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磁粉在液体介质中的分散过程,由四个不同阶段组成:(1)磁粉的润湿;(2)机械搅拌把磁粉解聚成更小的粒团;(3)小而“聚集”的粒团被密实;(4)赶去磁粉颗粒表面的空气,粒子稳定化,以避免絮凝。粒团的密实是磁性颜料分散过程中非常重要的阶段.非磁性颜料的分散过程也存在粒团密实现象。用汞孔隙仪测定粒团的平均有效粒子密度,可以研究和观察密实现象。在高速砂磨机中分散颜料, 密实所遵循的动力学过程,可以用Int(时间的对数)的线性关系来描述,解聚过程幻前阶段,其速率也与Int成线性关系.但与密实过程相比,速率很快就减慢下来,这些实验表明,解聚和密实是性质不同的两个阶段。测出分散过程的流动曲线,由流动曲线导出体系的流变特性,这些流变特性,仅仅用颜料体积浓度无法解释,而大多数粘度方程仅适用于中等浓度的颜料分散系,Mooney方程虽然考虑了粒子尺寸的影响,但也无法对实验数据作出适当的解释。在粘度方程中,如果考虑粒子尺寸的影响,引入有关粒子尺寸的变量。那么由流动曲线推导出流变性质的变化,就容易理解了,在分析流动数据时,颜料的有效体积和粒子尺寸具有同等的重要性。应用流动曲线分析,可以帮助理解和选择适宜的无机颜料的分散工艺。
Dispersion of magnetic powder in a liquid medium consists of four distinct phases: (1) wetting of the magnetic powder; (2) mechanical agitation to deagglomerate the magnetic powder into smaller pellets; (3) small, “aggregated” Dense; (4) rushed to the surface of the magnetic particle particles, particle stabilization, to avoid flocculation. The compactness of the pellets is a very important stage in the dispersion process of the magnetic pigments.Dispersion of the non-magnetic pigments also has the phenomenon of the compactness of the pellets. The determination of the average effective particle size of the pellets by mercury porosimetry can be used to study and observe the compactness. The kinetic process followed by dispersing the pigment in a high-speed sand mill and compacting can be described by the linear relationship of Int (logarithm of time), the rate of which is also linear with Int. Compared with the dense process, the rate slowed down very quickly. These experiments show that depolymerization and compacting are two phases of different nature. The flow curves of the dispersion process are measured, and the rheological properties of the system are derived from the flow curves. These rheological properties can not be explained by the pigment volume concentration alone. Most of the viscosity equations are only suitable for medium concentration pigment dispersion systems. Although the Mooney equation The effect of particle size, but also the experimental data can not be properly explained. In the viscosity equation, variables related to particle size are introduced if particle size is taken into account. Then it is easy to understand the change in the rheological properties derived from the flow curve, and the effective volume of the pigment and particle size are of equal importance in the analysis of the flow data. Application of flow curve analysis, can help understand and select the appropriate inorganic pigment dispersion process.