The global shift toward sustainable development has increased the demand for renewable biomass materials, with rubberwood emerging as a promising resource due to its rapid growth and potential for carbon sequestration. However, its susceptibility to dimensional instability and decay has significantly hindered its widespread industrial application. While current solutions address certain challenges, they often come with disadvantages such as high costs, inefficiencies, and/or environmental risks. This study introduces an innovative heated platen modification method designed to overcome these limitations. By employing direct-contact heating, a rapid surface modification is achieved between 5 and 15 min at temperatures ranging from 250 to 290 degrees C. It creates a functionally graded material structure that enhances surface properties while maintaining core strength. Compared to untreated materials, the treated specimens exhibited a 524 kg/m3 increase in surface density, a 29-47 % reduction in modulus of rupture, a 2-11 % decrease in modulus of elasticity, a 2-31 % drop in screw holding power, a 33 % reduction in shrinkage, and a 58 % decrease in swelling. Surface natural decay resistance performance improved significantly, with a 39-45 % decrease in mass loss rate. Mechanistic analysis revealed that selective hemicellulose degradation and lignin redistribution enhanced the overall degree of crystallinity from 40 % to 64 % without compromising the crystalline domains, collectively improved dimensional stability and decay resistance without severe strength compromise. A key contribution of this study is establishing quantitative correlations between color parameters and performance metrics, revealing strong relationships between Delta E* and mechanical properties, chemical composition, and dimensional stability, and suggesting the chromatic indices as viable proxies for performance evaluation. However, predicting fungal durability via color requires further study due to decay mechanism complexities. This work advances the sustainable utilization of plantation species by integrating controlled surface modification, performance enhancement, and nondestructive assessment, offering a paradigm for efficient wood processing aligned with circular economy principles.

Grafting-onto modified cellulosic materials using reactive ionic liquids (RILs) is emerging as a green and versatile strategy to tailor surface chemistry and functionality. This paper investigates the process–structure–property relationships of quaternised celluloses using glycidyltriethylammonium chloride (GTEAC) as a RIL, and microfibrillated cellulose (MFC) and nanocrystalline cellulose (NCC) as core materials. The resulting quaternised materials, QMFC and QNCC, exhibited distinct chemical and structural changes confirmed by FTIR, SEM/EDX, and WAXS/SAXS. The chain-growth polymerisation of GTEAC on MFC or NCC led to a substantial reduction in crystallinity, or an increase in the amorphous content (QMFC: from 85

The anisotropic apparent diffusivity as a function of the flow rate was determined in a series of Dynamic Vapor Sorption (DVS) experiments on spruce samples in the three orthotropic directions. Four different fitting procedures were applied for the evaluation of the time-sorption isotherms, i.e., the double-stretched exponential (DSE), the Ritger-Peppas (RP), and the Fickian and double-Fickian (SUM/DSUM) fitting methods, together with a derivative (DER) method for the determination of the apparent diffusivity. The results confirm that the DER method delivers similar results to the DSE fitting procedure, i.e., 1.98·10− 10, 0.94·10− 10 and 1.00·10− 10 m2/s for the longitudinal, radial and tangential direction, respectively, with a maximum of 10% deviation, in a much simpler manner.

The effects on the measurement of water sorption and apparent diffusivity when using different flow rate values and different experimental setups, i.e., closed pan, open pan and hanging setup, have been studied in a series of Dynamic Vapor Sorption (DVS) experiments on a spruce sample. The results confirm a concave exponential growth dependency between apparent diffusivity and flow rate and an effect from the setup used, with the hanging setup being optimal for conducting such experiments due to the exposure of both areas of the disk to the airflow.

Understanding the pore characteristics of wood is crucial for studying the micro- and macroscopic physical properties of this biomaterial and for predicting how effective any modification method would be. There is a need to better understand and determine the pore structure of wood materials. However, due to the wide pore size distribution (PSD) and its complexity, a single structural characterization method is usually insufficient for accurately interpreting the wood structure. In this study, the pore structure of wood is evaluated using a combination of X-ray computed tomography (XCT), nitrogen adsorption (N2A), and mercury intrusion porosimetry (MIP), and the structural information is analyzed, compared and discussed in detail. Due to the voxel size of 2.00 mu m3 on the detection scale, the porosity measured by XCT was slightly lower than that obtained from MIP and N2A - which can reach the nanometer detection level -, with N2A being the method that yields the highest porosity. Although the PSD and the related parameters from the three methods differ, they are still capable of distinguishing between different wood species, and the average pore diameter and PSD obtained from the three different methods are similar, as well as the fractal dimension. Finally, the specific surface area values of the different wood species measured by N2A range between 1 and 2 m2/g. The combined characterization of numerous approaches, following their respective requirements, can provide a more comprehensive analysis of the intricate pore structure of wood materials.

When producing load-bearing timber products with one-component polyurethane adhesives and certain wood species, e.g., beech or larch, primers can be used to obtain stronger and more durable bonds. The active chemicals of three existing primer systems, hydroxymethylated resorcinol formaldehyde (HMR), polysorbate 20 (PS20), and poly(ethylene glycol) (PEG), were used to impregnate beech wood. Young’s modulus (E) in the radial direction was determined in tensile mode. A modified E can influence the deformation and stress distribution at the wood-glue interface. Compared to the untreated wood, the average E was reduced by 7% for the water-treated reference and the HMR treatment. With the PS20 treatment, the average E was reduced by 16%, compared to the untreated wood, and by 45% with the PEG treatment.

The permeability of wood materials significantly affects wood modification, drying and further processing of wood-based building materials, and there is a need for a better understanding and evaluation of the permeability of wood materials. This paper presents a novel method for estimating the macroscopic permeability in wood by combining mercury intrusion porosimetry (MIP) data with the fractal theory. The characterization of wood’s structural parameters through MIP provides essential geometric data for the subsequent modelling process. A computational model for permeability was established based on principles of fractal geometry and seepage flow theory. This model aimed to elucidate the relationship between the structural characteristics of wood and its permeability behaviour. By deriving an explicit expression for permeability, the model incorporated critical structural parameters, e.g., minimum and maximum pore size, pore size distribution, porosity, fractal dimension, and the fractal dimension associated with tortuosity. The permeability of the three wood species studied, i.e., Scots pine, white birch, and oak, was 28.6, 13.6 and 1.4 mD, respectively. To validate the model, the calculated permeability values were compared with experimentally measured data, showing a strong correlation and confirming that the model accurately reflects the permeability behaviour of wood based on its structural characteristics. Notably, the model demonstrated the effectiveness of utilizing MIP data in conjunction with fractal theory, thus, the computational efficiency of this method significantly surpassed that of traditional numerical simulations, which allowed a better understanding of the interplay between structure and permeability in wood.

In regions where microbial contamination of groundwater and surface water remains a significant public health concern, leading to around 505,000 annual deaths, there is an urgent need for accessible, cost-effective, and simple household water treatment solutions. This study investigated the feasibility of wood as a filtration system, with a focus on its ability to remove nanoparticles. The research underscores the remarkable potential of wood filters, particularly in radial and tangential directions, exhibiting superior particle removal capabilities (> 99

This paper concerns the viscoelastic properties and the resulting structure of colloidal systems with short-range attractions in the regime where the volume fraction f is small. Unlike the high ϕ regime, which is well understood in terms of mode-coupling theory (MCT), the low ϕ regime is still the subject of a debate based on different concepts such as percolation, diffusion-limited colloidal aggregation (DLCA), jamming, or cluster mode-coupling approach. Prior to the analysis of three examples of attractive systems at low ϕ values, a summary of concepts relevant to understanding the formation and properties of such attractive particles is discussed in the present study. Afterwards, we re-analyze the behaviour at a low ϕ of i) suspensions of carbon black (CB) particles, ii) suspensions of poly(methyl methacrylate) (PMMA) hard spheres with a depletion attraction induced by the addition of polystyrene (PS), and iii) suspensions of amino acid organogelator molecules which form rod-like objects. The rheological properties of these systems have been studied in detail and their response has been interpreted as being due either to a solid network discussed in relation to the jamming state diagram or to a suspension formed by jamming of clusters. Our analysis shows that these three systems are in fact cluster fluids and that their solid-like response corresponds to a change in their viscoelastic response, the elastic component G' becoming greater than the viscous component G" at low frequencies. Due to the presence of weak interparticle interactions in the tens range from 1 to 15 kBT, a liquid-like state is reversibly achieved at high frequencies, as indicated by the crossover of G' and G" as a function of frequency for a given concentration. Moreover, all these attractive particle systems at low ϕ show for both moduli a master curve which characterizes these cluster fluids and allows for the classification of these attractive particle systems.

Microfibrillated cellulose (MFC) was functionalised using a reactive ionic liquid monomer, i.e., glycidyltriethylammonium chloride (GTEAC), via chain-growth polymerisation, resulting in a novel cationic polyelectrolyte-grafted quaternised MFC (QMFC). The degree of quaternisation and maximum ion exchange capacity of the resulting QMFC were 2.13 mmol/g (i.e., 132 mg/g) and 1.51 mmol/g (i.e., 94 mg/g), respectively. Small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) experiments confirmed the retention of monoclinic crystalline structure for cellulose I with the corresponding decrease in the degree of crystallinity from 85% to 56% and the increase in the spacing between cellulose crystallites by 35%. The presence of the amorphous and grafted polymers was confirmed by microscopy, thermal analysis, and water sorption experiments. QMFC filter cartridges were prepared and tested under dynamic flow conditions with a pressure of 0.2 MPa (retention time of 0.5 min). These cationic polyelectrolytes enhanced multi-site ion exchange interactions as evidenced by the Freundlich sorption isotherm. The QMFC filter cartridges demonstrated high anion removal efficiency values of 83.2%, 98.1%, and 94.9% for NO3-, SO42-, and PO43-, respectively. This system achieved a process mass efficiency of 2.79, an E-factor of 1.97, and an energy efficiency score of 66.3, which conforms to the green chemistry principles and demonstrates high potential for sustainable water purification.

For the utilization of silver birch ( Betula pendula R oth ) in load-bearing engineered wood products (EWPs), reliable bonding in production is a prerequisite. The current knowledge regarding the bonding of birch in EWP applications is limited. Extractives are considered a general factor of attention when securing bonding quality. Thus, in this study, the effects of hydrophilic extractives on several adhesion-related bulk and surface properties of silver birch wood were studied, e.g., vapor sorption, swelling behavior, microstructure, wettability, and mechanical properties. The extraction procedure slightly affected vapor sorption causing a reduction in swelling pressure. The extraction also led to a lower Young's modulus, as seen by compression tests. Control experiments with vapor-treated specimens, however, indicated that the effects were originating from the water imbibition and not due to the removal of extractives per se. This was supported by X-ray diffraction results, which were similarly affected by both vapor and extraction treatment. Therefore, the results indicate that the hygric history of the specimens was affecting the wood due to plasticization, increasing mobility, and thereby likely allowing biopolymer reconfiguration and subsequent quenching during re-drying, even though surface-free energy and wettability were not considerably affected. The extent to which these changes appear permanently or temporarily remains an open research question.

While bonding for structural applications in Europe was limited to only a few softwood species in the past, forest alterations toward more climate stability will increase the diversity of tree species. This requires an understanding of typal wood-adhesive interactions. To help facilitate birch wood bonding, its cold-water soluble extractives and their effects on mechanical performance and bond line morphology were studied using water-borne melamine-urea-formaldehyde (MUF) and hydrophobic solvent-free polyurethane (PUR) adhesives. Extractives classes were identified via mass spectrometry and their concentration and extraction kinetics were evaluated. The analysis revealed that the mechanical properties of the bond line were essentially unaffected by extraction when using the hydrophobic PUR adhesive. Increased degrees of extraction resulted in reduced MUF penetration, and slightly thicker bond lines, however, the mechanical results indicate improved performance, indicating fewer defects in the cured adhesive network.

Unilateral surface compression in wood presents notable benefits, including reduced wood volume loss and energy consumption, rendering a highly promising and extensive utilization. However, shortcomings in compressed wood arise due to unclear gas pressure, temperature, and moisture content distribution within the wood during hot pressing. In this paper, the temperature and pressure distribution were analyzed utilizing an optical fiber temperature and pressure measurement system within the wood during hot pressing. Moreover, the moisture content, stress and strain in each layer at the end of hot pressing were discussed extensively. The results showed that the wood surface layer (SL) and subsurface layer (SSL) maximum temperature values were similar even with different layer thicknesses. Under sealing conditions, SL and SSL temperatures were generally 6 degrees C to 7 degrees C higher compared to unsealing conditions. The gas pressure maximum value exhibited an opposite order, gradually transferring to the core layer (CL) and declining as the processing time extended. During compression treatment, moisture migrated from the hot end to the cold within the wood. The moisture content displayed significant differences between the middle and end parts of the wood under unsealed conditions, with the disparity becoming more pronounced further away from the hot end. The transition region of the compressed wood served as a stress concentration area, experiencing the highest levels of stress. The dense region followed with the second highest stress levels, while the un-densified region exhibited the least amount of stress. Under the same process parameters, the thickness had little influence on the distribution of dense layers.

Lignocellulosic materials, despite their abundance and attractiveness, have long been marred with challenges in optimising the cost-functionality-quality trade-off. This comprehensive authoritative review paper explores how various lignocellulosic feedstock have been utilised to prepare marketable and sustainable bioplastics, as potential substitutes to conventional petroleum-based packaging. Dependence on hydrocarbon-derived plastics is increasingly being supplanted by both consumer-driven and sustainability-oriented materials design. This comprehensive paper encompasses a broad review relating to recent research (2013−2023) on the innovations and heuristic approaches to modify lignocellulose for the production of packaging films. The review paper holds extensive focus across various lignocellulosic materials such as - but not limited to - cellulose nanomaterials, cellulose esters and grafted cellulose. Advances in processes reported to date such as mechanochemical, chemical, thermochemical, biochemical and other novel methods have been studied. The materials design and process implications in terms of its cost, energy input and sustainability in its true sense, for all known techniques have been extensively investigated in this review paper. The review paper has further provided an elaborate process-structure-property-performance framework that characterises how material properties could be fine-tuned via different process considerations. A techno-economic feasibility overview for said processes and materials' use is also described herein.

This study investigated how water-soluble extractives of silver birch (Betula pendula ROTH) wood interact with the most common adhesives used for producing engineered wood products (EWPs), i.e., melamine-urea-formaldehyde (MUF) and one-component polyurethanes (PUR). Therefore, the extractives were characterized via various chromatographic techniques and mass spectrometry. The effects of extractives on the curing kinetics were investigated using rheometry. The impact of extractives on the chemical and mechanical properties of the cured adhesives was investigated with FTIR spectrophotometry and tensile stress-strain measurements, respectively. Moreover, a comparative study on the shear strength of birch wood with and without extractives was performed. The organic fraction of the water extractives of birch mainly consisted of phenolic glycosides, carboxylic (fatty) acids, and saccharides. The extractives decelerated the curing process of MUF, as observed in a rheological small-angle oscillatory shear experiment using wood substrates as the lower plate. This was indicated by a reduced gel time from 5 to 3.8 h on pristine vs. extracted wood. When measuring MUF on extracted wood, this deceleration was also reached by adding similar to 1% (W/W) of the isolated extractives into the MUF resin. Similar experiments with PUR showed a slight acceleration when dispersing extract into the adhesive, indicated by a reduction of vitrification time of -0.9 +/- 0.3 h per percent of extractives added. However, measurements with pure PUR on pristine and extracted wood showed no significant difference in curing kinetics due to the extractives' limited mobility and solubility in PUR. Both PUR and MUF cured adhesive films showed a reduced stiffness, elastic stress limit and tensile strength in uniaxial tensile stress-strain measurements of adhesive films upon increasing the amount of hydrophilic birch extractives concentration. Comparative standard tensile shear strength measurements on pristine and extracted wood indicate a 7-19% strength increase due to extraction when bonding with MUF, while the bond strength of PUR bond lines was less affected by the extraction procedure.

Gravimetric vapor sorption experiments were performed on beech wood samples to determine the directional permeability, diffusion and sorption coefficients in the three orthotropic wood directions. Dynamic Vapor Sorption (DVS) experiments allowed for the direct evaluation of the diffusion coefficient from the analysis of the kinetic sorption profile using a double stretched exponential model with values ranging from 0.10 × 10−10 to 1.52 × 10−10 m2/s and depending on the wood direction of the sample and the RH-values. Moisture sorption isotherms (MSIs) were constructed and fitted to a modified Guggenheim-Anderson-de Boer and a Sorption Site Occupancy model, which allowed for the calculation of the sorption coefficient which was found to be between 2.4 and 3.0 mol/(m3 Pa). Dynamic Vapor Transport (DVT) experiments were performed to calculate the permeability coefficient from the vapor flow rate and it ranges between 0.56 × 10−10 and 4.38 × 10−10 mol/(m s Pa) as a function of the flow direction and RH conditions. These results indicate that such an experimental approach is suitable for determining wood–moisture interactions.

Today, using one-component polyurethane (1c-PUR) adhesives in the manufacturing of engineered wood products from spruce is common practice. However, the use of other wood species can require the application of a primer to fulfill normative requirements. Previous research shows the primers’ effectiveness, especially in moist environments. However, the primers’ exact mode of action remains not yet fully understood. We hypothesize a reduction in the hygroscopic behavior of the primer-treated wood—intensity and kinetics—that could reduce the formation of stresses in the bond line region. To test this hypothesis, two commercially available primers, based on Polysorbate 20 and poly(ethylene glycol), and the hydroxymethylated resorcinol (HMR) primer are examined with wood from beech, birch, larch, and Douglas fir. Swelling experiments show that of each primer a portion infiltrates and swells the wood cell walls, affecting the wood’s hygroscopic and mechanical properties. In stepwise sorption experiments, it is seen that the primers influence differently the amount of moisture uptaken by the wood (adsorption). The rate at which the moisture spreads within the wood (diffusivity) also changed differently for the primers, while the rate at which the moisture moves through the wood (permeability) remains unchanged. The application of all primers improves the bulk flow behavior and thus the void penetration of the adhesive into the lumina in the interphase region, which in turn leads to a reduced bond line thickness. All three primers improve the tensile shear strength. The hygroscopic changes caused by the primers appear too small to be claimed as the sole and primary cause of their functionality, whereas more relevance is seen in the primers’ cell wall infiltration and the increased adhesive’s void penetration.

Background Hot extrusion is widely used to produce iron-fortified rice, but heating may increase resistant starch and thereby decrease iron bioavailability. Cold-extruded iron-fortified rice may have higher bioavailability but has higher iron losses during cooking. Thus, warm extrusion could have nutritional benefits, but this has not been tested. Whether the addition of citric acid (CA) and trisodium citrate (TSC) counteracts any detrimental effect of high-extrusion temperature on iron bioavailability is unclear. Objectives Our aim was to assess the effects of varying processing temperatures on the starch microstructure of extruded iron-fortified rice and resulting iron solubility and iron bioavailability. Methods We produced extruded iron-fortified rice grains at cold, warm, and hot temperatures (40 degrees C, 70 degrees C, and 90 degrees C), with and without CA/TSC at a molar ratio of iron to CA/TSC of 1:0.3:5.5. We characterized starch microstructure using small- and wide-angle X-ray scattering and differential scanning calorimetry, assessed color over 6 mo, and measured in vitro iron solubility. In standardized rice and vegetable test meals consumed by young women (n = 22; mean age: 23 y; geometric mean plasma ferritin: 29.3 mu g/L), we measured iron absorption from the fortified rice grains intrinsically labeled with (57)ferric pyrophosphate ((FePP)-Fe-57), compared with ferrous sulfate ((FeSO4)-Fe-58) solution added extrinsically to the meals. Results Warm and hot extrusion altered starch morphology from native type A to type V and increased retrograded starch. However, extrusion temperature did not significantly affect iron solubility or iron bioavailability. The geometric mean fractional iron absorption of iron from fortified rice extruded with CA/TSC (8.2%; 95% CI: 7.9%, 11.0%) was more than twice that from extruded rice without CA/TSC (3.0%; 95% CI: 2.7%, 3.4%; P < 0.001). Conclusions Higher extrusion temperatures did not affect iron bioavailability from extruded rice in young women, but co-extrusion of CA/TSC with FePP sharply increased iron absorption independently from extrusion temperature. This trial is registered at as NCT03703726.

Emulsion polymer isocyanate (EPI) adhesive is one of the most widely used structural adhesives in the woodworking industry. However, there has been a lack of knowledge on how the EPI-adhesive interacts with the chemical constituents of wood, in particular, with the wood extractives that are known to influence the bonding quality. In this study, the interactions of the EPI-adhesive with the water extracts and selected extractives from European wood species were systematically investigated using different analytical techniques. While the alterations in the curing properties of the pure EPI-adhesive and EPI-adhesive-extract mixtures were revealed by in situ rheology and Fourier-transform infrared spectroscopy, evolved gas analysis, and pyrolysis-gas chromatography/mass spectrometry, the solid-state C-13 nuclear magnetic resonance were performed for analyzing the final chemical composition of the cured adhesive. Moreover, the influence of the extraction on the mechanical bonding performance was tested by tensile-shear tests. The study revealed significant interactions between the EPI-adhesive and tannin-rich, acidic wood extracts. The acidic chestnut and oak extracts catalyzed the curing reactions and led to a huge increase in the adhesive viscosity. These interactions might affect the bonding quality, for example, adhesive penetration depth and formation of bonding strength, therefore, careful attention is required when bonding acidic wood surfaces.

A hydroxymethylated resorcinol (HMR) primer was developed in the 1990s to improve the performance of epoxy-bonded wood lamellas for use in moist conditions. Its chemical composition resembles a strongly diluted resorcinol-formaldehyde adhesive, which is applied before the actual adhesive. The effectiveness of HMR priming is proven for different wood species and adhesive types based on delamination tests and shear strength measurements. However, the primer is not used in the industrial mass production of glued laminated timber. The reason can be found in additional process steps, therefore costs, and the fact that certain combinations of currently broadly available wood species and adhesives yield proper bonds without the additional use of a primer. Nevertheless, due to ongoing changes in the availability of wood species, it becomes increasingly important to consider the use of currently less-used wood species, including the corresponding adaptations in the production process. Since it is known that the HMR primer improves the bond performance, but is not used due to necessary process changes, it would be interesting to integrate the primer's functionality into existing adhesive systems. This review summarizes and structures the available information on the HMR primer from previous research. Furthermore, that information is critically discussed and a model of functionality is introduced. Finally, it is evaluated if the existing knowledge about the HMR primer is sufficient to transfer its mode of action into existing adhesive systems or which questions need to be addressed to do so.