Cross‐linked cationic polyvinyl alcohol for improving mechanical strength of paper

Abstract Cross‐linked cationic polyvinyl alcohol (CPVA) is obtained by solution polymerization using vinyl acetate (VAc) and N‐(isobutoxymethyl)acrylamide (IBMA) as main raw materials and free radical co‐polymerization using glycidyl methacrylate (GMA) and dimethylaminoethyl methacrylate (DM) as modified monomers. The structure is characterized by HNMR. The effects of DM monomer on the properties of CPVA are investigated. It turns out that CPVA dispersion is a Bingham fluid with good stability. The particle size of CPVA reaches minimum and the value is 147.2 nm, which is in favor of infiltration into the paper. It is more suitable for the DM dosage ranging from 2% to 2.5% in light of the mechanical properties of CPVA film. The obtained CPVA is amorphous and the degree of crystallinity is decreased. When used as surface sizing agent for paper, the water absorption of the sizing paper reaches minimum and the folding resistance reaches maximum when DM is 2.5%. The maximum dry and wet tensile indexes of the paper are increased by 190.71% and 331.09%, respectively. SEM results shows that the larger pores between the paper fibers are filled and cross‐linked after CPVA sizing, which is beneficial to the improvement of paper strength.