Copolymer Ultra-high Molecular Weight Polyacrylamide

Hydrolysed polyacrylamide with a super-high molecular weight suitable for driving crude oil in reservoir is prepared by copolymerization of acrylamide and sodium acrylate. In this technology, firstly, sodium acrylate is prepared by neutralization of acrylic acid and sodium hydroxide, then, copolymer of acrylamide and sodium acrylate is synthesized in aqueous solution. In this article, the factors that affect molecular weight and solubility of polyacrylamide are studied and suitable initiator system is selected. The optimum parameters of copolymerizing process are obtained as follows: the molar proportion of acrylamide and sodium acrylate is 7:3, the monomer concentration is 30%, pH value of solution is 12, the oxidizer (K2S2O8) concentration is 0.1%, the reducing agent (NH2CONH2) concentration is 1%, the chain-transfer agent concentration is 0.4%. The initial reaction temperature is 35℃. After comonomers react in the obturator for 2.5 hours, reaction temperature is hoisted to 55℃. The relationship between the weight of sodium acrylate (NaAA) and hydrolytic degree (HD) of copolymer is studied. The equation is obtained as follows: HD=0. 9723NaAA+0. 951. The super-high molecular weight polyacrylamide is obtained by using the process, withintrinsicviscosity ([77]) 25dl/g, molecular weight 2X107, hydrolytic degree can be adjusted ,soluble time less than 35min.