The storage and its stability of space charge in poly(ethylene naphthalene-2, 6-dicarboxylate)

Poly(ethylene naphthalene-2,6-dicarboxylate) (PEN) is an aromatic polyester with molecular structure similar to that of poly(ethylene terephthalate)(PET). In this paper, the space charge storage ability and its stability in corona charged PEN were studied by measurement of surface potential decay under different storage conditions including dif- ferent temperatures and relative humidities, and analysis of open circuit thermally stimu- lated discharge (TSD) current spectra and charge TSD curves. The comparison between the charge stability of PEN and PET was carried out. The results point out that the charge stability of PEN is markedly better than that of PET under different environmental condi- tions. By means of isothermal depolarization program, the space charge lifetimes (effec- tive time constant) τ at room temperature of positively and negatively charged PEN are estimated to be 90 y. The results offer theoretical and technical support for the use of PEN as the chip of high quality electret condenser microphone due to its excellent dielectric, mechanical and thermal properties.