Abstract
Measurements on seven rigid PVC compounds were carried out with a slit rheometer working in combination with an injection moulding machine. Plastication of the compounds occurred in the screw of the plastication unit, which also forced the melt through the die with a controlled forward velocity. The rectangular slit had a length of 90 mm and a widthB of 20 mm. The heightH could be varied between 0.8 and 3.3 mm. Pressures and temperatures were recorded at several positions in and before the die. Measurements were carried out at shear rates from 10 to 2000 s−1.
When the reduced volume output\(\dot V_{red} = \dot V/BH^2 \) was plotted against the wall shear stressτ W , only four compounds showed master curves independent ofH, which is indicative of wall adhesion. In the other cases this plot did not produce such a master curve, but the plot of the mean velocity\(\dot V/BH\) againstτ W was independent ofH (slip curve). This indicated that slip flow prevailed with a slip velocityv G ≈\(v_G \approx \dot V/BH\)
When, in the case of wall slip, the smooth inner surfaces of the die were replaced by surfaces with grooves perpendicular to the direction of flow, slip flow was prevented and the flow curves\(\dot V = f(\Delta p)\) were shifted to much higher values of τ Wc Above a critical value of the wall shear stress (τ Wc ) at which slip flow began, the output became nearly independent ofτ W . From the measurements made belowτ Wc a τ vs.\(\dot \gamma \) relation for the shear flow could be derived, which was used to calculate the superimposed shear flow\(\dot V_S = f(\tau _W )\). Exact values of the slip velocity were then given by\(v_G = (\dot V - \dot V_S )/BH\). Wall slip only occurred for compounds with a high shear viscosity, which corresponds to a high molecular weight (K-value).
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
References
Collins EA, Fahey TE, Hopfinger AJ (1982) Organic Coatings and Applied Polymer Science Proceedings 46:368–373
Collins EA (1977) Pure Appl Chem 49:581–595
Cernoch J, Stihel Z, Tluchor J (1980) Plaste u. Kautschuk 27:621–623; 28:200–202, 270–272
Berger R (1972) Plaste u. Kautschuk 19:113–118
Uhland E (1979) Rheol Acta 18:1–24
Offermann H (1972) Die Rheometrie wandgleitender Kunststoffschmelzen, untersucht am Beispiel von Hart-PVC. Dissertation TH Aachen
Chauffoureaux JC, Dehennau C, van Rijckevorsel J (1979) J Rheology 23:1–24
Funatsu K, Sato M (1984) Proceedings IX. Intl. Congress on Rheology. Mexico, vol 4 Applications, pp 465–472
Knappe W, Krumböck E (1984) Proceedings IX. Intl. Congress on Rheology. Mexico, vol 3 Polymers, pp 417–424
van Leuwen J (1967) Polym Eng Sci 7:1–12
Krumböck E (1984) Zum Wandgleiten von PVC-hart Mischungen im fließfähigen Zustand. Dissertation Montanuniversität Leoben
Görmar H (1968) Beitrag zur verarbeitungstechnischen Dimensionierung von Breitschlitzwerkzeugen für thermisch instabile Thermoplaste, insbesondere PVC-hart. Dissertation TH Aachen
Tse M (1981) Polym Eng Sci 21:1037–1045
Kuhn B (1977) Rheometrische Untersuchungen am System Polyvinylchlorid-Weichmacher. VDI-Verlag, Düsseldorf, Fortschritt-Berichte, Reihe 5, Nr 33
Eswaran R, Janeschitz-Kriegl H, Schijf J (1963) Rheol Acta 3:83–91
Wales JLS (1975) J Polym Sci, Symposium No 50:469–485
Anonym: Kurzinformation: Methylenchlorid-Test. Deutsche Solvay-Werke GmbH, Solvic Kurzinformation 59, Ausg 1/73
den Otter JL, Schijf J, Wales JLS, Schwarzl FR (1974) Rheol Acta 13:209–215
Mooney M (1931) J Rheology 2:210–222
Janssen LPBM (1980) Rheol Acta 18:32–37
Author information
Authors and Affiliations
Additional information
Dedicated to Professor H. Janeschitz-Kriegl on the occasion of his 60th birthday.
Rights and permissions
About this article
Cite this article
Knappe, W., Krumböck, E. Slip flow of non-plasticized PVC compounds. Rheol Acta 25, 296–307 (1986). https://doi.org/10.1007/BF01357956
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF01357956