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Improved chemistry was explored for the formation of acetylene terminated isoimide resins of varying lengths. The resins were prepared by forming an amic acid precursor from benzophenone tetracarboxylic acid dianhydride, 1,3 - bis (3-aminophenoxy) benzene and 3-aminophenylacetylene followed by cyclodehydration by N,N'-dicyclohexylcarbodi-imide. A Fourier Transform infrared analysis method was devised to quantitatively determine the amounts of isoimide, imide, and amic acid present in the resins. The optimized chemistry was then applied successfully to the preparation of a series of lower cost acetylene terminated isoimides by substitution of 4,4'-oxydianiline for the 1,3-bis (3-aminophenoxy) benzene. The resultant resins were found to be curable at 316 C to crosslinked imides with Tg values in excess of 316 C for oligomer lengths of 1, 2 and 3. Thermal and mechanical studies were carried out on all of the resins. (Author)