Research Articles

In this work, the physical and mechanical properties of bleached Eucalyptus pulp reinforced with nanofibrillated cellulose (NFC) are compared with those of traditional beaten pulp used in the making of writing/printing and offset printing papers. For this purpose, three different types of hardwood slurries were prepared: beaten pulps, unbeaten pulps reinforced with NFC, and slightly beaten pulps also reinforced with NFC. Physical and mechanical tests were performed on handsheets from these different slurries. The results showed that adding NFC to unbeaten pulps results in physical and mechanical properties similar to those in pulps used for printing/writing papers. Nevertheless, the best results were obtained in slurries previously beaten at slight conditions and subsequently reinforced with NFC. These results demonstrate that the addition of NFC allows a reduction in beating intensity without decreasing the desired mechanical properties for this specific purpose.

In this study, the optical and mechanical properties of polyurethane were improved by modified nanocrystalline cellulose (NCC). The surface of NCC was modified by 3-glycidoxypropyltrimethoxysilane (GPTMS) and 3-methacryloxy-propyltrimethoxysilane (MPS) to overcome the lack of compatibility with polyurethane. Polyurethane with modified NCC was characterized by wetting property, X-ray powder diffraction, and thermogravimetric analysis. The pencil hardness, specular gloss, and abrasion resistance of modified polyurethane were determined using the methods of Chinese National Standards GB/T 6739-2006, GB/T 9754-2007, and GB/T 1768-2006. The wetting property of NCC modified by GPTMS increased by 25.9%, and modification from MPS resulted in a 22.5% decrease of the contact angle. MPS-modified NCC affected the crystal structure and thermal stability of polyurethane more significantly than NCC modified by GPTMS. The pencil hardness of polyurethane was enhanced with 1.5% modified NCC. The specular gloss and abrasion resistance of modified polyurethane increased by 253.1% (1.0% NCC modified by GPTMS) and 59.4% (1.5% NCC modified by GPTMS), respectively. MPS-modified NCC led to the inconspicuous improvements.

In an effort to resolve problems related to the difficulty of degradation of the chelating agents EDTA and DTPA, this study used a kind of water treatment agent, 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP), as the chelating agent in the OPQP bleaching sequence of Acacia mangium kraft pulp. The Q stage was optimized with the use of response surface methodology (RSM) based on the Box-Behnken design (BBD). The results showed that the optimum chelating conditions for subsequent hydrogen peroxide bleaching were the following: Temperature of 54 °C, hold time 32 min, and dosage of agents 0.4%. These conditions resulted in the highest brightness value of 80.12% ISO and the selectivity coefficient of 0.46. Under these optimum chelating conditions, the results showed that the effect of HEDP in bleaching is better than that of EDTA with regard to viscosity of pulp, and that HEDP is similar to EDTA and DTPA in other properties.

Furfural residues produced from the furfural industry were investigated as a substrate for lactic acid production by simultaneous saccharification and fermentation (SSF). Alkaline peroxide was used for delignification of furfural residues to improve the final lactic acid concentration. The residue was treated with 1.3% to 1.7% hydrogen peroxide at 80 °C for 1 h with a substrate concentration of 3.33%. SSF of furfural residues with different delignification degrees were carried out to evaluate the effect of delignification degree on lactic acid production. Using corn hydrolysates/ furfural residues as substrates, SSF with different media were carried out to investigate the effect of lignin on the interaction between enzymes and lactic acid bacteria. Lactic acid bacteria had a negative effect on cellulase, thus resulting in the reduction of enzyme activity. Lignin and nutrients slowed down the decreasing trend of enzyme activity. A higher delignification resulted in a slower fermentation rate and lower yield due to degradation products of lignin and the effect of lignin on the interaction between enzymes and lactic acid bacteria. For the purpose of lactic acid production, a moderate delignification (furfural residues with the lignin content of 14.8%) was optimum.

This paper presents the development of particleboard based on common reed, reproducing the industry standard manufacturing process applied to wood chipboard. One of the main properties of the resulting board was its resistance to water, due to the hydrophobic properties of the common reed, despite there being no incorporation of melamine or any other waterproofing additive. The boards that were developed were analyzed using 2 mm and 4 mm sieves for fibre selection, a manufacturing pressure of 3 N/mm² and 25 N/mm², and a volume of urea formaldehyde resin content ranging from 5.2% to 13% (8 to 20% liquid format). Standard destructive tests were performed. It was found that under certain applied conditions, namely high pressure and adequate resin proportion (a pressure of over 3 N/mm² and over 15% liquid resin), Arundo donax L. particleboard demonstrated full recovery from the swelling test. This finding highlights an unmatched property in terms of recovery from the swelling test of the designed board. This property confers a interesting property to be used in high humidity environments without the need for special resin or waterproofing process.

The structural characteristics of corn stalks hemicelluloses during the active oxygen cooking process as a pretreatment of biomass conversion were investigated in this work. The hemicelluloses obtained from the corn stalks, pulp, and yellow liquor were evaluated by high-performance anion-exchange chromatography (HPAEC), Fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), and ¹H-¹³C 2D hetero-nuclear single quantum coherence (HSQC) spectroscopy. Based on the sugar and GPC analysis, FT-IR, and NMR spectroscopy, it could be concluded that the hemicelluloses were composed of backbones of (1→4)-β-D-xylopyranose substituted α-L-arabinofuranose and 4-O-methyl-α-D-glucuronic acid. During the cooking process, the hemicelluloses with more side chains were removed from raw material. The backbones were significantly damaged as well. Additionally, the ester linkages in the raw material were completely broken after the cooking.

An alkali-thermo-tolerant crude xylanase from Coprinellus disseminatus SW-1 NTCC1165 produced under solid-state fermentation conditions improves the brightness of sugarcane bagasse soda-AQ pulp by 7.3, 4.7, 6.1, and 8.2% in XODED, XOD(EOP)DP, OX(EOP)P, and XO(EOP)P bleaching sequences, respectively, at an enzyme dose of 8IU/g, a reaction time of 120 min, a consistency of 10%, and a pH of 6.4 at 55 °C. An improvement in brightness by 2.1% for pulp bleached by XO(EOP)P compared to OX(EOP)P sequence validates that xylanase treatment is more effective for hydrolysing lignin-carbohydrates complexes before oxygen treatment. AOX after XODED and XOD(EOP)DP sequences is reduced by 41.43 and 40%, respectively, compared to controls, but an increase in COD and color in studied bleaching sequences is attributable to the hydrolysis of hemicelluloses and the release of lignin-carbohydrates complexes after xylanase treatment. Xylanase treatment modifies fibre surface by introducing cracks, peelings, swelling, and external fibrillation, which facilitates faster penetration of bleach chemicals by disrupting physical barriers, as revealed by scanning electron microscopy.

Wood-plastic composites (WPC) have many applications as structural and non-structural material. As their outdoor application becomes more widespread, their resistance against weathering, particularly ultraviolet light and biodegradation becomes of more concern. In the present study, natural fiber composites (NFPC) made of bagasse and high density polyethylene, with and without pigments, were prepared by extrusion and subjected to accelerated weathering for 1440 h; then weathered and un-weathered samples were exposed to fungal and termite resistance tests. The chemical and surface qualities of samples were studied by ATR-FTIR spectroscopy, colorimetry, contact angle, and roughness tests before and after weathering. Using bagasse as filler does reduce the discoloration of weathered samples. Adding pigments may reduce the effect of weathering on lignin degradation, although it favors polymer oxidation, but it increases the weight loss caused by fungi. Despite the high resistance of samples against biological attack, weathering triggers attack by termites and fungi on the surface and causes surface quality loss.

Previous research has demonstrated that a laccase/xylanase system (LXS) from white-rot fungus (Lentinus lepideus) has the same ability to delignify as a laccase/mediator system (LMS). In order to enhance delignification ability of LXS treatment, the effect of refining on delignification with LXS treatment of Masson pine (Pinus massoniana) pulp was investigated by refining the pulp in a PFI mill to different revolutions (14,000/21,000/35,000/42,000/56,000) prior to LXS treatment (enzyme dosage 5/10/15IU/g o.d. pulp). The results indicated that both kappa number and yield of the LXS treated pulp decreased with increasing refining. A substantial delignification without severe yield loss could be achieved by moderate refining prior to LXS treatment. The SEM images suggested that refining increased the accessibility of the material to enzymes and thereby enhanced the delignification ability of LXS. The small cellulase activity detected in the LXS had little effect on the viscosity of the treated pulp even at high enzyme dosage.

The aim of this research was to study the physical and chemical performance of poplar wood treated by chemi-thermal modification. A thermal treatment was used to catalyze the effect of the methylolurea impregnated pre-treatment by curing the poplar wood at 160 ° C under atmospheric conditions. The results showed that the thermal treatment played an important role in the chemical and mechanical performance. Such an approach not only can significantly reduce the hygroscopicity, but also can increase the bending strength and compressive strength parallel to grain. The positions of the XRD peaks did not change, which indicated that the structure of cellulose was not noticeably affected by the thermal treatment. The FT-IR analysis showed that the intensity of hydroxyl and carbonyl absorption peaks decreased significantly, which indicated that the NH-CH2-OH of methylolurea reacted with the wood carboxyl (C=O) and hydroxyl (-OH). The TGA showed that the thermal stability of treated wood improved. The SEM showed that the cell wall and vessels were filled with impregnated chemicals.