Search

The use of tri-formaldehyde adhesives (urea-formaldehyde resin adhesive, phenol-formaldehyde resin adhesive, and melamine resin adhesive) could endanger human health and damage the environment. Meanwhile, soy protein adhesive has received wide attention in wood-based panel preparation due to its green, sustainable, and abundant attributes. However, pure soy protein isolate (SPI) adhesives still lack competitive advantages compared to aldehyde adhesives. Herein, inspired by dietary pairing, a strategy was developed to obtain barley brewer's grain protein (BGP) from industrial waste for building the structural network of SPI adhesives. The globular protein of the SPI provides adhesion and hydrophilicity, and the BGP's alcohol-soluble protein and glutenin chain segments were beneficial for wet adhesion and water resistance. In addition, molecular restructuring, protein denaturation and chemical cross-linking were employed to prepare pure bio-based adhesives with desirable properties by denaturing SPI/BGP by adding papain (PA), sodium dodecyl sulfate or alkali modification and subsequently cross-linking with a bio-derived green cross-linker (TGA). Compared to the pure SPI adhesive, the in situ formulated SP/BGP-PA-T adhesive increased the wet strength, debonding work, wood breaking rate, and residual rate by 192.5% (1.55 MPa), 186.7% (0.453 J), 79%, and 83.4% (from 70.6%), respectively. Also, it decreased the viscosity and moisture absorption rate by 98.0% (5.07 Pa s) and 6.85% (from 11.84%), respectively. The modulated amino acid ratios, protein denaturation, molecular recombination and green chemical cross-linking provide a feasible strategy for developing desirable protein-based materials. [ABSTRACT FROM AUTHOR]

An aluminophosphate adhesive was used as the binder in plywood. The hot-pressing parameters of aluminophosphate adhesive-based plywood (APPs) including hot-press temperature (A), time (B), and pressure (C) were optimized using response surface methodology. Results indicated that the hot-press temperature was the most dominant factor. The maximum bonding strength of 1.98 MPa was found with an optimal parameter of 171 °C (hot-press temperature), 7.5 min (hot-press time), and 1.0 MPa (hot-press pressure). Additionally, the chemical reaction mechanism between aluminophosphate adhesive and wood fibers was characterized by X-ray photoelectron spectroscopy (XPS). Results showed that good interaction was generated between wood fibers and adhesives through their surface functional groups. In conclusion, the optimized pressing conditions of plywood significantly improved bonding strength of APPs. [ABSTRACT FROM AUTHOR]

In order to optimize its production technology, response surface methodology (RSM) was used to optimize the hot-pressing process during the preparation of chitosan-modified starch adhesive film. Ranges of hotpressing temperature, hot-pressing time, and adhesive consumption were selected based on single-factor tests. A quadratic regression model of the bonding strength was obtained by fitting the response value of the bonding strength of the plywood. The results showed that the adhesive consumption and the hot-pressing temperature had a significant effect on the bonding strength of the adhesive. Also, the interaction between the temperature, time, and adhesive consumption were significant. The optimum hot-pressing process parameters for chitosan-modified starch adhesive film were a hot-pressing temperature of 145.2 °C, a hot-pressing time of 182.7 s, and an adhesive consumption of 239.3 g/m². The predicted values of the quadratic regression model fit well with the actual values of the stability test. [ABSTRACT FROM AUTHOR]

This study describes the application of aluminum sulfate Al2(SO4)3, boric acid H3BO3, phosphoric acid H3PO4 (Al–B–P) and amphiprotic surfactant material synthesis by the sol-gel process, which were adopted as novel precursors for wood modification. The efficacy of Al–B–P-treated wood was tested against Poria placenta and Coriolus versicolor. Untreated wood samples had higher mass losses (>40%) compared to the treated sample, which had the lowest wood mass losses (of 4%) against P. placenta and C. versicolor. To analyze the reaction mechanism of Al–B–P wood, the mechanical properties, chemical structure, crystallinity, thermal analysis, binding energy and wettability was examined by modulus of rupture (MOR), modulus of elasticity (MOE), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Thermogravimetric analysis (TG) and X-ray photoelectron spectroscopy (XPS), respectively. Scanning electron microscopy- energy-dispersive X-ray spectroscopy (SEM-EDS) confirmed the wood colonization by fungi, and was used to identify the microstructures and morphologies changes that occurred in the cells during degradation by white and brown-rot fungi. At the same time, X-ray photoelectron spectroscopy (XPS) was employed to analyze the physical and chemical properties of the samples. Therefore, the study confirmed that Al–B–P and amphiprotic surfactant could replace the traditional wood preservative products, and have the potential to extend the service life of wood, particularly in soil contact and outdoor usage. [ABSTRACT FROM AUTHOR]