Yan Zilin, Wilkinson Sam K, Stitt Edmund H, Marigo Michele
Johnson Matthey Technology Centre, P.O. Box 1, Belasis Avenue, Billingham, Cleveland, TS23 1LB, United Kingdom.
Johnson Matthey Technology Centre, P.O. Box 1, Belasis Avenue, Billingham, Cleveland, TS23 1LB, United Kingdom.
Int J Pharm. 2016 Nov 20;513(1-2):38-48. doi: 10.1016/j.ijpharm.2016.08.065. Epub 2016 Sep 3.
Mixing and segregation in a Freeman FT4 powder rheometer, using binary mixtures with varied particle size ratio and volume fraction, were studied using the Discrete Element Method (DEM). As the blade moves within the particle bed, size induced segregations can occur via a sifting mechanism. A larger particle size ratio and/or a larger volume fraction of large particles lead to a quicker segregation process. A higher particle velocity magnitude can promote the segregation process and the rate for the segregation index increases in the radial direction: from the centre towards the outer layer. In the current DEM simulations, it is shown that the change in flow energy associated with segregation and mixing depends on the choice of frictional input parameters. FT4 is proposed as a potential tool to compare and rank the segregation tendency for particulate materials with distinct differences in flow energy of each component. This is achieved by measuring the flow energy gradient after a number of test cycles for mixing powders with different flow properties. Employing the FT4 dynamic powder characterisation can be advantageous to establish blending performances in an industrial context.
使用离散元法（DEM）研究了在Freeman FT4粉末流变仪中，采用具有不同粒径比和体积分数的二元混合物时的混合与离析情况。当叶片在颗粒床内移动时，尺寸诱导的离析可通过筛分机制发生。较大的粒径比和/或较大体积分数的大颗粒会导致更快的离析过程。较高的颗粒速度大小可促进离析过程，且离析指数的速率在径向方向上增加：从中心向外层。在当前的DEM模拟中，结果表明与离析和混合相关的流动能量变化取决于摩擦输入参数的选择。FT4被提议作为一种潜在工具，用于比较和排序各组分流动能量存在明显差异的颗粒材料的离析倾向。这是通过在对具有不同流动特性的粉末进行多次混合测试循环后测量流动能量梯度来实现的。采用FT4动态粉末表征对于在工业环境中确定混合性能可能是有利的。
