Environmental Engineering Reference
In-Depth Information
40
PF
UP
PF: y = -2.2853x + 22.2
R
2
= 0.9989
UP: y = -1.088x + 26.205
R
2
= 0.9791
35
30
25.16 a
24.24 b
25
22.95 c
21.46 d
20.95 e
17.66 b
19.17 f
19.05 f
20
15.5 c
12.88 d
15
10.59 e
8.6 f
10
6.26 g
5
0
Control
1000
900
800
700
600
500
Impregnation pressure (mmHg)
Figure 5.12
Elongation at break of PF- and UP-impregnated sugar palm i bers at various
impregnation pressures.
lowest elongation at break for both i bers is at a pressure of 500 mmHg and
that the rate of reduction is more apparent in the i ber impregnated with PF
as seen by the slope in their regression trends. It is observed at a pressure
of 500 mmHg that the elongation at break of the i ber impregnated with
PF (6.26%) and UP (19.05%) was signii cantly dif erent. h is was a simi-
lar trend found with tensile modulus; no signii cant dif erence in elonga-
tion at break was observed between impregnation pressures of 600 mmHg
(19.17%) and 500 mmHg (19.05%). It was expected that the higher the
pressure, the more resin that would be absorbed into the i ber. h is was
proven by the increase in its WPG, resulting in the resin having more of an
inl uence on the i ber properties. h e improvement in strength and modu-
lus at er impregnation modii cation with resin has also been reported by
previous recearchers [30, 46, 47, 61, 25, 26]. It is seen in Figure 5.7 (stress
strain curve) that the impregnated i ber became brittle and had low elonga-
tion at break compared to the control sample (Fig. 5.12).
An important issue to be highlighted in this research is that while the
impregnated i bers increased in stress values, they showed signii cant
decreases in elongation at break, which may result in the reduction of
i ber toughness. Based on the area under the stress strain curve, the i ber
toughness can be measured to represent the total energy the material can
absorb before rupture. It is observed in Figure 5.13 that the toughness of
PF-impregnated i bers experiences a signii cant drop at high impregnation
pressure, as shown by the regression trend lines (with a slope of -4.2373
compared to -1.3385 for UP).
Statistically (p ≤ 0.05), no signii cant decrease in toughness was observed
for the i ber impregnated with UP compared to the control sample with an
increase in impregnation pressure. h is is because a material is known to
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