treating wood improving durability by preservation & modification leonardo da vinci pilot...
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TREATING WOOD
Improving durability by preservation &
modification
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Treating wood
Wood preservation Wood modification
thermal treatment fire/flame retardant chemical modification
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Why do we treat wood ?
Natural restrictions of wood Durability
resistance against biological attack of fungi and insects
Shrinkage and swelling unequal swelling in greater dimensions
Degradation UV, mechanical, fire
Water adsorption and desorption
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
“Classical” Wood Preservation Mechanism toxicity Disadvantages:
emissions during production emissions during use emissions after use (waste stage)
New legislation (the Netherlands-Europe) Public image
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Alternatives to “classical” wp Durable tropical hardwood species
sustainable forest management (FSC) quality of plantation grown wood availability
Use of other materials pvc steel aluminium
Alternative treatment methods
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Wood preservation
Treatment methods
Vacuum - pressure Dipping, spraying Local treatment (pill, gasses)
Heating
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Foreco Dalfsen
Treatability of wood
Impregnation of wood wood anatomy and density fluids heat transfer
Reaction with the cell wall material structure of the cell wall chemical composition
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Treatability of wood
Impregnation of wood wood anatomy and density
surface penetration/treatment
deep or complete treatment
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
© SHR Hout Research
Treatability of wood Impregnation of wood - Classes
easy - complete penetration possible moderate - min. 6 mm after 2,5 hours of pressure hard - max. 3-4 mm after 3-4 hours of pressure very hard - after 3-4 hours of pressure hardly any
impregnation
Dependant on wood specie Sapwood & Heartwood
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Classical wood preservation
Tar oil - creosote Waterborne - metal salts (CCA) Organic solvent (PCP) Other
Local preservation
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Classical wood preservation
Aim improving the durability
increasing the resistance against biological attack fungi insects
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Modification of wood
More Aims Improving the durability
increasing the resistance against biological attack
Improving dimensional stability Aesthetic properties – Colour Hardness Water repellent Combination with flame retardant
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Modification of wood
Improving the properties of wood by means of changing the molecules of wood
No addition of toxic components
Alteration of low-value-wood-species
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Improved wood properties High durability (fungi, insects) Reduced shrinkage and swelling UV-stability Strength properties (both + and -)
LOWER MAINTENANCE
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Definition of modified wood Thermal treatment of wood:
chemical modification of the cell wall as a result of (hydro) thermal treatment
(Chemical) Modification of wood: when a true transformation of the chemical
structure of cell wall material
Alternative treatments of wood: non toxicity lumina filling (resin) treatments cell wall filling (resin) treatments true modification of the cell wall
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Levels of modified wood
Lumina filling resin treatments Cell wall filling resin treatments True modification of the cell wall
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Cell wall
Cell lumen
© SHR Hout Research
Mechanism of water uptake
cellulose
cellulose
OH
OH
OH
H
OH
OH
OH
H
OH
OH H
OOH
cellulose
cellulose
hydrogen bonds between two cellulose surfaces
hydrogen bonds between two cellulose surfaces and water
© SHR Hout Research
Resin treatments
Filling lumina no penetrationof cell wall
Bulkingpenetration of cell wall cavities
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
© SHR Hout Research
Modification the cell wall
Chemical alteration ofcell wall polymers
Substitution of OH-groups
Cross linking
Degradation of polymers (undesired)
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably © SHR Hout Research
Thermal modification of wood
Wood exposed to high temperatures for long period
Dry or hydro thermal treatment - one or several treatment steps
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Thermally modification wood
Distinguishing different thermally treatment processes
! excluding oxygen
nitrogen burning gasses steam (water damp) vacuum oil (vegetable oils)
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
A two steps process:1 hydro-thermolysis 165 °C - 185 °C
drying conventional2 curing 170 °C - 190 °C
1 2
Selectively reorganizing theSelectively reorganizing thechemistry of woodchemistry of wood
Cellulose
Hemicellulose
Lignin
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Water resistant
structure
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Cellulose
(hydro) Thermal treatmentexample: The Process Principle of the “Plato process”
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
© SHR Hout Research
Oil Heat treatment (Menz) Increased temperature 180-220oC
State of the Art Europe 2004 Processes
Plato (NL) Thermowood (SF) Perdure, NOW (F) Menz (D) AKBV (NL) Chalmers (S)
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
State of the Art Europe 2004 Commercial treatment plants:
Thermowood (> 10 production sites) Plato (1 production site)
Menz NOW, Perdure (producing) Acetylation plant (blue print)
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Challenges
Up-scaling: equipment / knowledge high costs
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Challenges
Commercialisation: co-operation chemical process industry and
wood industry high investments costs demand / availability price of process public image / acceptance
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
Utilisation of modified wood ?
Civil/waterworks Sheet piling Bridges Canal lining
Garden wood Sheds Fences Poles
Joinery Window frames Doors Cladding (Parquet) floors
(Garden) furniture
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably
More information The material in this presentation is partly delivered
by SHR (Centre for Timber Research), who are experts in wood modification and preservation in The Netherlands
For more information: www.shr.nl
Leonardo da Vinci’ Pilot Project, EURIS – Europeans Using Roundwood Innovatively & Sustainably