Mixtures of diglycidylether of bisphenol A (DGEBA) with different proportions of g-caprolactone (g-CL) were cured with ytterbium triflate as initiator. The curing was studied with differential scanning calorimetry (DSC) and thermo mechanical analysis (TMA). The results are presented in the form of a time-temperature-transformation diagram. The kinetic analysis was performed by means of the isoconversional integral procedure and the kinetic model was also determined using the Coats-Redfern method. Gelation was determined by means of combined experiences of DSC and TMA. The relationship between the glass transition temperature (T g ) and the degree of conversion a was determined by DSC. Using the isoconversional lines and the T g -a relationship, the vitrificacion curve was obtained. The methodology developed makes it possible to obtain the TTT diagram using only no-isothermal experiments with equivalent results to those using classical isothermal procedures. The addition of g-CL accelerates the curing and reduces the shrinkage after gelation and consequently the internal stresses in the material.

Diglycidyl ether of bisphenol A was cured with different proportions of γ‐caprolactone with ytterbium triflate as an initiator. The curing was studied by means of differential scanning calorimetry and Fourier transform infrared in the attenuated total reflection mode. The latter was used to monitor the competitive reactive processes and to quantify the conversions of the epoxide, lactone, and intermediate spiroorthoester groups. A partial depolymerization process from the cured material to free γ‐caprolactone was also identified. The formation of a stable carbocation and the coordinative capability of ytterbium triflate were the reasons for this unexpected process. The thermal and dynamic mechanical properties of the cured materials were determined with differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical thermal analysis. An increase in the proportion of γ‐caprolactone resulted in an increased curing rate, a decrease in the shrinkage after gelation, and a significant decrease in the glass transition temperature. The introduction of ester linkages into the three‐dimensional structure led to more thermally degradable thermosets. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1968–1979, 2007