Wood Matrix Research Articles

Esterification of wood with citric acid and sorbitol: effect of the copolymer on the properties of the modified wood. Part 1: macroscopic changes, fixation of chemicals and impact bending properties

Abstract Wood modification processes based on citric acid in combination with various copolymers have gained in importance in recent years. These processes also include modification with citric acid (CA) and sorbitol, a sugar alcohol, which is currently in the industrial realisation phase in Germany (SorCA) and Norway (CIOL). The modification of wood with sorbitol and citric acid (SorCA) can significantly improve the dimensional stability and durability of the wood. It is hypothesised that the addition of a copolymer may improve the fixation of the chemicals within as well as the flexibility of the modified wood matrix. In this study, the macroscopic changes, the fixation of the chemicals and the impact bending properties of wood modified with CA and SorCA are compared. Both modifications cause a permanent increase in mass (WPG) and volume (CWB). The fixation of the chemicals was comparable for both modifications; at high chemical concentrations, the SorCA polyester fixed slightly better within the wood matrix. Both modifications led to embrittlement of the wood, measured by a decrease in the impact bending strength (IBS). This embrittlement was clearly concentration-dependent and slightly more pronounced for the modification with CA.

Effect of heat treatment on electromagnetic shielding performance of electroless copper-nickel on wood

The wood-based composites have received extensive attention in the field of electromagnetic interference (EMI) due to inherent layered porous structure. In this study, the deposition Ni and Cu-Ni on wood surface and heat treatment temperature were used as variables. The variation law of electromagnetic shielding (EMS) performance of composite materials is analyzed. The results showed that Ni particles were fully filled in the layered porous structure of the wood, and the metal coatings evenly covered the entire wood surface. The Ni content of the wood based composite materials via 260 °C heat treatment was up to 98.04 %. The pore structure was more regular with the increase of the number of deposition Ni. The ideal roughness was 11.33 μm and the conductivity reached a maximum of 46.8 S/cm at 200 °C. The EMS effectiveness of one deposition Ni composite materials showed an increasing trend when the heat treatment was 200 ℃, 220 ℃, 240 ℃, 260 ℃ and 280 ℃, respectively. When the heat treatment temperature is 260 °C, the EMS effectiveness of the wood-based composite material can reach 88.76 dB, and the hydrophobicity can reach 99.55 °. When the temperature is 300 °C, the electromagnetic shielding effectiveness can reach 91 dB, and the hydrophobicity can reach 117 °. The anisotropic internal porous structure of wood matrix and the multi-interface polarization between wood and Cu-Ni are the main reasons for the high EMS performance.

Preparation and application of wood-supported piezocatalyst with high efficiency and stability via partial hydrolysis of wood cellulose and hemicellulose with Lewis acid

The conveniently recoverable piezocatalyst with self-floating and stable performance has drawn wide attention. Herein, MoS2 was anchored on 1-cm-square eucalyptus wood blocks via a facile hydrothermal/solvothermal process to fabricate two floating piezocatalysts, i.e., MoS2/unpretreated wood (MUW) and MoS2/pretreated wood (MPW). FeCl3 solution was used as a Lewis acid to pretreat the wood through partial hydrolyzing cellulose and hemicellulose for an purpose to creat rich micropores for MoS2 loading in the wood and to form MoFe heterojunction. The piezocatalytic properties and performance of the prepared wood were systematically studied. The scanning electron microscopy confirms MoS2 was anchored on wood surface. The macroscopic photos show that MoS2 penetrated through the MPW interior whereas it was only loaded on the wood surface layer. The X-ray photoelectron spectroscopy reveals the shift of Mo 3d and S 2p, verifying the heterojunction formation of MPW. The Fourier transform infrared spectra prove the partial hydrolysis of wood matrix. In comparison to MUW, MPW had excellent piezocatalytic property, wide pH adaptability, convenient recyclability and high stability. Sildenafil and Cr6+ ions could be completely removed in 20 and 15 min, respectively, by MPW. Contrastly, the removal efficiency of sildenafil and Cr6+ by MUW was 78.6 % and 68.3 % in 20 and 15 min, respectively. After five cycles of use, the removal ratio of sildenafil was 62.4 % by MUW and 90.5 % by MPW in 20 min. The mineralization efficiency of sildenafil reached 99.2 % in 30 min by MPW, and various types of N/S-containing intermediates were effectively degraded. The electron spin resonance characterization and active species scavenging experiments displayed that e− and •O2− were major active species responsible for Cr6+ piezoreduction by MUW and MPW, while •O2− and •OH were the dominant species accounting for sildenafil degradation by MUW and MPW, respectively. And •OH was not generated in the MUW piezocatalysis process. MPW had higher piezoelectric current and lower resistance at the electron transfer interface than MUW. Conclusively, this study paves a new pathway for preparing new floating piezocatalysts with easy recyclability and high stability from biomass for wastewater treatment.

Development of Wood-Based functional composites for advanced sensing and energy conversion applications

With the low carbon-driven development of modern intelligent, research towards novel materials is concentrating on the sustainable biomass-based advanced functional composites. The advanced functionalized wood toward sensing, optoelectronic devices, and energy conversion has been contributed to fast electron transport upon temperature or photo stimulus. Fast electron transport has been highly depended on the interfacial adhesion between the functional layer and wood matrix as well as graphitization degree during carbonization, which promote the electronic excitation and jumps. Here, we develop wood-based functional composites for advanced fire warning and energy conversion by loading metal–insulator transition (MIT) function factor (Ti3O5) onto different woods via liquid crosslinkers, and systematically establish the interfacial adhesion-carbonization-electron transport processes and their relationships on the sensing and photothermal conversion properties. Firstly, balsa with high porosity (pore diameter ≈50 μm), low density (0.16 g/cm3) and extractives content (total extractives content 16.27 %) facilitates crosslinker penetration due to the more holding space and lower nonpolar components. A favorable permeation can promote better interfacial adhesion, and the formation of a continuous conductive network of char-layers during carbonization. Secondly, the crosslinker (chitosan) with excellent adhesion (1 level) and char-forming ability (char residues is 21.7 %), facilitates the formation of a compact network of highly graphitized char-layers (ID/IG=0.81), which increases the electrical conductivity (highest conductivity 5.52 × 10-4 S/m). We found that the most sensitive flame trigger time (0.86 s) for fire warning and the highest evaporation flux (1.63 kg m-2h−1) for desalination can be obtained by using balsa which coupled the chitosan as well as the Ti3O5.

Producing sustainable flame-retardant room temperature phosphorescent materials from natural wood assisted by borax

Materials exhibiting room temperature phosphorescence (RTP) and flame-retardant properties show great potential in a wide range of applications. However, such materials were rarely reported. Here, we found that the RTP of lignin is activated by borax. This is because borax forms non-covalent interaction with lignin, enhancing the spin-orbit coupling (SOC) and restricting the vibration of lignin. Encouraged by this result, borax was introduced into a wood matrix (B-wood) to activate the RTP of naturally occurring lignin in a wood matrix with a lifetime of ∼263.1 ms. Moreover, B-wood displays V-0-level flame retardant properties, the highest level in UL-94 standard (typical standard in evaluating flame retardant properties). As a demonstration of potential applications, B-wood was processed into multifunctional wooden materials and films, which simultaneously exhibit flame retardant properties and generate RTP emission.

Microbial diversity and gene abundance in denitrifying bioreactors: A comparison of the woodchip surface biofilm versus the interior wood matrix.

Excessive amounts of nitrogen (N) and phosphorus (P) can lead to eutrophication in water sources. Woodchip bioreactors have shown success in removing N from agricultural runoff, but less is known regarding P removal. Woodchip bioreactors are subsurface basins filled with woodchips installed downgradient of agricultural land to collect and treat drainage runoff. Microorganisms use the woodchips as a carbon (C) source to transform N in the runoff, with unresolved biological impacts on P. This study aims to explore microbial communities present in the bioreactor and determine whether milling woodchips to probe the microbial communities within them reveals hidden microbial diversities or potential activities. Metagenomic sequencing and bioinformatic analyses were performed on six woodchip samples (i.e., three unmilled and three milled) collected from a 10-year-old woodchip bioreactor treating agricultural tile drainage. All samples had similar DNA purity, yield, quality, and microbial diversity regardless of milling. However, when sequences were aligned against various protein libraries, our results indicated greater relative abundance of denitrification and P transformation proteins on the outside of the woodchips (unmilled), while the interior of woodchips (milled) exhibited more functional gene abundance for carbohydrate breakdown. Thus, it may be important to characterize microbial communities both within woodchips, and on woodchip surfaces, to gain a more holistic understanding of coupled biogeochemical cycles on N, P, and C in woodchip bioreactors. Based on these findings, we advise that future microbial research on woodchips (and potentially other permeable organic materials) examine both the surface biofilm and the interior organic material during initial studies. Once researchers determine where specific proteins or enzymes of interest are most prevalent, subsequent studies may then focus on either one or both aspects, as needed.

Phosphorylated and carbamylated Kraft lignin for improving fire- and biological-resistance of Scots pine wood

In this study, Kraft lignin was modified by ammonium dihydrogen phosphate (ADP) and urea for achieving phosphorylation and carbamylation, aiming to protect wood against biological and fire attack. Scots pine (Pinus sylvestris L.) sapwood was impregnated with a water solution containing Kraft lignin, ADP, and urea, followed by heat treatment at 150 °C, resulting in changes in the properties of the Kraft lignin as well as the wood matrix. Infrared spectroscopy, 13C cross-polarisation magic-angle-spinning (MAS) nuclear magnetic resonance (NMR), and direct excitation single-pulse 31P MAS NMR analyses suggested the grafting reaction of phosphate and carbamylate groups onto the hydroxyl groups of Kraft lignin. Scanning electron microscopy with energy dispersive X-ray spectroscopy indicated that the condensed Kraft lignin filled the lumen as well as partially penetrating the wood cell wall. The modified Kraft lignin imparted fire-retardancy and increased char residue to the wood at elevated temperature, as confirmed by limiting oxygen index, microscale combustion calorimetry, and thermogravimetric analysis. The modified wood exhibited superior resistance against mold and decay fungi attack under laboratory conditions. The modified wood had a similar modulus of elasticity to the unmodified wood, while experiencing a reduction in the modulus of rupture.

Optimization of microwave-expanding pretreatment and microwave-assisted extraction of hemicellulose from bagasse cells with the exploration of the extracting mechanism

Hemicellulose is mainly distributed in the tightly packed S2 layer of the plant cell wall and the middle lamella. This rigid microstructure of wood and interactions among hemicellulose, lignin, and cellulose jointly restrict the separation and transformation of hemicellulose in the wood matrix. To address this issue, a method combined with microwave-expanding pretreatment (MEP) and microwave-assisted extraction (MAE) with a NaOH solution was carried out. We found that the MEP could effectively create new pathways for bagasse cells in mass transferring. More specifically, 195 % of the specific surface area (m2/g) with 193 % of the pores (>50 nm) increased after MEP; the SEM images also confirmed that the microstructure of bagasse was modified. MAE could considerably exfoliate hemicellulose from cellulose fiber and accelerate mass transfer. Additionally, we optimized MEP and MAE by using response surface methodology (RSM). The optimal parameters were 370 K, 3.7 min, 1081 W microwave power, and 9.9 wt% NH4HCO3 consumption for the MEP and 1100 W microwave power, 2.5 wt% NaOH concentration, 34.6 min reaction time for MAE, respectively. Moreover, molecular dynamics (MD) simulation suggests that NaOH could significantly lower the work needed to peel off the xylan chain from cellulose nanofibril.

MXene Functionalized Wood Composite Films for Efficient Electromagnetic Interference Shielding and Pressure Sensing

AbstractDesigning ultra‐light, green, and flexible films for efficient electromagnetic interference (EMI) shielding is crucial yet challenging. Herein, laminated Ti3C2Tx MXene nanosheets are prepared and impregnated into a delignified wood matrix to fabricate composite films. Through a facile drop‐casting and densification strategy, highly aligned cellulose fibers are used for regulating the stacking behavior of MXenes, and the MXenes are encapsulated and attached tightly to the cellulose chains through hydrogen bonds. A high MXene loading up to 32.5 wt.% can be realized, and the resultant MXene/wood film exhibits a tensile strength of 260.7 MPa. The EMI shielding effectiveness is calculated to be 55.5 dB (X‐band, 8.2–12.4 GHz), with a normalized surface‐specific shielding effectiveness of 2673.4 B cm2 g−1. Moreover, the superior electrical conductivity and structural robustness of the composite film give it pressure‐sensing properties and show high sensitivity for monitoring diverse human physiological movements.

Characterization of Densified Pine Wood and a Zero-Thickness Bio-Based Adhesive for Eco-Friendly Structural Applications.

This study investigates a sustainable alternative for composites and adhesives in high-performance industries like civil and automotive. This study pioneers the development and application of a new methodology to characterize a bio-based, zero-thickness adhesive. This method facilitates precise measurements of the adhesive's strength and fracture properties under zero-thickness conditions. The research also encompasses the characterization of densified pine wood, an innovative wood product distinguished by enhanced mechanical properties, which is subsequently compared to natural pine wood. We conducted a comprehensive characterization of wood's strength properties, utilizing dogbone-shaped samples in the fiber direction, and block specimens in the transverse direction. Butt joints were employed for adhesive testing. Mode I fracture properties were determined via compact tension (CT) and double cantilever beam (DCB) tests for wood and adhesive, respectively, while mode II response was assessed through end-loaded split (ELS) tests. The densification procedure, encompassing chemical and mechanical processes, was a focal point of the study. Initially, wood was subjected to acid boiling to remove the wood matrix, followed by the application of pressure to enhance density. As a result, wood density increased by approximately 100 percent, accompanied by substantial improvements in strength and fracture energy along the fiber direction by about 120 percent. However, it is worth noting that due to the delignification nature of the densification method, properties in the transverse direction, mainly reliant on the lignin matrix, exhibited compromises. Also introduced was an innovative technique to evaluate the bio-based adhesive, applied as a zero-thickness layer. The results from this method reveal promising mechanical properties, highlighting the bio-based adhesive's potential as an eco-friendly substitute for synthetic adhesives in the wood industry.

Aroma Profile of Grapevine Chips after Roasting: A Comparative Study of Sorbara and Spergola Cultivars for More Sustainable Oenological Production

This study aimed to compare the aroma profiles of Sorbara and Spergola grapevine prunings roasted at different temperatures (120, 140, 160, 180, 200, and 240 °C). One potential application of grapevine prunings is their use as infusion chips to enhance and improve the aging processes of alcoholic beverages and vinegars. Aromatic compounds impart unique flavors and contribute to the complexity of the final products. Thermogravimetry–mass spectrometry coupled with evolved gas analysis (TGA-MS-EGA) was conducted to identify the thermal steps at which substantial changes occurred in the wood matrix. Solid-phase microextraction–gas chromatography–mass spectrometry (SPME-GC-MS) was used for the analysis of volatile compounds. Several key volatile compounds were identified, showing variations in their concentrations as a function of cultivar and roasting temperature. Furan derivatives, such as furfural, and phenolic compounds, such as guaiacol and vanillin, were the two main chemical classes of volatile compounds that predominantly defined the aroma of grapevine chips roasted above 180 °C. At lower roasting temperatures, some aldehydes, such as hexanal and terpenes, defined the aroma profiles of the samples. By repurposing waste materials, this application offers a pathway for environmentally conscious viticulture and sustainable practices within the food industry.

Mechanical and Thermal Properties of 3D‐Printed Biocomposites of Polylactic Acid and Thermally Modified Wood Flour with Silver Nanoparticles

AbstractThis study investigates the effects of thermal treatment and silver nanoparticles on the mechanical and thermal properties of additively manufactured wood/polylactic acid (PLA) specimens. The 5 and 10 wt% additions of the wood flour into the PLA matrix are done in the twin screw extruder. The test specimens are produced from the filaments with a diameter of 1.75 mm using 3D printer. The mechanical properties of the 3D‐printed wood/PLA specimens are affected by the wood flour content, thermal treatment of wood, and silver nanoparticles. The 3D‐printed neat PLA specimens have better mechanical properties than the wood flour‐filled PLA specimens. The bending strength of the specimens enhances with increasing wood flour content while the tensile strength decreases. The increases in the mechanical properties reveal that the thermal treatment of the wood improves the compatibility between wood and PLA matrix, which hereby improves the interfacial adhesion. The addition of the silver nanoparticles positively affects the mechanical properties and it is more compatible with thermally modified wood particles as compared to the untreated wood particles.

EFFECT OF ANATOMICAL STRUCTURE ON DIMENSIONAL STABILITY OF LOW MOLECULAR WEIGHT PHENOL-FORMALDEHYDE IMPREGNATED WOOD

This research deals with low molecular weight-phenol formaldehyde (LMW–PF) impregnation on sepetir (Sindora spp), nyatoh (Palaquium spp.), and pisang putih (Mezzettia spp.) woods to determine the effect of different anatomical structure on weight percent gain and dimensional stability improvement. The wood samples were impregnated using LMW–PF solutions with 7, 8, 9, 10, and 11% of concentrations (w/w), vacuum-pressured (–98 kPa, 15 min, 350 kPa, 4 h), and re-immersed in 80°C for 3 h. According to the findings, LMW–PF impregnation reduced coefficient of swelling by 9.64–29.95%, and increased anti-swelling efficiency by 12.24–29.91%. Additionally, the water absorption and thickness swelling reduced by 2.43–38.75% and 15.94–34.21%, respectively, indicating the improvement of dimensional stability. Microscopy and NIR analysis revealed the presence and reaction of LMW–PF within porous wood matrix. The effect of diverse anatomical structures caused complexity on LMW–PF impregnation. Sepetir-treated wood with fewer anatomical barriers resulted in better dimensional stability improvement than others.

High performance aqueous asymmetric supercapacitors developed by interfacial engineering wood-derived nanostructured electrodes

Supercapacitors (SCs) are becoming new candidates in the field of sustainable energy supply. Nevertheless, the unsatisfactory energy density due to the narrow voltage window of the supercapacitor is the main barrier to its practical application. Developing appropriate electrode materials to improve the electrochemical performance of SCs and broaden the operating voltage of supercapacitors are imperative. Herein, compatible interfacial engineering wood-derived nanostructured electrodes for aqueous asymmetric supercapacitors (AASCs) are demonstrated. The 3D carbonized wood matrix serves as a high specific surface area current collector and a porous host for the high capacitive active substance, which is composed of manganese dioxide (MnO2) nanowires and polyaniline (PANI) nanoparticles grown uniformly on the porous wall of aligned microchannels (CW@MnO2 and CW@PANI). The resulting electrochemical exchange reactive sites enable the positive electrode to deliver a high areal capacitance of 729 mF cm−2 at 1 mA cm−2 (369 F g−1 at 0.5 A g−1). The negative electrode delivers a high areal capacitance of 1721 mF cm−2 at 1 mA cm−2 (848 F g−1 at 0.5 A g−1). The areal capacitance of two electrodes is superior to most reported supercapacitor electrodes. Additionally, the assembled CW@MnO2//CW@PANI AASC achieves a desirable energy density (170.84 μWh cm−2 at a power density of 0.5 mW cm−2) because a considerable work function difference between electrodes achieved a 2 V wide voltage window. The results of this study provide a critical benchmark and optimistic incentives to adopt natural hierarchical structures to enhance the performance of new-generation energy-related systems.

Sustainable, recyclable, and highly wear-resistant wood matrix as a new paper-based friction material

Sustainable, recyclable, and highly wear-resistant wood matrix as a new paper-based friction material

Efficient electromagnetic interference shielding of three-dimensional hydrophobic Cu/wood/Cu porous composites

Three-dimensional hydrophobic and efficient electromagnetic shielding Cu/wood/Cu laminated composites were prepared by a simple one-step electroless Cu process. The number of electroless Cu on wood surface and the treatment time of electroless Cu were used as variables. The effects of independent variables in the range from 0.3 ×10−3 to 3.0 GHz (L-band) on the conductivity, water contact angle and electromagnetic shielding effectiveness of the composite were analyzed. The Cu particles are fully filled in the wood hierarchical porous structure, and the metal coating uniformly covers the entire wood surface. After three times of electroless Cu, the conductivity of the composite can reach 7255 S/cm, the contact angle is 130.8° when the time is 12 min, showing good hydrophobic properties, and the average electromagnetic shielding effectiveness is as high as 96 dB. Compared with the L-band (94 dB), the twice electroless sample has a maximum shielding effectiveness of 85.6 dB in the X-band (8.2-12.4 GHz), which can shield a large number of incident electromagnetic waves to achieve high absorption and low reflection. The anisotropic internal porous structure of wood matrix and the multi-interface polarization between wood and Cu are the main reasons for the effective electromagnetic interference shielding performance of Cu/wood/Cu laminated composites.

Green Strategy for Improving the Formation of Reconstituted Wood-Based Composites

In this study, a novel strategy inspired by the low melting temperature of a deep eutectic system (DES) was proposed to improve the efficient formation of reconstituted wood-based composites prepared via hot pressing. Hydrogen bond acceptors were used to prepare DES with lignin and hemicelluloses in a wood matrix in situ to achieve this goal. The feasibility and performance mechanism of this method were investigated in depth. Results show that the glass-transition point, Tg, of the amorphous components could reduce by more than 30 °C after the formation of DES. The dimensional stability and mechanical performances of the reconstituted wood-based composites were synchronously improved. The uniform bonding structure formed due to the efficient distribution of amorphous components (lignin and hemicelluloses) between the bonded interface driven by low-temperature melting of DES was an important reason for this phenomenon. In addition, the re-condensation of the degradation products of the amorphous components in wood also contributed to this. The consumption of a synthetic adhesive for wood interface bonding will be reduced in this situation. This work created a revolutionary approach for the preparation of green wood-based composites.

Improved wear resistance and recycling of carbon fiber/epoxy composites via incorporation of regenerated lignin cellulose

Combining wood matrix with thermosetting resin promises to be a new generation of resin-based friction material alternatives. Herein, regenerated lignin-cellulose (RLC) was prepared by waste wood, and precursor matrix slurry (EP@RLC) was obtained by mixing aqueous epoxy resin (EP) with RLC in different proportions. The impregnation and low-temperature curing processes were used to realize the combination of carbon fibers (CFs) and wood-plastic matrix. RLC filled the voids between CFs and adhered to their surfaces to build a CF-RLC reinforced structure, improving the surface roughness of the CFs/wood-plastic resin-based composite (CFs/EP@RLC) and enhancing the tensile strength and wear resistance. It has excellent mechanical strength with the tensile strength of up to 151.9 MPa, tensile modulus of up to 8.52 GPa, and toughness of up to 9.05 MJ/m3. In the tribological performance test, CFs/EP@RLC showed a stable friction coefficient (0.06) and low wear rate (0.64 mm), and no damage occurred at the interface of CFs after a long period of cyclic testing. In comparison with current research on resin-based friction materials, the CFs/EP@RLC meet the requirements in terms of mechanical and tribological properties. Besides, the CFs contained in end-of-life products can be easily recovered in hot alkaline solutions.

Применение арабиногалактана для минерализации древесины

Formulation and technological solutions aimed at improving the physico-chemical and physico-mechanical characteristics of pine wood construction materials by mineralization of the plant raw materials matrix due to its treatment with an aqueous organomineral suspension based on arabinogalactan and pre-mechanoactivated silica-containing sand have been developed and scientifically substantiated. The natural polysaccharide arabinogalactan isolated from larch wood can act as a stabilizer of aggregation and sedimentation stability of suspension particles for wood processing. Experimental data on the thermal effect calorimetric measurement of the enthalpy of complexation for a series of experimental samples with different contents of a silica-containing component are presented. The results confirming the high efficiency of arabinogalactan as a surfactant have been obtained. The fact of the formation of a chemical bond during the impregnation of wood samples with an organomineral suspension between organic macromolecules (cellulose, lignin, hemicellulose) of vegetable raw materials and silica of the mineral component was found, which contributes to the consolidation of the latter in the structure of the wood matrix. Mineralization of the wood surface with compositions containing arabinogalactan and silica nanoparticles gives an increase in density and hardness, as well as the acquisition of hydrophobic properties and resistance to oxidative degradation. This indicates the possibility of using this composition for petrifying wood. The kinetic description of the complexation process is given, the conditions of stable long-term existence of the complex in an aqueous medium are established. It is shown that the treatment of wood with suspension for 24 hours in a spontaneous mode with a rationally selected composition leads to an increase in the density of vegetable raw materials by 10 %, an increase in strength along the fibers by 80 %, Brinell hardness by 3,4 times. Impregnation of wood samples in autoclave mode with a similar suspension (under an excess pressure of 1,35…1,40 MPa) significantly intensifies the process of mineralization of plant raw materials. Thus, over a time period of 24 hours, the density of wood increases by 70 %, the increase in strength along the fibers was 91 %, Brinell hardness increases by 3,5 times, water absorption decreases by 21 %. It was found that the impregnation of wood with a suspension of the developed organomineral composition does not lead to a change in the geometric dimensions and texture of the samples.

Isolation and purification of high-molecular weight hemicelluloses from radiata pine wood chips prior to thermo-mechanical pulp (TMP) production

Abstract A novel thermo-mechanical pulping (TMP) process has been developed to produce a by-product rich in high-molecular weight (MW) hemicelluloses, a potential raw material for barrier coatings and films. This process uses prehydrolysis to solubilise the hemicelluloses followed by chip compression to separate the soluble material from the wood matrix. The pressate from the chip compression stage was dark-coloured and had a high content of high-MW hemicelluloses and lignin. However, isolating the high-MW material from the pressate directly by ultrafiltration was not feasible because of membrane fouling by dissolved lignin and wood extractives, while coloured impurities are undesirable for many potential applications. To solve these problems the pressate was purified using XAD adsorbent resin to remove low-MW lignin, extractives and colour. Ultrafiltration of the purified pressate yielded lightly coloured high-MW hemicellulose with a low content of lignin and well suited for barrier films and coatings.