The effect of the chain structure of carboxylated polypropylene carrier (polypropylene grafted with unsaturated carboxylic acid) on the polymerization rate of acrylonitrile was investigated. The comparison on the initiation activity of vanadyl polycarboxylate (polymer supported catalyst) with vanadyl iso-butyrate (low molecular homologue) and vanadyl sulfa-te (low molecular non-homologue) was made. The experimental results indicated that (1) the cooperation effect exists between the carboxyl groups of (P-COO)2 VO;(2) the chain ef-fect of carrier enhances the cooperation effectof carboxyl groups; (3) the polymerization rate was affected by the d-1-configuration of the chains of polycarboxylic acid

the distance of car-boxyl groups and the mass transfer effect of carrier and (4) under our experimental condi-tions

the mechanism of initiation does not depend upon the chain structure of polymer sup-porters.