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Low-molecular-weight 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) was used to modify bamboo strips catalyzed by maleic anhydride. In this study, response surface methodology (RSM) was applied to optimize the treatment conditions for DMDHEU modification of bamboo. Three selected parameters, DMDHEU concentration, curing temperature, and curing time, were further optimized using response surface methodology via the box behnken design (BBD). The equilibrium moisture content (EMC), water absorption (WA), anti-swelling efficiency (ASE), mechanical properties, and mold resistances to (Aspergillus niger V. Tiegh, Penicillium citrinum Thom, Trichoderma viride Pers. ex Fr., and Botryodiplodia theobromae Pat.) were evaluated as the dependent variables. The results show that the dimensional stability and mold resistance of bamboo were enhanced remarkably, and the modulus of rupture (MOR) of bamboo was decreased after DMDHEU modification, while the modulus of elasticity (MOE) changed slightly, and the parallel-to-grain compressive strength (CS) was increased. Furthermore, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) were used to investigate the effect of modification on the bamboo microstructure and functional groups. In the context of SEM, TGA, and FTIR analyses, the thermal stability of bamboo modified with a medium or high concentration of DMDHEU was improved, the starch granules in the parenchyma cells of modified bamboo dissolved, and few resins were distributed in the lumens of treated bamboo. [ABSTRACT FROM AUTHOR]

This study evaluates the effect of 1% to 5% NaOH treatments of cotton stalk particles on the chemical composition and physical and mechanical properties of particleboards produced with this material. Gas chromatography and Fourier transform infrared (FTIR) spectroscopy indicated that the extractive, hemicellulose, and lignin content of the particles decreased during the alkali treatments, whereas the cellulose content increased. Thermogravimetric analysis (TGA) indicated that the untreated particles exhibited higher thermal stability than the particles treated with NaOH. The decrease in thermal stability of alkali-treated particles seems to be due to degradation of chemical components. Alkali treatments raised water absorption (WA) and thickness swelling (TS) of the produced particleboards. Except for 1% NaOH, the treatments reduced the modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond (IB) strength in relation to the board made with untreated particles. The 1% NaOH treatment of cotton stalks was more effective and beneficial, leading to particleboards with satisfying MOE, MOR, and IB values that met the requirements for general-purpose particleboards used in dry conditions, as indicated by the TS-EN 312 (2012) standard. [ABSTRACT FROM AUTHOR]