Research to Significantly Enhance Composites Survivability at 550 F in Oxidative Environments

Methylene dianiline (MDA) and its derivatives have been used in the synthesis of polyimides to yield polymers with characteristic low-density, high tensile strength, improved solubility in organic solvents, low-melt viscosities and high thermal stability (greater than 550 F) in air. Polyimides with such properties are desirable for use in aerospace systems, e.g., jet engines, airframe, missiles, and rockets where weight is critical. Recent research at Prairie View A&M University is focused on developing monomers to generate polyimides with enhanced performance over that of NASA s PMR-15. The objective of this work is to synthesize three ring aromatic diamines which are non-toxic and when reacted with the appropriate dianhydrides will yield polyimides with lower viscosity, improve processability, good retention of mechanical properties, and oxidative stability at high environmental temperatures. Modifications of the three ring aromatic diamines include replacing the methylene linkages with aromatic ethers by nucleophilic aromatic substitution reactions and incorporating mono- and di-substituents to the center aromatic ring. An update of current reactions involved in synthesis efforts to generate three ring aromatic monomers for polyimides with methylene, carbonyl, and ether linkages separating the aromatic moieties will be displayed.