Utilization of enzymatic hydrolysate from corn stover as a precursor to synthesize an eco-friendly plywood adhesive

[Display omitted] •An eco-friendly plywood adhesive was synthesized by enzymatic hydrolysate from corn stover and ADP.•The synthesized adhesive exhibited excellent water resistance.•The synthesis and curing mechanism were investigated. In this study, concentrated enzymatic hydrolysate (EH) from corn stover and ammonium dihydrogen phosphate (ADP) were exploited as feedstocks to prepare a novel environment-friendly plywood adhesive. Firstly, the optimal synthesis conditions of the enzymatic hydrolysate-ammonium dihydrogen phosphate (EHADP) adhesive were investigated, and the results manifested that optimizing mass proportion between EH (solids) and ADP, synthesis temperature and time were 90/10, 100 °C and 1 h, respectively. When using EHADP synthesized under optimal synthesis conditions, the wet bond strength of the plywood met the requirements of China National Standard GB/T 9846-2015 (wet shear strength≥0.7 MPa). The chemical transformations during synthesis treatment on the uncured EHADP adhesive were analyzed by HPLC and 13C NMR, which showed that the EHADP adhesive was a complex mixture of ketones, monosaccharides, 5-HMF, furfural, deoxyfructosazine, Schiff bases, and amides. In addition, ATR FT-IR and Py-GC/MS were employed to analyze the curing mechanism of EHADP adhesive. The results showed that cured EHADP was formed mainly due to the polymerization of furan compounds, and the network was linked by imine linkages and dimethylene ether bridges. TG and DSC analysis showed that the mass degradation and endothermic reaction occurred at around 135℃, indicating the EHADP adhesive which prepared under the optimal synthesis conditions could cured at lower temperature.