Dielectric relaxation in chlorinated polyethylene polypropylene copolymers

Abstract

[EN] Dielectric relaxation measurements were carried out on eight chlorinated polyethylene-polypropylene (PEPP) copolymers in the range of temperatures covering the main dielectric absorption. Chlorination of PEPP is expected to change the dynamic dielectric properties gradually with increasing amount of chlorine in the polymer chains. Thus, in the present study, increasing degrees of chlorination give a clear shift of the glass transition temperature towards higher values, except in the range between 40 and 51% chlorine, where an anomalous behaviour was observed. The same tendency is also observed in the relaxation strength (Delta epsilon). The value of Delta epsilon has been estimated by using a nonlinear squares regression program (LEVM6) to calculate the parameters of the Havriliak-Negami empirical equation. It appears reasonable to assume that the anomalous behaviour observed can be attributed to a compensation of the dipolar moments of chlorine groups in the macromolecules.