Powder flowability of microcrystalline cellulose particles having different particle shapes, whose aspect ratios ranged from 1.8 to 6.4, was measured using the vibration shear tube method. Particles lubricated with magnesium stearate were also investigated in order to evaluate the effect of surface modification on powder flowability. Particles were discharged through a narrow gap between a vibrating tube edge and a flat bottom surface, where each particle experienced high shear forces, thus, overcoming adhesion and friction forces. Vibration amplitude was increased at a constant rate during measurement and the masses of the discharged particles were measured at consistent time intervals. Flowability profiles, i.e., the relationships between the mass flow rates of the discharged particles and their vibration accelerations, were obtained from these measurements. Critical vibration accelerations and characteristic mass flow rates were then determined from flowability profiles in order to evaluate static and dynamic friction properties. The results were compared with those obtained using conventional methods. It was found that angle of repose and compressibility were related to static and dynamic friction properties. Furthermore, it was found that particle aspect ratio more significantly affects powder flowability than does lubrication with magnesium stearate.
The flowability of powders with different mass median diameters ranging from micrometers to nanometers was measured using the vibration shear tube method. In the measurement system used in this study, the powder was discharged through a narrow gap between a vibrating tube edge and a flat bottom surface, where each particle could experience high shear forces to overcome the adhesion and friction forces. The vibration amplitude was increased during the measurement, and the mass of particles discharged was measured at constant time intervals.From the relationship between the mass flow rate and the vibration acceleration, static and dynamic properties of the powders were evaluated using the critical vibration acceleration, characteristic mass flow rate, and gradient of mass flow rate. The correlation between the static and dynamic properties was studied in detail.
The vibrating tube method can be used to evaluate the flowability properties of lubricated powders, and the experimental results provide useful information on the production of pharmaceutical solid dosage forms.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.