Rheologica Acta

, Volume 48, Issue 6, pp 611–624

Droplet formation in quickly stretched liquid filaments

Original Contribution

Abstract

Film splitting necessarily occurs in roll coating and unwanted droplets can occur at high machine speeds when the resulting filaments break up. To study this ‘misting’ problem, an apparatus was designed and built to simulate filament fluid mechanics. The device creates a filament by elongating a liquid bridge and stretches the filament at a high and constant rate of acceleration to mimic coating machine kinematics. Filament breakup was observed using a high-speed video camera and the images were analyzed to yield droplet size and number. With Newtonian fluids, a single droplet formed at Ohnesorge (Oh) numbers less than 0.1 and more and smaller droplets were produced at Oh numbers above 0.1. Associative polymer solutions, prepared as weakly elastic fluids to represent industrial coatings, produced even more and smaller droplets, but only for Ohnesorge numbers in the range of 0.01 to 0.1.

Keywords

Filament breakup Quick stretching Misting Droplets Elasticity Uniaxial extension 

References

  1. Anna SL, McKinley GH (2001) Elastocapillary thinning and breakup of model elastic liquids. J Rheol 45:115–138CrossRefADSGoogle Scholar
  2. Anna SL, McKinley GH, Nguyen DA, Sridhar T, Muller SJ, Huang J, James DF (2001) An inter-laboratory comparison of measurements from filament-stretching rheometers using common test fluids. J Rheol 45:83–114CrossRefADSGoogle Scholar
  3. Ascanio G, Carreau PJ, Reglat O, Tanguy PA (2005) Extensional rheology of coating suspensions in relation with misting in film coaters. J Nordic Pulp Pap Res 20:48–52CrossRefGoogle Scholar
  4. Ercan SN, Bousfield DW (2001) Influence of fluid rheology on filament size. In: Int printing & graphic arts conference procGoogle Scholar
  5. Fernando RH, Xing L-L, Glass JE (2001) Erratum to “Rheology parameters controlling spray atomization and roll misting behavior of waterborne”. Prog Org Coat 42:284–288CrossRefGoogle Scholar
  6. Gron J (2000) Development of metered size press coating for high-speed operations. In: TAPPI metered size press symposium proc, p 241Google Scholar
  7. Howard PR, Leasure EL, Rosier ST, Schaller EJ (1991) System approach to rheology control. In: Glass EJ (ed) Polymers as rheology modifiers, vol 462. ACS symposium, p 207Google Scholar
  8. James DF, Yogachandran N (2006) Filament breaking length—a measure of elasticity in extension. Rheol Acta 46:161–170CrossRefGoogle Scholar
  9. James DF, Yogachandran N, Roper JA III (2003) Fluid elasticity measured by a new technique correlates with misting. In: TAPPI 8th advanced coating fundamentals symposiumGoogle Scholar
  10. Mannheimer R (1983) Rheological and mist ignition properties of dilute polymer solutions. Chem Eng Commun 19:221–341CrossRefGoogle Scholar
  11. Marmottant P, Villermaux E (2004) Fragmentation of stretched liquid ligaments. Phys Fluids 16:2732–2741CrossRefADSGoogle Scholar
  12. Notz PK, Chen AU, Basaran OA (2001) Satellite drops: unexpected dynamics and change of scaling during pinch-off. Phys Fluids 13:549–552CrossRefADSGoogle Scholar
  13. Pouran M (2006) Droplet formation and rheology in roll coating. PhD thesis, Dept Mech and Ind Eng, University of TorontoGoogle Scholar
  14. Roper JA III, Urscheler R, Bousfield DW, Salminen P (1997) Observations and proposed mechanism of misting on high-speed metered size press coaters. In: TAPPI coating conference proc, pp 1–14Google Scholar
  15. Sadeghy K, James DF (2000) Elasticity of associative polymer solutions and slip at high shear stress. J Non-Newton Fluid Mech 90:127–158MATHCrossRefGoogle Scholar
  16. Salminen PJ, Roper JA III, Urscheler R, Chase D (1996) Optimizing the coating formulation to reduce misting in high-speed coating. In: TAPPI metered size press forum, pp 51–55Google Scholar
  17. Smolinski JM, Gulari E, Manke CW (1996) Atomization of dilute polyisobutylene mineral oil solutions. AICHE J 42:1201–1212CrossRefGoogle Scholar
  18. Tirtaatmadja V, Sridhar T (1993) A filament stretching device for measurement of extensional viscosity. J Rheol 37:1081–1102CrossRefADSGoogle Scholar
  19. Zhang X, Padgett RS, Basaran OA (1996) Nonlinear deformation and breakup of stretching liquid bridges. J Fluid Mech 329:207–245MATHCrossRefADSGoogle Scholar

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  1. 1.Department of Mechanical and Industrial EngineeringUniversity of TorontoTorontoCanada
  2. 2.Fluor Enterprises Inc.Sugar LandUSA

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