Cell Lumens Research Articles

Influence of Anatomical Spatial Architecture of Pinus devoniana on Pressure Gradients Inferred from Coupling Three-Dimensional CT Imaging and Numerical Flow Simulations

Conifer forests in Michoacán are facing climate change. Pinus devoniana Lindley, with natural distribution in the state, has shown certain adaptability, and knowing the influence of anatomy in the flow system is essential to delimit how it contributes to safety margins and water efficiency. For this, the pressure gradients in the cell lumens and their ramifications were analyzed by numerical simulations of flow throughout the real microstructure. Xylem were evaluated in radial, tangential and longitudinal directions. With the skeletonization of lumens and their constrictions, a branching system of interconnection between tracheids, ray cells, intercellular chambers, extensions, and blind pits were identified. In the simulation, the branched system bypasses the longitudinal fluid passage through the pores in membranes of pairs of pits to redirect it through the direct path branching, contributing to safety margins and water efficiency. Thus, resilience at low pressures because of the lower pressure drop in the extensions. The interface between the branching system and the cell lumens are sites of higher pressure gradient, more conducive to water-vapor formation or air leakage in the face of the lowest pressure system. The flow lines move along easy paths, regardless of the simulated flow direction. Deposits in the cell extensions were shown to be attached to the S3 layer of the cell wall, leaving the center of the duct free to flow. It is concluded that the spatial architecture of the xylem anatomy of Pinus dvoniana is a factor in the resilience at low pressures due to high water stress of the species.

Softening beech wood with Fe3+ auxiliary deep eutectic solvent (DES)

ABSTRACT Deep eutectic solvents (DES) offer advantages such as environmental friendliness, recyclability, and biocompatibility, demonstrating promising applications in functional materials, chemical reactions, and electrochemistry. This study investigated the softening effect of DES on beech with the assistance of FeCl3, considering different treatment durations (1, 2, 3, and 4 h) on varying thicknesses (1, 2.5, 3.5, and 5 mm). Results indicate that longer treatment time leads to better softening effects on beech wood at the same thickness. FeCl3 acts as an active site providing acidic protons, thereby enhancing the softening efficiency of DES. Wood treated with Fe3+-assisted DES removes 86% of the lignin and 48% of the hemicelluloses, resulting in enhanced flexibility. Scanning electron microscopy reveals that most of the vessel lumens, cell lumens, and intercellular spaces of beech wood treated with Fe3+-assisted DES are filled with DES, reducing the wood's porosity. Color difference analysis and energy-dispersive X-ray spectroscopy demonstrate that wood color darkens gradually with prolonged treatment time, correlating with the addition of FeCl3. Thermal analysis indicates an improvement in the flame retardancy of the treated wood. This research methodology significantly enhances wood utilization and diversifies the aesthetic possibilities of wood products, thereby may expanding their applications in architecture and furniture.

Effects of the ice formation and its content on viscoelastic characteristics of wood exposure to low temperatures ranging from −125°C to 25°C

ABSTRACT The influence of ice formation and its content on the viscoelastic characteristics of wood were investigated in the temperature range between −125°C and 25°C. The stiffness and damping properties of the longitudinal (L), radial (R) and tangential (T) specimens were determined for different moisture content (MC) levels at or above the fiber saturation point (FSP) ranging from 25% to 300%. Results showed that the E′ value was correlated negatively with temperature for all specimens. Accompanied by the frozen free water inside the wood, the order of magnitude in E′ for specimens in the different anatomical directions trend toward an accord. The increment in E′ (ΔE′) of specimens was correlated positively with the ice content, and ΔE′ in the L direction was lower than those in the R and T directions at each MC level. The γ-relaxation ranged from −112.9°C to −94.8°C was observed for all orthotropic directions at 10 Hz, which was assigned to the reorientation of methylol groups and adsorbed water molecules in the wood cell walls. At each MC level, a lower peak temperature of γ-relaxation was observed in the L specimens compared to the transverse specimens. Notably, the γ-relaxation peak temperature in the E″ and tanδ spectrum showed obvious frequency-dependence, and the apparent activation energy (ΔH) of γ-relaxation over the measured MC range was about 38.08∼69.57 KJ/mol. The ΔH value was close for specimens in orthotropic grain orientations, indicating that this γ-relaxation phenomenon was not affected by its orthotropic structure and also related closely with the formation of ice in the wood cell lumens.

Oriented Interpenetrating Capillary Network with Surface Engineering by Porous ZnO from Wood for Membrane Emulsification.

Membrane emulsification technology has garnered increasing interest in emulsion preparation due to controllable droplet size, narrower droplet size distribution, low energy consumption, simple process design and excellent reproducibility. Nevertheless, the pore structure and surface engineering in membrane materials design play a crucial role in achieving high-quality emulsions with high throughput simultaneously. In this work, an oriented interpenetrating capillary network composed of highly aligned and interconnected wood cell lumens has been utilized to fabricate an emulsion membrane. A novel honeycomb porous ZnO layer obtained by a seed prefabrication-hydrothermal growth method was designed to reconstruct wood channel surfaces for enhanced microfluid mixing. The results show that through the unique capillary mesh microstructure of wood, the emulsion droplets were smaller in size, had narrower pore-size distribution, and were easy to obtain under high throughput conditions. Meanwhile, a well-designed ZnO layer could further improve the emulsion quality of a wood membrane, while the emulsifying throughput is still maintained at a higher level. This demonstrates that the convection process of the microfluid in these wood capillary channels was intensified markedly. This study not only develops advanced membrane materials in emulsion preparation, but also introduces a brand-new field for functional applications of wood.

Development of bentonite-based organo-geopolymer hybrid wood binder

The study addresses concerns associated with formaldehyde-based adhesives in wood panel board production by proposing geopolymer-based wood binders as promising, formaldehyde-free alternatives. Using bentonite, the research delves into the development and performance properties of this geopolymer wood binder. The BET method was employed for the surface characterization of precursor raw materials for binder preparation. Si and Al elements identified through XRF analysis were correlated with characteristic bands in the FTIR spectrum. Alkaline activation solutions, employing sodium silicate and sodium hydroxide with a molar ratio range of 0.5 to 2.5 (SiO2:Na2O), revealed that binders with a molar ratio of 2.5 exhibited lower pH and higher adhesion strength. Different geopolymer formulations at solution to powder ratios (s/p) of 1.33, 3, and 3.5 determined s/p 3.5 as optimal for bentonite-based organo-geopolymer binders. Viscosity, gel time, pH, and solids content were examined, showing the effectiveness of substituting 10% silica fume to enhance the geopolymerization process and improve adhesion. Modifications using citric acid, sucrose, paraffin, pMDI, triacetin, and resorcinol demonstrated wet bonding strength comparable to urea formaldehyde adhesive. Analytical techniques, including FTIR spectroscopy, XRD analysis, and SEM EDX analysis, provided insights into functional groups, crystallographic properties, and microstructural characteristics. The concentration of Si and Al compounds on the bonding line, coupled with Na element diffusion, was observed through these analyses. Light microscopy of lap shear samples revealed a thinner bonding line, affirming effective binder penetration into wood cell lumens in bentonite-based organo-geopolymer binder formulations.

Mechanical characterization and strain analysis applied to the heat treatment of wood materials, by means of digital image correlation

Digital image correlation (DIC) was used to examine the strain distribution of heat-treated beech and Uludag fir woods in mechanical testing. It also evaluated the effects of the heat treatment process on the properties of the wood samples. The physical (mass/density loss, dimensional stability, color change, and surface roughness), mechanical (flexure test and compressive strength), morphological, thermal, and structural properties of the heat-treated wood were examined. It was determined that the heat treatment parameters can be optimized using the DIC method. The test results showed that although heat treatment can provide improved physical and thermal properties, it caused micro-crack formations and collapses in the wood cells. As a consequence, the mechanical properties of the heat-treated wood materials decreased with the heat treatment process. There were slight differences in the curves of the samples according to Fourier infrared and X-ray diffraction analyses. Morphological characterization showed that the heat treatment triggered large cracks in the cell wall and lumens and the morphological structure of heat-treated wood was affected at large percentages.

Effect of compression ratios on the sorption behaviors of bamboo fiber-based composites

The sorption behaviors of bamboo fiber-based composites (BFC) play a critical role on its applications due to its impact on the dimensional stability and biological durability of the material. The sorption behaviors of Neosinocalamus affinis BFC with compression ratios of 1.50, 1.83 and 2.17 were studied in this project, aiming to optimize the manufacturing process of BFC to reduce the sorption of final products. It was found that the hygroscopicity of BFC samples with all three compression ratios is much lower than that of raw bamboo at all the studied relative humidity (RH) levels. The BFC manufactured with 1.50 compression ratios showed the lowest equilibrium moisture content (EMC). The sorption ability of BFC showed some increase with increasing compression ratio especially when the relative humidity (RH) was above 60%. An evolution in moisture absorption model of BFC was proposed based on the changes in its wettability, pore structures, and chemical compositions. Both introduction of phenolic formaldehyde (PF) resin and material densification reduced the water transfer pathway such as bamboo cell lumens, pits, and gaps, as well as the water absorption space in cell wall. Meanwhile, the BFC with higher compression ratio had increased difficulty to absorb water. The increase in sorption ability of BFC with higher compression ratio at high RH environment is proved to be the consequence of the higher content of its mesopore ratio resulting in increased poly-layer water content. Therefore, the RH of application occasions is critical to determine the optical compression ratio of BFC combining with other performance requirements.

Development of gradient-wetting Janus wood membrane with high-efficiency fog collection and oil-water separation

Conventional preparation of Janus membranes with asymmetric wettability focuses on the preparation of extreme hydrophilic side and hydrophobic side, but suffers from pore clogging, low liquid transfer and collection efficiency and short service life. In this study, Janus wood (JW) with a continuous wettability gradient was created throughunidirectional vacuum impregnation of a hydrophobic solvent after the delignification of wood. Digital image correlation (DIC) and layer-by-layer contact angle assessment were utilized to examine the thickness-dependent wettability gradient of the JW membrane. The JW membrane completed the modification of the cell walls without blocking the cell lumens. The presence of wettability gradient in the JW membrane effectively reduced the capillary force of liquid penetration, resulting in decreased adhesion and stagnation of liquid on the membrane surface, and increased flow rate and transport efficiency. Based on the continuous wettability change of the JW membrane, the JW membrane was endowed with the ability to act as a “unidirectional valve” to enable continuous and rapid directional transport of liquids. The mechanical properties of the JW membrane prepared by the unidirectional introduction method were significantly improved, rendering them highly stable and environmentally durable. The fog collection efficiency of the JW membrane was maintained at 97.7% over 10 repeated use cycles. For light oil/water and heavy oil/water mixtures, JW membrane maintained an efficiency of 99.6% or higher. Unlike conventional surface modification methods, the unidirectional introduction method proved practical and effective for modifying the JW membrane in the thickness direction. Furthermore, the prepared JW membrane was sustainable, inexpensive, durable, and environmentally friendly. This study provides a wide range of potential applications in fields such as droplet manipulation, multi-liquid separation, industrial wastewater purification, and microfluidics.

Using optical-electron correlative microscopy for shales of contrasting thermal maturity

Identifying dispersed organic matter (DOM) types present in shales with the help of a standalone scanning electron microscope (SEM) is often difficult to accomplish. Although reflected light microscopes are useful in identifying the organic matter type, they typically achieve magnification of 500× but cannot magnify beyond 2500×. Optical-electron correlative microscopy, a new technique that has recently gained popularity, involves first identifying the type of organic matter under an optical microscope before finding the same particle under SEM for a closer look at its microstructure. In this study, marginally mature in the early oil window (n = 2) and late mature at the boundary of oil window and condensate wet gas window (n = 2) shales from the Rajmahal (RM) and Jharia (Jh) Basins of India, respectively, were compared using the correlative technique. The source rock properties and the mineralogical composition of the shale samples were first evaluated using Rock-Eval 6 and X-ray diffraction (XRD) analysis, respectively. During electron microscopy analysis, SEM parameters such as brightness/contrast levels, acceleration voltage, and working distance were adjusted to make the DOM and mineral matter present in the shale samples clearly distinguishable from one another. At the acceleration voltage of 15 kV under backscattered (BSE)scanning mode and 10 kV under secondary electron (SE2) scanning mode the DOM and mineral matter were clearly discernible in both RM and Jh shale samples. However, without the correlative technique it was challenging to distinguish between the individual maceral types present in the shale samples, as all appear dark under SEM. Mineral matrix characterization using the correlative technique and energy dispersive spectroscopy (EDS) analysis enabled clay minerals in cell lumens of semifusinite to be identified in both RM and Jh shales. Under SEM, pyrite was associated with vitrinite in Jh shales, which was difficult to notice under the optical microscope. The correlative technique enabled the analysis of the organic matter-hosted porosity under SEM at higher magnifications. The sporinite in the RM shale samples was found to have SEM visible pores, whereas no pores were observed to be present within the sporinite in Jh shales. Both vitrinite and inerinite macerals observed in RM and Jh shale samples lacked any SEM-visible pore structure. The pores were found to be more obvious at a 5 kV acceleration voltage than at 10 kV in SE2 scanning mode.

WATER RETENTION OF BEECH SHAVINGS HEAT-TREATED AT LOWER TEMPERATURES

Water retention after 2 hours and 24 hours of soaking in water was determined for beech shavings subjected to heat treatment at temperatures of 120°C, 140°C and 160°C for 2 hours, 4 hours, 6 hours and 8 hours in order to reduce the equilibrium moisture content (EMC) of the wood shavings for use in wood based composites. EMC was determined after 14 days of air conditioning at 23°C and 55% relative humidity. The measured values were compared with the sample dried at 103°C. Water retention was determined after 15 min of centrifugation at 1400 rev.min-1 for a more objective assessment of the wood's ability to retain water in the cell lumens. The results showed that heat treatment reduces the EMC of beech shavings heat-treated at 160°C for 8 hours in the given conditions from 8.7% to 6.19%. The reduction of EMC at lower temperature was not sufficient enough, especially in the shorter treatment duration of up to 6 hours. In parallel, the reduction of water retention from 65.53% to 47.79% was caused by heat treatment for 8 hours at 160°C.

Synergistic improvement to dimensional stability of Populus cathay ana via hemicellulose removal/alkali lignin impregnation

Abstract Poor dimensional stability restricts the commercial utilization of fast-growing wood. In this study, fast-growing poplar (Populus cathayana) was treated by removing hemicellulose with hydrothermal treatment and impregnating alkali lignin via full-cell process, synergistically, for enhanced dimensional stability. After modification, hydroxyl groups were reduced in hemicellulose removed wood (DHC), alkali lignin was observed to fill in the cell lumens of vessels and wood fibers in the impregnated wood (AL) and in the wood modified by hemicellulose removal with alkali lignin impregnation (DHCAL). Compared with untreated wood, the volumetric swelling ratio of DHC and AL decreased by 11 % and 21 % under relative humidity (RH) of 89 %, respectively. The volumetric swelling ratio of DHCAL decreased by over 50 %, indicating a positive synergistic effect. The combination of hemicellulose removal and alkali lignin impregnation treatment improved the dimensional stability of wood significantly by reconstructing wood chemical components with various levels of hygroscopicity. This work could meaningfully contribute to the efficient utilization of fast-growing wood and promote the added value of industrial alkali lignin.

Flame retardancy and physical-mechanical properties of poplar veneers impregnated by calcium carbonate

Fast-growing poplar (Populus tomentosa Carr) can produce wood veneers, but their poor quality restricts their application in construction and building. Modification of wood has the potential to improve its properties. In this study, poplar veneers were impregnated with calcium carbonate (CaCO3) to reinforce their performance. The results showed that CaCO3 was uniformly distributed in cell lumens in impregnated veneers. After impregnation, the maximum weight gain rate was up to 41.4%, and water uptake decreased from 6.82% to 0.94%. The hardness increased from 7.6 to 10.0 MPa, and the extent of wear fell from 0.91% to 0.05%. The ignition time was prolonged, and the heat release rate and total heat release were low. Experimental results demonstrated that CaCO3 improved the physical-mechanical properties and flame retardancy of poplar veneers.

Lignocelluloses-Based Furan-Acetone Adducts as Wood Adhesives for Plywood Production.

Plywood is made of wood veneers that are bonded with adhesives such as urea-formaldehyde, phenol-formaldehyde and melamine-formaldehyde resins. The plywood made from formaldehyde-based adhesives not only releases formaldehyde but also relies on fossil resources. In this article, we synthesized furan-acetone adducts from lignocellulosic biomass in one pot. The furan-acetone adducts could be directly used as adhesives with the addition of phosphoric acid as a curing catalyst. Particularly, with the addition of 5 wt% diphenylmethane diisocyanate (MDI) as a crosslinking agent, both the wet and dry bonding strength of the plywood prepared from the adhesives could meet the minimum requirement of 0.7 MPa (Chinese National Standard GB/T 9846-2015). The possible adhesion mechanism is that the penetration of furan-acetone adhesives into vessels and cell lumens followed by crosslinking during hot-pressing forms mechanical interlocking at the interface of wood veneers, which provides the main bonding strength of plywood. The findings presented here could provide a new way for the efficient preparation of aldehyde-free green wood adhesives and the value-added utilization of woody biomass.

Automated quantification of fluorescence and morphological changes in pretreated wood cells by fluorescence macroscopy

BackgroundLignocellulosic biomass is a complex network of polysaccharides and lignin that requires a pretreatment step to overcome recalcitrance and optimize valorisation into biobased products. Pretreatment of biomass induces chemical and morphological changes. Quantification of these changes is critical to understand biomass recalcitrance and to predict lignocellulose reactivity. In this study, we propose an automated method for the quantification of chemical and morphological parameters through fluorescence macroscopy, which was applied on wood samples (spruce, beechwood) pretreated with steam explosion.ResultsResults in fluorescence macroscopy highlighted the impact of steam explosion on spruce and beechwood: fluorescence intensity of samples was highly altered, especially for the most severe conditions. Morphological changes were also revealed: shrinkage of cells and deformation of cell walls manifested as the loss of rectangularity or circular shape, for tracheids in spruce and vessels in beechwood respectively. Quantification of fluorescence intensity of cell walls and quantification of morphological parameters related to cell lumens were carried out accurately by applying the automated method onto the macroscopic images. The results showed that lumens area and circularity could be considered as complementary markers of cell deformation, and that fluorescence intensity of the cell walls could be related to morphological changes and to the conditions of pretreatment.ConclusionsThe developed procedure allows simultaneous and effective quantification of morphological parameters and fluorescence intensity of the cell walls. This approach can be applied to fluorescence macroscopy as well as other imaging techniques and provides encouraging results towards the understanding of biomass architecture.

Modification of poplar wood cells using 1,3-dihydroxymethyl-4,5-dihydroxyethylideneurea/alkaline lignin for enhanced mechanical properties and decay resistance

Fast-growing poplar wood was modified by using 1,3-dihydroxymethyl-4,5-dihydroxyethylideneurea (DM) and alkaline lignin (AL) to improve its mechanical properties and decay resistance. AL was first used in combination with DM for wood impregnation modification. The weight percent gain, dimensional stability, mechanical properties, decay resistance and microcosmic changes of all wood samples were evaluated systematically. The results indicated that the maximum weight percent gain and anti-swelling efficiency of poplar wood after modification with DM-AL reached 46.2 % and 52 %, respectively. Compared with the unmodified samples, the bending strength, modulus of elasticity and hardness of the wood samples modified with DM-AL increased by 40 % – 60 %. Notably, the impact strength of samples modified with DM-AL was 18–26 % higher than that of samples modified with DM only, which may be due to the fact that the AL macromolecules slowed down the infiltration of DM-AL into the wood cell walls. The decay resistance of optimal modified samples against the decay fungus was improved by ∼80 % compared with unmodified sample. Furthermore, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) confirmed that DM-AL modifiers impregnated into wood cell lumens. Fourier transform infrared spectroscopy (FTIR) demonstrated that the DM resin crosslinked with wood cell walls and AL macromolecules. In general, this study provides a facile, low-cost and green method to improve the comprehensive performance of fast-growing poplar, including mechanical properties and decay resistance.

Electrostatic deposition of TiO2 nanoparticles on porous wood veneer for improved membrane filtration performance and antifouling properties

Wood has been a promising water purifier material on account of its abundant natural transport channels, easy processing, and renewability, which is mainly focused on its utilization in growth direction for effective separation.Wood veneer manufacured from raw wood block has a reversed-tree pore structure, and possesses advantages of low cost, easy fabrication, material saving, and abundant sources. To realize its functionalization and practicable application for membrane separation, modification of wood veneer is prerequisite. Herein, thin wood veneer with disparate utilization direction of wood was developed to design filter membrane loading TiO2 nanoparticles for treatment of dye wastewater. Wood veneer with reversed-tree transport pathways exhibits unique porous structure, and filtering direction and wood growth direction is almost orthogonal generated numerous sinuous channels. Thereout, sufficient area for loading TiO2 nanoparticles and contacting pollutants as well as appropriate water transport pathways at significantly shrinking thickness of wood (the thickness of 0.2 mm) can be provide by these sinuous channels. TiO2 nanoparticles was first modified by (3-Aminopropyl)triethoxysilane with high positive charge, and immobilized on negatively charged wood surface through atmospheric impregnation via strong electrostatic attractive interaction. Vast quantities of exposed TiO2 nanoparticles on wood cell lumens significantly enhance the adsorption ability for dye contaminants, resulting in a high membrane separation performance. The flux of TiO2/wood veneer membrane can achieve high level of 636.94 L/(m2h) with considerable methylene blue removal of 99.9% at 0.01 MPa. Meanwhile, it shows good cycling stability as well as decent flexibility and excellent mechanical strength. Moreover, the designed membrane with photocatalytic function of TiO2 also displays impressive decontaminated and recycling ability. The flux can recover its pre-recession level after 10 h light irradiation. The designed TiO2/wood veneer with simple preparation process and excellent water treatment capacity exhibits promising results for practical wastewater treatment.

Improving the dimensional stability of round bamboo by environment-friendly modified rosin

Round bamboo is an environment-friendly and sustainable building, construction, and furniture material. It presents several advantages, such as high strength-to-weight ratio, pliability, and simple processing technology. However, natural round bamboo has inferior dimensional stability and is difficult to modify because of the hydrophobic substance on its outer layer. In this study, we designed a simple and efficient alkali pretreatment method (6 % NaOH treatment), which could effectively remove the hydrophobic layer from the bamboo surface, as well as significantly improve its permeability for the subsequent impregnation treatment. Round bamboo was impregnated with epoxy-modified rosin and natural rosin with different concentrations. Results showed that parts of the epoxy-modified rosin occupied the cell lumens of the bamboo, even filling the nanopores of cell walls and intercellular spaces (the pore volume of the round bamboo decreased by 84.76 % in 10–140 nm compared with the natural rosin) to exhibit improved dimensional stability (anti-swelling efficiency increased by 33.74 %) and hydrophobicity (contact angle increased, and water absorption decreased by 24.73 %). After impregnating the round bamboo, the modified rosin was physically filled into the vessels, parenchyma cells, and other structures. Meanwhile, the peak at 908 cm−1 indicates the disappearance of the the CO stretching vibration of the epoxy ring, confirming the occurrence of a reaction between the modified rosin and hydrophilic groups in the round bamboo. Therefore, impregnation with modified rosin can markedly improve the dimensional stability of round bamboo. The modified round bamboo exhibits considerable potential for application as a green structural material in an outdoor environment or a special environment with highly variable humidity.

Highly anisotropic metallized wood obtained by filling basswood channels with low-melting-point Sn-Bi alloy

Basswood and Sn-Bi alloy have several complementary properties—the former has a low density, no electromagnetic shielding, poor thermal and electrical conductivity, and low impact toughness, while the latter has exactly the opposite properties. Combining the natural porous structure of basswood with a low-melting Sn-Bi alloy can produce a composite with the merits of both materials. In this study, basswood was pretreated with 5 % ammonia water, and then the Sn-Bi alloy was filled into the cell lumens and vessels without lignin at 138 ℃ and 3000 Pa. After metallization, the density of the basswood increased from 0.5 g·cm−3 to 3.0 g·cm−3, reaching six times its initial value, which also doubled the impact toughness. The total electromagnetic interference shielding effectiveness of the metallized basswood obtained using different filling methods ranged from 45 dB to 70 dB. Heat-transfer simulations and circuit experiments were carried out to investigate the thermal and electrical conductivity of this composite, and the results demonstrated its anisotropic conductivity. These properties showed that the metallized basswood could be used as a functional or structural material in different fields.

Microstructural and Thermo-Mechanical Characterization of Furfurylated Douglas Fir.

Fast-growing wood has become a major source of materials for the wood industry in recent years, but defects have limited its use. Therefore, modification is urgently needed for the more efficient application of wood products. In this study, a 30 to 50% solution of furfuryl alcohol (FA) was impregnated into Douglas fir sapwood. The microstructure and thermal properties of the specimens before and after furfurylation were evaluated by different techniques. The weight percentage gain (WPG) of modified wood increased up to 22.97%, with the polymerized FA distributed in cell lumens and cell walls, as well as chemically bound to wood components. The polyfurfuryl alcohol (PFA) was mainly located in the tracheids, ray parenchyma cells, and resin canals. In addition, the furfurylated cell walls were greatly thickened. Raman spectra showed that modified wood had significant background fluorescence that covered other peaks. Differential Scanning Calorimetry analysis revealed that the cross-linking reaction between FA and wood changed the shape of curves, with no endothermic or exothermic peaks within the programmed temperature. Moreover, Thermogravimetry and Dynamic Mechanical Analysis results both confirmed that the furfurylation increased the thermal stability of Douglas fir. The percentage of the final mass loss of untreated specimen was 80.11%, while the highest one of furfurylated specimen was 78.15%, and it gradually decreased with increasing FA concentration. The storage modulus (E') and loss modulus (E″) of the furfurylated wood were both lower, and the damping factor (tan δ) was higher than the untreated one. When the temperature reaches about 75 °C, the untreated specimen began to soften and deform. At 90 °C, it fractured completely while the furfurylatedone remained stable. This study demonstrated that furfurylation can improve wood properties and elongate its service life.

Synergistic Effects of Nanoclay and Furfuryl Alcohol on Performance of Wood/Polymer Nanocomposites (WPNCs)

This study proposes a green and facile method by combining furfuryl alcohol (FA) and organic montmorillonite (OMMT) to solve the undesirable intrinsic properties and improve the performance of fast-growing wood. Wood/FA/OMMT nanocomposites (WPNCs) were fabricated by vacuum-pressure impregnation of FA/OMMT solution into wood cavities with the followingin situpolymerization to generate an interpenetrating network structure in cell structures. The FA and OMMT were distributed inside cell walls and transition areas between cell walls and cell lumens through SEM-EDXA and CLSM analyses. The resultant WPNCs had enhanced dimensional stability and water resistance ability. The incorporation of FA and OMMT could further improve the mechanical performance and the thermal stability of WPNCs. Therefore, FA/OMMT could synergistically enhance the performance of fast-growing wood.