Research Articles

The use of chemithermomechanical (CTMP) pulp from rapeseed residues as raw material for the manufacturing of linerboard and fluting medium grades was investigated. For this purpose, different alternatives for improving mechanical and optical properties of rapeseed CTMP were studied, and the addition of nanofibrillated cellulose (NFC) was proposed to decrease the intensity of the beating process and enhance the final mechanical properties. Handsheets from each pulp were produced, and their properties compared to those of linerboard from recycled paper. Compared to kraft linerboard from recycled paper, rapeseed CTMP required less beating to reach an optimal breaking length. This reduction in beating can be combined with the addition of NFC to improve the mechanical properties of paper. Therefore, rapeseed CTMP from crop residues is a technically affordable alternative for the production of fluting and linerboard grades.

Utilization of oil palm trunk waste for production of environmental friendly binderless particleboard was studied. Response surface methodology was used to optimize the manufacturing conditions. The steaming temperature (100 to 120˚C), steaming time (25 to 50 min), hot pressing temperature (180 to 220˚C), and hot pressing time (15 to 30 min) were optimized in the ranges shown. The optimum conditions for making the particleboard were found to involve steaming for 46 min at a temperature of 120˚C before it was compressed using a pressure of 12 MPa, at a temperature 215 ˚C for 29 min. The internal bond (IB) strength, modulus of rupture (MOR), thickness swelling (TS), and water absorption (WA) were 0.54 MPa, 8.18 MPa, 22%, and 51%, respectively. The residual values of actual and model-based calculated IB, MOR, TS, and WA were found to be 0.1 MPa, 0.23 MPa, 2%, and 4%, respectively, which shows the significance of the study.

This study was conducted to evaluate suitability of luffa (Luffa cylindrica) fiber for medium density fiberboard (MDF) production. For the experiment, luffa and commercially manufactured fibers (Pinus sylvestris (30%), Fagus orientalis Lipsky (35%) and Quercus robur L. (35%)) with 11% moisture content were used. Luffa was mixed with commercially manufactured fibers in the following fashion: a layer of luffa fiber (30 g) placed in the middle of the mat, two equidistantly placed layers (60 g) in the mat, three layers (90 g) instead of two in the mat, and homogenously (90 g) dispersed without a district pattern in the mat, respectively. In panel production the only variable tested was the addition of luffa fiber at various weights to the wood fibers. Commercial urea formaldehyde (UF) adhesive was used as a binder. Chemical properties, including holo-, α-cellulose, and contents, alcohol-benzene solubility in dilute alkali (1% NaOH), and hot and cold water solubility, were determined. In addition, some physical and mechanical properties, such as density, thickness swelling (TS), bending strength (BS), modulus of elasticity (MOE), and internal bond (IB) of the panel of MDF were also measured. The chemical composition and solubility of luffa were found to be similar to those of nonwoods in general. Thus, the results suggest that luffa (Luffa cylindrica Mill.) fiber can be used as an alternative raw material for MDF manufacturing.

Combined treatment with steam and heat was imposed on green Turkey oak (Quercus cerris L.) wood, both for sapwood and heartwood. Steaming was carried out in an autoclave at 100, 120, or 130 °C, and then a portion of the samples was heated in an oven for 2 h at 120 or 180 °C. Extraction with ethanol provided the greatest extractive contents in sapwood, and the extractive quantity decreased as the heating temperature was increased to 180 °C. In contrast, extraction with dichloromethane provided the greatest extractive content in heartwood, and no sizeable differences were found among the various treatments. Lignin amounts increased with rising treatment temperatures combined with steaming at 100 and 120 °C until the greatest value of 31.1% lignin content was reached. However, the lignin content decreased as the steaming temperatures rose to 130 °C. In all the combined treatments, the lignin content was greater in heartwood than in sapwood. Moreover, both steaming and heating applied individually produced no significant effect on lignin content.

Impregnability of poles and other products made from spruce or fir wood decreases after the closing of toruses in the pits of tracheids, which usually occurs after their drying up to the fiber saturation point. With the aim of reopening access to the pits in the tracheids, the microscopic fungus Trichoderma viride was used for the enzymatic degradation of the pits in Norway spruce. During the summer, freshly cut and debarked spruce bolts were exposed in an inoculation mycelium of T. viride for 1, 3, 6, and 9 weeks under exterior conditions. Very good permeability and impregnability of spruce sapwood was observed after 1 or 3 weeks with no apparent change in its mechanical properties (Modulus of Rupture, Impact Bending Strength). On the other hand, previously closed pits of spruce heartwood remained unchanged in all experiments. Generally, coming out from achieved results and knowledge of other researches, bio-treatments of conifers are suitable for improving the impregnability of poles and other rounded timber products with the sapwood zone intact. However, bio-treatments for squared timbers with visible heartwood are usually a less appropriate.

The Eucalyptus genus plays an important role in the worldwide forest industry, with highly productive plantations supplying high-quality raw material for pulp and paper, wood, and biomass that would otherwise come from native forests. Lignin and extractives are important components for wood structure and protection but they are disruptive elements with respect to some industrial processes involving paper, pulp, and biomass production. This work evaluated effects of supplementation of flavonoids on the wood composition of Eucalyptus grandis x Eucalyptus urophylla (E. urograndis), a commercial hybrid. The wood samples were analyzed for extractives and lignin contents by wet chemical analysis, and the composition of lignin monomers and the carbohydrate hexosan/pentosan ratio were determined by analytical pyrolysis. The results showed that supplementation with the flavonoids naringenin and naringenin-chalcone led to an overall reduction of the extractive content and altered the monomeric composition of lignins towards a higher syringyl content. Thus, the treatment of Eucalyptus with flavonoids results in the improvement of wood quality for technological purposes.

Oil palm decanter cake (OPDC) is a potential lignocellulosic biomass for the biofuel industry. The fermentation conditions for biobutanol production using glucose from OPDC hydrolysate by Clostridium acetobutylicum ATCC 824 were optimized via response surface methodology (RSM). An analysis of variance (ANOVA) using 2–level factorial was successfully screened. Three significant variables were found to influence the biobutanol yield: glucose concentrations in the OPDC hydrolysate, inoculum sizes, and initial pH. The concentration of yeast extract, however, showed an insignificant effect in this study. The batch fermentation was analyzed using central composite design (CCD), and it yielded significant variables and the predicted optimum conditions were 70.00 g/L of OPDC hydrolysate, 16.20% of inoculum size, and an initial pH of 5.20. The predicted yield of biobutanol was 0.09 g/g using 70.00 g/L of glucose. The optimum conditions were validated, and the actual biobutanol yield was 0.11 g/g with 54.86 g/L of glucose consumption. The biobutanol production using synthetic glucose was 15.38% higher when compared to OPDC hydrolysate, but the utilization of OPDC as alternative substrate was still comparable with other findings.

Using medium-density fiberboard specimens, asymmetric four-point bending tests were conducted to obtain the Mode II critical stress intensity factor for this in-plane system. Because the medium-density fiberboard is in-plane quasi-isotropic about its board plane, the crack propagates obliquely with respect to the initial crack direction under the asymmetric four-point loading condition. A finite element analysis is required to obtain the Mode II stress intensity factor. The analysis herein was conducted to take into account the kink crack formation. In addition, a three-point bend end-notched flexure test was also conducted, and the results obtained by the experiments and numerical calculations were compared. When the initial crack’s length-to-specimen’s depth ratio ranged from 0.85 to 0.95 and when the additional crack length was taken into account, the Mode II critical stress intensity factor KIIc was appropriately obtained by the asymmetric four-point bending test.

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This study investigated the effects of heating on the morphology, pH, and buffering capacity of bast and core kenaf fibre. The bast material yielded longer and thinner fibres (with a higher aspect ratio) compared to the core. Changes in fibre morphology were clearly visible when the temperature of pulping was increased. The morphology of the bast fibre displayed significant variations following treatment at different pulping temperature (150, 160, 170, and 180 °C), time (1, 2, and 3 hours), and with the interaction between both parameters. Core fibre also exhibited significant variation in length, width, and wall thickness in all parameters, but lumen diameter and aspect ratio were not significantly affected by the same processing conditions. The pH value of both fibres was reduced as the temperature increased; core fibre was more acidic compared to bast fibre. Bast fibre exhibited greater acid buffering capacity and core fibre greater alkaline buffering capacity.