Crosslinking chemistry of curing carbon composites containing novolac/furfuryl alcohol resins and carbon black or mesophase pitch as additives

The crosslinking chemistry was studied for producing carbon composites using carbon black or mesophase pitch as additives and a binder containing novolac and furfuryl alcohol (FA) resins and hexamethylene tetramine (HMTA) as a crosslinker. Curing the composites to 205 °C generated FA, water and ammonia as the major volatile species released from the systems due to evaporation, condensation of FA and crosslinking reactions between the resins and HMTA, respectively. Carbon black or mesophase displayed a minimal effect on the chemical nature of the volatiles released from the curing. However, the carbon black particles, which were homogeneously distributed in the cured composite, produced a broad distribution of chemical environments and structures of the binder networks, and the chain motions of the binder were also modified. Mesophase pitch on the other hand was likely to participate in curing reactions of the resin phase and heterogeneous phase structures were detected only on a scale as small as ∼2 nm in the composite.