The characterization of the mechanical properties of microcrystalline cellulose: a fracture mechanics approach

Abstract

The mechanical properties of compressed beam specimens of microcrystalline cellulose (Avicel pH 101) have been assessed in terms of the tensile strength (sigma t), Young's modulus (E) and the following fracture mechanics parameters: the critical stress intensity factor (KIC), the critical strain energy release rate (GIC) and the fracture toughness (R). Increase in the compaction pressure used to form the beams resulted in compacts with higher values of tensile strength, Young's modulus, KIC, GIC and R, indicating that the compacts became less brittle as their porosity decreased. Extrapolation of the values of sigma t, E, KIC, GIC and R to provide values at zero porosity indicated that the material had values of 30 Nm m-2, 0.0103 GPa, 1.21 MN m-3/2, 1.98 x 10(2) Nm-1 and 2.19 x 10(3) Nm-1, respectively. These provide a range of values whereby a fuller characterization of the mechanical properties of pharmaceutical materials can be made.

Nondestructive Viscoelastic Analysis of Anisotropy in Compressed Tablets

“…Three-and four-point bending tests have been applied to long rectangular compacts for the determination of the Young's moduli of the various materials. [11][12][13][14] Indentation tests have also been applied to obtain measures of internal tablet structural characteristics. [15][16][17] Radebaugh et al 18 have studied beams made of compressed microcrystalline cellulose using a nondestructive method of oscillatory torsion.…”

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“…Thus a naive, yet logical, postulation may be that the predilection of MCC to deform predominately by plastic flow is the governing property of the interfacial strength of the more complex bilayer formulation. Indeed, a rise in the applied final compaction stress will result in the cohesive and interfacial strength of the compacted tablets increasing 6,7,8 .…”

DEM study of the mechanical strength of iron ore compacts

“…While various theories based on fracture mechanics (Mashadi and Newton, 1987) and bonding mechanisms (Nystrom et al, 1993) have been proposed, so far the bulk response of compacts under strength testing is not yet well understood. To investigate these phenomena using the DEM, various techniques have been proposed.…”