Abstract: Two kinds of T300/5405 prepregs were prepared by using the melt method and solution method, respectively, and the corresponding laminated composites were manufactured under the same processing conditions. By comparing the resin content, the internal defects (with C-Scan), the void content (with optical microscopy) and the fiber/matrix interface adhesion (based on the transverse crack density caused by tension in the [0 2/90 12 /0 2] laminates) of the two composites it was found that the lower void content and the better interface adhesion in the composite made with the prepreg prepared by the melt method are the main reasons that cause a better hygrothermal stability of this composite than that of the composite manufactured with the prepreg prepared by the solution method.

Key words: compo site, melt method, so lut ion method, hygro thermal stability