The effect of pH on the thermal stability of fibrous hard alpha-keratins

Istrate, Dan; Popescu, C.; Er-Rafik, Mériem; Möller, Martin

doi:10.1016/j.polymdegradstab.2012.12.001

Cited by 31 publications

(30 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In view of previous observations [48], the current conclusions are expected to apply similarly and more widely for damage induced in hair by radiation (UV, visible light, IR, heat) with due considerations of the synergistic role of water content. For other treatments, similar correlations are expected, which, however, may be qualitatively and quantitatively quite different compared to the current experimental context [49].…”

Section: Discussionsupporting

confidence: 51%

Linear and nonlinear relations between DSC parameters and elastic moduli for chemically and thermally treated human hair

Wortmann

Popescu

2019

J Therm Anal Calorim

Self Cite

View full text Add to dashboard Cite

Against the practical context of thermal straightening, hair samples were obtained with a chemical (bleaching) as well as a cumulative thermal history (0-800 s, 200°C). On these samples, tensile testing and DSC analysis, both in the wet state, were conducted to obtain the elastic moduli E w as well as denaturation temperatures T D and enthalpies DH D . 3D plots show overall linearity for the relationships between the parameters for natural hair. For bleached hair, pronounced nonlinearities develop beyond 300 s of thermal treatment. At this stage, T D as well as E w approaches limiting values, consistent with the state of a highly cross-linked, thermoset polymer. 2D projections are used to investigate the correlations between pairs of parameters. The results show that bleaching imparts a specific sensitivity for thermal damage, namely, to the matrix proteins, which more readily than the intermediate filaments (IF) turn into a thermoset. Overall, correlations between parameters hold well prior to the thermoset range. It is thus suggested that tensile testing to determine the elastic modulus and DSC come to consistent and equivalent results, at least, for the current experimental context. However, while E w combines contributions of IFs and matrix, DSC differentiates the specific property changes of these components.

show abstract

Section: Discussionsupporting

confidence: 51%

Linear and nonlinear relations between DSC parameters and elastic moduli for chemically and thermally treated human hair

Wortmann

Popescu

2019

J Therm Anal Calorim

Self Cite

View full text Add to dashboard Cite

show abstract

“…[] Using TG and DSC, Éhen et al evaluated the thermal decomposition of hair samples and found T D ~230‐233°C and thermal decomposition of the hair fiber after 250°C. According to Istrate et al, DSC experiments conducted in dry conditions (as the same carried out in this study) induce the occurrence of pyrolysis reactions and denaturation at similar temperatures (that is, overlapping events). Thus, the results obtained in this research indicate that the heat promotes both the denaturation of α‐keratin and decomposition of hair components and this affects the mechanical properties of the fibers, such as strength and elasticity.…”

Section: Discussionmentioning

confidence: 79%

“…Additionally, many people often perform more than two types of chemical procedures on their hair, associating with the thermal devices. Frequent changes in pH, incompatibility of these treatments, and exposure to heat produce damage in the hair that may be irreversible …”

Section: Introductionmentioning

confidence: 99%

“…More precisely, the microfibrils of the cortex can denature due to exposure to the heat. Differential scanning calorimetry (DSC) has been carried out to investigate the α‐ crystallites denaturation of the hair cortex . The literature relates that the cuticle hair layer has extended protein chains or β‐sheet structure conformations.…”

Section: Introductionmentioning

confidence: 99%

“…Differential scanning calorimetry (DSC) has been carried out to investigate the α-crystallites denaturation of the hair cortex. [2][3][4] The literature relates that the cuticle hair layer has extended protein chains or β-sheet structure conformations. A protein conformation modification can change the hydrogen bonding structure that stabilizes the helical structure and, therefore, may change the water accessibility to hair.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Heat‐damaged evaluation of virgin hair

Lima

Couto

Freire

et al. 2019

J of Cosmetic Dermatology

View full text Add to dashboard Cite

Summary Background Hair‐straightening treatments may involve the use of thermal devices, which potentially cause damages in the cuticle and cortex of the hair fibers. Particularly, the heat causes denaturation of the α‐keratin and the degradation of the components of the hair cortex. Objectives The aim of this study was to evaluate the effect of heating on the cuticle and cortex of the Caucasian and Asian virgin hair by using heat iron flat. Methods The effects of the heating in the tresses of Caucasian and Asian virgin hair were analyzed by thermogravimetry/differential scanning calorimetry‐Fourier transform infrared/mass spectrometry (TG/DSC‐MS/FTIR), protein loss analysis (PLA), Fourier transform infrared (FTIR‐ATR), and scanning electron microscope (SEM). Results TG/DSC‐MS/FTIR results were: formation of the H2O between 25‐170°C and CO2, SCO and H2S from 200°C. Denaturation temperature = 237°C. Protein loss: Asian hair>Caucasian hair. Data presented statistically significant alterations, α = 5, P ≤ 0.05, n = 3. FTIR‐ATR: changes in the secondary structural conformation of the protein of hair cuticle. SEM: heat caused damage to hair cuticle. Conclusions The results evidenced the importance of the control of temperature in the procedures involving heat. The damage caused by thermal devices showed be dependent of the ethnicity analyzed (Caucasian and Asian hair).

show abstract

Effect of equilibrium pH on the structure and properties of bleach‐damaged human hair fibers

et al. 2020

View full text Add to dashboard Cite

Hair proteins are significantly affected by environmental pH. This impact tends to increase with prior hair damage. To understand how pH affects bleached hair properties, we utilized a number of techniques allowing for the determination of hair thermal properties, swelling and water sorption, and dry and wet tensile properties. At pH 5, hair proteins had the best structural integrity, as determined by differential scanning calorimetry and the highest tensile modulus. At pH 10, protein cross-linking density decreased, water content and hair cross-sectional diameter increased. Alkaline treatment, when compared with pH 5, did not reduce intermediate filament conditions (evaluated via enthalpy measurement) nor mechanical property performance in the wet state. In contrast to alkaline-treated hair, bleached hair equilibrated at pH 3 behaved very differently: it contained two different crosslink density zones, was the least stiff in dry and stiffest in wet conditions. Additionally, it absorbed less water and had the lowest diameter because of reduced water binding by protonated carboxyl groups. The pH 3 to 10 did not affect the mechanical strength of bleached hair in dry or wet conditions.

show abstract

The effect of pH on the thermal stability of fibrous hard alpha-keratins

Cited by 31 publications

References 33 publications

Linear and nonlinear relations between DSC parameters and elastic moduli for chemically and thermally treated human hair

Linear and nonlinear relations between DSC parameters and elastic moduli for chemically and thermally treated human hair

Heat‐damaged evaluation of virgin hair

Effect of equilibrium pH on the structure and properties of bleach‐damaged human hair fibers

Contact Info

Product

Resources

About