Electron spin resonance in neutron irradiated graphitized carbon black

Abstract The number of unpaired electrons in several rubber-reinforcing blacks has been determined by quantitative electron spin resonance assay. The odd electron concentrations are of the order of 1019 to 1020 spins/gram. These concentrations are consistent with the negative (diamagnetic) net magnetic susceptibility of the blacks. Oxygen and other paramagnetic substances, even in extremely minute quantities, exert a powerful influence on the electron spin resonance observed. Their effect is to broaden the resonance line and this reduces considerably the signal intensity. In extreme cases the intensity may be reduced to the noise level ; in less severe instances the broadening may lead to erroneously low spin assays. Carbon blacks differ in their susceptibility toward line broadening effects. Evidence is presented for a correlation between the odd electron concentration of carbon blacks and the modulus they impart to rubber, suggesting a combination reaction between the carbon black radicals and polymeric free radicals formed during processing or vulcanization. The possibility of such a reaction is supported by electron spin resonance measurements on carbon blacks heated in the presence of rubber, both with and without curatives. On the basis of the results available it is not possible to ascertain the full importance of the odd electrons of carbon black in elastomer reinforcement. It is certain that the unpaired electrons are not necessary for the development of reinforcement effects in general, although they may increase them substantially by providing an additional interaction mechanism for the union of black and rubber.

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An electron spin resonance investigation of carbon black-filled polybutadiene

Journal of Materials Science ◽

10.1007/bf00561973 ◽

1977 ◽

Vol 12 (10) ◽

pp. 2011-2020 ◽

Cited By ~ 19

Author(s):

E. M. Cashell ◽

V. J. McBrierty

Keyword(s):

Electron Spin Resonance ◽

Carbon Black ◽

Electron Spin ◽

Resonance Investigation ◽

Spin Resonance ◽

Electron Spin Resonance Investigation

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A Preparation of High Resolution Standards for Electron Microscopy. Part II

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064852 ◽

1971 ◽

Vol 29 ◽

pp. 160-161

Author(s):

Akira Tanaka ◽

David F. Harling

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Carbon Black ◽

Single Crystal ◽

Dark Field ◽

Graphitized Carbon Black ◽

Graphitized Carbon ◽

Dark Field Imaging ◽

Crystal Films ◽

Micro Holes

In the previous paper, the author reported on a technique for preparing vapor-deposited single crystal films as high resolution standards for electron microscopy. The present paper is intended to describe the preparation of several high resolution standards for dark field microscopy and also to mention some results obtained from these studies. Three preparations were used initially: 1.) Graphitized carbon black, 2.) Epitaxially grown particles of different metals prepared by vapor deposition, and 3.) Particles grown epitaxially on the edge of micro-holes formed in a gold single crystal film.The authors successfully obtained dark field micrographs demonstrating the 3.4Å lattice spacing of graphitized carbon black and the Au single crystal (111) lattice of 2.35Å. The latter spacing is especially suitable for dark field imaging because of its preparation, as in 3.), above. After the deposited film of Au (001) orientation is prepared at 400°C the substrate temperature is raised, resulting in the formation of many square micro-holes caused by partial evaporation of the Au film.

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