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The time rate change of the polarization vector of an isotropic polymer containing dipoles along the chain contour under an electric field is studied using the extended irreversible thermodynamics formalism. The analysis leads to the formulation of phenomenological equations of Havriliak-Negami for the dielectric permittivity that give a good account of the dielectric α and normal mode peaks associated,...
In this study, a copolyester of poly(triethylene glycol p,p′-bibenzoate-co-(R)-3-methyl adipate) was prepared. The mesophase texture, the thermal and dielectric properties (a.c.-dynamical as well as thermostimulated depolarization currents) were studied. X-ray diffractograms reveal a relatively stable mesophase smectic Sc, whereas DSC shows on heating only the glass transition and the endotherm due...
Cryogenic dielectric measurements corresponding to the γ-relaxation zone have been made for poly(chloroethyl methacrylate) and poly(chloropropyl methacrylate). Molecular mechanics calculations using the Allinger MM2 force field have been carried out on monomer and trimer model compounds in an attempt to gain some insight into the possible origin of the γ-relaxation process which occurs in these polymers...
The mechanical relaxation spectra of co-extruded linear low-density polyethylene (LLDPE) films, prepared from copolymers of ethylene and 1-octene, were measured in parallel and transverse directions to the processing orientation. Both the γ- and β-relaxations do not show a noticeable dependence on the direction in which the measurements were performed. However, whereas the α-relaxation in the measurements...
The relaxation behaviour of coextruded linear low-density polyethylene (LLDPE) films, prepared from copolymers of ethylene-1-octene, is reported. The spectra, expressed in terms of loss tan δ, present a γ relaxation of lower intensity than that exhibited for conventional low density polyethylene of the same crystallinity, followed, with increasing temperature, by a β relaxation process that appears...
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