Keywords: PMMA bone cement, acrylic bone cement, joint replacement, mechanical properties, morphology, design of experiments, DOE, montmorillonite nanoclay, nanocomposites, nanomaterials
Incorporation of montmorillonite nanoclay to acrylic bone cement: effect on mechanical properties and morphology
The principal mode of loosening of joint replacements is bone cement mantle failure, which is made worse with formation of microcracks under mechanical load. In this in vitro study the effect of incorporating montmorillonite nanoclay on the mechanical properties and morphology of bone cement was investigated. This study was conducted using a Design of Experiments (DOE) approach, which facilitated the predominant factors affecting the physical and mechanical properties of the nanocomposite cement being determined. X-ray diffraction and transmission electron microscopy were used to determine the intrinsic properties of the nanocomposite bone cements. The significant factor levels that improved the mechanical properties and morphology of nanocomposite bone cement were the level of nanoclay loading, the time initiator was added to the suspension, ultrasonic mixing time and amplitude of ultrasonic probe. Adopting the predominant factors at their optimum levels produced nanocomposite cement demonstrating a higher elastic modulus when compared to the control bone cement. X-ray diffraction suggested an increase in the d-spacing between the silicate layers for all nanocomposite cements investigated, which was confirmed using transmission electron microscopy. Furthermore, a direct relationship was demonstrated between the nanoclay d-spacing, degree of nanoclay agglomeration and the final properties of the nanocomposite cement.