The curing kinetics of the liquid-crystalline epoxy resin sulfonyl bis(1,4-phenylene)bis[4-(2,3-epoxypropyloxy)benzoate] with 4,4 '-diaminodiphenylsulfone was investigated by nonisothermal differential scanning calorimetry. The relationship between the apparent activation energy (Ea) and the conversion was determined, and the effects of the molecular structure and the order of liquid crystallinity on Ea are discussed in detail. Some parameters were evaluated with the autocatalytic kinetic model of the SestakBerggren (SB) equation. The results show that there were some deviations of these simulation curves from the experimental curves at high heating rates and in the late stage of the curing reaction. The diffusion effect in the nonisothermal curing reaction is discussed, and a diffusion factor was proposed and introduced into the SB equation. Then, a modified SB equation was created, as follows: d/alpha=K/alpha(m)(1-alpha)(n) X 1/1+exp[C(alpha-alpha(c))], where alpha is the conversion, t is the time, m and n are reaction orders, K is rate constant, C is the diffusion coefficient, and alpha(c) is the critical conversion. The theoretical simulation curves agreed very well with the experimental data as determined with the modified SB equation, which may be more useful for describing and predicting the nonisothermal curing reaction kinetics of epoxy resin. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012