Browsing by Author "Jaime's, C"

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    Dynamic mechanical and dielectric relaxations in poly(pentachlorophenyl methacrylate)
    (WILEY-V C H VERLAG GMBH, 1998) Calleja, RD; Jaime's, C; Sanchis, MJ; San Roman, J; Gargallo, L; Radic, D
    In the present work, a comparative study of the dynamic mechanical and dielectric properties of two related polymers, poly(pentachlorophenyl methacrylate) (PPCPM) and poly(phenyl methacrylate) (PPhM), was carried out. In both polymers a similar relaxational behaviour was observed. Dielectric relaxation measurements give an improved resolution as compared with that obtained from dynamic mechanical techniques for a given process. The polymers show a secondary loss peak at approximately room temperature and a prominent peak overlapped with the conductivity electrode polarization contributions at temperatures above the glass transition temperature, studied by dielectric relaxation measurements. The activation energy associated with the relaxation process at low temperature is about 77 kJ.mol(-1) (which is similar to that observed in poly(alkyl methacrylates)) whose origin is attributed to the hindered partial rotation of the carboxymethyl group. An improved method of separating dipolar contributions from the non-dipolar ones was used to characterize the high temperature relaxation process and to obtain information from the diffusion coefficient of the conducting species.