DC-ELECTRICAL CONDUCTIVITY AS A METHOD FOR MONITORING RADIATION CURING OF UNSATURATED POLYESTER RESINS .1. MEASUREMENT CONDITIONS AND COMPARISON WITH EXTRACTION ANALYSIS DATA

Radiation curing of unsaturated polyester resin with styrene was chose n to test the d.c.-electrical conductivity method for in-source monito ring of the curing reaction. The dependence of electrical conductivity on electrical field strength and temperature were tested to determine the optimal experimental conditions. The relationship between changes of electrical conductivity and the extent of crosslinking in the resi n was determined by the extraction of the soluble fraction from the sa mples irradiated to different doses for which the change of electrical conductivity was determined previously. Good correlation was found be tween the extent of the reaction as assessed from both the mass of gel and the UV absorption of unreacted styrene and the results of electri cal measurements.