Lewis Gladius, Wellborn Brandon, Jones Ii Leroy, Biggs Patrick
Department of Mechanical Engineering, The University of Memphis, Memphis, Tennessee - USA.
J Appl Biomater Biomech. 2009 May-Aug;7(2):90-6.
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 plusmn; 51 mu;m)) (MDM) to that of the catalyst (a first-generation Grubbsrsquo; catalyst) (MGC). (Note that, in this work, the term, ldquo;autonomic healingrdquo; or ldquo;self healingrdquo;, 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).
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 cementrsquo;s powder in a mortar bowl using a polymeric spatula, and the blended powder mixture and the cementrsquo;s liquid monomer were mixed under a partial vacuum. FCP tests were performed on specimens of seven study groups: the control cement (CMWTM1), four sets having different values of MDM/MGC, one set in which only the DCPD-filled microcapsules were blended with the CMWTM1 powder, and one set in which only the Grubbsrsquo; catalyst was blended with the CMWTM1 powder.
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.
The results supported both of the study hypotheses.
验证两个假设。其一，在广泛用于固定全关节置换物的一种市售聚甲基丙烯酸甲酯骨水泥品牌中可实现自主愈合。其二，在这种自愈合水泥中，疲劳裂纹扩展（FCP）速率关键取决于愈合剂（嵌入聚脲甲醛（PUF）微胶囊（直径 = 226 ± 51μm）中的二环戊二烯（DCPD）内异构体）（MDM）与催化剂（第一代格拉布催化剂）（MGC）的相对质量。（注意，在本研究中，“自主愈合”或“自愈合”一词指材料在服役期间因形成裂纹等而受损后，无需任何外部干预即可恢复其初始力学性能的能力）。
采用怀特等人开发的用于纯聚合物材料室温自主愈合的策略。将填充DCPD的PUF微胶囊和催化剂用聚合物刮刀在研钵中与水泥粉末混合，然后将混合后的粉末混合物和水泥的液态单体在部分真空下混合。对七个研究组的试样进行FCP测试：对照水泥（CMWTM1）、四组具有不同MDM/MGC值的试样、一组仅将填充DCPD的微胶囊与CMWTM1粉末混合的试样以及一组仅将格拉布催化剂与CMWTM1粉末混合的试样。
使用估计的FCP速率计算得出的自愈合指数在文献报道的自主愈合纯聚合物材料范围内。此外，估计的FCP速率随MDM/MGC的变化表明，该速率的变化关键取决于MDM/MGC的变化。
结果支持了两项研究假设。
