Effect of the concentration of the sizing agent on the carbon fibers surface and interface properties of its composites

The effect of the concentration of the sizing agent on performances of carbon fiber and carbon fiber composites has been investigated. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were applied to characterize carbon fiber surface topographies. At the same time, the single fiber strengths and Weibull distribution were also studied. The interlaminar shear strength and hygrothermal ageing test have been used to study the effect of fiber coatings on the interface of the composites. The analysis of the results shows that the sizing level is essential for improving the surface of carbon fibers and its composite performance. Different concentrations of the sizing agent have different contributions to the wetting performance of carbon fibers. Among the three concentrations of sizing agent studied (1 wt %, 1.5 wt %, and 2 wt %), the optimal sizing level is 1.5 wt %.