Abstract
Polymer degradation is readily observed in flows where the extensional component surpasses the rotational component of the velocity gradient. This type of flow is conveniently obtained by pushing a liquid into a convergent channel across an orifice. Kinetics of chain scission is sensitive to subtle modification of the coil conformation, which in turn depends on the details of the pervading flow field. By changing the orifice diameter and the conical angle of the inlet, it is possible to modify the spatial distribution of the velocity gradient, and hence, the residence time of a fluid element in the high strain-rate region. Degradation yields, measured under π-conditions in decalin by Gel Permeation Chromatography, showed a strong dependence on the fluid velocity at the orifice, but not on the magnitude of the strain-rate. This result is contrary to the common belief that assumes viscous friction, proportional to the strain-rate, is the determining factor for the scission rate of a bond under stress. Rather, experimental findings tend to indicate that the driving force for chain scission was provided by the energy accumulated in the coil during the flow-induced deformation process. The sharp propensity for mid-chain scission was maintained regardless of the nozzle geometry.
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
Keller A, Mackley MR (1974) Pure Appl Chem 39:195
Smith KA, Merrill EW, Peebles LH, Banijamali SH (1975) Polymères et Lubrification, Colloques Intern du CNRS, Paris 233:341
Akay G (1982) Polym Eng Sci 22:798
Jhon MS, Sekhon G, Armstrong RC (1987) Adv Chem Phys 66:153
Merrill EW, Leopairat P (1980) Polym Eng Sci 20:505
Nguyen QT, Kausch HH (1986) Colloid Polym Sci 264:764
Pope DP, Keller A (1978) Colloid Polym Sci 256:751
Nguyen H, Boger DV (1979) J Non-Newt Fluid Mech 5:353
Viriyayuthakorn M, Caswell B (1980) J Non-Newt Fluid Mech 6:245
Ryskin G (1987) J Fluid Mech 178:423
Gatski TB, Lumley JL (1978) J Fluid Mech 86:623
Crater DH, Cuculo JA (1983) J Polym Sci Polym Phys Ed 21:2219
Nguyen QT, Kausch HH (1988) J Non-Newt Fluid Mech 30:125
Nguyen QT, Kausch HH (1990) results to be published
Kausch HH (1987) Polymer fracture, 2nd Ed. Springer Verlag, Berlin-Heidenberg, p 129
Leal LG (1985) In: Rabin Y (ed) Polymer-flow interaction. American Institute of Physics, New York, p 5
De Gennes PG (1974) J Chem Phys 60:5030
Zimm BH (1956) J Chem Phys 24:269
Layec-Raphalen MN, Wolff C (1976) J Non-Newt Fluid Mech 5:463
Nicolai T, Brown W, Johnsen R (1989) Macromolecules 22:2795
Nguyen QT, Kausch HH (1990) Macromolecules 23:5137
Giesekus H (1962) Rheol Acta 2:122
Nguyen QT, Kausch HH (1989) Makromol Chem 190:1389
Polyflow SA, Polyflow, a finite element program for calculating viscous and viscoelastic flows. Polyflow SA, Louvain-la-Neuve, Belgium
Bird RB, Armstrong RC, Hassager O (1987) Dynamics of polymeric liquids, 2nd Ed. John Wiley Sons, New York, Toronto, 1:82
Zhurkov SN, Korsukov VE (1974) J Polym Sci Polym Phys Ed 12:385
Boudreaux DS (1973) J Polym Sci Polym Phys Ed 11:1285
Tanner RI (1988) Engineering rheology, Rev. Ed. Clarendon Press, Oxford, p 329
Kuhn W, Kuhn H (1946) 29:609
Cerf R (1957) J Polym Sci 23:125
De Gennes PG (1977) J Chem Phys 66:5825
Bird RB, Armstrong RC, Hassager O (1987) Dynamics of polymeric liquids, 2nd Ed. John Wiley Sons, New York, Toronto 2:105
Bestul AB (1956) J Chem Phys 24:1196
Ballauff M, Wolf BA (1988) Adv Pol Sci 85:1
Wolf BA (1987) Makromol Chem Rapid Comm 8:461
Odell JA (1990) private communication
Keller A, Odell JA (1985) Colloid Polym Sci 263:181
Author information
Authors and Affiliations
Additional information
Dedicated to Prof. W. R. Pechhold on the occasion of his 60th birthday
Rights and permissions
About this article
Cite this article
Nguyen, T.Q., Kausch, H.H. Influence of nozzle geometry on polystyrene degradation in convergent flow. Colloid Polym Sci 269, 1099–1110 (1991). https://doi.org/10.1007/BF00654117
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00654117