Recently, the use of nanoparticles in Wood Plastic Composites (WPCs) has been considered by researchers. In this study, Multi-Walled Carbon Nanotubes (MWCNTs) were compounded with PVC, wood-flour, and foaming agent in an internal mixer. The wood flour amount was constant at 40 phr. For CNT and chemical foaming agent , different levels of 0, 1, 2 phr and 0, 3, 6 phr were considered respectively. The samples were foamed via batch process using a compression molding machine at 180°C. Morphology, density, water absorption, thickness swelling, and tensile properties of foamed composites were evaluated as a function of CNT and chemical foaming agent contents. The experimental results indicated that in the presence of CNT, cell density increased and cell size decreased. Density of the foamed composites was not affected by chemical foaming agent contents. Water absorption and thickness swelling of samples were decreased as compared with wood plastic composite without CNTs. Also, the maximum tensile strength and modulus were increased by up to 20% and 23% respectively.

Cellulose nanocrystals (CNC) and succinic anhydride-modified CNC from bleached soda bagasse pulp under different parameters were used to remove Cd+2 and Pb+2 heavy metal ions from aqueous solution. The aim was to modify the chemical structure of cellulose nanocrystal using succinic anhydride and to investigate the effect of CNC and succinic anhydride-modified CNC on the adsorption capacity of heavy metal ions. The adsorption parameters included pH (3, 5, 6, and 8), contact time (30, 60, and 90 min), and initial metal ion concentration (40, 120, 200, and 280 ppm). It was found at all pHs that the adsorption capacity of the succinic anhydride-modified CNC adsorbent was much higher than that of the default CNC adsorbent, and this difference was greater at higher pHs. The results showed that the maximum metal ion adsorption was obtained at pH 6 for Pb+2 and Cd+2 ions. Both types of CNC had a higher adsorption capacity for lead ions than cadmium ions. To investigate the kinetic models of adsorption, the pseudo-first-order and pseudo-second-order kinetics model were used. Adsorption on unmodified adsorbent gave a better fit to the Langmuir model than the Freundlich model for both Pb+2 and Cd+2 metals. In addition, the adsorption mechanism was changed by modifying the adsorbent, and then it had better fit to the Freundlich adsorption model. Adsorption of cadmium and lead metals by adsorbents fit better to the pseudo-first-order kinetics model.

Sugar cane bagasse was delignified in a two-step process with peracetic acid and alkali. Peracetic acid pre-treatment with concentration of 25% based on oven-dry fiber at 60 min, with a liquor to wood (L/W) ratio of 9:1 and a temperature of 50 °C improved the second stage delignification, compared with soda pulping. The second stage was carried out at three levels of temperatures, times, and 20% sodium hydroxide based on oven-dry fiber. Soda pulping at 165 °C, 120 min, 20% sodium hydroxide based on oven-dry fiber, and L/W 10:1 was selected to compare with two-step delignification. The two-step delignification reduces the severity of pulping conditions, including temperature and pressure, and subsequent imposes less risks compared with the soda pulping at 165 °C. The advantages of this method are high delignification and reduction of kappa number with respect to lower temperature and pressure compared with soda pulping. The total time in two-step was increased from soda pulping. Two optimum conditions for alkali step were obtained at 120 °C and 140 °C and 90 min for pretreated bagasse pulping, and similar properties were achieved with soda pulping at 165 °C and 120 min. The yield of fibers, Kappa number, and data analysis using Duncan method were measured and recorded.

The possibility of making glues of natural origin (pure lignin and lignin-gluoxal (instead of chemical resins for making plywood from poplar layer was investigated. For this purpose, lignin was reacted with glyoxal and the lignin-glyoxal glue was produced. To make the desired plywood, pure lignin (L.100%), lignin-glyoxal 15% (L.85%, G.15%), and lignin-glyoxal 30% (L.70%, G.30%) were used as the adhesive at three different levels. Ammonium chloride (1%) as the hardener and wheat flour (30%) as the filler based on the dry weight of the adhesive were also used. Plates made with urea formaldehyde resin at 160 g/m2 were considered as control samples. After the laboratory boards were produced, the physical and mechanical properties of samples, such as thickness swelling after 2 and 24 h of immersion in water, shear strength, modulus of rupture and modulus of elasticity, were measured. In addition, the groups and bonds in the pure lignin and lignin-gloxal adhesives were identified by Fourier transform infrared (FTIR) spectroscopy. In most tests and compared to the boards made of the adhesives and control boards, the lignin-glyoxal 30% (L.70%, G.30%) glue came closest to the performance of the control glue.

ThermoWood is a wood modification method that is used to improve the wood application and dimensional stability of wood. In this study, poplar wood (Populus nigra) was used in two age groups of 18- and 38-year-old trees to investigate the effect of tree age, thickness, and depth of heat-treated timbers on mechanical properties and density. In each age group, the timbers were prepared according to thickness of 40, 50, and 60 mm. The experimental samples were prepared from the surface (S) and middle (M) depth of heat-treated timbers based on age and thickness. Some properties of heat-treated and control wood such as density (oven-dry density, air-dry density, and basic density) and mechanical properties (modulus of rupture (MOR), modulus of elasticity (MOE), and impact strength) were measured. In general, density and mechanical properties of heat-treated wood were decreased compared with the control samples. Density and mechanical properties of heat-treated and control wood samples were increased from 18- to 38-year-old trees. There were no differences in density and mechanical properties after changing thickness. Surface and middle depth specimens of heat-treated timbers showed a positive effect on the impact strength but had no considerable effect on densities and other strengths of heat-treated wood timbers.

The effect of changing the sequence of refining and enzymatic treatment on the properties of deinked pulp from mixed office waste paper (MOW) was investigated. The sequences included refining before and after enzymatic treatment. Refining was applied for 700 and 1500 revolutions, and the consistency of pulps during enzymatic treatment was 5, 8, and 13%. Enzymatic treatment was applied for 20, 40, and 60 min. After each of the sequences, the deinking stage was the same. When refining was applied after the enzymatic treatment, the freeness of pulp was greater than that of the pulp on which refining was conducted before the enzymatic treatment, at a constant refining speed. Better strength properties were produced when refining was carried out before the enzymatic treatment. Also, the results of testing the optical properties of deinked pulp showed that brightness and ERIC improved when refining was carried out before the enzymatic treatment.