Moisture absorption behavior of C3D/EP composite and effect of external stress

A three-dimensionally (3-D) braided carbon-fiber-reinforced epoxy (C3D/EP) composite has been produced by vacuum impregnation technique by using a low-viscosity epoxy. The present study is carried out in order to determine the water absorption characteristics of this 3-D composite for internal fixation applications. Effect of external load on water uptake and changes in flexural, shear and impact strengths as a result of moisture absorption has been investigated considering the bone fixation devices are attacked by moisture and stress. The kinetics of moisture absorption by the stressed and unstressed 3-D composite samples has been determined for absorption at body temperature (37±0.5 °C). It has been shown that the water absorption characteristic of this C3D/EP composite cannot be described by using Fickʹs law may be due to its high void content and/or its 3-D fiber structure. Results clearly demonstrate the contribution of external stress on water absorption behavior and changes in mechanical property. The external stress has been found to increase the moisture content and mechanical properties reduction at earlier stages. At later stages, a contrary trend is observed. Mechanisms are proposed to interpret our experimental results.