화학공학소재연구정보센터
Journal of Polymer Science Part B: Polymer Physics, Vol.35, No.2, 371-388, 1997
Time-Temperature Transformation (TTT) Cure Diagram of an Unsaturated Polyester Resin
The curing of an unsaturated polyester resin was studied by differential scanning calorimetry (DSC), thermal mechanical analysis (TMA), and Fourier-transform infrared spectroscopy (FTIR). The results are presented in the form of a time-temperature-transformation (TTT) diagram. The kinetic analysis was performed by means of the dynamic Ozawa method. This analysis was used to determine the curing times (t) at various conversions (alpha) and temperatures(T) (isoconversional lines In t = A + E/RT). The equivalence of the Ozawa method and the isothermal isoconversional adjustment In t = A + E/RT were demonstrated. The relationship between the glassy transition temperature (T-g) and the conversion alpha was determined by DSC. It was established that this relationship is one-to-one and independent of mass, initiation system, and curing temperature (T-g). The T-g-alpha relationship was adjusted using the DiBenedetto equations and heat capacity data. Using the T-g-alpha relationship and the isoconversional lines, the vitrification curve was determined and it was observed that the vitrification times obtained are consistent with those obtained experimentally when T-c = T-g. Gelation was determined by TMA, the material being considered gelled when it reached sufficient mechanical stability for the TMA measuring probe to become embedded in it. At that moment the conversion reached was determined by DSC. It was seen that the material always gels at constant conversion, regardless of the curing temperature. The gelation line (gel times) were traced from the corresponding isoconversional line.