Electrical impedance spectroscopy of epoxy systems II: Molar fraction variation, resistivity, capacitance and relaxation processes of 1,4-butanediol diglycidyl ether/succinic anhydride and triethylamine as initiator

The Electric Impedance Spectroscopy (EIS) was used to evaluate resistivity, capacitance and relaxation processes of a cured epoxy system with different molar composition of 1,4-butanediol diglycidyl ether (EP), succinic anhydride (SA) and triethylamine (TEA) as initiator. The measurements were done over range frequencies between 10(-1) and 10(5) Hz. The systematic change of the molar fraction composition affected the resistivity and capacitance changes indicating gelation critical compositions according to the Flory's aggregation theory. The complex electric functions, dielectric constant epsilon(circle), electric modulus M-circle, impedance Z(circle) admittance Y-circle and the loss factor tan delta were utilized in order to investigate the relaxation processes. Relaxation peaks were observed for different molar fraction composition only in the imaginary impedance, the electric modulus and the tan delta as frequency functions. The relaxation frequencies obtained by Z '', M '' and tan delta evaluation are distinct and have been discussed in terms of resin components molar fraction dependence. (c) 2007 Elsevier Ltd. All rights reserved.