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 10⁵ 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 ε^•, electric modulus M^•, impedance Z^•, admittance Y^• and the loss factor tan δ 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 δ as frequency functions. The relaxation frequencies obtained by Z″, M″ and tan δ evaluation are distinct and have been discussed in terms of resin components molar fraction dependence.