Adya Singh, Tatjana Smolic, Elizabeth Dunningham
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Transcript of Adya Singh, Tatjana Smolic, Elizabeth Dunningham
Ensis Wood Processing
THE JOINT FORCES OF CSIRO & SCION
THE JOINT FORCES OF CSIRO & SCION
Adding value to radiata pine wood: stiffness and dimensional stability enhancement by a novel process
Adya Singh, Tatjana Smolic, Elizabeth Dunningham
THE JOINT FORCES OF CSIRO & SCION
THE JOINT FORCES OF CSIRO & SCION
Introduction Pinus radiata , New Zealand’s
important natural resource But it lacks stability and stiffness
required in high value applications High performance applications
demand specific property improvements
THE JOINT FORCES OF CSIRO & SCION
Objectives
To enhance dimensional stability and stiffness
To launch high value product in the market
Possible applications: furniture, joineries...
THE JOINT FORCES OF CSIRO & SCION
Process development
A novel process developed to enhance stiffness through chemical treatment in combination with heat and compression
THE JOINT FORCES OF CSIRO & SCION
Materials and Methods
Rotary peeled veneer Dry sapwood Veneer samples conditioned at 20C and
50% RH
THE JOINT FORCES OF CSIRO & SCION
Zirconyl chloride treatment
30 min soak in ZrOCl2x8H20 solution Range of salt concentrations used
(0.01-3.5%)
THE JOINT FORCES OF CSIRO & SCION
Veneers saturated and radially pressed to 40% compression
Pressing temperature 130°C Pressing time 15 min
200mm
100mm
THE JOINT FORCES OF CSIRO & SCION
Weverk press
THE JOINT FORCES OF CSIRO & SCION
3 point bend test (before and after compression)
Tensile test (compressed samples only)
THE JOINT FORCES OF CSIRO & SCION
Veneer sample cut up for testing
HT1
HT2WS1
WS2
TT15mm
40mm
100 mm
THE JOINT FORCES OF CSIRO & SCION
Treated and compressed veneer was also tested
For dimensional stability (humidity cycling, and 24 hr water soak)
Surface hardness Microscopically and Chemically
HT1
HT2WS1
WS2
TT15mm
40mm
100 mm
THE JOINT FORCES OF CSIRO & SCION
Scanning Electron Microscopy
Control uncompressed Control compressed Zr treated compressed
THE JOINT FORCES OF CSIRO & SCION
Chemical testing
Zr content in treated veneer by ICP carbohydrate content (CHO) analysis NMR (not successful) SEM-EDAX (not successful) XPS (ESCA) (not successful)
THE JOINT FORCES OF CSIRO & SCION
Compression and thickness reduction
Target Solution Initial Compressed Compression Compress.
strength /%thickness/mmthickness/mm % %control 2.63 1.58 40 400.01 2.64 1.71 35 400.1 2.68 1.61 40 401 2.64 1.51 43 40
2.5 2.68 1.52 43 402.7 2.64 1.59 40 403 2.59 1.38 47 40
3.4 2.69 1.56 42 403.5 2.51 1.51 40 40
THE JOINT FORCES OF CSIRO & SCION
Changes in density
Solution Initial Compressed Density strength density density increase
% g/cm3 g/cm3 %control 0.401 0.621 550.01 0.390 0.594 520.1 0.371 0.600 621 0.389 0.622 60
2.5 0.441 0.712 612.7 0.395 0.631 603 0.371 0.601 62
3.4 0.416 0.659 583.5 0.437 0.656 50
THE JOINT FORCES OF CSIRO & SCION
Density before and after compression
Error bars represent one standard deviation
0
0.2
0.4
0.6
0.8
1
350.01
400.1
431
432.5
402.7
473
423.4
403.5
40control
Dens
ity (g
cm-3
)
not compressed compressed
Comp. Strain%Soln. Conc%
THE JOINT FORCES OF CSIRO & SCION
Properties of unmodified radiata pine
Radiata pine is a medium density softwood Dry timber (from 30 years old trees) has
average density of 453kgm-3 , MOE=8.23GPa and MOR=85.8MPa
THE JOINT FORCES OF CSIRO & SCION
Stiffness improvement Overall improvement by bend test
Solution initial MOE 3pt bendstrength MOE after compressonMOE increase
% Gpa Gpa %control 6.30 13.77 1190.01 5.37 13.55 1520.1 6.14 13.46 1191.0 6.08 14.72 1422.5 5.02 9.90 972.7 6.11 15.60 1553.0 7.70 17.77 1313.4 5.45 11.31 1083.5 7.15 11.28 58
THE JOINT FORCES OF CSIRO & SCION
Error bars represent one standard deviation
Specific stiffness of Zr treated compressed veneer
0
10
20
30
40
0.01 0.1 1 2.5 2.7 3 3.4 3.5
Soln conc.
MO
Es (G
pa)
Uncompressed Compressed
Modulus of Elasticity was normalised to specific value by dividing MOE with specific gravity
Stiffness improvement increased with increasing density
Salt concentrations did not increase stiffness
THE JOINT FORCES OF CSIRO & SCION
Stiffness and strength in tension
Solution bend tensile tensilestrength MOE MOE MOR
% Gpa Gpa Mpacontrol 12.5 13.24 53.55
0.1 11.09 12.66 50.261 15.25 17.52 47.02
2.5 10.15 13.09 19.762.7 13.56 12.60 25.283 19.24 14.24 33.24
3.5 14.88 13.56 24.71
Measured 12 months after initial MOE
THE JOINT FORCES OF CSIRO & SCION
Humidity cycling conditions
20°C& 65%RH 25 °C & 90-96%RH 25 °C & 30-40%RH Thickness recovery (spring back) measured
after humidity cycling
THE JOINT FORCES OF CSIRO & SCION
Thickness recovery after humidity cycling
21 2023
19
5
11
4 53
0
5
10
15
20
25
0 0.01 0.1 1 2.5 2.7 3 3.4 3.5
Soln conc.
Aver
age
thic
knes
s re
cove
ry%
THE JOINT FORCES OF CSIRO & SCION
Thickness recovery after 24 hours water soak
3128
3128
16 15 1411 12
0
5
10
15
20
25
30
35
0 0.01 0.1 1 2.5 2.7 3 3.4 3.5
Soln conc.
Aver
age
thic
knes
s re
cove
ry%
THE JOINT FORCES OF CSIRO & SCION
SEM images
Uncompressed veneer showing normal appearance of axial tracheids and rays and radial files of axial tracheids
THE JOINT FORCES OF CSIRO & SCION
Untreated compressed veneer showing considerable spring back of cells after water soak prior to block preparation (for microscopy)
THE JOINT FORCES OF CSIRO & SCION
3% ZrOCl2x8H2O treated and compressed veneer showing excellent compression retention after water soak prior to block preparation (for microscopy)
Note that compression extends throughout the entire thickness of veneer
THE JOINT FORCES OF CSIRO & SCION
3% ZrOCl2x8H2O treated and compressed veneer
The pattern of cell deformation is irregular, some cells are radially flattened but others deformed unevenly
THE JOINT FORCES OF CSIRO & SCION
3% ZrOCl2x8H2O treated and compressed veneer
Radial flattening of cells is evident in some parts
Cell walls are highly deformed but are largely intact with only minor cracks
THE JOINT FORCES OF CSIRO & SCION
3% ZrOCl2x8H2O treated and compressed veneer
Radial cell walls appear to be more deformed than tangential walls, with pit borders showing a range of deformities
THE JOINT FORCES OF CSIRO & SCION
Chemical analysis
Concentration of Zr in 3% ZrOCl2x8H2O treated and compressed veneer was 0.278% on oven dried weight basis measured by ICP
THE JOINT FORCES OF CSIRO & SCION
GC analysis of monosacharides
Sample Control Control Zr-chloride Zr-chloride SolidAverage % compressed replicate wood content (w/w) 3% 3%
Arabinose 1.44 1.53 1.27 1.01 1.44Xylose 6.3 6.1 5.9 5.7 4.8Mannose 12.2 13.3 11.8 9.2 12.1Galactose 1.7 1.6 1.6 5.3* 1.6Glucose 48.4 47.5 44 45.5 44.9Total 69.9 70 64.6 66.7 64.9
*could be compression wood
THE JOINT FORCES OF CSIRO & SCION
Surface Hardness test
1.351.12
1.04
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
ControlCompressed
Zr compressed Control
Dept
h of
pen
etra
tion/
mm
Error bars represent one standard deviation
THE JOINT FORCES OF CSIRO & SCION
Conclusions Compression fixation improved with an increase in
the concentration of Zr (particularly at 3% and above)
Stiffness increased up to 150 % Stiffness enhancement followed density increase No loss in cell wall components Mechanical damage to cell walls may have
contributed to strength losses Future developments to consider environmental
issues and specific product applications Potential for use of low grade radiata wood, e.g.
juvenile wood
THE JOINT FORCES OF CSIRO & SCION