School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, United States.
Department of Chemical & Biochemical Engineering, Rutgers, The State University of New Jersey, United States.
Int J Pharm. 2018 Dec 1;552(1-2):56-66. doi: 10.1016/j.ijpharm.2018.09.036. Epub 2018 Sep 18.
Single drop impact of liquid on a static powder bed was studied to investigate the granule formation mechanism, droplet penetration time, as well as the characterization of granules (morphology, surface structure and internal structure). Water was used as the liquid and two pharmaceutical powders, microcrystalline cellulose (MCC) and acetaminophen (APAP), were mixed to make heterogeneous powder beds. The complete drop impact and penetration was recorded by a high speed camera. Two granule formation mechanisms that have been identified previously occurred: Spreading and Tunneling. Spreading occurred for mixtures with an APAP amount of less than 20%, while Tunneling started to occur when the APAP amount increased above 20%. With an increase of APAP concentration, the mean particle size decreased, drop penetration time increased, and the granules formed became smaller in size, which was in good agreement with previous literature. The granule morphology, surface structure, and internal structure were characterized by a prism method with image analysis, scanning electron microscopy (SEM), and X-ray microtomography, respectively. The Spreading mechanism produced flat disks with a porous internal structure, while the Tunneling mechanism produced round granules with a dense internal structure. There is a clear trend of decreasing porosity and increasing roundness of granules made from heterogeneous mixtures within the transition from Spreading to Tunneling. It is believed that the mean particle size of the powder bed and the powder-liquid contact angle are the predominant factors in influencing the formation mechanism, drop penetration time, and granule properties.
研究了液滴对静态粉末床的单次冲击，以研究颗粒形成机制、液滴穿透时间以及颗粒的特性（形态、表面结构和内部结构）。水被用作液体，两种药用粉末，微晶纤维素（MCC）和对乙酰氨基酚（APAP），被混合以形成多相粉末床。高速摄像机记录了完整的液滴冲击和穿透过程。已经确定了两种先前存在的颗粒形成机制：扩展和隧道。当 APAP 含量低于 20%时，发生扩展；当 APAP 含量增加到 20%以上时，隧道开始发生。随着 APAP 浓度的增加，平均粒径减小，液滴穿透时间增加，形成的颗粒尺寸减小，这与以前的文献一致。颗粒形态、表面结构和内部结构分别通过棱镜法与图像分析、扫描电子显微镜（SEM）和 X 射线微断层扫描进行了表征。扩展机制产生具有多孔内部结构的扁平盘，而隧道机制产生具有致密内部结构的圆形颗粒。在从扩展到隧道的转变过程中，多相混合物中颗粒的孔隙率降低和圆度增加的趋势明显。据信，粉末床的平均粒径和粉末-液体接触角是影响形成机制、液滴穿透时间和颗粒性能的主要因素。
