Grafting of acrylonitrile on cellulose xanthate

AbstractA study has been made of the grafting of acrylonitrile onto a bleached kraft pulp by application of the xanthate method developed by Faessinger and Conte. Acrylonitrile was grafted to the cellulose in aqueous suspension at 25°C, with cellulose xanthates of gamma numbers from 3 to 13. The reaction system contained 1–2 percent xanthogenated pulp, 0.2–0.9 mole/1. hydrogen peroxide, 0.45–1.0 mole/1. acrylonitrile, and the reaction time was 45 min. In some cases 0.6–60 mmole/1. sulfuric acid was added to the reaction system. The grafting yield was calculated from the nitrogen content of the grafts. The degree of polymerization (DP) of the grafted polyacrylonitrile, after hydrolytic removal of the cellulose, was calculated from the limiting viscosity number of dimethylformamide solutions of the polymer at 25°C, and use of the formula [ε] = 2.43 × 10−4 (M)0.75. The grafts were found to contain 10–35 percent polymer of DP = 350–1000, and an average number of 1–4 grafted polymer chains per cellulose chain, i.e., less than 5 percent of the number of xanthate groups initially present in the cellulose xanthate. The number of grafted polymer chains was dependent upon the pH, and the DP of the grafted polymer was dependent upon the monomer and xanthate concentrations; the higher the monomer concentration was, and the lower the xanthate concentration was, the higher it became. Possible mechanisms for grafting are discussed.