Cerium‐initiated grafting of acrylonitrile onto cellulosic materials

Grafting of acrylonitrile onto native cotton, swollen cotton, viscose, ramie, and hydrocellulose was studied with tetravalent cerium as initiator. The effect of temperature on the graft yields is examined. With ceric ammonium nitrate the grafting yields are found to be higher at 20 and 40 than at 60°C. Ceric ammonium sulfate, on the other hand, produces more grafting at 60 than at 20 and 40°C. The consumption of ceric ions is less, whereas the per cent graft yields are higher for the swollen cottons and viscose than for native cotton. Graft yields are shown to be related to substrate accessibility if the grafting reaction is carried out under conditions that suppress homopolymerization. Oxidation of these celluloses with Ce IV has also been studied. It is found that more Ce IV is consumed during grafting than during oxidation of cellulose under identical reaction conditions. Excess Ce IV consumed in the grafting reaction has been shown to be directly related to extent of homopolymerization, which accompanies grafting. Some data on the storage stability of the free‐radical activity produced by oxidation of cellulose with Ce IV are also reported. It is observed that the cerium‐oxidized samples can initiate graft poly merization even after 4–5 hr. if stored in nitrogen.