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

Compensation has been reported for the relaxation parameters: the activation energy W and the pre-exponential factor τ0, determined from the Thermal Sampling of Thermally Stimulated Depolarization Current technique. Below the glass transition it is assumed that the relaxation time follows an Arrhenius equation. In the vicinity of glass transition temperature an experimental thermogram may be analyzed using the Vogel-Fulcher-Tamman-Hesse (VFTH) or the Williams- Landel -Ferry equation. In this article we use the VFTH relationship to study the compensation effect in the range of glass transition. For an elementary peak obtained by TS there is a relationship between the activation energy W, the temperature of the maximum current Tm, the VFTH temperature, the compensation temperature Tc and the compensation time τ c. We employ this relationship for a basic analysis of the compensation effect in the temperature range around Tg. By numerical simulations, and assuming parameters similar to those measured experimentally, we show that it is possible to observe a compensation point in some well defined conditions

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Relaxation of New-Tpi Thermoplastic Polyimide Studied by Thermally Stimulated Depolarization Current

MRS Proceedings ◽

10.1557/proc-321-197 ◽

1993 ◽

Vol 321 ◽

Author(s):

Sharon X. Lu ◽

Wendy C. Russell ◽

Peggy Cebe

Keyword(s):

Tensile Strength ◽

Glass Transition ◽

Monomer Unit ◽

Amorphous Material ◽

High Tensile Strength ◽

Depolarization Current ◽

Aromatic Polyimide ◽

The Subject ◽

Thermally Stimulated Depolarization ◽

Group 1

Semicrystalline polyimide, Regulus™ NEW-TPI, is a thermoplastic polyimide produced by mitsui Toatsu. This aromatic polyimide possesses outstanding heat resistance, high tensile strength, excellent electrical properties, and strong solvent resistance. It has become the subject of recent study in our group [1–6] and others [7–13]. The flexible ether and meta linkages in the monomer unit lower its glass transition temperature (Tg) to 250°C in quenched amorphous material.

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The study of glass transition in epoxy resin using thermally stimulated depolarization current measurements

Polymer ◽

10.1016/0032-3861(91)90183-j ◽

1991 ◽

Vol 32 (16) ◽

pp. 2892-2897 ◽

Cited By ~ 15

Author(s):

M. Topić ◽

A. Moguš-Milanković ◽

Z. Katović

Keyword(s):

Glass Transition ◽

Epoxy Resin ◽

Depolarization Current ◽

Thermally Stimulated Depolarization Current ◽

Thermally Stimulated Depolarization

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Investigation of Dipolar Relaxation Processes in a Side-Chain Nonlinear Optical Polymer

MRS Proceedings ◽

10.1557/proc-446-97 ◽

1996 ◽

Vol 446 ◽

Cited By ~ 1

Author(s):

Z. -Y. Cheng ◽

R. S. Katiyar ◽

S. Bauer ◽

S. Bauer-Gogonea

Keyword(s):

Glass Transition ◽

Dielectric Spectroscopy ◽

Nonlinear Optical ◽

Side Chain ◽

Relaxation Processes ◽

Dipolar Relaxation ◽

Depolarization Current ◽

Chain Polymer ◽

Optical Polymer ◽

Nonlinear Optical Polymer

AbstractAmorphous thin films of a typical side-chain nonlinear optical polymer were investigated by means of dielectric spectroscopy and thermally stimulated depolarization current (TSDC) within the temperature range -40°C to 230°C. Three distinct relaxation processes, labelled α, β and γ were observed. The α-relaxation, associated with the glass transition, is well described by the Vogel-Fulcher relation, while the sub glass transition β and γ-relaxation follow Arrhenius relations. The advantage of TSDC over dielectric spectroscopy is demonstrated for the investigation of the weak β-relaxation in the side-chain polymer. Furthermore, the β -relaxation is responsible for the initial, fast decay of the electro-optical response of the side-chain polymer at room temperature.

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