Abstract: In this paper, the bending properties of 3-D carbon/epoxy interlock composite unaged and aged for 16-days at different temperature (90 ℃, 110 ℃, 180 ℃) were studied by quasi-static loading. The influences of aging temperature on bending properties were observed by macroscopic observation and SEM as well. The influences of aging temperature on epoxy properties, post-curing, heat flow and chemical structure were studied by differential scanning calorimetry (DSC) and infrared spectrum (IR Spectrum), respectively. The result indicated as follows. The post-curing and thermal degradation can be found in epoxy aging at the same time. For Composite aged for 16 days, the bending strength of composite aged at 90 ℃ increased obviously because the post-curing of epoxy play an important role in aging. When composite aged at 110 ℃, the bending strength decreased unobviously which were caused by slightly thermal degradation. For composite aged at 180 ℃, the bending strength declined distinctly and the flexural modulus decreased as well due to the strong thermal degradation of the epoxy resin and the fiber/resin interface crack which were observed by SEM. In addition, less damage area on top of composite aged at 90 ℃ than others could be found form the damage photographs. These were consistent with the strength characteristics which indicated in above situation that composite aged at 90 ℃ had better bending properties.

Key words: isothermal aging, 3-D angle-interlock woven composites, DSC and IR spectrum, bending properties