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Mechanism of split-end formation in human head hair
Abstract
The satisfactory prevention or repair of "split ends" in long-hair styles continues to present a significant challenge to the toiletries industry. The mechanics by which they form has not been clarified previously. Combing is a common requirement, without which few split ends are formed (1,2). Splitting always occurs in the plane containing the hair's major elliptic diameter. A theoretical analysis supports the notion that during the combing of tangled hairs, high shear stresses are developed about the major elliptic diameters of the fibers. Shear fracture about this diameter and the further propagation of the fracture front towards the hair tip adequately explain the characteristic primary morphology of this cosmetically undesirable terminal bifurcation of the hair. Amongst the various factors that influence split-end formation, two are highlighted in that they offer prospects for simple modification to the cosmetic advantage of reducing the incidence of split ends. One is about reducing frictional interactions between hairs by lubrication and the other concerns improvements in the longitudinal shear plasticity within the hair's bulk.
... Together with the endocuticle the CMC from the non-keratinous regions which are becoming more and more important to cosmetic science because, they are believed to be the primary pathway for entry of diffusion of cosmetics into hair. [1,24] The cortex The cortex containing the major part of human hair and mainly consists of low sulphur keratin. [1] Several dozen microfibrils make up a cortical cell. ...
... The cuticle damage is caused by mechanical processes from the daily grooming actions like combing, scratching, cutting, washing, brushing, blow-drying, and sun rays. [6,24] The hair near scalp had complete cuticles while no cuticles were found near the tip. This may be because of the hair near the scalp. ...
Hair is one of the most important portions for beauty care and in recent years grooming and cosmetic treatment of hair has drastically risen. Substantially, it may deteriorate and weaken the hair by modification of keratin protein. This makes the hair dry, brittle and split vend occurs due to loss of hair strength and the damage further increases with cosmetic treatments. The various poor ingredients are being used for repairing which have extremely poor compatibility with hair. Now the hair care products can be introduced with an active ingredient comprising a yolk derived anti-hair antibody immunoglobin obtained from egg of chickens immunized with damaged hair as antigen. This immuno-cosmeceuticals can repair the hair damage and imparts flexibility and smoothness to the hair. These effects are not lost by the ordinary shampooing. This article focuses on the characteristic of human hair, its damaging processes and the effects of immuno-cosmeceuticals for repairing the hair damage.
... Repeated grooming (combing, brushing, etc.) of human hair exposed to chemical treatments (bleaching, perming, and relaxing), UV radiation, and exposure to thermal styling appliances often results in mechanical damage to the protective overlying cuticle cells, leading to their erosion and, further, often to the development of split ends [42]. Technically referred to as trichoptilosis, split ends are a splitting or fraying of the hair shaft. ...
Maleic anhydride and its derivatives are used in many different areas in personal care. They are indispensable ingredients used in hair, skin, and oral care formulations. In hair care applications, copolymers containing maleic anhydride are mostly found in hair fixative and styling formulas. They act as film formers, compatible with a variety of solvent systems, which form polymer-hair fiber assemblies with resistance to high humidity and mechanical insult to the hairstyle. The use of this type of chemistry in hair care has a long history that began in the 1950s and continues to find itself in contemporary products. In skin care, the largest impact of maleic anhydride chemistry is in the form of copolymers of maleic anhydride and methyl vinyl ether that are used in transdermal delivery systems and as bioadhesives for biomedical devices. In addition, there are many innovative uses of maleic anhydride chemistry in the delivery of cosmetic active ingredients as well as adjuvants in antiperspirant formulations. Moreover, copolymers of maleic anhydride function as rheology modifiers in finished skin care formulations providing desirable textural and sensorial properties for the consumer. In oral care, poly(methyl vinyl ether-maleic anhydride) is found in dentifrice formulations, where it acts as a bioadhesive, film former, and delivery vehicle for active ingredients. For many years, the bioadhesive nature of poly(methyl vinyl ether-maleic anhydride) to the oral mucosa has been exploited in denture adhesive formulations as the key active ingredient. In the pages that follow, we provide a summary and critical analysis of both historical and contemporary uses of maleic anhydride in the personal care arena focusing on traditional and innovative approaches.
... Although it is known that combing and derangling of dry hair contribute to the appearance of "split ends," the mechanism of damage is not clearly understood. Recently, it has been proposed that fracture at the hair tips by longitudinal shear stresses during derangling may explain "split end" formation (5). Cracks and hair fracture are, certainly, two necessary steps during "split end" formation; however, the occurrence of longitudinal cracks such as those observed in "split ends" rarely takes place in hair by the action of longitudinal stresses (6,7). ...
Plastic yielding in the form of crazing and shear bands was found to occur in human hair cuticles subjected to cyclical torsion stresses. This type of damage appeared in the form of helicoidal longitudinal strips around the main axis of the hair fiber following sections of maximum shear stress during twisting. The hair regions with shear bands and crazing were approximately 30 microns wide and 2 to 3 millimeters long and gave the appearance that the hair had partially lost its cuticles. SEM analysis revealed, however, that the cuticular material was still there, and that rather the damaged cuticular regions had lost their structure and boundaries because they were filled with microvoids, microcracks, and sometimes very narrow long vertical cracks. This type of plastic deformation was found to be a mechanism for dissipating mechanical energy in cuticles in response to the torsional shear stresses that are expected to attain a maximum value at the hair surface. Shear band and craze formation was found to be very sensitive to the moisture content in hair, and at high relative humidities it did not occur at all. Analysis of hair from a panel of 100 individuals showed that shear band and craze formation is also frequently found in hair collected from panelists who employed only conventional grooming practices. The effect of shear bands and crazes on split end formation is also discussed.
Herein is an attempt to bridge the gap between consumer and scientist by defining the more important consumer hair assembly properties (heads of hair, tresses, or wigs) describing how these properties are affected by changes from cosmetic treatments to fundamental single fiber properties. The effects of changes in single fiber properties by chronological age for five different stages of one’s life is also described in terms of how these fiber properties relate to and affect the important consumer hair assembly properties. The literature on hair breakage is also summarized as a multifactorial phenomenon involving tangle formation with hairs looped over other hairs, severe bending deformations, highly localized stresses, and the amount of water in the fibers. The effects of hair curvature, fiber twists, knots, hair damage and abrasive wear on hair breakage are also described. A new unpublished section describing split hairs found on the heads of consumers is described along with preferred mechanisms for the formation of these different types of split hairs.
Im folgenden wird eine Übersicht über die geometrischen und physikalischen Eigenschaften von Haaren gegeben. Unter geometrischen Eigenschaften werden die axiale und die radiale Struktur, sowie die Haarlänge verstanden. Die physikalischen Eigenschaften umfassen die Zug-, Biege- und Torsionssteifigkeit, viskoelastisches Verhalten und Hysterese, sowie den Einfluss von Feuchtigkeit, Temperatur und kosmetischen Behandlungen auf eben diese Größen. Dazu zählen au�erdem die Reibung und die optischen Eigenschaften.
The objective of the present study is to develop a novel nondestructive, simple, and quick method to evaluate the friction, twist, and gloss of human hair based on near-infrared diffuse reflectance (NIR-DR) spectroscopy and chemometrics. NIR-DR spectra were measured for human hair, which was collected from eleven Japanese women (age 5-44 years), by use of an optical fiber probe. Partial least squares (PLS) regression has been applied to the NIR-DR spectra of human hair after mean centering (MC), standard normal variate (SNV), and first derivative (1d) or second derivative (2d) analysis to develop calibration models that predict the friction, twist, and gloss of human hair. We identified the most suitable wavenumber region for the evaluation of each physical property. Correlation coefficients and standard errors of calibration of the PLS calibration models for the friction, twist, and gloss of hair were calculated to be 0.96 and 0.023, 0.81 and 3.27, and 0.90 and 0.36, respectively. Thus, the calibration models have high accuracy.
Split ends form through mechanical stresses during grooming procedures and are more likely to appear in hair damaged as a result of excessive combing forces. Although there are no conventional systems that will permanently mend split ends, a semi-permanent mending composition has been achieved through a polyelectrolyte complex. The complex is formed as a result of the ionic association of a cationic polymer, Polyquaternium-28, and an anionic polymer, PVM/MA Copolymer. Hair tresses containing tagged split ends are used in measuring mending efficacy. The tagging allows the fate of the split ends to be determined after different types of treatment regimens which test the durability of the mend. Monitoring of the repair and mending durability is carried out with the aid of a stereomicroscope. Results obtained with this method indicate that the complex both by itself and when formulated into a simple lotion provided a high level of split end mending not only after initial treatment but more importantly after combing showing the durability of the mend. Cumulative effects and durability to washing indicate that the polymer complex does not build up on the hair and rinses off with shampoo making possible its usage as a post shampoo treatment. The formulated lotion has higher durability performance as compared to a commercial product with a split end mending claim. The proposed mechanism of action entails a crosslinking microgel structure that infiltrates the damaged hair sites binding them together. This model is supported by the analysis of phase behavior, viscometry, Scanning Electron Microscopy, and absorption of ionic dyes.
Premature fracture and splitting of human head hair is cosmetically undesirable and at worse, unsightly. It is often regarded both by the hair's owner and by others as indicative of hair in poor condition and attracts considerable expenditure on hair toiletry products in sometimes vague attempts to prevent or repair the damage. This paper defines the mechanical events which underlie the fracture of hairs as they occur on the head and insofar as they satisfy the different fracture morphologies seen under the scanning electron microscope. Factors affecting propensity for fracture are considered. A significant conclusion is that hair 'strength', as might be assessed by the consumer, has little to do with the tensile mechanical properties of the fibres but that bending and associated longitudinal shear processes are of much greater relevance.
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