The polymerization of acrylarmde in the presence of coal humic acids was studies with dilatometry
which was carried out in aqueous solution at 60℃ with potassium-peraulfate as sole initiator. Humic acids lengthen induction period and depress rate of polymerization. These influences are pH dependent. The effect is supposed to be concerned with stable free radical
quinone. phenol functional groups wish exist in humic acids.