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By using non-graphitizable and graphitizable carbons prepared from poly(furfulyl alcohol) and poly(vinyl chloride), respectively, an attempt is made to determine the number of carbon edge sites by analyzing their hydrogen content and the amounts of surface oxygen complexes and localized spins. It is found that, at the present preparation conditions, the number of hydrogen-terminated edges is much higher than the number of surface oxygen complexes regardless of the type of carbon and the heat-treatment temperature, but the contribution of the localized spins derived from σ free radicals in closed spaces and/or triplet carbene/carbyne species may become comparable to the hydrogen content when the heat-treatment temperature is higher. Moreover, the average sizes of graphene layers in these carbons are estimated from the total number of edge sites. This analysis suggests that the actual size in the poly(furfulyl alcohol)-derived carbons is much larger than the size detected with transmission electron microscopy. This large difference is discussed in relation to a real structure of graphene layers in non-graphitizable carbons. [ABSTRACT FROM AUTHOR]

Abstract: A technique to determine a trace amount of hydrogen in carbon materials heat-treated above 1000°C was developed. Three types of carbons prepared from poly(furfulyl alcohol), poly(vinyl chloride) and mesophase carbon microbeads were heat-treated at various temperatures ranging from 1000 to 1800°C. Then they were gasified by O2 in a fixed bed flow reactor, and the H2O gases formed during the gasification processes were carefully monitored with a Karl Fischer moisture analyzer. As a result, this method makes it possible to determine the hydrogen contents in the carbons down to three places of decimals as a weight percent and can detect even a trace amount of hydrogen as low as 0.002wt.%. A possible chemical structure of carbon edge sites was also discussed based on the experimentally determined hydrogen contents. [Copyright &y& Elsevier]

The purpose of the present study is to provide insight into the structure of “bound rubber”, which is responsible for the reinforcing effect of carbon black (CB) in a rubber composite. When styrene-butadiene rubber (SBR)-CB composites were treated with toluene at a high temperature (150 °C) in an autoclave (AC) vessel, it was found that the AC treatment extracted a much larger amount of physisorbed rubber than the conventional Soxhlet extraction. Moreover, the pulsed 1 H NMR technique reveals that the AC treatment can extract almost all of “loosely bound rubber” but leave “tightly bound rubber”. An attempt was then made to correlate the amount of tightly bound rubber with the carbon surface chemistry in CB. As a result, a good linear relationship was found between the amount of tightly bound rubber and the hydrogen content of CB among four SBR composites with different types of CBs. Based on the above linear relationship, the origin of the tightly bound rubber is discussed in terms of the nature of the interaction (chemical and physical) between the rubber polymer chains and the CB surface. [ABSTRACT FROM AUTHOR]