Dielectric Relaxation Behavior of Absorbed Water on Aromatic Polyesters.

Tatsumi, Tomiwo; Ezure, Hidetoshi; Ito, Eiko

doi:10.1295/koron.49.521

Cited by 3 publications

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“…The effects of humidity have been explored for the dielectric relaxation, and it was observed that the intensity of the β relaxation increased linearly with moisture content . Similar observations have been reported on the basis of dynamic mechanical observations …”

Section: Introductionsupporting

confidence: 74%

“…18 Similar observations have been reported on the basis of dynamic mechanical observations. 19 In this paper, the effects of thermal aging on PET, poly(ethylene naphthalate) (PEN), and a series of poly-(ethylene terephthalate-co-ethylene naphthalate) (PETN) polyesters are presented. The techniques used allow comparison between the changes in the free volume and molecular relaxation processes and help to clarify some of the previously reported effects of morphology on the physical properties of these materials.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Physical Aging on the Molecular Motion and Structural Relaxation in Poly(ethylene terephthalate) and Related Polyesters

et al. 2000

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A combination of dielectric relaxation, dynamic mechanical thermal analysis, and positron annihilation measurements is reported on melt-cast films of poly(ethylene terephthalate), poly(ethylene naphthalate), and their copolymers. The effects of change in the chemical structure of the polyesters are rationalized in terms of increased restriction of the mobility of the polar segments of the chain by the incorporation of the bulky naphthalate structure. All the quenched samples exhibit physical aging when raised to elevated temperatures, the rate depending on the degree of undercooling used in the aging experiments. The free volume surprisingly does not change significantly with temperature and leads to the suggestion that the reduction in the dielectric permittivity is a consequence of a reduction in the mobility of the local segments. The increased storage modulus is also consistent with a reduction in mobility. This proposal is further confirmed by the observation of a good correlation between the rates and extents of the physical aging as detected by dynamic mechanical and dielectric relaxation measurements. Similarities in the activation energies of the β relaxation process for all the polymers investigated indicate that the dipole relaxation processes have a common origin and can be ascribed to motion of the linking polar entity. This study implies that aging is accompanied by an increase in ordering within these polyesters.

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Section: Introductionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%