Enhancing the performance of paper via enzyme-modified starch surface sizing and selection of optimal enzyme system.

The application of enzyme-modified starch in surface sizing provides an effective strategy to improve paper performance. However, the effects of different enzyme-treated starch-based sizing agents on various paper properties have not been thoroughly investigated. In this study, tapioca starch was modified using various enzymes (i.e., α-amylase, β-amylase, type II pullulanase, and glucoamylase), and subsequently applied in paper surface sizing. The quality of starch-based sizing agents and the various properties of the papers were comprehensively evaluated and analyzed. In addition, the effects of different enzymes on the multiscale structure of starch were investigated to validate the effectiveness of enzymatic treatment. The results demonstrated that enzyme treatment significantly improved the quality of the starch-based sizing agents. Particularly, the type II pullulanase-modified starch-based sizing agent exhibited the best viscosity stability, and the paper sized with this agent (TSP-P) showed superior surface properties, thermal stability, and various mechanical strengths. Compared to the unsized paper, the surface strength and tensile strength of TSP-P increased significantly by 119.8 % and 40.1 %, respectively. Therefore, in comparison with α-amylase, β-amylase, and glucoamylase, type II pullulanase shows greater potential for application in starch-based surface sizing agents.