Exploiting sugarcane waste molasses and dephenolized cottonseed protein as the promising component for eco-friendly wood-based panel adhesive formulation

Abstract

ABSTRACT In this study, sugarcane waste molasses (SWM) was utilized as a raw component to prepare an eco-friendly plywood adhesive. The optimization of preparation conditions, examination of thermal curing behavior, and exploration of the adhesive's curing mechanism were investigated. Based on the results, the optimal preparation conditions were determined as follows: the SWM is mixed with dephenolized cottonseed protein (DCP), a mass ratio of 2:1 between SWM and DCP, with a concentration of 75% and the addition of 7.5 wt% ammonium dihydrogen phosphate (ADP). Additionally, the optimal hot-pressing condition involved a temperature of 190°C for 10 min. Under these optimized conditions, the adhesive exhibited a maximum wet shear strength of 1.14 MPa, successfully meeting the China National Standard GB/T9846-2015. The curing behavior of the adhesive was investigated by analyzing thermal analysis and measuring the insoluble mass proportion. As the heating temperature and heating time increased, the insoluble mass proportion gradually rose. Thermogravimetric analysis (TG) showed that the thermal decomposition reaction temperature was 146.4°C and 202.05°C, differential scanning calorimetry (DSC) showed that endothermic reaction occurred at 135.8°C, exothermic reaction occurred at 227.8 °C. Through Fourier-transform infrared spectroscopy (FTIR) and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS), it was observed that the addition of ADP promotes the conversion of sucrose hydrolyzed products into furan compounds and reacts with proteins. Moreover, the amino and carboxyl groups of proteins react with the phenol hydroxyl groups of lignin to form C–N and C–O bonds, a polymer with a cross-linked network is formed.