Photo-Oxidation Mechanisms in Wool. A Study of the Photoprotective Effect of a Thiourea/Formaldehyde Treatment

Leaver, Ian H.

doi:10.1177/004051757804801010

Cited by 11 publications

(14 citation statements)

References 19 publications

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“…TUF-treated fabric was initially whiter than NACFtreated and thiourea dioxide-formaldehyde (TUDF)treated fabrics and did not demonstrate photobleaching after 2 h exposure to simulated sunlight. This result differs from that previously reported on TUF-treated peroxide-bleached wool by Leaver, who observed photobleaching during the first 25 h of exposure to simulated sunlight [8]. This difference is because of the far more rapid yellowing of wool that occurs in the presence of a FWA [14].…”

Section: Resultscontrasting

confidence: 98%

“…Figure 4 shows the fluorescence excitation and emission spectra of natural wool in the UV region following the various treatments. Whilst treatment with NACF increases the Trp fluorescence intensity, TUF quenches it, as previously reported [8]. The increase caused by NACF is probably as a result of reduction of disulphide bonds in the wool fibre to thiol groups by NAC.…”

Section: Resultssupporting

confidence: 81%

“…Our interest in the effects of these treatments on the intrinsic fluorescence of wool was stimulated by the previous work of Leaver [8]. He found an apparent linear relationship between the fluorescence emission intensity of the tryptophan (Trp) residues in natural and bleached wool before and after TUF treatment and the rate of photoyellowing when exposed to UVB radiation in the range k 290-320 nm for various periods.…”

Section: Resultsmentioning

confidence: 99%

“…The mechanism of TUF photoprotection for natural wool involves quenching of singlet and triplet excited states in wool protein and an increased rate of photobleaching by visible light [8]. This quenching effect of TUF on wool is very similar to the effect of iodide ions on polyamide polymers.…”

Section: Introductionmentioning

confidence: 93%

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Mechanism of photoprotection of wool with formaldehyde and thiol derivatives

Millington

Maurdev

Jones

2009

Coloration Technology

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The application of thiourea and formaldehyde offers significant reductions in photoyellowing for natural, bleached and fluorescent‐brightened wools. We have examined the use of alternative thiol derivates to thiourea and shown that a mixture of N‐acetylcysteine and formaldehyde is similarly effective. Photo‐induced chemiluminescence studies on treated wool fabrics show that the intensity of chemiluminescence following a brief exposure to ultraviolet A radiation is reduced for wool treated with thiourea and formaldehyde, N‐acetylcysteine–formaldehyde and thiourea dioxide–formaldehyde, but not for formaldehyde alone. This demonstrates that a lower population of free radicals is formed in irradiated thiol‐derivative formaldehyde‐treated wools because of free radical scavenging by the sulphur‐containing species. This free radical scavenging results in reduced photoyellowing. The effect of thiourea and formaldehyde treatment on the intrinsic fluorescence of wool is significantly different to N‐acetylcysteine–formaldehyde. Thiourea and formaldehyde quenches tryptophan fluorescence relative to untreated wool, whereas N‐acetylcysteine–formaldehyde treatment results in an increase in intensity probably because of a reduction in disulphide quenching.

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Section: Resultscontrasting

confidence: 98%

Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 93%

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Mechanism of photoprotection of wool with formaldehyde and thiol derivatives

Millington

Maurdev

Jones

2009

Coloration Technology

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“…Smith and Harris [10] observed the release of H2S from wool under powerful UV irradiation. Although much work has been done on the photochemistry of wool the exact mechanism for its photodegradation remains unclear [14][15][16][17]. Although much work has been done on the photochemistry of wool the exact mechanism for its photodegradation remains unclear [14][15][16][17].…”

Section: Discussionmentioning

confidence: 99%

Wool and Reduced Sulphur Gases in Museum Air

Brimblecombe¹,

Shooter²,

Kaur³

1992

Studies in Conservation

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Maney Publishing and International Institute for Conservation of Historic and Artistic Works are collaborating with JSTOR to digitize, preserve and extend access to Studies in Conservation.Abstract-Wool releases a number of reduced sulphur gases during storage. The release is enhanced under UV and even sunlight irradiation or when hot (50'C). Carbonyl sulphide is the principal sulphur gas found, along with traces of carbon disulphide and, in the case of short wavelength irradiations (to 254nm), hydrogen sulphide. The presence of significant amounts of water (20-80% wool weight) markedly increases the release of COS and CS2. The results of our work agree well with general observations that suggest wool degrades through thermal or photochemical degradation of cystine-containing protein. Although wool releases COS over time it also slowly absorbs COS from air. The release of sulphur gases from fabrics into indoor museum air is probably not a critical issue considering the potential magnitude of other sources such as human bioeffluents. However, within display cases, problems are likely where wool, feathers or similar materials are displayed with metals.

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The action of a benzotriazole light stabilizer in wool. I. A diffuse reflectance analysis of UV screening

Leaver

1982

J. Polym. Sci. Polym. Chem. Ed.

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A procedure based on diffuse reflectance spectroscopy was developed to determine the UV screening effect of a benzotriazole light stabilizer in wool fabric. Expressions that enable the protective effect of the stabilizer to be calculated directly from reflectance data were derived. The dependence of the screening effect on additive concentration was deduced from measurements of fabric reflectivity in the wavelength range of 300–400 nm. Two reflectometers with quite different optical geometries were used to measure the reflectance spectra and the merits of the two systems are discussed. A theoretical expression for the optical screening phenomenon in highly scattering materials was evaluated for substrates of different reflectivity and the general implications of this relationship are considered.

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Photo-Oxidation Mechanisms in Wool. A Study of the Photoprotective Effect of a Thiourea/Formaldehyde Treatment

Cited by 11 publications

References 19 publications

Mechanism of photoprotection of wool with formaldehyde and thiol derivatives

Mechanism of photoprotection of wool with formaldehyde and thiol derivatives

Wool and Reduced Sulphur Gases in Museum Air

The action of a benzotriazole light stabilizer in wool. I. A diffuse reflectance analysis of UV screening

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