微细鳞片石墨分散性

Dispersion of Ultrafine Graphite

采用沉降法研究了微细鳞片石墨在水介质中的分散行为,考察了12种药剂对微细鳞片石墨的分散效果,通过测试加入分散剂前、后颗粒表面Zeta电位、悬浮液粘度的变化及颗粒间相互作用能的计算,研究了分散剂的作用机理。研究结果表明:传统表面活性剂对微细鳞片石墨分散效果不佳,高分子化合物羧甲基纤维素钠和聚丙烯酸钠是微细鳞片石墨的良好分散剂,加入分散剂使颗粒表面Zeta电位绝对值变大,提高了悬浮液的稳定性,降低了体系的粘度,分散剂的最佳质量浓度为500mg/L,合适的pH值为8.5～10.5;疏水性石墨在水介质中的分散行为不符合经典DLVO理论,颗粒表面疏水化作用对其分散和聚团起主导作用,分散剂通过增大静电斥力和空间位阻起作用。

The dispersion behavior of ultrafine graphite in aqueous system was investigated by the sedimentation test. The dispersion effect of 12 kinds of dispersants were studied. By testing the changes of Zeta potential and the viscosity of suspensions with the addition of dispersants, the dispersion mechanism of dispersants was discussed by the calculation of the interaction energies between particles. The results show that traditional surfactants have poor performance on the stability of dispersion, but carboxymethylcellulose and polypropylene acid sodium are the efficient dispersants of graphite. The addition of dispersants can enlarge the absolute value of Zeta potential, increase the stability and decrease the viscosity of the dispersion. The optimum addition of dispersant is 500 mg/L and the suitable pH value is 8.510.5. The calculation results show that the dispersion of hydrophobic graphite does not conform to the DLVO theory. The hydrophobic interaction on the surface of particles controls the dispersion and coagulation of particles and the main effect of dispersants is to increase the electrostatic force and the interspace resistance.