VDF（81）／TeFE（19）共聚物的低温低频介电弛豫

Dielectric Relaxation of Low-Temperature Low-Frequency in VDF (81) / TeFE (19) Copolymer

用经过改进的介电弛豫谱仪测得不同结晶度的铁电共聚物ＶＤＦ（８１）／ＴｅＦＥ（１９）在－１２０－４０℃、１０－２－１０４ＨＺ范围内的复介电常数．低温介电弛豫过程显示室温以下共聚物的频率谱由低频和高频两部分叠合而成．低频部分符合ＷＬＦ方程，由非晶区被冻结分子链段的微布朗运动贡献；高频部分遵从Ａｒｒｈｅｎｉｕｓ规律，由晶区和非晶区分子链段较小尺度的局域运动产生．结果说明共聚物的玻璃化转变温度是－５２℃，局域弛豫活化能为３７．７ｋＪ／ｍｏｌ．

The complex dielectric constants of VDF (81) / TeFE (19) copolymers were measured over the ranges of-120-40℃ and 10-2-104Hz using an improved dieleetric relaxation spectrameter. The low-perature process of dielectric relaxation showed that the frepueney spectra of copolymers below room perature consisted of a lower frequency component ascribed to the miero-Brownian motion of molecularsegments in the noncrystalline regions, and a higher frcquency component designated as the local motions of small-scale segments. On the basis of calculated results by tile WLF equation and the Arrheniusformula, the Tg (-52℃ ) and the activation energy of local rclaxation (37.7kJ / mol) of the copolymerwere obtained.