Experimental Characterization of Micro-Crystalline Cellulose Particles with a Micro Compression Tester
Abstract
Biopolymeric particles such as microcrystalline cellulose (MCC) are used as excipients in direct compression tableting due to their high degree of plasticity. Determination of the mechanical behavior of such particles on an individual scale might give better insight into their tableting properties. Due to such particles being highly irregular and highly plastic, conventional contact mechanics cannot be applied to them. Hence, inorder to characterize such particle's deformation behaviour, it was decided to experimentally analyze Avicel® PH-200, a grade of MCC. Load-unload experiments were performed on individual particles of various sizes using a Shimadzu MCT-510 micro compression tester (MCT). A relation between the size and shape of the particles and their deformation behavior was obtained empirically. The master deformation behavior of a hypothetical spherical particle was found and a scaling law for spheroidal particles with dierent aspect ratios was observed. Uncertainty in the proposed contact law was also obtained from the experimental data. The master behavior can predict deformation of Avicel® PH-200 over a wide range of particle sizes and aspect ratios. Two methods were proposed to obtain the scaling law and the subsequent master deformation behavior. In the rst method, stress was considered to be a function of strain whereas in the second method, strain was considered as a function of stress. Predictions were done using these methods over the experiments that were involved in developing the methods. The methods were compared with each other and the method most suitable for these particles was identied. It is worth noting that the methods that were investigated do not depend on any specific mechanical properties of the material but rather on the general behavior of the particles under diametric compression. Therefore, these methods can be used to particles made up of dierent materials that show a similar deformation behavior under diametric compression.
Degree
M.S.A.A.
Advisors
Gonzalez, Purdue University.
Subject Area
Aerospace engineering|Mechanical engineering
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