Wood modification is now widely recognized as offering enhanced properties of wood and overcoming issues such as dimensional instability and biodegradability which affect natural wood. Typical wood modification systems use chemical modification, impregnation modification or thermal modification, and these vary in the properties achieved. As control and understanding of the wood modification systems has progressed, further opportunities have arisen to add extra functionalities to the modified wood. These include UV stabilisation, fire retardancy, or enhanced suitability for paints and coatings. Thus, wood may become a multi-functional material through a series of modifications, treatments or reactions, to create a high-performance material with previously impossible properties. In this paper we review systems that combine the well-established wood modification procedures with secondary techniques or modifications to deliver emerging technologies with multi-functionality. The new applications targeted using this additional functionality are diverse and range from increased electrical conductivity, creation of sensors or responsive materials, improvement of wellbeing in the built environment, and enhanced fire and flame protection. We identified two parallel and connected themes: (1) the functionalisation of modified timber and (2) the modification of timber to provide (multi)-functionality. A wide range of nanotechnology concepts have been harnessed by this new generation of wood modifications and wood treatments. As this field is rapidly expanding, we also include within the review trends from current research in order to gauge the state of the art, and likely direction of travel of the industry.

The function of altering weathering factors and degradation mechanisms are essential for understanding the weathering process of materials. The goal of this work was to develop a method for the acceleration of natural weathering and to investigate the molecular, microstructure and macrostructure degradation of wood caused by the process. Tests were performed in the whole month of July, which, according to previous research, is considered as the most severe for weathering of wood micro-sections. Sample appearance was evaluated by colour measurement. Scanning electron microscopy was used for evaluation of the structural integrity and changes in the microstructure of wood morphological components. Changes on the molecular level were assessed by means of FT-IR spectroscopy. Observation of the effects of weathering allowed a better understanding of the degradation process. Typical structural damage, such as cracks on bordered pits and cross-field pits, and, as a consequence, their erosion, revealed the sequence of the degradation process. It was confirmed that earlywood was more susceptible to damage than latewood. Even if the weathering test was conducted for a relatively short time (28 days) the ultra-thin wood samples changed noticeably. The progress of alteration was similar as usually noticed for wood surfaces, but occurred at shorter exposure times. The estimated acceleration factor was ×3, compare to the natural weathering kinetics of wood. The research methodology presented can be used for the determination of the weather dose-response models essential to estimate the future service life performance of timber elements.

The present research aimed to assess the moisture properties and viscoelastic behaviour of artificially degraded pine wood, intended to serve as a model material for ongoing studies on new conservation treatments for waterlogged archaeological wood. Sorption isotherms and hydroxyl accessibility were measured using a Dynamic Vapour Sorption (DVS) system, while the investigation of the selected wood rheological properties was performed using Dynamic Mechanical Analysis (DMA). Fungal decomposition of pine by Coniophora puteana decreased the maximum equilibrium moisture content (EMC) from 20.3% to 17.7% in the first and from 19.9% to 17.1% in the second DVS run compared to undegraded pine, while chemical degradation using 50% NaOH solution increased the wood EMC to 24.6% in the first and 24.2% in the second run. The number of free hydroxyls measured for the biologically degraded sample was similar to sound wood, while chemical degradation reduced their number from 11.3 mmol g⁻¹ to 7.9 mmol g⁻¹. The alterations in the wood chemical composition due to different degradation processes translated into changes in viscoelastic behaviour. For biologically degraded wood, a reduction in the loss modulus and storage modulus at the temperature of 25 °C was observed compared to undegraded pine. Surprisingly, for chemically degraded pine, the values were more similar to sound wood due to the considerable densification of the material resulting from shrinkage during drying. The loss factor values for both degraded wood types were higher than for undegraded ones, indicating an increase in damping properties compared to sound pine. Distinct changes were visible in the storage modulus and loss factor graphs for DMA of chemically and biologically degraded pine. The degradation processes used in the study produced wood types with different moisture and viscoelastic properties. However, both seem useful as model materials in the research on the new conservation agents for waterlogged archaeological wood.

There is great interest in using bio-based materials to reduce the climate impact of materials. Similarly, there is an increased focus on the circular economy and recycling of materials to increase material efficiency and reduce waste. In the case of wood waste, this provides a cluster of benefits but has led to a high demand for the reclaimed material. This review provides updates on several technologies where wood fibre recycling and products from recycled wood fibre are breaking into new markets, including wood fibre insulation products, wood plastic composites, oriented strand boards, and fibreboards. Emerging technologies, such as the ability to recycle medium-density fibreboards, in addition to the more commonly recycled solid wood or particleboard, will allow for a new set of options within the wood cascading chain. Looking ahead, there are likely to be advances in new composite products, as well as other feedstock materials derived from reclaimed wood, such as nanocellulose, pyrolysis oils, or wood polymers reclaimed from the wood feedstock. This review arose from an investigation into the wood recycling sector in the UK. So, the horizon scanning exercise presented here considers the needs and challenges that may arise, if the volume of recycled wood fibre can be increased, in an already highly active market. Such developments would permit an increase in the manufacture of new-generation long-service-life products to enhance carbon storage, and potentially a shift away from bioenergy generation.

Welcome to the WIT Press eLibrary - the home of the Transactions of the Wessex Institute collection, providing on-line access to papers presented at the Institute's prestigious international conferences and from its State-of-the-Art in Science & Engineering publications.