Department of Chemistry, University of Reading, Whiteknights Reading UK.
Int J Cosmet Sci. 1997 Aug;19(4):173-91. doi: 10.1046/j.1467-2494.1997.171713.x.
Using silicone copolymers in personal care products can improve the aesthetic performance of formulations. During their manufacture, distribution and topical application they are subject to various mechanical stresses. In this study rheology was used to measure their effects. A number of water in silicone (w/Si) emulsions were prepared in which the oil phase consisted of cyclomethicone. The surfactant used was a branched type silicone copolymer. Both viscoelastic and viscometry measurement were performed on model systems and on commercial products. Experimental data were obtained using a Bohlin rheometer. The measurements were taken applying shear rates in the range of 0.46-58 l s-1 and for the strain sweep frequencies of 0.1 Hz, 1 Hz and 10 Hz were applied. Oscillation tests were performed in the 0.1 Hz to 10 Hz range. All measurements were taken at 35deg;C, representing the approximate temperature encountered during topical application. The effect of surfactant concentration on viscoelastic properties was examined. It was shown that with increasing surfactant concentration the elastic moduli G' and the viscous moduli G" increased. Furthermore, the emulsions showed a transition from a predominantly elastic to a predominantly viscous response as the surfactant concentration increased. The effect of varying the water phase volume fraction on viscometry and viscoelastic measurements was also examined. With increasing water phase volume fraction the viscosity of the emulsions, as well as the yield stress, increased. The Cross and Sisko models were applied. From the Dougherty and Krieger equation phieff was calculated. It was found the the data derived from the Sisko model gave more reliable results. Results obtained from commercial samples showed a high proportion of elasticity; oscillation tests and viscometry experiments suggested that tumbling had the biggest impact on the theological profiles; viscosity, eta, shear stress, sigma, elastic module, G', and dynamic viscosity, eta', dropped to a minimum in these samples. Results from the two commercial samples were compared and it was observed that, although both were w/o emulsions, different rheological behaviour could be observed.
在个人护理产品中使用硅酮共聚物可以改善配方的美观性能。在制造、分配和局部应用过程中，它们会受到各种机械应力的影响。本研究使用流变学来测量它们的影响。制备了许多水在硅酮（w/Si）乳液，其中油相由环甲硅氧烷组成。所用的表面活性剂是一种支化硅酮共聚物。在模型体系和商业产品上都进行了粘弹性和流变测量。使用 Bohlin 流变仪获得实验数据。测量是在剪切速率为 0.46-58 l s-1 的范围内进行的，对于应变扫描频率，应用了 0.1 Hz、1 Hz 和 10 Hz。在 0.1 Hz 至 10 Hz 的范围内进行了振荡测试。所有测量均在 35°C 下进行，这是局部应用过程中遇到的近似温度。研究了表面活性剂浓度对粘弹性的影响。结果表明，随着表面活性剂浓度的增加，弹性模量 G'和粘性模量 G"增加。此外，随着表面活性剂浓度的增加，乳液表现出从主要弹性到主要粘性响应的转变。还研究了改变水相体积分数对流变和粘弹性测量的影响。随着水相体积分数的增加，乳液的粘度以及屈服应力增加。应用了 Cross 和 Sisko 模型。从 Dougherty 和 Krieger 方程计算出了 phieff。结果表明，Sisko 模型得出的数据更可靠。商业样品的结果表明具有高弹性比例；振荡测试和流变实验表明，翻滚对流变学曲线的影响最大；在这些样品中，粘度 η、剪切应力 σ、弹性模量 G'和动态粘度 η'降至最低。比较了两个商业样品的结果，观察到尽管两者都是 w/o 乳液，但可以观察到不同的流变行为。
