Synthesis and characterization of phenylated phenylenediamine and bisphenol A diglycidyl ether epoxy networks

A new highly aromatic hardener, phenylated phenylenediamine (PDA), was synthesized utilizing a Diels-Alder reaction to afford a mixture of para and meta conformations. This new hardener was cured with bisphenol A diglycidyl ether (BADGE). To investigate the conformational mixture, pure 1,4-benzenediamine and 1,3-benzenediamine were cured with BADGE. DSC was employed to observe cure curves affording the onset (73, 74, and 146 degrees C for 1,4-benzenediamine, 1,3-benzenediamaine, and phenylated phenylenediamine, respectively), peak (128, 151, and 206 degrees C, respectively), and enthalpy change (385, 526, and 238 J/g, respectively), as well as the glass transition temperature (103, 151, and 212 degrees C, respectively). ATR-FTIR spectroscopy provided information on the structures of the cured network samples, including loss of oxirane and primary amine vibrations after curing. TGA and DMA were used to determine thermal stability (T-d,T-N2 = 332, 367, and 380 degrees C, respectively) and thermal mechanical properties including storage (E ' = 200, 150, and 350 MPa, respectively), loss modulus (E '' = 10, 10, and 40 MPa, respectively), and tan delta (102, 180, and 209 degrees C, respectively).