Synthesis and Thermal Behaviour of Some Bismaleimides with Hexafluoroisopropylidene Groups

Bismaleimide polymers are an important high performance polymer class, due to their attractive combination of physical, chemical and mechanical properties. They can also be used as resin matrices for advanced composites. These resins have high thermostability, tensile strength and modulus, good flame resistance, excellent chemical and corrosive resistance, as well as low water sensitivity. These compounds have good retention of thermomechanical properties even after long ageing intervals at 250°C [1-7]. A large variety of polybismaleimides(PBMI) bearing end-capped reactive maleimide has been developed in the last year, in order to improve their processability and their properties. Still, most BMIs have also a number of disadvantages, such as: high melting and curing temperatures, poor solubility in ordinary solvents, brittleness of the final polymers due to the high crosslink density in the polymeric network [8-12]. Further attemps have been made to improve the processability and properties of these polymers by using monomers with different structures. Based on this concept, our main concern was to prepare bismaleimidic monomers having: -hexafluoroisopropylidene groups; -substituents in para or meta position; -with or without ether or ester units.