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To improve the resistance of wood to biological decay the Maillard reaction between introduced amines and wood cell-wall polymers can be utilised. However, initial studies in wood modification showed almost complete leaching of bicine and tricine from treated wood and the loss of beneficial effects. The objective of this study was to assess whether possible reactions of bicine or tricine with wood could be further enhanced and reaction products stabilised through the addition of glucose and/or citric acid. Thus, Scots pine sapwood specimens were impregnated with tricine or bicine, with or without glucose and citric acid, and then heated to a temperature of 160°C. The dimensional stability, degree of chemical leaching and mechanical properties were assessed. Overall, it was concluded that neither the presence of glucose nor citric acid did appear to enhance the reactivity of tricine or bicine. Anti-swelling efficiency (ASE) of 50% was observed for combined treatments of bicine/tricine and citric acid but the leaching resistance originated mainly from citric acid and glucose, with no indication for the retention of bicine or tricine. The presence of citric acid led to a strongly reduced modulus of rupture., Validerad;2024;Nivå 2;2024-08-15 (sofila);Full text license: CC BY-NC-ND License

Engineered wood products (EWPs) are being increasingly used as construction materials. EWPs are currently being made using synthetic adhesives or metal fasteners, which lead to poor recyclability and reusability. Therefore, this review paper focused on emerging adhesive- and metal-free assembling techniques including wood dowels, rotary-dowel welding, wooden nails, and dovetail joining as alternative ways of making prefabricated EWPs. This will contribute towards green construction and optimising the building process to minimise its negative impact on the environment and its inhabitants, while maximising the positive aspects of the finished structure. The respective advantages and shortcomings will be compared with those of equivalent EWPs. In general, the dowel-laminated timber (DLT) provides sufficient load-bearing capacity and even better ductility than EWPs of equivalent size, but its relatively low stiffness under a bending load limits its application as a structural element. Optimised manufacturing parameters such as dowel species, dowel spacing, dowel diameter, dowel insertion angle, dowel shape, etc. could be studied to improve the stiffness. The improved mechanical properties and tight fitting due to set-recovery of densified wood support its use as sustainable alternatives to hardwood dowels in DLT to overcome problems such as the loosening of connections over time and dimensional instability. The rotary welding technology could also enhance the strength and long-term performance of dowel-type joints, but its poor water resistance needs further investigation. The main obstacles to implementing DLT products in the market are missing technical information and design guidelines based on national codes., Validerad;2023;Nivå 2;2023-02-13 (hanlid);Funder: Republic of Slovenia; Slovenian Research Agency ARRS (J4-3087); CT WOOD, Luleå University of Technology

Guanyl-urea phosphate (GUP) was introduced into furfurylated wood in order to improve fire retardancy. Modified wood was produced via vacuum-pressure impregnation of the GUP–furfuryl alcohol (FA) aqueous solution, which was then polymerized at elevated temperature. The water leaching resistance of the treated wood was tested according to European standard EN 84, while the leached water was analyzed using ultra-performance liquid chromatography (UPLC) and inductively coupled plasma–sector field mass spectrometry (ICP-SFMS). This new type of furfurylated wood was further characterized in the laboratory by evaluating its morphology and elemental composition using optical microscopy and electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM-EDX). The chemical functionality was detected using infrared spectroscopy (FTIR), and the fire resistance was tested using cone calorimetry. The dimensional stability was evaluated in wet–dry soaking cycle tests, along with the mechanical properties, such as the Brinell hardness and bending strength. The fire retardancy of the modified furfurylated wood indicated that the flammability of wood can be depressed to some extent by introducing GUP. This was reflected in an observed reduction in heat release rate (HRR2) from 454.8 to 264.9 kW/m2, without a reduction in the material properties. In addition, this leaching-resistant furfurylated wood exhibited higher fire retardancy compared to conventional furfurylated wood. A potential method for producing fire-retardant treated furfurylated wood stable to water exposure has been suggested., Validerad;2022;Nivå 2;2022-05-02 (hanlid);Funder: CT WOOD, Luleå University of Technology; European Structural and Investment Fund, OP RDE (CZ.02.1.01/0.0/0.0/16_019/0000803);Part of special issue: Performance and Application of Novel Biocomposites II, Advanced Research Supporting the Forestry and Wood Processing Sector’s Adaptation to Global Change and the 4th Industrial Revolution

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. It was however observed that during the pre-treatment process the IL did not penetrate sufficiently deep into the wood to explain the achieved reduction in set-recovery. Based on these findings, the hypothesis was posed that further penetration of the IL into the wood occurs during the densification stage as a consequence of the applied heat and pressure. Thermo-gravimetric analysis (TGA) and gas-chromatography mass-selective-detection (GC-MSD) showed that the depth of penetration of the IL was greater after the densification process than before. Digital image correlation (DIC) showed that in regions with a high IL concentration, there was almost no set-recovery, and it gradually increased with a decrease in the IL concentration, as observed with TGA and GC-MSD analysis., Validerad;2021;Nivå 2;2021-06-18 (beamah);Forskningsfinansiärer: COST Action FP1407 ModWoodLife project; the Republic of Slovenia (investment funding of the Republic of Slovenia and the European Union’s European Regional Development Fund), the ARRS research project J4-1767

Wood modification (chemical, thermal, impregnation) represents an assortment of innovative processes continually being adoptedin the wood protection sector. COST Action FP1407 “Understanding wood modification through an integrated scientific andenvironmental impact approach — ModWoodLife” was initiated in 2015, with its 4-year programme aiming to investigate modificationprocessing and products design with emphasis on their environmental impacts. Among the final tasks within COST FP1407 wasto re-evaluate the current status of wood modification across the member countries. However, it became clear that activities in otherEuropean countries needed to be addressed, and as a result, a more extensive evaluation of wood modification processes across Europewas undertaken, as well as determining the activities globally. This paper outlines some of the recent updates in wood modification,along with summarising data collected by the authors from international colleagues and online sources, so providing an evaluationof the overall global position. These figures suggest that wood modification is undergoing a significant increase in production due todemand, with levels of recent growth seemingly suggesting this will continue for the coming years. Based on data gathered, the globalcommercial production of modified wood is dominated by thermal modification processes, which produce 1,110,000 m3/year. Amongthe other commercialised processes, acetylation accounts for 120,000 m3/year and furfurylation 45,000 m3/year. A further globalproduction of around 330,000 m3/year is estimated for other processes, predominantly based on resin-based systems (e.g., Impreg- andCompreg-based processes)., Godkänd;2021;Nivå 0;2021-02-05 (alebob);Finansiär: European COST Association, Swedish wood industry

Finansiär: COST Association

A wide variety of engineered wood products (EWPs) are currently available on the market, but many of these EWPs are still underutilized for reasons such as cost, poor dimensional stability, low durability etc. The market for new durable products of modified wood has increased substantially during the last few years. Wood modification is implemented to improve the intrinsic properties of wood, widen the range of timber applications, and to acquire the form and function desired by engineers, without affecting low environmental impact of the material. Today, the most frequently used wood modifications methods are thermal modification, furfurylation and acetylation of which thermal modification is dominant by volume, with an annual global production about 600,000 m 3 . To understand better how architects specify EWPs in their profession, a research project has been undertaken in Slovenia, Austria, France, Sweden, Croatia, Bosnia and Herzegovina (BiH). The results suggest that in general there is a positive perception regarding the use of EWPs in these countries. The study provides an updated overview of the perceived identity of modified wood products among architects. The perception of thermally modified timber is positive. Differences were found in the perception of EWPs, the importance of timber-based construction, and the markets for bio-based materials. Our findings suggest that as environmental attitudes evolve in society and a greater proportion of consumers search for environmentally friendly product alternatives, the opportunities for timber to gain higher market share will increase., Forskningsfinansiär: COST FP1407; Slovenian Research Agency (P4-0015)

Nowadays, a wide variety of engineered wood products (EWPs) are available on the market, but many of these EWPs are still underutilized. The market for new durable products of modified wood has increased substantially during the last few years. Wood modification is implemented to improve the intrinsic properties of wood and widen the range of timber applications, and to acquire the form and functionality desired by engineers, without jeopardizing the environmental friendliness of the material. To better understand this situation, a global research project has been undertaken in selected countries of Europe and selection regions in the United States to determine how architects specify EWPs in their profession. Results suggest that, generally, there is a positive perception regarding the use of wood in all countries. The study provides an updated overview of the perceived identity of modified wood products among the architects. The perception of thermally modified wood (TMW) is positive. Differences were found in perceptions of EWPs, the importance of timber-based construction and the markets bio based materials. Our findings suggest that as environmental attitudes evolve in society and a greater proportion of consumers search for environmentally friendly product alternatives, the opportunities for wood to gain market share will increase., ISBN för värdpublikation: 978-90-829466-1-1;Finansiär: COST FP1407; Slovenian Research Agency (P4-0015)

Wood modification (chemical, thermal, impregnation) represents an assortment of innovative processes currently being adopted in the wood protection sector. Though many aspects of these treatments are known, the fundamental influence of the process on product performance, the environment, and end of life scenarios remain relatively unknown. It is essential to integrate interactive assessment of process parameters, developed product properties, and environmental impacts. To optimise modification processing to minimise environmental impacts, much more information must be gathered about all process related factors affecting the environment (VOC, energy use, end of life use, etc.). To this end, COST Action FP1407 (Understanding wood modification through an integrated scientific and environmental impact approach - ModWoodLife) was initiated in 2015, with its 4-year programme aiming to investigate modification processing and products design with emphasis on their environmental impacts. This will require analysis of the whole value chain, from forest through processing, installation, in service, end of life, second/third life (cascading) and ultimately incineration with energy recovery.A recent task within COST FP1407 was to re-evaluate the current status of wood modification across the member countries, tasks previously undertaken within COST Actions E22 and E37 respectively and reported in several papers within several of the previous European Conferences on Wood Modification (ECWM). Whilst the early projected advances anticipated for various types of modified wood has not been as previously reported. During a COST FP1407 meeting in Florence, Italy, the national status of wood modifications in 18 different European countries was presented, and the findings will be presented herein., ISBN för värdpublikation: 978-90-829466-1-1;Finansiär: COST Association

Godkänd; 2015; 20150831 (dicsan)