In this paper, the influence of clobetasol propionate and sodium dodecyl sulfate on the viscoelastic modules and gelation transition of aqueous solutions of poloxamer 407 are investigated experimentally. The influence of the polymer volume fraction is also examined. The experimental investigations are carried out with eight different samples of solutions. Four of them are free of additives varying just on macromolecule volume fraction. The other four samples are produced from the previous ones by addition of clobetasol and a surfactant (sodium dodecyl sulfate) in a volume fraction compatible with commercial applications. All samples are sheared in a high-performance rheometer of parallel disks with an automatic control of gap and temperature. The first set of tests are carried out under the condition of steady shear. From these tests, we obtain results for the apparent viscosity of the solutions of shear rate for two different temperatures, 6 ∘ C and 36 ∘ C. While a shear-thinning behavior is verified for the temperature of 36 ∘ C, the viscosity is observed to have a non-shear rate dependence at 6 ∘ C for all samples. The second tests deal with non-isotherm trials under a regime of small amplitude oscillatory shear, in a temperature range from 3.5 to 50 ∘ C. The viscoelastic moduli of storage and loss of energy are obtained as a function of the temperature for fixed values of frequency and angular deflection. The gelation transition of the polymer solution is characterized as a sudden change in the viscoelastic modulus. This interesting finding is directly associated with microstructure transitions induced by increase of the temperature. We show results of the temperature of micellization and the gelation temperature as a function of the polymer volume fraction for a suspension in the absence of additives and with a certain volume fraction of SDS (surfactant) and clobetasol propionate. The presence of additives reinforces the link of micelles making the structure more stable and resistant to breakup. The effect of SDS or clobetasol propionate on gelation is seen to be very important, and there is a lack of systematic research about additives. We also present a result for the shear elastic modulus of the solution as a function of the polymer volume fraction for 6 ∘ C. This shows that the micelles-like chain formation at a given temperature leads to a solid characteristic of the polymer that can be interpreted as a yield stress even at low temperatures. The presence of SDS and clobetasol propionate produces new rheological response of the poloxamer.

中文翻译：

---

某些添加剂存在下热敏弹性液体剪切流的流变响应

本文通过实验研究了丙酸氯倍他索和十二烷基硫酸钠对泊洛沙姆407水溶液粘弹性模量和胶凝转变的影响。还检查了聚合物体积分数的影响。实验研究是用八种不同的溶液样品进行的。其中四个不含仅因大分子体积分数而异的添加剂。其他四个样品是通过添加体积分数与商业应用相容的氯倍他索和表面活性剂（十二烷基硫酸钠）从前面的样品制备的。所有样品均在具有间隙和温度自动控制的平行圆盘的高性能流变仪中进行剪切。第一组试验在稳定剪切条件下进行。从这些测试中，我们获得了两种不同温度下剪切速率溶液的表观粘度结果，6 ∘ C 和 36 ∘ C。虽然在 36 ∘ C 的温度下验证了剪切稀化行为，但观察到粘度具有非-所有样品在 6 ∘ C 处的剪切率依赖性。第二个测试涉及在小振幅振荡剪切机制下的非等温线试验，温度范围为 3.5 到 50 ∘ C。存储和能量损失的粘弹性模量作为固定值的温度的函数获得频率和角偏转。聚合物溶液的凝胶化转变以粘弹性模量的突然变化为特征。这一有趣的发现与温度升高引起的微观结构转变直接相关。我们展示了胶束化温度和凝胶温度的结果，作为悬浮液中聚合物体积分数的函数，在没有添加剂和一定体积分数的 SDS（表面活性剂）和丙酸氯倍他索的情况下。添加剂的存在加强了胶束的连接，使结构更加稳定和抗破裂。SDS或丙酸氯倍他索对凝胶化的影响被认为是非常重要的，缺乏对添加剂的系统研究。我们还提供了溶液的剪切弹性模量作为 6 ∘ C 的聚合物体积分数的函数的结果。这表明在给定温度下胶束状链的形成导致聚合物的固体特性，可以即使在低温下也被解释为屈服应力。