There are two primary methods for preparing prepregs: the dry method and the wet method. The dry method is further subdivided into the powder method and the hot-melt resin method (the latter also referred to simply as the hot-melt method). A powder prepreg is defined as a composite material in which resin powder adheres to the fibers and undergoes partial melting, resulting in a discontinuous resin phase where the fibers are not fully impregnated by the resin.
When comparing composite materials fabricated using dry-method prepregs versus wet-method prepregs, the former generally exhibits a superior surface finish and allows for more precise control over the resin content within the material. In the context of advanced composite materials for aerospace applications, hot-melt composites frequently demonstrate superior hydrothermal stability compared to solution-method composites: after immersion in boiling water for 48 hours, the retention rate of mechanical properties-such as flexural modulus and strength, as well as interlaminar shear strength-is significantly higher for hot-melt composites than for their solution-method counterparts, particularly regarding the retention of high-temperature mechanical properties.
