Thinning of drying latex films due to surfactant

Gundabala, Venkata R.; Routh, Alexander F.

doi:10.1016/j.jcis.2006.07.016

Cited by 12 publications

(13 citation statements)

References 30 publications

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“…Water evaporation and a nonuniform surfactant concentration have however been shown to result in a contraction (thinning) of a drying latex film. 59 The onset of the contraction seen in the DQ p -T p curve [ Fig. 1(A)] coincides with the T g value (538C) determined by DSC, as well as with the melt onset temperature (508C) measured by TMA for Latex A (low-T g component).…”

Section: Resultssupporting

confidence: 77%

Thermal analysis and topographical characterization of films of styrene‐butadiene blends

Ihalainen

Backfolk

Sirviö

et al. 2008

J of Applied Polymer Sci

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Scanning probe microscopy (SPM) was used to study the thermal characteristics of latex films consisting of blends of two different styrene-butadiene copolymers with different glass transition temperatures (T g ). The resonance frequency (x) and the quality factor (Q p ) of an SPM probe oscillating above the sample surface were determined at different probe temperatures (T p ). Thermal transitions associated with a change in heat capacity were observed in the Dx-T p curves. The results were compared with differential scanning calorimetry measurements. The very slow heating rate used in the SPM method effectively eliminated the contribution of volumetric changes of the films around T g . Annealing of the samples in an oven did not influence the thermal transitions observed in the Dx-T p curves. The SPM method also enabled a novel approach for determining transition-induced dimensional changes (vertical contraction, expansion) of the films. Annealing was found to increase the dimensional stability of the blend films. The latex blends were also annealed by the SPM probe and the film progressed from particulate phase morphology to a continuous phase.

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Section: Resultssupporting

confidence: 77%

Thermal analysis and topographical characterization of films of styrene‐butadiene blends

Ihalainen

Backfolk

Sirviö

et al. 2008

J of Applied Polymer Sci

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“…Within the lubrication approximation, combining the Navier‐Stokes equation in the absence of inertia and gravity with the continuity equation, and satisfying the boundary conditions (tangential stress balance at the air‐film interface and no‐slip condition at the substrate) gives the expression for horizontal velocity as The derivation of Eq. 2 from first principles is given in an earlier publication13 and is not elaborated here. The expression for pressure in Eq.…”

Section: Lubrication Theorymentioning

confidence: 99%

“…In a previous publication,13 we investigated the influence of surfactant on the evolution of thickness of a latex film during the drying process. The surfactant spreading was spurred by an initial gradient in surface concentration.…”

Section: Introductionmentioning

confidence: 99%

Lateral surface nonuniformities in drying latex films

Gundabala

Lei

Ouzineb³

et al. 2008

AIChE Journal

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The length scales of film thickness non-uniformities, commonly observed in polymer colloid (i.e. latex) films, are predicted. This prediction is achieved by investigating the stability behaviour of drying latex films. A linear stability analysis is performed on a base solution representing a uniformly drying latex film containing a surfactant. The analysis identifies film thickness non-uniformities over two length scales: long (millimetre) range (from lubrication theory) and short (micrometer) range (from nonlubrication theory). Evaporation and surfactant desorption into the bulk film are identified as the primary destabilizing mechanisms during drying. Experimental evidence through direct visualization and atomic force microscopy confirm the existence of non-uniformities over both length scales, which are shown to be functions of parameters such as initial particle volume fraction, surfactant amount and desorption strength, whilst being independent of drying rate.Published in JAIChE 54 (2008) 3092-3105

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“…While the model was developed for monolayer applications of surfactant, it has come to be applied both above [5] and near [4] the critical monolayer concentration Γ c , the concentration above which a single layer of surfactant molecules can no longer form. Similar models have been used to study thin films in bronchial systems [12], ocular systems including blinking dynamics [3], bulk solute transport [21], drying of latex paint [7,14,13], ink-jet printing [15], and secondary oil recovery [29,16].…”

Section: Introductionmentioning

confidence: 99%

Surfactant spreading on a thin liquid film: reconciling models and experiments

et al. 2014

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The spreading dynamics of surfactant molecules on a thin fluid layer is of both fundamental and practical interest. A mathematical model formulated by Gaver and Grotberg [10] describing the spreading of a single layer of insoluble surfactant has become widely accepted, and several experiments on axisymmetric spreading have confirmed its predictions for both the height profile of the free surface and the spreading exponent (the radius of the circular area covered by surfactant grows as t 1/4 ). However, these prior experiments have primarily utilized surfactant quantities exceeding (sometimes far exceeding) a monolayer. In this paper, we report that this regime is characterized by a mismatch between the timescales of the experiment and model, and additionally find that the spatial distribution of surfactant molecules differs substantially from the model prediction. For experiments performed in the monolayer regime for which the model was developed, the surfactant layer is observed to have a spreading exponent of less than 1/10, far below the predicted value, and the surfactant distribution is also in disagreement. These findings suggest that the model is inadequate for describing the spreading of insoluble surfactants on thin fluid layers.

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Thinning of drying latex films due to surfactant

Cited by 12 publications

References 30 publications

Thermal analysis and topographical characterization of films of styrene‐butadiene blends

Thermal analysis and topographical characterization of films of styrene‐butadiene blends

Lateral surface nonuniformities in drying latex films

Surfactant spreading on a thin liquid film: reconciling models and experiments

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