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resin content of different wood types and cell wall locations at various conditions and impregnation regimes; larch ¼ Larix decidua Mill., pine ¼ Pinus sylvestris L., spruce ¼ Picea abies [L.] Karst
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Melamine-formaldehyde (MF) resin impregnation has shown considerable potential to improve a number of wood properties, such as surface hardness and weathering resistance. In this study, selected factors influencing the uptake of MF resin into the cell wall of softwood were studied. Using UV-microspectroscopy, it could be shown that water soluble MF...
Contexts in source publication
Context 1
... higher MF concentrations distinct peaks appeared around 240 nm. Table 1 lists MF contents (v/v) determined in late- wood secondary walls (S2) from sapwood and heart- wood of three species. Measurements were done at different impregnation durations, wood types, cell wall locations and impregnation regimes. ...Context 2
... (1964) gives a calculated maximum volumetric swelling in organic liq- uids of the cell wall of about 38%. This number is in the range of the observed 24% (v/v) MF resin in spruce sapwood after 20 h of penetration (Table 1). ...Context 3
... consistently lower MF concentration was found in heartwood compared to sapwood (Table 1), with the difference being more pronounced in larch than in pine. This is in agreement with Bailey and Preston (1969) who reported for Douglas fir a markedly lower concentration of silver grains in heartwood cell walls compared to sapwood. ...Context 4
... water in cell wall capillaries through increasingly less polar liquids with low surface tension, the collapse of these pores may be partially prevented, with a certain level of porosity preserved dry (Stamm, 1964;Bower and Wellons, 1974). Results obtained in this study show that the MF uptake was increased due to solvent exchange drying (factor of 2.5), however, the increase was not dramatic (Table 1). Since similar impregnation results were achieved with fully water saturated cell walls, the feasibility of solvent exchange drying as a possible pre- treatment to increase resin uptake can be questioned. ...Context 5
... measurements show that more MF resin had penetrated fully water saturated spruce cell walls after 1 h, than dried cell walls after 20 h. The initial difference progressively disappeared with increased duration of impregnation (Table 1, Fig. 3). The initial difference in resin uptake might be explained by the fact that MF resin per se cannot penetrate into dry cell walls. ...Context 6
... are showing that drying of the cell wall from its native, fully water satu- rated state leads to an unrecoverable loss of porosity (Tynj€ a al€ a a and K€ a arenlampi, 2001). In our study this phenomenon had no or only a minor effect on the im- pregnation of cell walls using MF resin (Table 1). ...Context 7
... final aspect investigated in this study was the effect of resin concentration on the penetration of MF resin into dry cell walls. Presence of water enhanced impregnation and more than twice the resin content was found in the cell walls after treatment with 25% resin, compared to impregnation with 55-60% resin (Table 1). With this, it has to be taken into account that increased viscosity at higher resin concentrations may have con- tributed to the slower resin uptake. ...Similar publications
Tuning the supramolecular morphology of an equimolar complex of riboflavin and melamine by the in situ formation of different size silver nanoparticles, affecting the photoluminescence property.
Citations
... Semakin tinggi konsentrasi maka penetrasi semakin tinggi. Sementara pada impregnasi melaminformaldehida, semakin tinggi kandungan air di dalam kayu, semakin encer larutan melamin-formaldehida dan semakin sedikit kandungan ekstraktif kayu maka penetrasi semakin tinggi [20]. Dari hal-hal tersebut dapat diperkirakan bahwa berbagai hal dapat mempengaruhi penetrasi reagen ke dalam interior kayu. ...
... MF berukuran molekul kecil sehingga mudah menembus hingga area amorf selulosa, dinding sel sekunder dan lamella tengah. Penetrasi lebih tinggi bila kayu dalam keadaan basah [20]. ...
Buku ini menjelaskan kayu dari sisi kimianya sehingga mampu dimodifikasi terutama memperbaiki sifat dan kegunaan dari kayu yang diinginkan
... Cell wall bulking was calculated using the transverse (radial and tangential) section. Thus, it indicates the extent to which the cell wall swells, signifying that the cell wall remains swollen after curing [82,83]. This change is due to the bulking of the precipitated chemicals [2,6], which is expressed as an increased volume in the specimen under ovendry conditions. ...
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.
... Thermosetting resins used in wood modification have special properties that allow them to penetrate the water-swollen wood cell wall, causing the wood to bulk up [100,101]. During heat curing, the solvent evaporates, and the resin monomers and oligomers polymerize, becoming water insoluble and securely fixed within the wood. ...
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.
... This reaction causes significant changes in wood at the molecular level which are visible by infrared spectroscopy (Fodor and Hofmann 2024;Gaitán-Alvarez et al. 2020;Mohebby 2008) and also Raman spectroscopy (Digaitis et al. 2021;Ponzecchi et al. 2022). Alternatively, attempts to induce chemical changes are made using melamine resins (Altgen et al. 2020a,b;Behr et al. 2018;Gindl et al. 2003;Sultan et al. 2024). Melamine formaldehyde resins (MF) are synthesised by the condensation reaction of melamine molecules with formaldehyde in water (Pizzi 2003). ...
... Vacuum-pressure impregnation allows the MF solution to enter the lumens of the wood matrix. A subsequent diffusion phase allows the impregnation solution and the included monomers to enter the cell wall cavities (Gindl et al. 2003;Rapp et al. 1999). The reaction, when carried out at elevated temperature, produces hydrophobic intermediates, the molecular size of which is increased through the presence of methylene and ether bridges (Pizzi 2003), forming irreversible fixation points with the wood structure (Rapp et al. 1999). ...
Wood modification (by thermal or chemical treatment) helps to improve the dimensional stability of wood and enhance its resistance to biological agents. Beech wood is non-durable and exposure in exterior settings dramatically shortens its service life. To determine the full potential of beech wood for advanced applications, a better understanding of the chemical changes induced by modification is needed. Two chemical treatments (acetylation and melamine formaldehyde resin impregnation) and three thermal treatments (heating to 180, 200 and 220 °C) were performed on beech wood. The modification effect was examined based on (i) molecular changes in functional groups by Fourier-transform infrared spectroscopy (ATR-FTIR); (ii) extractive content; and (iii) pH changes. Moreover, the explanation of these changes was supported by the FTIR-analysis of isolated main wood components (cellulose, holocellulose and lignin) from the modified wood. The high temperatures applied to samples during thermal modification promoted the deacetylation and degradation of hemicelluloses. Hemicelluloses were targeted also by acetic anhydride and melamine resin, the bonding of which was confirmed by FTIR analysis. The formation of fewer methylene bridges affected the properties of the melamine network. This observation suggests the need to determine optimal curing conditions in future research, to reduce melamine-wood hydrophilicity.
... Major health hazards resulting from illegal melamine adulteration are kidney stones and kidney failure in the infants [2]. A number of products which are in daily use, manufactured from melamine, include wide range of plastic goods, resins, polymers and coatings [3]. The culprits for melamine adulteration in milk try to enhance protein content [4]. ...
Melamine is being added in pet food, milk and infant formula to enhance its “false” apparent protein contents but when it is present in milk beyond its allowed limit, it causes serious health problems which leads to renal failure and kidney stones. In this work a highly selective, sensitive and rapid method has been developed for determination of melamine as potential milk adulterant. Ag-MOFs doped with magnetic nanocatalyst were synthesized by using chemical reduction method and characterized through UV-Vis spectroscopy, Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). The strong SPR peak of Ag-MOFs was observed at 400–500 nm and Fe-SnO2 was observed at 250–300 nm. The absorption band of Ag-MOF@Fe/SnO2 was found at 250–350 nm with energy band gap of 2.78. The average particle size of nanocomposite was found to be 54.11 nm having uniform and crystalline shape. Different factors i.e. adsorbent dose, adsorbate dose, pH, temperature and time were optimized for maximum sensing of melamine. Prepared nanocomposite showed 97% detection efficiency for melamine at pH = 8 and 45 °C temperature in time limit of 25 min. Feasibility of prepared nanocomposite was also checked by standard melamine samples and pre-treated spiked milk sample. Prepared nanocomposite gave a rapid sensitive detection of melamine with limit of detection 1.8 ppm and 77% recovery from spiked raw milk without using any costly instrument.
Graphical Abstract
... [15][16][17][18] Adhesives have an extensive range of applications in furniture, packaging, electronics and construction, and a high number of wood adhesives are inevitably used in the production of wood composites, such as plywood, particle board, and bre board. [19][20][21][22][23] However, most of the wood adhesives used in the production of wood composites are aldehyde-based, such as urea-formaldehyde, phenol-formaldehyde, and melamineformaldehyde resins, [24][25][26] which inevitably release formaldehyde, a carcinogen that has a severe impact on human health during production and use. This problem poses a serious challenge to applying traditional adhesives, thus developing non-toxic, environmentally-friendly, and biodegradable biobased adhesives is of far-reaching signicance. ...
2-Pyrone-4,6-dicarboxylic acid (PDC) is a chemically stable metabolic intermediate of lignin, and its condensation polymers can be synthesized by utilizing the functionality of two carboxylic acids. In this study, biodegradable PDC-based polyesters, namely, P(PDC2) and P(PDC3), with strong adhesive properties toward wood were developed by polycondensation with diols. The adhesive properties of P(PDC2) and P(PDC3) were fully characterized by tensile lap shear strength measurements, X-ray photoelectron spectroscopy, and cross-sectional computed tomography. The biodegradability of P(PDC2) and P(PDC3) in natural pond water was also measured. Both P(PDC2) and P(PDC3) showed strong adhesive strengths to wood with the highest average adhesion of 5.55 MPa, which usually causes wood failure. In order to quantitatively investigate the adhesive strengths of P(PDC2) and P(PDC3), decomposition acceleration experiments were performed. The average adhesive strength of 2.57 MPa remained even after immersion in hot water at 60 °C for 4 h, which demonstrated the excellent adhesive strength and water resistivity of the PDC-based polyesters. P(PDC2) and P(PDC3) remained almost uniformly biodegraded after 60 days of incubation in a simulated natural environment and reached a biodegradation rate of about 54% and 52%, respectively. The excellent adhesive properties and biodegradability of the PDC-based polyesters provide a new strategy for preparing safe and environmentally-friendly bio-based adhesives.
... In wood, the most common natural polymers are lignin, different forms of hemicelluloses and celluloses. Wood has an important function in today's society [2]. It is utilised as a fuel in factories, commercial structures, and in the manufacture of various products for residential use. ...
... Softwood have generally lower density and found lighter in color. [2] They usually grow faster in comparison to hardwoods and they are soft and easier to work. Due to the dimensional property and lack of strength softwood is mainly used in fuel purpose. ...
... Finally, the wood impregnated with the resin solution was heat-cured to polymerize the impregnated resin. Several studies have suggested storing impregnated wood under moist conditions prior to curing to allow the resin to diffuse into the cell walls (Hill 2006;Stamm and Seborg 1941), because the resin diffuses more smoothly into the cell wall in its swollen state (Gindl et al. 2003). However, some reports (Klüppel and Mai 2013) indicate that storing impregnated wood under non-drying conditions promotes polycondensation of the resin, thereby reducing cell wall penetration and bulking. ...
The resin impregnation treatment of wood is used as a pretreatment to improve the deformability of wood and the durability of its formed products. The objective of this study was to clarify the effect of solvent removal after resin impregnation on wood deformation. A solution of melamine formaldehyde (MF) resin was impregnated into the wood, and the solvent was removed from the wood under vacuum or different relative humidity (RH) conditions. The deformability of MF-resin-impregnated wood was evaluated based on the load required for molding. A higher RH during solvent removal allowed the MF resin to penetrate the cell wall, while the polymerization of the MF resin impregnated in the cell lumen and cell walls was accelerated. Polymerization of the impregnated resin significantly reduced the deformability. The cell orientation and distribution of the MF resin at the cellular level in the molded products were evaluated by X-ray diffraction and Raman mapping. The results showed that the higher the RH during the solvent removal process, the higher the cell orientation and amount of resin in the cell wall. These results suggest that the solvent removal process after resin impregnation has a significant effect on deformability during deformation processing and the formed products.
... Other treatment with chemical components and different types of resin impregnation (DMDHEU, melamine, phenol, furfuryl) were investigated by e.g. [19,13,21,14,11,17] and many more. Beside of the published study from [4] using alkaline, densification and partial extraction of wood polymers will attract attention. ...
... Thermosetting resins used for wood modification purposes are characterized by their molecular weight (size) and polarity, which allows to enter the macropores (cell lumen) but also the nanopores of the water-swollen wood cell wall [255,262,[273][274][275][276][277]. Similar to other impregnation modification techniques, treatments with thermosetting resins create a bulking effect (CWB), as the cell wall is set in a permanent swollen state when resin molecules polymerize within the cell wall ( Figure 8). ...
Wood modifications are becoming popular as a way to enhance the performance of wood, either to make it more durable, improve the performance of wood, or give it new functionality as a multifunctional or smart material. While wood modifications have been examined since the early 1900s, the topic has become a dominant area of study in wood science over the past decade. This review summarizes recent advances and provides future perspective on a selection of wood modifications, i.e., the methods that are currently commercialized (acetylation, furfurylation, and thermal modification), a rediscovered ancient practice (charring), a family of polymerization modifications that have so far made it to the pilot scale, and examples of novel wood-based functional materials explored at laboratory scale.
