Effect of thermo-oxidative aging on three-dimensional and four-directional braided carbon fiber/epoxy composite

Abstract

An experimental study was performed to investigate the effect of high temperature exposure on flexural properties of the three-dimensional and four-directional braided carbon fiber/epoxy composite and the corresponding neat resin. For this purpose, samples were exposed to 90 C, 120 C, 150 C, and 180 C (below and above the glass transition temperature of the matrix resin) for various periods of time up to 13 days. The flexural properties combining with Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), weight loss, scanning electron microscope (SEM), and optical microscope analyses were performed on the unaged and aged samples. The results revealed that the thermo-oxidative behavior of the braided composite was significantly different from the neat resin. The flexural strength of the neat resin decreased dramatically due to the oxidation degradation of the sample surface when the aging temperature was equal to its glass transition temperature. The extensive degradations of both the matrix and the fiber/ matrix interface, especially for the interface, were responsible for the significant decrease in flexural strength of the braided composite. The flexural strength retention rates of the braided composite were higher than that of the neat resin after exposure to 90 C, 120 C and 150 C because the integral structure of the braided composite can make the fiber bear flexural force together although the matrix resin and the fiber/matrix interface had a certain degree of damage after longtime thermo-oxidative aging.

Accelerated thermal ageing of epoxy resin and 3-D carbon fiber/epoxy braided composites

“…Tsotsis [2][3][4][5] found that the weight loss during thermo-gravimetric test could not be used as criteria for material acceptance. The properties' changes, such as mechanical properties [6][7][8][9][10][11][12], physical properties [13], thermal conductivity [14] and the development of microcracks [15][16][17] caused by thermal treatment have been extensively studied and documented. Compared with isothermal ageing, thermal cycling can accelerate the damage processes and especially the matrix crack propagation from the surfaces to the core of the laminate [18].…”

Temperature effects on structural integrity of fiber‐reinforced polymer matrix composites: A review

“…made braided carbon fiber/graphene/epoxy composites by introducing graphene between carbon fibers and matrix using liquid phase deposition. With this gradient interface layer, the thermal conductivity decreased steadily from carbon fiber to matrix resin, resulting in good interface bonding, thereby effectively reducing thermo‐oxidative damage to the interface, improving the thermal oxidative stability of the braided composites …”

Improved thermo-oxidative stability of three-dimensional and four-directional braided carbon fiber/epoxy hierarchical composites using graphene-reinforced gradient interface layer

“…1(a)). The production processes for the composites and the neat resin are covered elsewhere [6]. The final specimens of the BGCs and BCs are illustrated in Fig.…”

“…Unfortunately, however, the flexural strength (FS) of the 3D-4Dir braided composite decreases significantly when the fiber/matrix interface performance declines extensively after TOA [6].…”