B.F. Yousif

The Effect Of Oil Palm Fibers As Reinforcement On Tribological Performance Of Polyester Composite

In the present work, the effect of oil palm fibers on tribological performance of polyester composite against a polished stainless steel counterface is investigated using a pin-on-disc machine. Wear and friction characteristics of oil palm fiber reinforced polyester (OPRP) composite and neat polyester were tested at different sliding distances (0–5 km), sliding velocities (1.7–3.9 m/s), and applied loads (30–70 N) under dry contact condition. SEM observations were performed on the worn surfaces to examine the damage features. The results showed that the test parameters significantly influenced the tribo-performance of OPRP composite and neat polyester. The presence of oil palm fiber in the polyester enhanced the wear property by about three to four times compared to neat polyester. In addition, the friction coefficient of OPRP composite was less by about 23% than that of the neat polyester. Wear mechanisms of OPRP composite were categorized by debonding, bending and tear of fibers, and high deformation in resinous region.

High-stress three-body abrasive wear of treated and untreated oil palm fibre-reinforced polyester composites

The aim of this study is to investigate the effect of treated and untreated oil palm fibres on high-stress three-body abrasive wear characteristics of polyester composites. Experimental tests were conducted at different applied loads (5–20 N) and two different rotational speeds (50 and 100 r/min) for 0.18 km sliding distance using a dry sand/steel wheel apparatus. The flow of the sand particles (560–900 μm) was 4.5 g/s. Morphologies of the worn surface of the composites were studied using a scanning electron microscope (SEM). Pull-out test was carried out to evaluate the interfacial adhesion characteristics of treated and untreated fibres. The results revealed that composites based on treated oil palm fibres exhibited better wear performance compared with untreated ones, i.e. the interfacial adhesion of treated fibres to the polyester was better than untreated fibres. Moreover, treated oil palm fibres were found to reduce the porosity of the composite, which in turn stabilized the surface tribo-characteristics. Based on the SEM analysis, the wear mechanisms were predominated by pitting, grooving, microcracking, microcutting, and fracture in the polyester region.

Frictional and wear performance of polyester composites based on coir fibres

Abstract This article presents an evaluation of frictional and wear performance of new polyester composites based on coir fibres. Coir fibre-reinforced polyester (CFRP) composites were developed in a multi-layer form, mainly in three and four layers. The influence of the coir fibres on the wear and frictional behaviour of polyester was evaluated using a block-on-disc (BOD) machine under dry sliding contact conditions against smooth stainless steel. Worn surfaces of the composites were observed using a scanning electron microscope. The friction coefficient and specific wear rate were presented as a function of sliding distance (0-4.2 km) at different applied loads (10-30 N). The results revealed that all test parameters have a very significant influence on the frictional and wear characteristics of the materials. Moreover, a higher coefficient of friction was exhibited in the four-layer composite. CFRP composites based on three layers exhibited better wear and frictional performance compared with the one with four layers and neat polyester. The wear mechanism was predominated by deformation and micro-ploughing in the resinous regions and debonding of fibres.

The effects of alkali treatment on the interfacial adhesion of bamboo fibres

In the present work, the potential of using bamboo fibres as reinforcement for polyester composites was evaluated. Two types of bamboo fibres were used: untreated and treated with different NaOH concentrations (1, 3, and 5wt%). Mechanical properties of both treated and untreated fibres were investigated. In addition, single-fibre pull-out tests were performed to study the interfacial shear strength of the fibres with the polyester matrix at different embedment length of fibres. Scanning electron microscopy was used to study the surface morphology of the fibres before and after the tests. Results revealed that an untreated fibre has the best strength and stiffness but lowest strain at break. An increase in alkali concentration reduces the strain at failure and ductility of bamboo fibres. However, the strength and stiffness of the fibres were increased. In addition, the interfacial shear strength was improved with longer embedment length and higher NaOH concentration.

Wear and frictional performance of betelnut fibre-reinforced polyester composite

Abstract The current work is an attempt to use betelnut fibres as reinforcement for tribo-polyester composite. The composite was fabricated using hand lay-up technique. It consists of 13 layers of randomly distributed betelnut fibre mats and 15 layers of polyester. Wear and frictional behaviours of the composite were studied against a polished stainless steel counterface using a newly developed block-on-disc machine. Tests were conducted at 2.8 m/s sliding velocity, different applied loads (5-30 N), and sliding distances (0-6.72 km). In addition, the orientation of the fibre mats, with respect to the sliding direction of the counterface, was considered, i.e. anti-parallel (AP-O), parallel (P-O), and normal (N-O). The worn surface morphology was studied using a scanning electron microscope. Optical microscopy was used to observe the wear track surface on the counterface. In addition, the modifications on the counterface roughness were studied. This work revealed that the presence of betelnut fibre in the matrix, namely P-O, enhanced the wear and frictional performance of the polyester by about 98 and 73 per cent. Applied load has less effect on the specific wear rate and friction coefficient of the composite, especially in P-O and AP-O. The composite behaved differently in N-O in which the wear and friction increased when the applied load and sliding distance increased. The composite exhibited higher wear performance in P-O compared with AP-O followed by N-O. In N-O, poor support of the fibres to the resinous was observed, i.e delamination, pullout, and breakage in the fibres. In AP-O, the wear mechanism was predominated by plastic deformation, micro- and macro-cracks in the resinous regions associated with pullout, and breakage of the fibre. In P-O, debonding of fibres was the main wear mechanism.

Wet adhesive wear characteristics of untreated oil palm fibre-reinforced polyester and treated oil palm fibre-reinforced polyester composites using the pin-on-disc and block-on-ring techniques

Abstract This article presents an investigation on the wear and friction characteristics of oil palm fibre-reinforced polyester (OPRP) composites sliding against a polished stainless steel counterface under wet contact conditions. Two different types of OPRP composites were fabricated, which were based on treated and untreated oil palm fibres (treated oil palm fibre-reinforced polyester (T-OPRP) and untreated oil palm fibre-reinforced polyester (UT-OPRP), respectively). The experiments were conducted using two different techniques, pin-on-disc (POD) and block-on-ring (BOR), integrated into the same tribo-machine. The tests were conducted at different rotational speeds (500 and 700 r/min) and 50 N applied load for different durations (10-60 min). The specific wear rate (Ws) and the friction coefficient were presented as a function of sliding distance. The morphology of the worn surfaces was observed using scanning electron microscopy (SEM) and the damage features were characterized. The results revealed that treating oil palm fibres has a significant effect on the wear and frictional performance of OPRP composites. Treating the oil palm fibres enhanced the wear properties of polyester by about 35-52 and 65-75 per cent in the case of the POD and BOR techniques, respectively. The observations on the worn surfaces showed various features of the damages such as debonding and breakage of fibres in the UT-OPRP composite.

Betelnut fibres as an alternative to glass fibres to reinforce thermoset composites: A comparative study

For the current work, investigations were carried out using treated betelnut fibre-reinforced polyester (T-BFRP) and chopped strand mat glass fibre-reinforced polyester (CSM-GFRP) composites. Results revealed that T-BFRP showed competitive performance of about 1.16%, 17.39% and 4.92% for tensile, flexural and compression tests as compared to the latter. Through tribological performance tests, T-BFRP composite showed superiority in wear for the dry and wet tests of about 98% and 90.8% while the friction coefficient was reduced by about 9.4% and 80% respectively. The interface temperature was lower by about 17% for T-BFRP composite subjected to dry test as compared to CSM-GFRP. SEM analysis revealed that the brittle effects observed on glass fibres during the tribo test enhanced the material removal rate which increased the thermo-mechanical effects at the rubbing zone. As such, evidence of adhesive to abrasive wear transition was observed when the CSM-GFRP composite was subjected to the stainless steel counterface. On the contrary, T-BFRP composite formed a thin layer of shield (i.e. back film transfer) on its worn surface during the test, which assisted in lowering the material removal rate.

Effects of fillers on the fracture behaviour of particulate polyester composites

In the current work, the fracture toughness of sand-particle- and wood-flake-reinforced polyester composites was studied under a linear elastic fracture mechanics approach. The effects of the particulate volume fraction (0–60 vol %) were studied. Scanning electron microscopy was used to observe the damage features on the composite surface. Results showed that sand-particle- and fine-wood-flake-reinforced polymer composites exhibited better results at 40 vol % than at other particulate volume fractions. Meanwhile, coarse-wood-flake-reinforced polymer composites showed higher properties at 30 vol % than at other particulate volume fractions. Observation of the composite surface after tests showed that sand particles have poor interfacial adhesion compared with wood flakes.

Mechanical and wear properties of oil palm and glass fibres reinforced polyester composites

In the current study, mechanical and tribological characteristics of neat polyester and its composites were evaluated. Polyester composites were based on either synthetic or natural fibres, i.e. chopped strand mat glass fibres reinforced polyester (CGRP) and oil palm fibres reinforced polyester (OPRP) composites. Abrasive wear behaviour of the selected materials was evaluated using Pin-on-Ring (POR) machine. The tests were conducted against different grads of SiC abrasive paper (400, 1000 and 1500G) and applied loads (5-20N) at constant rotational speed of 50rpm for 3 min duration. Scanning electron microscopy (SEM) was used to observe the fracture behaviour of tensile specimens and microstructure of abraded worn surfaces. As a result, oil palm fibres introduced better wear characteristics to polyester in compare to glass fibre. Meanwhile, it showed lower mechanical property than Chopped strand mat Glass fibre Reinforced Polyester (CGRP). For all composites, increasing the SiC paper grades decreases the weight loss while increasing applied loads increases the weight loss.

Tribological Characteristics of Sustainable Fiber-Reinforced Thermoplastic Composites under Wet Adhesive Wear

The friction and specific wear rate of sustainable kenaf fiber–reinforced polyurethane composites were investigated against stainless steel counterface and under wet contact conditions. The new composites were evaluated at different applied loads (50–80 N), sliding distances (up to 2.7 km), and fiber mat orientations. Scanning electron microscopy (SEM) was used to observe the damage features on the worn surfaces. The results revealed that sustainable kenaf fibers assisted in enhancing the wear and frictional performance of the polyurethane thermoplastic composite by about 59 and 90%, respectively. Operating parameters and mat orientation controlled the wear and the frictional behavior of the composite. Better wear performance was exhibited at high loads and when the fiber mats were oriented perpendicularly to the sliding direction. Observations of the worn surfaces revealed different features of damage such as microcracks, fiber tearing, fiber detachment, and delamination. However, there was no trace of fiber pull-out in any of the tested conditions.