Thermal Induced Changes in Cuticle and Cortex of Chemically Treated Hair

December 2025 in “ Biopolymers ”

Cibele Rosana Ribeiro de Castro Lima, Andrea Camara Bandeira, Tereza S. Martins, Larissa Otubo, Cristiano L. P. Oliveira

acid straightening bleaching FTIR/ATR SEM USAXS SAXS WAXS hair fibers cuticle cortex hair straightening hair bleach

Studysummary This study found that chemically treated hair, particularly when subjected to both acid straightening and bleaching, experiences more significant structural damage when exposed to heat, highlighting key changes in both the internal and surface components of hair fibers. Our plain-language summary of this paper — not a Tressless recommendation.

The study examines the effects of thermal and chemical treatments on hair, focusing on structural changes in the cuticle and cortex. Techniques like x-ray scattering and electron microscopy reveal that treatments such as bleaching and acid straightening, especially when combined with heat, cause significant damage, including melanin degradation, cuticle detachment, and breakdown of structural components like 18-MEA and disulfide bonds. These changes result in increased fragility, porosity, and irreversible damage, affecting hair's mechanical properties and appearance. The research underscores the need for safer cosmetic formulations and further investigation into these treatments' effects.

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research Straight to the Point: What Do We Know So Far on Hair Straightening?

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research Heat-Damaged Evaluation of Virgin Hair

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research Local Structure of Human Hair Spatially Resolved by Sub-Micron X-Ray Beam

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This study discovered a new region in the hair cortex where intermediate filaments are both aligned with the hair's axis and orientationally ordered, influenced by the cuticle boundary.

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37 citations , October 2015 in “PeerJ”

This study found that shampoo and conditioner do not alter hair's molecular structure, while perming treatments significantly affect keratin and intermediate filament structures due to bond alterations.

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research Distribution and Localization of Hydrophobic and Ionic Chemical Groups at the Surface of Bleached Human Hair Fibers

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This study concluded that bleach treatment partly transforms the hydrophobic top layer of human hair cuticles into a hydrophilic surface with clustered cysteic acid, visualized at the nano-scale using dynamic Chemical Force Microscopy.

research Investigating the Origins of Nanostructural Variations in Differential Ethnic Hair Types Using X-Ray Scattering Techniques

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research Analysis of Structural Change in Keratin Fibers Resulting from Chemical Treatments Using Raman Spectroscopy

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research The Intermediate Filament Architecture as Determined by X-Ray Diffraction Modeling of Hard Alpha-Keratin

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