Simulation study of thermotropic LCPs and prediction of nromal stress difference at high shear rate / A. Rahman in INTERNATIONAL POLYMER PROCESSING, Vol. XXVIII, N° 5 (11/2013)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVIII, N° 5 (11/2013) . - p. 470-482 Titre : Simulation study of thermotropic LCPs and prediction of nromal stress difference at high shear rate Type de document : texte imprimé Auteurs : A. Rahman, Auteur ; Rahul K. Gupta, Auteur ; S. N. Bhattacharya, Auteur ; S. Ray, Auteur ; F. Costa, Auteur Année de publication : 2013 Article en page(s) : p. 470-482 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cisaillement (mécanique) Composites à fibres de verre Isotropie L'isotropie caractérise l’invariance des propriétés physiques d’un milieu en fonction de la direction. Le contraire de l’isotropie est l’anisotropie. Modèles mathématiques polymères cristaux liquides Viscosité Index. décimale : 668.4 Plastiques, vinyles Résumé : The shear viscosity and normal stress difference of two filled and two unfilled thermotropic liquid crystal polymer (TLCPs) were studied. The rigid and rod like molecules of TLCPs orientate differently at different shear rates. Under low shear rate, the molecules tend to align in the direction of the flow but also tumble and wagging on their own axis. The abnormal orientation of the molecules also depends upon temperature, fillers contents, aspect ratio and elastic nature of LCP molecules. These behaviors lead to unusual rheological properties of LCPs, such as negative first normal stress difference for filled LCPs at low shear rates. But with the increase of shear rate, the molecules are oriented in the direction of flow, which lead to isotropic flow at high shear rates. The complicated rheological properties and characteristic anisotropic properties of LCPs are modelled by recently developed Leonov’s viscoselastic constitutive equations. Simulation has been carried out using Mathematica software and the characteristic an„isotropic properties of LCPs have been identified. The ex„perimentally measured viscosities at high shear rate have been compared with model predictions. Moreover, the normal stress differences using at high shear rates have been estimated using Leonov’s model, which is experimentally not accessible. Note de contenu : - Normal stress behavior - Orientation of LCP molecule - Fiber interaction in LCP composites - LCPs and fiber orientation in composites - Rheological models for LCPs - Leonov's weak nematic viscoelasticity in absence of magnetic field - Materials - Experiment - Aspect ratio of glass fibre - Simulation of Leonov's model parameters DOI : 10.3139/217.2756 En ligne : https://drive.google.com/file/d/1JPVbfInsdDpifQus6Xojow_aMgICSbZE/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=19893 [article]

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