Cross-linked peach gum polysaccharide adhesive by citric acid to produce a fully bio-based wood fiber composite with high strength

As a natural polysaccharide, efficiently converting peach gum (PG) into practical materials remains a significant challenge due to its complex structure and high molecular weight. This study developed a polysaccharide adhesive using PG as the primary raw material and citric acid (CA) as a cross-linking agent to produce a fully biobased wood fiber composite. The chemical compositions of PG and the synthesis process of PG-CA/55-45 adhesive were mainly discussed. The properties of the composites were explained through a microscopic perspective. The gel permeation chromatography (GPC) analysis revealed that the mean molecular weights of PG and PG-CA/55-45 adhesive were 9.07 x 106 Da and 9.98 x 104 Da, respectively. CA was introduced to depolymerize PG and cross-linked the degraded PG to form macromolecules with higher strength by the esterification reaction. PG-CA/55-45 adhesive demonstrated good mildew resistance and thermal stability. In addition, the composites exhibited excellent mechanical properties and water resistance. This study provided a simple and feasible approach to developing a polysaccharide adhesive for producing higher strength wood fiber composites, which can propose a new strategy for realizing the high-value utilization of PG.