Abstract
Purpose
To test two hypotheses. First, autonomic healing is achievable in a commercially available poly (methyl methacrylate) bone cement brand that is widely used to anchor total joint replacements. Secondly, in this self-healing cement, the fatigue crack propagation (FCP) rate is critically dependent on the relative amount of the mass of the healing agent (endo-isomer of dicyclopentadiene (DCPD) embedded in poly (urea-formaldehyde) (PUF) microcapsules (diameter = 226 ± 51 μm)) (MDM) to that of the catalyst (a first-generation Grubbs’ catalyst) (MGC). (Note that, in this work, the term, “autonomic healing” or “self healing”, refers to the ability of the material, after having been damaged during service, due to formation of cracks, for example, to restore its initial mechanical performance without the need for any external intervention).
Methods
The strategy that was developed by White et al. For room-temperature autonomic healing of a neat polymeric material was used. The DCPD-filled PUF microcapsules and the catalyst were blended with the cement's powder in a mortar bowl using a polymeric spatula, and the blended powder mixture and the cement's liquid monomer were mixed under a partial vacuum. FCP tests were performed on specimens of seven study groups: the control cement (CMW™1), four sets having different values of MDM/MGC, one set in which only the DCPD-filled microcapsules were blended with the CMW™1 powder, and one set in which only the Grubbs’ catalyst was blended with the CMW™1 powder.
Results
An index of the self-healing achieved, as computed using the estimated FCP rates, was within the range reported in the literature for autonomically-healing neat polymeric materials. Furthermore, the variation of the estimated FCP rate with MDM/MGC suggests that changes in this rate is critically dependent on change of MDM/MGC.
Conclusion
The results supported both of the study hypotheses.