The effect of water on the glass transition of human hair

Wortmann, Franz; Stapels, M; Elliott, R.O.; Chandra, L.

doi:10.1002/bip.20429

Cited by 60 publications

(68 citation statements)

References 89 publications

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“…5 For a soluble protein, this process is claimed to be a reversible, one-step, first-order transition. 8,9 However, in practice, even in complex heating and cooling programs, as implemented in the context of another investigation, 10 no indication was found that the denaturation process for the insoluble hair keratin may be to any extent reversible, showing the primacy of kinetic control over the process, 9 which is exerted by the matrix surrounding the IFs. 5 The baseline for the DSC curves is generally a fairly straight line, indicating that there are no other major processes present.…”

Section: Discussionmentioning

confidence: 97%

Nonisothermal denaturation kinetics of human hair and the effects of oxidation

2006

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Human hair as alpha-keratin fiber exhibits a complex morphology, which for the context of this investigation is considered as a filament/matrix-composite, comprising the intermediate filaments (IF) and a variety of amorphous protein components as matrix. Differential scanning calorimetry (DSC) under aqueous conditions was used to analyze the denaturation of the alpha-helical material in the IFs and to assess the changes imparted by repeated, oxidative bleaching processes. The DSC curves were submitted to kinetic analysis by applying the Friedman method and assuming first order kinetics. It was found that the course of the denaturation process remains largely unchanged through oxidation, despite the fact that pronounced decreases of denaturation temperature as well as of enthalpy occur. In parallel, the reaction rate constant at the denaturation temperature, k(TD), increases with repeated treatments, that is with cumulative chemical modification. However, this effect is in fact small compared to the overall change of k(T) through the denaturation process. This leads to conclude that once the temperature rise in combination with the chemical change has induced a suitable drop of the viscosity of the matrix around the IFs, denaturation of the remaining helical material occurs along a pathway that is largely independent of temperature and of the pretreatment history. This emphasizes the kinetic control of the matrix over the denaturation process of the helical segments in the filament/matrix composite.

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Section: Discussionmentioning

confidence: 97%

Nonisothermal denaturation kinetics of human hair and the effects of oxidation

2006

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“…Several of the authors who researched the thermal analysis applied on human hair executed TG and DSC analyses with the purpose of characterizing the keratin of human hair [54][55][56] and verifying the effects of hair care products on keratin structure [15,57,58].…”

Section: Thermal Analysismentioning

confidence: 99%

In Vitro Methodologies to Evaluate the Effects of Hair Care Products on Hair Fiber

2017

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Consumers use different hair care products to change the physical appearance of their hair, such as shampoos, conditioners, hair dye and hair straighteners. They expect cosmetics products to be available in the market to meet their needs in a broad and effective manner. Evaluating efficacy of hair care products in vitro involves the use of highly accurate equipment. This review aims to discuss in vitro methodologies used to evaluate the effects of hair care products on hair fiber, which can be assessed by various methods, such as Scanning Electron Microscopy, Transmission Electron Microscopy, Atomic Force Microscopy, Optical Coherence Tomography, Infrared Spectroscopy, Raman Spectroscopy, Protein Loss, Electrophoresis, color and brightness, thermal analysis and measuring mechanical resistance to combing and elasticity. The methodology used to test hair fibers must be selected according to the property being evaluated, such as sensory characteristics, determination of brightness, resistance to rupture, elasticity and integrity of hair strain and cortex, among others. If equipment is appropriate and accurate, reproducibility and ease of employment of the analytical methodology will be possible. Normally, the data set must be discussed in order to obtain conclusive answers to the test.

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“…6 The water content in the dried hair was minimized (4.5% by weight). 6 A lock of 100 hairs (33 mm, 19.021.0 mg) was bundled up with a copper film (3.0 © 8.0 © 0.1 mm 3 ) and was degassed in vacuo. The sample was then sealed in an ESR quartz cell under dry helium atmosphere and was exposed to near-UV radiation at 77 K. 5 A Xe-lamp (UVF-203S, Sanei Electric, wavelength; 255 to 390 nm, 0.78 W cm…”

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“…13 Under the anaerobic condition used in the present study, the extended life-time of the thiyl radical might enable the addition of the neighboring disulfide bond to form the trisulfide neutral radical. In addition, the glass transition of the dried hair (T g µ 360 K) 6 also affects the formation of the SS bond linkage between the thiyl radical and disulfide moiety. Therefore, species III is formulated to be RSS(R)S…”

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confidence: 99%

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