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This dissertation involves the study of the growth dynamics of colloidal particles under unequilibrium and irreversibility condition. Firstly, it is of interest to investigate whether the ideal diffusion or reaction-limited aggregation universal behavior can be observed for the initially polydisperse practical system of basic yttrium carbonate as well. The fractal structure of basic yttrium carbonate aggregate cluster was observed using transmission eletron microscopy. The aggregation kinetics of basic yttrium carbonate colloids was studed using dynamic 1ight-scattering techniques. At 1.00mol/l NaCl solution the fast diffusion-limited aggregation behavior was observed with an increase in the aggregate size over time described by a power law. The aggregates are characterized by a fractal dimension D=1.82. The disordered and ramified cluster is consisted of primary colloidal particles and tenuous and more open. These are in good agreement with those observed for other colloidal system such as colloidal gold (1.86), silica (1.85) and polystyrene latex (1.82) in diffusion-limited aggregation from the static and dynamic light scattering by Lin. Therefore ideal diffusion-limited aggregation behavior can be observed in practical polydisperse system as well. Smoluchwski and fractal theories were used to obtain the aggregation rate constant for initially polydisperse system for the first time.
本论文研究胶粒的非平衡不可逆聚集动态学,分为两个部分,第一部分是通过实验研究一个新的初始多分散的碱式碳酸钇胶粒实际体系中,聚集标度性质的普适性,即使用透射电子显微技术观测聚集粒子簇的分形结构,使用动态激光光散射研究碱式碳酸钇胶粒的聚集动力学,胶粒带电而产生静电排斥作用使得碱式碳酸钇胶粒处于稳定状态,当加入电解质NaCl溶液时,碱式碳酸钇胶粒间的Debye-Hückel屏蔽距离缩短,从而降低静电排斥能垒,引起胶粒发生不可逆聚集,加入电解质NaCl的浓度为1.00mol/l时,碱式碳酸钇胶粒进行快速聚集,经历扩散控制聚集机理,形成结构疏松、更为开放的分形聚集粒子簇,其分形维数为1.82,碱式碳酸钇胶粒聚集增长动力学遵循幂函数增长规律,与Lin等使用静态激光光散射和动态激光光散射测量硅胶(1.85)、金胶(1.86)和聚苯乙烯胶乳(1.82)在扩散控制聚集状态形成聚集粒子簇的分形维数值以及粒子簇聚集增长的动力学规律相一致,表明胶粒聚集标度性质的普适性质在初始多分散的实际体系中也是存在的,首次由动态激光光散射的实验数据得到初始多分散胶粒分形粒子簇的聚集速率常数,并且其值与Smoluchowski聚集速率理论预期相符。