Heat‐resistant resins obtained from polymer precursors bearing β,β′‐dicyanovinyl terminal groups

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AbstractCertain polymer precursors of the general formula: magnified image where A is an aromatic structure bearing ester, amide, azomethine, or imide linkages were synthesized. Particularly, 4‐hydroxybenzaldehyde was condensed with malonitrile to afford 4‐hydroxy‐β,β′‐dicyanostyrene which reacted with a half molar amount of terephthaloyl dichloride in the presence of an acid acceptor. In addition, 3‐nitrobenzaldehyde was condensed with malonitrile to yield 3‐nitro‐β,β′‐dicyanostyrene that was catalytically hydrogenated to the corresponding amine. The latter reacted with a half molar amount of terephthaloyl dichloride, terephthaldehyde, pyromellitic dianhydride, or benzophenone tetracarboxylic dianhydride. The polymer precursors were characterized by elemental analyses as well as IR and 1H‐NMR spectroscopy. Their curing behavior was investigated by DTA. Crosslinked polymers were obtained by curing the monomers at 300°C for 24 h. They were stable up to 407–437°C in N2 and afforded an anaerobic char yield of 65–50% at 800°C. The thermal stability of resins was correlated with their chemical structures. © 1993 John Wiley & Sons, Inc.