TIME-RESOLVED FLUORESCENCE MEASUREMENTS FOR THE CHARACTERIZATION OF EPOXY SYSTEMS

Time-resolved fluorescence measurements, with Methyl Violet as probe, were used to determine some microviscosity and free volume parameters in the diglycidylether of bisphenol-A, in novolacs derived from bisphenol-A and in their mixtures. The fluorescence of the probe must compete with an internal rotational process of parts of the molecule. Due to the influence of surroundings on that process, the fluorescence lifetimes are related to mobilities in the system. Using known theoretical approaches for describing the mobility parameters in polymers or high-viscosity media, relations between the rate constant for the probe rotational and these parameters have been derived. With combined time-resolved fluorescence, viscosity-dependent and temperature-dependent measurements, fractional free volume data and glass transition temperatures have been determined. In novolac-diglycidyl ether mixtures, evidence for strong hydrogen bondings has been found.