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Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Dynamic Vapor Sorption Dynamic Vapor Sorption Analyses of Wood –A New Approach to Classical Problems
Prof.Dr.Rupert WimmerGeorg-August Universität Göttingen, Germany
SWST International Convention 2010, Geneva
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Relative humidity (%) Chemical formula Salt
12 LiCl Lithium chloride
23 CH3COOK Potassium acetate
33 MgCl2.6H20 Magnesium chloride
54 Mg(NO3)2.6H20 Magnesium nitrate
55 Na2Cr2O7 Sodium dichromate
44 K2CO3 Potassium carbonate
65 NaNO2 Sodium nitrite
75 NaCl Sodium chloride
79.5 NH4Cl Ammonium chloride
86 KCl Potassium chloride
93 KNO3 Potassium nitrate
97 K2Cr2O7 Potassium chromate
Salt solutions and the corresponding relative humidities used in sorption measurements at 20°C
Classical approach – salt solutions
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
DVS-Advantage
Water & SOLVENTSTemp: 5 - 60 CPre-heater: up to 350 C
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
DVS – mass change dynamics
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Basic isotherm studies
-5
0
5
10
15
20
25
30
0 20 40 60 80 100 120
Ch
an
ge
In M
as
s (
%)
-R
ef
Target % P/Po
DVS Isotherm Plot – pine
© Surface Measurement Systems Ltd UK 1996DVS - The Sorption Solution
Adsorption
Desorption
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Sorption isotherms and modeling
0
0,0005
0,001
0,0015
0,002
0,0025
0,003
0,0035
0,004
0,0045
0,005
0 0,1 0,2 0,3 0,4
n [
Mo
l/g
]
p/p0
BET Plot
experiment
subst. f it
0
0,002
0,004
0,006
0,008
0,01
0,012
0,014
0 0,2 0,4 0,6 0,8 1
n [
Mo
l/g
]
p/p0
Two-stage Freundlich Plot
experiment
f it
BrunauerEmmettTeller
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Sorption modeling
Hailwood-Horrobin modeling
hydrate - dissolved -monomolecular polymolecular
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Testing rare species
0
5
10
15
20
25
0 10 20 30 40 50 60 70 80 90 100
Ch
an
ge In
Ma
ss
(%
) -
Re
f
Target % P/Po© Surface Measurement Systems Ltd UK 1996DVS - The Sorption Solution
Balsa wood sorption isothermDensity: 80kg/m3
Adsorption
Desorption
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Fast-ramp study – never dried spruce
Opposite wood
Compression wood
Compression vs. opposite wood
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Particle board
temperature
p/p0=0%
weight response
Effects of temperature
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Diffusion-open fibreboards
Water and organic-vapor sorption
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Optimizing natural-fibre composites
compounded granules
-5
0
5
10
15
20
25
0 20 40 60 80 100 120
Ch
an
ge In
Ma
ss
(%) -
Re
f
Target % P/Po© Surface Measurement Systems Ltd UK 1996DVS - The Sorption Solution
Fasalex – wood, starch, resin
injection-molded sample
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Optimizing natural-fibre composites
0
1
2
3
4
5
6
20 30 40 50 60 70 80
Iso
the
rm H
ys
tere
sis
(%
)
Target % P/Po© Surface Measurement Systems Ltd UK 1996DVS - The Sorption Solution
Compounded granules
Injection-molded sample
Fasalex – wood, starch, resin
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Video-visualisation to evaulate dimensionallyadsorption-desorption processes
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Process technologies and sorption
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Process technologies and sorption
•water sorption•octane sorption as the next step(for „heat of sorption“)
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Video-visualisation to evaulate dimensionallyadsorption-desorption processes
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Wood
C2H5OH
Hemicelluloses
Chemicalsup to 24% d.m. Bioethanol
XylitolAdditives
Energynach Nutzung
Resination
Panel
Pressing
Pellets
Chips
Hot-water
extraction
Wood modification
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
0
2
4
6
8
10
12
14
16
18
0 10 20 30 40 50 60 70 80 90 100
Ch
an
ge In
Mass
(%) –
Ref
P/Po
Particle boards made from pre-extacted oak
© Surface Measurement Systems Ltd UK 1996-2009DVS - The Sorption Solution
4 h extraction
control
Wood modification
Wood Technology and Wood-based Composites
Georg-August-Universität Göttingen
Summary
• DVS pushes research in wood sorption
• easy to use and highly flexible
• For water and organic vapor
• Reliable data for modeling
• Software for advanced analyses
• Video and Sensor option for advancedwood physics