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Handbook Of Wood Chemistry And Wood Composites
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The degradable nature of high-performance, wood-based materials is an attractive advantage when considering environmental factors such as sustainability, recycling, and energy/resource conservation. The Handbook of Wood Chemistry and Wood Composites provides an excellent guide to the latest concepts and technologies in wood chemistry and bio-based composites. The book 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, emphasizing the mechanisms of reaction involved and resulting changes in performance properties. These include modifications that increase water repellency, fire retardancy, and resistance to ultraviolet
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... The cross section of wood reveals details about the features from the pith to the bark in the radial and tangential directions. The subdivisions of wood include the pith, heartwood, sapwood, vascular cambium, and bark [1]. ...
... The wood cell wall has two main parts: the primary cell wall, which allows for cell expansion, and the subsequent secondary cell walls (S1, S2, and S3), which significantly influence the properties of the cell and wood [2]. Lignin content is highest in the primary wall and middle lamella, decreasing toward the lumen in the secondary walls [1]. The thickest part of the cell wall, the S2 layer, significantly influences the overall properties of the wood [3]. ...
... It is primarily composed of polysaccharides (65-75%) and lignin (18-35%). The chemical composition varies among wood species, with differences in cellulose, lignin, and pentosan content [1]. Cellulose is a linear homopolymer with high molecular weight. ...
Wood stands as a cornerstone of renewable resources, offering sustainability and versatility. Today, its potential is exponentially broadened by creative integration with polymers and resins. This chapter delves into groundbreaking research, starting with a brief wood’s intrinsic structure and advancing through commercial wood modification technologies (thermal treatment, chemical modification, and impregnation modification), their characteristics, and industrial perspectives. Furthermore, the chapter introduces advanced modifications of wood structures, focusing on more efficient, scalable, and energy-saving top-down technologies. These innovations will highlight the development of wood composites with futuristic functionalities and diverse applications, such as phase-change energy storage, hydrogels, and transparent wood composites.
... Lignin contents were determined following TAPPI um 250 (acid soluble) [26] and TAPPI T222 om-02 (acid insoluble) [27] methods. Holocellulose and αcellulose contents were determined according to Wise et al. [28] and Rowell [29], respectively. Hemicelluloses were calculated by the difference in holocellulose and α-cellulose contents. ...
... Lignin contents were determined following TAPPI um 250 (acid soluble) [26] and TAPPI T222 om-02 (acid insoluble) [27] methods. Holocellulose and α-cellulose contents were determined according to Wise et al. [28] and Rowell [29], respectively. Hemicelluloses were calculated by the difference in holocellulose and α-cellulose contents. ...
Rugulopteryx okamurae (RO) is a species of brown seaweed that has invaded several shorelines worldwide, including the Spanish Mediterranean and the Strait of Gibraltar coasts, causing serious environmental and economic problems. This work aimed to characterize the bioactive composition of RO. A high content of carbohydrates (58.7 ± 2.6 wt%), fats (17.1 ± 0.4 wt%), and ashes (14.3 ± 0.2 wt%) were found, together with lower protein content (5.5 ± 1.8 wt%). Holocellulose was the most abundant polysaccharide fraction (49.2 ± 1.3 wt%), showing 43.4 ± 2.0 wt% of cellulose and 5.8 ± 0.7 wt% of hemicellulose, followed by lignin (18.9 ± 2.5 wt%). The monosaccharides composition showed a high level of glucose (13.2 ± 1 wt%) and glucuronic acid (9.3 ± 0.5 wt%). RO contained high levels of essential nutrients (Ca, K, Na, S, Mg), trace minerals (Mn, Mo, Se, and Cu), and some toxic heavy metals (Ni, Cd, As). The main fatty acid present in RO was palmitic acid (C16:0, 30.8 ± 3.0 mg/100 g), followed by myristic acid (C14:0, 19.3 ± 2.4 mg/100 g) and eicosatetraenoic acid (C20:4, 19.2 ± 1.3 mg/100 g). The extract obtained by microwave-assisted extraction (MAE) presented significant contents of polyphenols (2.7 ± 0.2 mg GAE/g) and antioxidant activity (3.0 ± 0.4 mg TE/g DPPH, 4.5 ± 0.3 mg TE/g ABTS, 4.7 ± 0.3 mg TE/g FRAP). Six main polyphenols were identified by HPLC-MS/MS, showing higher contents of gallic acid (20.7 ± 1.5 mg/g) and chlorogenic acid (9.7 ± 0.5 mg/g). These results highlight the possibilities offered in the valorization of RO to obtain bioactive compounds with antioxidant performance in several applications.
... In the case of wood, the cell wall polymers cellulose, hemicellulose, and lignin act as the main components. The chemical composition of these components and any resulting change in the individual components lead to a change in the properties of the wood (Rowell 2012). The two "superordinate" sample types used in this work (thermally modified and native beech veneers) are derived from the same tree species, namely European beech (Fagus sylvatica). ...
In this study, the possible influences of thermal modification of wood on the quality of laser texturing of beech veneers are investigated by comparing native and thermally modified samples. By varying the process parameters of a CO2 laser, the surfaces of both types of veneer were textured and the resulting surface roughness and aspect ratios were analyzed in order to evaluate the efficiency of the laser texturing and the quality of the textures produced. The main results show that the thermal modification of the wood influences the cutting widths, the removal depths, and the surface roughness, with thermally modified veneers generally having larger cutting widths and different removal depths compared to native veneers, indicating the influence of the wood modifications on the material physical and chemical properties and their interaction with the laser processing. Furthermore, the study shows how the laser processing parameters—feed rate and laser power—influence the surface quality and structural dimensions of the engraved lines, and establishes that the moisture content of the wood has a significant influence on its thermal conductivity and thus on the laser cutting process. The research work highlights the complexity of laser texturing of wood and emphasizes the need to take into account the change in the intrinsic properties of the material as a result of thermal modification.
... Another option is bonding with carboxyl groups (-COOH) in the chemical structure of humic and fulvic acids which are more prominent in the latter (Delicato, 1996). Of the three main constituents of fibre cell walls, cellulose, hemicellulose and lignin, hemicellulose is the most hydrophilic substance due to its open structure and free hydroxyl groups, followed by cellulose which has three accessible hydroxyl groups when the polymers are not stacked to form crystalline microfibrils (Rowell, 2005;Stevens, 2010;Sweygers et al., 2022). Lignin has a hydrophobic nature and is of little importance to the water retention capability of fibres, though still attracts water better than crystalline cellulose which shows no adsorption at all (Kay and Goit, 1977;Baillie and Jayasinghe, 2004;Stokke et al., 2013;Sweygers et al., 2022). ...
... In this case, the study showed that the amount of water in the bamboo samples varied, with averages of 23%, 17%, and 26% [37,38]. According to [39], there may be variations in the amount of lignin present. Lignin is known for its ability to keep water away. ...
The exceptional strength-to-weight ratio, abundance and biodegradability of Semantan bamboo (Gigantochloascortechinii) have made it a popular choice as both a template material for composite manufacturing and an ideal candidate for utilization as an adsorbent material. The objective of this study was to obtain cellulose of excellent quality from bamboo fiber, considering its purity and optical qualities, which are important for various industrial. The bleaching phase, which is crucial for determining the quality of cellulose, was optimised using the response surface methodology. The parameters of NaClO2 concentration (12 – 20% w/w), temperature (60 – 80°C), and duration (3-5 hours) were adjusted to achieve optimal results. The results showed that using high concentrated NaClO2 or prolonging the bleaching period resulted in cellulose oxidation and decreased efficiency. The ideal conditions for bleaching bamboo fiber were determined to be a concentration of 16% (w/w) NaClO2 at a temperature of 70°C for 4 hours. Under these conditions, the amount of cellulose produced was as high as 45.9%. The crystallinity degree yielding results of 57.87% and 64.29% for untreated and treated bamboo fiber, respectively. The effectiveness of the delignification and mercerizastion processes in producing valuable industrial products from bamboo fiber was proven by structural analysis using morphological analysis.
... The quality of adhesion in glues depends on the fluidity of the glues, which have desired properties such as penetrating both surfaces of the wood material, distributing homogeneously on the applied surface, forming layers, and wetting the surfaces (Vıck 1999). The effectiveness of glue is expected to depend on its viscosity, molecular weight, surface penetration, amount of solid matter, pH ratio, and application method; the adhesion results also will depend on the wood material, type, density, surface roughness and cleanliness (Rowell 2005). The heterogeneous distribution of the glue on the surface where it is applied negatively affects the cohesion and causes the wood material joints to open (Smardzevski 2002). ...
Wood is a heterogeneous and anisotropic material, and its mechanical properties are different from other building materials. It is necessary to know the mechanical properties of wood materials in buildings, such as carriers, floor beams, roof timber, plywood roof covers, laminated beams, stair or wire poles, yacht poles, and furniture frames. Tensile strength is the resistance of wood material to two forces applied in opposite directions, trying to break and separate the fibers. This study aimed to determine the tension strength perpendicular to fibers of beech timber reinforced with basalt fiber-reinforced polymer (BFRP), glass fiber-reinforced polymer (GFRP), and plaster mesh (PSM). One component polyurethane (PUR-D4) and polyvinyl acetate (PVAc-D4) were used as the adhesive. The BFRP, GFRP, and PSM were added as one layer of reinforced materials. Experimental materials reinforced with BFRP, GFRP, and PSM were tested in the unreinforced locations, of reinforced lumber with BFRP, GFRP, and PSM. Tests were performed to investigate the tensile strength perpendicular to fiber (┴σt). The test results showed that the reinforcement process increased the (┴σ). The ┴σt value of samples reinforced with BFRP was 13%, 32%, and 66% higher than those reinforced with GFRP, unreinforced, and reinforced PSM, respectively. Accordingly, the BFRP shows potential to serve as an option for reinforced wood structural members.
... In addition to all these positive characteristics, wood material can be negatively affected by variables including termites, bacteria, fungi, insects, sunlight, seasonal changes, rain, frost, humidity, chemicals, and fire, which can damage its physical and chemical structure. Studies are being conducted to increase the resistance of wood to the combustion and factors in the usage area (Rowell and Dietenberger 2005;Esteves and Pereira 2009;Percin et al. 2015;Fidan et al. 2016b;Reinprecht 2016;Yasar et al. 2016;Sandberg et al. 2017;Godovčin et al. 2022). ...
It is acknowledged that boron, ammonium, and nitrogenous compounds, which are used today as fire retardants, cause an increase in the hygroscopicity of wood materials. In this study, Scots pine (Pinus sylvestris L.), Anatolian chestnut (Castanea sativa Mill.), and Eastern spruce (Picea orientalis Link) woods were impregnated with 1.5% nano-sized hexagonal boron nitride (NB) according to ASTM D1413-76 (1976) standards. Flame-induced combustion (FIC), self-combustion (SC), and glowing combustion (GC) temperatures were determined. The highest retention amount was measured in spruce and the lowest was in chestnut among the wood samples taken for testing and measurement. When compared with the control samples, NB application caused an increase in SC and FIC temperatures (at higher rates). According to the glowing combustion temperature control samples, an increase was observed in chestnut and spruce and a decrease was observed in Scots pine among the samples applied with NB.
This study investigated the physical and mechanical properties of particle boards prepared from the lops and tops of poplar (Populus deltoides) using Radio frequency (RF) pressing and urea-formaldehyde (UF) adhesive. Boards were prepared with RF application times of 9, 12, and 15 minutes under pressures of 17.5, 21.0, and 24.5 kg/cm². Results showed that particle boards prepared at 24.5 kg/cm² with a 15-minute radio frequency application time performed well, meeting Indian Standard (IS: 3087) requirements. An inverse relationship between specific pressure (SP) and physical properties was observed, with increased SP leading to decreased moisture content, higher density, and reduced water absorption. In terms of mechanical properties, higher SP resulted in improved tensile strength (TS), modulus of rupture (MOR), modulus of elasticity (MOE), and screw withdrawal (SW) strength for both face and edge. These findings highlight the importance of specific pressure in enhancing the physical and mechanical characteristics of particle boards. Optimizing SP could lead to stronger, more durable boards, offering significant potential for improving quality in industrial applications using RF curing technology.
Wood is an important construction material, but a significant problem hindering its widespread use is susceptibility to biodeterioration and biodegradation. To protect wood against degradation, a surface coating can be used, and it is important to be able to predict the ability of the coating to prevent fungal growth. The currently available standard method to determine the antifungal efficiency of a coating has two weaknesses, viz. no evaluation of the moisture content in the wood material, and no possibility to study antifungal effect of the coating towards an individual fungus. A new quantitative method of determining the antifungal efficiency of coatings is therefore proposed, where a coating is applied to wood and exposed to an individual fungus in a Petri dish. Six commercial water-based coatings containing synthetic biocides were studied on filter paper (EN 15457) and with the new test method on wood blocks. The results show the importance of studying the antifungal efficiency of a coating using individual fungi instead of a mixture of fungi, since individual fungi interact differently with a given biocide in the coating. The moisture content of the wood substrate during the test was affected by how the fungus was established on the coating. This new test approach shows promise in screening the antifungal efficiency of wood coatings containing preservative substances applied to wood material surfaces.
Wood modification has been explored in various ways to enhance dimensional stability and reduce flammability, with a focus on environmentally friendly treatments to meet market demands. This study aimed to investigate the efficacy of new, potential fire-retardant materials. Specifically, the study examined the combination of tripotassium citrate (TPC), a water-soluble and bio-based fire retardant, with sorbitol and citric acid (SorCA), an eco-friendly thermosetting resin previously studied. While TPC is known to control combustion, its application in wood modification has not been thoroughly researched. To assess the fixation and flammability of these fire retardants, tests were conducted on Scots Pine (Pinus sylvestris L.), including chemical analysis, dimensional stability, mechanical properties, flame retardancy, and leaching tests. The combination of SorCA and TPC showed high weight percent gain (WPG) values; however, leaching and anti-swelling efficiency (ASE) tests revealed challenges in fixation stability. The dynamic mechanical properties were reduced, whereas the static strength values were in the same range compared with untreated wood. While TPC exhibited high flame retardancy prior to leaching, its efficacy diminished post-leaching, underscoring challenges in fixation and the need for improved retention strategies. Bunsen burner tests conducted on leached specimens indicated enhanced performance even under severe leaching conditions as per the EN 84:2020 procedure. However, cone calorimetry measurements showed less favorable outcomes, emphasizing the necessity for further investigation into optimizing TPC retention and enhancing treatment efficacy.
The secondary phloem of Pinus pinaster Aiton bark has sieve cells and axial and radial parenchyma, but no fibres. Resin ducts are present in fusiform rays . Stiloid crystals, starch granules and tannins occur inside sieve and parenchyma cells. The rhytidome of P. pinaster bark has a variable number of periderms forming scale-type discontinuous layers over expanded parenchyma cells. Phellem comprises 4-6 layers of thickwaIled and little suberized cells and phelloderm a layer of 2 or 3 thickened lignified ceIls and a layer of expanded cells.
When woody plants once covered most of the earth’s surface, they provided not only food, warmth, and shelter, but many of the needs of defense, medicines, culture, and simple pleasures. Some needs could be readily satisfied by using “minor forest products” such as resins for caulking boats, for use in torches, or for providing rigidity in the attachment of spear, arrow, or axe-heads to the shaft before the joints were finally lashed with fibrous material (24). Such resinous products could be provided by a number of sources and a few trials would reveal their effectiveness. Other materials, such as kinos or tannin extracts, when used as astringents for the treatment of diarrhea, would require a more sophisticated knowledge.