Comparative study of carbon dioxide and nitrogen atmospheric effects on the chemical structure changes during pyrolysis of phenol-formaldehyde spheres

The effect of CO(2) atmosphere on the chemical structure changes of resol-type phenol-formaldehyde spheres during pyrolysis was investigated, in comparison with that of N(2) atmosphere, using FT-IR, TGA, and elemental analysis techniques. It was found that, in contrast to the expectation that CO(2) may act as an oxidizing agent at high temperature, it behaves very similar to N(2) during pyrolysis of PF spheres up to 700 degree C, but results in a somewhat different extent of some specific reactions. That is, although the reactions occurring up to 700 degree C were dominated by crosslinking and/or polyaromatization under both CO(2) and N(2) atmospheres, fewer alkyl-phenolic ether bonds were formed under CO(2) than under N(2). As a consequence, the samples carbonized under CO(2) at 700 degree C were found to have more pendant groups on the edge carbon atoms of carbon in the carbonized samples than those prepared under N(2) atmosphere.