Tribo Performance of T-bfrp Composite Subjected to Dry/Wet Contact Conditions - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 301

fragmentation of fibers and removal of abrasive particles (El-Tayeb, 2008a). In anti-
parallel orientation, abrasive particles were moving through different interfaces alter-
nately, that is were more hindrance in the path of abrasive particles which constitutes
resistance and traps wear debris which in turn, reduces wear.
Contact conditions (dry/wet) have an equal important role which controls the tribo
performance of polymeric composites (Borruto et al., 1998; El-Tayeb, 2008b; Pothan
et al., 2003; Sınmazcelik and Yılmaz, 2007; Sumer et al., 2008; Wu and Cheng, 2006;
Yamamoto and Takashima, 2002; Yousif, 2008; Yu et al., 2008). It has been reported
that tribo performance of some polymeric composites were improved under wet con-
tact condition compared to dry (Wu and Cheng, 2006; Yamamoto and Takashima,
2002). It is known that increased interface temperature during adhesive dry loading
conditions caused high damaged on the composite surface during sliding especially
at the resinous regions due to thermo-mechanical loading conditions (Yousif and El-
Tayeb, 2010). As such, the cooling effect introduced by water prevents the pullout of
oil palm fibers from the polyester matrix as opposed to dry contact, that is wear is only
controlled by mechanical loading (Yousif and El-Tayeb, 2008b, 2010).
In previous work by the participating authors (Nirmal and Yousif, 2009; Yousif
et al., 2008), untreated betelnut fiber reinforced polyester (UT-BFRP) composite was
used to study the wear and frictional behavior of the composite under dry contact
condition. The work revealed that the average wear and friction coefficient of the
composite were reduced by 98 and 73% compared to neat polyester namely when the
fibers were oriented parallel to the sliding direction.
Thus, through the author's knowledge, there is no work reported on polymeric
composites based on treated betelnut fibers under dry and wet contact conditions.
Hence, the current work aims to study the effect of treated betelnut fibers on the tri-
bo-behavior of polyester composites. The interfacial adhesion strength of the treated
fiber with the polyester was determined using single fiber pullout test. The sliding
wear and frictional characteristics of the developed composite were evaluated using a
Block-On-Disc (BOD) machine under dry/wet contact conditions. The tests were con-
ducted at different applied loads (5-200 N) and sliding distances (0-6.71 km) against
a smooth stainless steel counter face with sliding velocity; 2.8 m/s.
materials PreParatioN
Preparation of Betelnut Fibers
The preparation of betelnut fibers was explained in a past publication done by the au-
thor (Nirmal and Yousif, 2009). The length and diameter of individual fiber were in the
range of 30-50 mm and 150-200 μm respectively. However, the prepared fibers were
soaked in a 6% Natrium Hydroxide (NaOH) solution mixed with tap water at tempera-
ture of 26 ± 5ºC for 48 hr. The fibers were rinsed and left to dry at room temperature
before being put in an oven for 5 hr at 45ºC.
One can see from Figures 1(a) and (b) that significant modifications occurred when
betelnut fiber was treated. Very rough fiber surface can be seen on the treated one,
Figure 1(b). Moreover, the trichome in Figure 1(b) seems to be rougher than in Figure
1(a). This could improve the interaction between the betelnut fibers with the polyester