| 摘要 |
<p>A substantially microcrack- and blister-free composite can be made by drying an addition-type polyimide molding compound under suitable conditions to remove excess moisture. The molding compound includes a mixture of a polyimide resin and a plurality of carbon reinforcing fibers less than 3 mm long. The molding compound is placed into a heated material reservoir and transferred to a heated molding tool with a heated transfer ram. The ram establishes a molding pressure in a mold cavity in the molding tool sufficient to cure the molding compound into the desired composite. The molding compound is transferred to the mold cavity such that the molding compound is heated to a molding temperature at a rate of at least about 85 °C/min. The molding pressure and temperature are maintained in the mold cavity for a time sufficient to cure the molding compound into the desired composite. The composite is cooled and then heated to a suitable post-cure temperature at a rate sufficient to permit residual volatiles in the composite to diffuse out of the composite. The composite is held at the post-cure temperature for a sufficient time and then cooled. The invention also includes an article made by this method and a vented molding tool used in the method.</p> |
