Thermal analysis of cured halogenated bisphenol-C-epoxy resins

Halogenated epoxy resins of 1,1′bis(R,R′,4-hydroxy phenyl)cyclohexane (ECB: R = R′ = Cl; ECM: R = CH3 and R′ = Cl and EBB: R = R′ = Br) were cured using 10-50% pyromellitic dianhydride (PMDA), tetrachlorophthalic anhydride (TCP), 1,1′-bis(4-amino phenyl) methane (DDM) and 1,1′-bis (4-amino phenyl) cyclohexane (DDC) as curing agents at 230/150 °C. PMDA and TCP cured resins are insoluble in common solvents while DDC and DDM cured resins are soluble. In order to understand degradation kinetics, TG-DTA of cured resins was carried out at the heating rate of 15 °C/min in nitrogen atmosphere. Resins are thermally stable up to about 300-360 °C and involved two-step decomposition reactions. Endo- or exothermic DTA transitions supported either chemical or physical changes.