Viscoelastic relaxation of insoluble monomolecular films

Earnshaw, J. C.; McGivern, R. C.; Winch, P.J.

doi:10.1051/jphys:019880049070127100

Cited by 47 publications

(44 citation statements)

References 44 publications

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“…The fitted values of γ′ are small and fluctuate considerably, but the general trend of the data is similar to that observed for adsorbed films of cetyltrimethylammonium bromide and sodium dodecyl sulfate, as well as for spread monolayers of various materials. 26,33 The nonzero values of γ′ at low c are supported by the rather large capillary wave damping at these concentrations, as noted above. In view of the small magnitude of γ′ it is probably not surprising that we do not observe any q variation of this surface viscosity.…”

Section: Transverse Shear Modulusmentioning

confidence: 78%

Transitional Behavior in Adsorbed Layers ofn-Decanoic Acid at the Air/Water Interface

et al. 1996

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The surface viscoelasticity of aqueous solutions of surface chemically pure n-decanoic acid has been studied by light scattering from thermally excited capillary waves of frequency between 5 × 10 4 and 9 × 10 5 s -1 . The surface dilatational elastic modulus measured by light scattering, corresponding to such frequencies, agrees with the equilibrium value derived from the π-ln(c) variation for concentrations below 8 × 10 -6 M and above 6 × 10 -5 M, but systematically exceeds the equilibrium variation between these concentrations. This intermediate concentration range has been described as one of transition between two different states of adsorption (Lunkenheimer and Hirte, J. Phys. Chem. 1992, 96, 8683). The behavior of the elastic modulus can be explained by relaxation involving molecular reorientation within the adsorbed layer, with a relaxation time . 4 µs. Such reorientation would be entirely consistent with a change of adsorption state, such as has been suggested for this system. Other aspects of the surface viscoelasticity are briefly discussed.

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Section: Transverse Shear Modulusmentioning

confidence: 78%

Transitional Behavior in Adsorbed Layers ofn-Decanoic Acid at the Air/Water Interface

et al. 1996

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“…By properly accounting [8] for the instrumental broadening, 7 and rj may be obtained from the power spectra. SLLS has also been used to study monolayers [13] and polymer films [14] deposited on liquid surfaces.…”

Section: First Observation Of Capillary To Rayleigh Mode Crossover Onmentioning

confidence: 99%

First observation of capillary to Rayleigh mode crossover on the surface of polymer solutions

Dorshow¹,

Turkevich²

1993

Phys. Rev. Lett.

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Using surface laser light scattering spectroscopy, we have observed for the first time the crossover from capillary to Rayleigh (elastic) surface fluctuations on polymer solutions. At low polymer concentrations c c* the capillary mode evolves into a Rayleigh mode. The surface laser light scattering data is quantitatively discussed within the context of recent theory.The surface tension [l] and bulk hydrodynamics [2] of polymer solutions have been the subject of extensive recent study. However, their surface hydrodynamics has received only scant attention [3][4][5][6][7]. The anomalous damping of capillary waves due to the frequency dependence of the bulk viscosity has been probed both for rigid rod solutions (carboxymethyl cellulose in water [5]) and for semidilute flexible polymer solutions (polystyrene in ethylmethylcetone [6] and polyisobutylene in decane [7]). However, surface Rayleigh waves, driven by the (visco)-elasticity of the underlying bulk solutions, have never been observed.Early theoretical treatments of polymer surface modes modeled the bulk material as a single-component viscoelastic fluid [3], which approach assumes a constitutive equation. By contrast, the coupled two-component fluid theory [4] deduces an appropriate constitutive equation in order to study the surface modes on entangled polymer solutions. These authors argue for a crossover from capillary (surface tension) to Rayleigh (surface elastic) modes as a function of polymer concentration. At low polymer concentration, the surface restoring force is dominated by the solvent surface tension; the surface fluctuation is a capillary mode with dispersion relation co -q 3 ' 2 . At high polymer concentration, the restoring force is enhanced, being dominated by the elasticity of the polymer entanglements (which elasticity increases with polymer concentration); the surface fluctuation is a Rayleigh mode with dispersion relation co -q. In this Letter, we report the first observations, using surface laser light scattering (SLLS) spectroscopy, of this crossover with polymer concentration from capillary to Rayleigh waves on the surfaces of polymer solutions.

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“…The surface properties are shown versus the capillary wave frequency merely to provide a possibility to fit with the Maxwell model. 22 Such a fit gives information on a characteristic relaxation time of strains in a liquid system. 22 However any attempts to fit the data of ␥ 0 led to very controversial estimates of the best fit parameters ͑sometimes even negative͒.…”

Section: Direct Spectral Fitmentioning

confidence: 99%

“…22 Such a fit gives information on a characteristic relaxation time of strains in a liquid system. 22 However any attempts to fit the data of ␥ 0 led to very controversial estimates of the best fit parameters ͑sometimes even negative͒. One can conclude that the fit failed to derive the meaningful estimates due to too high scatter of the ␥ 0 points.…”

Section: Direct Spectral Fitmentioning

confidence: 99%

Light scattering study of viscoelastic properties of a liquid Gallium surface

Kolevzon

1997

The Journal of Chemical Physics

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Articles you may be interested inHigh-precision instrument for measuring the surface tension, viscosity and surface viscoelasticity of liquids using ripplon surface laser-light scattering with tunable wavelength selection Rev. Sci. Instrum. 85, 044904 (2014); 10.1063/1.4871992 Ripplon on high viscosity liquid Rev. Sci. Instrum. 80, 014902 (2009); 10.1063/1.3072604 Shear small-angle light scattering studies of shear-induced concentration fluctuations and steady state viscoelastic properties Effects of viscoelasticity of bulk polymer solution on the surface modes as probed by laser light scatteringHigh frequency capillary waves on a liquid Gallium surface were studied by quasi-elastic light scattering spectroscopy. The observed damping constants of the waves differ greatly from the predictions of classical theoretical treatment of the surface as that of a simple liquid. This is explained in terms of the presence of a surface layer possessing visco-elastic properties which are extracted from the fit of experimental spectra using different theoretical forms. One of the most important results of the data analysis is that the surface dilational viscosity appears to be negative. This result implies that the widely used phenomenological theoretical model should be replaced by one taking into account processes of adsorption and diffusion. © 1997 American Institute of Physics. ͓S0021-9606͑97͒50912-3͔ ⌫ϭq 2 , ͑2͒ 5816

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Viscoelastic relaxation of insoluble monomolecular films

Cited by 47 publications

References 44 publications

Transitional Behavior in Adsorbed Layers ofn-Decanoic Acid at the Air/Water Interface

Transitional Behavior in Adsorbed Layers ofn-Decanoic Acid at the Air/Water Interface

First observation of capillary to Rayleigh mode crossover on the surface of polymer solutions

Light scattering study of viscoelastic properties of a liquid Gallium surface

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