The effect of phenol/formaldehyde ratio on the char yield from phenolic resins

Abstract

Abstract An idealized mechanism for the carbonization of phenolic resins was adopted and an equation was derived for the char yield. In simplified cases this was shown to be a function giving a maximum of 67.9% at a 1:1 formaldehyde/phenol molar ratio, falling rapidly at lower and slowly at higher ratios. In experimental verification, the alkalicatalyzed reaction of phenol and formaldehyde at various molar ratios was studied and the resulting resins were characterized and carbonized. The char yields were found to correspond well with predictions, with a maximum of about 67.2% in the region of 1.1:1 formaldehyde/phenol molar ratio.