【作者】 顾志明；

【导师】 陈舒林； 李凤生； 宋洪昌；

【作者基本信息】 南京理工大学 ， 材料学， 2002， 博士

【摘要】 本文根据胶体的分散稳定理论，研究了超细重质碳酸钙水分散体系的稳定机理，旨在为实际应用中的稳定的超细重质碳酸钙水分散体系提供理论指导和操作条件。同时，从DLVO理论的基础方面出发，利用热力学、静电学、数学等方面知识，研究了粒子双电层的自由能、相互作用和电荷分布，其目的是力图发现DLVO理论中可能遗漏的有关胶体粒子相互作用的一些重要性质或某些方面的不足之处。其主要内容如下： 1．利用沉降体积、粘度测定、Zeta电位测定等手段，根据胶体的分散稳定理论，研究了聚丙烯酸钠、六偏磷酸钠、十二烷基苯磺酸钠对10wt％固含量超细重质碳酸钙水分散体系的稳定机理，发现浆料稳定性强烈地受分散剂的用量和pH值的影响；分散剂用量并非越多越好，有一最佳值。通过比较选择聚丙烯酸钠为超细重质碳酸钙的最佳分散剂。 2．实验结果表明以聚丙烯酸钠为分散剂可制得固含量较高的超细重质碳酸钙水分散体系。以聚丙烯酸钠为分散剂，随粉体固含量的不同，分散剂各有其最佳的用量范围。随着固含量的提高，分散剂的最佳用量随之增加。 3．在实际的粒子双电层中，介电常数ε应该是有变化的。利用静电学原理，通过直接分析得到了介电常数非均匀情况下的粒子双电层力表达式。 4．结合实验测试结果和理论计算结果，通过数学分析探讨了平板双电层中的电荷分布描述问题，考虑介电常数的变化情况将更好地表示实际的双电层电荷分布。 5．利用介电常数非均匀情况下的浓分散体系中的粒子双电层力表达式，发现高表面电荷能够引起胶体粒子间产生长距离静电吸引作用。 6．利用静电学原理、热力学第二定律等，分别分析了转移法和放电法获得双电层自由能的推导过程，发现转移法和放电法均不适合确定双电层自由能。 7．两个相同平板的双电层交叠造成的作用力，传统的直接计算法给理解板的具体受力情况带来一些困难。利用静电学原理，直接分析了板的具体受力情况，得到了作用在板上的双电层力表达式。更多还原

【Abstract】 Based on colloidal dispersion stabilization theory, the mechanism of stabilization of ultrafine ground calcium carbonate aqueous dispersions is investigated in the dissertation. The purpose of the research is to provide theoretical guide and operation conditions for stabilized ultrafine ground calcium carbonate aqueous dispersions in practical applications. Starting with the foundations of DLVO theory, free energy of electrical double layers, electrical-double-layer interaction, and charge distribution in electrical double layers are investigated by using the relevant knowledge in thermodynamics, electrostatics, and mathematics. It is expected that the research tries hard to find some omitted properties relevant to colloidal interactions or shortcomings in DLVO theory. The contents of this dissertation are as follows:1 . Based on colloidal dispersion stabilization theory, by means of sedimentation volume, viscosity measurement, Zeta potential measurement etc, the mechanism of stabilization of 10wt% ultrafine ground calcium carbonate aqueous dispersions are investigated by employing polyacrylate sodium, sodium hexametaphosphate, and sodium dodecylbenzenesulfonate as dispersants. The stabilities of slurries are intensely influenced by the contents of dispersants and pH value in slurries; the higher contents of the dispersant do not the better dispersion effects, the contents of the dispersant have optimum contents. By comparison, polyacrylate sodium is an optimum dispersant for ultrafine ground calcium carbonate aqueous dispersions.2. The experimental results demonstrate that high-solid-content ultrafine ground calcium carbonate aqueous dispersions can be obtained by employing polyacrylate sodium as dispersant. The contents of polyacrylate sodium as dispersant vary with solid content, and have various optimum content ranges. The optimum contents of the dispersant rise with solid content.3. In the real electrical double layer of particles, dielectric constant s can be nonuniform. Based on the principles of electrostatics, the double-layerforce expression on a particle is obtained by direct analysis.4 . Combined with experimental results and results of theoretical calculation, by means of mathematical analysis, the charge distribution in a flat double layer is investigated. The generalized Poisson-Boltzmann equation where nonuniform dielectric constant is taken into account would better describe the real charge distribution in a double layer.5. Combined with the double-layer force expression on a particle in concentrated dispersions in the case of nonuniform dielectric constant, long-range electrostatic attractions between colloidal particles can be accounted for high surface charge density.6 . Based on the principles of electrostatics, the second law of thermodynamics, the derivation processes of the free energy of the double layer by the transferring method and the discharging method are analyzed. The transferring method and the discharging method are not suitable to determine the free energy of the double layer.7. The traditional direct calculation method of the double layer interaction force on two similar plates brings some difficulties for understanding of specific forces on plates. Based on the principles of electrostatics, the specific forces on plates are directly analyzed, and the expressions of the double layer forces on plates are obtained.更多还原