Dielectric measurements were utilized in the investigation of the polymerization of epoxy resin Epon 826 with diethylenetriamine (DETA) as the crosslinking agent. The time variation of the dissipation factor and of the dielectric constant were measured continuously, while the epoxy system was held at a constant temperature. A range of 11 frequencies (330 cycles/sec.−10 Mcycles/sec.) at three different polymerization temperatures (30, 45, 60°C.) was covered. The test results are given as a set of curves for the dissipation factor and the dielectric constant versus time. Nearly all the dissipation factor curves have the same characteristic shape, with a well-defined minimum (valley) followed by a maximum (peak). The dielectric constant falls monotonously from a high initial value to a small final one that is specific for the fully cured resin. If the time at which the dissipation factor reaches the valley tv and the peak tp are plotted versus the logarithm of the frequency, two straight lines will be obtained. Such a plot can be utilized as an aid in controlling the curing process of cast resins.
No takes yet. Share an insight, caveat, or question.
Haran et al. (1965) studied this question.