Characterization of the Crosslinking Kinetics of a Thin Polymeric Layer by Real‐Time Dielectric Relaxation Spectroscopy

The crosslinking kinetic of a thin polymeric layer based on a prepolymer of a phthalic aciddiallylester was studied by real‐time dielectric spectroscopy in the frequency range from 10 –1 to 10 5 Hz. With increasing reaction time the real part of the dielectric function ε ′ decreases. The time dependence of ε ′ can be described by a stretched exponential function with a stretching exponent of 0.5. This means that the influence of the chemical reaction on ε ′ cannot be described by a first order kinetic. From the temperature dependence of the characteristic time constant an activation energy of 71 kJ/mol could be estimated for the reaction. From the dielectric loss data the change of the relaxation rate of the dynamic glass transition f pα with the reaction time is obtained. After a temperature dependent induction period f pα decreases very strongly. No plateau value which corresponds to a glass transition in the crosslinked system is obtained for long reaction times.