02670nas a2200229   4500008004100000022001400041245015400055210006900209260007300278300001200351490000800363520176700371653002302138653003402161653001902195653001602214100001802230700002102248700002102269700002702290856012302317       2007                        eng d  a0377-025700aSimulation of viscoelastic flows of polymer solutions in abrupt contractions using an arbitrary lagrangian eulerian (ALE) based finite element method0 aSimulation of viscoelastic flows of polymer solutions in abrupt   aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAY  a157-1690 v1433 a<p>We present a method for simulation of viscoelastic flows using an Arbitrary Lagrangian Eulerian (ALE) technique based finite element formulation. The ALE technique provides advantages of both Lagrangian and Eulerian frameworks by allowing the computational mesh to move in an arbitrary manner, independent of the material motion. In the present method, a fractional step ALE technique is employed in which the Lagrangian phase of material motion and convection arising out of mesh motion are decoupled. In the first step the relevant flow and constitutive equations are solved in Lagrangian framework. The simpler representation of polymer constitutive equations in a Lagrangian framework avoids the difficulties associated with convective terms thereby resulting in a robust numerical formulation. In the second step the mesh is moved in ALE mode and the associated convection of the stress is performed using a Godunov type scheme. This ALE technique is easy to implement and can accurately simulate the complex viscoelastic behaviour of transient polymer flow through complex geometries. In the present study, steady flows through abrupt contractions of planar and axisymmetric geometries are studied by performing transient flow simulations until steady state is achieved. The proposed method is validated with previously published numerical and experimental studies for polymer solutions obeying the Oldroyd B and Phan Thien Tanner (PTT) models. The simulated corner and lip vortex enhancement mechanism and flow behavior are in good agreement with experimentally obtained flow visualization photographs. The strength of the proposed method lies in its ability to simulate free surface flows such as swell. (C) 2007 Elsevier B.V. All rights reserved.</p>10aabrupt contraction10aArbitrary Lagrangian Eulerian10afinite element10asimulations1 aGanvir, Vivek1 aLele, Ashish, K.1 aThaokar, Rochish1 aGautham, Basavarsu, P.  uhttps://library.ncl.res.in/content/simulation-viscoelastic-flows-polymer-solutions-abrupt-contractions-using-arbitrary02508nas a2200253   4500008004100000022001400041245012300055210006900178260000800247300001100255490000700266520164100273653002201914653002601936653002101962653002601983653001302009653001602022100001902038700001802057700002402075700003102099856012402130       2023                        eng d  a0969-023900aSynthesis of N-oxyethylene substituted imidazolium-based zwitterions as a recyclable solvent for cellulose dissolution0 aSynthesis of Noxyethylene substituted imidazoliumbased zwitterio  cJAN  a87-1090 v303 a<p>
	Cellulose is a readily available, renewable, and natural biomaterial that has the potential to replace synthetic fibres. However, their processing to shaped materials such as fibre or film is still complex and restricted due to its insolubility in most conventional solvents. Herein, we present the synthesis and cellulose dissolution characteristics of a new class of recyclable zwitterions composed of tethered N-oxyethylene substituted imidazolium cation and alkyl carboxylate anion. Investigations on cellulose dissolution showed that increasing the alkyl chain length of carboxylate anion and introduction of oxyethylene unit on imidazolium ring led to better cellulose dissolution ability, and up to 12% (w/w) cellulose could be dissolved in aqueous zwitterions at 105 degrees C. The thermal behavior of zwitterions and their cellulose solutions was characterized by TGA and found to be more stable than the NMMO and Lyocell solutions. Rheological characterization of cellulose solutions revealed viscoelastic behavior and zero shear viscosity of 6-12% (w/w) cellulose solution in hexanoate containing aqueous zwitterion was 555 to 5900 Pa.s at 120 degrees C. The characteristics of cellulose solution indicate its potential for processing to cellulose fibre by extrusion through a tiny spinneret. Physico-chemical analysis of regenerated cellulose indicates that zwitterions cause no adverse effect on cellulose structure and morphology during dissolution. The zwitterions are recovered after the cellulose regeneration process, and the recovery was found to be 99.6% after purification using the ion-exchange method.</p>
10aCarboxylate anion10aCellulose dissolution10aOxyethylene unit10aRegenerated cellulose10aRheology10azwitterions1 aJadhav, Sachin1 aGanvir, Vivek1 aSingh, Madan, Kumar1 aShanmuganathan, Kadhiravan  uhttps://library.ncl.res.in/content/synthesis-n-oxyethylene-substituted-imidazolium-based-zwitterions-recyclable-solvent00811nas a2200217   4500008004100000022001400041245012800055210006900183260000900252490000800261653001400269653002300283653002400306100001900330700002100349700001900370700001800389700002400407700003100431856013100462       2025                        eng d  a0144-861700aStructure and properties of the cellulose fibres spun from imidazolium-based carboxylate functionalized zwitterionic liquid0 aStructure and properties of the cellulose fibres spun from imida  cJAN 0 v34810acellulose10aDirect dissolution10aZwitterionic liquid1 aJadhav, Sachin1 aSingh, Dhirendra1 aGupta, Deepika1 aGanvir, Vivek1 aSingh, Madan, Kumar1 aShanmuganathan, Kadhiravan  uhttps://library.ncl.res.in/content/structure-and-properties-cellulose-fibres-spun-imidazolium-based-carboxylate-functionalized