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Dielectric behavior of epoxy resin during cure: A vector voltage study
Author(s) -
Lee SungNung,
Liao YunnHsin,
Huang PiengTsung,
Lee JunLung
Publication year - 1990
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760300405
Subject(s) - materials science , dielectric , epoxy , composite material , conductance , dipole , electrode , capacitance , matrix (chemical analysis) , analytical chemistry (journal) , chemistry , condensed matter physics , physics , organic chemistry , optoelectronics
Vector voltage ( Vc ), measured across a plate electrode filled with resin, is a function of the resin matrix structure. The variation of Vc during the cure process at various frequencies was studied. A peak with minimum Vc value was observed. It was found that the initial stage of heating is mainly a temperature equilibrating step, where the viscosity decreased to a minimum owing to the rapid alignment of the dipole (and ion) species. Vc then ascended as the major cure reaction took place, as the mobilities of the electrical species were lowered in the rather tight matrix structure of the partially cured resin. The quantity of bound charge is an indicator of dipolar and ionic movements within the resin matrix, and was employed to describe the trajectory of the Vc curve. Bound charge conductance was also found to be the dominating factor in the Vc variation when tests were carried out in a low frequency AC field; whereas free charge conductance became more important for tests at high frequency. It was also observed that the cure phenomenon was not detectable from the Vc variation when monitored with an AC frequency of 38 kHz or higher.