Wood Research Centre

Roger E. HERNÁNDEZ

IUFRO Division 5 Conference

5.04.06 Wood Drying

Wood Research Centre2

Department of Wood and Forest Sciences, Laval University, Quebec (Qc), Canada G1K 7P4

Effect of temperature on changes in physical properties of wood below and above the fiber saturation point

Roger HERNÁNDEZ*

and Zaira SILVA

Slovakia

European Union

Quebec

Wood Research Centre

Aim of work and methods

3

To study the effect of the equilibrium moisture content (EMC) on wood properties below and above the fiber saturation point (FSP) for two hardwoods at two temperatures

Desorption experiments using two experimental techniques Evaluation of EMC, shrinkage, FSP, and compression stiffness

in tangential direction

Wood Research Centre

Results

4

EMC-WP relationship of yellow EMC-WP relationship of yellow birch and beech at 25°Cbirch and beech at 25°C.

Shrinkage-EMC relationship of Shrinkage-EMC relationship of yellow birch at 25°Cyellow birch at 25°C

0

20

40

60

80

100

120

Water potential (J / kg-1)EM

C (

%)

Yellow birch

Beech

-106 -105 -104 -103 -102 -101 -100

Relative humidity (%)

0.07 48.36 92.99 99.28 99.93 99.99 100

0

2

4

6

8

10

0 20 40 60 80 100 120EMC (%)

Woo

d sh

rink

age

(%)

VolumetricTangentialRadialPSF

Yellow birch at 25°C

Wood Research Centre

At equilibrium, wood shrinkage begins well At equilibrium, wood shrinkage begins well above the fiber saturation pointabove the fiber saturation point.

The EMC affects Young’s modulus in The EMC affects Young’s modulus in tangential direction well above the FSPtangential direction well above the FSP;

A region hence exists where the loss of A region hence exists where the loss of bound water takes place in the presence of bound water takes place in the presence of liquid waterliquid water.

Conclusions

.