ANOMALOUS TRENDS IN CONDUCTIVITY DURING EPOXY-AMINE REACTIONS

Measurements were carried out of conductivity due to migrating charges as a function of extent of reaction for a series of epoxy-amine formu lations. All systems were characterised by the reaction mechanism comm on to this generic group of materials and by an increase in the steady shear viscosity during reaction. The measured conductivity, however, followed one of three distinct patterns as a function of extent of rea ction. Intuitively unexpected, and hence particularly interesting, was the observed increase in conductivity during reaction in several form ulations. This communication marks the first time that such response h as been reported in the literature. An explanation of the observed tre nds was offered in terms of an interplay between the contributions of extrinsic and intrinsic migrating charges to the overall (measured) co nductivity. Without such information, all correlations between the mea sured conductivity and the major processing parameters (viscosity, ext ent of reaction) remain strictly batch-specific and empirical. (C) 199 8 Elsevier Science Ltd. All rights reserved.