Graft Copolymerization of 4-Vinylpyridine Onto Modified Cellulosic Fibers. the Ceric Ion Concentration Effect

Abstract

The graft copolymerization of 4-vinylpyridine was carried out on mercerized cellulose and partially carboxymethylated cellulose (PCMC) using ceric ammonium nitrate (CAN) as the initiator. The grafting parameters (grafting efficiency (GE), graft yield (G), and total conversion (C,)) were studied as a function of CAN concentration. It was shown that by increasing the CAN concentration, G and C, reached a maximum. The graft yields for PCMC were significantly higher than those for mercerized cellulose. The largest GE values appeared for PCMC and mercerized cellulose at low and high CAN concentrations, respectively. The Ce(1V) consumption during grafting increased with rising concentration of CAN, and it was greater in the case of PCMC than of mercerized cellulose. After acid hydrolysis of the polysaccharide backbone, the average molecular weight of grafts was determined viscometrically. Molecular weight decreased with initiator concentration. Graft frequency ( G o , on the other hand, increased with CAN concentration. GF for PCMC was higher than that for mercerized cellulose.Ce(1V) consumption increased with CAN concentration and it was lower for mercerized cellulose than that consumed during grafting on PCMC. After that, the effect of CAN concentration on the graft copolymerization onto PCMC was examined while the total nitrate ion concentration was maintained constant at 1.59M by addition of sodium nitrate. Maximum G, C,, and Ce(1V) consumption were higher than in the previous case. 41 3