Synthesis and characterization of modified acrylamide - pyrrolidone copolymer

Abstract

The gamma-ray induced copolymerization of partially hydrolyzed polyacrylamide (HPAM) and 1-vinyl-2-pyrrolidone was carried under various conditions. Polyacrylamide was prepared by gamma irradiation via various parameters of importance: total dose (kGy), dose rate (kGy/min) and concentration of acrylamide monomer (M). The purified polyacrylamide was subsequently hydrolyzed with aqueous solution of sodium hydroxide to convert some of the amide groups along the PAM backbone to the partially hydrolyzed polyacrylamide (HPAM). Degree of hydrolysis of the partially hydrolyzed polyacrylamide was obtained by controlling various parameters of importance: the temperature (℃), reaction time (h) and concentration of HaOH (% w/v). Infrared spectrometry was used to follow up the chemical changes of polymerization, hydrolysis and copolymerization. Degree of hydrolysis was calculated by the nitrogen content obtainable by Semi-Micro Kjeldahl Method. The highest water absortion in distilled deionized water of partially hydrolyzed polyacrylamide (HPAM)-1-vinyl-2-pyrrolidone copolymers is obtained at the total dose of 10 kGy, dose rate of 1. 19x10⁴ Gy/h, 5 g HPAM and 10 cm³ 1-vinyl-2-pyrrolidone. Higher water absorption depends on the specific extent of the degree of hydrolysis of polyacrylamide. The water absorption capacity was improved by using a freeze dryer for drying the copolymers. Water absorptions of the copolymer in deionized distilled water, sodium chloride and magnesium chloride solutions were carried out. Water absorption capacity decreased dramatically with increasing the salt concentrations and the Oxidation state of cations. Discussions of the effects of the parameters on the reaction and water absorption were also given in this research.