Dielectric relaxation properties in polypropylene–polyurethane composites
Article first published online: 10 MAR 2003
Copyright © 1990 John Wiley & Sons, Inc.
Journal of Applied Polymer Science
Volume 40, Issue 3-4, pages 435–452, 5 - 20 August 1990
How to Cite
Bánhegyi, G., Karasz, F. E. and Petrović, Z. S. (1990), Dielectric relaxation properties in polypropylene–polyurethane composites. J. Appl. Polym. Sci., 40: 435–452. doi: 10.1002/app.1990.070400312
- Issue published online: 10 MAR 2003
- Article first published online: 10 MAR 2003
- Manuscript Accepted: 20 MAR 1989
- Manuscript Received: 13 FEB 1989
AC dielectric relaxation properties of polypropylene/polyurethane composites have been studied. The segmented polyurethane (PUR) component contained a poly(propylene oxide) soft segment, and a diphenyl methane diisocyanate/butanediol hard segment. The molecular weight of the soft segment, the concentration of the latter in the polyurethane phase, and the PUR content of the blends were changed systematically. It was observed that the polypropylene is phase-separated with respect to both PUR segments and that the dielectric relaxation properties are determined largely by the PUR component. Two transitions attributable to the glass transitions of the soft and hard phases, respectively, were observed. The soft segment transition temperature decreases with increasing molecular weight of the latter. The transition temperatures are somewhat dependent on the PUR content in the blend, indicating some interaction between the phases. Model calculations show that these shifts and some intensity anomalies are not due simply to the existence of a heterogeneous structure. The ohmic interfacial relaxation process does not play an important role in the temperature and frequency range studied.