CMC对石墨-H_2O分散液稳定性的影响

Effect of CMC on Stability of Graphite-H_2O Dispersion

选用羧甲基纤维素钠(CMC)作为分散剂,制备了稳定性较好的石墨-H2O分散液。通过测定石墨-H2O分散液的吸光度和Zeta电位,探讨了不同CMC添加量、pH值、球磨时间对石墨-H2O分散液稳定性的影响,并分析了作用机理。结果表明:以石墨质量为基准,CMC用量大于4.5%时,分散液稳定性较好;该体系中,主要通过静电斥力使石墨粒子保持稳定,Zeta电位绝对值与吸光度有良好的对应关系,Zeta电位绝对值越高,吸光度越大,分散液稳定性越好;pH值对分散液的稳定性影响很大,pH=9～10时,分散液稳定性最好;随着球磨时间的增大,石墨粒径越来越小,球磨180min时,得到平均粒径为2.284μm的石墨-H2O分散液;石墨-H2O分散液的粒径分布及粘度曲线表明,加入CMC使石墨粒子在水中达到良好的分散。

CMC was chosen as dispersant, and graphite-H2O dispersion with high stability was prepared. Some potential factors related to the stability of dispersion such as CMC content, pH value, and ball milling time were studied by testing the Zeta potential and absorbency, and the mechanism was also analyzed. It was found that the good stability of dispersion was achieved under the condition of adding more than 4.5% （wt） of CMC based on the weight of graphite, and there is a corresponding relation between absolute value of Zeta potential and absorbency. It was indicated that pH value has a significant effect on the stability of the dispersion, and the better stability of the dispersion could be obtained when pH value ranging from 9 to 10. The electrostatic repulsion supplied by CMC dispersed the graphite particles in this system. It was observed that the particles size of the dispersion become smaller with the increasing of ball milling time, and the mean particle diameter of the dispersion is 2. 284μm under the condition of 180min ball milling. Viscosity curve and particles size distribution of graphite-H2O dispersion showed the graphite particles reach a fine dispersion degree in water.