Graft copolymerization of vinyl monomers onto modified cottons, X. Hydrogen peroxide induced grafting of styrene onto cellulose carbamate

Abstract

AbstractGrafting of styrene onto cellulose carbamate was investigated under a variety of conditions using H2O2 as initiator. The graft yield was found to depend on the amount of carbamate groups, initiator and monomer concentrations as well as on temperature and pH of polymerization. The graft yield increased with increasing H2O2 concentration, attained a maximum at a concentration of 0.18% then fell down sharply. Maximal grafting occurred at a monomer concentration of 6.6%. The graft yield increased also by raising the polymerization temperature up to 80°C, attained maximum at 90°C then decreased significantly. With respect to pH, the graft yield decreased markedly upon increasing the pH from 2 to 4 and marginally upon further increase in pH. Addition of FeSO4 to the polymerization system caused a considerable decrement in the graft yield. A comparison between the graft yield obtained with the modified cellulose having different amounts of carbamate groups with those of the unmodified cellulose indicated that cellulose carbamates having less than 1.1% nitrogen showed lower graft yields than the unmodified cellulose. Above this, cellulose carbamate was much more amenable to grafting than the unmodified cellulose.