The rigidity of wool and its change with adsorption of water vapour

Speakman, J. B.

doi:10.1039/tf9292500092

Cited by 75 publications

(25 citation statements)

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“…The mechanical properties of mammalian a-keratins are strongly influenced by moisture [11][12][13][14][15][16]. The avian and reptilian form, b-keratin, has been studied to a lesser extent [17][18][19], with similar results.…”

Section: Introductionsupporting

confidence: 52%

Effects of humidity on the mechanical properties of gecko setae

et al. 2011

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Section: Introductionsupporting

confidence: 52%

Effects of humidity on the mechanical properties of gecko setae

et al. 2011

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“…Thus Speakman found that wool immersed in water or alcohol is less resistant to extension than dry wool39 and that the presence of water decreased the rigidity of wool fibers. 40 The view that initial sorption by dry wool is mainly onto side-chain polar groups is supported by comparing activation energies of diffusionl0.41 and heats of hydration' for the wool-water system with the values obtained for the individual polar groups. It is found that the forces of sorption at low relative humidities are approximately what would be expected if the sidechain polar groups participated in the initial sorption of water by wool.…”

Section: Resultsmentioning

confidence: 99%

Sorption of liquids by wool. Part IV. Sorption of ethanol by modified wool

Leeder

Lipson

1963

J of Applied Polymer Sci

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INTRODUCI'IONThe sorption of polar liquids and vapors by proteins is considered to occur initially by hydrogen bonding at polar groups in the protein.'-l These polar sorption sites are mainly side-chain amino, carboxyl, and hydrmyl groups and peptide l i i g e s of the polypeptide ohaiins. However, there is some doubt as to whether it is side-chain polar groups or peptide links which form the main attractive sites for initial sorption.'-'There is some reported research on the.effect of side-chain masking on water sorption properties of proteins. Mellon et a1.6 found that. blocking of amino groups of casein by benzoylation decreased the sorption of water vapor. Modifications of the polar side-chains of wool results in decreased equilibrium sorption of water vapor at low or intermediate vapor pressureas-" usually without greatly affecting rate or equilibrium sorption at saturated vapor pressure. Kanagy and C a~s e l '~ found that sorption of water vapor by collagen is decreased by deamination, acetylation, and methylation.With wool, the surface scale structure can be a complicating factor in sorption studies. Although chemical and physical attack on these surface scales increases the rate of uptake of dyes1a-16 the sorption of water is unaffected. 11*18It might also be expected that physical modification of wool would produce changes in sorption behavior due to rearrangement of the polar groups and alterations in accessibility, but it has been found that severe physical changes, including supercontraction, reduction and even complete dissolution and reprecipitation, do not greatly affect the equilibrium sorption of water vapor at relative humidities up to 93%.16 Heat denaturation of egg albumin results in very little change in water-sorbing properties, but surprisingly, the sorption of ethanol is greatly This can be explained by assuming that because of their sma? size and high polarity, water molecules are sorbed extremely rapidly, attaching to polar sites with strong hydrogen bonds in such a way that even large changes in the chemical and physical properties of proteins produce little observed effect on the rate of sorption of water. By using larger and less polar molecules such as alcohols, which are sorbed much more slowly 2053

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“…11) clearly separates out the component of mechanical behavior responsible for the Post-Yield region. The initial levels of stress at each extension of nearly 3 and 8 ϫ 10 7 Pa, respectively at the 1-min level, were both at near equilibrium at the 200-min level at a stress of just under 2 ϫ 10 7 Pa. The stress relaxation for strains in the Post-Yield region contains a component of stress above that in the Yield region with a half amplitude time of about 10 min at 45°C.…”

Section: Post Yield Regionmentioning

confidence: 97%

Natural protein fibers

Feughelman

2001

J of Applied Polymer Sci

122

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Alpha keratin fibers (hairs, wools, quills, and other mammalian appendages) together with fibroin fibers such as silks and spiders webs are all highly extensible fibrous proteins for which the mechanical properties are of primary importance both to the animal from which they originate and their ultimate application by man. Similarly, the collagens are highly inextensible fibrous proteins, which form the major component of mammalian skin and connecting structures such as tendons. All these fibrous proteins are biological polymers of polypeptide chains for which the mechanical and allied physical properties, such as water absorption, relate to both their macrostructure and their molecular and near-molecular structure. Because of both their commercial application and their relatively complex structure at the molecular and near-molecular level, interpretation of the physical properties of ␣-keratin fibers represents the main component of this presentation. The mechanical properties of ␣-keratin fibers are primarily related to the two components of the elongated cortical cells, the highly ordered intermediate filaments (microfibrils) which contain the ␣-helices, and the matrix in which the intermediate filaments are embedded. The matrix consists of globular proteins plus water, the content of the latter being dependent on the fibers environment. The Extended Two-Phase Model (ETPM) has been developed and results in a detailed coverage of the bulk mechanical properties of ␣-helical fibers in terms of their known molecular and near-molecular structure. The inextensible protein fibers, the collagens and fibroins, are also briefly discussed in terms of the relationship between mechanical properties and the structure of these fibers.

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The rigidity of wool and its change with adsorption of water vapour

Cited by 75 publications

References 0 publications

Effects of humidity on the mechanical properties of gecko setae

Effects of humidity on the mechanical properties of gecko setae

Sorption of liquids by wool. Part IV. Sorption of ethanol by modified wool

Natural protein fibers

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