Molecular weight characterization of poly(acrylamide‐co‐sodium acrylate). I. Viscometry

Abstract Mark–Houwink constants for polyacrylamide and poly(acrylamide‐ co ‐sodium acrylate) in 0.2M Na 2 SO 4 were measured using eight fractionated samples of polyacrylamide and 26 hydrolyzed polyacrylamide samples. The dependence of K and a on the copolymer compositions was found for the range of acrylate content 6 ∼ 40 mol %. A relationship between intrinsic viscosity and acrylate content in the form of square root law was found. Molecular weights of copolymer samples with various compositions were estimated using viscometry with Mark–Houwink equations established in this work. The molecular weights of narrow MWD copolymer samples could be measured with an error of ±5%, whereas those of broad MWD copolymer samples with an error of ±8%.