黄原胶和瓜尔胶混合溶液及其硼砂交联体系的流变性能

Rheological Properties of Xanthan Gum/Guar Gum Mixed Solution and Its Borax-Crosslinked System

本文研究了黄原胶(XG)和瓜尔胶(GG)的混合溶液及其硼砂(B)交联体系的流变性,考察了XG/GG间的“协同增效作用”以及溶液组成、pH和电解质(NaCl和CaCl 2)对其流变性的影响。结果表明,所有溶液体系均为假塑型流体,其流变曲线可用Herschel-Bulkley和Casson模型描述。XG和GG复配具有明显的“协同增粘效应”,在XG占两聚合物的质量分数w(XG)为20%和90%时协同增粘效应最强,其“协同增粘率”(R m)分别约为42%和34%。硼砂(B)可交联XG/GG混合溶液,其交联增粘效果随w(XG)的减小和硼砂质量浓度ρ(B)的增大而增大;在w(XG)=50%和ρ(B)=1.00 g/L时,“交联增粘率”可达85%。在所研究的pH值范围(6.2~10.0)内,XG/GG混合溶液的流变性基本无变化,而XG/GG/B交联体系(w(XG)=50%和ρ(B)=0.75~1.00 g/L)的表观粘度随pH值增大先升高后降低,pH=9.0时出现最大值,交联增粘率达107%。电解质可使XG/GG/B交联溶液(w(XG)=10%和ρ(B)=0.50 g/L)体系的粘度大幅下降,且CaCl 2的影响明显高于NaCl,表明交联结构的耐盐能力较差。这些结果加深了对XG/GG混合溶液流变性的认识,可为其实际应用(如在强化采油中的应用)提供依据。

The rheological properties of xanthan(XG)/guar gum(GG)mixed solutions and their borax-crosslinked systems were investigated at a total solution concentration of 2.00 g/L.The synergistic interaction viscosification efficiency between XG and GG as well as the influence of solution composition,pH,and electrolytes(NaCl and CaCl 2)on the rheological properties were discussed.Under the studied conditions,all solution systems including pure XG,pure GG,and mixed XG/GG solutions as well as their borax-crosslinked systems behave as pseudoplastic fluids,and the rheological curves can be described by the Herschel-Bulkley and Casson models.The mixing of XG and GG exhibits a significant“synergistic viscosification effect”.When the mass fraction of XG in the two polymers(w(XG))is 20%and 90%,maximum values of the synergistic viscosification rate(R m)are observed,which are 42%and 34%,respectively.The XG/GG mixed solutions can be crosslinked by borax,and the crosslinking effect is enhanced with a decrease in w(XG)or an increase in borax mass concentration(ρ(B)).At w(XG)=50%andρ(B)=1.00 g/L,the crosslinking viscosification rate(R)is up to 85%.In the studied pH range(6.2~10.0),there is no obvious change in the rheological properties for XG/GG mixed solutions,while for the borax-crosslinked systems(w(XG)=50%andρ(B)=0.75~1.00 g/L),the apparent viscosity initially increases and then decreases,showing a maximum value at pH=9.0,and the corresponding R is up to^107%.The addition of electrolytes(NaCl and CaCl 2)leads to a significant decrease in the viscosity for the crosslinked XG/GG/B solution(w(XG)=10%andρ(B)=0.50 g/L),and the influence of CaCl 2 is more obvious than that of NaCl.These results may deepen the understanding of rheological behavior of XG/GG mixed solutions and provide important information for their practical applications such as in the enhanced oil recovery.