Starch–Citric Acid Adhesive: Preparation and Performance Study Catalyzed by p-Toluenesulfonic Acid

This study investigates the application effects of p-toluenesulfonic acid (p-TsOH) as an efficient catalyst in the esterification reaction of starch-citric acid adhesives, aiming to successfully prepare plywood with good water resistance through lower hot-pressing temperatures. By precisely controlling the addition ratio of pTSA (0-10%), the multifaceted impacts on the adhesive's curing behavior, bonding strength, water resistance, thermal stability, and microstructure were analyzed. The results demonstrate that pTSA substantially catalyzes the esterification crosslinking reaction between starch and citric acid. Differential scanning calorimetry (DSC) analysis reveals a significant reduction in the reaction peak temperature from 197.7 °C to 154.3 °C, which effectively lowers the hot-pressing temperature and provides more energy-efficient processing conditions for plywood production. When pTSA addition is within the range of 6-8%, the adhesive exhibits superior bonding performance and water resistance. Moreover, thermal stability is significantly enhanced and the microstructure becomes denser, collectively improving the overall performance of the plywood. This study not only provides a solid theoretical basis for the development of high-performance, environmentally friendly, starch-based wood adhesives but also offers strong technical support for the practical application of related technologies expected to promote the green and sustainable development of the wood adhesive industry.