Journal Name: Holzforschung Volume: 75 Issue: 2 Pages: i-iii

In this paper, voxel-based finite element modelling based on spatial geometry and density data is applied to simulate the detailed stress and strain distribution in a large wood element. As example, a moulded wooden tube with a length of 3 m and a diameter of 0.3 m is examined. Gamma-ray computed tomography is used to obtain both, its actual geometric shape and spatial density distribution. Correlation

Microfibril angle (MFA) is a key biological trait contributing to wood stiffness, which is a common breeding objective for solid wood products in many tree species. To explore its genetic architecture, area-weighted MFA was measured in two Eucalyptus nitens progeny trials in Tasmania, Australia, with common open-pollinated families. Radial strips were extracted from 823 trees in 131 families and MFA

Oak heartwood usually darkens during and after drying. This darkening can be heterogeneous, leaving non-colored areas in the wood board. These light discolorations have been linked to heterogeneous distribution of tannins, but compelling evidence on the microscale is lacking. In this study Raman and fluorescence microscopy revealed precipitations of crystalline ellagic acid, especially in the ray cells

Alkaline delignification of wood tissue is the core of the global pulping technology and the most prominent large-scale separation of the main wood components. This work aims at improved understanding of the interplay between the topochemistry of alkaline pulping and the associated morphological changes. Morphology and chemical structure of partially soda-delignified wood chips were studied combining

This study aimed to investigate the antioxidant ability and the chemical composition of apolar and polar extractives from Douglas-fir bark, cork and phloem, establishing a possible correlation with the structural variation along the tree stem and geographic location. Douglas-fir bark extractives’ composition were analyzed at three stem heights in trees from two locations. Cork and phloem extracts’

This research work presents a modelling strategy to analyse thermal conversion rates of two thermal wood modification processes based on time-temperature superposition method. It gathers in a single study different original and bibliographic experimental works analysing the dry mass variation that occurs during thermal and hydro-thermal wood modification processes. The mass loss kinetic was successfully

This study proposes a new fractal model to improve the accuracy of equivalent thermal conductivity (ETC) prediction for wood and determine how the wood’s pore structure influences ETC. Using fractal theory and mercury injection porosimetry data, a fractal model for the geometry of the wood’s pore structure was built. The geometric model was then transformed into an equivalent thermal resistance model

The moisture-dependency of the fracture energy for unmodified and acetylated Scots pine (Pinus sylvestris L.) and birch (Betula pendula Roth) has been investigated. Specimens were conditioned at relative humidity levels of 20, 75, and 97%, as well as dry and water-saturated. At moisture contents below 15%, the fracture energy increased with increasing moisture content for both unmodified and acetylated

A lignin-based gel (AL-PE gel) was obtained from hardwood acetic acid lignin (AL) and poly(ethylene glycol) diglycidyl ether (PE) as a cross-linker at a high AL concentration, while the reaction at a lower AL concentration yielded an amphipathic derivative (am-AL-PE). The gel has been reported to swell in aqueous ethanol but shrink in pure water and ethanol. In the present work, swelling behaviors

Waterborne polyurethane resins (WPUs) were prepared from polytetramethylene ether glycol (PTMG) and PTMG/polyhydric alcohol liquefied lignin (LL) with isophorone diisocyanate (IPDI), and ethylenediamine (EDA) and 1,4-butanediol (1,4-BD) were used as chain extenders. The effects of LL and the kind of chain extender on the properties of the WPU suspensions and dried films were studied. WPU suspensions

The goal of the study was to analyze fracture properties of adhesive bond using a three-point end-notched flexure test and the compliance-based beam method. Critical strain energy release rates (GIIc) and cohesive laws were obtained for adhesive bonds made of European beech (Fagus sylvatica L.) and adhesives such as EPI, MUF, PRF and PUR. The experiments were assisted with FE analyses employing three

Journal Name: Holzforschung Volume: 75 Issue: 1 Pages: 101-103

Journal Name: Holzforschung Volume: 75 Issue: 1 Pages: i-iii

Plasma treatment is becoming a mature technique for modification of surfaces of various materials, including wood. A better insight in the treatment process and the impact of the plasma on properties of wood bulk are still needed. The study was performed on Norway spruce and common beech wood, as well as their thermally modified variations. The formations of the airborne discharge, as well as mass

As a natural graded material, bamboo has gradually increasing elastic modulus along the radial direction from the inner to the outer skin. Accurate measurement of the modulus distribution plays an important role in bamboo-based structural design. However, it is difficult to characterise this modulus distribution by using conventional testing approaches on bamboo slices. A more effective method was

In this study, an artificial neural network (ANN) model was designed to predict color change based on visual assessment of coated cross laminated timber (CLT) exposed outdoors. Coatings and stains were investigated based on ASTM protocols to assess wood surface visual rating, against checking, flaking, erosion, and mildew growth in the State of Mississippi (USA) during one year (2019–2020). It was

Erosion bacteria are the main degraders of archaeological wood excavated from waterlogged environments. Light microscopy and analytical pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) were exploited to study waterlogged archaeological wood (Pinus sylvestris L.) at different stages of bacterial decay. The research explored the biochemical changes related to erosion bacteria degradation

Natural bamboo is rapidly replacing wood, but it is highly hygroscopic and has poor dimensional stability. Herein, Moso bamboo was subjected to hygrothermal treatment at different temperatures. The hydrophobicity and dimensional stability of bamboo increased, as indicated by the 16.5% decrease in volumetric swelling and three-fold increase in the contact angle at 220 °C. The fibers and parenchyma cells

Identifying two anatomically similar species of Cupressaceae, Chamaecyparis obtusa and Thujopsis spp., is important to better understand the culture of wood use in Japan. However, the conventional method, which involves observing their cross-field pitting, cannot identify them in many cases. This study solves the above problem by introducing an anatomical criterion based on the micro fibril angle (MFA)

Treating wood with water-soluble resins is a well-known and effective method to improve the durability of wood. However, there has been no systematic work to date related to the influence of average molecular size of phenol-formaldehyde (PF) resin on the decay resistance of wood, especially of hardwoods. Therefore, the goal of this study was to investigate the effect of average molecular size of PF

This paper examines how the moisture conditioning method affects the electrical conductance of wood. A widely used dataset was acquired by Stamm in 1929 who used a method of conditioning where water-saturated wood specimens were partially dried, sealed and left for a period of time for moisture to be redistributed before the electrical conductance was measured. However, more recent measurements combined

Polyolefins used in building materials and furniture require the use of flame-retardant (FR) additives to improve their fire safety. Such additives should be safe to humans and the environment, and preferably bio-based. In the present work, the FR performance of unmodified and chemically modified technical lignins was compared to that of the ammonium polyphosphate/pentaerythritol (APP/PER) intumescent

This study applied synchrotron radiation XRD to analyze the mechanical behavior of cellulose microfibrils in wood containing annual rings (thickness: 5 mm), for different layers of the secondary cell wall, under uniaxial load. Cellulose in S2 and in S1 and S3 layers were analyzed respectively, and the data were used to investigate for deformation behavior in the lattice spacing (d004). As a result

The effectiveness of pressurized hot-water extraction conditions for obtaining galactoglucomannans (GGMs) from Pinus halepensis suitable for applications like coatings and films packaging was investigated. For this purpose, high molar masses with high yields are required, presenting a serious challenge for hot-water extraction processes. The extraction of GGMs was carried out in an accelerated solvent

Basic density is a fundamental wood property of pulp and sawn wood. An IML Resi PD 400 drilling resistance tool (IML System GmbH, Wiesloch, Germany) was used to evaluate the basic density of Eucalyptus nitens discs and the impact of needle friction on basic density prediction. To determine the accuracy of that prediction with the commonly used linear drill bit shaft friction correction and determine

A 3D combined elastic-plastic damage constitutive model for wood is proposed within the theoretical framework of classical plasticity and continuum damage mechanics (CDM). The model is able to describe the various behavior of wood under loading, including the orthotropic elasticity, strengths inequality under tension and compression in each orthotropic direction, ductile softening under longitudinal

With the growing popularity in digital systems and electronic communication equipment, there is an urgent need to develop lightweight, green, and efficient electromagnetic interference (EMI) shielding materials to handle the increasingly serious problem of radiation pollution. Herein, Ti3C2Tx (MXene)/natural wood (NW) composites were prepared using a vacuum-pulse impregnation method and characterized

The purpose of this study was to determine the applicability of methyl methacrylate (MMA) and MMA–styrene in treating batai (Paraserianthes falcataria) wood. The effectiveness of the treatment was evaluated based on Fourier transform infrared spectroscopy (FTIR) analysis, physico-mechanical properties of the treated wood, and moisture sorption isotherm using dynamic vapour sorption (DVS) apparatus

Although visible and near-infrared (Vis-NIR) spectroscopy can rapidly and nondestructively identify wood species, the conventional spectrometer approach relies on the aggregate light absorption due to the chemical composition of wood and light scattering originating from the physical structure of wood. Hence, much of the work in this area is still limited to further spectral pretreatments, such as

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

The establishment of agroforestry systems (AFS) is a consistent strategy to integrate sustainable supply of wood, food and environmental services in a single land plot. Teak (Tectona grandis Linn. F.) is an interesting option for the tree component in AFS, though there is a lack of information on its potential. This study aimed to characterize the quality of teak wood produced in an AFS regarding its

The moisture-induced recovery of compressed wood is one of the major problems of wood densification technology. Achieving a cost-efficient surface densification process without the need for additional resins to eliminate the set-recovery may lead to an increase in value of low-density wood species. A previous study has shown that a pre-treatment with ionic liquids (ILs) can nearly eliminate the set-recovery

In this work, a novel waterborne hyperbranched polyacrylate (HBPA) dispersed organo-montmorillonite (OMMT) emulsion was synthesized and used for the treatment of wood in a vacuum environment in order to enhance the physical and mechanical properties of the wood. The sapwood of Cathay poplar (Populus cathayana Rehd.) and Radiata pine (Pinus radiata D.Don) were used as the samples for experimentation

Mass loss (ML) of wood caused by thermal degradation is one of the most important features of the thermal treatments and referred to as an indicator of intensity and quality of the process. The ML is proportional to the quantity of the effective heat power exchanged during the treatment process, represented by the area of the temperature profile versus time during the process. In this paper a model

Journal Name: Holzforschung Volume: 74 Issue: 12 Pages: i-iii

Journal Name: Holzforschung Volume: 74 Issue: 11 Pages: i-iii

Moisture changes cause transient effects in various polymeric materials. In wood, they are mainly documented in semi-static or low-frequency domains and could explain various anomalies in wood behaviour, including the so-called mechano-sorptive effect. This article aimed at exploring and quantifying transient effects in wood vibrational properties, evidenced but in few publications. A series of 65

This article aims at providing a synthetic view of the equilibrium moisture content (EMC) dependence of wood vibrational properties (i.e. dynamic mechanical properties in the audio-frequency range), including specific dynamic modulus of elasticity (E′/γ) and damping coefficient expressing internal friction (tanδ). A series of multi-trajectories experiments was designed to complete an analytical review

Esterified phenolics occur as γ-linked lignin acylations in many plant taxa but little is known about the distribution or function of such groups. In the family Salicaceae, p-hydroxybenzoate groups are present in the lignin of poplars (Populus spp.) and willows (Salix spp.). In this study, the distribution of cell wall-bound p-hydroxybenzoate was examined in different tissue and cell types of poplar

Journal Name: Holzforschung Volume: 74 Issue: 10 Pages: i-iii

Lignin nanoparticles (LNPs) from lignocellulosic biomass are expected to become promising basic building blocks for various applications in the development of multifunctional nanocomposites. Facile green preparation of LNPs and their application in polyvinyl alcohol (PVA) composite films were studied in this paper. LNPs were produced by performing fractionation of wheat straws at less than 80 °C with

Young’s modulus in the longitudinal direction was measured by a longitudinal vibration (LV) test on western hemlock specimens with various length/width ratios. The effects of the configuration and orthotropy of the specimen on the measurement of Young’s modulus was investigated through subsequent finite element (FE) calculations. The experimental results suggested that Young’s modulus could not be

It is frequently observed that bamboo particle composites (BPCs) do not show higher mechanical performances than the corresponding wood particles composites (WPCs), although bulk bamboo is much stronger than wood in mechanical performances. Herein this phenomenon was demonstrated from the cell compositions in the applied bamboo particles. To address that, a simple method to physically separate bamboo

Journal Name: Holzforschung Volume: 74 Issue: 9 Pages: i-iii

The paper presents a novel approach to determine charring of wood exposed to standard and natural fire that is based on a new numerical model named PyCiF. The new model couples an advanced 2D heat-mass model with a pyrolysis model. A new charring criterion based on a physical phenomenon is implemented in the PyCiF model to determine charring of wood. This presents the main advantage of the new PyCiF

Samples of Scots pine sapwood were treated with epoxidized linseed and soybean oils to improve decay, insect and termite resistance of wood. Non-epoxidized (raw) linseed and soybean oils were included as reference treatment in the study. In the epoxidation process, hydrogen peroxide was used to open double bounds, and acetic acid was added as a catalyst. Two retention levels, Ret A (80–140 kg m−3)

Anisotropic shrinkage is a typically feature in wood, which is of critical importance in wood drying. In this study, the shrinkage strains over each growth ring were determined by a full-field strain measurement system during moisture content (MC) loss. Color maps were used to visualize the full-field distribution of displacement and shrinkage strain under different MC conditions. The variation of

The conformation of lignin in solvents is major key factors governing the physicochemical properties of aromatic polymers. However, the conformational changes of lignin in good and poor solvents is not clearly understood at the molecular level. In this study, short- (DP 2.77) and long-chain (DP 4.49) lignin oligomer model compounds composed solely of interunit β–O–4 bonds with a narrow polydispersity

This study aims at identifying the mechanisms of oil and water imbibition in heartwood and sapwood of Douglas-fir through a combination of original experiments with magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) relaxation measurements for oil and free water, and deformation measurements for bound water. Experiments by weighing are performed to verify whether the imbibition process

The objective of this work was to provide a rapid and nondestructive imaging method for evaluating the hygroscopic behavior of thermally modified lignocellulosic materials (softwood and hardwood). The difference in the hygroscopic behavior was explained by moisture content (MC) mapping results and molecular association characteristics of absorbed water (i.e. weakly, moderately, and strongly hydrogen-bonded

To improve the reactivity of lignin for incorporation into high value polymers, the introduction of amines via Mannich reaction is a commonly used strategy. During this functionalization reaction, intra- as well as intermolecular lignin–lignin crosslinking occurs, which can vastly change the elastic properties of the lignin, and therefore, the properties of the resulting polymer. Therefore, the molecular

Density of wood can be increased by filling its porous structure with polymers. Such densification processes aim to increase hardness of wood and are particularly interesting for flooring applications. This study aims to evaluate efficiency of different polymers for chemical densification based on the polymer properties. Yellow birch (Betula alleghaniensis Britt.) was chemically densified with seven

In this study, the effect of thermo-mechanical densification on the density, hardness, compression strength, bending strength (MOR), and modulus of elasticity (MOE) of fir and aspen wood pretreated with water repellents was analyzed. Wood specimens were impregnated with paraffin, linseed oil and styrene after pre-vacuum treatment. Then, the impregnated wood specimens were densified with compression

A combination of alkaline thermal pretreatment followed by thermomechanical extrusion was studied as a novel sequential pretreatment process for an effective breakdown of the lignocellulosic structure of Eucalyptus grandis wood (EW). The first step was studied by analysing the influence of two factors: the NaOH-to-dry biomass ratio or NaOH loading (NaOH/DM) and the liquid-to-solid ratio (L/S). Optimization

The effect of fungicidal components in wood has been known for ages, yet there is no method to assess the impact of such components on the durability of a wood species, as compared to other material characteristics that influence decay. In this paper, the importance of fungicidal effects on the natural durability of 10 wood species is assessed in relation to other decay-influencing factors with a new

An efficient separation technology for hydrolysates towards a full valorization of bamboo is still a tough challenge, especially regarding the lignin and lignin-carbohydrate complexes (LCCs). The present study aimed to develop a facile approach using organic solvent extraction for efficiently fractionating the main components of bamboo hydrolysates. The high-purity lignin with only a trace of carbohydrates

Numerous investigations on the antioxidant properties of different plant tissue extracts are available in literature, but few studies on the effect of thermally modified wood on secondary metabolites were carried out up to now. This study highlights the influence of the thermal modification of Castanea sativa Mill. wood on total content of antioxidant compounds and consequently on its antioxidant activity

The aim of this research was to explore the potential of acoustic impact test to evaluate the condition of hardwood logs in regard to internal decay, void, crack and defect ratio using an acoustic signal separation and enhancement algorithm. Longitudinal acoustic signals were obtained from 15 logs of four hardwood species through acoustic impact testing. The defect components were separated from the

This review compiles various literature studies on the environmental impacts associated with the processes of thermal modification of wood. In wood preservation field, the wood modification by heat is considered as an ecofriendly process due to the absence of any additional chemicals. However, it is challenging to find proper scientific and industrial data that support this aspect. There are still