Simultaneous biaxial stretching of polypropylene resins of varying tacticity / L. Capt in INTERNATIONAL POLYMER PROCESSING, Vol. XX, N° 4 (12/2005)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XX, N° 4 (12/2005) . - p. 369-379 Titre : Simultaneous biaxial stretching of polypropylene resins of varying tacticity : Part II : Film morphology and properties Type de document : texte imprimé Auteurs : L. Capt, Auteur ; S. Rettenberger, Auteur ; H. Münstedt, Auteur ; Musa R. Kamal, Auteur Année de publication : 2005 Article en page(s) : p. 369-379 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The simultaneous biaxial stretching behavior of three Ziegler-Natta-based isotactic polypropylene resins of varying isotacticity was studied using a laboratory film stretcher that simulates closely stretching conditions encountered in the commercial process. The effect of isotacticity on the final morphology and end film properties was associated with the effect of isotacticity on the thermal properties of the resin. The results showed that the degree of undermelting, (delta) Tum = Tm–T, determines the phase composition of the polymer before stretching and the morphology and orientation of the stretched films. The size and orientation of the crystallites in the stretching plane is mostly determined by the degree of undermelting. The elongation at break was correlated with the residual crystallinity of the film before stretching, and the elastic modulus was correlated with the final degree of crystallinity and the density of tie chains. En ligne : https://drive.google.com/file/d/1tgOrSORI2P-gqkg5hc4mXcpKqBvAhkXa/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2962 [article]

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Simultaneous biaxial stretching of PP resins of varying / L. Capt in INTERNATIONAL POLYMER PROCESSING, Vol. XX, N° 1 (03/2005)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XX, N° 1 (03/2005) . - p. 35-46 Titre : Simultaneous biaxial stretching of PP resins of varying : Tacticity melting and deformation behavior Type de document : texte imprimé Auteurs : L. Capt, Auteur ; S. Rettenberger, Auteur ; H. Münstedt, Auteur ; Musa R. Kamal, Auteur Année de publication : 2005 Article en page(s) : p. 35-46 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The melting and simultaneous biaxial stretching behavior of three Ziegler-Natta isotactic polypropylene resins of varying isotacticity was studied. DSC melting experiments showed that the crystallinity and melt stability of the crystalline phase depend strongly on tacticity and on the degree of undermelting, Delta T = Tm–T, where Tm is the melting temperature. The level of biaxial yield stress depends on the fraction of residual "unmolten" crystallinity and the crystallite size. For specimens with same thermal history, the post-yield deformation shows strong dependence on the degree of undermelting, delta T. The deformation homogeneity and the resulting film thickness may be related to the thermal mobility of the chains and the tie chain and entanglement densities. DOI : 10.3139/217.1867 En ligne : https://drive.google.com/file/d/1DSnN2JaRS7LdBD_xx8Ox7uBm2a7BMBa6/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3088 [article]

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The pressure-volume-temperature behavior polyethylene melts / L. Capt in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 1 (03/2000)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XV, N° 1 (03/2000) . - p. 83-94 Titre : The pressure-volume-temperature behavior polyethylene melts Type de document : texte imprimé Auteurs : L. Capt, Auteur ; Musa R. Kamal, Auteur Année de publication : 2000 Article en page(s) : p. 83-94 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The pressure-volume-temperature (PVT) melt behavior of 12 polyethylene resins was evaluated at pressures up to 200 MPa, using both isothermal and isobaric measurements in a GNOMIX high pressure dilatometer. The resins included high density polyethylene (HDPE), low density polyethylene (LDPE) and linear low density polyethylene (LLDPE). They were produced using a variety of catalysts, including Ziegler-Natta (ZN) and metallocene catalysts. The PVT data were used to evaluate two empirical equations of state (the Tate and Inverse Volume equations) in predicting PVT behavior of the melt, the isothermal compressibility, and the thermal expansion coefficient. The dependence of the melting and crystallization temperatures on pressure was also evaluated, and compared to existing equations. It was not possible to identify structural effects on the PVT melt behavior, as well as the isothermal compressibility and thermal expansion coefficient. However, some slight dependence on density was observed for the parameters of the equations of state. The isobaric experiments revealed that the pressure effect on the melting and crystallization temperatures was similar for all resins. While the melting and crystallization temperatures varied widely for the various resins, the pressure coefficients of the melting and crystallization temperatures were approximately equal (0.25°C/MPa.) The main differences in the behavior of the resins were in the transitional region during melting and crystallization. Note de contenu : - BACKGROUND : Pressure-volume-temperature measurement - Equations of state - The modified tait equation - Compressibility and thermal expansion coefficient - Pressure dependence of melting and solidification temperatures - EXPERIMENTAL : Polyethylene resin properties - Pressure-volume-temperature apparatus - Sample preparation - Calibration - EXPERIMENTAL METHODS : Isothermal measurements - Isobaric measurements - DATA ANALYSIS : Determination of the additional volume - Determination of the melt and solid state regions - Determination of the parameters of the tait equations - Determination of the parameters of the inverse volume equation - Isobaric measurements - RESULTS AND DISCUSSION : Isothermal behavior - Tait equation - Inverse volume equation - Isothermal compressibility and thermal expansion coefficient - Isothermal compressibility - Thermal expansion coefficient - Pressure dependence of crystallization and melting - Pressure dependence of Tm and Tc DOI : 10.3139/217.1576 En ligne : https://drive.google.com/file/d/1XHpL0HmftmPkLmq2qbdkL9HGAFqbflc-/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16077 [article]

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