Properties and applications of lignin–acrylamide graft copolymer

Abstract

Free-radical, graft polymerization of acrylamide onto lignin occurs in photolysed, distilled dioxane containing calcium chloride and trace quantities of ceric ion. The yield of the reaction is controlled by the amount of oxygen present during dioxane photolysis, the duration of photolysis, and the amount of calcium chloride in the reaction mixture. Polyacrylamide homopolymer is formed during the reaction and can be removed from the graft copolymer by base dialysis. Side chains of the reaction product can be hydrolyzed to partially hydrolyzed polyacrylamide by solution in aqueous base. Hydrolysis raises the limiting viscosity number of the product by a factor of up to 47. As a drilling mud additive, the ability of the reaction product to lower yield point, lower gel strength, or lower API filtrate volume increases with increasing degree of hydrolysis.