Structural characteristics and properties of polyurethane modified TDE-85/MeTHPA epoxy resin with interpenetrating polymer networks

Diglycidyl-4, 5-epoxycyclohexane-1, 2-dicarboxylate(TDE-85)/methyl tetrahydrophthalic anhydride (MeTHPA) epoxy resin was modified with polyurethane(PU) and the interpenetrating polymer networks(IPNs) of PU-modified TDE-85/MeTHPA resin were prepared. The structural characteristics and properties of PU-modified TDE-85/MeTHPA resin were investigated by Fourier transform infrared(FTIR) spectrum, emission scanning electron microscopy(SEM) and thermogravimetry(TG). The results indicate that epoxy polymer network (I) and polyurethane polymer network (II) of the modified resin can be obtained and the networks (I) and (II) interpenetrate and tangle highly each other at the phase interface. The micro morphology presents heterogeneous structure. The integrative properties of PU-modified TDE-85/MeTHPA epoxy resin are improved obviously. The PU-modified TDE-85/MeTHPA resin's tensile strength reaches 69.39 MPa, the impact strength reaches 23.56 kJ/m, the temperature for the system to lose 1% mass (t(1%)) is 300 degrees C, and that for the system to lose 50% mass (t(50%)) is 378 degrees C. Compared with those of TDE-85/MeTHPA resin, the tensile strength, impact strength, t(1%) and t(50%) of the PU-modified resin increases by 48%, 115%, 30 degrees C, 11 degrees C, respectively. The PU-modified TDE-85/MeTHPA resin has the structure characteristics and properties of interpenetrating polymer networks.