The influence of microporosity on the mechanical properties of bulk, scaffold, and composite scaffold biphasic calcium phosphate

摘要

The mechanical properties of bulk microporous biphasic calcium phosphate (BCP), monolithic BCP scaffolds with multi-scale porosity (macro- and microporosity), and BCP/polymethylmethacrylate (PMMA) composite scaffolds with multi-scale porosity were investigated in this work. The elastic properties of bulk BCP with varying micropore size and fraction were analyzed using resonant frequency testing. The compressive mechanical strength and fracture mechanisms of monolithic BCP and composite BCP/PMMA scaffolds with varying micropore size and fraction were characterized. The Young???s modulus of the resonant frequency samples showed an exponential dependence on micropore fraction and a linear dependence on density. The compressive strength of the monolithic BCP scaffolds was shown not to be significantly influenced by micropore size or fraction. Monolithic scaffolds exhibited brittle failure but with some degree of damage tolerance with complete failure occurring at over 15% strains. Composite BCP/PMMA scaffolds showed higher compressive strength than monolithic scaffolds and share stress-strain behavior similar to cellular solids. Fracture in monolithic and composite scaffolds occurred by crack propagation at rod junctions along the scaffold length and crack propagation along 45 degree planes, respectively.