Strain and Strain Recovery of Human Hair from the Nano- to the Macroscale
In this study, in operandi SAXS experiments were conducted on samples of human hair with a varying degree of strain (2% within the elastic region and 10% beyond). Four different features in the SAXS patterns were evaluated: The intermediate filament distance perpendicular to and the distance from th...
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MDPI AG
2023-11-01
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| Series: | Life |
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| Online Access: | https://www.mdpi.com/2075-1729/13/12/2246 |
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| author | Brigitte Waldmann Martin F. T. Hassler Alexander R. M. Müllner Stephan Puchegger Herwig Peterlik |
| author_facet | Brigitte Waldmann Martin F. T. Hassler Alexander R. M. Müllner Stephan Puchegger Herwig Peterlik |
| author_sort | Brigitte Waldmann |
| collection | DOAJ |
| description | In this study, in operandi SAXS experiments were conducted on samples of human hair with a varying degree of strain (2% within the elastic region and 10% beyond). Four different features in the SAXS patterns were evaluated: The intermediate filament distance perpendicular to and the distance from the meridional arc in the load direction, as well as the distances of the lipid bilayer peak in and perpendicular to the load direction. From the literature, one concludes that polar lipids in the cuticle are the origin of the lipid peak in the SAXS pattern, and this study shows that the observed strain in the lipids is much lower than in the intermediate filaments. We support these findings with SEM micrographs, which show that the scales in the cuticle deform much less than the cortex. The observed deformation of the intermediate filaments is very high, about 70% of the macrostrain, and the ratio of the transverse strain to the longitudinal strain at the nanoscale gives a Poisson ratio of ν<sub>nano</sub> = 0.44, which is typical for soft matter. This work also finds that by varying the time period between two strain cycles, the typical strain recovery time is about 1000 min, i.e., one day. After this period, the structure is nearly identical to the initial structure, which suggests an interpretation that this is the typical time for the self-healing of hair after mechanical treatment. |
| first_indexed | 2024-03-08T20:36:20Z |
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| id | doaj.art-e882f3f2de534355b85b3c8f25cc18e1 |
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| issn | 2075-1729 |
| language | English |
| last_indexed | 2024-03-08T20:36:20Z |
| publishDate | 2023-11-01 |
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| spelling | doaj.art-e882f3f2de534355b85b3c8f25cc18e12023-12-22T14:21:04ZengMDPI AGLife2075-17292023-11-011312224610.3390/life13122246Strain and Strain Recovery of Human Hair from the Nano- to the MacroscaleBrigitte Waldmann0Martin F. T. Hassler1Alexander R. M. Müllner2Stephan Puchegger3Herwig Peterlik4Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, AustriaFaculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, AustriaFaculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, AustriaFaculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, AustriaFaculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, AustriaIn this study, in operandi SAXS experiments were conducted on samples of human hair with a varying degree of strain (2% within the elastic region and 10% beyond). Four different features in the SAXS patterns were evaluated: The intermediate filament distance perpendicular to and the distance from the meridional arc in the load direction, as well as the distances of the lipid bilayer peak in and perpendicular to the load direction. From the literature, one concludes that polar lipids in the cuticle are the origin of the lipid peak in the SAXS pattern, and this study shows that the observed strain in the lipids is much lower than in the intermediate filaments. We support these findings with SEM micrographs, which show that the scales in the cuticle deform much less than the cortex. The observed deformation of the intermediate filaments is very high, about 70% of the macrostrain, and the ratio of the transverse strain to the longitudinal strain at the nanoscale gives a Poisson ratio of ν<sub>nano</sub> = 0.44, which is typical for soft matter. This work also finds that by varying the time period between two strain cycles, the typical strain recovery time is about 1000 min, i.e., one day. After this period, the structure is nearly identical to the initial structure, which suggests an interpretation that this is the typical time for the self-healing of hair after mechanical treatment.https://www.mdpi.com/2075-1729/13/12/2246human hairin operandi SAXSmechanical propertiesnanostructurehierarchical materials |
| spellingShingle | Brigitte Waldmann Martin F. T. Hassler Alexander R. M. Müllner Stephan Puchegger Herwig Peterlik Strain and Strain Recovery of Human Hair from the Nano- to the Macroscale Life human hair in operandi SAXS mechanical properties nanostructure hierarchical materials |
| title | Strain and Strain Recovery of Human Hair from the Nano- to the Macroscale |
| title_full | Strain and Strain Recovery of Human Hair from the Nano- to the Macroscale |
| title_fullStr | Strain and Strain Recovery of Human Hair from the Nano- to the Macroscale |
| title_full_unstemmed | Strain and Strain Recovery of Human Hair from the Nano- to the Macroscale |
| title_short | Strain and Strain Recovery of Human Hair from the Nano- to the Macroscale |
| title_sort | strain and strain recovery of human hair from the nano to the macroscale |
| topic | human hair in operandi SAXS mechanical properties nanostructure hierarchical materials |
| url | https://www.mdpi.com/2075-1729/13/12/2246 |
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