The positive temperature coefficient phenomenon of vinyl polymer/CB composites
Article first published online: 10 MAR 2003
Copyright © 1993 John Wiley & Sons, Inc.
Journal of Applied Polymer Science
Volume 48, Issue 10, pages 1795–1800, 10 June 1993
How to Cite
Tang, H., Piao, J., Chen, X., Luo, Y. and Li, S. (1993), The positive temperature coefficient phenomenon of vinyl polymer/CB composites. J. Appl. Polym. Sci., 48: 1795–1800. doi: 10.1002/app.1993.070481013
- Issue published online: 10 MAR 2003
- Article first published online: 10 MAR 2003
- Manuscript Accepted: 14 SEP 1992
- Manuscript Received: 18 FEB 1992
In this paper, the results of a systematic study of carbon black (CB)-filled conducting polymer positive and negative temperature coefficient (PTC/NTC) effects are report. The conductivity of the composites jumps by several orders of magnitude at the critical value of carbon black. This critical value, øc, decreases with the increase of melt index and degree of crystallinity of the polymer. The crystalline lamellae just “modify” the distribution of carbon black and make the dispersion heterogeneous. Radiation cross-linking enhances the PTC intensity and decreases the NTC effect of the materials. The electrical reproducibility of compounds is improved by the cross-linking structure that reduces the freedom of carbon black movement at high temperature. The NTC phenomenon is related to the carbon black coagulation that facilitates electrical conduction at high temperature. The larger the melt index, the more easily carbon black coagulates. A new model was set up to explain the results successfully. © 1993 John Wiley & Sons, Inc.