Synthesis and properties of 1,3,4-oxadiazole-containing high-performance bismaleimide resins

Two novel bismaleimide (BMI) monomers containing 1,3,4-oxadiazole, i.e., 5-tert-butyl-1,3-di[5-(4-maleimidophenyl)-1,3,4-oxadiazole-2-yl]benzene (Buoxd) and 4,4'-[5-(4-maleimidophenyl)-1,3,4-oxadiazole-2-yl]diphenyidimethylsilane (Sioxd), were designed, synthesized and co-polymerized with 4,4-bismaleimidodiphenylmethane (BMDM) to yield a new series of high-performance bismaleimide resins. Both monomers obtained are readily soluble in common organic solvents, such as dichloromethane and chloroform, enabling an easy solution processing. The thermal properties of the two monomers were carefully studied by the differential scanning calorimetry (DSC), optical microscopy and thermogravimetric analysis (TGA, simultaneous DSC). The BMI resins based on a mixture of Buoxd (or Sioxd) and BMDM in a weight ratio of 10% were prepared. DSC investigations showed that the thermal curing of the BMI resins could be accomplished at a lower temperature than the thermal curing temperatures of Buoxd and Sioxd, and the thermal processing window, i.e., the temperature range between the melting transition and thermal curing process, was over 26 degrees C. The thermal properties and thermal mechanical properties of the resulting BMI resins were investigated by DSC, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). No glass transition temperature was found in the range of 50-350 degrees C, and very good thermal stability (T-d > 490 degrees C in nitrogen) and high thermo-oxidative stability (Td > 460 degrees C in air) were revealed. Composites composed of the above BMI resins and glass cloth were also prepared, which showed high bending modulus (> 1.6 GPa) at a very high temperature (e.g., 400 degrees C). (c) 2006 Elsevier Ltd. All rights reserved.Polymer ScienceSCI(E)0ARTICLE1129-1384