58 HAIR CARE
regarded as an important indicator of the effectiveness of hair styling polymers. Consequently the effectiveness of an aqueous solution of Sodium Polyitaconate was compared with the effectiveness of a styrene sulfonate copolymer, an acrylamide/acrylate copolymer and a polyurethane copolymer. In this study, 1.2 g of an aqueous solution containing polymer at 2% (w/w) was applied to tresses made from wavy European brown hair (30 cm, 5g) and combed through. The tress was then straightened using 10 passes of a commercial straightening iron set to the recommended 200°C, for 10 second per pass. The tresses were allowed to equilibrate at ambient temperature and humidity before being placed in a temperature and humidity controlled cabinet (25°C, 85% RH). Digital photography was used to record the status of the tresses initially and following 24 hours exposure to high humidity. The results of the style retention test are shown in Figure 1. Comparison of the style hold following exposure to high humidity for 24 hours showed that each of the polymers tested had outperformed the control and provided a style retention benefit by substantially preserving the narrow shape of the tress whereas the control tress had broadened and developed a significant amount of frizz. It was difficult to distinguish between the individual polymers tested in this study with each polymer delivering an approximately equal performance.
Heat damage study Thermal hair styling is commonplace among today’s consumers and consequently hair products that offer protection from heat damage are a key component of many hair care product ranges. These products can be used during thermal styling to help prevent cuticle damage such as cracking, breaking and raising of the cuticle edge which would otherwise lead to a rougher hair surface and
100 90 80 70 60 50 Untreated Control Sodium Polyitaconate
Styrene Sulfonate Copolymer
Acrylamide Acrylate Copolymer
Polyurethane Copolymer
Figure 2: Individual hair fibre strength (10 treatment cycles).
increased porosity. If allowed to occur this will create increased friction between the fibres making the hair less manageable and more difficult to comb. Moreover, structural damage will reduce the tensile strength of the hair fibres leading to more breakage. A heat treatment cycle was developed to mimic the way that consumers will use appliances and hair protection products over a period of several months. 1.2 g of an aqueous solution of the polymer at 2% (w/w) was applied to tresses made from wavy European brown hair (30 cm, 5g) and combed through. For the control, water was used in place of the polymer solution. A commercially available straightening iron was used to hot style the tresses at the recommended 200°C. Ten passes of 10 seconds each were made for each cycle. Following each cycle, the tress was allowed to equilibrate at ambient temperature and humidity before being washed. For the wash protocol, the tress was wetted with 40°C water and 0.625 g of a basic shampoo formulation was spread evenly over the tress which was then rubbed gently in a circular motion for 30 seconds. The tress was then rinsed with running 40°C water for 45 seconds. This process was repeated with a further 0.625g of shampoo. Finally the
40000 30000 20000 10000 0 Untreated Figure 3: SEM individual fibre images (20 treatment cycles). PERSONAL CARE EUROPE Control Sodium Polyitaconate Figure 4: Comb resistance (10 treatment cycles). September 2018
Styrene Sulfonate Copolymer
tress was allowed to dry at ambient conditions until the next cycle. In order to analyse the tensile strength of
the hair tresses following the heat cycle, individual fibres were removed from the tress and the load to breaking point was determined using a texture analyser. To measure comb resistance, a texture analyser fitted with a combing device was used. The comb was cycled through the tress 5 times while the analyser measured the force exerted on the comb. The average load was calculated for comb cycles 2 to 5 and the area under the graph of comb load versus the distance traveled was calculated. The results of the tensile strength test
are shown in Figure 2. The results are average values of repeat experiments quoted with the standard error of the mean. The data represented are those for untreated hair fibers (untreated); hair fibres from tresses subjected to 10 cycles of the heat treatment protocol (control); and fibres from tresses that had been treated with polymer solutions before being subjected to the heat treatment protocol. Fibres from the tresses treated with sodium polyitaconate solution gave similar results to the untreated fibres suggesting
Load to Breaking Point (g)
Total Comb Load (
g.cm)
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