Aller sur edunet
Accueil
Détail de l'auteur
Auteur Rahul K. Gupta
Commentaire :
RMIT University - Melbourne - Australia
|
Documents disponibles écrits par cet auteur
Ajouter le résultat dans votre panier Affiner la rechercheA constitutive analysis of extensional flow of EVA nanocomposites / V. Pasanovic-Zujo in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 4 (12/2004)
Titre : A constitutive analysis of extensional flow of EVA nanocomposites Type de document : texte imprimé Auteurs : V. Pasanovic-Zujo, Auteur ; Rahul K. Gupta, Auteur ; S. N. Bhattacharya, Auteur Année de publication : 2004 Article en page(s) : p. 388-394 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Linear and nonlinear oscillatory and extensional flow was studied for polymer layered silicate nanocomposites of organically modified bentonite in ethylene-vinyl acetate copolymer with 18 wt.% of vinyl acetate (EVA18). It was found that the rheological properties of EVA18 nanocomposites were distinctly different from the pure copolymer. The elastic response at low frequencies was significantly enhanced in comparison to that of pure EVA18. The linear to nonlinear transition for stress relaxation measurements and the damping function were examined. The relaxation spectrum was shifted toward the longer relaxation time scales for EVA18 nanocomposites, while the dependence of the damping for EVA18 nanocomposites was much stronger than that of the EVA18. In contrast, the uniaxial extensional viscosity of EVA18 nanocomposites gave weaker strain-hardening properties. The prediction of strain-hardening behaviour for EVA18 and EVA18 nanocomposites through relaxation spectrum and the damping function based on Kaye-Bernstein-Kearsley-Zapas (K-BKZ) model is discussed. A simplified estimation of the nonlinear material parameter b in the K-BKZ model is proposed to predict more accurately the extensional viscosity for EVA18 and EVA18 nanocomposites. Experimental data and detailed predictions are also presented in this paper. DOI : 10.3139/217.1856 En ligne : https://drive.google.com/file/d/11E7c-19HMx8lCQWSwVLcB7rEHRq2OzNL/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3272
in INTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 4 (12/2004) . - p. 388-394[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 001030 - Périodique Bibliothèque principale Documentaires Disponible
Titre : Effect of clay on thermal, mechanical and gas barrier properties of biodegradable polylactic acid/ polybutylene succinate (PLA/PBS) nanocomposites Type de document : texte imprimé Auteurs : A. Bathia, Auteur ; Rahul K. Gupta, Auteur ; S. N. Bhattacharya, Auteur ; H. J. Choi, Auteur Année de publication : 2010 Article en page(s) : p. 5-14 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : A series of poly(lactic acid) (PLA)/poly(butylene succinate) (PBS)/layered silicate nancomposites were prepared by simple melt extrusion of PLA/PBS/Cloisite 30BX (organically modified MMT) clay. Extruded and compression moulded samples containing 1, 3, 5, 7 and 10 wt.% of clay having 80 and 20 wt.% of PLA and PBS respectively, were prepared to investigate morphological, thermal, mechanical and gas barrier properties of these biodegradable nanocomposites. Wide angle X-ray diffraction (WAXD) was used to assess the periodic distance of the clay layers. WAXD indicated an exfoliated structure for nanocomposites containing 1 and 3 wt.% of C30BX, while, dominantly intercalated structures were noticed for nanocomposites having 5, 7 and 10 wt.% of C30BX. Transmission Electron Microscopy (TEM) images confirmed mixed morphology of intercalated and exfoliated structure even for nanocomposites having 1 and 3 wt.% of C30BX, while some clusters or agglomerated tactoids were detected for higher clay containing (>3 wt.%) nanocomposites. Thermo gravimetric analysis (TGA) revealed the thermal stabilities of polymer blend and their nancomposites. Nanocomposite with 3 wt.% C30BX clay showed enhanced thermal stability compared to other nanocomposites. The effect on the crystallinity, investigated by Modulated Differential Scanning Calorimetry (MDSC) showed slight improvement for nanocomposites having 1, 3, 7 and 10 wt.% of C30BX studied. However, nanocomposites having 5 wt.% of clay content showed higher crystallinity compared to the rest of the nanocomposites. Mechanical properties (tensile strength, % elongation at break and Young's modulus) were measured by Instron Universal Testing Machine. Tensile strength and Young's modulus initially increased for nanocomposites of up to 3 wt.% of clay but then decreased with the introduction of more clay. Oxygen permeabilities of the nanocomposites were also measured. Barrier properties were improved by approximately 26% with the increase of clay content in these nanocomposites. DOI : 10.3139/217.2214 En ligne : https://drive.google.com/file/d/1S1aB3S1540iSoCYBmFFGhKAhlep7UbL8/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8577
in INTERNATIONAL POLYMER PROCESSING > Vol. XXV, N° 1 (03/2010) . - p. 5-14[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 012006 - Périodique Bibliothèque principale Documentaires Disponible
Titre : Mechanical properties of rubber-toughened post-industrial glass-fiber-reinforced PA 66 Type de document : texte imprimé Auteurs : F. D. Alsewailem, Auteur ; Rahul K. Gupta, Auteur Année de publication : 2006 Article en page(s) : p. 189-197 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : When compounding engineering thermoplastics with glass fibers for reinforcement purposes, a tremendous amount of polymer-containing waste is generated. However, the polymer of interest is usually commingled with the polymer used to purge the extruder. Reclaiming valuable polymer from this waste is hindered by the incompatibility with the purging material since this leads to a blend system that has poor mechanical properties and low economic value. For this reason, this potentially valuable post-industrial polymer-waste is normally land filled. The current research is directed at the characterization and reuse of a post-industrial PA 66 filled with glass fibers; this was separated from LDPE purge material and its impact resistance was modified through rubber toughening.
Styrene-Ethylene-Butylene-Styrene and Ethylene-Propylene elastomers grafted with maleic anhydride (SEBS-g-MA and EP-g-MA respectively) were used as the toughening agents in this study due to their compatibility with PA. Izod impact strength, tensile strength and modulus, flexural strength, and elongation at break were used to characterize mechanical properties of the rubber-toughened recycled glass-filled PA 66. The morphology of the fracture surfaces of the composites was examined by Scanning Electron Microscopy (SEM). It was found that both impact strength and elongation at break increase with increasing rubber content while flexural strength and tensile strength suffer upon incorporating rubber; however, by adding moderate amounts of rubber to the recycled glass-fiber-reinforced PA 66 a balance between stiffness and toughness of the material could be obtained. For example, the addition of 10 wt.% of SEBS-g-MA to the recycled PA 66 with 23.62 wt.% glass fiber loading resulted in a 27% and 151% increase in tensile strength and impact strength respectively of the blends when compared with neat PA 66. This suggests that compounding both glass fibers and elastomers with PA 66 is a useful strategy to recycle PA 66, especially for reuse in under-the-hood automotive applications.DOI : 10.3139/217.0117 En ligne : https://drive.google.com/file/d/1R-TfVHshvx3RF56LKPCqJ7uurYz-glfO/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2914
in INTERNATIONAL POLYMER PROCESSING > Vol. XXI, N° 2 (05/2006) . - p. 189-197[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 004675 - Périodique Bibliothèque principale Documentaires Disponible
Titre : Melt strength and thermal properties of organic peroxide modified virgin and recycled HDPE Type de document : texte imprimé Auteurs : H. B. Parmar, Auteur ; S. N. Bhattacharya, Auteur ; Rahul K. Gupta, Auteur Année de publication : 2008 Article en page(s) : p. 200-207 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Commercial blow moulding grade recycled high density polyethylene (r-HDPE) and blow moulding grade virgin HDPE were reactively extruded with various compositions (0.00 to 0.15%) of different peroxides in a twin screw extruder. The aim was to improve the melt strength properties of a blow moulding grade HDPE homopolymer – a polymer resin comprising a significant part of the post consumer recycled plastic stream in Australia. Melting behaviour and crystallinity were investigated by modulated differential scanning calorimetry (MDSC). Uniaxial melt extensional (UME) measurement of the modified materials was carried out using Göttfert Rheotens melt strength tester to measure melt quality of the material. Melt strength and zero shear viscosity were also measured to assess and correlate changes in melt properties due to peroxide modification. Melt strength and zero shear viscosity of both recycled and virgin material were enhanced with the increase in composition of peroxide. However, addition of peroxide also brought with it flow instabilities like draw resonance and necking, both of which lead to limitations in polymer processing. DOI : 10.3139/217.2126 En ligne : https://drive.google.com/file/d/1_RgAUGCEC4-zY90Xfu-EqUNcPFOCdRVe/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2649
in INTERNATIONAL POLYMER PROCESSING > Vol. XXIII, N° 2 (05/2008) . - p. 200-207[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 010098 - Périodique Bibliothèque principale Documentaires Disponible
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
IsotropieL'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
ViscositéIndex. 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 parametersDOI : 10.3139/217.2756 En ligne : https://drive.google.com/file/d/1JPVbfInsdDpifQus6Xojow_aMgICSbZE/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=19893
in INTERNATIONAL POLYMER PROCESSING > Vol. XXVIII, N° 5 (11/2013) . - p. 470-482[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 15682 - Périodique Bibliothèque principale Documentaires Disponible
