Stress transfer analyses of poly(L-lactic acid)/hydroxyapatite composites by synchrotron radiation

In this study, the stress transfer behaviors of poly(L-lactic acid) (PLLA)/hydroxyapatite (HAp) composites during tensile tests were investigated by in situ synchrotron X-ray diffraction. When tensile stress was applied to the composite, a diffraction peak assigned to the (211) plane of HAp shifted to a lower angle, and the stress was transferred through the interface between the PLLA matrix and HAp fillers. The stress distributed to the HAp fillers was several times greater than the applied stress. The dependence of the stress transfer on the fraction ratio of the HAp filler to the filler size was attained. Furthermore, the correlation between the macroscopic mechanical properties and stress transfer behaviors of the composites during tensile deformation and fracture was revealed using in situ X-ray diffraction measurements with synchrotron radiation. At the yielding points, interfacial failure between PLLA and HAp was determined. In situ X-ray diffraction measurements were shown to be reliable and provided a practical analysis method to obtain an understanding of the dynamic process of the mechanical deformation of composites. In this study, the stress transfer behaviors of poly(L-lactic acid) (PLLA)/hydroxyapatite (HAp) composites during tensile tests were investigated by in situ synchrotron X-ray diffraction. The effects of HAp fillers and their size on the stress transfer behaviors were discussed. Furthermore, the correlation between the macroscopic mechanical properties and stress transfer behaviors of the composites during tensile deformation and fracture was revealed. At the yielding points, interfacial failure between PLLA and HAp was determined.