Feasibly Developing\nPolyester-Type Poly(vinyl alcohol)\nAdhesive in One Go with High Water Resistance and Bonding Performance

Water-soluble poly(vinyl alcohol) (PVA) has great potential\nfor\nthe preparation of environmentally friendly adhesives. However, the\napplication of PVA adhesives in the wood industry has been limited\nby their poor water and mildew resistance. Herein, a polyester-type\nPVA adhesive (CPVA) with good bonding performance, water resistance,\nand antimildew performance was synthesized using PVA and citric acid\n(CA). The cross-linking reaction, including esterification between\nPVA and CA chains and etherification between PVA chains, was demonstrated\nby Fourier-transform infrared (FTIR) and X-ray photoelectron spectroscopy\n(XPS). Due to the cross-linked structure of the reaction, the CPVA1\n(mass ratio of CA/PVA = 1:1) adhesive showed a low soluble content\nof 5% when it was soaked in water for 24 h. The dry strength, warm\nwater (63 °C) strength, and hot water (93 °C) strength of\nthe plywood hot-pressed from the CPVA1 adhesive at 200 °C were\n1.06 1.52, and 1.45 MPa, respectively, which met the Chinese National\nStandard GB/T 9846-2015. The developed CPVA adhesive also adhered\nto glass and steel at room temperature. Therefore, the CPVA adhesive\ndeveloped in this study can serve as a potential candidate for the\nproduction of nonformaldehyde wood-based composites with excellent\nbonding strength, water resistance, and mildew resistance.