Prediction of the rheological properties of a curing thermoset system

Daly, John and Hayward, David and Pethrick, Richard (2013) Prediction of the rheological properties of a curing thermoset system. Macromolecules, 46 (9). pp. 3621-3630. ISSN 0024-9297

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Abstract

The variation of the viscosity as a function of the degree of conversion for an anhydride cured epoxy resin is modeled using a combination of a Monte Carlo statistical model of the polymerization process and constitutive equations describing the motion of the entities in the mix. The degree of conversion was monitored as a function of time using Fourier transform infrared spectroscopy over the temperature range 80–130 °C. The rate data are analyzed using the Kamal equation and activation energy of 57 and 64 kJ mol–1 obtained from the temperature dependence of the rate constants. The gelation and vitrification times for the cure process measured as a function of temperature were measured using a vibrating probe curometer. The variation of the viscosity measured experimentally and predicted are found to be similar when compared as a function of the degree of conversion. A time–temperature transformation was constructed and indicated that the gelation point occurred at approximately the same degree of conversion for all the temperatures investigated. The influence of the cure process on the final mechanical propeties of the resin is explored through dynamic mechanical thermal analysis. This paper indicates the possibility of predicting the variation of the viscosity prior to gelation based on the cure kinetics for reactive polymer systems.