Physical-Mechanical Properties of Wood Industrial Heat treated with Different Methods

Transcription

1 Physical-Mechanical Properties of Wood Industrial Heat treated with Different Methods Peter Niemz 1),Tamás Hofmann 2), Melanie Wetzig 1),Tamás Rétfalvi 2) 1) ETH Zurich, Institute for Building Materials; 2) University of West Hungary, Sopron

2 1 Introduction First publications by Stamm 1937 (USA) many publications a) Kollmann and Schneider 1963: Treatment in oxygen atmosphere b) Burmester 1973, 1975: FWD-method c) Giebler 1981: Treatment in autoclave with nitrogen atmosphere (since 2001 industrial application in Switzerland, Balz Holz AG) Since 1990: industrial application: Netherlands, France, Germany, Switzerland, Austria, Finland Production: ca m 3 / year (2010) 2

3 2 Aims of thermal modification Primary ideas: Increasing durability Increasing dimensional stability Derived ideas / partial main focus of selling: Colour changes Substitute for tropical wood (hardwood) Substitute for naturally aged wood (softwood) 3

4 3 Application fields of heat-treated wood Outdoor applications: Claddings, noise barriers, terrace floors, windows/doors Due to increased durability and dimensional stability Indoor applications: Parquet floors, furniture, substitute for naturally aged and tropical wood Due to colour changes and increased dimensional stability 4

5 Using of thermally treated spruce House produced from naturally thermally treated wood aged wood Chaletbau Matti/CH Balz Holz/CH 5

6 Using of thermally modified hardwood (for furniture) Thermally treated beech (Airport Zurich) Furniture:. Bikos/Germany) 6

7 Using of thermally treated wood for gladdings 7

8 4 Industrial thermal modification methods Vacuum-press-dewatering-method (Vacu 3 ) Treatment temperature devolves the wood samples using heating plates, (Timura, D), vacuum+ pressure (hot plates), T up to 240 o C, Pressure 80mbar Autoclave with steam atmosphere (Corbat, CH),T 170 o C Pressure 3bar Balz Holz AG Autoclave with inert gas atmosphere (nitrogen) (Balz, CH) pressure 7bar, T up to 170 o C Autoclave: 6m x 1,05m x 1,30m 8

9 Vacuum-press-dewatering-method (Vacu 3 ), Opel Therm (Timura/Germany) 9

10 5 Properties of heat-treated wood 5.1 Physical properties Colour changes untreated treated in autoclave (180 C) treated by Vacu 3 (195 C) Degree of colour change depends on the used modification process as well as the intensity 10

11 5 Properties of heat-treated wood 5.1 Physical properties Colour changes untreated heat-treated I heat-treated II BÄCHLE, SCHMUTZ (2006) Treatment intensity rises from heat-treated I to heat-treated II Counterbalanced differences between coloured and uncoloured heartwood 11

12 5 Properties of heat-treated wood 5.1 Physical properties None UV-stability Colour changes after 6 month natural weathering beech ash 12

13 5 Properties of heat-treated wood 5.1 Physical properties Equilibrium moisture content (EMC)* *in %, at 20 C and 65% relative humidity 13

14 Sorption velocity perpendicular to the grain S p, m and water diffusion resistance factor µ m to the grain (mean values) Dry- Cup beech ash, [m/s 0.5 ] [-] untreated method A method B untreated method A method B Wet- Cup beech ash untreated method A method B untreated method A method B

15 5 Properties of heat-treated wood 5.1 Physical properties Swelling beech ash 15

16 5 Properties of heat-treated wood 5.1 Physical properties Density 16

17 5 Properties of heat-treated wood 5.1 Physical properties Modulus of elasticity (MOE) 17

18 5 Properties of heat-treated wood 5.1 Physical properties Bending strength 18

19 5 Properties of heat-treated wood 5.1 Physical properties Brinell hardness 19

20 5 Properties of heat-treated wood 5.1 Physical properties Thermal conductivity λ 10 [W/(m*K)] Ash beech

21 Color

22 5 Properties of heat-treated wood 5.2 Structural properties Cracking fissuration into the cell walls ash untreated ash heat-treated by variant B 22

23 5 Properties of heat-treated wood 5.3 Chemical properties Total phenol content* HOFMANN, T. (2010) *in mmol quercetin/100g dry wood 23

24 5 Properties of heat-treated wood 5.3 Chemical properties Soluble carbohydrate content*, method A HOFMANN, T. (2010) *in mg glucose/g dry wood 24

25 5 Properties of heat-treated wood 5.3 Chemical properties *in mg /100g dry wood; reviewed by the flask method (40 C, 24h) 25 ROFFAEL, E.; KRAFT, R. (2010); ROFFAEL, E.; KRAFT, R., NIEMZ, P. (2008)

26 5.3 Chemical properties (Ash, treatment method A) Waste water - Main component analysis with GC-MS A Retention Time Compound name Area* ,3-butanedione Acetic acid methyl-butanal hydroxy- 2-propanone methoxy-2-propanone ,3-pentanedione Propionic acid hydroxy-2-butanone hydroxy-2-butanone Furfural (2-furanyl)-ethanone Butyrolactone ,5-hexanedione methyl-2(5H)-furanone methyl-furfural

27 5.3 Chemical properties (Ash, treatment method A) Waste water - Micro component analysis with GC-MS B oxo-pentanoic acid furancarboxylic acid methoxy-phenol Maltol ,2-benzenediol hydroxymethyl-furfural ,6-dimethoxy- phenol Vanillin hydroxy-benzeneethanol Acetovanillone (4-hydroxy-3-methoxyphenyl)-2-propanone Vanillic acid hydroxy-3,5-dimethoxy-benzaldehyde (4-hydroxy-3,5-dimethoxyphenyl)- ethanone hydroxy-2-methoxycinnamaldehyde hydroxy-3,5-dimethoxybenzoic acid ,5-dimethoxy-4-hydroxycinnamalde

28 5.3 Chemical properties (treatment method A) Waste water analysis with GC-MS 1: 1-hydroxy-2-propanone, 2: propionic acid, 3: 1-hydroxyde-2-butanone, 4: 1-(2-furanyl)-ethanone, 5: 4-oxo-pentanoic acid, 6: maltol, 7: 5-hydroxymethyl-furfural, 8: 4-hydroxy-4-trimethyl-cyclohexanemethanol, 9: 2,6-dimethoxy-phenol, 10: vanillin, 11: 4-hydroxy-benzeneethanol, 12: acetovanillone, 13: vanillic acid, 14: unknown component, 15: 4-hydroxy-3,5-dimethoxy-benzaldehyde, 16: 4-hydroxy-2-methoxycinnamaldehyde, Waste water from the treatment of Ash, Spruce 17: 4-hydroxy-3,5-dimethoxybenzoic acid, 18: 3,5-dimethoxy-4-hydroxycinnamaldehyde

29 5 Properties of heat-treated wood 5.4 Workability Characteristic offensive smell (depending from the method) Decreased water absorption (perpendicular to the grain direction) Partially higher pressing time by gluing (lower equilibrium moisture content and ph-value) Increased internal stresses when gluing treated and untreated wood together 29

30 6 Conclusion Colour changes depending on the process used and on the intensity of the treatment Physical-technological properties generally decreased with increasing heat-treatment intensity Changed chemical properties in consequence of heattreatment 30

31 Thank you for your attention 31