Preparation, characterization, and properties of novel bisphenol-A type novolac epoxy-polyurethane polymer with high thermal stability

In this study a series of modified bisphenol-A type novolac epoxy resins (MNEPs) were synthesized from bisphenol-A type novolac epoxy resin (NEP) and propionic acid (PA) by a one-step ring-opening reaction process in the presence of tetramethylammonium bromide as catalyst. Fourier transform infrared and (1)H-NMR were employed to confirm the chemical structures of the MNEPs. The spectra results indicated that MNEPs with different hydroxyl contents were obtained successfully by different ring-opening rates of NEP. In addition, Intercross-linked epoxy-polyurethane composites (MNEP-PUs) were also obtained by curing reaction among MNEP, cross linker polyisocyanate IL1351 and phthalic anhydride(PHA). The thermal stability of MNEP-PUs and the conventional polyol PU A450/IL1351 were determined and compared. The thermal analysis demonstrated that the obtained MNEP-PUs exhibited much better thermal stability than the conventional polyurethane system A450/IL1351, and the thermal stability of MNEP-PUs was correlated to the content of MNEP. Moreover, physico-chemical properties of MNEP-PUs such as pencil hardness, adhesive attraction, solvent resistance were reported. It demonstrated that incorporating MNEP into MNEP-PUs as inherent hardness of MNEP-PUs could greatly improve pencil hardness, adhesive attraction, water, acid and alkali resistance of MNEP-PUs.