Impact strength of B-nucleated polypropylene / M. Obadal in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 1 (03/2004)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 1 (03/2004) . - p. 35-39 Titre : Impact strength of B-nucleated polypropylene Type de document : texte imprimé Auteurs : M. Obadal, Auteur ; R. Cermak, Auteur ; N. Baran, Auteur ; K. Stoklasa, Auteur ; J. Simonik, Auteur Année de publication : 2004 Article en page(s) : p. 35-39 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Structural transformations of semicrystalline polymers form an important field of current scientific research. The preparation of controlled supermolecular structure may lead to significant improvements in mechanical, thermal and optical properties. As for isotactic polypropylene (iPP), its properties essentially depend on its crystalline phase composition, which is due to polymorphism of iPP. Thus, the aim of this work is to analyze the influence of the B-phase content in polypropylene and of its spatial arrangement on mechanical properties, in particular on its impact strength. Commercially available isotactic polypropylene (iPP) was modified by various amounts of a specific B-nucleating agent (N, N’-dicyclohexylnaphtalene-2,6-dicarboxamide). From the prepared mixtures standard impact testing bars were injection molded. The structure of the specimens was studied by X-ray diffractometry, and impact properties were determined using Charpy impact tester. It was found that addition of the nucleator led to B-phase content increase, especially in the core region of the injection molded samples. The skin (surface layer of the samples) contained lower amount of B-phase. Furthermore, notch impact strength dramatically increased with increasing concentrations of the B-nucleating agent. The concentration of 0.03 wt.% of the nucleator can be considered a “boundary value” due to the fact that the maximum notch impact strength value was reached. With further addition of the nucleating agent the impact strength slowly decreased. Therefore it should be noted that the improvement of impact properties is not only due to the presence of B-phase, but also there are some synergy-applied factors – such as the structural heterogeneity and spatial arrangement of the B-phase in injection molded samples DOI : 10.3139/217.1802 En ligne : https://drive.google.com/file/d/1TsgZvexOku8NRqfOK1zZgFSU9GPiji4i/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3293 [article]

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On PVT and rheological measurements of polymer melts / T. Sedlacek in INTERNATIONAL POLYMER PROCESSING, Vol. XX, N° 3 (09/2005)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XX, N° 3 (09/2005) . - p. 286-295 Titre : On PVT and rheological measurements of polymer melts : Correction of the hole fraction-viscosity relationship Type de document : texte imprimé Auteurs : T. Sedlacek, Auteur ; R. Cermak, Auteur ; B. Hausnerova, Auteur ; M. Zatloukal, Auteur ; A. Boldizar, Auteur ; P. Saha, Auteur Année de publication : 2005 Article en page(s) : p. 286-295 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The relation between PVT and rheological measurements of several polymer melts including polyethylenes, polypropylene, polystyrene, poly(methyl methacrylate), and polycarbonate has been taken into investigation. Pressure-temperature dependent viscosities, determined on rotational and backpressuremodified capillary rheometers, were fitted through the Carreau-Yasuda model. PVT data was analyzed by the help of the Simha-Somcynsky equation of state (SS EOS). The thermodynamical parameters of the SS EOS were connected to constantstress viscosity (experimental) and zero-shear viscosity (extrapolated). The Doolittle relationship was modified into the form of eta = C0 exp (C1 ln (h'/h)). The relation was employed and tested for the data evaluation. It proved to be a good tool for linearization of PVT and rheological data. DOI : 10.3139/217.1890 En ligne : https://drive.google.com/file/d/14kdLyE9sVuNFGcf1lzesA_oVBwwWLx7e/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3065 [article]

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Pressure and temperature dependence of LDPE viscosity and free volume : The effect of molecular structure / T. Sedlacek in INTERNATIONAL POLYMER PROCESSING, Vol. XXI, N° 2 (05/2006)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXI, N° 2 (05/2006) . - p. 98-103 Titre : Pressure and temperature dependence of LDPE viscosity and free volume : The effect of molecular structure Type de document : texte imprimé Auteurs : T. Sedlacek, Auteur ; P. Saha, Auteur ; R. Cermak, Auteur ; M. Zatloukal, Auteur ; A. Lengalova, Auteur Année de publication : 2006 Article en page(s) : p. 98-103 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Temperature and pressure dependencies of shear and elongational viscosities were examined using rotational and capillary rheometers. Two different batches of the same polymer grade have shown that the molecular structure diversion significantly influences the magnitudes of pressure coefficients, which vary more than the temperature coefficients. The pressure effect on viscosity notably depends on the amount of long-chain branching in polymer. Further, the paper shows that pVT data analysis via the Simha-Somcynsky equation of state can be employed to reveal differences in temperature and pressure viscosity dependencies through the free volume fraction. DOI : 10.3139/217.1909 En ligne : https://drive.google.com/file/d/1jtQiPDSPz0bU_XPomjoz1W0m4jafYAl5/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2902 [article]

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Tensile and flexural properties of β-nucleated polypropylenes / M. Obadal in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 3 (09/2004)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 3 (09/2004) . - p. 308-312 Titre : Tensile and flexural properties of β-nucleated polypropylenes Type de document : texte imprimé Auteurs : M. Obadal, Auteur ; J. Simonik, Auteur ; K. Stoklasa, Auteur ; V. Habrovà, Auteur ; R. Cermak, Auteur Année de publication : 2004 Article en page(s) : p. 308-312 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Resuming our previous work on B-nucleated polypropylenes, namely on their impact strength, our present work directs attention towards a flexural and tensile behavior of B-nucleated polypropylenes (B-iPP). For the purposes of this work, commercially available isotactic polypropylene was modified using various amounts of a specific nucleating agent based on N, N’-dicyclohexylnaphtalene-2,6-dicarboxamide (NU100). From the prepared blends test specimens were prepared by injection molding. Structural characterization (crystallinity and the content of B-phase) was carried out by X-ray diffractometry. A multipurpose mechanical property tester was used for determination of tensile and flexural properties. It was found that B-phase content decreased both tensile and flexural strength; on the other hand, the presence of B-phase dramatically raised cold drawability of the injection-molded specimens; addition of 0.03 wt.% of NU100 in the injection-molded parts led to a more than 800% increase of the draw ratio of specimens tested at the testing speed of 100 mm/min. Furthermore, tensile testing carried out using various strain speeds (10 and 100 mm/ min) revealed that higher ductility of the material containing B-phase is particularly pronounced by faster deformation processes, such as fast drawing or impact load. DOI : 10.3139/217.1834 En ligne : https://drive.google.com/file/d/11B2PIUR0ZFe6lSuTOar05m9xr9NFwUf1/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3115 [article]

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