Laser-Doppler velocimetry - a powerful tool to investigate the flow behavior of polymer melts

• Autorzy: Merten A. , Schwetz M. , Münstedt H.
• Konferencja: Second International Conference on Engineering Rheology ICER 2003
• Języki publikacji: EN

Abstrakty

EN

The flow behavior of a low density polyethylene (LDPE) and a high density polyethylene (HDPE) melt in the entrance region, the interior of slit, and within a slit die was investigated by means of laser-Doppler velocimetry (LDV). Large vortices were found upstream of the die with for the LDPE. The HDPE did not exhibit any vortices. The velocities within the vortices are about 100 times smaller than those in the center of the flow. Far-reaching consequences for processing arise as the residence time of the melt in the vortices is long. The velocity distribution along the channel axis reveals large elongational deformations near the contraction. The elongational velocities are much higher than those attainable by elongational rheometers. For the HDPE it could be shown that the material slips at the wall.

Słowa kluczowe

EN

laser Doppler velocimetry; polyethylene melts; slit die; secondary flow; wall slip

PL

polimery; poślizg; polietylen

• Wydawca: Oficyna Wydawnicza Uniwersytetu Zielonogórskiego
• Czasopismo: International Journal of Applied Mechanics and Engineering
• Rocznik: 2003
• Tom: Vol. 8, no spec.
• Strony: 283--288
• Opis fizyczny: Bibliogr. 6 poz., rys., wykr.

Twórcy

autor

Merten A.

• Institute of Polymer Materials, University Erlangen-Nürnberg, D-91058 Erlangen, GERMANY

autor

Schwetz M.

• Institute of Polymer Materials, University Erlangen-Nürnberg, D-91058 Erlangen, GERMANY

autor

Münstedt H.

• Institute of Polymer Materials, University Erlangen-Nürnberg, D-91058 Erlangen, GERMANY

Bibliografia

• [1] Ahmed R. and Mackley M.R. (1995): Experimental centreline planar extension of polyethylene melt flowing into a sllt die. - Journal of Non-Newtonian Fluid Mechanics, vol.56, pp.127-149.
• [2] Bagley E.B. and Birks A.M. (1960): Flow of polyethylene into a capillary. - Journal of Applied Physics, Laser Doppler-Anemometrie bei der Extrusion von Polyethylenschmelzen, vol.31, No.3, pp.556-561.
• [3] Durst F., Melling A. and Whitelaw J.H. (1981): Principles and Practice of Laser-Doppler Anemometry. - Aćademlu Press, 2nd Edition.
• [4] Kramer H. and Meissner J. (1980): Application of the laser-Doppler-anemometry to polymer melt flow studies, Proceedings of the 8th International Congress on Rheology, Naples, September, 1980, vol.2: Fluids, pp.463-468.
• [5] Mackley M.R. and Moore I.P.T. (1986): Experimental velocity distribution measurements of high density polyethylene flowing into and within a slit. - Journal of Non-Newtonian Fluid Mechanics, vol.21, pp.337-358.
• [6] Wassner E. (1998): Stromungsuntersuchungen mit der Laser-Doppler-Anemometrie bei der Extrusion UOH Polyethylenschmelzen. - Dissertation, Universitat Erlangen-Niirnberg.