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The effect of sanding, as the last operation before finishing, on the quality of heat treated wood surfaces has been insufficiently explored and explained. This paper compared the effects of sanding with three commonly used sanding grit sizes P60, P100, and P150 on the surface roughness values of beech (Fagus sylvatica L.) wood. The wood samples were treated by the ThermoWood process at 200 °C for 2.5 h. A large range of standard roughness parameters (Ra, Rq, Rv, Rt, RSm, Rsk, Rk, Rpk, and Rvk) and two waviness parameters (Wa, and Wt) were included in the analysis, as well as environmental scanning electron microscope (ESEM) images of the sanded surfaces. The results showed that the heat treatment slightly increased the surface roughness and decreased the wood surface waviness after sanding. All roughness and waviness parameters increased with increasing sanding mean grit diameters by following a strong linear correlation. The processing roughness was closely approximated by the parameter Rk. For both, treated and untreated beech, sanding had a tendency to obscure (in magnitude and number) wood anatomical details in the measured data. However, the influence of wood anatomy in the valleys domain increased as the grit size became finer.

Healthcare-associated infections (HAI) remain a burden in healthcare facilities, environmental surfaces being a potential reservoir for healthcare-associated pathogens. In this context, exploration of materials with potential antimicrobial activities represents a way forward for the future. Here, we explored the survival of four bacterial species commonly involved in HAI (Acinetobacter baumannii, Enterococcus faecalis, Klebsiella pneumoniae, Staphylococcus aureus), on oak versus three other materials (aluminum, polycarbonate, stainless steel). Twenty microliters of each bacterial suspension (approximatively 107 bacteria) were deposited on each material. Bacterial counts were measured by grinding and culturing on day 0, 1, 2, 6, 7 and 15. Analyses were performed in triplicate for each material and each time evaluated. It appeared that the bacteria viable count decreased rapidly on transversal and tangential oak compared with the other materials for all bacterial species. Furthermore, no difference was noticed between transversal and tangential oak. These results underline the potential for use of oak materials in healthcare facilities, a consideration that should be supported by further investigations.

International audience; Aim: To assess the activity of Quercus petraea (oak) on five bacterial species/genus frequently involved in hospital-acquired infections for evaluating the interest of going further in exploring the possibilities of using untreated wood as a material in the hospital setting. Materials & methods: We studied the activity of Q. petraea by the disk diffusion method. Results: Q. petraea was active on Staphylococcus aureus and Acinetobacter coalcoaceticus-baumannii complex, two bacterial species particularly resistant in the hospital environment, independently from their resistance to antibiotics, and was slightly active on Pseudomonas aeruginosa. Concurrently, Q. petraea was not active on Enterococci and Escherichia coli. Conclusion: Overall, untreated wood material presented antimicrobial properties that could have an impact on the cross-transmission of certain bacterial species in healthcare settings.

The present investigation aimed to utilize a direct wood disc diffusion method to study the influence of plane of cutting, cutting method, sterilization method, and origin of tree on the antimicrobial activity of wood material. Six oak wood trees (Quercus petraea) were collected from 3 different locations in France. They were cut into 4 mm thick slices with either transverse (RT), tangential (LT) or radial (LR) faces. Round discs (diameter 9.95 &plusmn, 0.1 mm) were cut from the slices via a laser machine or a manual punch machine, and were sterilized with gamma irradiation (25 kGy) or autoclaving (121 &deg, C). The antimicrobial activity of wood was tested using a direct diffusion method against Staphylococcus aureus and Acinetobacter baumannii isolates. The zone of inhibition around the wooden disc was recorded following the recommendations used for antibiotics tests. The results showed that S. aureus was more susceptible than A. baumannii, to the chemicals that diffused from the wood. The transverse face discs exhibited higher antimicrobial activity. Samples that had been sterilized by autoclaving showed significantly (p &lt, 0.05) lower antimicrobial activity, whereas the cutting method and origin of tree did not influence the antimicrobial activity of wood material. Therefore, the choice of sterilization method and cutting planes must be taken into account while studying and interpreting the antibacterial properties of wood material.

The weathering of wood through abiotic factors has been extensively studied. Much less research has been conducted on the influence of biotic factors on wood in exterior use that is not in ground contact, i.e. use class 3. There is especially a lack of research concerning the influence of the presence of bacterial and fungal communities on the weathering process of wood. The project aim is to identify any synergistic effects between biotic factors such as bacteria (Actinomycetes and Eubacteria) and fungi (Basidiomycota and Ascomycota) and abiotic factors such as light, temperature and moisture on the weathering of wood surfaces in use class 3. This paper presents results such as the amount of colony forming units (CFU), environmental scanning electron microscope analysis, colour changes and moisture content (MC) from preliminary experiments where wood surfaces were either naturally or artificially weathered. In order to study the interactions of fungi and bacteria on wood during the weathering process, the presence of microorganisms on natural weathered oak and Douglas fir surfaces had to be validated first. With the help of a surface contact test, microorganisms on the wood surfaces were transferred to agar plates and consequently incubated so that they could grow in appropriate conditions. Once the microbiological colonies had developed sufficiently, they were separated by selecting sections from the colonies and replated on fresh agar. A microcosm scale experiment, meaning the transfer of one specific bacteria and one fungi together in one petri dish, was carried out. This trial revealed that certain bacteria have an influence on the growth rate of certain fungi. In addition, an artificial weathering test was carried out in a QUV, which allows the degradation of samples using specific and known abiotic degrading parameters. The observation of the artificial weathered wood samples revealed that microorganisms are most definitely present in the QUV test apparatus and may influence the test results.

Although surface roughness can have a huge impact on finishing costs and the perceived quality of wood products, there is a lack of consensus on how to measure and evaluate wood surface roughness. One reason for this is that the presence of anatomical features can bias the measuring and evaluation of surface data. Consequently, the methods and recommendations given in general standards on measuring surface roughness do not apply well to wood surfaces. This review offers some recommendations on how to best measure and evaluate surface roughness. This review covers the measurement (instruments, methods, profile measurements versus area measurements, measuring length and resolution) and evaluation (form error removal, filtering, the selection of the cut-off length, removal of wood anatomy from the measured data, calculation of roughness parameters) of surface roughness of wood products. A set of best practices in order to overcome the biasing effect of wood anatomy is presented in this paper. Specific recommendations are given regarding the selection of the measuring instrument (stylus), the length of evaluation (at least 40 mm), the measuring resolution (5 μm), removal of form error (with or without prior removal of wood pores), the use of the Robust Gaussian Regression Filter, appropriate cut-off length (2.5 mm), the best roughness parameter for describing the processing roughness (Rk) as well as a method to separate the processing roughness from anatomical roughness by using an Abbot-curve. These findings, if automated in dedicated software can serve for optimisation of processing parameters in industry applications.

This paper is a study of checking and breakage of dry cereal products like crackers. The products studied were produced on an industrial line; almost no cracks were observed for Plain crackers (PCs), whereas 100% of the crackers with topping (CTs) exhibited cracks. Environmental SEM images suggested that miniature cracks initiated around the piercing holes of the crackers and then extended during storage.A study of the impact of each ingredient and of their interaction on the degree of starch gelatinization was carried out using a simplified model system (wheat flour, water and gradual enrichment until a model cracker dough was obtained). The addition of salt or sugar to flour at 40% water content shifted the starch gelatinization temperature slightly higher in comparison to a control mixture (only flour and 40% water content). A comparison of the residual gelatinization enthalpy between the PCs and the CTs made during storage (up to 3 weeks) showed that the degree of gelatinization of the CTs was more significant than the PCs (especially in the center) because of the presence of water in the topping in the center of the cracker. X-ray diffraction confirmed that the center of the CTs was indeed very different from the PCs.

International audience; Bedding material is an important requirement of floor-based poultry production systems to meet the health and welfare requirements. This substrate can be an organic material like wood or plant-based material or inorganic material like clay and sand and should generally be a good absorbant, easily available, comfortable and nontoxic to birds. Wood is an organic renewable resource having good humidity regulation and antimicrobial properties and its by-products are commonly used as poultry litter in many countries. For example, in France, wood-based bedding is used in 80% of turkey production. This litter has approximately 50% lower NH3 production compared to other materials like sand and hulls, and has multiple environment-friendly disposal options. Moreover, the birds grown on such litter show better health and welfare and they prefer to practice their natural behaviours on this material which is helpful for the amelioration of physiological status and reduction of locomotion injuries. Moreover, according to some studies, the birds show improvement in different performance parameters, for example, up to 5-7% improvement in daily weight gain, live body weight, feed conversion ratio (FCR) and survivability. These improvements may differ depending upon the production system and type of wood material used in experiments, still it can be concluded that wood-based bedding materials do not negatively affect the production potential of poultry. In addition, the antimicrobial potential of wood may help to counter the load of certain pathogens in environment of birds. This review describes the physiochemical properties of wood-based bedding materials and their role in production and welfare of poultry.

International audience; The objective of the present study was to develop a simple and direct screening method to assess antimicrobial activities of wood material. Wood samples consisted of sawdust and wood discs cut in transversal (RT) and tangential (LT) direction, from four different wood species which were tested against four important bacteria in hospital hygiene. Area of inhibition was observed around sawdust embedded wells and wooden discs placed on agar. This study showed that wood disc diffusion can be used to easily and rapidly screen antimicrobial properties of untreated wood, while sawdust diffusion needs further work to do this.

International audience; Wood recycling is common practice in most countries. Currently, recovered wood is used for relatively low value uses including energy generation, particleboard manufacture, animal beddings and landscape uses. This paper gives an overview of two research projects that aim to generate high-value products from recovered wood and thereby encourage even higher rates of wood recycling. One project is concerned with the extraction of nano-crystalline cellulose from waste MDF and the other produces laminated beams from recovered wood.

International audience; The design of wood-fiber based thermal insulating material with optimized properties and characteristics requires a good scientific knowledge of the latter. Currently, the technical, economic and ecological characteristics of a wood-fiber based composite mat are not well known. This article presents a methodology for the acquisition of expert knowledge so that the properties and characteristics can be modeled. The knowledge domain is multidisciplinary and it was delimited and decomposed into disciplines and domains of expertise. A panel of seven experts was constituted to cover the various disciplines and domains of expertise of the knowledge domain. Knowledge acquisition sessions, guided by the estimated importance and the availability of knowledge, were conducted using semi-structured interviews and the mapping of the existing causal relations between variables. A causal map was established to represent the causal knowledge of each of the experts and then, the established causal maps were assembled into a unique global causal map, which was subsequently validated by the experts. It contains the information necessary for formulating the properties and characteristics to be optimized, which were: thermal conductivity; thickness recovery of the material; the manufacturing cost and the product's environmental impact. Properties and characteristics are function of raw material type, their morphological properties and the manufacturing process variables. This methodology makes it possible to establish which objectives to optimize and which variables influence each objective. Consequently, the objective functions of the optimization problem can be clarified, specified and modeled.

International audience; The application of water-based finishes to wood surfaces is known to increase surface roughness by raising the grain. This phenomenon is detrimental in the appearance of the finished wood surface. To eliminate it, light denibbing is needed prior to applying the second coat of finish. The objective of this study is to optimize wood machining to minimize raised grain caused by water-based coatings and to avoid, or at least, to minimize the sanding operation between each coat of finish. Experiments were done on beech samples. Complete experimental design was defined to generate several surface qualities from \textquotedblleftsmooth\textquotedblright to \textquotedblleftrough\textquotedblright which are linked to the average thickness of the removed chips. The planing parameters were the cutting mode, cutting direction, feed speed, and rotation speed. To compare with existing practices in joinery industries, specimens were also sanded. Two layers of water based coating were applied. Half of the samples were sanded after the first coat and the other half were not. Following each coat, surface roughness was measured and raised grain was evaluated through tactile tests. Results show that sanding operation is responsible for more raised grain than planing. Whereas for planing, high chip removal thickness gives more raised grain after coating application. The effects of the other parameters on raised grain occurence are not found to be statistically significant. The average roughness (Sa), quadratic mean roughness (Sq), reduced peak height (Spk) and the material volume of the peak section (Vmp) are the roughness parameters best correlated with tactile evaluation of grain raising, but the correlations are weak.

This study investigates the potential of wood wastes, specifically post-consumer fiberboards, as a new source for cellulose nanocrystals (CNC). This underused resource has currently no commercially viable way to recycle it and so the volumes of fiberboard waste are growing rapidly. A sequential chemical fractionation was used to separate the three main constituents of wood, namely cellulose, hemicelluloses and lignin, and the non-wood components present in fiberboards, such as resins and finishes (e.g. varnishes, paints, plastics, laminates, etc.). Most of the non-cellulosic components and non-wood elements were removed by an alkali treatment followed by bleaching, resulting in a cellulosic fraction which is suitable for the further isolation of CNC by an acid hydrolysis step. The intermediate and final products were characterized by chemical composition, microscopic, spectroscopic and X-ray diffraction methods. The CNC obtained from wood waste are totally devoid of traces of contaminants and possess comparable characteristics and quality to those extracted from virgin wood fibers. The results indicate that fiberboard wastes can be used as promising alternative source for nanocelluloses production.

This study investigates the effects of fiber dimensions on hardboard properties. Fiber size is determined by the amount of energy applied during refining, and fiber size affects board properties; that is, production cost and board performance are closely related. Therefore, in the present paper, the effects of fiber dimensions on hardboard performance have been investigated. To optimize the hardboard process, fiber size was varied via screening, and the screen fractions were further classified using a Bauer-McNett apparatus. Hardboards were produced with mixtures of classified fibers. Bending strength, internal bond, and thickness swelling of the final boards were evaluated according to EN 310, EN 319, and EN 317, respectively. The effects of fiber size on the investigated properties were analyzed by means of multivariate linear regression. Generally, a higher proportion of small fibers appears to improve board performance presumably due to the higher specific surface area of fibers, which facilitate interfiber bonding.

The quality of a sanded wood surface is represented by its roughness, which can be separated from the originally measured data by a procedure of filtering. Past experience has shown that the robust Gaussian regression filter (RGRF) is suitable for wood surfaces because it does not introduce distortions into the roughness profiles. The filter works iteratively until a user-defined convergence condition is met. The iterations stop when the difference between two consecutive profile median values becomes smaller than a given tolerance. This paper examines the convergence of RGRF when applied to wood surfaces sanded with various grit sizes in order to establish the tolerance value, which leads to convergence with the minimum number of iterations. This study was based on monitoring the variation of roughness parameters with the number of iterations for a range of tolerance values. A tolerance of 0.01 μm was found acceptable for filtering sanded wood surfaces.

Results of tensile tests on “wet” and “dry” flax yarn are presented and these show the large effect that moisture content (MC) has on flax fiber modulus of elasticity (MOE). These results are compared to others from tensile tests on flax fiber reinforced epoxy unidirectional composites (FFREUC) made from “wet” and “dry” fiber. The homogenized fiber MOEs have been estimated for the composites using the inverse rule of mixture. Fiber MOE appears better for dry fiber (by around 20%) for both the yarn and composite. It is proposed that this difference is the result of changes to the quality of adhesion between matrix and fiber. Adhesion would appear to be better for wet fibers.

Three-layer polymeric diphenyl-methane-diisocyanate (pMDI)-bonded particleboards (PBs) were produced with different proportions of simulated recovered wood (rW) in the core layers (cLs) to assess the effect of rW on the formaldehyde (FA) release of PB. A pre-test was conducted on furniture and particle mixtures of rW to determine the range of expectable FA emission of rW. The FA content of the raw particle mixtures could be predicted from the contents of the individual raw material and did not change compared to the PB. FA content correlated strongly with PB-FA emission. It was possible to predict the maximum PB-FA contents, which should not be exceeded according to F**** and CARB 2 by linear regression models. At moderate and high total FA emission levels, the FA emission of the particle mixtures was approximately 60% higher than the emission of PB blocks. At low total FA level, the flask method and the gas analysis method exhibited different results with regard to the emissions from particles and their respective PBs.

This study evaluates the feasibility of incorporating reject fibres from paper recycling into wet process fibreboards as a partial replacement for virgin wood fibres. The rejects were obtained from newspaper and magazine paper recycling in the form of sludges. Three sludges were obtained from the process steps: coarse screening, fine screening, and flotation. Fibre size and inorganic contents of these fibres are presented. Incorporating rejects into a single layer panel has a negative impact on the visual appearance of the panels. Therefore, a method of making multi-layer fibreboards which permits the inclusion of rejects in the core layer was developed. The board performances were assessed according to EN 310, EN 317 and EN 319. The results indicate that the quantity of rejects incorporated into the panels must be limited. The maximum amount of the rejects, which do not significantly affect board performance, is estimated to be 10 %.

The aim of this work is to demonstrate that Fourier transform near infrared spectroscopy, with multivariate data analysis, can be used to distinguish between preservative treated wood and non-treated wood. This technique is quick, easy to use and has the potential to be non-destructive and portable. For this research, a set of calibration models for the elements boron, chromium, copper and cadmium and the organic preservative cypermethrin have been created using principal component analysis and soft independent modelling of class analogy. The actual metal contamination levels in the wood samples were determined by induction coupled plasma-atomic emission spectroscopy. It is shown that these models can be used to classify samples of wood on the basis of the presence of these chemical substances.

No recommendation was found in the literature with regard to which measuring resolution should be used when measuring wood surfaces and requirements in the general standard ISO 3274 (1996) appear too stringent. Due to its variability, wood requires longer evaluation length than recommended by ISO 4288 (1996) and combined with a high resolution will increase the matrix of data and so the time for scanning and data processing. A study was conducted on roughness profiles from sanded surfaces of oak, beech and spruce measured at different resolutions to see which is the lowest resolution that still allows accurate evaluation of the roughness parameters in real time. The effect of decreasing the resolution on roughness parameters was examined as compared with a resolution of 1 μm, which was taken as a reference. Results showed that a measuring resolution of 5 μm seems reliable for all species sanded with common grit sizes.

Wood products follow the same cycle as other materials: manufacture, use and disposal. For certain applications, chemical additives are added to wood to increase its durability against biological and physical attack. At the end of life, waste wood is chipped or crushed before being recovered as raw material for new products or as fuel for energy. In recycled wood, there is the potential that some wood particles are contaminated by hazardous substances, such as organic or heavy metal preservatives. Therefore there is a need for a quality control method of assessing recovered wood that is on the one hand sufficiently precise and on the other not too expensive to preclude the use of recycling wood in to new products. This paper covers some preliminary research that is part of a large study that aims to develop a robust analytical method for recovered wood. However the extreme variability of recovered wood makes it difficult to develop such protocols on real recovered wood samples. Consequently, model chip piles with known contamination levels were created to simulate real world recovered wood samples.

Wood-cement panels were manufactured using three lignocellulosic materials of Portuguese origin: blue gum (Eucalyptus globulus Labil.), maritime pine (Pinus pinaster Ait.) and cork (the bark of cork oak, Quercus suber L.). Portland cement was used as a binder in the ratio of either 8/1 or 4/1 (cement/lignocellulose on a weight basis). Experimental panels had a target density of 1500 kg/m3. Particles were used either as received or after water washing, or with the addition of CaCl2 as a setting accelerator. The following properties were determined: density, moisture content, thickness swelling, internal bond, modulus of elasticity and modulus of rupture. In general terms, the panels fulfill the requirements of the EN 634-1 and EN 634-2 standards. The only exception was the modulus of rupture which was lower than required. Unlike organic resin bonded panels, adding more binder does not necessarily result in better panels.

According to ISO 3274 form errors can be removed by fitting a polynomial regression through the original measured data called the total profile to obtain the primary profile. For wood surfaces it was found that the regression was affected by the presence of deep and grouped pores. To obtain a primary profile free of distortion, the deep pores can be removed from the total profile prior to applying the regression. A method was developed that eliminated the pores entirely. The efficacy of this method was tested visually and by comparing coefficients of determination r2 between the polynomial regression according to ISO 3274 (1996) and the total profile and the modified regression line when the effect of deep pores was removed and the modified profile that had no pores. The influence of the shape of the primary profile obtained by the standard method in ISO 3274 (1996) on further digital processing was tested on roughness profiles filtered with a Robust Gaussian Regression Filter. The undistorted primary profile was taken as a reference.

It is already known by the scientific and industrial communities that lignocellulosic substrates are, to a certain extent, inhibitors of the hydration reaction of cement. The extent to which and how they influence such reactions is still a matter of debate. Several techniques, such as calorimetry, i.e., the measurement of the heat evolved or obtaining temperature profiles during the hydration, the determination of extractive contents of lignocellulosic substrates and their relation with the characteristics of the hydration curves, or even testing of the mechanical properties of the wood-cement composites, have been used in previous research. This study complements past research using two techniques that have been used in the analysis of cement hydration but are not usually applied to lignocellulose-cement mixes, namely X-ray diffraction (XRD) and differential thermal analysis (DTA). The raw materials for this study were three lignocellulosic materials of Portuguese origin: cork (the bark of Quercus suber L.), blue gum (Eucalyptus globulus Labill.), and maritime pine (Pinus pinaster Ait); and Portland cement. The two techniques allowed tracking of the evolution of the main cement constituents during hydration. It was found that all the lignocellulosic substrates had detrimental effects on cement hydration. The blue gum exhibited the fastest hydration kinetics in the initial stage of reaction, but was then overtaken by cork, which at the end gave the highest hydration conversion amongst the three lignocellulosic substrates. Although pine caused the slowest initial hydration kinetics, with the passage of time its effect approached that of blue gum. At the end of the hydration period, specimens containing either species had similar quantities of hydration reaction products. The DTA and XRD results were consistent and are in good agreement with the temperature profiles and compatibility indexes reported in a previous work.

Data are presented on the effects that cork, blue gum, or maritime pine, all grown in Portugal, have on cement setting. These materials were mixed with cement either without any treatment or after being extracted previously with a range of solvents (ranging from nonpolar to very polar). Other experiments were carried out in which extractives or calcium chloride were added to the cement paste. All lignocellulosic substrates have detrimental effects on cement setting, which is mostly seen by a delay in attaining the maximum temperature in the process. However, the addition of calcium chloride was able to overcome this disadvantage. Extraction of the substrates with some polar extraction agents before addition to the cement paste only slightly improved compatibility, and the addition of water-based extractives to a cement paste affects the setting much less than the lignocellulosic material by itself. Several thermal compatibility indices, including a new index proposed in this article, were calculated from data taken from temperature profiles, and conclusions are presented on the performance of the setting systems, as compared with a neat cement paste. In addition, comments are expressed on the level of accuracy offered by the indices applied in this study, and how such accuracy can be checked or improved by matching them to the physical properties of the wood-cement composites.

Cork granules are produced as by-products and waste by the cork processing industries that make ‘bottle stoppers’ as a main product. These granules are of low density and could be used as lightweight aggregates for making concrete. This paper describes an investigation carried out to assess the compatibility of cork granules with cement for the manufacture of lightweight cementitious composites. Five different grades of cork granules varying in terms of size and density were investigated. The effects of extractives, particle size and density of the cork granules were studied. The results indicate that these parameters affect cement hydration in a complex way. At lower concentrations of cork (10%), only the extractives have an influence on hydration behaviour. At higher cork concentrations (20% and 30%), however, particle size and density also affect the compatibility. Nevertheless, cork granules are found to be compatible with cement.

Any quantitative evaluation of the roughness of a sanded surface requires that the data is filtered to remove form errors and waviness. The cut-off length of a roughness filter is the valuethat determines which wavelengths are to be removed from profile data. Wood surfaces contain irregularities due to both the sanding process and the anatomy. When this anatomical roughness is greater than the roughness due to processing, standard profile filters introduce distortions, which increase in magnitude when a short cut-off length is used. Wood anatomical irregularities overlaid on processing irregularities would render standard recommendation in selecting cut-off length unreliable.

Any quantitative evaluation of a sanded surface requires that the data be filtered to remove form errors and waviness. Wood surfaces contain irregularities due to both the sanding process and the anatomy, so the anatomical roughness must be excluded from any measurement of the surface if the processing roughness is to be properly evaluated. The efficacy of a number of standard filters was examined to see if they were suitable for oak, beech and spruce surfaces sanded with P1000 grit. Filters in current standards introduced distortions, but a robust Gaussian filter, contained in a draft standard, appeared to give roughness profiles free of distortions. The processing roughness and anatomical roughness, contained in the filtered profile, were separated with an algorithm based on a threshold defined in the material ratio curve. Work is continuing to compare the properties of different grit size and species combinations.

Chemically modified wood composites were obtained via the compression moulding of thermoplasticised Aspen (Populus tremula) sawdust. This sawdust was previously prepared by esterification with maleic anhydride (MA) and subsequent oligoesterification with maleic anhydride and glycidyl methacrylate (GMA). The thermoplastic properties of the chemically modified wood resulting from different modification procedures were confirmed and compared by compression-moulding experiments leading to preliminary and final products. An SEM study of the resulting products clearly showed that the oligoesterified wood had partially melted under pressure and temperature, such that the overlapping and surface melting of particles ensured adhesive bonding between those particles. A new type of wood/thermoplastic-wood composite was obtained. In these composites, the melted part of the modified wood plays the role of the cohesive matrix whilst none-melted wood remains as a fibrous reinforcing material. FTIR spectra suggested that changes in the chemical structure of the modified wood are possible during the thermal forming process (e.g. polymerisation of C=C double bonds).The final composites were yellowish-brown, glossy, plastic-like products that showed interesting physical, mechanical and biological properties. They are water-resistant and dimensionally stable and display good electrical insulating behaviour. Their mechanical properties (bending strength of ca. 64 MPa and tensile strength of ca. 36 MPa) are in the typical range for plastics and conventional wood-fibre/plastic composites, and are superior to common wood products such as fibreboards and particleboards. Furthermore, the outstandingly high internal bond (ca. 3.0 MPa) highlights the totally different adhesion mechanism operating in these new types of composites. Although the novel composites are much more resistant to decay than the original unmodified wood, they remain ultimately biodegradable plastic-like composites.

Summary The influence of wood upon the setting of cement is generally assessed by conducting semi-adiabatic hydration tests. The existing methods to quantify wood-cement compatibility are based on the maximum hydration temperature (Tmax ), the time (tmax ) to reach it or the heat evolved in a specified period. Results obtained by these methods at higher wood-cement ratios are not convincing and show inconsistencies for various reasons. This paper discusses these reasons and suggests an alternative method based on a maturity function. The results from the new calculation method are compared with those of the existing methods and demonstrate the superiority of this new method at higher wood-cement ratios.

The newly developed technique of wavelet transform enables us to observe the evolution in time of the frequency content of a signal. This property makes it very suitable for the detection of vibration transients. However, current algorithms for vibration analysis either have low resolution of features for detailed analysis in the frequency-band scale or are very time consuming. In this paper, we present fast wavelet-based algorithms for vibration analyses. The approximated Morlet wavelet is used to develop an infinite impulse response causal filter with the error kept at an acceptable level. Using this filter, the continuous wavelet transform (CWT) can be computed. The rapid computation of the CWT, together with autocorrelation enhancement, is developed for the detailed on-line vibration analysis. Thus, the raw vibration signal can be continuously processed and monitored, with warning or alarm signals being generated when pre-programmed levels are exceeded. Examples are used to illustrate the application of arbitrary fine frequency-band scale analysis and single specified central frequency in the time domain using the wavelet power spectrum, which enables small defect detection of bearings. Real-time condition monitoring, fault detection, tool wear monitoring, etc., which are related to vibration, can be achieved and implemented with the detailed analysis of vibration signals.

) was investigated for its solubility in water or aqueous NaOH, for its stability when stored in the form of a solution in 5% NaOH, and for the physical properties and bondability of formulations prepared by incorporation of tannins into a PF resin. The extract is poorly soluble even in aqueous NaOH and its reactivity towards formaldehyde increases with time when it is stored in the form of an alkaline solution. The incorporation of a solution of tannins made with 5% NaOH into PF resin did not affect adversely the physical properties of the resin. But also just the extract in 5% NaOH solution, when heated at 175 °C, develops strength comparable to the PF resin, as experienced with impregnated paper strips. Furthermore, these formulations develop bonds to wood and even a solution of just tannins presented a 100%-wood failure with the majority of the replicate samples, after bond strength tests.

The chemical composition of maritime pine (Pinus pinaster) bark and of alkaline bark extracts has been investigated with bark from trees grown in Portugal. Bark is composed of lignin and polyphenolics (ca. 44%), polysaccharides (ca. 39%), dichoromethane, ethanol and water extractives (ca. 17%) and ashes (ca. 1%). The lignin content determined by the Klason method, after the extraction of polyphenolics (tannin-rich fraction) from the bark by alkali solution, is 33.2%. Cellulose content is about 24%. Hemicelluloses (about 15% of bark dry weight) are suggested to be predominantly composed of arabinoglucuronoxylans and minor amounts of galactoglucomanans. The bark lignin is composed by p-hydrophenylpropane and guaiacylpropane units in proportions of 20:80. The condensed tannins are constituted mainly by catechin-type structural units. The direct extraction of bark with aqueous alkaline solutions yields extracts which contain sugars, lignin and condensed tannins. The number average molecular weights (Mn) of alkaline extracts are in the range 1000–1500. The composition and Mn of extracted substances depends on the alkaline extraction conditions.

Vibration signals are considered as nonstationary signals with transients. Conventional harmonic Fourier analysis finds it difficult to model the vibration signals. In this paper, a novel approach using the global Fourier transforms and local wavelet analysis is presented for vibration analysis and modelling. Time--frequency wavelet analysis has been proven a useful tool for the detection of vibration transients. However, current algorithms with discrete or continuous wavelet transforms for vibration analysis are either low resolution of features or very time consuming. We developed a fast Gaussian wavelet algorithm with very narrow band-pass filtering technique. The time-frequency maps with high frequency resolution enable us to observe the evolution in time of significant frequencies identified by global Fourier analysis, so that the transients and the regular signals can be distinguished. These regular significant frequencies are selected to be the basis of vibration modelling. The coefficients of the model are identified by a least-squares algorithm, which ensures that the error is minimised. To demonstrate this approach a machine spindle vibration signal is analysed, and the main features of the vibration signal are extracted, which are useful for system monitoring and further analysis.

Wood composites are made from various wood or ligno-cellulosic non-wood materials (shape and origin) that are bonded together using either natural bonding or synthetic resin (e.g. thermoplastic or duroplastic polymers), or organic- (e.g. plastics)/inorganic-binder (e.g. cement). This product mix ranges from panel products (e.g., plywood, particleboard, strandboard, or fiberboard) to engineered timber substitutes (e.g., laminated veneer lumber or structural composite lumber). These composites are used for a number of structural and nonstructural applications in product lines ranging from interior to exterior applications (e.g. furniture and architectural trim in buildings). Wood composite materials can be engineered to meet a range of specific properties. When wood materials and processing variables are properly selected, the result can provide high performance and reliable service. Laminated composites consist of wood veneers bonded with a resin-binder and fabricated with either parallel- (e.g. Laminated Veneer Lumber with higher performance properties parallel to grain) or cross-banded veneers (e.g. plywood, homogenous and with higher dimensional stability). Particle-, strand-, or fiberboard composites are normally classified by density (high, medium, low) and element size. Each is made with a dry woody element, except for fiberboard, which can be made by either dry or wet processes. Hybrid composites based on wood wool, particles, and floor mixed with cement or gypsum are used in construction proving high weathering and fire resistance in construction. The mixture with plastics (PP or PE) and wood floor open a new generation of injected or molded Wood Plastic Composites (WPC), which are able to substitute plastics for some utilizations. In addition, sandwich panels with light core made from plastic foams or honeycomb papers are used in the furniture industry.

Vibration signals from machining processes contain very useful information and offer excellent possibilities for in-process condition monitoring. Significant and natural frequencies in vibration signals reflect the inherent property of the system. Any change in the condition will result in the change in these frequencies. The time–frequency localization of the wavelet transform makes it very useful in signal processing, so that it can be used in filter design. In this paper, the wavelet filter with very narrow frequency-band and autocorrelation enhancement is proposed as a means of monitoring the natural frequencies in real-time. With the efficient, reliable and flexible wavelet filters, any number of natural frequencies in either the time or the frequency domain can be observed at the same time. After filtering, the signal with a single central frequency is enhanced by an autocorrelation algorithm in the time domain. This can provide real-time monitoring based on the changes of significant and natural frequencies, corresponding to the change in conditions.

Summary Aspen wood (Populus tremula) as sawdust was chemically modified through a two-step procedure: esterification with maleic anhydride and subsequent oligoesterification with glycidyl methacrylate and maleic anhydride. Chemical analyses and infra-red spectroscopy revealed the differences in the chemical composition and structure of wood as a result of this treatment. These changes were also reflected by a hygroscopicity test and thermal analyses such as thermogravimetry and thermomechanical analysis. The esterified wood showed an increased hygroscopicity and a decreased thermal stability compared to unmodified wood. In contrast, the oligoesterified wood demonstrated a reduced hygroscopicity and a comparable thermal stability up to about 200°C. The thermomechanical analysis of oligoesterified wood clearly showed a significant softening phenomenon in the range 80–140°C, a direct evidence of the thermoplastic properties gained by this chemical modification.

SummaryAspen wood (Populus tremula) as sawdust was chemically modified through a two-step procedure: esterification with maleic anhydride and subsequent oligoesterification with glycidyl methacrylate and maleic anhydride. Simplified techniques consisting of impregnation by immersion followed by thermal treatment using conventional or microwave heating were employed. Chemical analyses and infra-red spectroscopy showed some differences in the chemical composition and structure of the resulting oligoesterified wood depending on the synthesis technique. However, the thermoplastic properties, clearly revealed by thermomechanical analysis, were quite similar and comparable to those exhibited by the oligoesterified wood resultingviaclassical synthesis. Moreover, similar degrees of chemical modification were obtained for a significantly shorter duration of the process when microwave heating was employed instead of conventional heating.

Using wood in the French construction industry is not a fade but a real trend and this natural raw material is being used more frequently, especially in public or community buildings. As France has strict and demanding fire regulations, all construction materials, including wood, should comply with these rules (1). Even though wood is a very versatile and unique material, one of its weaknesses is poor fire reaction. This issue has to be solved for certain wood applications such as cladding. Effectiveness of treatment is well documented, however little information on fire reaction behaviour in real exterior conditions compared to artificial weathering can be found in the literature. An intensive and collective work has been published (2) (3) leading to a proposal of a new weathering procedure, that requires complex, newly design equipment (4) (5). Since this equipment is not readily available, this research uses techniques designed for testing finishes (6). The aim of this work is to investigate the applicability of these methods to basic boron and phosphorous-treated wood products and a new generation of products intended for exterior use.

Wood chips, mainly Sitka spruce (SS), were allowed to stand on a log yard for nearly 4 months. Samples of chips were taken at regular intervals during this period and their acidity and buffer capacity measured. The acidity of the wood was deter-mined by a method developed by Subramanian et al. (1983). This method is based on the reaction of wood acids with an aqueous solution of sodium acetate to liberate an equivalent amount of acetic acid. The amount of liberated acetic acid is measured by titration. This value is termed the ‘total acid con-tent’, as both bound and water soluble acids are extracted by the acetate solution. The buffer capacity of the wood chips was monitored using this method and it was found to change sys-temetically with storage. Changes in chip acidity may influence the curing process of urea formaldehyde (UF) resins. Therefore the age of the wood chips might be an important variable in chipboard and medium density fibreboard (MDF) production.

The use of scientific knowledge on waste wood management is the main factor that facilitates the responsible use of recovered wood respecting the environment. Nowadays, numerous scientific results are generated and published by universities and research institutions; but small quantities are exploited by nonscientific people. This problem is due to the difficulty of transfer and assimilation of this knowledge in its current representation. In this paper, we propose a new structure and representation of both type of scientific knowledge (declarative and procedural) to facilitate its transfer to non-scientific people through a hypertext electronic knowledge-book. The declarative scientific knowledge has been represented by concept maps and hierarchically structured through semantic relationships and the procedural scientific knowledge has been represented by technical sheets.