Luukkonen P, Schaefer T, Podczeck F, Newton M, Hellén L, Yliruusi J
Pharmaceutical Technology Division, Department of Pharmacy, P.O. Box 56, 00014 University of, Helsinki, Finland.
Eur J Pharm Sci. 2001 May;13(2):143-9. doi: 10.1016/s0928-0987(00)00197-4.
A powder rheometer has been used to study the properties of wet powder masses and the results have been compared to the mixer torque rheometer (MTR). Two different microcrystalline cellulose (MCC) grades (Avicel and Emcocel) and silicified microcrystalline cellulose (SMCC, Prosolv) were used as model powders. The wet massing behaviour of one material (Prosolv) was studied by the powder rheometer using liquid addition experiments, while the rheological properties of wet granules were studied using both the powder rheometer and the MTR. In water addition measurements the torque behaved in a similar way to MTR measurements and the maximum value of ZTL (zero torque limit) was achieved at the capillary state of wet mass. The wet granules exhibited different behaviour in the powder rheometer and the MTR experiments, which indicates that these rheometers involve different shear forces or they measure different properties of the wet granules. Emcocel wet masses achieved the capillary state at lower liquid amount than Avicel and Prosolv masses, which indicates that Emcocel is not able to hold as much water in the internal structure as Avicel and Prosolv. The powder rheometer proved to be a sensitive piece of equipment, which can be used to study both dry and wet powder masses. It was able to distinguish wet granules from wet powder masses after liquid addition, whereas the MTR could not. However, before the powder rheometer can be properly utilised in wet powder mass studies, the problem of torque overload requires resolution.
已使用粉末流变仪研究湿粉末物料的特性，并将结果与混合器扭矩流变仪（MTR）进行了比较。使用两种不同等级的微晶纤维素（MCC，微晶纤维素和埃姆科塞尔）和硅化微晶纤维素（SMCC，普罗索夫）作为模型粉末。通过粉末流变仪使用液体添加实验研究了一种材料（普罗索夫）的湿法制粒行为，同时使用粉末流变仪和MTR研究了湿颗粒的流变特性。在加水测量中，扭矩的表现与MTR测量相似，并且在湿物料的毛细管状态下达到了ZTL（零扭矩极限）的最大值。在粉末流变仪和MTR实验中，湿颗粒表现出不同的行为，这表明这些流变仪涉及不同的剪切力，或者它们测量的是湿颗粒的不同特性。埃姆科塞尔湿物料在比微晶纤维素和普罗索夫物料更低的液体量下达到毛细管状态，这表明埃姆科塞尔在内部结构中保留的水分不如微晶纤维素和普罗索夫多。事实证明，粉末流变仪是一种灵敏的设备，可用于研究干粉和湿粉物料。添加液体后，它能够区分湿颗粒和湿粉末物料，而MTR则不能。然而，在粉末流变仪能够在湿粉末物料研究中得到妥善利用之前，扭矩过载问题需要解决。
