DSC Analysis of Thermosetting Polyimides Based on Three Bismaleimide Resin Eutectic Mixtures

Three aromatic bismaleimide resins, 4,4′-bismaleimidodiphenyl methane (BMIDDM), 4,4′-bismaleimidodiphenylether (BMIDDE) and 4,4′-bismaleimidodiphenyl sulphone (BMIDDS) having various bridging groups from the corresponding amine monomers (4,4′-diaminodiphenylmethane (DDM), 4,4′-diaminodiphenylether (DDE) and 4,4′-diaminodiphenylsulphone (DDS)) were prepared. These resins were characterized by FTIR and NMR spectroscopy techniques. BMIDDM/BMIDDE andBMIDDM/BMIDDS mixtures at various concentrations were prepared to study the bismaleimide resin eutectic mixtures. Differential scanning calorimetry analysis was used to demonstrate the phase diagrams, the melting and solubility of each constituent of these binary systems (BMIDDM/BMIDDE and BMIDDM/BMIDDS) in different liquid and solid phases. Furthermore, in the present work the relationship between binary systems and the concept of a eutectic mixture with its extraordinary thermal properties is investigated. The eutectic melting point of the BMIDDM/BMIDDS system isconsiderable because of the much lower melting point of the above system compared to that of the synthesized monomer having the lowest melting point. It shows also a very easy way of using these materials in the molten state. The same DSC study on other mixtures, i.e., BMIDDM/BMIDDE and BMIDDE/BMIDDS is performed and the results are reported. The end results illustrate that by increasing the quantity of one monomer in the mixture, two melting points appear until they acquire the melting temperature of the eutectic composition (Te, a single and homogeneous peak). Impurities have similar effects on To and Texo. The findings of this work can be applicable in the transportation industry, particularly in areas such as civil and military aircraft industry, aerospace, marine and automotive sectors.