Persaud D, Kamath Y K
TRI Princeton, P.O. Box 625, Princeton, NJ 08542, USA.
J Cosmet Sci. 2004;55 Suppl:S65-77.
In this study, we have developed a single hair fiber torsional pendulum method to determine the role of the cuticle and the cortex on torsional properties with respect to fiber cross-sectional area, fiber rigidity, and energy dissipation at 65% RH and in the wet state. Our results demonstrate that in fine diameter fibers with a high cuticle-to-cortex ratio, the cuticula exert a significant effect on the torsional deformation behavior of hair fibers at both normal humidities and in the wet condition. In addition, our data indicate that energy dissipation is confined to fibers with a high cuticle-to-cortex ratio, and the amount of energy dissipated becomes more pronounced with increasing water content. The torsional properties of hair spray-treated fibers suggest that the deposited hair spray film masks the properties of the base fiber and imparts its own dissipative character to the measurement. Since tensile mechanical properties are often used to make claims about the performance of hair care products, we have compared the results obtained from torsional and tensile measurements on over-processed bleached hair fibers conditioned with Polyquaternium-10 and cetyl trimethylammonium bromide (CETAB) to evaluate which method is more advantageous. Our data demonstrate that torsional measurements can distinguish hair care products which reinforce the cuticle from those which affect the cortex, while tensile measurements showed no significant differences.
在本研究中，我们开发了一种单根毛发纤维扭摆法，以确定角质层和皮质层在65%相对湿度及湿态下，相对于纤维横截面积、纤维刚性和能量耗散的扭转性能方面所起的作用。我们的结果表明，在角质层与皮质层比例高的细直径纤维中，角质层在正常湿度和湿态下对毛发纤维的扭转变形行为均有显著影响。此外，我们的数据表明，能量耗散仅限于角质层与皮质层比例高的纤维，并且随着含水量增加，能量耗散量变得更加明显。经头发定型喷雾处理的纤维的扭转性能表明，沉积的头发定型喷雾膜掩盖了基础纤维的性能，并赋予测量其自身的耗散特性。由于拉伸机械性能常被用于宣称护发产品的性能，我们比较了用聚季铵盐-10和十六烷基三甲基溴化铵（CETAB）调理的过度加工漂白毛发纤维的扭转和拉伸测量结果，以评估哪种方法更具优势。我们的数据表明，扭转测量可以区分强化角质层的护发产品和影响皮质层的护发产品，而拉伸测量则没有显著差异。
