Analysis of the Cross-Linking Reaction of Lignin with Triethyl Phosphate by MALDI-TOF and 13C NMR

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

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.

Tannins: Prospectives and Actual Industrial Applications

The origin of tannins, their historical evolution, their different types, and their applications are described. Old and established applications are described, as well as the future applications which are being developed at present and that promise to have an industrial impact in the future. The chemistry of some of these applications is discussed where it is essential to understand the tannins and their derivates role. The essential points of each application, their drawbacks, and their chance of industrial application are briefly discussed. The article presents historical applications of tannins, such as leather, or traditional medicine, and more recent applications.

Chemical Composition and Thermal Behavior of Kraft Lignins

Lignin has great potential for utilization as a green raw material or as an additive in various industrial applications, such as energy, valuable chemicals, or cost-effective materials. In this study, we assessed a commercial form of lignin isolated using LignoBoost technology (LB lignin) as well as three other types of lignin (two samples of non-wood lignins and one hardwood kraft lignin) isolated from the waste liquors produced during the pulping process. Measurements were taken for elemental analysis, methoxyl and ash content, higher heating values, thermogravimetric analysis, and molecular weight determination. We found that the elemental composition of the isolated lignins affected their thermal stability, activation energies, and higher heating values. The lignin samples examined showed varying amounts of functional groups, inorganic component compositions, and molecular weight distributions. Mean activation energies ranged from 93 to 281 kJ/mol. Lignins with bimodal molecular weight distribution were thermally decomposed in two stages, whereas the LB lignin showing a unimodal molecular weight distribution was decomposed in a single thermal stage. Based on its thermal properties, the LB lignin may find direct applications in biocomposites where a higher thermal resistance is required.