Synthesis and characterization of bisimide amines and bisimide amine‐cured epoxy resins

Abstract A series of novel bisimide amines were synthesized and characterized and then utilized as curing agents with a standard epoxy resin, N,N′‐ tetraglycidyl‐methylenedianiline (TGMDA), known commercially as MY720. The bisimide amines (BIA's) were synthesized by reaction of 4,4′‐hexa‐ffuoroisopropylidine (biphthalic acid dianhydride) (6F anhydride) with aromatic and aliphatic diamines in dimethyl formamide at reflux temperatures in yields ranging 24 to 99 percent. The diamines used were 3,3′‐diaminodiphenylsulfone (3,3′‐DDS), 4,4′‐diaminodiphenylsulfone (4,4′‐DDS), 1,12‐dodecanediamine (1,12‐DDA), alone and as mixtures to produce the BIA's 6F‐3,3′‐ DDS, 6F‐4,4′‐DDS, 6F‐3,3′‐DDS‐4,4′‐DDS, 6F‐3,3′‐DDS‐1, 12‐DDA with various compositions, depending on the mode of addition and stoichiometry. The BIA's are isolated as mixtures containing monomer, oligomer, and polymeric species. They were characterized by elemental analysis, and high pressure liquid chromatography (HPLC). Epoxy resin specimens were fabricated by reaction of the standard epoxy (MY720) with the BIA and in some cases, mixtures of BIA and aromatic diamine, such as 3,3′‐DDS. The bisimide amine cured epoxies (IME's) were characterized for moisture absorption, thermal properties, physical and mechanical properties. The bisimide amine epoxy (IME) resins were also characterized as matrices in Celion 6000/bisimide amine cured epoxy (IME) composites. The relative toughness characteristics of each IME formulation was measured by the 10° offaxis tensile test by measuring the uniaxial tensile, shear strengths and shear‐strain‐to‐failure of the composite systems.