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New bismaleimides (BMI's) have been synthesized in the Bisphenol A, terphenyl, and tetraphenylketazine series. In three monomers, an additional functionality has been introduced with respect to conventional bismaleimides [viz., allyl, N-maleimido, and ketazine]; a new term, «reactive building block» BMI's, is introduced to describe such monomers. Cure profiles for new monomers have been determined by dynamic mechanical thermal analysis by supporting them on glass braids. Resins have been prepared on a multigram scale and have been studied by thermal gravimetric analysis for evaluation of thermal and thermooxidative stability

Polystyrene and poly(phenylene methylene) of relatively low molar mass (2000–3000) have been converted through nitro and amino derivatives into maleimido-functionalized oligomers. The latter have been characterized spectroscopically and oligomers and cured resins derived therefrom studied by thermal gravimetric analysis. Both polystyrene and poly(phenylene methylene) show greater thermal and thermo-oxidative stability than the corresponding maleimido derivatives. This trend is also observed when comparing poly(phenylene methylene) with the crosslinked resin derived from maleimidopoly(phenylene methylene). The opposite trend is observed for polystyrene and the cured resin derived from maleimidopolystyrene.

Dynamic mechanical thermal analysis (d.m.t.a.) profiles have been recorded for interaction of m-tolualdehyde azine and 3,5-dimethylpyridine N-oxide with the bismaleimide (BMI) derived from 3,3-diaminobenzophenone. Additional chemical events for each system are recognized at temperatures below the conventional BMI curing region. Resins prepared from the BMI/azine and BMIN-oxide systems have lower thermal stability than the neat resin but differences are moderate at low additive concentrations.

Novel aromatic polyimides prepared via the polymerization of monomeric reactants (PMR) approach and incorporating anthraquinone diamines in the main chain have been characterized. Imidization and crosslinking reaction profiles have been delineated by d.m.t.a. and the high-temperature mechanical and thermal properties of the thermoset resins examined. Elevated glass transition temperatures (> 300°C) are apparent in some resins while impairment of mechanical integrity is not evident below 450°C. All resins show good thermal and thermo-oxidative stability.

Polyimide oligomers (prepolymers) and resins of the PMR-15 type have been prepared from 5-norbomene-2,3-dicarboxylic half acid ester (NE), 3,3',4,4'-benzophenone tetracarboxylic diester (BTDE) and a series of diamines incorporating 1,2,3-triazole, quinoxaline, pyrido[2,3-b]pyrazine, pyrido[3,4-b]pyrazine, benzo[g]quinoxaline, pyrazino-[2,3]-d]pyridazine and bis(pyrido[3,4-b]pyrazino)benzene ring systems. Two tetraamines in the bis(pyrazino[2,3-d]pyridazino)benzene ring system were also employed. Selected diamine monomers from the above ring systems provde PMR-15-analogue resins of higher thermal and thermooxidative stability than PMR-15 itself. The physical behaviour during oligomerization and curing of PMR systems has been studied by dynamic mechanical thermal analysis (DMTA). Traces akin to that from PMR-15 are obtained using certain diamine monomers (e.g. triazole and pyrido[3,4-b]pyrazine containing) but a featureless thermogram is observed using tetraamines in the bis(pyrazino[2,3-dj]pyridazino) benzene system.

Investigation of the influence that monomer structure plays in determina tion of the nature of thermoset PMR polyimides has revealed new information regarding the cross linking reaction profile and resultant resin properties. Replacement of BTDE by ODPE as dianhydride shows reduced resin T g values. Synthesis of a new series of alkylene dianilines, with increasing flexibility within the homologous series, evinces lowered cross-linking onset temperatures and T g transitions. Increasing degrees of meta catenation in extended diamines also result in lowered T g values.