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Biotechnology for Ecofriendly Processing
Series: De Gruyter STEM

Abstract

The implementation of circular economy in wood industries is an effective way for future sustainable development. The wood industries in China are not in the direction of circular economy approach due to less availability of assessment/calculation data of pollutants as per life cycle assessment (LCA) criteria. The present study focuses on the calculation of emission and pollutants from wood industries as per LCA; the emission and pollution data were collected from fiberboard Medium-density fiberboard (MDF), plywood and particleboard (PB) production. The comparative analysis of dust emissions, industrial waste gases and chemical oxygen demand (COD) were performed among three wood industries. The results revealed that the fiberboard industry was the highest emitter of dust, industrial waste gas and COD; and particleboard industry was the least emitter. Further, results indicated that pollutant index of wood industries were significantly changed between 2015 and 2017; the industrial waste water discharge increased five folds and the COD, dust and industrial gases increased two times. This study provides with the emission and pollutants data of wood industries as per LCA to promote the sustainable development for circular and low carbon economics.

Abstract

Wood decay is an economically significant process, as it is one of the major causes of wood deterioration in buildings. In this study, the decay process of Scots pine (Pinus sylvestris) samples caused by cellar fungus (Coniophora puteana) was followed by nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) methods. Altogether, 30 wood sample pieces were exposed to fungus for 10 weeks. Based on the decrease of the dry mass, the samples were categorized into three classes: decomposed (mass decrease 50–70%), slightly decomposed (10–50%), and nondecomposed (<10%). MRI made it possible to identify the active regions of fungus inside the wood samples based on the signal of free water brought by the fungus and arisen from the decomposition of wood carbohydrates. MRI implies that free water is not only created by the decay process, but fungal hyphae also transports a significant amount of water into the sample. Two-dimensional 1H T 1-T 2 relaxation correlation NMR measurements provided detailed information about the changes in the microstructure of wood due to fungal decomposition. Overall, this study paves the way for noninvasive NMR and MRI detection of fungal decay at early stages as well as the related structural changes.

Abstract

In this study, the effects of rubberwood extractives on the mechanical properties and fungal decay resistance of rubberwood-based wood plastic composites (WPCs) were explored. Three different solvents, benzene-ethanol, methanol, and deionized water, were used to remove the extractives of the rubberwood flour (RWF). The surface topographies of the prepared rubberwood-based WPC and the rubberwood itself were characterized using digital instruments and scanning electron microscopy (SEM). The results indicate that the mechanical properties of the WPC prepared using extracted RWF were higher than those of the WPC prepared with unextracted RWF. The sequences of resistance to the growth of mold on the surface of the WPC were ranked as follows: deionized-water-extracted WPC > methanol-extracted WPC > benzene-ethanol-extracted WPC > unextracted WPC. The WPC made with extracted RWF had better brown-rot resistance and worse white-rot resistance than the unextracted WPC. These results demonstrate that the removal of rubberwood extractives has a positive effect on the mechanical properties and mold and fungal decay resistance of rubberwood-based WPCs.

Abstract

Bamboo-based products are increasingly used in structural engineering fields. Specifically, their application requires consideration of factors that affect their service life, such as the fatigue behavior. Bamboo-based materials, such as bamboo scrimber, have a high density and uneven stress distribution. These structural properties seriously affect the quality of the bamboo-based materials, and lead to increased fatigue. To solve this problem, the fatigue behavior of bamboo laminated veneer lumber (BLVL) was studied. BLVL was manufactured by arranging rolled and broomed bamboo bundles and hot-pressing. This study describes the flexural fatigue behavior of BLVL at different stress levels. The fatigue was characterized by the fatigue failure, the fatigue hysteresis loops, the energy loss, and stiffness degradation. The results demonstrated that the BLVL material had good fatigue-resisting performances. The fatigue life of BLVL under 80% stress level was estimated to be about 1,700,000 cycles. The main failure modes of the BLVL included fiber tearing, fiber pullout, fiber breakage, and fiber-matrix debonding. The total energy loss at higher stress levels was less than that at low stress levels. Higher stress levels corresponded to a larger drop in stiffness.

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Abstract

The weakened microstructure of archaeological wood (AW) objects from waterlogged environments necessitates consolidation to avoid anisotropic shrinkage upon drying. Polymer impregnation through submergence or spraying treatments is commonly applied, and for larger and thicker objects, the impregnation period can stretch over decades. Thus, for efficient treatment, continuous monitoring of the impregnation status is required. Today, such monitoring is often destructive and expensive, requiring segments for extraction and chromatographic quantification. This study proposes an in situ Raman spectroscopic method for quantification of polyethylene glycol (PEG) in waterlogged AW. A calibration model was built on standards of PEG, cellulose powder, and milled wood lignin using orthogonal partial least squares (OPLS). The OPLS model had a strong linear relationship, and the PEG content in wood of varying degrees of degradation could be determined. However, the accuracy of the model was low with a root mean square error of prediction of 11 wt%. The low accuracy was traced to the heterogeneity in the calibration and validation set samples with regard to the small probing volume of the confocal instrumental setup.

Abstract

This study aimed to reduce the loss of mechanical strength in heat-treated rubberwood by rapid cooling. Heat-treated rubberwood specimens were prepared by controlling their cooling rate during the cooling phase of the heat treatment. The effects of cooling rate on the physical properties, chemical composition, and mechanical properties of heat-treated rubberwood were evaluated. Results indicated that cooling rate significantly influenced mass loss (ML). ML in heat-treated rubberwood cooled at 6 °C min−1 decreased by 23% relative to that in heat-treated rubberwood subjected to natural cooling. Compared with the heat-treated rubberwood subjected to natural cooling, the heat-treated rubberwood that was cooled at 4.5 °C min−1 increased in modulus of rupture (MOR), surface hardness, and screw withdrawal strength (tangential section) by 26, 8, and 16%, respectively. The cool rates exerted less effects on the dimensional stability, surface color, modulus of elasticity (MOE), compressive strength parallel to grain (CS), and screw withdrawal strength (radial section) of the heat-treated rubberwood. The application of rapid cooling to wood heat treatment could efficiently shortened the heat treatment period, thus increasing productivity.