Swell and distortions of high-density polyethylene extruded through capillary dies Export

@article{citeulike:3518037, abstract = {The effect of varying the die entrance angle and the die length on extrudate swell and on the onset of extrudate distortion in capillary extrusion has been studied. Using theory from the literature, we have analyzed the contribution to the total pressure drop from the elongational and shear deformation in the entrance region, and from the capillary pressure drop in the land region of the die. From the contribution of the elongational deformation, we obtained an estimate for the elongational viscosity of the polymer. The same analysis was used to study the influence of the die geometry on the stick-slip instability. It is found that the elongational component at the inlet region mainly influences the extrudate distortions. The onset of the stick-slip instability occurs within 10\% at a wall stress tauw of 0.3MPa, where tauw is calculated from expressions assuming fully developed flow. The variation around this average value is systematic with changes in die geometry, and the observed variations are probably due to the non-homogeneous pressure field in the die. We also propose a model for predicting extrudate swell. Input to the model are material parameters obtainable from oscillatoric measurements of the loss and storage modulus and residence times calculated from the geometry of the die. The swell model includes a fitting parameter that sets the overall scale of the swell.}, address = {Borealis A/S N-3960 Stathelle, Norway; SINTEF N-0314 Oslo, Norway}, author = {Eggen, Svein and Hinrichsen, Einar L.}, citeulike-article-id = {3518037}, citeulike-linkout-0 = {http://dx.doi.org/10.1002/pen.10428}, citeulike-linkout-1 = {http://www3.interscience.wiley.com/cgi-bin/abstract/108064276/ABSTRACT}, doi = {10.1002/pen.10428}, journal = {Polymer Engineering \& Science}, keywords = {1996, hdpe, lab3, viscoelastic}, number = {3}, pages = {410--424}, posted-at = {2008-11-15 05:03:06}, priority = {2}, title = {Swell and distortions of high-density polyethylene extruded through capillary dies}, url = {http://dx.doi.org/10.1002/pen.10428}, volume = {36}, year = {1996} }

TY - JOUR ID - citeulike:3518037 L3 - citeulike-article-id:3518037 N2 - The effect of varying the die entrance angle and the die length on extrudate swell and on the onset of extrudate distortion in capillary extrusion has been studied. Using theory from the literature, we have analyzed the contribution to the total pressure drop from the elongational and shear deformation in the entrance region, and from the capillary pressure drop in the land region of the die. From the contribution of the elongational deformation, we obtained an estimate for the elongational viscosity of the polymer. The same analysis was used to study the influence of the die geometry on the stick-slip instability. It is found that the elongational component at the inlet region mainly influences the extrudate distortions. The onset of the stick-slip instability occurs within 10% at a wall stress tauw of 0.3MPa, where tauw is calculated from expressions assuming fully developed flow. The variation around this average value is systematic with changes in die geometry, and the observed variations are probably due to the non-homogeneous pressure field in the die. We also propose a model for predicting extrudate swell. Input to the model are material parameters obtainable from oscillatoric measurements of the loss and storage modulus and residence times calculated from the geometry of the die. The swell model includes a fitting parameter that sets the overall scale of the swell. IS - 3 JF - Polymer Engineering & Science AD - Borealis A/S N-3960 Stathelle, Norway; SINTEF N-0314 Oslo, Norway EP - 424 TI - Swell and distortions of high-density polyethylene extruded through capillary dies VL - 36 SP - 410 KW - 1996 KW - hdpe KW - lab3 KW - viscoelastic AU - Eggen, Svein AU - Hinrichsen, Einar PY - 1996/// UR - http://dx.doi.org/10.1002/pen.10428 ER -