Bonding and bending performance of VTC wood composites

Transcription

1 Bonding and bending performance of VTC wood composites Milan Šernek University of Ljubljana, Slovenia Aleš Ugovšek, M SORA d.d., Slovenia Andreja Kutnar,, University of Primorska, Slovenia Frederick A. Kamke, Oregon State University,USA The International Conference on Wood Adhesives 2013 October 9 11, 2013, Toronto, Ontario, Canada 1/20

2 Outline of the presentation Liquefied Wood VTC Wood Experimental Material Methods Results Bonding performance Bending performance Conclusions 2/30

3 Slovenia on the map of Europe 3/30

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5 Department of Wood Science & Technology 40 employees 300 students 6 research groups 1. Wood anatomy and technology 2. Economics and organization 3. Wood machining 4. Wood chemistry 5. Wood pests and protection 6. Composites, adhesion and surface coatings 5/30

6 Innovative use of wood Wood residues Recovered wood Liquefied wood: Coatings Foams Adhesives 6/30

7 Liquefied Wood Product of thermochemical reaction Wood particles (sawdust or powder) Solvent/reagent (polyhydric alcohols) Catalyst (acid) 7/30

8 Liquefied Wood as an Adhesive Combination with synthetic adhesives UF, MF, MUF Synthesis of polymers epoxy, polyurethanes, polyesters Independent component 8/30

9 VTC Wood Densification of wood poor valuable wood species of low density Viscoelastic thermal compression (VTC) Kamke and Sizemore, 2008 VTC Wood High performance wood-based composites 9/30

10 Objectives To develop laminated wood composites VTC wood To determine the bond performance natural based adhesive (LW) synthetic adhesives (PF) To determine the bending performance MOE & MOR 10/30

11 Experimental Research collaboration Slovenia-USA: University of Ljubljana (UL) University of Primorska (UP) Oregon State University (OSU) Wood & adhesives (UP & UL) Liquefied wood (UL) VTC Wood (OSU) Bonding & bending performance (UP & UL) 11/30

12 Materials Low quality solid wood for VTC process: beech (Fagus sylvatica) spruce (Picea abies) Liquefied ed wood (LW) black poplar (Populus nigra) Phenol-formaldehyde (PF) adhesive Commercial plywood adhesive 12/30

13 Methods 1. VTC process 2. Wood liquefaction 3. Bonding of the specimens 4. Testing of the specimens: Shear strength / wood failure MOE & MOR 13/30

14 VTC process Pressurized vessel with hydraulic press: 1. Steaming 2. Venting 3. Compression 4. Cooling Wood species Specimen Density (g/cm 3 ) 500 mm x 240 mm 6 mm Spruce (S) (Picea abies) Beech (B) (Fagus sylvatica) A B C (control) A B C (control) /30

15 Wood liquefaction Wood (W): ethylene glycol (EG) = 1:3 + 3 % sulphuric acid 180 C 120 min Filtration Rotary evaporation W:EG= 1:1, 1200 kg/m 3 15/30

16 Bonding of the shear specimens Beech (B) and Spruce (S): Application rate = 200 g/m 2 T = 180 C p = 0.5 MPa Control (C) (6 mm): PF = 10 min LW = 18 min VTC wood (3 5 mm): PF = 6 min LW = 12 min 16/30

17 Bonding of the bending specimens Beech (B) and Spruce (S): Application rate = 200 g/m 2 T = 180 C p = 0.5 MPa Control (C): PF = 10 min LW = 18 min VTC & VTC + C: PF = 6 min LW = 12 min 17/30

18 Testing of the specimens Universal testing machine Zwick Z005 Shear strength test 4-point bending test 18/30

19 Results Wood densification Shear strength of adhesive bond Percentage of wood failure MOE MOR Failure types 19/30

20 Wood densification Characteristics of the control and VTC wood Specimen Initial thickness [mm] Initial density (D1) [g cm -3 ] Final density (D2) [g cm -3 ] Density increase 100*(D2-D1)/D1 [%] Beech B-control B-A B-B Spruce S-control S-A S-B /30

21 Shear strength of adhesive bond Beech 21/30

22 Shear strength of adhesive bond Spruce 22/30

23 Percentage of wood failure Specimen Wood failure (%) PF LW Spruce SC Spruce SA Spruce SB Beech BC Beech BA Beech BB /30

24 Wood failure & damaged surfaces 24/30

25 MOE of 3-layer composites 25/30

26 MOR of 3-layer composites 26/30

27 Failure types 27/30

28 Conclusions bonding performance Densification of beech and spruce wood did not significantly affect the shear strength of PF adhesive. Densification of beech significantly affect the shear strength of LW, but this was not evident for spruce. Shear strength th of all specimens bonded d with LW was lower than shear strength of specimens bonded with PF adhesive. Shear strength of beech specimens (PF & LW) was significantly higher than shear strength of spruce specimens. 28/38

29 Conclusions bending performance MOE and MOR of VTC wood increased compared to undensified control wood. Beech specimens attained higher MOE and MOR values compared to spruce specimens. Specimens bonded d with PF adhesive always exhibited higher h MOE and MOR than specimens bonded with LW. In the case of specimens bonded with PF adhesive, failures occurred in wood, while in the case of LW in the bondline. 29/30

30 Acknowledgements The Slovenian Research Agency through the: fundamental research project J Development of environmentally friendly adhesives from renewable plant polymers bilateral project BI-US/ Adhesive bonding of viscoelastic thermal compressed wood with environmentally friendly adhesives. Welcome to publish you research in the Journal of Adhesion Science and Technology (JAST). Thank you for your attention! ti 30/30