MOLECULAR-DYNAMICS SIMULATIONS OF THE TIME-DEPENDENT DIPOLAR CORRELATION-FUNCTION FOR ESTERS CONTAINING SUBSTITUTED 1,3-DIOXACYCLOHEXANE RINGS IN THEIR STRUCTURE

The temperature dependence of the components of the complex dielectric permittivity of cis/trans-2-phenyl-5-(acetoxymethyl)-5-ethyl-1, 3-dio xacyclohexane (HEDPA), model compound of the side group of poly[(cis/ -2-phenyl-5-ethyl-1,3-dioxacyclohexane-5-yl)methyl acrylate] (PHEDPA), is reported. The curve describing the temperature dependence of the d ielectric loss presents a prominent alpha absorption, centered at -45 degrees C at 1 Hz, associated with the glass-liquid transition. No sec ondary absorptions are detected in the glassy state down to -120 degre es C. The time dependence of the dipolar autocorrelation coefficient g (t) for HEDPA was simulated at different temperatures by MD procedures . Transformation of the autocorrelation coefficient from the time doma in to the frequency domain permits us to evaluate the normalized compo nents epsilon'/(epsilon(0) - epsilon(infinity) and epsilon ''/epsilon ''(max) of the complex dielectric permittivity epsilon(). The simulat ed values of epsilon'/(epsilon(0) -epsilon(alpha)) and epsilon ''/epsi lon ''( plotted as a function of log(omega/omega?(max)), where omega(m ax) is the angular frequency at the maximum of the alpha absorption, a re in rather good agreement with the experimental results obtained for HEDPA.