The influence of the extensional viscosity of very low concentrations of high molecular mass water‐soluble polymers on atomisation and droplet impact

Williams, Peter A.; English, Robert J.; Blanchard, Rowan L; Rose, Simon A. H.; Lyons, Lynn; Whitehead, M. E.

doi:10.1002/ps.1523

Cited by 22 publications

(16 citation statements)

References 32 publications

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“…Controlling droplet deposition is of tremendous commercial interest. The ecological and economic benefits to the agrochemical industry in limiting wasted pesticides are enormous [2], but inkjet printing and many spray applications, including spray cooling, also require careful control of the droplet impact [3], making suppression of droplet rebound an important industrial problem.…”

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confidence: 99%

Effect of Polymer Additives on the Wetting of Impacting Droplets

2010

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When a droplet of water impacts a hydrophobic surface, the drop is often observed to bounce. However, for about 10 years it has been known that the addition of very small quantities (approximately 100 ppm) of a flexible polymer such as poly-(ethylene oxide) can completely prevent rebound. This effect has for some time been explained in terms of the stretching of polymer chains by a velocity gradient in the fluid, resulting in a transient increase in the so-called "extensional viscosity." Here we show, by measuring the fluid velocity inside the impacting drop, that the extensional viscosity plays no role in the antirebound phenomenon. Using fluorescently labeled lambda DNA we demonstrate that the observed effect is due to the stretching of polymer molecules as the droplet edge sweeps the substrate, retarding the movement of the receding contact line.

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confidence: 99%

Effect of Polymer Additives on the Wetting of Impacting Droplets

2010

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“…Fernando et al (2000) showed that roll misting can be prevented using fluids with low extensional viscosity. The tendency of the droplet bounce after impact is decreased by an increase in the extensional viscosity (Bergeron et al 2000;Williams et al 2008). Furthermore, elongational flow resistance supports the decrease in fluid retraction (Bergeron et al 2000; Bartolo et al 2007).…”

Section: Introductionmentioning

confidence: 72%

Controlling the elongational flow behavior of complex shear-thinning fluids without affecting shear viscosity

Oswald

Willenbacher

2019

Rheol Acta

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Complex flow fields including high elongational deformation occur in numerous industrial processes such as spraying, coating, fiber spinning, and screen or inkjet printing. Fully exploiting the potential of these technologies suffers from a lack of knowledge regarding how elongational flow properties of the processed fluids affect the results of these operations. Here, we present two strategies that allow for varying the elongational flow behavior independent of shear rheology. First, two acrylic thickener solutions that differ with respect to the fraction of hydrophobic co-monomers and hence with respect to their degree of interand intramolecular hydrophobic association were mixed to vary the elongational relaxation time, as determined using capillary breakup elongational rheometry (CaBER), by almost two orders of magnitude without affecting shear viscosity of these solutions in a wide, processing-relevant shear rate range. Second, a substantial increase in the elongational flow resistance was achieved by adding a small amount of plate-like particles without affecting the shear viscosity of these thickener solutions. A fourfold increase of the elongational relaxation time was observed upon the addition of 3.5 vol.% of glass flakes to such a highly shear-thinning system. A similar effect was also observed for an industrial waterborne automotive basecoat due to added aluminum flakes. This work may be useful for product development since the control of extensional viscosity can improve technological applications, and the introduced model systems may therefore be used for systematic, goal-oriented investigations of the relevance of elongational flow properties in the technological processes mentioned above.

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“…10). A Taylor cone is created by the electrostatic force of attraction, but due to the low elongational viscosity [56][57][58] of the polymer solution, a jet of droplet is released. The high surface areato-volume ratio leads to evaporation of solvents.…”

Section: Discussionmentioning

confidence: 99%

Electrospinning of Matrigel to Deposit a Basal Lamina-Like Nanofiber Surface

Guzman¹,

Loeb²,

VandeVord³

2010

j biomater sci polym ed

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Schwann cell basal lamina is a nanometer-thin extracellular matrix layer that separates the axon-bound Schwann cells from the endoneurium of the peripheral nerve. It is implicated in the promotion of nerve regeneration after transection injury by allowing Schwann cell colonization and axonal guidance. Hence, it is desired to mimic the native basal lamina for neural tissue engineering applications. In this study, basal lamina proteins from BD Matrigel (growth factor-reduced) were extracted and electrospun to deposit nonwoven nanofiber mats. Adjustment of solute protein concentration, potential difference, air gap distance and flow rate produced a basal lamina-like construct with an average surface roughness of 23 nm and composed of 100-nm-thick irregular and relatively discontinuous fibers. Culture of embryonic chick dorsal root ganglion explants demonstrated that the fabricated nanofiber layer supported explant attachment, elongation of neurites, and migration of satellite Schwann cells in a similar fashion compared to electrospun collagen type-I fibers. Furthermore, the presence of nanorough surface features significantly increased the neurite spreading and Schwann cell growth. Sciatic nerve segment incubation also showed that the construct is promigratory to nerve Schwann cells. Results, therefore, suggest that the synthetic basal lamina fibers can be utilized as a biomaterial for induction of peripheral nerve repair.

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The influence of the extensional viscosity of very low concentrations of high molecular mass water‐soluble polymers on atomisation and droplet impact

Cited by 22 publications

References 32 publications

Effect of Polymer Additives on the Wetting of Impacting Droplets

Effect of Polymer Additives on the Wetting of Impacting Droplets

Controlling the elongational flow behavior of complex shear-thinning fluids without affecting shear viscosity

Electrospinning of Matrigel to Deposit a Basal Lamina-Like Nanofiber Surface

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