Volume 15 Issue 2

Six tree species were examined using 1H NMR spectroscopy of sap extracted by supercritical CO2. A metabolomic approach was developed to evaluate the sap extracted from sapwood of Norway spruce (Picea abies), Sitka spruce (Picea sitchensis), radiata pine (Pinus radiata), macrocarpa (Cupressus macrocarpa), and two Eucalyptus species—shining gum and mountain ash (Eucalyptus nitens and Eucalyptus regnans. The sap extraction patterns in the different species were visualised using 1H magnetic resonance imaging. In softwoods with distinct annual rings, water was first removed from the latewood bands, and then gradually from the earlywood bands. In the case of the hardwood species an almost random water redistribution, rather than water expulsion, was observed. Analysis of the principal component analysis loading plots showed that the significant differences in the sap between each species were due to the carbohydrate region. Key discriminators were identified as pinitol, sucrose, glucose, and fructose.

Information to support efficient log procurement decisions based on log cost as well as volume and value of veneer produced from log volume is scarce. The objective of this study was to systematically investigate the effect of log dimensions and geometry (small-end diameter under bark (SEDUB), taper, sweep, and ovality) on the recovery of marketable veneer from log volume, and to produce a metric to support efficient log procurement decisions. The metric developed was the maximum that could be paid for mill-delivered logs of a specific log geometry (MDLCmax) while attaining a target gross margin. In decreasing order of impact on the net recovery of marketable veneer from log volume, the log characteristics were sweep, SEDUB, taper, and ovality. In an Australian case study, log dimensions and geometry were found to substantially affect MDLCmax. Relative to a 2.6-m cylindrical log, taper of 0.01 m/m of log length decreased MDLCmax $10/m3 and sweep of 0.01 m/m of log length decreased MDLCmax $20/m3. This metric is useful for supporting log procurement decisions of the timber industry.

Alkali lignin (AL) fibers with a smooth surface and fine morphological appearance were successfully produced via electrospinning using a simple heated single spinneret system, instead of typical electrospinning of lignin with added synthetic polymer blends or conventional co-axial electrospinning. To reduce the size of the fibers, glycerol was added to the spinning solution as a co-solvent for surface tension reduction and electrospinnability improvement. After electrospinning, stabilization and carbonization were subsequently performed to convert AL fibers to carbon fibers (CFs). The obtained CFs displayed rough and uneven surfaces. However, the CFs derived from glycerol-added solution showed greater electrical conductivity, specific surface area, and porosity compared with those from pure AL solution. Furthermore, the results indicated that the inorganic salts on the rough surface of CFs were successfully removed by sulfuric acid (H2SO4) washing. After H2SO4 washing, the CFs revealed a smoother surface and higher electrical conductivity, specific surface area, and porosity.

To understand the effects and the mechanism of sodium carbonate (Na2CO3) addition on the bagasse alkaline black liquor (BABL) pyrolysis, the reaction variables such as temperature, heating rate, and amount of Na2CO3 addition into BABL-solids were investigated under N2 atmosphere from 50 °C to 1000 °C by thermogravimetic analysis (TGA). Scanning electron microscopy (SEM) and the Coats–Redfern method (CRM) were employed for surface microscopic morphology observations and kinetic analysis, respectively. The results showed that Na2CO3 plays an inhibiting and promoting role during devolatilization (200 °C to 650 °C) and the reduction stages (650 °C to 1000 °C), respectively. Adding Na2CO3 into BABL-solids tends to increase the thickness of the salt layer covering the BABL-solids surface, which increases the activation energy and reduces the weight loss ratio of BABL-solids pyrolysis within 200 °C to 650 °C. Adding Na2CO3 into the BABL-solids tends to increase the number of alkaline compounds or the active site of the reduction reaction, which reduces the activation energy and increases the weight loss ratio of BABL-solids pyrolysis within 650 °C to 1000 °C. The role of Na2CO3 as an additive could be well understood by studying the influence mechanism of Na2CO3 on BABL-solids pyrolysis.

Excessive exploitation of petroleum-based plastics and synthetic fibers is harming the environment. This study isolated nano-fibrillated cellulose (NFC) from plant fiber (Agave americana). The as-extracted Agave fibers were chemically treated (alkali, bleaching, and acid hydrolysis coupled with ultrasonication). Functional and structural analysis were performed using Fourier-transform infrared spectroscopy and X-ray diffraction. The surface morphological changes and thermal decomposition behavior were studied by scanning electron microscopy and by thermogravimetry and derivative thermogravimetry, respectively. Fourier-transform infrared peaks confirmed the absence of lignin and hemicellulose in the NFC samples. X-ray diffraction data revealed that the crystallinity index increased from 50.1% to 64.1% from the raw fiber to the NFC. Thermogravimetry and derivative thermogravimetry showed that the stability increased notably from the raw fiber to the NFC stage. The average particle size was 18.2 nm ± 10.14 nm in the NFC sample, which was confirmed by transmission electron microscopy.

Cellulose–silk fibroin (CSF) films were prepared by blending cellulose and silk fibroin (SF) in different ratios (10:0, 10:3, 10:6, 10:9, and 10:12 wt%) in 60% LiBr aqueous solution. All of the blend films were transparent, and their coloration gradually increased with increasing SF content. Interestingly, cross-sections of all of the tested films were observed by scanning electron microscopy and exhibited similar morphologies. The silk II structure was not well developed in the CSF; however, regenerated SF affected the crystal structure of the cellulose and formed intermolecular hydrogen bonds with cellulose. EDS mapping showed that cellulose and silk in the film were distributed uniformly. The mechanical properties of the dry-state film was greatly improved with the addition of an appropriate amount of SF. In contrast with the dry-state films, the films in the wet state exhibited smaller tensile strengths and E-modulus as SF content increased; however, the elongation values were higher than those in the dry-state films.

The results of the post-culture fungicidal medium from Trichoderma viride Pers. and Alternaria alternata (Fr.) Keissl. mold fungi and Acetobacter xylinum bacteria were studied relative to selected fungi belonging to Basidiomycetes, which cause wood decay. The obtained results confirmed that post-culture liquids derived from the cultivation of various microorganisms might have a differentiated fungicidal effect on wood-decaying fungi. The lowest concentration of fluid from A. xylinum culture added to the growth medium of the studied fungi that completely inhibited the growth was 5mL/100mL.The fungicidal effect of the liquid from the mold fungus culture on the tested wood-decaying fungi turned out to be definitely low. Trametes versicolor (L.) Lloyd proved to be the most sensitive species. Pleurotus cornucopiae (Paulet) Rolland showed complete resistance to the liquid added to the growth medium, derived from mold fungi. The A. xylinum bacterial culture-fluid may be subject to further analysis as a natural biocide in protecting wood against wood-decaying fungi.

This study deals with the identification of the topography of the surface that is created by machining composite materials with natural fibres (biomaterials, wood-plastic composites – a material with plastic matrix and natural reinforcement). The final surface was evaluated based on tool geometry (turning technology), and the influence of the tool on selected evaluating parameters of the obtained surface was evaluated using a non-contact method, applying an optical profilometer (MicroProf FRT). After machining the surface, characteristic relief (a trace on the surface of the material) was visible depending on the machining factors combination (machine, tool, workpiece, and fixture). The initial material also played a prominent role in the surface monitoring, in relationship to the composition of the material and the interaction between the matrix and reinforcement, i.e., detection of defects in the area of the interaction between the initial components.

There is a current and pressing need to develop engineering standards for timber- and other wood-based mats. In 2018 a group of mat producers and users began discussing a potential grading specification standard specific to mats. There are large gaps in the literature regarding the performance of the available raw materials as well as bolt-laminated mat systems. This work represents a novel attempt to begin to assess the mechanical properties of timber mats. Eight-inch deep mixed hardwood timbers were graded according to an experimental specification standard. Then, they were drilled and bolt laminated into 28 three-timber composite mats that were 24 inches (60.96 cm) in width. The bending stiffness (modulus of elasticity [MOE]) and strength (modulus of rupture [MOR]) performance were evaluated with a static bending test. The 5th percentile nonparametric tolerance limit (5% NTL) and design value for fiber stress in bending (Fb) were calculated. The nonparametric design value compared favorably with that of graded timbers, as described in the 2018 National Design Specification (NDS) for wood.

Biomedical researchers have been attempting to construct a wound dressing with the structure and function of a bionic natural extracellular matrix. This dressing would provide a comfortable environment for wound self-healing. In this study, cellulose-collagen fibrous networks were easily fabricated via the one-pot method using genipin in situ crosslinking collagen hydrolysate in cellulose nanofibrous membranes made by electrospinning cellulose acetate and subsequent deacetylation. The morphology, properties, and successful entrapment of collagen in the cellulose fibrous dressings were validated by scanning electron microscopy, element analysis, Fourier transform infrared spectroscopy, X-ray diffraction, water-swelling test, and thermal gravimetric analysis. The functional cellulose nanofiber-based composite membranes exhibited a network structure, good thermal stability, and acceptable water resistance. Human epidermal cells seeded on the composite nanofibrous membranes presented favorable growth, indicating good cytocompatibility and suitability of the dressing to the wound. Therefore, these novel cellulose-collagen fibrous networks may have potential use in biomedical applications.