Abstract

A thorough rheology characterization of aqueous solutions of diutan gum, in different concentration (2000, 4300, 6000, and 8000 ppm) and temperatures (20, 40 and 60 °C), was conduct in order to determine the following rheological properties: viscosity; storage modulus; loss modulus; complex modulus and complex viscosity. Tests of flow curve, structural recovery, temperature sweep, creep and recovery, frequency sweep and stress sweep were performed. Rheological models were used to fit the experimental data. The aqueous solutions of diutan gum show pseudoplastic and viscoelastic behavior. The Power-Law and the Cross models fit very well the pseudoplastic behavior of aqueous solutions of diutan gum. The storage modulus (G′), in the case of 6000 and 8000 ppm, show larger values compared to loss modulus (G″), indicating a gel behavior for this diutan gum aqueous solutions, in the angular velocities investigated (0.1 to 10 rad/s). For the aqueous solution of diutan gum with 4300 ppm, there is a crossover of the curves of G′ and G″, being G′>G″ for angular velocities greater than 1 rad/s. The exponential model of three parameters fits very well the data of the curves G′ and Gʺ as a function of the angular velocity. The Power Law model fits very well the data of the complex viscosity as a function of the angular velocity. The aqueous solution of diutan gum shows good thermal stability. The study of rheology of aqueous solutions of diutan gum can contribute to better understanding the flow behavior of these biopolymers with many applications.

摘要

对不同浓度（2000、4300、6000 和 8000 ppm）和温度（20、40 和 60 °C）的 diutan 胶水溶液进行彻底的流变学表征，以确定以下流变学特性：粘度；储能模量；损耗模量；复数模量和复数粘度。进行了流动曲线、结构恢复、温度扫描、蠕变和恢复、频率扫描和应力扫描测试。流变模型用于拟合实验数据。diutan胶的水溶液表现出假塑性和粘弹性行为。Power-Law 和 Cross 模型非常适合 diutan 胶水溶液的假塑性行为。储能模量 ( G' )，在 6000 和 8000 ppm 的情况下，与损耗模量 (G″ )，表明在所研究的角速度（0.1 至 10 rad/s）下，该 diutan 胶水溶液的凝胶行为。对于 4300 ppm 的 diutan 胶水溶液，G'和G"的曲线存在交叉，对于大于 1 rad/s 的角速度，G' > G"。的三个参数拟合指数模型很好的曲线的数据G'和G"作为角速度的函数。幂律模型非常适合作为角速度函数的复粘度数据。diutan胶的水溶液表现出良好的热稳定性。研究 diutan 胶水溶液的流变学有助于更好地了解这些生物聚合物在许多应用中的流动行为。