02940nas a2200313   4500008004100000022001400041245010600055210006900161260007300230300001000303490000800313520191500321653001202236653002002248653002302268653002402291653000802315653000802323653000802331100001802339700002702357700002302384700001702407700001702424700002102441700002102462700002102483856012202504       2011                        eng d  a0377-025700aExtrudate swell of linear and branched polyethylenes: ALE simulations and comparison with experiments0 aExtrudate swell of linear and branched polyethylenes ALE simulat  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJAN  a12-240 v1663 a<p>Extrudate swell is a common phenomenon observed in the polymer extrusion industry. Accurate prediction of the dimensions of an extrudate is important for appropriate design of dies for profile extrusion applications. Prediction of extrudate swell has been challenging due to (i) difficulties associated with accurate representation of the constitutive behavior of polymer melts, and (ii) difficulties associated with the simulation of free surfaces, which requires special techniques in the traditionally used Eulerian framework. In a previous work we had argued that an Arbitrary Lagrangian Eulerian (ALE) based finite element formulation may have advantages in simulating free surface deformations such as in extrudate swell. In the present work we reinforce this argument by comparing our ALE simulations with experimental data on the extrudate swell of commercial grades of linear polyethylene (LLDPE) and branched polyethylene (LOPE). Rheological behavior of the polymers was characterized in shear and uniaxial extensional deformations, and the data was modeled using either the Phan-Thien Tanner (PTT) model or the eXtended Pom-Pom (XPP) model. Additionally, flow birefringence and pressure drop measurements were done using a 10:1 contraction-expansion (CE) slit geometry in a MultiPass Rheometer. Simulated pressure drop and contours of the principal stress difference were compared with experimental data and were found to match well. This provided an independent test for the accuracy of the ALE code and the constitutive equations for simulating a processing-like flow. The polymers were extruded from long (L/D=30) and short (L/D=10) capillaries dies at 190 degrees C. ALE simulations were performed for the same extrusion conditions and the simulated extrudate swell showed good agreement with the experimental data. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.</p>10aALE-FEM10aextrudate swell10aFlow birefringence10aMultiPass Rheometer10aPSD10aPTT10aXPP1 aGanvir, Vivek1 aGautham, Basavarsu, P.1 aPol, Harshawardhan1 aBhamla, Saad1 aSclesi, Lino1 aThaokar, Rochish1 aLele, Ashish, K.1 aMackley, Malcolm  uhttps://library.ncl.res.in/content/extrudate-swell-linear-and-branched-polyethylenes-ale-simulations-and-comparison-001807nas a2200241   4500008004100000022001400041245012000055210006900175260007900244300001200323490000700335520092300342653001201265653002001277653002901297653000801326100001801334700002701352700002101379700002101400700002201421856012201443       2011                        eng d  a0334-644700aNumerical and experimental studies on extrudate swell of branched polyethylene through axisymmetric and planar dies0 aNumerical and experimental studies on extrudate swell of branche  aGENTHINER STRASSE 13, D-10785 BERLIN, GERMANYbWALTER DE GRUYTER & COcJUL  a217-2210 v313 a<p>Extrudate swell is simulated using an Arbitrary Lagrangian Eulerian (ALE) technique based finite element formulation and the same has been validated by comparing the results with reported numerical and experimental studies. In the present work we compare our ALE simulations with our own experimental data on the extrudate swell of commercial grade low density polyethylene (LDPE) resin. The resins were characterized for their rheological behavior in both shear and uniaxial extension. The polymers were extruded from a capillary under isothermal conditions and the extrudates were observed on-line using a video camera. ALE simulations were performed using molecular constitutive model like eXtended Pom-Pom (XPP) for branched (LDPE). The simulated extrudate swell was a good match with the experimental data. It was found that the swell values of LPDE through planar die are higher than the axisymmetric die.</p>10aALE-FEM10aextrudate swell10apolymer flow simulations10aXPP1 aGanvir, Vivek1 aGautham, Basavarsu, P.1 aThaokar, Rochish1 aLele, Ashish, K.1 aPol, Harshwardhan  uhttps://library.ncl.res.in/content/numerical-and-experimental-studies-extrudate-swell-branched-polyethylene-through-0