Phenomenological Model to Describe the Glass Transition Relaxation Peaks for Depolarization Current Experiments

Puma, M.

doi:10.1002/(sici)1099-1581(199701)8:1<39::aid-pat612>3.0.co;2-r

Cited by 8 publications

(2 citation statements)

References 9 publications

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“…5. relaxation peak. This peak will be described by the following phenomenological expression 7 In Figure 1, the different line types represent the calculated peaks while the symbols represent the obtained experimental points. The agreement…”

Section: Description Of the Experimental Resultsmentioning

confidence: 99%

Aging effects in poly(DTH succinate) observed with thermal-stimulated polarization and depolarization experiments

Suárez¹,

Puma²

1998

J. Appl. Polym. Sci.

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Thermal-stimulated polarization and depolarization experiments with blocking electrodes are performed on a particular tyrosine-derived polyarylate: poly(DTH succinate). Aging effects on this sample are observed for the glass transition relaxation peak and the charge redistribution peak originated by the conduction though the sample when blocking electrodes are present. The high temperature region where these peaks are present is modeled, and results are presented as a function of aging time. The model describes the experimental data to better than 1% for all the aging times. Contributions between the two peaks modeled are found to be constant and independent of aging. The glass transition temperature is constant within a fraction of a degree, and the shift of the maximum temperature of the spectrum is due to the charge redistribution peak. The results obtained suggest that the variation in shape of these peaks is originated by the change in the mobility of the polymeric chains, affecting in different manners the dipole orientation mechanism, as well as conduction through the sample. A simple logarithmic aging time dependence is found for most of the parameters used in the model.

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Section: Description Of the Experimental Resultsmentioning

confidence: 99%

Aging effects in poly(DTH succinate) observed with thermal-stimulated polarization and depolarization experiments

Suárez¹,

Puma²

1998

J. Appl. Polym. Sci.

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“…To characterize the glass transition relaxation a model was used that assumes a dipolar system having been formed by permanent electric dipole moments that are fixed to the mobile polymeric chains 15. With this model using the Williams–Landel–Ferry, WLF, zero order approximation for the temperature dependence of τ ( T ), for the case where T ∼ T g or when the free volume fraction coefficient is large,16, 17 it is possible to express the thermally stimulated depolarization current as a function of T : where J 0 is the current density amplitude; β is the zero order approximation near the glass transition temperature of the WLF, T g is the measured glass transition temperature of the relaxation; and η includes the contribution of the dipolar energy as well as the energy from the polymeric matrix 15. To analyze the glass transition relaxation peaks obtained from the TSDC experiments with Eq.…”

Section: Methodsmentioning

confidence: 99%

The Molecular Interactions That Influence the Plasticizer Dependent Dissolution of Acrylic Polymer Films

Fadda

Hernández

Margetson

et al. 2008

Journal of Pharmaceutical Sciences

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Conductivity and high-temperature relaxation of tyrosine-derived polyarylates measured with thermal stimulated currents

Puma¹,

Suárez

Kohn

1999

J. Polym. Sci. B Polym. Phys.

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Thermal‐stimulated polarization and depolarization experiments without blocking electrodes are performed on tyrosine‐derived polyarylates with different backbone lengths. The experiments on the different samples are carried out using the same thermal history throughout the entire characterization process. The high‐temperature current rise caused by the conductivity of the samples is studied with a simple model that utilizes an approximation of the Williams–Landel–Ferry (WLF) relaxation time. The conductivity data is well reproduced except for temperatures well below the glass‐transition temperature and for small currents. The glass‐transition peak is modeled with a phenomenological expression valid near Tg, which is able to describe the glass relaxation with a minimum number of parameters. The conduction and the glass‐transition relaxation are studied versus the structural changes for the different samples. It is found that the conductivity and the glass‐transition temperature shift to lower temperatures as the methylene groups in the backbone increase. Furthermore, if the experimental data is presented as a function of the reduced temperature, the shape of the glass‐transition relaxation for the different samples is independent of the polymer backbone length. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 3504–3511, 1999

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Phenomenological Model to Describe the Glass Transition Relaxation Peaks for Depolarization Current Experiments

Cited by 8 publications

References 9 publications

Aging effects in poly(DTH succinate) observed with thermal-stimulated polarization and depolarization experiments

Aging effects in poly(DTH succinate) observed with thermal-stimulated polarization and depolarization experiments

The Molecular Interactions That Influence the Plasticizer Dependent Dissolution of Acrylic Polymer Films

Conductivity and high-temperature relaxation of tyrosine-derived polyarylates measured with thermal stimulated currents

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