Preparation and characterization of crosslinked glyoxalated polyacrylamide paper-strengthening agent.

To obtain additives that could simultaneously increase the dry strength and wet strength of paper sheets, we synthesized a series of crosslinked cationic glyoxalated polyacrylamide (GPAM) resins by using acrylamide (AM), 2-methacryloxyethyl trimethyl ammonium chloride (DMC), N-methylolacrylamide (NMA), 2-mercaptoethanol, and glyoxal as the main materials. GPAM demonstrated excellent properties and had a good strengthening ability under the following polymerization conditions: dosage of AM = 55 wt %, dosage of the cationic monomer DMC = 5.5 wt %, dosage of the crosslinking monomer NMA = 8.0 wt %, dosage of chain-transfer agent 2-mercaptoethanol = 1.0 wt %, dosage of glyoxal = 30 wt %, and charge of the initiator (ammonium persulfate/sodium bisulfite = 1 : 2) = 0.5 wt %. The products were characterized by Fourier transform infrared spectroscopy, ¹H-NMR, size exclusion chromatography, and Ubbelohde viscometry. The copolymers with a viscosity-average molecular weight of approximately 26,000 and a polydispersity index of 1.460 had a much better strengthening ability. When these GPAM resins were used as paper-strengthening agents, the mechanical strength of the paper was remarkably enhanced, and the dry and wet tensile indices of the handsheets increased by 24.6 and 381%, respectively, compared with those of handsheets without GPAM. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012 [ABSTRACT FROM AUTHOR]