Grafting acrylonitrile onto wood pulp: Influence of process variables



Graft polymerization of acrylonitrile onto a never-dried bleached kraft pulp by the ceric ion process was not affected by the presence of air, nor by the use of technical-grade ceric salt and unpurified monomer. The initial polymerization rate and final degree of conversion to grafted polymer increased with monomer and pulp concentration. An increase in the catalyst concentration also increased the initial rate and final conversion up to a maximum value, after which they leveled off. The amount of catalyst required for a given degree of conversion was minimized when operating at high concentration of pulp and monomer and when the catalyst was added last. Attainable graft level decreased when the pulp was dried but could be brought back to its normal level after the dried pulp was beaten. The molecular weight of the polymer increased with monomer concentration but was independent of ceric salt concentration when the latter was low. The number of grafted sites increased with ceric salt concentration.