Volume 9 Issue 1

Polyvinyl acetate (PVA) is commonly used to bond wood materials, but it generally exhibits poor performance when used in composites that require resistance to water and creep. However, it can be reinforced with different particles to improve its performance, making it useful for various applications. In this study, PVA was reinforced with cellulose fibers (CFs) at different loadings (1%, 2%, and 4%). A mixer was used to blend the PVA and CFs. Thermal properties and morphological structure of CF-reinforced PVA adhesive were studied by thermogravimetric analysis (TGA/DTG) and scanning electron microscopy (SEM). The lap joint shear strength of woods bonded by CF reinforced PVA adhesive was tested on poplar and Scots pine woods that had 12% moisture content. The addition of CFs to PVA increased the thermal stability of PVA to different extents depending on the degree of loading on the CFs. The results of morphological studies indicated that some fluctuations on the SEM pictures were observed due to the dispersion of the CFs in the PVA matrix. The results showed that lap joint shear strength of the two different species of wood increased in all states after CFs were added to the PVA.

To modify water absorption properties of bamboo fiber (BF) and high density polyethylene (HDPE) composites, heat treatment of BFs was performed prior to compounding them with HDPE to form the composites. The moisture sorption property of the composites was measured and their diffusion coefficients (Dm) were evaluated using a one-dimensional diffusion model. Moisture diffusion coefficient values of all composites were in the range of 0.115×10-8 to 1.267×10^-8 cm²/s. The values of Dm decreased with increasing BF heat-treatment temperature, and increased with increasing BF loading level. The Dm value of 40 wt% bamboo fiber/HDPE composites with BFs treated with 100 °C was the greatest (i.e., 1.267×10^-8 cm²/s). Morphology analysis showed increased fiber-matrix interfacial bonding damage due to fiber swelling and shrinking from water uptaking and drying. The mechanism of water absorption of the composite, indicated a general Fickian diffusion process.

Canola straw can be used as a raw material for the production of chemimechanical pulp (CMP). In this work, chemimechanical pulp was first produced from canola straw, and then the bleaching performance of the produced chemimechanical pulp was investigated under different conditions (dosages of NaOH and Na2SO3, time, and temperature). The results showed that the yield of chemical pretreatment in the CMP process varied between 57.6% and 64.9%, while the total yield of the process was between 54.1% and 61.9%. Subsequently, the CMP pulp produced via applying 4% NaOH and 8% Na2SO3 at 145 °C for 15 min was bleached with H2O2. The results showed that pulps bleached via applying one stage of 3% H2O2, 3% NaOH, 6% sodium silicate, 0.5% MgSO4, and 0.3% DTPA for 150 min possessed the highest brightness of 60.8% ISO, which is suitable for container board production.

Wood energy is derived from a variety of wood-based sources, the most prominent of which is the fuelwood obtained directly from trees and forests. The genus Acacia includes over 1,000 species spread all over the world. Six indigenous acacia species that grow naturally in the southwest region of Saudi Arabia were selected in November 2010 from the Abha and Al-Baha forests to determine the heating values and chemical constituents of their wood on a comparative basis. The results showed that they differed significantly in their chemical components and heating value. The highest heating value (20.45 MJ kg^-1) was found in the wood of A. tortilis, while A. ehrenbergiana had the lowest (18.00 MJ kg^-1)—although the latter species is the most popular in the Kingdom for firewood. Trees grown in the Al-Baha region had greater heating values than those in the Abha region. The heating values were highly positively correlated with the contents of lignin (R2=0.70) and total extractives (R2=0.56).

The aim of this study was to evaluate the performance of selective refining combined with ozone inter-stage treatment in a TMP process. A fractionation process was carried out to separate the primary pulp into two fractions, a long-fibre fraction and a short-fibre fraction. Different charges of ozone, namely 1%, 1.5%, and 2%, were used to treat the long-fibre fraction, and only the treated pulp went to the second refining stage. Finally, the secondary pulp was recombined with the primary short-fibre fraction to be compared to a control TMP trial. Results showed that 21% of the total refining energy can be saved when 1.5% ozone inter-stage treatment is applied before selective refining compared with whole pulp refining, when the pulp freeness is 100 mL. At this level of ozone charge, a slight increase in tensile strength is observed with no significant variation in tear index.

Ozonation was used for tertiary treatment of hardwood KP bleaching effluent. The objectives were to investigate the performance of ozonation on reduction of recalcitrant COD and color in the biologically treated effluent and to investigate the change in biodegradability of the effluent during the ozonation process. The results indicate that COD removal was enhanced by increasing solution pH and temperature, but that the recalcitrant COD was not completely removed from the effluent due to ozone-resistant substances that remain in the effluent after ozonation treatment. Ozonation of the effluent was more effective for decoloration than for COD removal. The highest decoloration efficiency and COD reduction were 99% and 55% at pH 11.7 and 25 °C. It was observed that the biological oxygen demand (BOD5) and BOD/COD ratio were 93 mg/L and 0.40, after 30 min of ozonation, which was an increase of up to 102% and 185%, indicating enhanced biodegradability of the effluent after ozonation treatment. This obvious increase in biodegradability implies that the ozone-resistant substances can be decomposed by ozonation to produce compounds that are more biodegradable.

Waste aspen sawdust was used as a precursor to prepare binderless active carbon monoliths (ACMs) with high porosities. The ACMs were prepared by activation with H3PO4 at different activation temperatures (500 to 700 °C) and retention times (1 to 3 h). Their morphologies, yields, textural properties, and microcrystalline structures were investigated using scanning electron microscopy (SEM), an analytical balance, N2 adsorption/desorption techniques, and X-ray diffraction (XRD). The results indicated that waste aspen sawdust could be successfully converted into highly porous binderless ACMs. The apparent specific surface area (SSA) and yield of ACMs were in the range of 688 to 951 m²/g and 26.6 to 36.2%, respectively. Highly microporous ACMs with a micropore percentage of 91.1%, apparent specific surface area of 951 m²/g, pore volume of 0.481 mL/g, and bulk density of 0.56 g/mL could be produced by activation at 700 °C for 1 h. Increasing the activation temperature or retention time increased the specific surface area, pore volume, and turbostratic degree, but decreased the yield.

In this work, a surface sizing agent for paper was prepared by the emulsion polymerization method, in which the collagen extracted from leather shavings was modified. The product was characterized using Fourier Transform-Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Energy Dispersive X-ray detector (EDX), and atomic absorption spectrophotometry. Corrugated papers were used as models. The synergy between modified collagen sizing emulsion and two commercial synthetic sizing agents was studied. Finally, the morphology of the papers before and after being treated was observed by Scanning Electron Microscopy (SEM). The results indicated that the sizing agent could be prepared using collagen as a raw material, which not only can alleviate a pollution problem in the leather industry, but also provide a novel alternative sizing agent for the paper industry, providing considerable economic, social, and environmental benefits to both industries.

The synthesis of a macro-initiator from cellulose in mixtures of zinc-based ionic liquid and polar solvents including deep eutectic solvent, dimethylformamide, acetone, and tetrahydrofuran (THF) was studied. The results of FTIR and NMR spectroscopies indicated that the cellulose-based macro-initiator can only be obtained in an inert ether solvent, THF. When the amounts of cellulose and zinc-based ionic liquid were fixed at 0.5 g and 18 mL, respectively, the degree of substitution of the cellulose-based macro-initiator obtained was increased from 11.0% to 17.4% as the reaction temperature was increased from room temperature to 40 °C, as calculated from TGA thermograms. When the amount of cellulose was cut in half, a degree of substitution of 27.5% was achieved due to lower viscosity and better homogeneity of the reaction medium. A green, new, and relatively cheap approach has been shown to be suitable for synthesizing a cellulose-based macro-initiator.

Understanding the structural features of lignin (L) and lignin-carbohydrate complexes (LCC) in bamboo (Phyllostachys pubescens Mazel) is important in order to expand the use of bamboo biomass. In this study, L and LCC were isolated from four-year-old mature bamboo using an organic solvent as an extractant. The structural features of L and LCC were characterized via UV-vis, FT-IR, NMR, sugar composition analysis, and alkaline nitrobenzene oxidation. L and LCC contained almost the same structural units: guaiacyl (G), syringyl (S), p-hydroxybenzoate substructures (PB),β–O-4’ substructures (A), 3-O-acetyl-(1→4)-linked- β-d-xylopyranosyl (βXyl3), (1→4)-linked-α(β)-d-xylopyranosyl (α(β)Xyl), and 4-O-methyl-α-d-glucuronic acid (MeGlcA(1→4)). The contents of the units varied between L and LCC. Carbohydrates linked with lignin in L and LCC mainly consisted of xylans. The sugar units of carbohydrates linked with lignin in LCC were determined to be of xylose (76.98%), arabinose (4.08%), glucose (6.47%), mannose (6.34%), altrose (3.69%), galactose (1.75%), and ribose (0.69%). The S (75.80%) and G (24.20%) units with a high S/G ratio of 3.13 were the main structural elements of lignin associated with carbohydrates in LCC.