Page 82 - Kutnar, Andreja, et al., eds., 2015. Proceedings of the 1st COST Action FP1307 International Conference - Life Cycle Assessment, EPDs, and modified wood. University of Primorska Press, Koper.
P. 82
density
decreased
from
685
kg/m3
to
620
kg/m3
(∆ρ
=
-‐9.3
%).
The
stiffness
of
beech
wood
along
the
grain
slightly
increased
after
the
thermal
treatment
(∆MOE
=
+
7.8
%),
more
significantly
for
the
most
dry
wood
samples,
where
MC
–
stiffness
relationship
remains
unchanged
(Fig.
1).
Oppositely,
a
slight
reduction
of
stiffness
of
beech
wood
after
thermal
treatment
was
confirmed
in
the
transverse
wood
direction,
most
significant
at
oven
dry
state
(∆MOE
=
-‐
15.7
%).
Figure
1:
The
relationship
between
wood
MC
and
MOE
of
innate-‐
(○)
and
thermal-‐treated
beech
wood
(●)
along-‐
(left)
and
transverse
to
the
grain
(right).
The
thermally-‐treated
beech
wood
retained
the
ultimate
strength
along
the
grain,
compared
to
untreated
wood.
Whereas
ultimate
strength
was
significantly
reduced
in
the
transverse
direction
(-‐41
%)
at
the
whole
examined
MC
interval.
The
relative
strength
(σ/σ0),
defined
as
a
ratio
of
ultimate
strength
at
a
single
MC
(σ)
and
at
oven
dry
state
(σ0),
confirmed
the
equality
of
strength
changes
with
wood
moistening
or
drying
in
both
groups
(C,
TT)
in
both
directions
(L,
T).
Figure
2:
The
relationship
between
wood
MC
and
σmax
of
innate-‐
(○)
and
thermal-‐treated
beech
wood
(●)
along-‐
(left)
and
transverse
to
the
grain
(right).
References
Boonstra,
M.
and
B.F.
Tjeerdsma
2006.
Chemical
analysis
of
heat-‐treated
softwoods.
Holz
als
Roh-‐
und
Werkstoff
64:
204-‐211.
Esteves,
B.M.
and
H.
Pereira
2009.
Wood
modification
by
heat
treatment:
A
review.
BioResources
4:
370-‐
404.
Ozyhar,
T.,
S.
Hering
and
P.
Niemz
2013.
Moisture-‐dependent
orthotropic
tension-‐compression
asymmetry
of
wood
Holzforschung
67:
395-‐404.
Poncsak,
S.,
D.
Kocaefe,
M.
Bouazara
and
A.
Pichette
2006.
Effect
of
high
temperature
treatment
on
the
mechanical
properties
of
birch
(Betula
papyrifera).
Wood
Science
and
Technology
40:
647-‐663.
Acknowledgments
The
authors
would
like
to
thank
to
the
Slovenian
Research
Agency
and
Ministry
of
agriculture,
forestry
and
food,
for
support
of
programme
P4-‐0015,
and
V4-‐1419.
Thanks
are
also
to
Evolen
company
(HR)
for
providing
timber
material
for
this
study.
70
decreased
from
685
kg/m3
to
620
kg/m3
(∆ρ
=
-‐9.3
%).
The
stiffness
of
beech
wood
along
the
grain
slightly
increased
after
the
thermal
treatment
(∆MOE
=
+
7.8
%),
more
significantly
for
the
most
dry
wood
samples,
where
MC
–
stiffness
relationship
remains
unchanged
(Fig.
1).
Oppositely,
a
slight
reduction
of
stiffness
of
beech
wood
after
thermal
treatment
was
confirmed
in
the
transverse
wood
direction,
most
significant
at
oven
dry
state
(∆MOE
=
-‐
15.7
%).
Figure
1:
The
relationship
between
wood
MC
and
MOE
of
innate-‐
(○)
and
thermal-‐treated
beech
wood
(●)
along-‐
(left)
and
transverse
to
the
grain
(right).
The
thermally-‐treated
beech
wood
retained
the
ultimate
strength
along
the
grain,
compared
to
untreated
wood.
Whereas
ultimate
strength
was
significantly
reduced
in
the
transverse
direction
(-‐41
%)
at
the
whole
examined
MC
interval.
The
relative
strength
(σ/σ0),
defined
as
a
ratio
of
ultimate
strength
at
a
single
MC
(σ)
and
at
oven
dry
state
(σ0),
confirmed
the
equality
of
strength
changes
with
wood
moistening
or
drying
in
both
groups
(C,
TT)
in
both
directions
(L,
T).
Figure
2:
The
relationship
between
wood
MC
and
σmax
of
innate-‐
(○)
and
thermal-‐treated
beech
wood
(●)
along-‐
(left)
and
transverse
to
the
grain
(right).
References
Boonstra,
M.
and
B.F.
Tjeerdsma
2006.
Chemical
analysis
of
heat-‐treated
softwoods.
Holz
als
Roh-‐
und
Werkstoff
64:
204-‐211.
Esteves,
B.M.
and
H.
Pereira
2009.
Wood
modification
by
heat
treatment:
A
review.
BioResources
4:
370-‐
404.
Ozyhar,
T.,
S.
Hering
and
P.
Niemz
2013.
Moisture-‐dependent
orthotropic
tension-‐compression
asymmetry
of
wood
Holzforschung
67:
395-‐404.
Poncsak,
S.,
D.
Kocaefe,
M.
Bouazara
and
A.
Pichette
2006.
Effect
of
high
temperature
treatment
on
the
mechanical
properties
of
birch
(Betula
papyrifera).
Wood
Science
and
Technology
40:
647-‐663.
Acknowledgments
The
authors
would
like
to
thank
to
the
Slovenian
Research
Agency
and
Ministry
of
agriculture,
forestry
and
food,
for
support
of
programme
P4-‐0015,
and
V4-‐1419.
Thanks
are
also
to
Evolen
company
(HR)
for
providing
timber
material
for
this
study.
70
