50
4.5.5 Statistical Analysis 4.5.5.1 Statistical Analysis of poplar LVL
Density, MOE, MOR, Specific MOE SMOE and specific MOR SMOR were the observed parameters. The experimental results were statistically analysed
using an analysis of variance ANOVA to analyze the effects of veneer thickness 3 mm and 5.25 mm, poplar cultivars, juvenility juvenile and mature and
loading direction edgewise and flatwise. Mean differences between levels of
factors were determined using Duncan’s Multiple Range Test.
a
b c
Figure 27 Schematic diagram of destructive test for LVL from poplar cultivars and douglas-fir: four point bending test a; flatwise direction b; and
edgewise direction c
4.5.5.2 Statistical Analysis of douglas-fir LVL
Density, MOE and MOR were the observed parameters. The experimental results were statistically analysed using an analysis of variance ANOVA to
analyze the effects of veneer thickness 3 mm and 5.25 mm, juvenility juvenile and mature and loading direction edgewise and flatwise. Mean differences
between levels of factors were determined using Duncan’s Multiple Range Test
4.6 Results and Discussion for sengon and jabon LVL
4.6.1 LVL density
LVL density increased from pith to bark for LVL made of unboiled and boiled veneers of sengon and jabon Figure 28a-b. The average sengon LVL
density of unboiled and boiled type I were 370.1, 401.1, kgm
-3
respectively. Otherwise, the average sengon LVL unboiled and boiled type II were 391.4 and
408.1, respectively Figure 28a. The average jabon LVL densities were 473.7 kgm
-3
unboiled type I, 494.4 kgm
-3
boiled type I, 497.6 kgm
-3
unboiled type II, and 520.3 kgm
-3
boiled type II Figure 28b.
Load bending Load bending
51 A strong relationship between density of solid wood and of LVLs with
bending properties was observed by numerous authors Kilic et al. 2006; Shukla and Kamdem 2007
; H’ng et al. 2010. In general, LVL density of jabon had higher values than sengon. This fact was caused by the higher density of jabon
veneer compared to sengon veneers. The average veneer densities of sengon were 287.0 kgm
-3
unboiled sengon and 318.4 kgm
-3
boiled sengon. The average veneer densities of unboiled and boiled jabon were 395.3 and 406.9 kgm
-3
, respectively.
Figure 28 LVL density from pith to bark made of unboiled and boiled sengon a and jabon b veneers
4.6.2 Effect of lathe check on glue bond strength of LVL
The average glue bond strengths of the LVL increased from pith to bark for unboiled and boiled of sengon and jabon Figure 29a-b. The average glue bond
strength of unboiled and boiled sengon type I were 35.8, 38.2 kgcm
-2
, respectively. Otherwise the average glue bond strengths of unboiled and boiled sengon type II
were 39.8 and 43.1 kgcm
-2
, respectively Figure 29a. The average glue bond strengths of jabon LVL were 39.8 kgcm
-2
unboiled type I, 45.5 kgcm
-2
boiled type I, 43.2 kgcm
-2
unboiled type II and 50.7 kgcm
-2
boiled type II Figure 27b.
Figure 29 Glue bond strength of LVL from pith to bark made of unboiled and boiled sengon a and jabon b
300 350
400 450
500 550
600
1 2
3 4
5 6
7 8
L VL
d en
sity kg
m
-3
Segmented rings from pith to bark Unboiled sengon type I
Boiled sengon type I Unboiled sengon type II
Boiled sengon type II a
400 450
500 550
600
1 2
3 4
5 6
7 8
L VL
d en
sity kg
m
-3
Segmented rings from pith to bark Unboiled jabon type I
Boiled jabon type I Unboiled jabon type II
Boiled jabon type II
b
20 40
60 80
1 2
3 4
5 6
7 8
Glu e
bo nd
s tren
gth kg
cm
-2
Segmented rings from pith to bark Unboiled sengon type I
Boiled sengon type I Unboiled sengon type II
Boiled sengon type II
20 40
60 80
1 2
3 4
5 6
7 8
Glu e
bo nd
s tr
en gth
kg cm
-2
Segmented rings from pith to bark Unboiled jabon type I
Boiled jabon type I Unboiled jabon type II
Boiled jabon type II a
b
