Kinetic Studies of the Wool-Water System

Watt, I. C.

doi:10.1177/004051756003000605

Cited by 61 publications

(13 citation statements)

References 18 publications

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“…A similar agreement for desorption has been found by flalv and Rol)('rts r 1('1, who used KinJ{'s data on horn keratin for the diffusion coemcient and compared the calculated curves with their experimental results obtained using thin layers of wool filrrs. 1n the 2 The shape and initial slope of the integral uptake curve found by the present method differ from the behavior found using a gravimetric method and a vacuum apparatus [22]. For example, in a step from 0 to 80% RH at 35° C. the initial slope using the vibroscope method is twice as great as with the vacuum apparatus, and the times taken to reach equilibrium are 3 min.…”

Section: Theoretical Appraisal Of Integral Sorptioncontrasting

confidence: 72%

Sorption Kinetics of Water Vapor in Wool Fibers: Evaluation of Diffusion Coefficients and Analysis of Integral Sorption

Nordon

Mackay

Downes

et al. 1960

Textile Research Journal

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A number of interval sorption experiments have been made and analyzed, assuming Fick's law; diffusion coefficients were derived. These coefficient have been used to predict the behavior in integral sorption; the disagreement between prediction and experiment is discussed. Integral sorption experiments have also been carried out on horse hairs of various diameters to trace the influence of diameter on the sorption rate. GeneralThe general shape of the'water sorption curve by wcx~l for small changes of relative humidity is well known I 1], 22 ~ ; it is very similar to those for water in cethnoso 18, 20) and for organic vapors in cellulose acetate 2 ~ . These curves may best he doscrihed in terms of a two-stage sorption process in which the first stage corresponds to H irkian diffusion and the second stage to a further uptake of sorhate the rate of which is not controlled ltv diffusion hut hy a molecular relaxation process of the sorbent.The exact nature of this relaxation process is not yet fully understood, although an approximate calcutation 121 has shown that it may he due to the relaxation of the elastic strain imposed on the polymer network 1>v the volume swotting accompanying the firat stage of sorption.In an attempt to analyze the observed kinetics of water sorption by wool, perhaps the most outstanding feature which requires explanation is the difference in the form of the uptake curves for small and large steps in relative hunndity. In the absence of a more appropriate theory, an analysis in terms of Fick's law has to 1>e undertaken. It has been shown by Crank 151 that, at least yualitativelv, the major characteristics of the sorption behavior of many polymer systems can be explained in terms of 1: ick's s law provided the diffusion coefficient is made a function of (a) the concentration, (b) I the time. and (c) the strain set up in the sorbent.The only available data for diffusion coemcients which may be applicable to the wool-water systemhave been reported hy King 17 J for horn keratin using a steady-state permeability method. King found that the steady-state diffusion coefbcient was a function of the concentration of the water in the keratin and published the curve relating regain and diffusion roefhcient. L'nfortunately, the physical form of the wool fiber makes it impossibte to devise a steady-state experiment hy which the concentration dependence of the diffusion coefhrient can he measured. One is forced, therefore, to aplroximate the required conditions of the measurement hy making the step of concentration as small as possible and assuming that. over the small range used, the coefficient is constant This type of experiment, however, does not rule out time or ,train effects.The small-step sorption experiments reported here were undertaken with a twofold purpose in view: to check whether agreement could be ohtained between diffusion coefficients for wool keratin and Iving'~ published figures for horn keratin and to find to what extent the sorption and desorption curves predicted by the concentration-...

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Section: Theoretical Appraisal Of Integral Sorptioncontrasting

confidence: 72%

Sorption Kinetics of Water Vapor in Wool Fibers: Evaluation of Diffusion Coefficients and Analysis of Integral Sorption

Nordon

Mackay

Downes

et al. 1960

Textile Research Journal

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“…Curve A of Figure 1, which shows absorption to saturation, reaches a iiiaxiniiini water content (mwc) of 53.570 and comes to an equilibrium water content (ewc) of 46.47Jo. This large overshoot of the equiIibriiiiii water content is the outstanding feature of the uptake curve coinpared to an overshoot of the order of 1.6% water content that has been reported [13] for the a1)sorption of water by unmodified ivool under similar esperinicntal conditions. The uptake of water vapor by unniodified u-001 after exposure to humidities of 100% RH and 66% RH are shoivn for comparison as dotted curves in Figure 1.…”

Section: Rcdirccd Nrid Alkjlntcd W O O Lsupporting

confidence: 49%

The Sorption Behavior of Cystine-Modified Wool

Watt

1963

Textile Research Journal

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The sorption behavior of \vool fibers with a reduced cgstine content has been studied, using water and forinic acid as sorbates. Reduction alone causes little change of the sorption behavior but reduction follon-ed by alkylntion of the sulfhydryl groups catises changes depending on the extent of reduction and the alkylation procedure.The water absorption isotherm of the alkylated wool is less than the corresponding isotherm of unmodified \vool until near-saturation humidities where the inter content becomes higher for the alkylated sarriples. For absorption at high humidities the uptake curves of reduced and methylated samples show large overshoots of water content above the equilibrium water content. For samples alkylated with al!cyl t1ih;tlides such that new cross-links are formed, the rate of uptake is less than for unmodified wool, but at saturation tlie water content is between that of uiiniodified wool and reduced and niethylated wool. The conversion of cystine to Ianthionine in \vool also leads to increased water contents at high humidities. The changes in sorption behavior of the modified wools are more marked when formic acid yapor is the sorbate.

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“…However, the overshoot was also larger the smaller the total uptake at equilibrium. The opposite behavior is observed for water uptake in wool fiber [39]. Such inconsistencies, which are related to the strong compositional dependencies of transport properties in polymers, serve to highlight further the limitations of simple viscoelastic models of diffusion.…”

Section: Discussionmentioning

confidence: 96%

Inertial effects and diffusion

McGahay

2004

Journal of Non-Crystalline Solids

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Kinetic Studies of the Wool-Water System

Cited by 61 publications

References 18 publications

Sorption Kinetics of Water Vapor in Wool Fibers: Evaluation of Diffusion Coefficients and Analysis of Integral Sorption

Sorption Kinetics of Water Vapor in Wool Fibers: Evaluation of Diffusion Coefficients and Analysis of Integral Sorption

The Sorption Behavior of Cystine-Modified Wool

Inertial effects and diffusion

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