Graft copolymerization of acrylonitrile on kenaf fibers by ceric ion in the presence of allyl compounds

Abstract

Graft copolymers of acrylonitrile on kenaf fibers were obtained in an aqueous medium by the use of allyl alcohol and allyl chloride in combination with ceric ion as redox pairs. The graft copolymerization reactions showed distinct features that were associated with different initiating species derived from the redox pairs. For a cericallyl-chloride-initiated reaction, a minimum graft yield was observed, accompanied by an enhanced graft yield. This suggested the existence of two kinetically controlled grafting reactions arising from two different initiating species. For the ceric-allyl-alcohol-initiated reaction, the grafting profile showed a maximum yield and suggested the presence of one active initiating species. High concentrations of acrylonitrile were favorable to grafting with values of up to 150%, but they also resulted in decreased efficiency in monomer conversion to grafted polymer. The frequency of grafting increased with the concentration of allyl alcohol but the molecular weight of grafted polymer of up to 4.46 x 10 4 decreased by a factor of one and half over the concentration range 1.8-9.0 x 10 -4 M of the latter. The presence of 10% (v/v) N,N'-dimethylformamide resulted in zero graft, but the same vol % of formic acid had no apparent effect on the graft yield. A negative temperature dependence in the graft yield was found in the temperature range of 50-70°C.