Grafting acrylonitrile on kenaf fibers using ceric ion-p-xylene redox pair

Polyacrylonitrile was grafted onto kenaf fibers in aqueous media by ceric ion–p‐xylene redox system. The graft yield dependence on p‐xylene concentration in the range 1.8–45.0 × 10−4M showed a minimum accompanied by an enhanced yield. This suggested the existence of two kinetically distinct grafting reactions associated with two precursor‐initiating species, a p‐xylyl radical and a diradical. The frequency of graft Fg and the average molecular weight of grafted polymer Mv were inversely related at varying concentrations of p‐xylene with values for Mv of up to 5.18 × 104. The effect of ceric ion concentration on Mv showed that the ion is nonterminating at low concentrations in the range 8.3–33.3 × 10−3M. The graft yield showed positive temperature dependence in the region of 30–40°C and a negative one at higher temperatures, resulting in a decrease in the initial rate of graft at 70°C by a factor of 8 compared to its value at 40°C. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1751–1755, 1999