DIELECTRIC-RELAXATION IN SHELLAC

被引：0

作者：

GOSWAMI, DN ^{[1
]}

WALKER, SM ^{[1
]}

机构：

[1] INDIAN LAC RES INST,DIV CHEM,RANCHI 834010,BIHAR,INDIA

来源：

JOCCA-SURFACE COATINGS INTERNATIONAL | 1994年 / 77卷 / 03期

关键词：

D O I：

暂无

中图分类号：

O69 [应用化学];

学科分类号：

081704 ;

摘要：

Dielectric relaxation in shellac, in both air-dried and baked films, are been investigated in the frequency range 12Hz - 100Hz at temperatures between 20 and 100-degrees-C. Three relaxation processes were observed. Air-dried films prepared from its solution in ethyl alcohol showed a major peak at around 80-degrees-C in the temperature profiles of conductance at 12Hz. The glass transition temperature was observed at 40-degrees-C. For shellac films baked at 200-degrees-C, the capacitance and conductance values remained almost constant up to about 120 and 100-degrees-C respectively. The glass-transition temperature was noticed at around 140-degrees-C. Conductance-temperature profiles at 100kHz showed a major peak at around 170-degrees-C. The changes observed in the dielectric properties of the baked films, compared to those of the air-dried films, were ascribed to arise due to the cross-linkages occurring in shellac at high temperatures.

引用

页码：114 / &