Epoxy resins VIII. Thermal properties of 4,4′‐sulfonyldiphenol and bisphenol a epoxy resins

Epoxy resins of different molecular weights were prepared from epichlorohydrin and 4,4′‐sulfonyldiphenol (SDP) and from epicholorohydrin and bisphenol A (BA). They were cured at high temperatures with four different crosslinking agents, including aliphatic and aromatic amines. The thermal behaviour of these cured epoxy resins was studied. From the IPDT and IDT data it was observed that sulfone epoxy resins were thermally more stable than bisphenol A epoxy resins. The activation energies of thermal degradation of the resins were calculated and the implications of these results are discussed.