HYDROLYSIS OF POLY(ACRYLAMIDE)-STARCH GRAFT COPOLYMER

Poly(acrylamide)-starch graft copolymer was treated independently with sodium hydroxide and different acid solutions. The different acids in clude phosphoric, hydrochloric, and sulphuric acid. The treatment was carried out under a variety of conditions including sodium hydroxide c oncentration, time, and duration of hydrolysis as well as type of acid used. The extent of hydrolysis was assessed by estimating amide and c arboxyl content as well as the acrylate and starch content before and after treatment. It was found that the increment in carboxyl content i s equal to the decrement in amide on using sodium hydroxide concentrat ion up to 1N, while using higher concentration than 1N leads to a diff erence in formed carboxyl and decreased amide groups. The magnitude of this difference depends on sodium hydroxide concentration as well as temperature and duration of hydrolysis. The maximum value of carboxyl content obtained was 593 meg/100 g sample. The acidic treatment of the starch copolymer does not affect the conversion of amide groups to ca rboxyl groups, and the sole effect was hydrolysis of starch component of the copolymer. Evaluation of the alkali-treated copolymer as cation exchanger was carried out. The absorption efficiency % of different c ations depends on the associated anions and follow the order: Cu2+ Zn2 + > Co2+ > Mg2+. (C) 1995 John Wiley & Sons, Inc.