ELECTRICAL RESISTIVITY AND CROSSLINKING IN THERMOSETTING RESINS

A linear unsaturated polyester resin was copolymerized with styrene, using benzoyl peroxide-tertiary amine and cobalt naphthenate-cydohexanone peroxide systems, in the range 45° to 70° C. Volume resistivity was measured using a Wheatstone bridge, and the results were compared with spectroscopic studies on the chemical reaction between styrene and the fumarate bonds. The disappearance of absorption bands at 915 and 985 cm.-1 was measured, and the carbonyl band employed as an internal standard. The logarithm of the resistivity showed an approximately linear relationship with the extent of disappearance of reactive double bonds, and the over-all activation energy determined by electrical resistivity was 21.1 kcal. per mole, compared with 20.6 by refractometry. The relationship of resistivity to dynamic mechanical tests is mentioned. © 1969, American Chemical Society. All rights reserved.