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 (σ_t), Young's modulus (E) and the following fracture mechanics parameters: the critical stress intensity factor (K_IC), the critical strain energy release rate (G_IC) 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, K_IC, G_IC and R, indicating that the compacts became less brittle as their porosity decreased. Extrapolation of the values of σ_t, E, K_IC, G_IC and R to provide values at zero porosity indicated that the material had values of 30 Nm m⁻², 0ṁ0103 GPa, 1ṁ21 MN m^−3/2, 1ṁ98 times 10² Nm⁻¹ and 2ṁ19 times 10³ Nm⁻¹, respectively. These provide a range of values whereby a fuller characterization of the mechanical properties of pharmaceutical materials can be made.