Synthesis and Evaluation of Glyoxalated Polyacrylamide (GPAM) as a Wet and Dry-Strengthening Agent of Paper

Polyacrylamides have wide range of industrial applications as well as paper industry. They are applied mainly as clarifiers، retention and paper strengthening agents. In this research we synthesized a series of wet strength resins based on glyoxalated polyacryamide (GPAM) under different reaction conditions using acrylamide، ethylenediamine and glyoxal as the main materials and their effects on wet and dry-strength papers was investigated. The properties of the polymers were compared with the commercially available polyamideamine-epichlorohydrin (PAE) wet-strength resin. During the synthesis، the obtained products were characterized by Fourier transform infra-red spectroscopy. The tests showed that a water soluble aminated polyacrylamide (PAa) with desired storage stability could be obtained by reaction between polyacrylamide and ethylenediamine (ETD) under the conditions of 50-60°C for 24-25 h. In the next step، the synthesized GPAM under the condition of 25-30°C، 6% concentration of basic polymer containing 2. 3 mmol of amine per gram of polymer with the ratio of 0. 2 of glyoxal to base polymer showed a good strengthening ability. The obtained GPAM significantly enhanced both the dry- and wet-strength of papers. At similar application level (0. 2% of dry mass of the pulp)، synthesized GPAM provided superior wet tensile strength، dry tensile strength، burst strength and effective energy adsorption by 16%، 10%، 5% and 23%، respectively، compared to those that were achieved by commercial PAE. The combined results supported that the synthesized GPAM under suitable condition was environmentally preferred as an adsorbable organic halide (AOX) free wet-strength resin and its superior strengthening properties ensured the production of higher quality wet-strength papers.