Influence of crystal structure on thermo-mechanical properties of injection molded B-nucleated iPP / A. Hamza in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 5 (2021) . - p. 545-556 Titre : Influence of crystal structure on thermo-mechanical properties of injection molded B-nucleated iPP Type de document : texte imprimé Auteurs : A. Hamza, Auteur ; R. K. Arya, Auteur ; A. D. Palsodkar, Auteur ; G. R. Bhadu, Auteur ; S. J. A. Rizvi, Auteur Année de publication : 2021 Article en page(s) : p. 545-556 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Agent de nucléation Caractérisation Matériaux -- Propriétés thermomécaniques Matières plastiques Matières plastiques -- Moulage par injection Mélange Polymères -- Propriétés thermomécaniques Polymères isotactiques Polypropylène greffé anhydride maléique Structure cristalline (solide) Thermodurcissables -- Propriétés thermomécaniques Index. décimale : 668.4 Plastiques, vinyles Résumé : Isotactic polypropylene (iPP) was nucleated in-situ with calcium pimelate during melt compounding. Calcium pimelate is a highly effective β-nucleator for isotactic polypropylene (iPP). The β-nucleated iPP was characterized by wide angle x-ray diffraction (WAXD) and differential scanning calorimetry (DSC) for its crystallinity and crystal structure. In addition, the injection-molded samples were tested for thermo-mechanical properties. It is found that very low quantity (< 0.1 wt. %) of β-nucleator is required to produce sufficiently high β-crystal fraction (Kβ) in isotactic polypropylene. β-nucleated iPP shows increment of 11 to 14 °C in its heat deflection temperature (HDT). It was also observed that slow cooling rate of β-nucleated iPP promotes the formation of β-crystals and that tensile stretching leads to complete transformation of β crystals into a-crystals at room temperature. It was also revealed that the presence of maleic anhydride grafted polypropylene (PP-g-MA), a well-known coupling agent (or compatibilizer), may reduce the (Kβ) value to a marginal extent. It was also observed that the thermo-mechanical properties were not much affected by the presence of PP-g-MA. Therefore, calcium pimelate may be used as β-nucleator in case of neat as well as reinforced polypropylene containing maleic anhydride as coupling agent. Note de contenu : - EXPERIMENTAL : Materials - Melt compounding - Injection molding - Testing of molded specimens - RESULTS AND DISCUSSION : Effect of concentration of β-nucleator on thermo-mechanical properties of iPP - Effect of coupling agent (PP-g-ma) on the efficiency of β-nucleator - Stretching induced (β-α) transformation in β-iPP - Table 1 : Injection molding parameters - Table 2 : Crystallinity of neat and 𝛽-iPP at different concentrations of 𝛃-nucleator (calculated from WAXD data) - Table 3 : Crystallinity of neat- and 𝛃-iPP at different concentrations of 𝛃-nucleator (calculated from DSC first heating data) - Table 4 : Results of DSC second heating scan for neat and 𝛃-nucleated iPP - Table 5 : Crystallinity values of 𝛃-iPP with different concentration (wt.%) of PP-g-MA - Table 6 : DSC-second melting and crystallization parameters for 𝛃-nucleated iPP containing coupling agent (PP-g-MA) - Table 7 : Effect of stretching on crystallinity and crystal structure DOI : https://doi.org/10.1515/ipp-2020-4106 En ligne : https://drive.google.com/file/d/1fBkbI5UTQhKXftRExRvGTPuJb7sNbvIl/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36521 [article]

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