The Experts below are selected from a list of 15 Experts worldwide ranked by ideXlab platform
Ashish Lele - One of the best experts on this subject based on the ideXlab platform.
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Nonisothermal analysis of extrusion film casting process using molecular constitutive equations
Rheologica Acta, 2014Co-Authors: Sourya Banik, Lal Busher Azad, Sumeet Thete, Pankaj Doshi, Ashish LeleAbstract:Extrusion film casting (EFC) is a commercially important process that is used to produce several thousand tons of Polymer films and coatings. In a recent work, we demonstrated the influence of Polymer chain architecture on the extent of necking in an isothermal film casting operation (Pol et al., J Rheol 57:559–583, 2013 ). In the present research, we have explored experimentally and theoretically the effects of Long-Chain branching on the extent of necking during nonisothermal film casting conditions. Polyethylenes of linear and Long-Chain Branched architectures were used for experimental studies. The EFC process was analyzed using the 1-D flow model of Silagy et al. (Polym Eng Sci 36:2614–2625, 1996 ) in which the energy equation was introduced to model nonisothermal effects, and two multimode constitutive equations, namely the “extended pom-pom” (XPP, for Long-Chain Branched Polymer melts) equation and the “Rolie-Poly stretch version” (RP-S, for linear Polymer melts) equation, were incorporated to account for the effects of Polymer chain architecture. We show that the model does a better job of capturing the qualitative features of the experimental data, thereby elucidating the role of chain architecture and nonisothermal conditions on the extent of necking.
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necking in extrusion film casting the role of macromolecular architecture
Journal of Rheology, 2013Co-Authors: Sumeet Thete, Pankaj Doshi, Ashish LeleAbstract:Extrusion film casting (EFC) is used on an industrial scale to produce several thousand tons of Polymer films and coatings. While significant research has been carried out on necking of films of viscoelastic melts in EFC, the influence of macromolecular chain architecture on the necking behavior is not yet fully understood. In the present research, we have explored experimentally and theoretically the effects of long chain branching and molecular weight distribution on the extent of necking during EFC. Polyethylenes of essentially linear architecture but having narrow and broad molecular weight distributions, and polyethylenes having long chain branching were used for experimental studies. The EFC process was analyzed using the one-dimensional flow model of Silagy et al. [Polym. Eng. Sci. 36(21), 2614–2625 (1996)] in which multimode molecular constitutive equations namely the “extended pom-pom” equation (for long chain Branched Polymer melts) and the “Rolie–Poly (Rouse linear entangled Polymers)” equation (for linear Polymer melts) were incorporated. We show that the model qualitatively captures the salient features of the experimental data thereby elucidating the role of chain architecture on the extent of necking.
Sumeet Thete - One of the best experts on this subject based on the ideXlab platform.
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Nonisothermal analysis of extrusion film casting process using molecular constitutive equations
Rheologica Acta, 2014Co-Authors: Sourya Banik, Lal Busher Azad, Sumeet Thete, Pankaj Doshi, Ashish LeleAbstract:Extrusion film casting (EFC) is a commercially important process that is used to produce several thousand tons of Polymer films and coatings. In a recent work, we demonstrated the influence of Polymer chain architecture on the extent of necking in an isothermal film casting operation (Pol et al., J Rheol 57:559–583, 2013 ). In the present research, we have explored experimentally and theoretically the effects of Long-Chain branching on the extent of necking during nonisothermal film casting conditions. Polyethylenes of linear and Long-Chain Branched architectures were used for experimental studies. The EFC process was analyzed using the 1-D flow model of Silagy et al. (Polym Eng Sci 36:2614–2625, 1996 ) in which the energy equation was introduced to model nonisothermal effects, and two multimode constitutive equations, namely the “extended pom-pom” (XPP, for Long-Chain Branched Polymer melts) equation and the “Rolie-Poly stretch version” (RP-S, for linear Polymer melts) equation, were incorporated to account for the effects of Polymer chain architecture. We show that the model does a better job of capturing the qualitative features of the experimental data, thereby elucidating the role of chain architecture and nonisothermal conditions on the extent of necking.
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necking in extrusion film casting the role of macromolecular architecture
Journal of Rheology, 2013Co-Authors: Sumeet Thete, Pankaj Doshi, Ashish LeleAbstract:Extrusion film casting (EFC) is used on an industrial scale to produce several thousand tons of Polymer films and coatings. While significant research has been carried out on necking of films of viscoelastic melts in EFC, the influence of macromolecular chain architecture on the necking behavior is not yet fully understood. In the present research, we have explored experimentally and theoretically the effects of long chain branching and molecular weight distribution on the extent of necking during EFC. Polyethylenes of essentially linear architecture but having narrow and broad molecular weight distributions, and polyethylenes having long chain branching were used for experimental studies. The EFC process was analyzed using the one-dimensional flow model of Silagy et al. [Polym. Eng. Sci. 36(21), 2614–2625 (1996)] in which multimode molecular constitutive equations namely the “extended pom-pom” equation (for long chain Branched Polymer melts) and the “Rolie–Poly (Rouse linear entangled Polymers)” equation (for linear Polymer melts) were incorporated. We show that the model qualitatively captures the salient features of the experimental data thereby elucidating the role of chain architecture on the extent of necking.
Pankaj Doshi - One of the best experts on this subject based on the ideXlab platform.
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Nonisothermal analysis of extrusion film casting process using molecular constitutive equations
Rheologica Acta, 2014Co-Authors: Sourya Banik, Lal Busher Azad, Sumeet Thete, Pankaj Doshi, Ashish LeleAbstract:Extrusion film casting (EFC) is a commercially important process that is used to produce several thousand tons of Polymer films and coatings. In a recent work, we demonstrated the influence of Polymer chain architecture on the extent of necking in an isothermal film casting operation (Pol et al., J Rheol 57:559–583, 2013 ). In the present research, we have explored experimentally and theoretically the effects of Long-Chain branching on the extent of necking during nonisothermal film casting conditions. Polyethylenes of linear and Long-Chain Branched architectures were used for experimental studies. The EFC process was analyzed using the 1-D flow model of Silagy et al. (Polym Eng Sci 36:2614–2625, 1996 ) in which the energy equation was introduced to model nonisothermal effects, and two multimode constitutive equations, namely the “extended pom-pom” (XPP, for Long-Chain Branched Polymer melts) equation and the “Rolie-Poly stretch version” (RP-S, for linear Polymer melts) equation, were incorporated to account for the effects of Polymer chain architecture. We show that the model does a better job of capturing the qualitative features of the experimental data, thereby elucidating the role of chain architecture and nonisothermal conditions on the extent of necking.
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necking in extrusion film casting the role of macromolecular architecture
Journal of Rheology, 2013Co-Authors: Sumeet Thete, Pankaj Doshi, Ashish LeleAbstract:Extrusion film casting (EFC) is used on an industrial scale to produce several thousand tons of Polymer films and coatings. While significant research has been carried out on necking of films of viscoelastic melts in EFC, the influence of macromolecular chain architecture on the necking behavior is not yet fully understood. In the present research, we have explored experimentally and theoretically the effects of long chain branching and molecular weight distribution on the extent of necking during EFC. Polyethylenes of essentially linear architecture but having narrow and broad molecular weight distributions, and polyethylenes having long chain branching were used for experimental studies. The EFC process was analyzed using the one-dimensional flow model of Silagy et al. [Polym. Eng. Sci. 36(21), 2614–2625 (1996)] in which multimode molecular constitutive equations namely the “extended pom-pom” equation (for long chain Branched Polymer melts) and the “Rolie–Poly (Rouse linear entangled Polymers)” equation (for linear Polymer melts) were incorporated. We show that the model qualitatively captures the salient features of the experimental data thereby elucidating the role of chain architecture on the extent of necking.
F Langouche - One of the best experts on this subject based on the ideXlab platform.
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the strain hardening behaviour of linear and long chain Branched polyolefin melts in extensional flows
Rheologica Acta, 2000Co-Authors: Manfred H Wagner, H Bastian, Peter Hachmann, Joachim Meissner, Stefan Kurzbeck, Helmut Munstedt, F LangoucheAbstract:By generalizing the Doi-Edwards model to the Molecular Stress Function theory of Wagner and Schaeffer, the extensional viscosities of polyolefin melts in uniaxial, equibiaxial and planar constant strain-rate experiments starting from the isotropic state can be described quantitatively. While the strain hardening of four linear Polymer melts (two high-density polyethylenes, a polystyrene and a polypropylene) can be accounted for by a tube diameter that decreases affinely with the average stretch, the two Long-Chain-Branched Polymer melts considered (a low-density polyethylene and a Long-Chain Branched polypropylene) show enhanced strain hardening in extensional flows due to the presence of Long-Chain branches. This can be quantified by a molecular stress function, the square of which is quadratic in the average stretch and which follows from the junction fluctuation theory of Flory. The ultimate magnitude of the strain-hardening effect is governed by a maximum value of the molecular stress, which is specific to the Polymer melt considered and which is the only free non-linear parameter of the theory.
Manfred H Wagner - One of the best experts on this subject based on the ideXlab platform.
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the strain hardening behaviour of linear and long chain Branched polyolefin melts in extensional flows
Rheologica Acta, 2000Co-Authors: Manfred H Wagner, H Bastian, Peter Hachmann, Joachim Meissner, Stefan Kurzbeck, Helmut Munstedt, F LangoucheAbstract:By generalizing the Doi-Edwards model to the Molecular Stress Function theory of Wagner and Schaeffer, the extensional viscosities of polyolefin melts in uniaxial, equibiaxial and planar constant strain-rate experiments starting from the isotropic state can be described quantitatively. While the strain hardening of four linear Polymer melts (two high-density polyethylenes, a polystyrene and a polypropylene) can be accounted for by a tube diameter that decreases affinely with the average stretch, the two Long-Chain-Branched Polymer melts considered (a low-density polyethylene and a Long-Chain Branched polypropylene) show enhanced strain hardening in extensional flows due to the presence of Long-Chain branches. This can be quantified by a molecular stress function, the square of which is quadratic in the average stretch and which follows from the junction fluctuation theory of Flory. The ultimate magnitude of the strain-hardening effect is governed by a maximum value of the molecular stress, which is specific to the Polymer melt considered and which is the only free non-linear parameter of the theory.
