Competition between a and b crystallization in isotactic polypropylene : effect of nucleating agents composition / S.-W. Wang in INTERNATIONAL POLYMER PROCESSING, Vol. XXX, N° 3 (07/2015)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXX, N° 3 (07/2015) . - p. 344-349 Titre : Competition between a and b crystallization in isotactic polypropylene : effect of nucleating agents composition Type de document : texte imprimé Auteurs : S.-W. Wang, Auteur ; Y. T. Leng, Auteur ; J. Jiang, Auteur ; G.-Q. Zheng, Auteur ; Q. Li, Auteur Année de publication : 2015 Article en page(s) : p. 344-349 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cristallisation Nucléation Polymères -- Propriétés mécaniques Polymères isotactiques Polypropylène Rhéologie Index. décimale : 668.9 Polymères Résumé : Based on the different nucleation ability, different contents and proportions of the mixed nucleating agents were melt compounded with pure isotactic polypropylene resins employed in this work, selective ? nucleating agent was a compound of pimelic acid and calcium stearate, the ? nucleating agent was a type of dibenzylidene sorbitol derivative. The competition attributed to the different type of interactions between a nucleating agent and isotactic polypropylene molecular chains during crystallization was investigated in this research. For a low content of the mixed nucleating agents used, ? nucleation dominated the crystallization behavior of isotactic polypropylene, while with an increase of the content of the mixed nucleating agents, the situation was reversed and ? nucleation became dominant. In the ? dominated region, both of the molecular chain and segmental motions were various with different nucleating agent proportion. Thus, the content and proportion of the components of the nucleating agents were the critical factors in the competition during crystallization. Note de contenu : - Material - Sample preparation - Mechanical properties - Differential scanning calorimetry - Wide angle X-ray diffraction - Dynamic rheological analysis DOI : 10.3139/217.3023 En ligne : https://drive.google.com/file/d/1vFky-tZGOnQ3fR-OKDD9ObcWFnGhsGc3/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=24329 [article]

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Effect of hot water and water-carrying agent on the properties of silane-water crosslinked linear low density polyethylene / T. Chen in INTERNATIONAL POLYMER PROCESSING, Vol. XXVIII, N° 2 (05/2013)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVIII, N° 2 (05/2013) . - p. 180-187 Titre : Effect of hot water and water-carrying agent on the properties of silane-water crosslinked linear low density polyethylene Type de document : texte imprimé Auteurs : T. Chen ; J. Wang ; P. Shi ; Q. Li ; C. Wu Année de publication : 2013 Article en page(s) : p. 180-187 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Alun Eau Peroxyde de dicumyle Polyéthylène basse densité linéaire Polymères -- Propriétés mécaniques Polymères -- Propriétés thermiques Réticulation (polymérisation) Vinyltriméthoxysilane Index. décimale : 668.9 Polymères Résumé : The influence of hot water and the water-carrying agent aluminum potassium sulfate dodecahydrate (alum) on the mechanical and thermal properties of the silane-water crosslinked linear low density polyethylene (LLDPE) was investigated. LLDPE was melt-grafted with various content of vinyl trimethoxysilane (VTMS) using dicumyl peroxide (DCP) as initiator. The results show that the contribution of hot water to gel content is poor, about 2 to 16 %, compared with that of the silane grafted LLDPE. Is feasible to achieve silane-water crosslinking reaction with alum for self-crosslinked LLDPE; furthermore, the self-crosslinked LLDPE has lower crosslink density (m). It was found that alum could not only conduct silane-water crosslinking reaction effectively, but also improve the mechanical properties, especially the elongation behavior. The heat of fusion (DHm), the melting temperature (Tm), and the degree of crystallinity (Xc) of the hot water crosslinked LLDPE decreased with the advancement of VTMS. The Avrami exponent n of self-crosslinked sample was larger than that of hot water crosslinked sample. This means that the alum could contribute to the growth of crystallization. Note de contenu : - EXPERIMENTAL : Materials - Silane grafting and water crosslinking of LLDPE - Characterizations - RESULTS AND DISCUSSION : Grafting analysis - Gel content and crosslink density - Mechanical properties - Thermal properties DOI : 10.3139/217.2672 En ligne : https://drive.google.com/file/d/1OG_KmaUmczdSdbQK-aFwHggZaKVHpuB8/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18428 [article]

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Functionalization of PP with sulfonyl azide through reactive processing / Q. Li in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 3 (07/2007)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXII, N° 3 (07/2007) . - p. 311-319 Titre : Functionalization of PP with sulfonyl azide through reactive processing Type de document : texte imprimé Auteurs : Q. Li, Auteur ; C. Tzoganakis, Auteur Année de publication : 2007 Article en page(s) : p. 311-319 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The functionalization of polypropylene (PP) by 4-carboxybenzene sulfonyl azide (CBSA) was investigated in a batch mixer and the reaction was monitored through FTIR, 1H-NMR and XPS spectroscopy. The degree of grafting was found to increase initially with azide feed content and subsequently to level off at azide concentrations of 2wt.%. Experiments performed at different reaction temperatures showed that a maximum degree of grafting was obtained around 190°C. The linear viscoelastic properties the functionalized PPs were also evaluated by oscillatory shear measurements and were found to correlate with the grafting degree results. Finally, the adhesive properties of the functionalized PPs were evaluated through peel tests on aluminum substrates. The peel strength increased with the degree of grafting and it was found to be significantly higher for purified samples than for non-purified ones. Finally, it was demonstrated that the cooling rate of the PP/aluminum laminate specimens had a major effect on the peel strength. DOI : 10.3139/217.2039 En ligne : https://drive.google.com/file/d/1gDbOP0VM1LvXvXjpMetPzqOvvjS_q7LU/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2709 [article]

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Improved layer mechanical properties of micro injection molded PP / S. J. Ma in INTERNATIONAL POLYMER PROCESSING, Vol. XXXII, N° 1 (03/2017)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXII, N° 1 (03/2017) . - p. 138-142 Titre : Improved layer mechanical properties of micro injection molded PP Type de document : texte imprimé Auteurs : S. J. Ma, Auteur ; Shi Wei Wang, Auteur ; Q. Zhang, Auteur ; Q. Li, Auteur Année de publication : 2017 Article en page(s) : p. 138-142 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Engrenages Matières plastiques -- Moulage par micro-injection Matières plastiques -- Propriétés mécaniques Pièces moulées Polymères isotactiques Polypropylène Index. décimale : 668.4 Plastiques, vinyles Résumé : The results have been achieved by adjusting the structure to improve the performance of micro injection molded isotactic polypropylene products. Annealing was adopted to optimize the performance of isotactic polypropylene micro injection molded gears. It was found that the annealing temperature shows greater influence on the crystalline structure of the micro injection molded gears than annealing time. The layer mechanical properties were greatly improved after annealing, about 1.7-fold for modulus and 1.9-fold for hardness of the micro injection molded gears relative to the unannealed sample. This is due to the fact the state of molecular chain aggregation tends to be consistent after high temperature annealing in the micro injection molded isotactic polypropylene gear sample. DOI : 10.3139/217.3349 En ligne : https://drive.google.com/file/d/1LTsymFbJt4nfndAts60EbBs7fbxpwPyp/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28010 [article]

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Influence of process parameters on the morphologies of micro-injection molded polyformaldehyde parts / L.-X. Wang in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 3 (07/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 3 (07/2019) . - p. 367-375 Titre : Influence of process parameters on the morphologies of micro-injection molded polyformaldehyde parts Type de document : texte imprimé Auteurs : L.-X. Wang, Auteur ; D.-F. Wang, Auteur ; Lixia Jiang, Auteur ; N. Bian, Auteur ; Q. Li, Auteur ; C.-Y. Shen, Auteur Année de publication : 2019 Article en page(s) : p. 367-375 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matières plastiques -- Moulage par micro-injection Morphologie (matériaux) Polyoxyméthylène Index. décimale : 668.4 Plastiques, vinyles Résumé : The morphologies of micro-injection molded parts are influenced by the process parameters. In this paper, the influence of injection speed, mold temperature and melt temperature on the morphologies of micro-injection molded polyformaldehyde (POM) parts with different thicknesses were investigated by a single factor experimental method; the morphological structure of the parts was characterized by polarized light microscopy. The scale effect on the crystallization behavior and internal morphology of micro-injection POM parts was analyzed. The results indicated that the scale effect had a great influence on the hierarchical morphology in the thickness direction of the parts. The micro-parts with a thickness of 1.0 mm showed a skin-core structure including the skin layer, fine grain layer, oblate spherulite, and spherulite core layer, and the micro-parts with a thickness of 0.2 mm showed a skin-core structure with the skin layer, fine grain layer, and the spherulite core layer, and a larger thickness ratio of the spherulite core layer. As injection speed, mold temperature and melt temperature increase, the fine grain layer gradually disappears and the size of core spherulite tends to become larger, the thicknesses of the skin layer of all the micro-parts decrease and that of the 0.2 mm micro-parts decreases significantly. Note de contenu : - EXPERIMENTAL PART : Materials - Micro-parts and mold design - Sample preparation and characterization methods - RESULTS AND DISCUSSION : Effect of injection speed on morphological structure of POM micro-injection molded parts - Effect of melt temperature on morphological structure of POM micro-injection parts - Effect of mold temperature on morphological structure of POM micro-injection molded parts DOI : https://doi.org/10.3139/217.3776 En ligne : https://www.degruyter.com/document/doi/10.3139/217.3776/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32898 [article]

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