| 摘要 |
<p>Prepreg precursors and other normally non-flowable resinous semi-solid or viscous liquid polyimide precursor compositions often need to be transformed into free-flowable liquids without dilution and without causing changes in their chemical composition. Such compositions are composed of (a) a diester of an aromatic tetracarboxylic acid, (b) an aromatic diamine, (c) a polyamic acid producible from (i) an aromatic diamine and (ii) a dianhydride of an aromatic tetracarboxylic acid, and (d) an inert solvent in an amount insufficient to provide a flowable liquid at room temperature. Such compositions readily undergo chemical change (amidization and imidization) when subjected to heating in a conventional oven because of local overheating, and poor heat transfer within the body of the composition. These problems are overcome by subjecting the composition to microwave radiation of intensity sufficient to convert at least a portion of the composition into a flowable liquid without causing a significant change in its chemical composition.</p> |
