Deconvolution of the relaxations associated with local and segmental motions in poly(methacrylate)s containing dichlorinated benzyl moieties in the ester residue

The relaxation behavior of poly(2,3-dichlorobenzyl methacrylate) is studied by broadband dielectric spectroscopy in the frequency range of 10-1 - 109 Hz and temperature interval of 303-423 K. The isotherms representing the dielectric loss of the glassy polymer in the frequency domain present a single absorption, called Β process. At temperatures close to Tg, the dynamical α relaxation already overlaps with the Β process, the degree of overlapping increasing with temperature. The deconvolution of the α and Β relaxations is facilitated using the retardation spectra calculated from the isotherms utilizing linear programming regularization parameter techniques. The temperature dependence of the Β relaxation presents a crossover associated with a change in activation energy of the local processes. The distance between the α and Β peaks, expressed as log (fmax;Β fmax;α) where fmax is the frequency at the peak maximum, follows Arrhenius behavior in the temperature range of 310-384 K. Above 384 K, the distance between the peaks remains nearly constant and, as a result, the α onset temperature exhibited for many polymers is not reached in this system. The fraction of relaxation carried out through the α process, without Β assistance, is larger than 60% in the temperature range of 310-384 K where the so-called Williams ansatz holds.