Wood Content Research Articles

Nondestructive prediction of fire performance in fire retardant-treated wood using x-ray computed tomography

The fire performance of fire retardant-treated wood can be evaluated based on how much of the chemical retardant is used. Therefore, methods for identifying chemical content in wood are needed. Stereo images of wood samples before and after the fire retardant treatment were captured using micro-focus X-ray computed tomography. Image brightness values, indicating concentration, were calculated using binarized images sliced from the X-ray images. Changes in integrated brightness values before and after treatment showed a strong positive correlation with chemical content at a 1% significance level. The chemical content of the retardant-treated wood was predicted based on the relationship between the two. The predicted values were in agreement with the values measured using the leaching method. Fire performance tests of the fire retardant-treated wood were conducted using a cone calorimeter. The treated wood was classified as fire-retardant and non-combustible wood. In addition, the fire performance predicted by the relationship between changes in integrated brightness values and chemical content agreed with the classification by the fire performance test. These findings suggest that X-ray computed tomography can be potentially used to predict the chemical content of fire retardant-treated wood.

Secondary metabolites and nutrients explain fungal community composition in aspen wood

Fungi are the main decomposers of litter and wood, driving carbon and nutrient cycles. Despite a large number of studies, fungal community composition is remarkably difficult to predict. In the present study, we explore the importance of secondary metabolites and nutrient content in wood and bark as determinants of fungal community composition. We used aspen ( Populus tremula ) logs of similar size, from one location, and measured concentrations of carbon, nitrogen and secondary metabolites in bark and wood sampled shortly after felling. Fungal DNA was extracted from logs directly after felling and after two seasons of decomposition, and the fungal communities were assessed using DNA-metabarcoding. Concentrations of metabolites varied considerably between individual trees, and we also observed significant differences within single trees. Plant metabolites and nitrogen concentrations significantly affected fungal community composition. For the overall fungal communities and for wood saprotrophic fungi, the explanatory power of wood and bark metabolites was highest in logs decomposed over two seasons. In recently felled trees however, concentration of metabolites had a stronger effect on plant pathogens and endophytes. We conclude that secondary metabolites represent an overlooked, but important niche dimension for fungal communities in both functional sapwood and dead wood.

Processing‐Properties Correlation for a Rubber Toughened Wood Plastic Composite

AbstractIssues of environmental sustainability attract more and more attention to polymeric systems that can be considered environmentally friendly. A class of materials that meets the demand for a lower environmental impact are Wood Polymer Composites, or WPCs. These are thermoplastic polymers compounded with wood fibers or flour, usually coming from industrial or agricultural waste. With these materials, the greatest benefit is obtained by increasing the wood content, thus reducing the percentage of polymeric matrix. On the other hand, two of the main drawbacks coming from an increase in the wood content are brittleness and a significant reduction in processability. In this work, concentration will be on reducing brittleness by adding different amounts of a toughening agent (i.e., a thermoplastic elastomer) and on finding the optimal combination between processing conditions and elastomer content. This target will be obtained by comparing the tensile properties of all composites that are produced with different extrusion conditions with their apparent density.

Rapid lignin quantification for fungal wood pretreatment by ATR-FTIR spectroscopy

Lignin determination in lignocellulose with the conventional two-step acid hydrolysis method is highly laborious and time-consuming. However, its quantification is crucial to monitor fungal pretreatment of wood, as the increase of acid-insoluble lignin (AIL) degradation linearly correlates with the achievable enzymatic saccharification yield. Therefore, in this study, a new attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy method was developed to track fungal delignification in an easy and rapid manner.Partial least square regression (PLSR) with cross-validation (CV) was applied to correlate the ATR-FTIR spectra with the AIL content (19.9 %–27.1 %). After variable selection and normalization, a PLSR model with a high coefficient of determination (RCV2 = 0.87) and a low root mean square (RMSECV = 0.60 %) were obtained despite the heterogeneous nature of the fungal solid-state fermentation. These results show that ATR-FTIR can reliably predict the AIL content in fungus-treated wood while being a high-throughput method. This novel method can facilitate the transition to the wood-based economy.

Comparative studies of the macro- and microstructures of stump-root wood and stemwood

Abstract It is found that the existing problem of wood resources can be partially solved by attracting additional reserves, in particular, stump-root wood (SRW). In order to apply SRW in woodworking and to fill the scientific base with indicators of the macro- and microstructures of the stump-root systems of individual species, studies were carried out on the main characteristics that are decisive for using composite materials in the industrial production. Based on the study results, it was found that there are differences in the internal structure between SRW and stemwood (SW). It was found that in all species, the width of annual rings in the SRW was greater than that in the SW, in particular, in pine (Pinus sylvestris L.) – by 84.62%; in spruce (Picea abies Karst.) – by 73.68%; in fir (Abies alba) – by 93.75%; in aspen (Populus tremula L.) – by 35.71% and in birch (Betula pendula Roth.) – by 105.00%. It has been found that the content of late wood in the SRW of coniferous tree species is less than that in the SW, on average by 20–25%, and the number of annual rings per 1 cm in the SRW is 40–52% less than in the SW. Differences in the microscopic structure between SRW and SW are revealed, which consist in the difference in the size of tracheids in softwoods and of vessels and fibres of libriform in hardwoods. It was found that the transverse dimensions of early tracheids in the SRW were larger than in the SW, in particular, in the radial direction by 19–33% and in the tangential direction by no more than 15%, and the interval of dimensions in the radial direction was 1.5–2.5. It was found that the early tracheids of root wood had thinner walls (by 19–28%) and a larger internal cavity (by 15–25%) compared to similar elements of SW. It was revealed that the diameters of vessels and fibres of libriform in SRW are greater than in SW, in particular, in aspen (Populus tremula L.) – by 20.41% for vessels and by 12.95% for libriform fibres and in birch (Betula pendula Roth.) – by 20.69% for vessels and by 18.41% for libriform fibres. The practical significance of the studies lies in the fact that the obtained characteristics of the structural components of the SRW can be used to predict the strength indicators of composite materials.

Thermal and mechanical properties of a high-density polyethylene (HDPE) composite reinforced with wood flour

To keep up with the rate of growth and global demand, it is necessary to manufacture products with high performance and improved durability. Wood-plastic composites (WPCs) are a rapidly growing class of construction materials formed by mixing wood fibers with a polymer matrix at a high temperature. However, significant technical issues remain, such as low thermal resistance, low water resistance, and limited interfacial contact or compatibility between wood fiber and the polymer matrix, which results in poor adhesion of the wood particles, etc. The structure and properties of the matrix/fiber interface can indeed have an impact on the final properties of the composites. To this end, good interfacial adhesion improves stress transmission from the matrix to the fiber, as well as composite performance. Therefore, chemical modification has been the most effective way to chemically bond the matrix to the filler. In this study, the modification is achieved by using maleic anhydride as a coupling agent which promotes the formation of chemical or material bonds between the wood flour (WF) and the polymer matrix. Three WF/high-density polyethylene (HDPE) composite blends with WF contents of 40%, 50%, and 60% were evaluated for density, flexural properties, hardness test, and thermal analysis. Physical tests showed that increasing the wood content of the composite from 40% to 60% increases the density and hardness of the WPC from 1,047 g/cm3 to 1,097 g/cm3 and from 64.5 to 67.7 respectively. On the other hand, increasing the wood flour content to 60% decreases the flexural strength from 37.524 MPa to 27.512 MPa, while the flexural modulus increases from 2176.125 MPa to 3568.284 MPa. In general, the results indicate that the developed WF/HDPE has suitable mechanical and thermal properties for outdoor applications.

Aspartic proteases modulate programmed cell death and secondary cell wall synthesis during wood formation in poplar.

Programmed cell death (PCD) is essential for wood development in trees. However, the determination of crucial factors involved in xylem PCD of wood development is still lacking. Here, two Populus trichocarpa typical aspartic protease (AP) genes, AP17 and AP45, modulate xylem maturation, especially fibre PCD, during wood formation. AP17 and AP45 were dominantly expressed in the fibres of secondary xylem, as suggested by GUS expression in APpro::GUS transgenic plants. Cas9/gRNA-induced AP17 or AP45 mutants delayed secondary xylem fibre PCD, and ap17ap45 double mutants showed more serious defects. Conversely, AP17 overexpression caused premature PCD in secondary xylem fibres, indicating a positive modulation in wood fibre PCD. Loss of AP17 and AP45 did not alter wood fibre wall thickness, whereas the ap17ap45 mutants showed a low lignin content in wood. However, AP17 overexpression led to a significant decrease in wood fibre wall thickness and lignin content, revealing the involvement in secondary cell wall synthesis during wood formation. In addition, the ap17ap45 mutant and AP17 overexpression plants resulted in a significant increase in saccharification yield in wood. Overall, AP17 and AP45 are crucial modulators in xylem maturation during wood development, providing potential candidate genes for engineering lignocellulosic wood for biofuel utilization.

Physical, Mechanical, and Durability Properties of Concrete Containing Wood Chips and Sawdust: An Experimental Approach

With a circular economy in the spotlight, wood waste has emerged as an important secondary raw material. Bearing this in mind, a comprehensive experimental study was carried out to evaluate the feasibility of using concrete compositions containing wood chips and sawdust for structural and non-structural building applications. First, the mineral and wood aggregates used in the composite design were fully characterized. Twelve compositions containing varying types of wood particles in different amounts were then produced and characterized in terms of physical and mechanical performance (e.g., mass density, compressive strength, modulus of elasticity, and flexural strength). Subsequently, two compositions with optimized features (mass density below 2125 kg/m3, compressive strength above 25 MPa, and maximum volume content of wood) were selected to undergo additional experimental tests. These included microstructural characterization, as well as the evaluation of relevant durability (e.g., wetting–drying, freeze–thaw, and thermal shock cycles) and hygrothermal (e.g., thermal conductivity, water absorption, and shrinkage and expansion) properties. All compositions showed compressive strength above 30 MPa. The durability assessment of selected compositions further showed that compressive strength after relevant artificial aging was still higher than the predefined criteria. Promising hygrothermal properties (minimal water absorption and low thermal conductivity) were also recorded.

THE CHANGES IN THE SURFACE OF FLAT PRESSED WOOD-PLASTIC COMPOSITES EXPOSED TO ARTIFICIAL WEATHERING

In this study, the wood flour content's effect on the weathering performance of flat pressed WPC was investigated. The high density polyethylene was reinforced with four different wood flour content (10%, 30%, 50%, 70%). The weathering performance of WPC was determinedby the 400 h of artificial weathering test. According to the results, the color change is inevitable aslong as the wood flour is used as filler. Surprisingly, the highest color change was obtained from WPC containing 30% WF, contrary to 70% of wood flour. Similarly, the whiteness of thesurface of WPC increased with exposure time. The photooxidation resulted in the chain scission and shorter molecules, which were observed by ATR-FTIR analysis. The changes in the intensity of characteristic polymer (2914 cm-1and 2846 cm-1) and wood peaks (1510 cm-1and 1027 cm-1) exhibited the photodegradation on WPCs' surface, which resulted in color change. Moreover, the light microscopy investigation showed surface degradation. Theextensive weathering conditions causedsurface cracks and surface roughness. The visual appearance of WPCs also demonstrated how to change the surface character of WPC during the400 h of artificial weathering. In conclusion, the increase inthe wood content increased theintensity of degradation.

Study on the Direct Transformation of Milk Bottle and Wood into Wood–Plastic Composite through Injection Molding

Plastic has transformed the world; however, it generates a huge amount of waste plastics. It is well evident that, if urgent action is not undertaken on plastic pollution, it will pose threats to not only the environment, but also human life. Just simply discarding waste plastics will result in wasting a lot of valuable materials that could be recycled. Recently, the use of waste plastics has been considered for producing wood plastic composites (WPCs), which are superior to normal wood. Waste plastics are pelletized using an extruder and are then subjected to injection molding. In this study, investigations were carried out to determine the possibility of producing WPCs without the palletization of waste plastic to turn WPC production into a shorter, simple, and easy-to-achieve process. Here, a waste milk bottle, a familiar single-use plastic, was picked as a case study. Waste plastic granules and wood particles were mixed and directly injection molded to produce valuable WPCs. The water absorption of WPCs with 20% wood is 0.35%, and this increased to 0.37% when wood content was increased to 40%. The tensile strength at yield, elongation at break, and impact strength of WPCs with 20% wood content are 19.54 MPa, 5.21%, and 33.92 KJ/m2, respectively, whereas it was 17.23 MPa, 4.05%, and 26.61 KJ/m2 for the WPCs with 40% wood content. This process can be a potential solution for two problematic wastes at the same time.

Transfer of a calibration model for the prediction of lignin in pulpwood among four portable near infrared spectrometers

In order to reduce the time and cost for near infrared (NIR) model development and maintenance, the transfer of NIR spectra measured on four different portable spectrometers (one master and three target instruments) for predicting the lignin content of pulp wood is investigated in this work. Eighty-two wood samples were prepared by chipping and grinding, and their NIR spectra were recorded with four spectrometers. Calibration models for the determination of lignin in pulp wood have been developed by partial least squares (PLS) regression, while average Mahalanobis distances (AMD) and average differences of spectra (ADS) were used to quantify the spectral differences. Then piecewise direct standardization (PDS) has been applied, and compared to direct standardization (DS), slope/bias correction (SBC) and canonical correlation analysis (CCA). The accuracy of the models has been evaluated by comparing their prediction performance. The results indicated that the prediction performances of the three target instruments are greatly improved by using the three algorithms. The advantage of the PDS algorithm is that fewer samples are required for the transfer sets, which means lower model maintenance cost for practical applications. When it comes to window size setting procedure, it was found that if there are large spectral differences between the master and the target spectrometer, a large window size should be used and if the spectral difference is a significant lateral shift, an asymmetric window with appropriate window size is necessary to ensure a good transfer performance for the PDS algorithm.

Prediction of the extractives content of Eucalyptus globulus wood using NIR-based PLS-R models. Influence of spectral range and preprocessing on the percentage of outliers detected

Eucalyptus globulus is an important pulpwood source due to favorable wood characteristics, including low extractive content. However, there is significant tree-to-tree variation that can be exploited in breeding. This requires screening a large number of samples, which NIR and PLS-R make possible. Models are typically developed for a specific set of samples prepared in the same way. The question is: how well these models predict samples that are different from the ones used in the model. Models developed to determine the extractive content of Eucalyptus globulus wood from Australia were used to E. globulus wood from Argentina, which differed in age and sample preparation. The main difference between spectra of the two origins was in the OH combination band, despite the fact that samples were dried identically. Due to this difference, models that included the O-H band assigned above 73% of the spectra as outliers regardless of preprocessing, whereas models that did not include the O-H band assigned fewer spectra as outliers. The differences in the OH band were attributed primarily to differences in particle size and extractive content, rather than to differences in humidity content. However, all models predict similar results for all samples, including outliers.

The Larix kaempferi genome reveals new insights into wood properties.

Here, through single-molecule real-time sequencing, we present a high-quality genome sequence of the Japanese larch (Larix kaempferi), a conifer species with great value for wood production and ecological afforestation. The assembled genome is 10.97 Gb in size, harboring 45,828 protein-coding genes. Of the genome, 66.8% consists of repeat sequences, of which long terminal repeat retrotransposonsare dominant and make up 69.86%. We find that tandem duplications have been responsible for the expansion of genes involved in transcriptional regulation and stress responses, unveiling their crucial roles in adaptive evolution. Population transcriptome analysis reveals that lignin content in L. kaempferi is mainly determined by the process of monolignol polymerization. The expression values of six genes (LkCOMT7, LkCOMT8, LkLAC23, LkLAC102, LkPRX148, and LkPRX166) have significantly positive correlations with lignin content. These results indicated that the increased expression of these six genes might be responsible for the high lignin content of the larches' wood. Overall, this study provides new genome resources for investigating the evolution and biological function of conifer trees, and also offers new insights into wood properties of larches.

Prediction of wood moisture content based on THz time-domain spectroscopy

A new method for predicting wood moisture content using terahertz (THz) time-domain spectroscopy (TDS) is presented in this paper. The THz wave is a promising method in measuring wood moisture content due to its sensitivity to water, impressive penetration ability in wood, and no destructive effect on wood interior. In this study, the selected wood, Douglas fir (Pseudotsuga menziesii), with different moisture content was studied. THz-TDS was used to extract the optical parameter of the sample. The THz refractive index and absorption coefficient spectrum of the wood were calculated. The first and second derivatives of the absorption coefficient spectrum were processed to obtain the first and second derivative spectra. The successive projections algorithm (SPA) was used to select the characteristic frequency for the THz absorption coefficient spectrum and its first and second derivative spectrum of the wood. A regression prediction model of wood moisture content was established by partial least squares regression (PLS). The results showed that the proposed model based on the second derivative spectrum had the best prediction effect for the moisture content of wood.

Dimensional stability and mechanical properties of extruded-compression biopolymer composites made from selected Nigerian grown wood species at varying proportions

250 µm particle size of wood and polyethylene (PE) materials were compounded at mixing proportions of 60/40, 70/30, and 80/20 (with an increase in polymer to decrease in wood content) and extruded using a single screw extruder at a temperature range of 110–135 °C. The particles of Gmelina Arborea, Tectona grandis, Cordiamilleni, and Nauclea diderichii with recycled Polyethylene were compounded and compressed at 175 N/mm to produce biopolymer composites. The biopolymer composites were subjected to dimensional stability test at 24 h of the water soak method and the ability to withstand load-bearing capacity was investigated. The outcome of the results shows that extruded-compressive biopolymer composites had values ranging from 0.06–1.43 g/cm3, 0.38–3.41%, and 0.82–6.85% for observed density, water absorption, and thickness swelling at 24 h of a water soak test. The mechanical properties values ranged from 0.28 Nmm−2–21.35 Nmm−2 and 0.44–550.06 Nmm−2 for flexural modulus and strength; and 191.43 Nmm−2–1857.24 Nmm−2 and 0.35 Nmm−2–243.75 Nmm−2 for tensile modulus and strength respectively. It was observed that moisture uptake and strength displayed by the composites vary accordingly in values obtained for wood species at different mixing proportions. As observed that the more polyethylene content is compounded to wood, the better its dimensional stability, and flexural and tensile properties. The wood particles of Cordiamilleni compounded at a proportion of 60 to 40 (polyethylene/wood) performed best in dimensional stability and load-bearing capacity. This study confirmed the effect of methods on wood species and recycled PE for manufacturing wood polymer-based composite for both indoor and outdoor applications.

Comparison of PM10 emission from co-combustion of Platanus orientalis leaf and wood in different seasons with coal

Platanus orientalis is widely planted in southern Eurasia, accounts for almost 30% of the avenue trees in China. This work aims to research the effects of seasonal change on mineral elements in the green leaf (GL), yellow leaf (YL) and wood (Wood) of P. orientalis, including their effects on PM10 emissions during co-combustion with coal. Fuels were combusted in a drop tube furnace at 1500 °C to collect PM10. Results show that seasonal change does affect the element contents in leaf. Higher elemental contents, including K, Na, Cl, S and P, are found in GL than those in YL; YL contains more HCl-soluble and less water-soluble Ca. The elemental content in Wood is significantly lower than that in leaf. In terms of PM10, the particle size distributions from pure combustion of three biomass follow a bimodal distribution; GL combustion generates more particulate pollutants than YL does, both PM1 and PM1–10; the combustion of Wood produces the least PM10. The most notable interaction occurs in the case of SF-GL during co-combustion, where the yield of PM10 is only approximately 40% of the calculated value. Overall, the co-combustion of P. orientalis biomass and coal effectively reduced the generation of PM10.

What Elevation Makes 2.5D Prints Perceptually Natural?

Elevation plays a considerable role in naturalness perception of 2.5D prints. The necessary level of elevation to make 2.5D prints look perceptually natural may vary from application to application. Therefore, one needs to know the right elevation for specific applications to make the prints look perceptually natural. In this work, we investigated what elevation makes 2.5D prints of wood images perceptually natural. We worked with various wood content images such as wooden wicker, wall, roof, and floor. We found that the optimal elevation that makes 2.5D prints of wood images perceptually natural is content-dependent and in a range between 0.3 mm and 0.5 mm. Moreover, we found that the optimal elevation becomes 0.5 mm if we consider images of wood regardless of the wood content. In addition, there was a high correlation between majority of observers on naturalness perception of 2.5D prints of wood images.

Influences of cement brands and mixing ratios on the physico-mechanical properties of cement bonded particleboards made of wood particles of Gmelina arborea, Afzelia africana and Triplochiton scleroxylon

Cement bonded particleboards (CBPs) were produced of wood particles of Gmelina arborea, Afzelia africana and Triplochiton scleroxylon using two brands of ordinary portland cement manufactured by two different domestic cement companies operating in Nigeria known as Dangote PLC and Lafarge Company. The admixture of wood particles and cement for production of the CBPs were done at mixing ratios of 1:1, 1:1.5 and 1:2 (weight to weight basis). The properties such as water absorption and thickness swelling at 24 hours, density, modulus of rupture (MOR), modulus of elasticity (MOE) and impact bending strength were determined. The results of the study reveal that the density ranged from 0.61 to 0.92 g/cm3. Meanwhile, water absorption and thickness swelling were found to be 30.34 to 72.44 % and 11.43 to 10.77 % at 24 hours, respectively. The bending properties obtained from the laboratory tests ranged from 115.77 to 826.55 N/mm2 and from 1157.70 to 4773.38 N/mm2 for MOR and MOE, respectively, while impact bending strength ranged from 41.70 to 238.49 N/mm2, respectively. As the cementious content increases from 50 % to 66.3 % and wood content decreases from 50 % to 33.4 %, the properties such as density, MOR, MOE and impact bending strength increased, while water absorption and thickness swelling decreases. The statistical results showed that such factors as wood species, cement type and mixing ratio had significant influence on the physical and mechanical properties of CBPs. The study reveals that CBPs made of wood particles of Triplochiton scleroxylon and Dangote cement brand at the ratio of 1:2 were more dimensionally stable, denser and stronger while CBPs of wood particles of Afzelia africana were stiffest and most rigid. As concluded, cement brand had significant importance in qualities of CBPs, which can be attributed to chemical compositions found in materials used. Keywords: cement, physical, mechanical, wood, particleboards, mixing ratio

Bioactive Propolis-Silane System as Antifungal Agent in Lignocellulosic-Polymer Composites

Polymer composites with renewable lignocellulosic fillers, despite their many advantages, are susceptible to biodegradation, which is a major limitation in terms of external applications. The work uses an innovative hybrid propolis-silane modifier in order to simultaneously increase the resistance to fungal attack, as well as to ensure good interfacial adhesion of the filler–polymer matrix. Polypropylene composites with 30% pine wood content were obtained by extrusion and pressing. The samples were exposed to the fungi: white-rot fungus Coriolus versicolor, brown-rot fungus Coniophora puteana, and soft-rot fungus Chaetomium globosum for 8 weeks. Additionally, biological tests of samples that had been previously exposed to UV radiation were carried out, which allowed the determination of the influence of both factors on the surface destruction of composite materials. The X-ray diffraction, attenuated total reflectance–Fourier transform infrared spectroscopy, and mycological studies showed a significant effect of the modification of the lignocellulose filler with propolis on increasing the resistance to fungi. Such composites were characterized by no changes in the supermolecular structure and slight changes in the intensity of the bands characteristic of polysaccharides and lignin. In the case of systems containing pine wood that had not been modified with propolis, significant changes in the crystalline structure of polymer composites were noted, indicating the progress of decay processes. Moreover, the modification of the propolis-silane hybrid system wood resulted in the inhibition of photo- and biodegradation of WPC materials, as evidenced only by a slight deterioration in selected strength parameters. The applied innovative modifying system can therefore act as both an effective and ecological UV stabilizer, as well as an antifungal agent.

Additive manufacturing of post-process thermoformed wood-plastic composite cladding

To offer extruded Wood-Plastic Composite (WPC) cladding more design options, they could be thermally reshaped in an industrial post-process. However, there is little knowledge about how temperature, heating time, bending radius and fibre content impact mechanical properties and memory behaviour after thermoforming. Therefore, two compound formulations with different wood contents were investigated. While higher heat facilitates forming with smaller radii, strength significantly decreases, especially for thicker samples. In contrast, stiffness is less affected. Retention forces increase with narrow curving, but lower fibre contents counteract this. In contrast to heating duration, temperature tends to produce compound-independent reactions during conditioning, and among geometric parameters, the shaping radius exerts universal responses, more than the material thickness. The fibre content, as a compound-specific factor, affects the material behaviour entirely. For implementation on industrial scale, rupture modulus and retention force should be used for development and process control, whereas research should aim at compound optimisation.