Dynamic Vapor Sorption Analyses of Wood A New Approach to

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

[email protected]

SWST International Convention 2010, Geneva



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



DVS-Advantage

Water & SOLVENTSTemp: 5 - 60 CPre-heater: up to 350 C



DVS – mass change dynamics



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



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



Sorption modeling

Hailwood-Horrobin modeling

hydrate - dissolved -monomolecular polymolecular



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



Fast-ramp study – never dried spruce

Opposite wood

Compression wood

Compression vs. opposite wood



Particle board

temperature

p/p0=0%

weight response

Effects of temperature



Diffusion-open fibreboards

Water and organic-vapor sorption



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


Fasalex – wood, starch, resin

injection-molded sample



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

(%

)


Compounded granules

Injection-molded sample

Fasalex – wood, starch, resin



Video-visualisation to evaulate dimensionallyadsorption-desorption processes



Process technologies and sorption



Process technologies and sorption

•water sorption•octane sorption as the next step(for „heat of sorption“)



Video-visualisation to evaulate dimensionallyadsorption-desorption processes



Wood

C2H5OH

Hemicelluloses

Chemicalsup to 24% d.m. Bioethanol

XylitolAdditives

Energynach Nutzung

Resination

Panel

Pressing

Pellets

Chips

Hot-water

extraction

Wood modification



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



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

Dynamic Vapor Sorption Analyses of Wood A New Approach to

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