Preparation of Novel Epoxy Resins Bearing Phthalazinone Moiety and Their Application as High-Temperature Adhesives.

Most polymer-based adhesives exhibit some degree of degradation at temperatures above 200 °C, and so there is a need for the development of adhesives that can be used at high temperatures. A series of poly(phthalazinone ether nitrile sulfone ketone)s terminated with epoxy (E-PPENSK) and amine (A-PPENSK) groups have been prepared, which have been used as precursors can be applied for high-temperature resistant epoxy adhesives. The structured of these E-PPENSK (epoxy resin) and A-PPENSK (curing agent) components have been characterized by ¹H nuclear magnetic resonance (NMR) and Fourier transform⁻infrared spectroscopy (FT⁻IR) studies, with the effects of molecular weights and molar ratios on the gel content of their polymers being determined. Cured epoxy resins derived from E-PPENSK and A-PPENSK showed good thermal stability, with an optimal resin retaining 95% of its weight at 484 °C, which gave a char yield of 62%. This adhesive was found to exhibit good mechanical strength, with a single-lap adhesive joint (A-3000/E-6000) exhibiting a shear strength of 48.7 MPa. Heating this adhesive at 450 °C for 1 h afforded a polymer that still exhibited good shear strength of 17.8 MPa, indicating that these adhesives are potentially good candidates for high-temperature applications.