THE USE OF TIME-TEMPERATURE SUPERPOSITIONING IN STUDYING THE FRACTUREPROPERTIES OF RUBBER-TOUGHENED EPOXY POLYMERS

The fracture energies, G(Ic), of an unmodified and a rubber-modified e poxy have been ascertained as a function of test temperature and rate. A time-temperature superpositioning technique has been adopted in ord er to produce a master curve of the fracture energy, G(Ic), versus the reduced rate of test, t(f)/a(T); where t(f) is the time-to-failure an d a(T) is the time-temperature shift factor. The value of the shift fa ctor, a(T), as a function of test temperature has been determined from time-temperature shifting the yield stress and the modulus data for t he materials. The master curve of G(Ic) versus t(f)/a(T) has been mode lled and the values of the constants employed in the model have been d educed. The values of the constants so determined are discussed with r espect to the microstructures of the epoxy polymers.