Artículos de revistas
Effect of polyol excess on the electrical property of vegetable-polyurethane film
Fecha
2008-08-01Registro en:
Journal of Materials Science. New York: Springer, v. 43, n. 16, p. 5436-5440, 2008.
0022-2461
10.1007/s10853-008-2843-3
WOS:000258573900003
4802713321439692
0607115205166943
0896348165708140
Autor
Universidade Estadual Paulista (Unesp)
Universidade de São Paulo (USP)
Institución
Resumen
Freestanding castor oil-based polyurethane (PU) film was obtained using spin-coating method. The effect of polyol content was analysed by means of thermally stimulated depolarisation current and AC dielectric measurements techniques. Two relaxation peaks were observed in the temperature range of -40 to 60 degrees C for PU with different polyol contents. The presence of polyol excess provides a shift to lower temperature of the a relaxation and the decrease in the activation energy of the transition in this region might be attributed to the plasticising effect of the polyol. The peak at higher temperature is due to the Maxwell-Wagner-Sillars relaxation, which also shifts in the low temperature direction as the polyol content is increased.