Excess pressure losses in the capillary flow of molten polymers

✍ Scribed by Savvas G. Hatzikiriakos; Evan Mitsoulis

• Publisher: Springer-Verlag
• Year: 1996
• Tongue: English
• Weight: 936 KB
• Volume: 35
• Category: Article
• ISSN: 0035-4511
• DOI: 10.1007/bf00396506

✦ Synopsis

The excess pressure losses due to end effects in the capillary flow of a linear low-density polyethylene resin (LLDPE) were studied both experimentally and numerically. First, they were determined experimentally by using two methods: i) by extrapolating experimental data of pressure drop versus length-to-radius ratios (L/R) to zero capillary length and ii) by means of using orifice dies (L/R = 0). Both methods resulted in about the same end corrections. Numerical simulation was also used to model this important aspect of experimental rheology. The con-stitutive equation used in the simulations is a multimode K-BKZ equation proposed by Papanastasiou et al. (1983, J. Rheol. 27:387) and further modified by Luo and Tanner (1988, Int. J. Num. Meth. Eng., 25:9). It was found that the numerical predictions agreed qualitatively, but underestimated the experimental data for the various geometries used to determine the end effects.