Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil.
J Cosmet Dermatol. 2020 Feb;19(2):508-513. doi: 10.1111/jocd.13006. Epub 2019 Jun 26.
Acid straightener products are widely used, and it can cause changes in the hair shaft properties. The pH value of these products established by ANVISA (Brazil's National Health Surveillance Agency) as secure is above 2.0. However, the industries are interested in working at lower pH values in order to increase the straightening effect. Unfortunately, there are a lot of products in the market with pH value under the permitted.
Analyze two different pH values (1.0 and 2.0) of acid straightener formulation and the influence of this difference in the hair shaft properties. In order to provide information to professionals as cosmetologists, dermatologists, and hairdressers.
Combing and colorimetric analyses, tensile strength, differential scanning calorimetry (DSC), environmental scanning electron microscope (ESEM), and tryptophan content.
The tresses treated at pH 1.0 had a better result in the straightening capacity, improving the combing test in 59.4%, while those at pH 2.0, only in 33.0% compared with virgin hair. However, the tensile strength, at pH 1.0 decreased by 16.0% and 9.0% to the pH 2.0. In addition, the tryptophan content was lower in the tresses treated with formulation at pH 1.0. The DSC analysis showed impairment in the straightened tresses. The images by ESEM, indicated a possible formation of a film around the fiber.
It was possible to conclude that the pH value interferes in the hair shaft properties. Tresses treated with pH 1.0 had more modifications than tresses treated with pH 2.0.
酸直发产品应用广泛，会引起毛发性质改变。巴西国家卫生监督局（ANVISA）规定安全的产品 pH 值应高于 2.0。但为了提高直发效果，产业界有降低 pH 值的兴趣。遗憾的是，市场上有很多产品的 pH 值低于规定。
分析酸直发制剂两种不同 pH 值（1.0 和 2.0）以及这种差异对毛发性质的影响。为美容师、皮肤科医生和美发师等专业人员提供信息。
梳理和比色分析、拉伸强度、差示扫描量热法（DSC）、环境扫描电子显微镜（ESEM）和色氨酸含量。
pH 值为 1.0 的发束拉直效果更好，梳理试验改善 59.4%，而 pH 值为 2.0 的发束仅改善 33.0%，与未处理头发相比。然而，与 pH 值 2.0 相比，pH 值 1.0 的拉伸强度降低了 16.0%和 9.0%。此外，用 pH 值 1.0 的制剂处理的发束色氨酸含量较低。DSC 分析显示拉直发束受损。ESEM 的图像表明纤维周围可能形成了一层膜。
pH 值会影响毛发性质，可以得出结论，pH 值 1.0 处理的发束比 pH 值 2.0 处理的发束有更多的修饰。
