Title :
An application of thermally stimulated current technique to molecular motion analysis of polymers
Author :
Shimizu, Hiroshi ; Kitano, Takeshi ; Nakayama, Keisuke
Author_Institution :
Nat. Inst. of Mater. & Chem. Res., Ibaraki, Japan
Abstract :
The glass transition of a liquid crystalline copolyester of p-hydroxybenzoic acid (HBA) and 2-hydroxy-6-naphthoic acid (ANA) was studied by the thermally stimulated depolarization current (TSDC) and the thermal sampling (TS)-TSDC methods. The poling temperature (Tp) dependence of global TSDC spectra revealed the existence of the sub-Tg relaxation which was responsible for the apparent broadening of the glass transition of this copolyester. The TS-TSDC spectra also revealed that the temperature dependence of the relaxation times in both the sub-Tg and α relaxations was ruled by the same compensation temperature (Tc). The physical meaning of Tc was discussed in relation to the thermal-expansion coefficient
Keywords :
compensation; dielectric polarisation; dielectric relaxation; glass transition; liquid crystal polymers; molecular reorientation; polymer blends; thermal expansion; thermally stimulated currents; α relaxation; compensation temperature; glass transition; glass transition broadening; global TSDC spectra; liquid crystalline copolyester; molecular motion analysis; p-hydroxybenzoic acid 2-hydroxy-6-naphthoic acid copolyester; poling temperature dependence; relaxation times; temperature dependence; thermal sampling-TSDC method; thermal-expansion coefficient; thermally stimulated current technique; thermally stimulated depolarization current; Chemical analysis; Cooling; Crystalline materials; Crystallization; Glass; Liquid crystal polymers; Motion analysis; Polarization; Sampling methods; Temperature dependence;
Conference_Titel :
Electrets, 1996. (ISE 9), 9th International Symposium on
Conference_Location :
Shanghai
Print_ISBN :
0-7803-2695-4
DOI :
10.1109/ISE.1996.578158
