - induced morphology distribution in injection molded syndiotactic polystyrene samples / Roberto Pantani in Industrial & engineering chemistry research, Vol. 51 N° 33 (Août 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 33 (Août 2012) . - pp. 10840-10847 Titre : Process - induced morphology distribution in injection molded syndiotactic polystyrene samples Type de document : texte imprimé Auteurs : Roberto Pantani, Auteur ; Andrea Sorrentino, Auteur ; Vito Speranza, Auteur Année de publication : 2012 Article en page(s) : pp. 10840-10847 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Morphology Résumé : In this work, syndiotactic polystyrene was injection molded with different molding conditions. The morphology distribution inside the molded parts was analyzed by several techniques, including optical microscopy, IR spectroscopy, and X-ray diffraction. The final morphology distribution was found to be strongly affected by mold temperature and holding pressures. A peculiar morphology distribution, an alternation of several amorphous and crystalline layers, was found along the samples thickness. The experimental results were analyzed and discussed by means of a software code developed at the University of Salerno. The software implements a model for crystallinity evolution that is able to consider the effects of high cooling rates and high pressures. Furthermore, the software is able to predict the orientation evolution during the injection molding. On commenting on the differences between the experimental data and the model predictions for crystallinity and orientation, it was possible to gain some insights on the causes of the peculiar morphology distributions inside the molded samples. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26286458 [article] Process - induced morphology distribution in injection molded syndiotactic polystyrene samples [texte imprimé] / Roberto Pantani, Auteur ; Andrea Sorrentino, Auteur ; Vito Speranza, Auteur . - 2012 . - pp. 10840-10847. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 33 (Août 2012) . - pp. 10840-10847 Mots-clés : Morphology Résumé : In this work, syndiotactic polystyrene was injection molded with different molding conditions. The morphology distribution inside the molded parts was analyzed by several techniques, including optical microscopy, IR spectroscopy, and X-ray diffraction. The final morphology distribution was found to be strongly affected by mold temperature and holding pressures. A peculiar morphology distribution, an alternation of several amorphous and crystalline layers, was found along the samples thickness. The experimental results were analyzed and discussed by means of a software code developed at the University of Salerno. The software implements a model for crystallinity evolution that is able to consider the effects of high cooling rates and high pressures. Furthermore, the software is able to predict the orientation evolution during the injection molding. On commenting on the differences between the experimental data and the model predictions for crystallinity and orientation, it was possible to gain some insights on the causes of the peculiar morphology distributions inside the molded samples. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26286458