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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.

Wood adhesives are mostly synthesized from unsustainable and hazardous petrochemical-based formaldehyde. Recently, an inorganic, sustainable and environmentally friendly aluminophosphate adhesive was developed for fabricating various wood-based panels. In order to increase its competitiveness, this study developed an approach for improving the interfacial adhesion of aluminophosphate. Hence, carboxymethyl cellulose was functionalized using 3-aminopropyl triethoxysilane to alter the chemical structures of the adhesive. Thereafter, a face-centered central composite design based on response surface methodology was employed to generate the optimum production conditions for the improved plywood interfaces. Adhesive concentration and hot-press temperature were seen as the significant factors within tested limits. The most appropriate production variables were suggested with a valid predictive model for such conditions. Also, the reaction mechanisms revealed the successful altering of the aluminophosphate properties with a well-uniform adhesive surface. The results indicate that modified adhesives are more thermally stable. Furthermore, the wet bonding strength of the modified adhesive was improved above the minimum threshold (Chinese type II standard ≥0.70 MPa). Therefore, the sustainable (i.e. continuous availability of CMC) approach adopted in this research could be considered as a viable method for improving the properties of aluminophosphate adhesives.

To reduce the use of formaldehyde wood adhesives, a chemical modification of starch with chitosan was explored to prepare an adhesive film for plywood with good adhesive properties, low price, non-toxic, and convenient sizing. The effect of chitosan content of the adhesive film on the shear strength of plywood was studied. The modification mechanism and bonding mechanism of the film were analyzed by FTIR, XPS, XRD and SEM. The results showed that when the amount of chitosan was 30% of starch dry weight, the dry-wet shear strength of plywood met the requirements of Chinese national class Ⅱ plywood (≧ 0.80 MPa). FTIR and XPS analysis showed that –NH2in the chitosan reacted with –COOH on starch and wood surface to form amide bond, which specifies the chitosan’s role as a coupling agent. XRD and SEM analysis showed that the addition of chitosan disturbed the otherwise orderly arrangement of a starch structure. The structure of the attained modified film is mostly amorphous. Sizing in the form of a adhesive film solves the disadvantage of difficulty in sizing starch adhesive. Compared with commercial adhesives on the market, this adhesive film has the advantages of low price, wide source of raw materials, non-toxic, and is expected to be a good substitute for formaldehyde adhesives on the market.

This study describes the application of aluminum sulfate Al2(SO4)3, boric acid H3BO3, phosphoric acid H3PO4 (Al&ndash, B&ndash, P) and amphiprotic surfactant material synthesis by the sol-gel process, which were adopted as novel precursors for wood modification. The efficacy of Al&ndash, P-treated wood was tested against Poria placenta and Coriolus versicolor. Untreated wood samples had higher mass losses (&gt, 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&ndash, 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&ndash, 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.