Porosity at Different Structural Levels in Human and Yak Belly Hair and Its Effect on Hair Dyeing
Yak belly hair was proposed as a cheap substitute for human hair for the development of hair dyes, as its chemical composition closely resembles human hair in Raman spectroscopy. The absence of melanin in yak belly hair also leads to a strong reduction of fluorescence in Raman measurements, which is...
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| Format: | Article |
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MDPI AG
2020-05-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/25/9/2143 |
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| author | Alexander R. M. Müllner Ruben Pahl Doris Brandhuber Herwig Peterlik |
| author_facet | Alexander R. M. Müllner Ruben Pahl Doris Brandhuber Herwig Peterlik |
| author_sort | Alexander R. M. Müllner |
| collection | DOAJ |
| description | Yak belly hair was proposed as a cheap substitute for human hair for the development of hair dyes, as its chemical composition closely resembles human hair in Raman spectroscopy. The absence of melanin in yak belly hair also leads to a strong reduction of fluorescence in Raman measurements, which is advantageous for the investigation of the effectivity of hair dyes. To assess the suitability for replacing human hair, we analyzed similarities and differences of both hair types with a variety of methods: Raman spectroscopy, to obtain molecular information; small-angle X-ray scattering to determine the nanostructure, such as intermediate filament distance, distance of lipid layers and nanoporosity; optical and scanning electron microscopy of surfaces and cross sections to determine the porosity at the microstructural level; and density measurements and tensile tests to determine the macroscopic structure, macroporosity and mechanical properties. Both types of hair are similar on a molecular scale, but differ on other length scales: yak belly hair has a smaller intermediate filament distance on the nanoscale. Most striking is a higher porosity of yak belly hair on all hierarchical levels, and a lower Young’s modulus on the macroscale. In addition to the higher porosity, yak belly hair has fewer overlapping scales of keratin, which further eases the uptake of coloring. This makes, on the other hand, a comparison of coloring processes difficult, and limits the usefulness of yak belly hair as a substitute for human hair. |
| first_indexed | 2024-03-10T20:03:12Z |
| format | Article |
| id | doaj.art-2a3fd8402e0f4b4a91350e41219e1c16 |
| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-10T20:03:12Z |
| publishDate | 2020-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj.art-2a3fd8402e0f4b4a91350e41219e1c162023-11-19T23:26:03ZengMDPI AGMolecules1420-30492020-05-01259214310.3390/molecules25092143Porosity at Different Structural Levels in Human and Yak Belly Hair and Its Effect on Hair DyeingAlexander R. M. Müllner0Ruben Pahl1Doris Brandhuber2Herwig Peterlik3Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, AustriaLIM Cosmetics GmbH, Fugbachgasse 17/3-5, A-1020 Vienna, AustriaLIM Cosmetics GmbH, Fugbachgasse 17/3-5, A-1020 Vienna, AustriaFaculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, AustriaYak belly hair was proposed as a cheap substitute for human hair for the development of hair dyes, as its chemical composition closely resembles human hair in Raman spectroscopy. The absence of melanin in yak belly hair also leads to a strong reduction of fluorescence in Raman measurements, which is advantageous for the investigation of the effectivity of hair dyes. To assess the suitability for replacing human hair, we analyzed similarities and differences of both hair types with a variety of methods: Raman spectroscopy, to obtain molecular information; small-angle X-ray scattering to determine the nanostructure, such as intermediate filament distance, distance of lipid layers and nanoporosity; optical and scanning electron microscopy of surfaces and cross sections to determine the porosity at the microstructural level; and density measurements and tensile tests to determine the macroscopic structure, macroporosity and mechanical properties. Both types of hair are similar on a molecular scale, but differ on other length scales: yak belly hair has a smaller intermediate filament distance on the nanoscale. Most striking is a higher porosity of yak belly hair on all hierarchical levels, and a lower Young’s modulus on the macroscale. In addition to the higher porosity, yak belly hair has fewer overlapping scales of keratin, which further eases the uptake of coloring. This makes, on the other hand, a comparison of coloring processes difficult, and limits the usefulness of yak belly hair as a substitute for human hair.https://www.mdpi.com/1420-3049/25/9/2143hairnanostructuremechanical propertiesSAXShair dyeporosity |
| spellingShingle | Alexander R. M. Müllner Ruben Pahl Doris Brandhuber Herwig Peterlik Porosity at Different Structural Levels in Human and Yak Belly Hair and Its Effect on Hair Dyeing Molecules hair nanostructure mechanical properties SAXS hair dye porosity |
| title | Porosity at Different Structural Levels in Human and Yak Belly Hair and Its Effect on Hair Dyeing |
| title_full | Porosity at Different Structural Levels in Human and Yak Belly Hair and Its Effect on Hair Dyeing |
| title_fullStr | Porosity at Different Structural Levels in Human and Yak Belly Hair and Its Effect on Hair Dyeing |
| title_full_unstemmed | Porosity at Different Structural Levels in Human and Yak Belly Hair and Its Effect on Hair Dyeing |
| title_short | Porosity at Different Structural Levels in Human and Yak Belly Hair and Its Effect on Hair Dyeing |
| title_sort | porosity at different structural levels in human and yak belly hair and its effect on hair dyeing |
| topic | hair nanostructure mechanical properties SAXS hair dye porosity |
| url | https://www.mdpi.com/1420-3049/25/9/2143 |
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