X. Ramis et Jm. Salla, TIME-TEMPERATURE TRANSFORMATION (TTT) CURE DIAGRAM OF AN UNSATURATED POLYESTER RESIN, Journal of polymer science. Part B, Polymer physics, 35(2), 1997, pp. 371-388
The curing of an unsaturated polyester resin was studied by differenti
al scanning calorimetry (DSC), thermal mechanical analysis (TMA), and
Fourier-transform infrared spectroscopy (FTIR). The results are presen
ted in the form of a time-temperature-transformation (TTT) diagram. Th
e kinetic analysis was performed by means of the dynamic Ozawa method.
This analysis was used to determine the curing times (t) at various c
onversions (alpha) and temperatures(T) (isoconversional lines In t = A
+ E/RT). The equivalence of the Ozawa method and the isothermal isoco
nversional adjustment In t = A + E/RT were demonstrated. The relations
hip between the glassy transition temperature (T-g) and the conversion
alpha was determined by DSC. It was established that this relationshi
p 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 rela
tionship and the isoconversional lines, the vitrification curve was de
termined and it was observed that the vitrification times obtained are
consistent with those obtained experimentally when T-c = T-g. Gelatio
n 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 dete
rmined by DSC. It was seen that the material always gels at constant c
onversion, regardless of the curing temperature. The gelation line (ge
l times) were traced from the corresponding isoconversional line. (C)
1997 John Wiley & Sons, Inc.