Wood Processing WiSe 24/25 - PDF

Wood Processing WiSe 24/25 PD. Dr. Markus Euring Wood Technology and Wood-based Composites & Biotechnikum 1 Timetable Wood Processing WS 2024/25, Wed. 10-12 a.m. FSR 3.1...

Wood Processing WiSe 24/25 PD. Dr. Markus Euring Wood Technology and Wood-based Composites & Biotechnikum 1 Timetable Wood Processing WS 2024/25, Wed. 10-12 a.m. FSR 3.1 Date Tutor Topic Wed 23.10.2024 PD Dr. Euring Introduction & wood composition Wed 30.10.2024 Dr. Bollmus Wood anatomy Wed 06.11.2024 PD Dr. Euring Wood, water & energy Wed 13.11.2024 PD Dr. Euring Sawmilling lesson Wed 20.11.2024 Prof. Dr. Militz Solid wood products (construction, decorative, i.e. flooring etc) Wed 27.11.2024 Prof. Dr. Militz Wood preservation and modification - FSR 4.1 ! Wed 04.12.2024 Prof. Dr. Mai Paper production Wed 11.12.2024 PD Dr. Euring Fibreboards Wed 18.12.2024 PD Dr. Euring Particleboards Wed 08.01.2025 PD Dr. Euring Oriented strand boards (OSB) Wed 15.01.2025 PD Dr. Euring Veneer based products Wed 22.01.2025 PD Dr. Euring Wood Plastic Composites WPC Wed 29.01.2025 Prof. Dr. Mai Wood weathering and decaying Wood processing in the tropic countries and international cooperation on wood Wed 05.02.2025 PD Dr. Euring processing 2 Literature / Handbook of WOOD CHEMISTRY AND WOOD COMPOSITES, ed. Roger M. Rowell, Taylor & Francis 2005 / Science and Technology of Wood – Structure, Properties, Utilization (Tsoumis, G.), Publishing House Kessel / Wood – Chemistry, Ultrastructure, Reactions (Fengel, D. and Wegener, G.), De Gruyter / Shmulsky and Jones. - Forest Products and Wood Science: An Introduction (2011), Wiley Blackwell / Centenial edition: Wood Handbook: wood as an engineering material: https://www.fpl.fs.fed.us/documnts/fplgtr/fpl_gtr190.pdf / WOOD TECHNOLOGY ENGLISH TEXTBOOK glossary: https://is.muni.cz/th/gdxwb/Textbook_glossary_final.pdf / Principles of Wood Science and Technology. I Solid Wood. Authors: Kollmann, Franz F.P., Cote, Wilfred A.Jr. / R. B. Miller, Wood anatomy, McGraw-Hill Encyclopedia of Science & Technology, 9th ed., 2002 3  Materials from wood wood components: celuloza, lignin, ash?, hemiceluloza, resin?/ekstractives (water solable, solwate solable, polar, unpolar..) - tenini (znani pri vinu: ruber tree, evkaluptus, quercus (oak)). Lignin - izdelki, ki so še rjavi. Beli izdelki so bleached. 4 Packing materials 5 Construction materials wood concrete Asphalt 6 Other components from wood - for films For healthy: microcrystalline cellulose and derivatives 7 Cool wood 8 Beautiful wood 9 Modern wood 10 Wooden teeth 11 Environmentally, technologically and economically important… 12 13 Forest industries and their potential contribution to the national economy 14 Vegetation of the world 15 16 Forest types and distribution 17 Distribution of forests 18 wood as raw material is one of many global important trade products 19 Very useful raw materials 20  Consumption by Purpose http://www.homedepot.ca/eco-options/initiatives/wood-purchasing-policy/production-and- consumption 21 Global production and trade of forest products in 2020 http://www.fao.org/ 22 Wood as important raw material ~ 25 years ago… wood in 2022 reached approx. 4.000 50% million m³ The split is that 50% is used as fuel, 20% as paper/pulp and 30% as longer-lasting materials (wood products) in 2022: 4.100 in 2022: 1.881 in 2022: 400 23 Wood as important raw material 24 Wood frame house vs. buildings made of other materials 25 Comparing environmental impacts 26 Wood use and ecology The use of timber for structural purposes instead of steel or concrete results in a reduction of energy consumption and CO2-emissions 27 Wood use and ecology: LCA Life Cycle Assessment (LCA): In the case of a product, the life cycle embraces all activities that comprise extraction of raw materials, design, formulation, processing, manufacturing, packaging, use, (reuse), and disposal. 28 Wood use and ecology: GWP 29 Increasing wood supply 1. Increasing forest area 2. Installing plantations 3. Better yield by new sawing technology 4. Efficient use of waste 5. Better forest conditions 6. Longer use of products 7. Recycling (Cascade use) 8. Substitution: other sustainable resources 30 Plantations will contribute to an increasing share of the global supply! Projected potential industrial roundwood production (1995 -2050) (The global outlook for future wood supply from forest plantations, FAO 2000) 31 32 There is a big potential for residues... Globally some hundred millions of tons sawmill residues could be converted to wood composites or energy 33 Basic construction of wood 34 Chemical elements in wood Element % of dry weight Carbon 49 Oxygen 44 Hydrogen 6 Nitrogen slight amount Ash (Minerals)* 0.2 to 1.0 * remains of wood after complete combustion in the presence of abundant oxygen. Please note that we have chemical compositions and chemical elements 35 Essential parts of wood Wood Low(er) molecular substances macromolecular substances organic substances inorganic substances Polysaccharide Lignin Proteins a. o. (Holocellulose) 20-30% Cellulose Hemicellulose (Polyose) Extractives ~ 40% 20-30% 2-10% 90 -98 % 36 Main organic compounds of wood Average organic makeup of wood (% of oven-dry weight) * Cellulose Hemicellulose Lignin Extractives Hardwood 42 - 51 27 - 40 18 - 24 1 - 10 Softwood 42 - 49 25 - 30 25 - 30 2-9 Cellulose + Hemicellulose (+ some pectic substances) = Holocellulose * Data from: Holz Lexikon (2003); ISBN 3-87181-355-9 37 Where to find the components Cellulose Lignin Hemicellulose 38 General chemistry Sugar Starch Cellulose polymer polymer 6 C-atoms α-glycosidic bonds β-glycosidic bonds low solubility in water-soluble Unsoluble in water water 39 Carbohydrates (= Saccharides) carbohydrate is an organic compound comprising only carbon, hydrogen, and oxygen carbohydrates (saccharides) are divided into four chemical groupings: monosaccharides (sugar), disaccharides, oligosaccharides, and polysaccharides (cellulose, starch, chitin). 40 Cellulose -Made from anhydrous Glucose (C6H12O6) -molecular weight 50.000 to 500.000 -Linkage within the molecule, to neighboring molecules and to other (especially water) molecules by H-bridges -Annual production in a tropical plantation per tree: 5 kg -Biomass worldwide: 1.2 · 1017 g per year (0.6 · 1017 g Carbon) 41 H-bonds in cellulose Hydrogen bond β-1,4-Conjunction 42 Iα Iβ 43 Hemicellulose Basically consisting of different pentoses (mainly in hardwoods, e.g. xylose C5H10O5 ) and hexoses (mainly in softwoods, e.g. mannose C6H12O6 ) Soluble in a 17.5% solution of caustic soda (NaOH) Degree of polymerisation (DP) on the average about 200 44 Character of Hemicelluloses Structural substance of cellwall Polyose (Polysaccharide) Mixture of polysaccharides Short polymers (50 – 250) Responsable for swelling Spacer between cellulose molecules - mainly in early- and sapwood than in late and heartwood 45 Hemicelluloses in wood Polyose Softwood (%) Hardwood (%) Mannane (C6) 15–20 3–5 Xylane (C5) 5–10 20–30 Galactane (C6) 0.5–3 0.5–2 total 20–30 30–40 46 Lignin latin „lignum“ = wood stored secundarily (lignification!) 3-dimensional (not a uniform structure) amorphous pressure-resistant Lignin is the component that is not composed of carbohydrate (sugar) monomers 47 Lignin integral part of the cell walls the "glue" that holds everything together network structures the most abundant organic material on earth after cellulose -Very high molecular weight (5.000 – 10.000), -complex substance that has phenyl propane as a basic chemical unit (see box) -Primary function of lignin in wood is as a cross-linking and stiffening agent 48 Function of components Cellulose structure, elasticity, storage Hemicellulose structure Lignin structure, stability, waterproof, antibacterial Starch energy, storage Others protection, biocidal, attraction 49 Inorganic substances Element (mg/g) Ca Mg K Mn P Si Pinus banksiana 387 33.2 22.5 39.0 12.2 74.8 Pinus sylvestris 600 120.0 300.0 70.0 30.0 Picea abies 700 90.0 300.0 90.0 20.0 Tsuga heterophylla 421 25.3 79.0 19.0 9.2 46.7 Betula sp. 466 25.3 36.3 47.0 12.6 14.0 Populus sp. 257 90.9 79.3 4.5 9.5 Quercus rubra 366 52.0 60.8 14.9 15.6 50 Extractives in wood Alkaloide Morphine, caffeine, nicotine, cocaine Terpene Can be extracted by solvents (oils, rubber) Phenolic compounds (tannin) Starch 51 Extractives or accessory compounds Soluble in cold or hot water, alcohol, other solvents (or not at all) Waxes, oils, resins, fats, gums, tannins, and aromatic and coloring materials Minerals (ash) 0.3-1.0% (some tropical species up to 4%) Accessory compounds may cause problems in wood processing and use; but they could offer market niches 52 Some examples of problems caused by accessory compounds TEAK (Burma/Indonesia): … oily to the touch. Very durable but difficult to cut without carbide tipped saws. High silicate content makes it necessary to wipe surfaces with lacquer thinner before gluing. (from: http://www.mlwoodcutters.com/hardwoods.html) Many tropical hardwoods have silicate inclusions which cause rapid wear to mating shafts. (from: www.eng.warwick.ac.uk/DTU/pubs/wp/wp43/wp43.pdf ) Doussie (Afzelia bipendensis): It is rather difficult to saw and machine because of rapid dulling of saw teeth and cutters … Surfaces are difficult to stain where pores contain yellow deposits. …and it is difficult to glue. Wenge (Milettia laurentii): Sawing and machining are somewhat difficult because of rapid blunting of cutting edges. (Examples from Hapla/Mohr 2004: Identification and Description of selected Tropical timbers.) 53  Resins: problems and uses Resin is a more or less viscous liquid, composed mainly of volatile fluid terpenes, with lesser components of dissolved non- volatile solids which make resin thick and sticky Problems by sawing (paste over sawblade) Raw material for several purposes (terpentine, glue) Amber as jewelry 54 Rosin Rosin (=colophony) is the very viscous substance that's left over after all the more volatile substances are distilled from the resin (including terpentine). World production of rosin is estimated at 1.2 million tonnes per annum. Used to waterproof paper (30% of rosin production). Around 20% of the resins used in adhesives are derived from rosin. + Uses for the production of paints, linoleum etc. Source: http://www.worldwideflood.com/ark/pitch/pitch.htm 55 Gum arabicum prepared from an exudate (polysaccharide) of the stems and branches of sub-Saharan (Sahel zone) Acacia senegal and Acacia seyal (Leguminosae) trees tree produces large nodules during a process called gummosis to seal wounds in the bark Famers cut the bark and collect the gum (after 6 weeks) key ingredient in a variety of soft drinks, baking and confectionery items, dietary fibre products, lithography, cosmetics, pharmaceuticals and other industrial applications Source: http://www.acacia-world.net/html/sudan.html 56 Hydrosetting plastics as novel promising alternatives to replace current, non-sustainable plastics Lignin-based adhesives spruce Hydrosetting E beech J. Wang, et al. Kai Zhang,* Nature Sustainability, 2021, 4, 877. S. Singh et al. Kai Zhang*, Green Chemistry, 2022, 24, 2624 57