Synthesis of Cationic Xylan Derivatives and Application as Strengthening Agents in Papermaking

Cationic xylan derivatives were prepared by etherification using 3-chloro-2-hydroxypropyltrimethylammonium chloride as the cationic reagent under an alkaline condition. These derivatives were utilized as strengthening agents to enhance the mechanical strength properties of paper. Cationic xylan derivatives with different degree of substitution (DS) values (0.11 to 0.35) that corresponded to different cationic charge densities (0.51 mmol/g to 0.85 mmol/g) were successfully synthesized, and the reaction parameters were optimized based on the DS and charge density. The cationic xylan derivatives were characterized by means of elemental analysis, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectrometry. The xylan derivatives had a good performance in strengthening the physical properties of the paper, such as the tensile, tear, and burst strengths. When the DS of the cationic xylan derivative was higher, the strengthening effectiveness was better. At a 2.4-wt.% (based on dried pulp) dosage with the xylan derivative that had a DS of 0.32, the tensile, tear, and burst indices of the pulp increased by 63%, 58%, and 42%, respectively. For the pulps with different beating degrees, the cationic xylan derivative was more beneficial to the pulps with a lower beating degree.