1H and 19F ENDOR of carbon black-polymer composites

Abstract

1H and 19F electron-nuclear double resonance (ENDOR) spectra have been obtained for some carbon blacks carbon black-polymer composites, at temperatures ranging from 130 to 350 K. The ENDOR spectra are sensitive to the nature of the carbon black surface, the carbon black-polymer interface in the composites. In the carbon blacks D 2O exchange shows that approximately one-half of the 1H ENDOR signal arises from acidic protons accessible to the carbon black surface. In the composites, the contribution of the polymer 1H nuclei to the ENDOR signal is much larger than that from the carbon black. In addition, 19F nuclei in the polymer can also give rise to an ENDOR signal. The 1H 19F ENDOR signals are a novel probe of the orientation motion of the polymer at the polymer-carbon black interface, show a marked dependence on the physical properties of the composite, including the glass transition temperature, the ratio of fluorine to hydrogen in the polymer, prior heat or mechanical treatment.