Prepreg curing process for preparing composites having superior surface finish and high fiber consolidation

A process for curing a prepreg, comprising the steps of:

• providing a prepreg comprising a thermosetting resin composition and fiber, wherein the thermosetting resin composition comprises oxazines and one or more of epoxies, episulfides, oxetanes, thioxetanes, maleimides, nadimides, itaconimides, cyanate esters, and oxazolines, and the fiber is made from polyacrylonitrile, pitch, rayon or acrylic;
• placing the prepreg under reduced pressure of greater than 686 mm Hg (13.3 psi);
• exposing the prepreg under reduced pressure to a first elevated temperature of about 200° F. for a time of about 2 hours to remove substantially all volatile materials in the prepreg;
• optionally, exposing the prepreg under reduced pressure to a second elevated temperature of about 290° F. for a time of about 3 hours to remove any remaining volatile materials in the prepreg;
• exposing the prepreg under reduced pressure to a third elevated temperature of about 360° F. for a time of about 2 hours to cure the prepreg;
• and
• exposing the cured prepreg with or without reduced pressure to a fourth elevated temperature condition of about 90° F.