Developing on the well performance and eco-friendly sucrose-based wood adhesive

The development of eco-friendly wood adhesives has attracted tremendous attention due to the aggravation of the oil resource crisis and the enhancement of environmental protection awareness. In this study, sucrose as a biomass material that was treated with an oxidizing agent to form bio-aldehydes, which were then reacted with hexanediamine via a Schiff base to prepare wood adhesives(OSUH). Several oxidants were tried in this work such as sodium permanganate(KMnO4), hydrogen peroxide(H2O2), sodium periodate(NaIO4), ammonium persulfate((NH4)2S2O8) and ammonium nitrate(NH4NO3). Among these, the (NH4)2S2O8, relatively low-cost, presented the best treatment effect. Hence, we further investigated the effects of the oxidation time of (NH4)2S2O8, the amount of (NH4)2S2O8 added and the pressing temperature on the bonding properties of the plywood bonded with this sucrose-based adhesive. The results show that the OSUH adhesive displayed the optimal bonding performance when the oxidation time, the addition of (NH4)2S2O8, and hot-pressing temperature were 45 min, 13 %, and 160 ℃, respectively. In this condition, the dry strength, 24 h cold water and 3 h hot water(63 ℃) soaking wet strength of the plywood are 1.52 MPa, 0.93 MPa, and 0.98 MPa, respectively, which indeed higher than the requirements of the GB/T 9846–2015 standard(≥0.7 MPa). The reaction mechanism between oxidized sucrose and hexanediamine was studied by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The experimental results showed that the CN chemical bonds were observed in the cured adhesives, which confirms that the reaction of oxidized sucrose with hexanediamine obtained a resin with three-dimensional network structure by means of a Schiff base reaction, thus ensuring favourable bonding performance.Therefore, this work provides a new approach to prepare a high-performance, water-resistant and eco-friendly sucrose wood adhesive that have the potential to be used in wood composites.