Viscosity measurement monitor epoxy cure

Dielectric spectroscopy techniques (3) represent an exception to this limitation. In fact, Senturia et al. (4) recently described a microdielectrometric method for in situ measurement of epoxy cure. Using a novel microdielectric probe, they studied isothermal cures of digylcidyl ether bisphenol-A (DGEBA) epoxy in which the low-frequency dielectric relaxation time, r, is correlated with the bulk viscosity (4). In this paper we report preliminary results on the utilization of a viscosity-dependent fluorescence probe as an alternative (and possibly complementary) new approach with potential for in situ monitoring of epoxy cure kinetics. We also report the observation of a unique fluorescence "self-probe capability of tetraglycidyl-diaminodiphenyl methane (TGDDM) epoxy which has not been reported previously. 

Ve have described three fluorescence techniques for monitoring the cure of epoxy resins. The first one is based on intramolecular excimer fluorescence, the second one is based on the enhancement of fluorescence intensity with the medium viscosity, and the third one is based on the measurement of the translational diffusion coefficient of a fluorescent probe. Finally, we have demonstrated the fluorescence monitoring of the formation of a polyimide polymer. 

The third paper, by Levy and Ames, presents an interesting new way to monitor cure kinetics. They measure the viscosity of an epoxy system as it cures by use of a... 

Theoretical treatment of this polymerization is difficult because of the presence of both primary and secondary amine reactions as well as tertiary amine catalyzed epoxy homopolymerization. To obtain kinetic and viscosity correlations, empirical methods were utilized. Various techniques that fully or partially characterize such a system by experimental means are described in the literature ( - ). These methods Include measuring cure by differential scanning calorimetry, infra-red spectrometry, vlsco-metry, and by monitoring electrical properties. The presence of multiple reaction mechanisms with different activation energies and reaction orders (10) makes accurate characterizations difficult, but such complexities should be quantified. A dual Arrhenius expression was adopted here for that purpose. 

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