Research Articles

Hardwood is currently underestimated with respect to its utilisation and its value creation potential. Due to changes in forest management in various countries, hardwood resources will become more important. However, solid hardwood (SH) production capacities, mainly structured as small to medium-sized enterprises (SME), are dropping or have dropped already because of changes in the wood products market. Enhancing the SH sector, the foundation of products, processes, and technology must be better understood. To support the SME SH business, the approach used here focuses on manufacturing processes of the first and secondary downstream industry. A multi-step Quality Function Deployment has been developed to match the manufacturing process with the product architecture, and a Process-Technology Matrix has been added to visualize the influence of technology on the manufacturing process. Both have been applied on three chosen hardwood products which are solid wood panel, parquet, and glued-laminated timber. The main contribution of the paper is a conceptual consideration with a conceptual framework rather than providing comprehensive solutions. Optimization potential exists within the SH manufacturing chain based on alternative the combinations of manufacturing processes and applied technologies.

Compared with conventional chemical deinking, enzymatic deinking is a more environmentally compatible alternative for processing recovered paper. In this study, a bacterial isolate identified as Achromobacter xylosoxidans (designated as L2) was found to be a promising candidate for a paper deinking process. It showed endoglucanase, β-glucosidase, endoxylanases, and filter paper degrading activities (FPase) with the maximal values of 2.60, 2.57, 3.08, and 24.58 U/mL, respectively. The optimal temperature and pH for FPase were determined to be 44 °C and pH 7.6. After two days of incubation with L2 at 130 rpm and 30 °C, the waste newspaper strips (0.5 cm × 5 cm) were disintegrated to debris with the average size of 3.5 mm (while that of the untreated without inoculation of L2 was 5.7 mm). The final brightness of the regenerated handsheets after incubation with L2 increased 3.7 units (31.4% ISO). The isolate and its complete lignocellulosic enzymes could be applied as deinking agents in the recycling of waste paper.

The exact mechanism behind the disintegration of chemical pulp fiber into cellulose nanofibers is poorly understood. In this study, samples were subjected to various homogenization cycles, indicating that the mechanism is a stepwise process. In the earlier stages of the mechanical process, a large amount of macrofibrils were created as the larger structures disappeared. Upon mechanical treatment these macrofibrils disappeared despite the increasing yield of cellulose nanofibers. The proposed model expands the understanding of the disintegration pathway and may provide additional insight as to how wood cells are converted into microfibrils.

The use of different mineral material types and contents in medium density fiberboard (MDF) production was investigated. Three different minerals (sepiolite, dolomite, and perlite) and five different ratios (3%, 6%, 9%, 12%, and 15%) were used according to the oven-dry wood fiber weight. These minerals were homogeneously added as powder between the wood fibers. Some physical, mechanical, limit oxygen index (LOI), and thermogravimetric analysis (TGA) tests of the boards were conducted. The mineral fillers negatively affected the physical properties such as water absorption (WA), thickness swelling (ThS), and mechanical properties such as modulus of rupture (MOR), modulus of elasticity (MOE), and internal bond (IB). However, LOI and TGA test results showed a positive effect on combustion resistance depending on the type and rate of mineral fillers.

Cement-based composites with lignocellulosic residues (e.g. wheat straw, rice husk, and bagasse) as fillers have reduced density and cost. Pretreatments have been applied in these raw materials to improve their compatibility with cement. This work aimed to characterize composites made from cement and wheat straw particles that had been chemically treated (2% NaOH solution) at two different temperatures (30 °C and 60 °C). Values of bulk density (209 kg·m-3) and specific density (679 kg·m-3) were determined for wheat straw at 12% moisture content. Straw yield was 71.9% and the particle size distribution showed large concentrations of wheat straw particulate material between 5- to 10-mesh. Composites made with wheat straw particles, in comparison to the control treatment, showed half the density, i.e., from 1800 to 900 kg·m-3. Also, the stress x strain curve presented a higher deformation before failure. NaOH pretreatment did not affect the mechanical properties of wheat straw composites.

The shorter natural durability and low energy density of eucalyptus wood hampers its use in generating energy. Torrefaction or pre-carbonization, which is treatment in low oxygen with temperatures between 200 °C and 300 °C, accumulates carbon and lignin, decreases the hygroscopicity, increases the energy efficiency, and reduces the attractiveness of wood to xylophagous organisms, such as termites. The objective of this study was to evaluate the resistance of fresh and torrefied Eucalyptus urophylla (20 min at temperatures of 180 °C, 220 °C, and 260 °C) to dry wood termites (Cryptotermes brevis), following IPT standards. The torrefaction process increased the resistance to dry wood termite attack after 45 d of exposure, with mass losses five times greater in the in natura wood compared with the wood torrefied at 260 °C. The larger visual damage to the in natura chips confirmed its lower resistance to dry wood termites. Torrefaction at 260 °C increased the resistance to dry wood termites and was more efficient with a lower mass loss and wear, and caused a greater mortality of dry wood termites.

Knowledge of the force required to overcome deformation at the proportionality limit, yield point, as well as knowledge of the effect of selected factors on the characteristics during bending stress, have scientific and practical significance. They are the basis for designing tools for bending and accurately determining the stresses to which products and their parts may be subjected during use. This study analyzed the effect of selected factors on the selected characteristics, including the forces at the proportionality limit (FE) and yield point (FP). The chosen factors of this study were the wood species (Fagus sylvatica L. and Populus tremula L.), non-wood component (carbon and fiberglass), non-wood component position in the composition matrix (up and down), material thickness (6 mm, 10 mm, and 18 mm), and adhesive used (polyvinyl acetate and polyurethane), as well as their combined interaction. The results contributed to the advancement of knowledge necessary for the study and development of new materials with specific properties for their intended use. The results could improve the innovative potential of wood processing companies and increase their performance and competitiveness in the market.

Microcellulose has shown advantageous character as a reinforcement in polymeric materials and produces relatively light compounds with high specific properties. This research aimed to obtain microcellulose (crystals and fibers) from the macrophyte Typha domingensis for use as a polypropylene reinforcement material for impact strength improvement and to use stearic acid as an interfacial modifier (surfactant) between the polypropylene and cellulosic materials. A commercial cellulose was used to compare the effectiveness of the microcellulose isolated from the macrophyte. The results demonstrated the procedures were efficient at obtaining microcellulose. The analysis of the chemical composition indicated an increase in the α-cellulose content from 63.2% in the raw material to 97.9% in the bleached cellulose. The X-ray diffraction patterns showed that the chemical treatments changed the crystallinity. The thermogravimetric analysis revealed an increase in the thermal stability of the bleached cellulose compared with that of the raw material. The thermal stability of the macrophyte was higher than that of commercial cellulose. The scanning electron micrographs revealed the presence of longitudinal slits that favored interactions with the polymer matrix. The impact strength was greatly improved for the composites compared with the pure polypropylene.

Noticeable improvements were achieved in the method for quality evaluation of formed paperboard containers. The method now allows for in situ evaluation of unavoidable wrinkle structures along the sealing rim of formed containers. An image of the sealing rim was provided. In this image, the contour of the sample was detected. The contour line was then offset to the inside of the sample, so that the new line was on the sealing rim, regardless of the original contour geometry. Along this offset contour line, the wrinkle structure was evaluated by using a previously described cross-correlation-based method. The repeatability and accuracy of the method were validated by comparing the detection results with the results from thorough human examiners. Furthermore, an approach to find the optimum settings for the wrinkle detection program is described and an outlook on implications for industrial adaptation of this method is given.

The use of charcoal and firewood for cooking is common in Zambia, and its utilization is such that the deforestation rate is high, energy utilization is low, and unfavorable cooking methods lead to high death rates due to indoor air pollution mainly from particulate matter and carbon monoxide. By using an alternative cooking method, such as pellet stoves, it is possible to offer a sustainable solution, provided that sustainable pellet production can be achieved. In this study, 12 different available biomaterials were pelletized in a single pellet unit to investigate their availability as raw materials for pellet production in Zambia. The study showed that sicklebush and pigeon pea generated the same pelleting properties correlated with compression and friction and that both materials showed low moisture uptake. The study also identified two groups of materials that broadened the raw material base and helped to achieve sustainable pellet production. Group 1 consisted of materials with equal pelleting abilities (miombo, peanut shell, pigeon pea, and sicklebush) and Group 2 consisted of materials that showed low impact of varying moisture content (eucalyptus, miombo, peanut shell, pigeon pea, and sicklebush). The hardest pellet was made from Tephrosia, which was followed by Gliricidia.