Article

Development of Modified Wood Products Based on Furan Chemistry

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Abstract

The first processes for “furfurylation” of wood (wood modification with furfuryl alcohol) were developed several decades ago. Furfuryl alcohol is a renewable chemical since it is derived from furfural, produced from hydrolysed biomass waste. Over the last decade modernised processes for furfurylation of wood have been developed. These new processes are based on completely new catalytic systems and process additives. The properties of furfurylated wood depend on the retention of grafted/polymerised furfuryl alcohol (PFA) in the wood. At high modification levels (high retention of PFA) the enhancement of a wide variety of properties are achieved: an exceptional hardness increase, exceptional resistance to microbial decay and insect attack, high resistance to chemical degradation, increase in MOR and MOE, and high dimensional stability. At lower modification levels many property enhancements also occur, however to slightly lower extent. Notable are resistance to microbial decay and insect attack, increase in MOR and MOE, and relatively high dimensional stability. Two main processes for production of furfurylated wood have been developed for Kebony ASA (Former Wood Polymer Technology ASA) by the authors. Kebony for hardwood modification and VisorWood for soft wood modification, where the name reflects the colour of the material produced by the process. Commercial production according to the Kebony process has been running since October 2003, mainly for flooring. A small Kebony production plant is now in operation in Lithuania. A Kebony/VisorWood production plant was started during of 2003 in Porsgrunn, Norway. There are now planed for an expansion of this plant, and plans for a large Visorwood plant is ongoing. Further commercialisation of the technology will be done through licences issued by Kebony ASA.

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... Furfuryl alcohol (FA) can be formed through the hydrogenation of pentosans that are present in agricultural by-products and has been successfully utilised for the chemical modification of wood (Schneider 1995, Westin 1996, Westin et al. 1998, Lande et al. 2004a, Nordstierna et al. 2008, Lande et al. 2008a, 2008b. The FA polymer reacts with itself and possibly reacts with cell wall lignin (Lande et al. 2004a, 2008a, Nordstierna et al. 2008, Gérardin 2016, Li et al. 2016. ...
... A tendency towards lower water absorption of wood was observed after FA-NPsAg treatment compared to FA treated wood, however it was only statistically significant for V. ferruginea and C. alliodora (Table 2). The reduced water absorption can be attributed to the reduction of water flow inside wood (Lande et al. 2008a) because of FA treatment but also to the fact that furfurylation neutralises OH groups, thus reducing hygroscopicity of wood (Baysal et al. 2004, Lande et al. 2008b, Sandberg et al. 2017. Additionally, Xie et al. (2013) indicated that water absorption occurs at certain WPG levels, without reporting more details. ...
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The purpose of the work was to assess the combined effect of furfurylation, along with the addition of silver nanoparticles (NPsAg), on the thermal stability, density, water absorption, hardness and biological durability of juvenile tropical woods originating from Costa Rican forest plantations. It was demonstrated that the weight percentage gain (WPG) of wood treated with furfuryl alcohol (FA) varied from 14.44% to 44.26%, and from 12.92% to 44.52% after the addition of NPsAg. Additionally, for species with WPG over 25%, thermal stability as well as durability was greater, while water absorption was lower, compared to species with lower WPGs. Improvement of hardness was only achieved with WPG values over 35%; therefore, only species of high permeability (V. ferruginea, V. guatemalensis, C. odorata, S. saman and E. cyclocarpum) showed improvement regarding this property. The addition of NPsAg induced the same behaviour as when using plain FA treatment, however, regarding wood durability, the addition of NPsAg was effective only for species with WPG under 20%.
... When the content of acetyl was 18.5%, the control effect on all kinds of rotten bacteria was the best. The effect of wood acetylation on the protection of Marine borers was not obvious, but the degree of wood acetylation decreased with the increase of the acetyl content [39,41,42]. Behbood Mohebby [43] studied the ability of acetylated wood to resist microbial infestation in field soils and observed that soft rot fungi dominate in field soils, and they are one of the important causes of degradation of acetylated and nonacetylated wood. ...
... Soaking the wood under normal pressure can obtain a better anti-corrosion effect. The research on the modification of wood with furfuryl alcohol was initiated by Dr. Alfred Stamm, the pioneer of wood modification in the early 1950s [41]. Irving Goldstein [42,44] conducted an early study on the furfurization of wood. ...
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As a green material, wood is widely used in building decoration, railway construction, and other fields. However, the wood itself has inherent defects of being easy to absorb water and deform, rot, and decrease in strength. The physical and mechanical strengths and stability of artificial fast-growing forest wood are even worse. As wood modification can improve the dimensional stability, durability, strength, and other properties of wood, it has been widely used. Chemical modification is the main method of wood modification. The development of nanotechnology has brought more possibilities for wood modification. Owing to the extensive literature available, this article summarizes the representative achievements of wood chemical modification and nanotechnology. The principle, production process, advantages, and disadvantages of various wood chemical modification methods were analyzed, compared, and evaluated. Finally, according to the application status of wood-modified materials, the problems existing in the current wood chemical modification methods and the application of nanotechnology, and the development trend in the future are analyzed.
... The furfurylation treatment has a much more significant effect on compressive strength than both MOE and MOR. Furfurylation treatment can improve durability against fungal decay [11,13,14], termites [15], marine borers [16], and weathering [17]. Recent studies regarding ecotoxicology and leachates from furfurylated wood have shown that furfurylated wood generally has a low ecotoxicity [9,14]. ...
... Furfurylation treatment can improve durability against fungal decay [11,13,14], termites [15], marine borers [16], and weathering [17]. Recent studies regarding ecotoxicology and leachates from furfurylated wood have shown that furfurylated wood generally has a low ecotoxicity [9,14]. ...
Article
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Short rotation teak wood has low quality especially in dimensional stability and durability. Furfurylation treatment was applied to improve technological properties of the short rotation teak wood. The purpose of the study was to improve dimensional stability and durability through furfurylation treatment. Short rotation teak sapwoods (Plus Perhutani and Biotrop teaks) were treated through the impregnation process of 45% of furfuryl alcohol (FA) and 5% of tartaric acid as catalyst followed by heated in oven at 120 °C for 16 h under nitrogen atmosphere. Dimensional stability was characterized by volumetric swelling, anti-swelling efficiency (ASE), water uptake (WU), and bulking effect (BE), meanwhile decay durability was determined by the weight loss (WL). The results show that ASE increased in the average of 64%, WU decreased in the average of 59%, and BE increased in the average of 11%, which indicated the improvement of dimensional stability. Weight losses of furfurylated teak woods due to fungal decay of Coriolus versicolor (CV), Pycnoporus sanguineus (PS), and Coniophora puteana (CP) were in the average of 2%, 1%, and 1%, respectively, which categorized their durability to be class 1 (very durable). The increase of lignin content showed by Klason lignin content measurement and Fourier Transform Infrared (FTIR) and Carbon 13 Nuclear Magnetic Resonance (¹³C NMR) analysis indicated that the reaction of FA with lignin occurred after furfurylation treatment. Furfurylated sapwood presented also better thermic stability compared to untreated wood by Thermogravimetric Analysis (TGA). The FA treatment can be applied for improving the quality of short rotation teaks for high quality wood product utilization.
... In recent years, furfuryl alcohol (FA), which can be obtained through the hydrogenation of pentosans present in agricultural by-products, has been successfully implemented in wood chemical modification (Schneider 1995, Westin 1996, Westin et al. 1998, Lande et al. 2004, Nordstierna et al. 2008, Lande et al. 2008a, 2008b, Li et al. 2016, Mantanis 2017. Actually, the researchers M. Schneider (University of New Brunswick) and M. Westin (SP Sweden, RISE), separately, developed during the 90's, alternative catalysts for the furfurylation process, i.e. cyclic carboxylic anhydrides mainly maleic anhydride (Li et al. 2016, Mantanis 2017). ...
... The furfurylation technology, which developed by Schneider and Westin, widely known today as furfurylation, is considered as an impregnation modification process, since it is believed that furfuryl alcohol is not chemically bound to the polymeric constituents of wood (Hill 2006, Rowell 2012). However, Lande et al. (2004Lande et al. ( , 2008a have conceived that there should be a grafting reaction between lignin and furfuryl alcohol. Other scientists postulate that furfurylation involves a chemical modification, since FA polymer reacts with itself and possibly reacts with lignin in the cell walls of wood (Gérardin 2016, Li et al. 2016. ...
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This work focused on the upgrading of non-durable tropical wood species originating from fast-growing plantations of Costa Rica. Modification of such tropical woods with furfuryl alcohol, although has not been broadly studied up to date, offers a potential way to increase their low durability. The purpose of this research was to investigate the modification effects on cell wall, vessels wall, radial and axial parenchyma using confocal laser scanning microscopy (CLSM) as well as the changes in the bands of chemical composition using Fourier-transform infrared spectroscopy (FTIR). In fact, nine tropical wood species such as Cedrela odorata, Cordia alliodora, Enterolobium cyclocarpum, Gmelina arborea, Hieronyma alchorneoides, Samanea saman, Tectona grandis, Vochysia ferruginea and Vochysia guatemalensis were treated with plain furfuryl alcohol (FA), and furfuryl alcohol combined with silver nanoparticles (FA-NPsAg). Furfurylation effects were also assessed by the weight percentage gain (WPG) of wood. Results showed that WPG varied from 14.4% to 44.3% with the FA treatment, and from 12.9% to 44.5% with the FA-NPsAg treatment. In the species which exhibited a WPG over 25% with the FA treatment, fluorescence at 600 nm band occurred mostly in the cell walls of fibres, while the furfurylation degree in radial and axial parenchyma was limited. Moreover, furfurylation occurred in lesser extent in wood species with high abundance of axial parenchyma as revealed by fluorescence. Wood species such as Vochysia ferruginea, Vochysia guatemalensis, Cedrela odorata, Samanea saman, Enterolobium cyclocarpum, which showed WPGs>25%, evidenced considerable changes in the lignin structure as observed in the FTIR spectra. In particular, with the FA treatment, the changes were observed in the bands of 1711, 1652, 1561, 889, 796 and 733 cm–1, whereas, with the FA-NPsAg treatment, the changes occurred in the bands of 1711, 1505, 1426, 1370, 1224 and 1016 cm–1. Overall, no significant difference was found in FTIR spectra and anatomical fluorescence between the FA and FA-NPsAg treatment, probably because the NPsAg concentration was insufficient for a change to occur in the bonds.
... On account of this natural delignification process, the lignin content decreases and the wood becomes whitish or slightly yellowish with the separation of fibrils and the formation of voids or cracks. Then, some other serious problems such as accelerated deformation and biodegradation can be generated (Brelid et al. 2000;Hill 2006;Lande et al. 2008;Venås and Rinnan 2008;Sharratt et al. 2010;Esteves et al. 2011;Lin et al. 2018). ...
... The environmental impact is very small as accounted by low leachability and less emission of volatile organic compounds and polycyclic aromatic hydrocarbons (Lande et al. 2004;Pilgård et al. 2010;Yao et al. 2017). Due to its significant property improvement and low environmental impact, furfurylation of wood gains much attention (Lande et al. 2008) and has been developed on an industrial scale and commercialized by several companies from Norway and the United States. ...
Article
Degradation of lignin occurs naturally in wood due to the influence of microorganisms or photic radiation. To improve the properties of wood with low lignin content, furfuryl alcohol (FA) at the concentration of 25% was used to modify poplar wood ( Populus euramericana Cv.) after partial delignification. Moisture sorption and dimensional stability of the samples were investigated under dynamic conditions where the relative humidity (RH) was changed sinusoidally between 45% and 75% at 25°C. Both the moisture content (MC) and the tangential dimensional change varied with a sinusoidal shape similar to the RH. Hygroscopicity and hygroexpansion increased after delignification, while furfurylation led to an inverse impact by reducing MC, dimensional changes, amplitudes of MC and dimensional changes, moisture sorption coefficient (MSC), and humidity expansion coefficient (HEC). After delignification and further furfurylation, the MC and the dimensional changes were reduced by about 20%, and the maximum drop in amplitudes of MC and dimensional changes was about 30%, while the MSC and the HEC decreased by over 15%. In addition, the furfurylated wood with low lignin content exhibited lower sorption hysteresis and swelling hysteresis.
... On the other hand, furfurylation is regarded as a promising method to improve wood properties with growing attention, and it has already been developed on an industrial scale and commercialized by several companies from Norway and the USA [29]. Furfuryl alcohol, as the modifier with small molecular size, can penetrate into the wood cell wall and polymerize into macromolecules under the action of catalysts and heat [3,30] for its strong polarity (high affinity for cell wall components) and good solubility in water. ...
... In addition, furfuryl alcohol is derived from furfural through hydro-treating [31,32], and furfural is usually attained from pentose-rich agricultural residues at a low cost, such as rice hulls, bagasse and corncobs widely growing around the word, which also benefits its industrial application greatly. Concerning the performance of wood after furfurylation, significant improvements in many aspects like dimensional stability [33][34][35], biological durability [36,37] and hardness [29] have been confirmed by many researches. Remarkably, no obvious toxicity can be found in the leaching water and low volatile organic compounds or polycyclic aromatic hydrocarbons are released by combustion of furfurylated wood [30,38], namely furfurylation has a slight impact on the environment. ...
Article
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Hygroscopicity and dimensional instability usually impair the service of wood products. To upgrade the property, fast-growing poplar wood (Populus euramericana Cv.) was treated with furfuryl alcohol at a concentration of 25% combined with low hemicellulose pretreatment. Equilibrium moisture content and dimensional changes were measured within the range of 0–96% relative humidity (RH) at 25 °C. New voids caused by hemicellulose loss suggested by the scanning electron microscope contributed to higher weight percent gain of furfural resin with more obvious bulking of cell walls. The size distribution of mesopores increased after low hemicellulose pretreatment but decreased much more after furfurylation from the analysis of nitrogen adsorption. After hemicellulose loss, moisture sorption was weakened indicated from the decrease in moisture content (MC) and hydrated MC as well as dissolved MC due to the decrement of accessible hydroxyl groups calculated by Hailwood–Horrobin theory. Furthermore, dimensional stability was improved. Furfurylation led to further reduction in moisture sorption and enhancement of dimensional stability, since water paths were blocked and less hydroxyl groups were accessible. The bulking also limited the swelling of cell walls. After the combined modification, over 45% reduction in moisture content and dimensional changes of wood at 60% RH can be achieved. Such upgraded fast-growing wood could be utilized more widely with a longer service life as a potential replacement for traditional high-quality solid wood and helpful with building a more efficient and environmentally friendly material industry.
... Furfuryl alcohol is a renewable chemical because it is derived from furfural, which can be produced from hydrolyzed biomass waste, such as corncobs, bagasse rice hulls, and others (Machado et al. 2016). The properties of furfurylated wood depend on the retention of polymerized furfuryl alcohol (PFA) in the wood (Lande et al. 2010;Yao et al. 2017;Kong et al. 2018). Ecotoxicity tests studies showed low release of non-reacted furfuryl alcohol in the final products (Lande et al. 2004). ...
Article
Numerical modeling was used for mitered joints prepared with wood-based composite members (poly(furfuryl alcohol)) using Linear Elastic Fracture Mechanics (LEFM). The aim was to understand the joint performance under outdoor conditions. Analysis of fracture mechanics properties of wood-based composite is necessary to obtain a good understanding of joint behavior and to predict the reasons for its fracture. The fracture stiffness of furfurylated wood under mixed mode (I/II) was investigated. In both crack systems, the distribution trends of KIC/KIIC with furfurylation changed. The results of corner mitered joints showed that the mixed mode I/II was the effective fracture mode under diagonal compression (DC) and tension (DT) load. Based on the results obtained from fracture mechanics, the structural performance of mitered joints increased with increasing furfurylation level. The model results confirmed the experimental results.
... Furfurylated wood has enhanced mechanical properties, such as compressive strength and hardness, which are close to that of natural tropical wood (Epmeier 2004;Dong et al. 2015;Sejati et al. 2017). In addition, numerous studies show that furfurylated wood has excellent dimensional stability, corrosion resistance, weather resistance, and resistance to biological deterioration (Hadi and Westin 2005;Lande et al. 2008;Esteves et al. 2011;Yang et al. 2019). It is reported that furfurylated wood does not show any toxicity problems exceeding those of natural heartwood. ...
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To address drawbacks of significant toughness decrease of furfurylated wood and comprehensively improve properties of low-quality wood, this study synthesized hyperbranched poly(ester-amide) (HBP) as toughening agent and used synergies of furfuryl alcohol (FA) and HBP for poplar wood modification. The SEM–EDX and FTIR analysis showed that FA and HBP penetrated into wood and in situ polymerized in cell walls and cell lumina, leading to about 25% mass gain and 7% volumetric changes. After compound modification, wood exhibited enhanced hydrophobicity and dimensional stability, suggested by the maximum decrease of over 30% moisture content and volumetric change. This was mainly because polymers blocked water exchanging paths, reduced water accommodation, covered sorption sites and bulked cell walls. The flexural strength and surface hardness of modified wood were notably improved. The impact toughness increased by about 50% compared with that of furfurylated wood, which was mainly ascribed to (1) HBP with a three-dimensional globular structure had micro-phase separation with FA resin during polymerization. The HBP with high flexibility and mobility, acting as the second phase particles, increased the free volume for macromolecular movement. (2) The flexible group-ester group and tertiary amide group of HBP contributed to more absorption of energy and interruption of crack development under impact. Besides, the cracks would be blunted and dissipate impact energy by producing extensive shear deformation. (3) The HBP interrupted the cross-linking of furfural resin and reduced brittle furfural resin network dense. This study provided new references for improving toughness of resin-modified wood and upgrading low-quality wood products for wide application. Graphical abstract
... Scientists have conducted a series of studies on its impregnation performance. As early as in the 1950s, Stamm [3] investigated the use of phenolic and FA to modify wood and made certain progress. Subsequently, wood furfurylation has been a hot topic in the area of improving wood properties, yet the furfurylation reaction was not stable. ...
Article
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Furfurylated wood has many advantages, such as decay resistance, dimensional stability, hardness, etc. However, furfurylation increases the brittleness and decreases the flexural resistance of wood, which greatly limits its application. Therefore, caprolactam (CPL) is incorporated with furfuryl alcohol (FA) to improve the performance of furfurylated wood. In this study, an FA and CPL combinational modifier was used to treat masson pine (Pinus massoniana Lamb.) earlywood and latewood. The synergistic interaction of both components with the wood cell walls was systematically evaluated via microstructural, chemical, and thermal analysis using scanning electron microscopy (SEM), infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectrometry (XPS), and differential scanning calorimetry (DSC). The SEM images showed that polymerized modifiers were distributed in tracheids, ray cells, and pits, with a higher degree of distribution in latewood tissues. The FA-CPL co-treatment led to the highest degree of distribution in cell cavities as well as of cell wall swelling. The results of the weight percentage gain (WPG) of modified wood agreed with the SEM findings that the FA-CPL co-treatment could more effectively increase the WPG than individual modification. The results of FTIR and XPS revealed that FA and CPL might chemically bind with each other as well as react with lignin and hemicellulose in the cell walls during the curing process. In addition, the interactions between modifiers and cell walls were slightly different for earlywood and latewood. DSC analysis indicated that the wood hygroscopicity decreased and the thermal stability improved after modification.
... Furfurylation is an important wood modification technology already in use on an industrial scale [9][10][11][12]. Related to this type of treatment, and considering that the polymerization of furfuryl alcohol depends on several factors, including the nature and the concentration of the catalyst used and the concentration of FA solution [13][14][15], it seems interesting to evaluate the effects of the addition of condensed tannins as a reticulating agent, and of different types of acids as catalysts, to improve the properties of modified wood. ...
Article
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This article presents the effect of the addition of condensed tannins, used as a reticulation agent, on the polymerization of furfuryl alcohol during wood furfurylation, as well as the effect of these condensed tannins on the thermal stability of modified wood. Three kinds of dicarboxylic acids (adipic acid, succinic acid, and tartaric acid), as well as glyoxal, used as model of a wood reticulation agent, were used to catalyze the polymerization of furfuryl alcohol or tannin-furfuryl alcohol solutions. Impregnation of furfuryl alcohol or tannin-furfuryl alcohol solution into the wood, followed by curing at 103 °C for a specific duration, was performed for the wood modification. The thermal stability of the obtained tannin-furfuryl alcohol polymers and their corresponding modified woods was investigated. The leaching resistance and dimensional stability of the modified woods were also evaluated. Results indicated that the partial substitution of furfuryl alcohol by the tannins improved the polymerization reactivity in conditions where furfuryl alcohol alone did not lead to the formation of a solid polymeric material. The thermal stability and leaching resistance of the furfurylated wood in the presence of tannins were improved. Dimensional stability was also improved for furfurylated samples, but the effect of tannin addition was not so obvious, depending on the acidic catalyst used.
... In load-bearing biocomposites, bio-based and biodegradable polymers have recently been studied as alternatives to fossil-based polymers. According to Lande et al. [58], furfuryl alcohol is also a bio-based polymer that can replace phenolformaldehyde resins despite its hazardous properties (monomer and catalysts) and dark hue. Thermosets made from vegetable oils are another bio-based polymer that has been taken into consideration for plant fibre composites [56]. ...
Chapter
Due to its high optical transparency, excellent thermal insulation, and great durability, transparent wood is a desirable structural material for energy-efficient buildings, electronics, packaging, and nanotechnologies. The transparent wood enhances the aesthetic and practical qualities of wood. A lot of work has gone into making transparent wood with luminous, electrochromic, thermochromic, and photo-switchable functionalities by incorporating quantum dots, nanoparticles, or dyes. Because of their superior mechanical qualities and immense potential to function as renewable and CO2-storing cellulose scaffolds for cutting-edge hybrid materials with embedded functionality, wood-derived cellulose materials obtained by structure-retaining delignification are gaining increasing attention. A wide range of characteristics is produced by applying various delignification protocols and numerous additional processes, such as polymer impregnation and densification. Due to the scarcity of bio-based monomers that combine advantageous processing with high performance, the sustainable development of biocomposites has been constrained. Nonetheless, because of its renewable and biodegradable qualities, transparent wood has the potential to replace traditional petroleum-based polymers because of the growing knowledge obtained during the last few years which is presented in the following chapter.
... This change allows the furfurylated short-rotation teak to be more resistant to termite attack than the untreated short-rotation teak. Lande et al. (2008) also reported that furfurylated wood is more resistant to biological attacks owing to chemical reactions with the wood through wood polymer cross-linking. Furthermore, furfurylation also reduces the space available for water within the cell wall, which in itself is to slow down or hinder fungal decomposition (Thybring, 2013;Brischke and Alfredsen, 2020). ...
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Purpose The surface characteristics of thermally and chemically modified wood, such as surface roughness, surface free energy (SFE) and wettability, are important properties that influence further manufacturing processes such as gluing and coating. The aim of this paper was to determine the influence of the surface roughness of thermally and chemically modified teak wood on their SFE, wettability and bonding quality for water-based acrylic and solvent-based alkyd varnishes. In addition, durability against subterranean termites in the field of these modified teak woods was also investigated to give a valuable information for their further application. Design/methodology/approach The woods tested in this study were fast-growing teak woods that were prepared in untreated and treated with furfuryl alcohol (FA), glycerol maleic anhydride (GMA) and thermal. SFE values were calculated using the Rabel method. The wettability values were measured based on the contact angle between varnish liquids and wood surfaces using the sessile drop method, and the Shi and Gardner model model was used to evaluate the wettability of the varnishes on the wood surface. The bonding quality of the varnishes was measured using a cross-cut test based on ASTM 3359-17 standard. In addition, durability against subterranean termites in the field of these modified teak woods was also investigated according to ASTM D 1758-06. Findings The results showed that furfurylated and GMA-thermal 220°C improved the durability of teak wood against termites. The furfurylated teak wood had the roughest surface with an arithmetic average roughness (Ra) value of 15.65 µm before aging and 27.11 µm after aging. The GMA-thermal 220°C treated teak wood was the smoothest surface with Ra value of 6.44 µm before aging and 13.75 µm after aging. Untreated teak wood had the highest SFE value of 46.90 and 57.37 mJ/m ² before and after aging, respectively. The K values of untreated and treated teak wood increased owing to the aging treatment. The K values for the water-based acrylic varnish were lower than that of the solvent-based alkyd varnish. The untreated teak wood with the highest SFE produced the highest bonding quality (grades 4–5) for both acrylic and alkyd varnishes. The solvent-based alkyd varnish was more wettable and generated better bonding quality than the water-based acrylic varnish. Originality/value The originality of this research work is that it provides evaluation values of the durability and SFE. The SFE value can be used to quantitatively determine the wettability of paint liquids on the surface of wood and its varnish bonding quality.
... According to previous results [11,13], the fracture surface of CF was generally smooth, and a significant reduction in impact toughness was caused by furfurylation. This reduction in impact toughness can principally be J Mater Sci ascribed to the dense cross-linking network structures of furfural resin in wood [41]. After combined treatments, the impact toughness of wood was significantly improved. ...
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Upgrading low-quality wood with less consumption of modifier is demanded in sustainable development of wood industry. In this study, multi-interfacial furfurylation combined with densification was proposed to improve performances of wood. Different from traditional furfurylation, the multi-interfacial furfurylation comprised internal impregnation with 10% concentration furfuryl alcohol (FA) and surface coating with reused FA. After combined treatments, FA polymerized on wood surface, and also penetrated into cell lumina and cell walls. Some cell walls became closer and almost attached together. Wood mass increased by 12.6% and density reached 860 kg m⁻³. The set recovery of densified wood decreased by over 92% due to multi-interfacial furfurylation. On account of density increase and multi-interfacial interactions among FA from wood surface to inner parts principally, the mechanical properties were significantly improved with over 260% increase of flexural strength and 50% enhancement of impact toughness. Physical properties were improved indicated by reduction of surface wettability, dynamic moisture sorption and water absorption mainly due to hydrophobicity increase, accessible sorption site decrease, water-path block and accommodation reduction for water molecules. The results can help facilitate better application of low-quality wood for building more efficient and environmentally friendly material industry. Graphical Abstract
... Furfurylation is an important wood modification technology already developed on industrial scale [34][35][36][37]. According to the fact that the polymerisation of furfuryl alcohol depends on many factors, such as the nature and the concentration of the catalyst used and the concentration of FA solution [38][39][40][41], it seems interesting to evaluate the effects of the addition of tannins as reticulating agent and of different types of acids as catalysts to improve fixation of the polymer in the wood. ...
... The impact toughness of CF wood was lower than that of C wood by about 34%. This reduction in impact toughness was principally be ascribed to the dense cross-linking network structures of furfural resin (Lande 2008) and the inhomogeneous distribution of furfural resin in cells (Figure 1), which tended to lead stress concentration under impact loading. Differently, the fracture surface of FG wood was scraggly and some fibers stretched out. ...
Article
Fast-growing wood usually exhibits dimensional instability and inferior mechanical strength, which severely obstructs its wide application. To improve the dimensional stability and mechanical strength, biomass-derived furfuryl alcohol combined with polyethylene glycol (PEG) was vacuum-impregnated into wood hierarchical structures, causing cell wall bulking and porosity reduction. Furfural resin and PEG distributed in cell lumina, cell walls and middle lamella regions indicated by analyses of scanning electron microscope and fourier transform infrared spectroscopy. Wood porosity was generally reduced and the specific surface area decreased by over 65% analyzed by the nitrogen absorption. Consequently, wood hydrophobicity and dimensional stability were highly improved, and the water absorption and volumetric change decreased by over 55% and 78%. The flexural strength and modulus elasticity were improved by over 49% and 46%. Furfural resin helped the fixation of PEG in wood and significantly reduced PEG leaching. PEG with flexible linear molecular structure formed interpenetrating polymer network in wood hierarchical structures with furfural resin and reduced self-crosslinking of furfural resin. Accordingly, the impact toughness of compound modified wood increased by 39% compared with solely furfurylated wood. This study provided efficient and sustainable concepts to facilitate better industrialized application of wood furfurylation and improve service value of fast-growing wood.
... Epmeier et al. (2007 used FA resin for the modification of Scots pine (Pinus sylvestris L.), achieving ASE of the FA modified wood with a WPG of 48% of approximately 60%, and the dimensional stability of the modified wood was significantly improved. Lande et al. (2008a) reported that the dimensional stability of furfurylated wood was positively correlated with the WPG. The WPGs of the FA-modified Scots pine were 32% and 47%, with the corresponding ASEs of 50% and 70%, respectively. ...
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The commercial applications of endangered wood species (e.g., ebony, Indian rosewood, and African blackwood) for string instrument fretboards have been limited due to their low yield, long growth cycle, and tight trade restrictions. However, the physical and mechanical properties of radiata pine modified by furfuryl alcohol (FA) are comparable to the tropical hardwood species that are commonly used for fretboards. Therefore, this study proposes performance indicators of fretboard material selection to evaluate the physical and mechanical properties of modified wood samples with different FA concentrations. The concentration of FA was optimized to make the modified wood satisfy the performance requirements of fretboards. The density of fretboard wood needs to be greater than 800 kg/m3, and have good dimensional stability. The surface color of the wood needs to be dark brown or jet black. The hardness of fretboard wood needs to be greater than 6.0 kN, and it should have superior abrasion resistance (the friction coefficient is about 0.72, and width and depth of the wear scars are 0.8 mm and 25.0 μm, respectively). The E' and GLT{G}_{LT}^{^{\prime}} of the fretboard wood were greater than 9.32 GPa and 1.21 GPa, respectively. The fretboard wood had higher tanδ values and lower υ\upsilon and R values. The results indicated that the density of the 70% FA modified wood was 850 kg/m3, and it had good dimensional stability, which met the physical performance requirements of fretboard selection materials. Only the 70% FA modified wood met the requirements of the main evaluation indicators for the mechanical and sound vibration properties of the wood for fretboards. However, the furfurylated wood had the drawbacks of high brittleness and low bending strength, which needs to be addressed in the future research through FA modification combined with other modification technologies to perfectly replace the fretboard wood species.
... Since the main purpose of an impregnation modification is to improve the dimensional stability of the wood and reduce hygroscopicity, the polymers of interest are designed to not attract water molecules. The main commercial technology in production at the time of writing this paper is the Kebony process, which is based on furan chemistry [412,413]. Other impregnation modification systems which have been commercialised for external use include the use of phenol-formaldehyde (PF) (Lignia) [414], dimethyloldihydroxyethyleneurea (DMDHEU, Belmadur, now called HartHolz) [382,415], neither of which are in production at the time of writing (March 2022). ...
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Timber cladding has been used since historical times as a locally available, affordable weather protection option. Nowadays, interest in timber cladding is again increasing because of ecological reasons as well as naturalistic viewpoints. This review presents a comprehensive report on timber cladding in a European context, beginning with a brief overview of the history before considering contemporary use of timber cladding for building envelopes. The basic principles of good design are considered, paying attention to timber orientation, fixings and environmental risk factors. The relationship of timber with moisture is discussed with respect to sorption behaviour, dimensional instability and design methods to minimise the negative consequences associated with wetting. The behaviour of timber cladding in fires, the effects of environmental stresses and weathering, as well as the cladding properties and the variation thereof with different types of wood and anatomical factors (including exposure of different timber faces), are examined. The review then moves on to considering different methods for protecting timber, such as the use of coatings, preservatives, fire retardants and wood modification. A brief discussion of various environmental considerations is also included, including life cycle assessment, embodied carbon and sequestered atmospheric carbon. The review finishes by making concluding remarks, providing a basis for the selection of appropriate cladding types for different environments.
... Conventional methods including chemical or physical technologies can effectively enhance some performances of wood, like hydrophobicity, dimensional stability and thermal stability (Chang and Chang, 2002;Lande et al., 2008;Wang et al., 2020). However, most approaches still have some challenges because of high production cost and the difficulty in up-scaling, limiting the further application of wood (Xie et al., 2013). ...
Article
Application of wood as a green and sustainable material is restricted due to its easy wrapping property, deformation, biological degradation and thermal instability. Coupling thermal treatment and silica sol penetration could overcome the weakness of natural wood, and synergistically improve the overall performance. Thermal treatment showed a significant effect on hydrophobicity, hygroscopicity, surface color and compressive strength. It reduced the compressive strength to some extent due to the degradation of cell wall polymers (hemicellulose, lignin and cellulose). At above 200 ℃, the degradation of cell wall polymers, rather than hornification, was in the leading position, dominating the compressive strength. Changes in the component and structure of cell walls (chemical and physical environment) helped the penetration and deposition of silica sol owing to extra channels and enlarged pore size. Satisfied silica sol incorporation in thermally treated wood further improved the surface hydrophobicity, dimensional stability, surface hardness, and compensated the reduction on compressive strength. It was attributed to the -OH consumption (cell wall polymers degradation) and filling effect caused by silica sol networks (Si-O-Si and Si-O-C bonds) in wood. The improved thermal stability was ascribed to the coverage effect of silica sol on the inner-surfaces of wood, which could be treated as a physical barrier to prevent heat conduction. Eventually, we proposed a mechanism concerning the combination treatment for preparing silica-mineralized wood. This work opens an eco-friendly way to produce bio-based materials with high quality to be used in outdoor applications or humid environments.
... Therefore, furfurylated wood exhibits relatively lower hygroscopicity. Meanwhile, other properties of wood are also significantly improved, such as dimensional stability, resistance toward biodegradation and anti-weathering efficiency (Lande et al. 2008;Skrede et al. 2019;Li et al. 2020). Importantly, furfurylation is relatively environmentally friendly due to low toxicity and volatile organic compounds or polycyclic aromatic hydrocarbons released after combustion (Lande et al. 2004;Pilgård et al. 2010). ...
Article
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To investigate effects of furfurylation on interactions between moisture sorption and humidity conditioning of wood, Pinus spp. wood was impregnated with furfuryl alcohol solution. After oven drying, furfurylated wood and untreated wood were subjected to two environments where initial relative humidity (RH) was, respectively, about 60% and 80% at 25 °C. Dynamic mass and RH were continuously recorded with a self-assembled device. Furfural resin polymerized in cell walls, cell lumina and some pits, which caused mass gain and cell wall bulking. Furfurylation weakened humidity conditioning performance and hygroscopicity of wood, and the RH increased by over 20.7% while moisture content decreased by over 33.6% for furfurylated wood compared to untreated wood after conditioning at initially about 80% RH. Humidity conditioning process was generally divided into four stages according to changing rate, where RH exhibited sharp increase, slow increase, slight decrease and sub-equilibrium, respectively. Moisture content showed a negative linear relation with RH in the first three stages. This was a result of combined effects of the pressure from water vapor gradient and moisture content gradient, the temperature changes during sorption, the hindrance from capillary systems and attraction of other water molecules. The interaction rate between humidity conditioning and moisture sorption was decelerated for blocking of water passages, reduction in sorption sites and hydrophobicity increase due to furfurylation. Over 45.2% decrease in moisture change rate with RH was caused by furfurylation in the first stage. The study can help in understanding the effects of furfurylation on interactions between moisture sorption and humidity conditioning of wood and facilitate better application of modified wood in human settlement practically.
... Compared with untreated control, the reduction in impact toughness caused by 25 and 50% FA treatments is extremely significant (e.g., 52% reduction after 50% FA treatment), while the reduction caused by 10% FA treatment is insignificant. This reduction in toughness at high FA concentrations is related to the dense cross-linking network structures in the cell wall polymerized by FA (Lande et al. 2008b). Supplementary Figure S2 shows the typical fracture modes of different groups of samples after impact toughness test. ...
Article
In order to explore the application of furfurylated wood as engineering material, polyvinyl alcohol (PVA) was proposed as a toughening agent to incorporate with furfuryl alcohol (FA) to form FA/PVA precursor and impregnate wood in a one-step method. After in situ polymerization upon heating, a hydrophobic network composed of polyfurfuryl alcohol (PFA) and PVA was formed within the wood scaffold. The impact toughness, as well as some water-related properties of modified wood including the contact angle, water absorption, moisture adsorption, and dimensional stability were investigated in this study. The results showed that the impact toughness of wood significantly decreased after furfurylation. The incorporation of PVA could alleviate the reduction, and this effect was more obvious for highly furfurylated wood. PVA could penetrate and bulk the wood cell wall to a certain degree, but increased concentration of PVA may negatively influence the penetration of FA in wood cell wall. PVA showed only slight influence on water-related properties of FA modified wood, and it depended on both concentrations of PVA and FA. All results indicate that incorporation of PVA in FA system is a promising approach to enhance the toughness of FA modified wood.
... Wood furfurylation is generally based on the impregnation of FA, followed by in situ polymerization at elevated temperature in the presence of acid catalyst, which leads to a firm filling of furfuryl resin in wood cavities and cell wall (Xie et al. 2013). As a result, various wood properties including dimensional stability (Yang et al. 2019), biological durability (Skrede et al. 2019), and hardness (Lande et al. 2008) are greatly improved. It is also reported that the FA content in the leaching water do not contribute to any fungicidal effect and combustion of furfurylated wood releases little volatile organic compounds or polyaromatic hydrocarbons (Lande et al. 2004a;Pilgard et al. 2010), namely, furfurylated wood has very low negative environmental impact with respect to the usage and disposal. ...
Article
Plantation-grown poplar ( Populus cathayana ) is regarded as a source of low-quality wood, with poor dimensional stability and low decay resistance. In this study, poplar wood was impregnated with sodium montmorillonite (Na-MMT) or organo-montmorillonite (O-MMT), furfuryl alcohol (FA, at concentrations of 15%, 30% and 50%), separately or in their combinations to prepare clay treated, furfurylated, and clay-reinforced furfurylated wood, respectively. The two-step method by introducing Na-MMT first and then FA and organic modifier was feasible to achieve a reasonable penetration. These components could entirely enter the wood cell lumen or partly enter the wood cell wall, and thus initiate a series of reactions. Compared with Na-MMT reinforced furfurylated wood (M-F), the O-MMT reinforced furfurylated wood (O-F) exhibited better dimensional stability (ASE up to 71%) and decay resistance (3.2% mass loss). Moreover, O-MMT played a predominant role in decay resistance of O-MMT reinforced furfurylated wood. Even at low O-MMT loadings, the modified wood had a significant inhibitory effect on the white-rot decay fungus Trametes versicolor . Based on an overall evaluation, O-MMT reinforced furfurylated wood seemed to provide an optimal choice for both moist or wet conditions.
... Whilst wood is a sustainable biopolymer that has been used in various applications such as construction or furniture, its intrinsic hydrophilicity, low to medium durability and low fire stability limits its application in our modern society. Bio-derived furfuryl alcohol (FA) has been shown as a means for improving the durability of wood (Baysal et al. 2004, Lande et al. 2008, since FA readily penetrates the wood cell wall and reinforces the wood cell with the polymerised hydrophobic FA (Kong et al. 2018). Nevertheless, the fire stability of the furfurylated wood is considered the same level as the unmodified wood (Dong et al. 2015). ...
Article
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Furfurylated wood has been used widely for exterior purposes due to its superior dimensional stability and biological durability, though its fire resistance is not enhanced. Here, the introduction of the fire-retardant additive guanyl-urea phosphate (GUP) into furfurylated wood is reported. The treatment improved both the thermal and fire stabilities of the modified wood, as supported by the results of thermal gravimetric analysis (TGA) and limiting oxygen index (LOI) before and after accelerated ageing testing (according to EN 84) to determine the water resistance of the treatment. The results indicated that the hydroscopic GUP remained within the wood structure and provided superior thermal and fire properties. The work suggests the idea of combining GUP and furfuryl alcohol (FA), which has the prospective to impart substantial fire-retardancy to the furfurylated wood, thus increasing the potential for exterior applications.
... In recent years, bio-based and biodegradable polymers have been considered for replacement of fossil-based polymers in loadbearing biocomposites. Furfuryl alcohol is a bio-based resin used as a substitute for phenol formaldehyde resins (Lande et al., 2008), although the black color and toxicity (monomer and catalysts) are problematic. Other bio-based polymers considered for plant fiber composites include thermosets based on vegetable oils (Williams and Wool, 2000;O'Donnell et al., 2004). ...
Article
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The development of large, multifunctional structures from sustainable wood nanomaterials is challenging. The need to improve mechanical performance, reduce moisture sensitivity, and add new functionalities, provides motivation for nanostructural tailoring. Although existing wood composites are commercially successful, materials development has not targeted nano-structural control of the wood cell wall, which could extend the property range. For sustainable development, non-toxic reactants, green chemistry and processing, lowered cumulative energy requirements, and lowered CO2-emissions are important targets. Here, modified wood substrates in the form of veneer are suggested as nanomaterial components for large, load-bearing structures. Examples include polymerization of bio-based monomers inside the cell wall, green chemistry wood modification, and addition of functional inorganic nanoparticles inside the cell wall. The perspective aims to describe bio-based polymers and green processing concepts for this purpose, along with wood nanoscience challenges.
... Superior improvements in dimensional stability, biological durability and mechanical properties were recognized after chemical wood modifications e.g. by the treatment with acetic anhydride (Larsson Brelid et al. 2000, Westin et al. 2006, 2016, Rowell 2014 or furfuryl alcohol (Lande et al. 2008, Li et al. 2015, Westin et al. 2016. Permanent property improvements were also observed when various "curing resins" such as melamine formaldehyde (MF) (Altun and Tokdemir 2016), phenol formaldehyde (PF) (Bicke 2019) and 1,3dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) ) had been used for wood modification. ...
Article
Novel approaches for a non-toxic protection of timber have been investigated and referred to as “wood modification”. Especially, chemical impregnation modifications show promising opportunities to improve a wide range of wood properties. Yet, most of the available treatments resort to technically synthesized oil-based chemicals. Therefore, new ways of wood modification based on citric acid (CA) and bio-based low-molecular-weight polyols (CA-PO) – both originating from renewable resources – are under test and appear to be a promising alternative to available processes. The mode of action is expected to be a combination of both a cell wall bulking, and a cross-linking between CA-PO polyesters and wood cell wall polymers. However, the treatment process requires optimization with regard to the impregnation system and parameters for an industrial scale implementation. This paper provides a general background about CA-based solid wood treatment and its effects on the characteristics of wood. Moreover, it discusses current developments in this area and points out existing research gaps, with one focus being the process of development on an industrial scale.
... However, zinc chloride easily separates from FA during penetration, with devastating effects on cellulose degradation and the long-term strength properties of treated wood (Anaya 1987). Schneider (1995) and Westin (1995) simultaneously developed alternative efficient catalysts using cyclic carboxylic for furfurylation of wood, citric acid, and maleic anhydride, which are the most studied catalysts in wood furfurylation (Lande et al. 2004(Lande et al. , 2008Venas and Rinnan 2008;Thygesen et al. 2010;Pfriem et al. 2012). Additionally, Baysal et al. (2004) reported that borates could be used as catalyst to perform furfurylation to improve the dimensional stabilization of wood. ...
Article
In this study, 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) and furfuryl alcohol (FA) modification catalyzed by acrylic acid were comparatively studied. The effects on physical-mechanical properties and durability against mould of Masson pine and Camphor pine wood were investigated, including weight gain rate (WPG), moisture uptake, equilibrium moisture content (EMC), anti-swelling efficiency (ASE), parallel-to-grain compressive strength (CS), modulus of rupture (MOR), and mould resistance. The wood samples modified with DMDHEU closely retained their original color and texture, whereas the color of furfurylated wood became dark brown and the texture became clearer. The WPG of DMDHEU-treated wood ranged from 17.9% to 29.3%, which was lower than that of furfurylated wood that ranged from 36.7% to 39.3%. The equilibrium moisture content of DMDHEU-modified wood was slightly higher than the untreated wood, while furfurylation decreased the EMC of wood by approximately 50% compared with the untreated wood. The dimensional stability, parallel-to-grain compressive strength, and mildew resistance of Masson pine and Camphor pine improved after both modifications noticeably. It was concluded that acrylic acid can be utilized as a catalyst to perform wood furfurylation and DMDHEU modification.
... Construction materials (Lande et al., 2008) Step 1: The treating solutions are mixed in a mixing tank that consists of furfuryl alcohol, inhibitor, buffering agents, surfactants, and water before the solution is pumped into the buffer tanks. ...
Article
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Australia has significant wood resources in its native forest, but the resource available for harvest becomes lesser due to the conversion of native forest to conservation reserves. The natural occurrences of bushfires, droughts, and cyclones are highly destructive, making the situation worse. The shortage of wood resources is having a significant negative impact on Australia because wood is so scarce that they cannot meet domestic demands, especially durable wood. Australia cleared approximately 100 million hectares of its land to establish forest plantations, and two million trees were planted. However, most of these plantations are for pulpwood production; however, their application for high-value products is limited due to their undesirable properties. Wood modification is a process of improving unfavorable wood properties to be utilized for a wide range of applications. Australia has not adopted any of these modification processes; it still depends on the less toxic wood preservative to treat wood. This study focuses on the recent advancement in industrial wood modification worldwide and how it may be used to modify Eucalyptus wood for high-value applications. The opportunities and suggestions for Eucalyptus wood modification in Australia will be discussed. Before the study concludes, the future of commercial wood modification for Eucalyptus plantation in Australia will also be presented.
... Catalyst plays an important role in wood furfurylation, ensuring long pot-life and rapid polymerization when heated. FA can be polymerized by many acidic catalysts, such as maleic anhydride and citric acid (Hill et al. 2006;Lande et al. 2008;Pfriem et al. 2012;Thygesen et al. 2010;Venås and Rinnan 2008). Furthermore, catalysts should have low molecular weight and similar affinities to wood substances and FA to ensure deep penetration into wood with FA. ...
Article
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In order to improve dimensional stability and durability of wood, furfurylation of poplar and Chinese fir wood using newly developed furfuryl alcohol (FA) formulation combined with a common vacuum and pressure impregnation process was studied. An orthogonal experiment was designed to optimize the furfurylation process for the two wood species. The weight percent gain (WPG), equilibrium moisture content (EMC), anti-swelling efficiency (ASE), modulus of rupture (MOR), modulus of elasticity (MOE), as well as resistance to mold, decay fungi, and termites were evaluated. The results showed that nearly all the properties of the furfurylated wood could be improved to various extents. The average ASE of the furfurylated Chinese fir and poplar could reach as high as 80, 71, 92% and 79, 90, 75% in tangential and radial directions, and by volume, respectively, higher than most previously reported wood modification processes. Furthermore, the modified wood had excellent biological durability, with nearly 100% mold resistance, strong decay and termite resistance. Finally, processing parameters with 50% FA, 105–115 °C curing temperature, and 5–8 h curing time were therefore recommended for pilot-scale production of furfurylated poplar and Chinese fir wood based on range analysis.
... It is known that furfurylation greatly improves dimensional stability, hardness, and biodegradation resistance of wood and bamboo (Lande et al. 2008, Esteves et al. 2011, Dong et al. 2015, Wang et al. 2019, Thygesen et al. 2020. Less is known about the effects of furfurylation on the resistance of wood and bamboo to weathering. ...
Article
Although furfurylation greatly improves dimensional stability, hardness, and biodegradation resistance of wood and bamboo, the effects of furfurylation on the resistance of wood and bamboo to weathering are still not clear. In this study, poplar wood and moso bamboo were furfurylated and underwent artificial weathering. The surface chemical changes of the control and furfurylated wood and bamboo samples were examined using the attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The colour changes were also investigated by measuring CIELab parameters. Results demonstrated that the wood/bamboo surfaces showed decreased lightness and became reddish and yellowish after artificial weathering. Furfurylation endowed poplar wood and bamboo with improved stability of photo-discolouration. Weathering caused remarkable degradation of lignin in the control and furfurylated sample surfaces with decreased aromatic carbons and increased oxygenated carbons. The poly(furfuryl alcohol) in sample surfaces could also be oxidized during weathering. Compared with the furfurylated bamboo, the furfurylated poplar wood had higher stability of photo-degradation.
... Furfurylated wood had better dimensional stability and mechanical properties, and was more resistant to organism attack. Modification of wood with furfurylation shows better results and less impact on the environment, so this process was in high demand, especially in Europe [8]. ...
Article
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Wood from plantation forest contains a lot of sapwood and juvenile wood which has inferior in physical properties. Furfurylation could improve the properties through a reaction between Furfuryl Alcohol (FA) with a hydroxyl group of wood components. The purpose of the study was to improve the physical properties of mangium ( Acacia mangium Willd.) and pine ( Pinus merkusii Jungh et de Vriese) woods. The wood specimens for physical properties was prepared according to the ASTM D 143-94. They were vacuumed at 600 mmHg during 30 minutes, when the vacuum has been released, the FA reagent was inserted to the tank and followed with pressure at 10 kg/cm ² during 30 minutes. The specimens were wrapped with aluminium foil and heated in the oven at 100°C for 24 hours. After conditioned for three weeks, the specimens were tested for physical properties including Weight Percent Gain (WPG), density, Moisture Content (MC), water absorption, swelling, shrinkage, and anti-swelling efficiency (ASwE) according to the ASTM D 143-94. Untreated specimens were also prepared for comparison purpose with five replications for each treatment. The results showed that furfurylated mangium and pine woods reached WPG 11.34% and 17.74%, densities were increased 8.95% and 3.75%, MC were decreased 88.41% and 84.74%, water absorption were decreased 41.76% and 46.84%, volume swelling were decreased 55.18% and 61.57%, volume shrinkage were decreased 34.99% and 64.75%, respectively. ASwE of mangium and pine woods was 55.1% and 61.6%. It could be mentioned that the furfurylated wood had better physical properties compared to untreated woods.
... These results align with those determined in past studies [22][23][24]. Furfurylation involves a chemical reaction with wood through cross-linkages or even penetration into the wood cell wall, thus changing the wood cell wall [25][26][27]. These changes apparently allow furfurylated jabon wood to become more resistant to termite attack than untreated wood but are not for the other wood species. ...
Article
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In general fast-growing tree species harvested at a young age has substantial amount of sapwood. It also contains juvenile wood, which has undesirable inferior physical and mechanical properties. Having sapwood and juvenile wood in the trees makes them very susceptible to be attacked by biological deterioration specifically termites in a tropical environment. The main objective of this study was to investigate the termite resistance of four fast-growing Indonesian wood species treated with furfuryl alcohol and imidacloprid. Wood specimens from sengon (Falcataria moluccana), jabon (Anthocephalus cadamba), mangium (Acacia mangium), and pine (Pinus merkusii) were impregnated with furfuryl alcohol, using tartaric acid and heat as well as treated with imidacloprid for the polymerization process. All of the specimens were exposed to environmental conditions in the field for three months. Based on the findings in this work, the untreated control samples had higher weight loss values and lower protection levels than those of imidacloprid-treated and furfurylated samples of all four species. It appears that furfurylation and imidacloprid treatment of such fast-growing species had a significant impact regarding their resistance against termite so that their service life can be extended during their utilization.
... -For wood industry, for reinforcement 123,124 or adhesives 125,126 -As binders 127 , for several applications such as porous materials for methane storage 128 -For corrosion and fire-resistant materials 108,129,130 -For sand consolidation for foundry molds 131,132 . ...
Thesis
To reduce the use of finite petroleum-based resources, interest has grown regarding the valorization of renewable resources in chemistry. The work presented in this thesis focused on two bio-based resources: plant oil and lignocellulosic biomass, for the preparation of greener thermoset materials. The first part discussed about polybenzoxazine thermosets. The bio-based content was gradually increased through substitution of petro-based phenol by bio-based cardanol. Cardanol is a natural phenolic derivative extracted from the cashew nutshell liquid. A first study focused on the effect of this aliphatic side chain and how it can tune the reactivity and the final thermo-mechanical properties of the materials. In the following study the reactivity of polymerization of di-phenol monomer was investigated using advanced isoconversional analyses and thermo-mechanical analyses for a better understanding of the polymerization reaction. The second part discussed about the preparation of fully bio-based composites using modified cellulose microfibrils (MFC). Poly(furfuryl alcohol) (PFA) is a bio-based matrix obtained after polymerization of furfruyl alcohol (FA) with maleic anhydride, both obtained from HMF. The PFA properties can be modified by the introduction of cellulose as a filler. MFC was modified by oxidation to lead to reactive dialdehyde functions. By varying the degree of oxidation (DO), the properties of different composites were studied to determine the most adequate DO for the better PFA/MFC compatibility and the most adequate PFA/MFC ratio. Finally, the last study of this thesis focused on the concept of “all cellulose composites” (ACC), and particularly how to reduce the moisture sensitivity of these materials. Two different furanic compounds were used as cross-linkers to increase the hydrophobicity: a first compound with one furan ring and a second with two furan rings.
Chapter
This chapter presents the technology of chemical and thermal wood modification. It describes fundamental principles as well as practical aspects of wood modification. In addition to thermal modifications, various types of chemical modifications are presented with respect to the chemicals applied and resulting properties of the modified wood. This does not only include results from the laboratory and pilot plant scale but also industrial processes and their commercial products.KeywordsChemical modificationThermal modificationDimensional stabilizationDecay resistanceFurfurylationEsterificationAcetylationEtherificationGraftingCommercialization
Article
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To upgrade the hydrophobicity, dimensional stability and mechanical properties of planted fast-growing poplar wood (Populus cathayana Rehd.), we proposed to fabricate wood-polymer composites (WDPF) by introducing biomass-derived furfuryl alcohol (FA) and polyvinyl alcohol (PVA) into wood cells after delignification. The results showed that delignification enhanced wood porosity and benefited polymer impregnation and uniform distribution in cell walls, causing higher cell wall bulking. Hydrophobic FA and PVA blocked water paths and formed films on cell surface, reducing water accommodation and hindering wood-water interaction. Consequently, the hydrophobicity and dimensional stability were highly enhanced, as indicated by the moisture content and volume change decrease by over 46% and steady high contact angle. WDPF had improved flexural strength and modulus of elasticity by over 21% and 46% respectively. Besides, the impact toughness of WDPF increased by over 90% compared to furfurylated wood. The mechanical property improvement was mainly ascribed to the combined effects of PVA-FA interaction and delignification. PVA with flexible macromolecular chains interacted with FA and wood, interrupting FA crosslinking and forming polymer networks in hierarchical structures of wood. Additionally, delignification and PVA facilitated orderly arrangement of micro-fibrils and increased crystallinity and mechanical strength. The fabrication and mechanism analysis of WDPF can be used as a reference for upgrading low-quality wood products. Graphical abstract
Article
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Bagasse is a waste product from the sugar industry, which is usually used as energy source in factory at present. However, the amount of bagasse left is still high enough for more value-added product for example furfural. Bagasse is a good source of pentosan and containing about 25 to 27%. The main objective of the research was to produce furfural from bagasse. The main raw material for the production furfural was bagasse and some chemicals/ingredients were used (H 2 SO 4 , water, NaCl). Furfural is an important organic chemical, produced from agro industrial wastes and residues containing carbohydrates known as Pentosans. It is a basic chemical, which can be utilized in a variety of industries such as chemical industry, refining oil industry, food industry and agricultural industry. In its pure state, it is a colourless or yellow oily liquid with the odour of almonds, but upon exposure to air it quickly becomes yellow then brown and finally black, it is commonly known as furfuraldehyde.
Article
Inorganic borates are effective against the attacks from wood decay fungi and termites; however, they are inclined to leach out during outdoor service. In order to improve boron leaching resistance, and enhance the overall performance of wood, including the resistance against decay fungi and termites, dimensional stability, and alleviate the toughness loss caused by furfurylation, a ternary-treatment system composed of disodium octaborate tetrahydrate (DOT), furfuryl alcohol (FA) and polyvinyl alcohol (PVA) is proposed and impregnate wood in a two-step process in this study. Results of boron analysis by the inductively coupled plasma-atomic emission spectroscopy (ICP-AES) show that the leaching rate of boron of DOT/FA/PVA treated wood is intensively slowed down, especially during the initial period. Decay resistance of DOT/FA/PVA treated wood against both white rot fungi Coriolus versicolor and brown rot fungi Gloeophyllum trabeum still shows promising results after leaching tests, respectively 1.33% and 1.71%. Compared with DOT-treated wood, the combinations with FA can provide better protection against termites and greatly improve dimensional stability, but PVA shows a little negative effect on termite resistance. Nevertheless, PVA can alleviate the reduction of impact toughness due to furfurylation to a certain extent. In summarization, the combination system of DOT/FA/PVA should be a promising protection approach for wood used for outdoor applications.
Preprint
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Short rotation teak from plantation has been around 30 cm in diameter at the age of 15 years, however the wood is low quality especially in dimensional stability and durability. The short rotation teak wood was treated by non-biocide chemicals of Citric Acid (CA) and Benzophenone Tetracarboxylic Acid (BPTCA). The objective of this study was to improve dimensional stability and durability of the short rotation teak by modification treatment of Citric Acid and Benzophenone Tetracarboxylic Acid. Short rotation teak sapwood was impregnated by 20% and 40% of both CA and BPTCA followed by heated in oven at 150 °C (HT150 o C) for 2 h. Dimensional stability was characterized by anti-swelling efficiency (ASE), water uptake (WU), and termite durability was determined by weight loss (WL) and percentage of damage of the wood samples. The results show that the ASE values increased in the average of 46% and 50% after CA and BPTCA treatments, respectively. The WU values decreased in the average of 34% and 22% after CA and BPTCA treatments, respectively. These phenomena indicated a remarkable improvement in dimensional stability of the treated teak wood. Weight losses of treated teak woods due to termites were in the average of 1.0% and 1.5% after CA and BPTCA treatments, respectively, which categorized their durability to be class 1 (very durable). The results showed by Fourier Transform Infrared (FTIR) indicate that chemical reaction of wood lignin with CA and BPTCA chemicals was occurred. The non-biocide CA and BPTCA treatment can be applied for improving the quality of short rotation teaks for high quality wood product utilization.
Conference Paper
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Furfurylated wood has been used widely for exterior purposes due to its superior dimensional stability and biological durability, though its fire resistance is not enhanced. Here, Scots pine (Pinus sylvestris L.) sapwood was impregnated with a hygroscopic fire-retardant guanyl-urea phosphate (GUP) and furfuryl alcohol (FA) by a vacuum-pressure impregnation followed by curing in elevated temperature. The water-resistance of such treated material was evaluated according to European standard EN 84. Scanning electron microscopy coupled with energy�dispersive X-ray spectroscopy (SEM-EDX) revealed the penetration of GUP into the cell wall. The hydrophobic FA polymerised in-situ within the wood structure, and this enhanced the water-resistance of GUP. Fourier-transform infrared spectroscopy (FTIR) showed that the chemical functionalities changed such as formation of methylene bridges attributed to the polymerised FA and ketone groups attributed to GUP. Thermal gravimetric analysis (TGA) showed that GUP enhanced thermal stability at elevated temperature by promoting char formation. Fire stability test examined by limiting oxygen index (LOI) showed the improvement of fire-retardancy by the incorporation of GUP. Mechanical properties examined by Brinell hardness and three-point bending test indicated that GUP has a low impact on the properties of surface hardness, modulus of elasticity (MOE) and modulus of rupture (MOR) of the furfurylated wood. The work suggests that GUP/FA treatment has the prospective to impart substantial fire-retardancy to the furfurylated wood with small reduction in other properties, thus increasing the potential for exterior applications.
Chapter
Polymer networks derived from furan monomers are discussed, with particular emphasis on recent contributions. Resins based on furfural and furfuryl alcohol represent the most important family within this context, but other materials are becoming relevant, such as polyurethane foams, various photocurable macromolecules bearing furan rings within the chain, or pendant to it, conjugated cross-linked poly(2-vinylfuran) as proton traps, and thermoreversible networks prepared by Diels–Alder polycondensations involving furan and maleimide moieties.
Article
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The improvement of durability and dimensional stability of wood properties via modification of the microstructure and wood–water interaction has been widely utilised. This study investigated polyester treatments, a possible alternative, using environmentally friendly chemicals such as malic acid to improve the beech wood ( Fagus sylvatica ) properties. The modified properties have been studied with four treatments using malic acid, glycerol, butanediol and succinic anhydride, mixing polycarboxylic acids and polyols. Results showed that the anti-swelling-efficiency (ASE) improved up to 70%, and the bulking coefficient improved around 23%, exhibiting an efficient penetration within the cell walls. The leaching rates (LR) of treatments and the extractables remained low, between 0.05 and 2.4%. The equilibrium moisture content (EMC) decreased by 50% for the four treatments, compared to untreated beech wood.
Article
Furfural (F) cannot be easily polymerized like furfuryl alcohol, but it is an aldehyde that can react with urea (U) to make a polymeric network. The possibility of preparing F/U polymer along with an acidic catalyzer (maleic anhydride; M) was evaluated as a means to improve some selected properties of birch (Betula pendula) wood. The F+U/M resin was introduced into the wood with a double treatment technology. The first step involved dilution of F in water and methanol, and the second step was immersion in a U/M aqueous solution. The color of treated wood was darkened after resin curing from brown to a spectrum of black depending on the amount of loaded resin. The 60 to 80% of materials were converted to a non-leachable polymer based on the different formulations. The water absorption and volumetric swelling of the treated samples decreased with an increase in weight percent gain (WPG). The analysis of mechanical strength showed that treatment with F + U/M reduced to some extent the hardness and the impact bending of wood, while modulus of rupture, modulus of elasticity, and compression parallel to the grain with WPG were increased. The exposure of the samples to the accelerated weathering showed noticeable changes in color and roughness.
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Wood has played a major role throughout human history. Strong and versatile, the earliest humans used wood to make shelters, cook food, construct tools, build boats, and make weapons. Recently, scientists, politicians, and economists have renewed their interest in wood because of its unique properties, aesthetics, availability, abundance, and perhaps most important of all, its renewability. However, wood will not reach its highest use potential until we fully describe it, understand the mechanisms that control its performance properties, and, finally, are able to manipulate those properties to give us the desired performance we seek. The Handbook of Wood Chemistry and Wood Composites analyzes the chemical composition and physical properties of wood cellulose and its response to natural processes of degradation. It describes safe and effective chemical modifications to strengthen wood against biological, chemical, and mechanical degradation without using toxic, leachable, or corrosive chemicals. Expert researchers provide insightful analyses of the types of chemical modifications applied to polymer cell walls in wood. They emphasize the mechanisms of reaction involved and resulting changes in performance properties including modifications that increase water repellency, fire retardancy, and resistance to ultraviolet light, heat, moisture, mold, and other biological organisms. The text also explores modifications that increase mechanical strength, such as lumen fill, monomer polymer penetration, and plasticization. The Handbook of Wood Chemistry and Wood Composites concludes with the latest applications, such as adhesives, geotextiles, and sorbents, and future trends in the use of wood-based composites in terms of sustainable agriculture, biodegradability and recycling, and economics. Incorporating decades of teaching experience, the editor of this handbook is well-attuned to educational demands as well as industry standards and research trends.
Article
The dimensional instability and inferior mechanical strength of radiata pine ( Pinus radiata D. Don) limit its use in musical instruments. To improve its properties, a two-step treatment by furfuryl alcohol (FA) and tung oil (TO) were used involving impregnation of FA precursor solution into the wood matrix, forming a highly cross-linked resin, followed by a modification with TO. Examination using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy revealed that FA resin was attached in cell walls and lumens, and the solidified TO in cell lumens and occluded pits. The incorporation of FA resin reduced the wood swelling coefficient by over 70% and the hydrophobic solidified TO decreased wood water uptake by over 80% enhancing wood dimensional stability. Although FA resin improved the modulus of elasticity and hardness of the wood, the modulus of rupture and impact bending strength were reduced. However, the additional TO impregnation step improved the modulus of rupture, impact bending strength, and wear resistance of the furfurylated wood. The performance of FA and TO treated radiata pine wood was better than that treated with FA or TO alone, and could meet the performance requirements of wood used for fretboard of string instruments.
Article
Wood and wood-based products have the problem of dimensional instability caused by changes in moisture content. Furfurylation modification is an environmentally-friendly approach for wood stabilization. However, it normally adopts traditional liquid phase vacuum and pressure impregnation (VPI) process, which has the inherent shortcomings of huge modifier consumption, wood drying defects after impregnation, and troublesome disposal of waste liquor. In this study, a novel process, vapor phase furfurylation (VPF), was for the first time applied to wood, leading to super-stable wood material (ASE > 80%) with low furfuryl alcohol (FA) resin loading (weight percentage gain < 15%). This process totally avoids invalid deposition of FA resin in the cell cavities of modified wood and meanwhile ensures the furfurylation of wood cell walls, as demonstrated by scanning electron microscopy (SEM) and nanoindentation. Furthermore, the distribution of FA resin in wood with VPF process was evaluated with dynamic vapor sorption (DVS) and imaging FT-IR. Our study demonstrated a VPF process that has the potential to produce functionally gradient furfurylated wood with high dimensional stability at low production cost. Furthermore, VPF at 115 ℃ for a duration of 40 h with a maleic anhydride (MA) concentration of 4.5% was proposed as an optimized process based on orthogonal experimental design and range analysis.
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Le hêtre est une essence très répandue sur le territoire français et plus particulièrement dans la région Grand-Est. Toutefois, son bois est peu exploité, notamment pour des utilisations en conditions extérieures en raison de sa faible durabilité et son instabilité dimensionnelle. Pour favoriser et développer son utilisation, il est nécessaire de le traiter afin de limiter sa reprise en humidité et de le protéger contre les champignons de pourriture. Par ailleurs, la réglementation actuelle sur les produits de traitement du bois impose la mise au point de solutions alternatives respectueuses de l’environnement et de la santé. Dans ce cadre, les travaux développés durant cette thèse visent la valorisation du hêtre en tant que matériau via sa protection par un traitement « non-biocide », la furfurylation. Cette méthode consiste à polymériser in situ de l’alcool furfurylique dans le bois de hêtre. La mise au point du procédé a permis d’aboutir à du hêtre composite dont la durabilité et la stabilité dimensionnelle sont nettement améliorées. D’autre part, le hêtre est une essence feuillue pour laquelle la fraction hémicellulosique est riche en pentoses et plus précisément en xylose, précurseur de furfural. Des travaux ont donc été menés pour produire du furfural par hydrodistillation acide à partir de connexes issus de l’industrie de la première transformation du hêtre. Le furfural a ensuite été réduit en alcool furfurylique par transfert d’hydrogène. Les résultats prometteurs obtenus montrent qu’il est possible de mettre en place une filière locale alliant le hêtre comme source de molécules furaniques et le bois de hêtre comme matériau
Article
Two-step treatment involving partial hemicellulose removal and furfurylation was proposed to improve the dynamic dimensional stability of fast growing poplar wood (Populus euramericana Cv.). Moisture content (MC) and dimensional changes were automatically measured during cyclic process where relative humidity changed sinusoidally from 45% to 75% at 25°C. Hemicelluloses were partially removed and furfural resin chemically in situ polymerized in wood from both results of Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Hemicellulose removal caused many voids in cell walls, and partial furfural resin polymerized in these voids suggested by the results of scanning electron microscope (SEM) and confocal laser scanning microscopy (CLSM). The distribution of modifier was more uniform and the cell wall bulking was more obvious for the furfurylated wood with low hemicellulose content (LHF). After the two-step treatment, MC and dimensional changes were presented as similar sinusoidal shapes to RH. The average MC was reduced by over 50% and tangential dimensional change decreased by over 40%. MC and dimensional amplitudes both fell with the most scope above 50%. Moisture sorption coefficient and humidity expansion coefficient dropped by more than 50% and 30% respectively. The two-step treatment could reduce the hygroscopicity and improve the dimensional stability greatly by varying the physical-chemical environment for water in modified wood. Chemically, the effective hydroxyl groups decreased after hemicellulose removal. Physically, furfural resins blocked water exchange paths and reduced the space to accommodate water or covered the adsorbed sites as a resin film and caused permanent bulking of cell wall.
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Furfuryl alcohol was polymerized by trifluoroacetic acid in methylene chloride to give a colored polymer. This polymer possesses two main sequences in which the furan rings are connected by methylene groups (sequence 1) or by dimethylene ether groups (sequence 2). The polymer is not linear but highly branched, as detected by 1H and 13C NMR spectroscopy. Variations of the experimental conditions, such as the presence of air, the trifluoroacetic acid concentration, the reaction temperature and the solvent, do not allow a significant increase in the linear structure of the polymer. However, an increase in the acid concentration or an increase in temperature produce a decrease in the ether-bridged structure (sequences 2).
Article
White fir wood flour, microcrystalline cellulose, milled-wood lignin, and ammonium lignosulfonate were mixed with furfuryl alcohol and maleic acid in various proportions in presence or in asence of hydrogen peroxide. Interactions of the above materials were analyzed using differential scanning calorimetry and infra-red spectroscopy. Hydrogen peroxide reacted exothermally with wood flour, cellulose, lignins, and furfuryl alcohol and modified their chemical functionality. Furfuryl alcohol in presence of just maleic acid homopolymerized and copolymerized exothermally with the lignin materials; polymerization and copolymerization of furfuryl alcohol proceeded differently in presence of hydrogen peroxide or of hydrogen peroxide-reacted lignins or of hydrogen peroxide reacted wood. A graft copolymerization appears to take place between hydrogen peroxide-reacted wood, furfuryl alcohol, and ammonium lignosulfonate.
Article
The first processes of wood modification with furfuryl alcohol (FA) (furfurylation) were developed several decades ago. FA is a renewable chemical, produced from hydrolysed biomass waste. Over the past decade modernized processes for furfurylation of wood have been developed. This study presents decay properties of furfurylated wood. Laboratory methods and field tests were performed on fungi, termite and marine borer attack. Tests on physical and mechanical properties are also presented. The properties of furfurylated wood depend on the retention of grafted/polymerized poly-FA in the wood. At high modification levels (high retention of poly-FA) the enhancement of a wide variety of properties is achieved: an exceptional increase in hardness, exceptional resistance to microbial decay and insect attack, increase in modulus of rupture (MOR) and modulus of elasticity, and high dimensional stability. At lower modification levels property enhancements also occur. Notable are resistance to microbial decay and insect attack, and relatively high dimensional stability.
Article
Over the past decade modernized processes for furfurylation of wood have been developed. These new processes are based on completely new catalytic systems and process additives. These new systems do not add metals or halogens to the product, which is important for an environmentally acceptable product. However, little is known about the ecotoxicity of furfurylated wood or other environmental impacts that may result from the modification method. The study shows that concentrations of non-reacted furfuryl alcohol in the final products are low and do not contribute to any fungicidal effect. Environmental tests show no significant level of increased ecotoxicity, and degradation through combustion does not release any volatile organic compounds or polyaromatic hydrocarbons above normal levels for wood combustion. Hence, furfurylation of wood to enhance wood properties is not believed to be harmful to the environment.
Article
Reaction products of phloroglucinol or catechin with furfuryl alcohol and furfuraldehyde were studied. In reactions of furfuryl alcohol with phloroglucinol, only 2-furyl-1′,3′,5′-trihydroxyphenyl) methane was obtained as product, and 53% of the phloroglucinol was recovered. Reactions of furfuryl alcohol with catechin gave 2-furyl-(8-catechinyl) methane and 2-furyl-(6-catechinyl) methane in 4.0% and 1.5% yields, respectively, while 62% of the catechin was unreacted. Polymeric furans with few catechin moieties made up the oligomeric products (38% of catechin). Reaction of phloroglucinol with furfuraldehyde gave 2-furyl-di(1′,3′,5′-trihydroxyphenyl) methane, an unstable product that readily polymerized during isolation. The solid state C-NMR spectrum of the higher polymers suggested one phloroglucinol moiety per furan unit, but lower oligomers contained more furan-furan condensation products. Reactions of catechin with furfuraldehyde gave 2-furyl-di(8-cate-chinyl) methane and the two diastereomers of 2-furyl-(6-catechinyl)-(8-catechinyl) methane in low yield, with 65% of the catechin unreacted.
Article
A thorough investigation of the acid-catalyzed polycondensation of furfuryl alcohol was conducted with the specific aim of understanding the mechanisms responsible for the main reaction, but more particularly for the transformation of linear unconjugated oligomers into black cross-linked final materials. The originality of the present approach, compared with previous unsuccessful attempts, consisted in calling upon numerous model compounds simulating specific features of both the monomer and its condensation products. The formation of conjugated sequences along the poly(furfuryl) chains is caused by repetitive cycles involving the loss of hydride ions followed by the deprotonation of the carbenium ions thus formed. This reaction was simulated and accelerated by using cationic hydride-ion abstractors. The branching reactions only occur after the appearance of the multiple unsaturations and owe their origin to interchain cycloadditions between furan rings and conjugated structures. A long-standing puzzle has thus been solved.