黄原胶溶液及其冻胶的流变特性研究

RHEOLOGICAL PROPERTIES OF XANTHAN GUM SOLUTION AND ITS GEL

为拓宽黄原胶(XG)的应用范围,采用一种有机锆交联剂ZW35对黄原胶溶液进行交联,形成黄原胶冻胶。对黄原胶溶液及其冻胶的交联比、剪切变稀性、粘弹性、触变性以及耐温耐剪切性能进行了研究。结果表明,0.2%XG溶液的表观黏度为17.5mPa·s,随着交联剂用量的增加,黄原胶冻胶的表观黏度先增加后降低,在交联剂用量为0.4%时,表观黏度达到较大值200.4mPa·s。黄原胶冻胶的弹性模量G′、黏性模量G″和触变环面积均比黄原胶溶液有显著的提高,表明黄原胶冻胶的网络结构强度得到增强。0.2%XG溶液在30℃的表观黏度为17.5mPa·s,而黄原胶冻胶(0.2%XG+0.4%ZW35)在80℃、170s^(-1)下剪切90min后的保留黏度仍有82.6mPa·s,耐温耐剪切性得到提高。黄原胶溶液及其形成的黄原胶冻胶均呈现出剪切变稀特性,其流动曲线均可采用非线性共转Jeffreys本构方程进行表征,各体系的模拟值与实验值吻合良好。

In order to improve the basic performance of xanthan gum and widen its application, the xanthan gum （XG） solution was crosslinked by organic zirconium crosslinking agent ZW35 to form stable gels. The rheological properties （shear thinning, viscoelasticity, thixotropy） and basic properties （crosslinking ratio, temperature and shear resistance） of XG solution and XG gel were studied. The results showed that the apparent viscosity of XG gel can firstly increase and then decrease with the increasing amount of the crosslinking agent. The apparent viscosity of 0.2%XG solution was 17.5 mPa · s and the apparent viscosity of 0.2%XG gel was 200.4 mPa · s when the content of crosslinking agent was 0.4%. The storage modulus G＇ and the loss modulus G＂ of XG gels were greater than those of XG solutions, and viscoelastic and thixotropic properties were more significant in XG gels. At 80 ℃ ,XG gel （0.2% XG＋0.4% ZW35） was sheared at 170 s-1 for 90 rain, the reserved viscosity was 82.6 mPa · s, but the apparent viscosity of 0.2% XG solution at 30 ℃ was only 17.5 mPa · s. Nonlinear co-rotational Jeffreys model could be applied to describe the flow curve of XG solutions and XG gels correctly and the simulated values are in good agreement with the experimental data.