LAMINATING RESINS OBTAINED FROM 2,2'-(1,4-PHENYLENEDIVINYLENE)BISPYRIDINE BISMALEIMIDES AND MALEIMIDE-TERMINATED STYRYLPYRIDINE PREPOLYMERS

A new bismaleimide (2a), biscitraconimide (2b), and bisnadimide (4) were synthesized by reacting 2-amino-6-methylpyridine with an equimolar amount of maleic, citraconic, or nadic anhydride, respectively, and then with a half molar amount of 1,4-benzenedicarbaldehyde in the presence of acetic anhydride. They, as well as the intermediate amic acids (1a, 1b, and 3) were characterized by IR and H-1-NMR spectroscopy. The DTA thermograms showed that crosslinking of polymer precursors started at 180-212-degrees-C. The crosslinked resins obtained from 2a and 2b were stable up to 300-313-degrees-C and afforded anaerobic char yield of 53-60% at 800-degrees-C. The cured resin of 4 was less thermostable. In addition, end-capping of styrylpyridine prepolymers was accomplished by reacting 2,6-dimethylpyridine (n mol) with 1,4-benzenedicarbaldehyde (n + 1 mol) in acetic anhydride to yield a formyl-terminated styrylpyridine prepolymer. The latter reacted with the maleamic acid 1a (2 mol) to afford a series of maleimide-terminated styrylpyridine prepolymers MTSPs. They showed lower curing temperatures than did the ordinary poly (styrylpyridine). Their cured resins did not lose weight up to 310-344-degrees-C both in N2 or air and afforded anaerobic char yield of 66-72% at 800-degrees-C.