Environmental Engineering Reference
In-Depth Information
to voids in the i ber matrix interphase, which would apparently reduce the
mechanical properties of their composites. If moisture were not removed
from natural i bers prior to compounding by drying, the products would
become porous [23]. Also, absorption of moisture causes natural i bers to
be susceptible to rotting and to be less resistant to microbial attack [24],
yielding to poor i ber mechanical properties. h us, the high hygroscopic-
ity of natural i bers pose serious problems to their properties whether they
are being stored or are being processed. h e problems may also af ect their
composites' properties or their composite service life. In order to reduce
hygroscopicity, a number of studies were carried out to modify the hydro-
philic property of natural i bers. One of the successful treatments to reduce
hygroscopicity is by reacting the hydroxyl groups of natural i bers with
chemical reagents. Natural i bers can also be treated thermally by heating
the i ber and inducing chemical changes to its hydroxyl groups. As a result
of the reaction of chemical reagents or the damages to macromolecular
constituents at er heating, the treated hydroxyl groups become less ef ec-
tive in absorbing moisture compared to the untreated i ber.
Another new i ber treatment to be developed includes physical modii ca-
tion of the i ber in which the i ber is impregnated with thermosetting polymer
via a vacuum resin impregnation process. h is enhances the properties of
sugar palm i ber before it is used for composite reinforcement. h e principle
idea behind this process is to impregnate the i ber cell lumen and cell wall and
to enclose the i ber surface with hydrophobic thermosetting polymer in order
to prevent the absorption of water molecules to hydrophilic onto the i ber.
h e main objectives of this study were to compare the dif erences between
the two impregnation agents, phenol formaldehyde (PF) and unsaturated
polyester (UP), and to ascertain the ef ects of elevating impregnation pres-
sures on the physical and tensile properties of sugar palm i bers.
5.2 Experimental
5.2.1 Materials
5.2.1.1
Preparation of Fibers
Sugar palm (
Arenga pinnata
) i bers were from Kampung Kuala Jempol,
Negeri Sembilan, Malaysia. h e i bers were obtained from matured sugar
palm trees, aged more than 6 years and with a height of 20 m. For opti-
mum properties of sugar palm i bers [17], the i bers were obtained within
the live palm fronds. h e i bers were washed and air-dried for 24 h before
being dried in a Mermert oven at 80
°
C for 24 h. Phenol formaldehyde (PF)
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