摘要 |
<p>The present invention provides an improvement in a process for preparing polyimide compositions from a mixture of monomers by the application of heat in two stages. The improvement comprises incorporating a cyclic peroxyketal catalyst, such as 3,6,6,9,9,-pentamethyl-3-(ethylacetate)-1,2,4,5-tetraoxycyclononane, into the monomer mixture prior to reaction.</p> |