The microstructure and morphology of carbon black: A study using small angle neutron scattering and contrast variation

Abstract

This is a study of the form and structure of particles and particle aggregates of an experimental high surface area carbon black (HSA) using small-angle neutron scattering and the method of contrast variation. Contrast variation was effected by studying suspensions of the carbon black in cyclohexane containing different fractions of deuterocyclohexane. We find that the approximately 29 nm diameter USA particles are arranged as small, linear aggregates with an average aggregation number between 4 and 6. The structure averaged over the particle population is best represented by a prolate ellipsoid of revolution with semiaxes 14.5 and 76.4 nm. The surface of the aggregates appears smooth over length scales larger than 1 nm, which places an upper limit on the surface roughness observed by other methods. The internal structure of the aggregates is described by a shell-core model, with the shell density being consistent with a graphitic structure and the core being of lower density, more like amorphous carbon. Some fraction of the core volume (0.1 to 0.2) is taken up by voids that are not accessible to the solvent. An estimate of the shell thickness gives 1 to 2 nm along the ellipsoid minor axis and 6 to 10 nm along the major axis. The particles of the aggregate appear to be fused so that the less dense amorphous core is continuous through the inner parts of the aggregate. The information that can be obtained on the internal structure using contrast variation is limited by heterogeneity in the chemical composition of carbon black aggregates.

Size and shape of crystallites and internal stresses in carbon blacks

“…The figure shows that the graphitization heat treatment shifts f(x) to considerably higher size values and due to this heat treatment the size distribution function becomes very narrow. The increase of the grain size of carbon blacks due to graphitization has been observed before by Raman, TEM, AFM, and also by X-ray diffraction using the Scherrer method [9][10][11]. These techniques proved that at elevated temperatures crystallites grow both in the lateral and vertical directions.…”

“…Energies of adsorption of different adsorption sites and their relative populations have recently been evaluated by gas adsorption technique [8]. The sizes of graphitic crystallites have been estimated from X-ray diffraction [5,9], neutron scattering [10], Atomic Force Microscopy [11], and Raman spectroscopy measurements [3][4][5]. Those studies showed that the average size of crystallites, L a , is similar for all commercial carbon black grades produced in furnace reactors and roughly equal 2.3 nm.…”

Measurement of Porosity in a Composite High Explosive as a Function of Pressing Conditions by Ultra‐Small‐Angle Neutron Scattering with Contrast Variation

“…With this method, D1 is systematically varied with the introduction of a deuterated fluid or the isotopic substitution of deuterium for hydrogen in one of the components. Deuterium has a very different scattering length than hydrogen, so by varying the amount of deuterium present, different structural features can be emphasized (or deemphasized) [8,10,16].…”

The influence of the chemically bonded interface between fillers and binder on the failure behaviour of an epoxy coating under marine alternating hydrostatic pressure

“…Liu et al [4] compared the failure behaviour of nano-SiO 2 fillers epoxy coating under hydrostatic pressure with that under atmospheric pressure, the results indicated that high hydrostatic pressure accelerated the failure of organic coating by promoting diffusion of water in the coating. They also [5] considered that both physical and chemical properties between inorganic fillers and organic binder contribute to a bad interfacial compatibility [13]. Our previous studies indicated that a large number of defects on the coating surface such as pores were generated by the addition of inorganic fillers [4][5][6].…”