46 HAIR CARE a b
6.0
4.0
2.0
0.0 0.10 1.00 10.00 100.00 Particle diameter (nm)
Figure 8a (left): Particle size analysis of Granrepair Powerbond (5% in water) having an average diameter of 5-50 nm. Figure 8b (right): Drave’s wetting test method performed with GRPB to demonstrate penetration ability.
summarised in Figure 5. The effect of bleaching conditions on hair has been studied by multiple groups and is known to reduce the structural integrity of hair.11,12 The data collected was focused on the highest force (grams-Force (gF)) and this corresponds to the maximum tensile strength of the hair fibre after different treatments conditions. After the first cycle, there is a slight decrease in the tensile strength for both functionalised dimethicone-treated (-4.3%) and control hair (-2.2%) tresses relative to the virgin hair tress. A dramatic drop in tensile strength was observed for the control hair tresses after the second (-17.4%) and third (-23.9%) cycles of bleaching relative to the virgin hair tress. Hair tresses treated with functionalised dimethicone during the bleaching process had improved strength compared to the control hair tress of the same bleaching cycle. The second and third bleaching with functionalised dimethicone had a gradual reduction in tensile strength (-8.7% and -15.2%, respectively). In addition, the third cycle with functionalised dimethicone is able to better preserve and strengthen the hair integrity compared to the second control cycle. The functionalised dimethicone was able to preserve the hair strength and improve conditioning attributes to minimise the damaging effects of the bleaching environment without hindering the bleaching process.
Scanning Electron Microscopy (SEM) displays hair fibre surface integrity l Method The hair tresses were bleached for 3 cycles as described previously and analysed by SEM for surface defects. l Results The area of the hair shaft that would be greatly affected by the damaging conditions of the bleaching process are the
PERSONAL CARE EUROPE
exposed tips of the hair. Functionalised dimethicone was able to successfully preserve the cuticle of the hair fibres, especially at the tips of the hair shaft (Fig 6). Despite ‘extreme’ conditions, the hair cuticles were left homogenous with no cortex exposure. The control hair tress that did not have any additive was severely damaged (Fig 7). The tips of the control hair tress had lost cuticle symmetry and the cortex was noticeably exposed. Preservation of the surface is crucial in maintaining the appearance and texture of healthy hair. By preserving the surface of the hair there is less damage internally, which translates to strengthened reinforced hair compared to the control.
Confirmation of the particle size of the microemulsion and penetration ability l Method
Particle size was analysed by Anton Paar Litesizer 500 following instrumental guidelines. Functionalised dimethicone was diluted to 5% in deionised water and transferred to a cuvette for analysis. The penetration ability of this microemulsion was confirmed by the use of the Drave’s Wetting Test Method.13
This test method is
used to test the permeability of a solution on a cotton skein. Briefly, a cotton skein was submerged by a mass into a graduated cylinder filled with a solution. As the skein absorbs water from the solution, it will sink to the bottom and the length of time to make the skein sink is recorded. l Results
The functionalised dimethicone concentrate is a translucent refractive index match microemulsion. Microemulsions are used in the cosmetic industry and are known to form spontaneously and are thermodynamically stable fine emulsions of oil, water and surfactant.14
The unique attribute of microemulsions are the size of
these emulsion droplets and its high surface area. It is therefore able to effectively penetrate the hair and transport itself to protect and preserve the hair integrity. The average droplet size of the functionalised dimethicone was found to be in the range of 10-50 nm (Fig 8a), typical of microemulsions. The penetration behaviour that was confirmed by “Evaluation of Wetting Agents by the Skein Test ASTM D2281 - 10(2016).” Different dilutions of the functionalised dimethicone (2, 5, 10% wt.) were made and found to sink the cotton skein in 6.5 min, 2.5 min, and 1.5 min, respectively (Fig 8b). The sinking of the cotton skein is indicative of the concentration and permeability of the formula of the functionalised dimethicone. the functionalised dimethicone was able outperform two commercialised products. When the cotton skein was submerged in water or in other water-soluble commercialised products there was no sinking of the cotton skein, even after 10 minutes. This suggests that water-soluble products under-perform in wetting and penetration of the hair compared to the functionalised dimethicone.
Conclusion Chemical treatments, such as, hair bleaching and oxidative hair colouring procedures greatly reduces hair integrity. These processes lead hair to be damaged, course and brittle. In addition, the hair if left untreated appears dull and frayed. Therefore, it is necessary to introduce an additive to assist and maintain the structural integrity of the hair by multiple actions. Granrepair Powerbond displays the ability to protect and preserve the hair fibres from these extreme chemical processes. Granrepair Powerbond was easily incorporated during the formulation of the
September 2018 1000.00 10000.00
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