PENTAVALENT VANADIUM ION-CELLULOSE THIOCARBONATE REDOX-SYSTEM INDUCEDCRAFTING OF METHYL-METHACRYLATE AND OTHER VINYL MONOMERS ONTO COTTON FABRIC

Cellulose thiocarbonate was prepared by reacting cotton cellulose fabr ic with carbon disulphide in the presence of sodium hydroxide. The tre ated fabric formed, with pentavalent vanadium ion, an effective redox system capable of initiating grafting of methyl methacrylate (MMA) and other monomers onto the cotton fabric. The dependence of grafting on vanadium concentration, pH of the polymerization medium, temperature a nd duration of grafting, nature and concentration of monomer, and solv ent/water ratio was studied. The results indicated that increasing the pentavalent vanadium (V-v) concentration up to 60 mmol/L was accompan ied by enhancement in the rate of grafting; the latter was not affecte d by further increase in V-v concentration. Maximum grafting yield was achieved at pH 2; grafting fell greatly at higher pH. The rate of gra fting followed the order: 70 degrees > 60 degrees > 50 degrees C. The graft yield increased significantly by increasing the MMA concentratio n from 0.5 to 5%. Of the solvents studied, n-propanol and isopropanol enhanced the grafting rate provided that a solvent/water ratio of 5 : 95 was used; a higher solvent ratio decreased the magnitude of graftin g. Other solvents, namely, methanol, ethanol, n-butanol, and acetone, in any proportion, decreased the rate ofproportion, decreased the rate of grafting. With the monomer used, the graft yield followed the orde r: methyl methacrylate > methyl acrylate, methacrylic acid > ethyl met hacrylate > acrylic acid. Also reported was a tentative mechanism for vinyl-graft copolymerization onto cotton fabric using cellulose thioca rbonate-V-v. (C) 1993 John Wiley and Sons, Inc.