Analysis of film blowing with flow-enhanced crystallization / L. K. Henrichsen in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 2 (05/2007)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXII, N° 2 (05/2007) . - p. 179-189 Titre : Analysis of film blowing with flow-enhanced crystallization : Part 1. Steady-state behavior Type de document : texte imprimé Auteurs : L. K. Henrichsen, Auteur ; A. J. McHugh, Auteur Année de publication : 2007 Article en page(s) : p. 179-189 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : An analysis of the steady-state film blowing process based on a two-phase constitutive model that accounts for flow-enhanced crystallization is presented. The amorphous melt phase is represented by a multi-mode Giesekus constitutive equation with a transformation-dependent relaxation time and the semi-crystalline phase is represented by a rigid rod model. The relaxation times in the two constitutive equations are linked by an Avrami, temperature-dependent rate expression which contains a term in the Helmholtz free energy to account for flow-enhancement. Comparisons are made to experimental data for film blowing of linear low density (LLDPE) and low density (LDPE) polyethylenes. Excellent fits for the bubble radius, temperature, and crystallinity are shown. It is also shown that the ratio of amorphous stress to total stress at the "lock-in" point provides an excellent correlating variable for the elongation to break and yield strength properties of the as-blown film. Inclusion of multiple relaxation times in the Giesekus model offers insights on the controlling role of the maximum relaxation time in the stress profiles and locking-in behavior due to crystallization. DOI : 10.3139/217.1003 En ligne : https://drive.google.com/file/d/1QZGOhsT9_u02qLQSHDjzhuZRC0hdZvlm/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2758 [article]

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Analysis of film blowing with flow-enhanced crystallization / L. K. Henrichsen in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 2 (05/2007)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXII, N° 2 (05/2007) . - p. 190-197 Titre : Analysis of film blowing with flow-enhanced crystallization : Part 2. Linearized sensitivity and stability behavior Type de document : texte imprimé Auteurs : L. K. Henrichsen, Auteur ; A. J. McHugh, Auteur Année de publication : 2007 Article en page(s) : p. 190-197 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : An analysis of the transient film blowing process is presented based on the two-phase Giesekus/rigid rod model for flow-enhanced crystallization described in Part 1 [1]. Linearized frequency analysis has been used to explore the effects of system disturbances on the process. Results show that perturbations related to heat transfer and inflation pressure are more significant than the effects of film thickness (die swell). In addition, crystallinity is shown to have a consistent stabilizing effect on the system, with more crystallinity dampening the perturbations. Stability diagrams for each material show relatively wide regions of convergence in the blow-up ratio (BUR) – draw ratio space, however, at higher BURs (≥~4) the system becomes unstable for all DRs. DOI : 10.3139/217.1004 En ligne : https://drive.google.com/file/d/1D3duT4vuT_0XE5bmGQ1oT99c6NdZ6R1t/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2759 [article]

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Dry spinning of polymer fibers in ternary systems / Z. Gou in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 3 (09/2004)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 3 (09/2004) . - p. 244-253 Titre : Dry spinning of polymer fibers in ternary systems : Part I : Model development and predictions Type de document : texte imprimé Auteurs : Z. Gou, Auteur ; A. J. McHugh, Auteur Année de publication : 2004 Article en page(s) : p. 244-253 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : This paper addresses the development and application of a two-dimensional, three component model for the dry spinning process of polymer fibers. The model presented is an expansion of a previously developed two-component dry spinning model [1] that incorporated both viscous and viscoelastic effects in the constitutive equation for the spin fluid, along with two-dimensional effects to account for radial variations in the fiber temperature and composition profiles along the spin line. The model presented in this paper includes the effects of water in the spin dope through incorporation of the diffusion equations for ternary mass transfer. Mass and energy balances on the gas side are also taken into account so that the effects of ambient conditions can be investigated. Calculations are based on the system: cellulose acetate-acetone-water. Results are presented for profiles of solvent concentration, temperature, and glass transition temperature profiles for typical industrial operating conditions. Force and stress distributions in the fiber at various points along the spinline, analyzed in terms of contributions from the viscoelastic and viscous terms in the constitutive equation, illustrate the role of these stresses in the freezing in of structure along the spinline. Model predictions are shown to be in good agreement with the principal characteristics of dry spinning. DOI : 10.3139/217.1831 En ligne : https://drive.google.com/file/d/16_9WSZiSiLR93IhtNRwLdfbDVu1bIryG/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3106 [article]

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Dry spinning of polymer fibers in ternary systems / Z. Gou in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 3 (09/2004)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 3 (09/2004) . - p. 254-261 Titre : Dry spinning of polymer fibers in ternary systems : Part II. Data correlation and predictions Type de document : texte imprimé Auteurs : Z. Gou, Auteur ; A. J. McHugh, Auteur Année de publication : 2004 Article en page(s) : p. 254-261 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : In this work, predictions based on the 2D dry spinning model developed in Part I of this work [2] along with a die swell subroutine supplied by an industrial company, are used to compare with fiber concentration and elongation to break data from an industrial spinline. Die swell ratio predictions agree well with measured values and solidification along the spinline is shown to be due to homogeneous glass transition in the absence of phase separation. Concentration profiles along the spinline are well fit by the model using previously determined prefactors for the diffusion coefficients. A good correlation of elongation at break data is found to occur with a characteristic variable O GTP, the ratio of the rheological force of the viscoelastic Giesekus contribution to the total rheological force (Giesekus + viscous) at the glass transition point. Moreover, the regression obtained from this fit can be further used to make predictions for elongation at break under different operating conditions. Finally, the effects of spinning conditions and model parameters on fiber mechanical properties were investigated. DOI : 10.3139/217.1832 En ligne : https://drive.google.com/file/d/1_mppU7HOBOhbNPy0B-tZn51VJLoMFTtE/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3107 [article]

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