Synthesis and Characterization of Sucrose and Ammonium Dihydrogen Phosphate (SADP) Adhesive for Plywood

Abstract

The development of eco-friendly adhesives for wood composite products has been a major topic in the field of wood science and product engineering. Although the research on tannin-based and soybean protein-based adhesives has already reached, or at least nears, industrial implementation, we also face a variety of remaining challenges with regards to the push for sustainable adhesives. First, petroleum-derived substances remain a pre-requisite for utilization of said adhesive systems, and also the viscosity of these novel adhesives continues to limit its ability to serve as a drop-in substitute. Within this study, we focus upon the development of an eco-friendly plywood adhesive that does not require any addition of petroleum derived reagents, and the resultant liquid adhesive has both high solid contents as well as a manageably low viscosity at processing temperatures. Specifically, a system based on sucrose and ammonium dihydrogen phosphate (ADP) was synthesized into an adhesive with ~80% solid content and with viscosities ranging from 480–1270 mPa·s. The bonding performance of all adhesive-bound veneer specimens satisfied GB/T 9846-2015 standard at 170 °C hot pressing temperature. To better explain the system’s efficiency, in-depth chemical analysis was performed in an effort to understand the chemical makeup of the cured adhesives as well as the components over the time course of curing. Several new structures involving the fixation of nitrogen speak to a novel adhesive molecular network. This research provides a possibility of synthesizing an eco-friendly wood adhesive with a high solid content and a low viscosity by renewable materials, and this novel adhesive system has the potential to be widely utilized in the wood industry.

Investigation of Synthesis Mechanism, Optimal Hot-Pressing Conditions, and Curing Behavior of Sucrose and Ammonium Dihydrogen Phosphate Adhesive

“…The peak located at 214.4 ppm was attributed to a C=O bond of ketones [28], which formed during the dehydration of sucrose [29]. The chemical shifts located at 180.3, 164.0, 127.0, 111.0, 153.6, and 54.9 ppm were assigned to the C6, C5, C4, C3, C2, and C1 of 5-HMF [30][31][32], respectively, and this result has also been clarified by HPLC in previous research [26,27]. The peaks from 154.4 to 158.1 ppm and 140.87 to 143.8 ppm were attributed to C2-C5 of 2,6-deoxyfructosazine (2,6-DOF) and 2,5-deoxyfructosazine(2,5-DOF), respectively [33,34].…”

“…To investigate the synthesis mechanism of SADP adhesive, the 13 C NMR spectra ( Figure 1) were recorded to serve as an information source, and to supplement a previous discussion [26,27]. To clearly identify chemical shifts, the NMR spectra were divided to two regions: 220-106 ppm ( Figure 1a) and 106-50 ppm (Figure 1b).…”

“…To determine the effects of heating conditions on the chemical changes of the cured adhesive, FT-IR spectra of the insoluble mass were recorded (Figure 8). Since the effects of heating temperature on the chemical structure of cured SADP has been studied in our previous research [26], we only analyzed the influence of heating time in this study. Figure 8 shows the absorption bands of the insoluble mass heated at 170 • C for 5, 7, and 9 min.…”

“…Therefore, to explore the application of sucrose-ammonium dihydrogen phosphate (SADP) adhesives, we developed a material that can be synthesized with minimal water with a high solids content and suitable viscosities for introduction into existing plywood manufacturing operations. The optimal synthetic conditions and curing mechanism have also been clarified [26,27]. To further understand the mechanism and curing behavior, which was helpful to optimize this novel adhesive, on this study, a further research on the synthetic mechanism, optimal hot-pressing conditions, and curing behavior will be performed.…”

Preparation and Characterization of Waterborne UV Lacquer Product Modified by Zinc Oxide with Flower Shape

“…The super-hydrophobic modification of WUV can make it have the properties of self-cleaning [37,38], antifouling [38] and water resistance [39] and improve the erosion resistance [3, [40][41][42][43] of the coating, so that the wood material will possess a higher use value [44][45][46]. Yang et al [47] soaked the poplar wood in a compound solution of maleic rosin and ethanol for 24 h. After being taken out and dried, the sample was then soaked again in the solution of TiO 2 and modifier to obtain a super-hydrophobic wood with a contact angle up to 157 • .…”