Experimental investigations for the effect of fine powders on size-induced segregation in binary granular mixtures

Particle size segregation in granular pipe flow

The flow of granular material through pipes is characterized by significant variations in solid fraction (density waves) along the pipe. Previously, it has been shown that this intermittent flow behavior can be mitigated by adding a texture to the pipe's inner wall. This work shows that adding surface roughness can lead to particle size segregation as a side effect in bidisperse systems. Using particle simulations, we characterize the parameter ranges in which segregation occurs.

Fabrication of Highly Compacted Green Body Using Multi-Sized Al Powder under a Centrifugal Force

This study investigates the application of centrifugal force for the compaction of metal powder. Previous studies using the centrifugal force for manufacturing the green bodies were focused on fine powders with narrow particle size distribution or binary mixtures. This study explores the particle packing of multi-sized powder. Aluminum alloy powder with a particle size less than 100 µm and polymer binder were admixed and compacted in the centrifugal casting with ranging magnitudes of centripetal acceleration. Three different centrifugal forces were tested: 700, 1800, and 3700 G. The microstructure of the green bodies was then observed on the SEM micrographs. The obtained green bodies had high packing densities ranging from 62 to 69%. The packing density and median particle size increase at the positions further away from the center of rotation of the centrifuge with an increase of centrifugal force. The effect of centrifugal force on the segregation of particles was investigated through the quasi-binary segregation index. The segregation phenomena was not observed at 700 G, but clear particle segregation was found at higher centrifugal forces. The increase of the centrifugal force resulted in higher segregation with finer particles moving to the inner part of the spinning mold, with a significant change in the size of particles located closer to the center of rotation. Overall, the centrifugal process was found to produce highly compacted green bodies while yielding a segregation effect due to wide particle size distribution.

Assessing the homogeneity of Actimask® acetaminophen and N-acetyl glucosamine mixture to predict further steps in the development of orodispersible tablets

One of the main problems in the production of tablets, which has significant negative consequences, is the segregation of the tablet mixture leading to inhomogeneity of dosage units, material losses in the manufacturing process and improperness of the specified pharmaceutical technical characteristics of the mixture. The aim of the research. This work aims at the pharmaceutical technical study of the substances N-acetyl-D-glucosamine and Actimask® Acetaminophen and determination the uniformity of the powder mixture of active pharmaceutical ingredients (APIs) to predict the optimal technology for obtaining a pharmaceutical formulation with the acceptable properties. Materials and methods. N-acetyl-D-glucosamine (Zhejiang Candorly Pharmaceutical, China) and Actimask® Acetaminophen (SpiPharma, USA) were used. Scanning probe microscope Solver P47N-PRO ("NT-MDT", Russia), optical microscope, flowability tester VP-12A, laser diffraction particle size analyzer SALD-2201 ("Shimadzu", Japan), liquid chromatograph Agilent 1260 Infinity II with Diode Array Detector (Agilent Technologies, USA), spectrophotometers Shimadzu UV-1800 ("Shimadzu", Japan) were used. The study of API pharmaceutical technical properties (microscopic characteristics, moisture absorption capacity, flowability, bulk volume and tapped volume, particle size distribution by sieve analysis and laser diffraction), as well as vibration simulation and following chromatographic study were carried out in this work. Results and discussion. The shape of the particles N-acetyl-D-glucosamine and Actimask® Acetaminophen, which was determined by microscopic analysis, demonstrated the possibility of N-acetyl-D-glucosamine particles to stick to Actimask® Acetaminophen ones. The experimental study allowed to reveal the hygroscopicity of both APIs; poor flowability, unsatisfactory Hausner ratio, and Carr index for N-acetyl-D-glucosamine; excellent flowability, Hausner ratio, and Carr index for Actimask®. Vibration caused segregation of the powder mixture. It was found that all layers do not meet the requirements and an excessive content of Actimask® is registered, which indicates the stratification of the powder mixture. Conclusions. The physical properties of the substances were determined and found to have significant differences in their particle size distribution. Segregation of the mixture after vibration was confirmed by laser diffraction and assay analysis. In order to solve the segregation problem, the granulation of N-acetyl-D-glucosamine may be proposed.