Mohd Zulkefli Selamat

Effect of Carbon Nanotubes on Properties of Graphite/Carbon Black/Polypropylene Nanocomposites

High chemical corrosion, low manufacturing cost and light of total mass of bipolar plate in Proton Exchange Membrane Fuel Cell (PEMFC) lead most of the PEMFCs researchers over the world attracted their interest to replace pure graphite or metal based bipolar plate with conductive polymer composites (CPCs) bipolar plate. CPCs is fabricate from the mixed of conductive fillers such as and Graphite (G) andCarbon Black (CB) had been incorporated in Polypropylene (PP) matrix for fabrication of electrical conductive polymer composite plate. Most researchers reported only at high loading of fillers (more than 90 wt.%), are gave electrical conductivity above 100 S/cm, which is target from Department of Energy (USA). Higher loading of fillers cause change in rheological properties and increase the difficulties in polymer processing. Thus will decreasing the electrical and mechanical properties of CPCs as bipolar plate. Therefore, in this study carbon nanotubes (CNTs) which have 1000 time electrical conductivity than copper wire are introduced into G/CB/PP composite to compensate above problems. But the main problems of CNTs, at high loading it tend to agglomerate and thus will affect the properties of CPCs. So that, small amount of CNTs which is 0.2, 0.4, 0.6 and 0.8 wt.% will be added into G/CB/PP composite. But weight percentage of CB and PP has been fixed which is 25 wt.% and 20 wt.% respectively and the weight percentage of G will various from 55 wt.% to 54.2 wt.% according to CNTs loading. The result shows that the G/CB/CNTs/PP composite with 0.2 wt% CNTs has the higher electrical conductivity 295.78 S/cm.

Simultaneous Optimization for Multiple Responses on the Compression Moulding Parameters of Composite Graphite – Polypropylene Using Taguchi Method

This research concerns the effect of compression molding parameters on conducting polymer composite (CPC) properties such as electrical conductivity and flexural strength. In the present work on CPC, focus is given to graphite (G) as filler and polypropylene (PP) was use as the binder. The Taguchi’s L9 orthogonal array has been used as design of experiment (DOE) while the electrical conductivity and flexural strength were assumed to be quality characteristic (responses). The electrical conductivity was measured using four point probes and flexural strength was measured using three point tests according to ASTM D638. Classical analysis of variance (ANOVA) was used to investigate the significant of each compression molding parameters and finally propose the optimum compression molding parameters. But for several responses, the optimum condition for one response is not very likely to the optimum condition for other response.

Investigation on the fatigue life characteristic of kenaf/glass woven-ply reinforced metal sandwich materials

Fatigue life characteristic of hybrid composite reinforced metal laminate is a notable investigation since this kind of material offers several superior characteristics over conventional metallic alloy. A majority of the researches have focused on the mechanical properties of hybrid composite and conventional fibre metal laminate such as glass reinforced aluminium epoxy and aramid fibre reinforced aluminium laminate. However, investigation on the fatigue life behaviour of hybrid composite reinforced metal laminate still remains unexplored. In this study, the fatigue life characteristic of hybrid kenaf/glass reinforced metal laminate with different fibre configurations, orientation and stress ratio was presented. Fibre metal laminate was manufactured through hot press moulding compression method using annealed aluminium 5052 as the skin layers and the composite laminate as the core constituent. Tensile test was conducted at a quasi-static rate in accordance with ASTM E8 while tension–tension fatigue test was conducted at force controlled constant amplitude according to ASTM E466. Experimental results revealed that fibre metal laminate with 0°/90° fibre orientation exhibited better tensile and fatigue properties compared to fibre metal laminate with ±45° fibre orientation regardless of the woven-ply fibre configurations. Besides that, it was identified that higher stress ratio improves the fatigue life cycle of the fibre metal laminate structures.

Effect of Stannum on Properties of Graphite/Stannum Composite for Bipolar Plate

Over the past decade, rapid progress has been made in the understanding and development of Hybrid Conductive Composite (HCC) to be used as bipolar plate, one of the most important components in Polymer Exchange Membrane Fuel Cell (PEMFC). The formation processes of HCC and loading ratios of composite have significant effects on their properties especially electrical and mechanical properties. Thus, the research focuses on Graphite (Gr) as a filler and Stannum (Sn) as a binder in fabrication of HCC as a bipolar plate. The fabrication process began with Gr and Sn needed to dry mixed used ball mill with several ratios of loading, which are 60/40, 70/30 and 80/20 respectively. The shape of this composite was molded with a diameter of 25 mm through hot compression machine to form discs. The effect of different loadings on the properties such as electrical conductivity, bulk density and microstructure were observed and confirmed to be able to meet the DOE target properties as PEMFC bipolar plates. The result showed that Gr/Sn composite with 20 wt% Sn had the highest electrical conductivity which was 720 S/cm. In the other side, the bulk density showed decrement as Sn contents increased from 1.71 to 1.48 g/cm3. The findings promise an enhanced performance of HCC as a bipolar plate to be used in PEMFC which is beneficial for mobile and portable application industry. A further study on agglomeration and the mechanical properties such as the flexure strength and hardness should be pursued.

Effect of Different Filler Materials in the Development of Bipolar Plate Composite for Polymer Electrolyte Membrane Fuel Cell (PEMFC)

In Polymer Electrolyte Membrane Fuel Cell (PEMFC), bipolar plate is considered one of the most important components. Bipolar plate has a multi-functional in the fuel cell stack. The materials used in producing bipolar plate are greatly affecting its final properties. Through this study, the properties of bipolar plate composite will be observed. The based composition of this composite is 80% for multi-filler material and 20% binder material. Polypropylene (PP) will be used as binder material and for filler materials, Graphite (Gr) is the main filler and for the second filler materials its will vary with the usage of Carbon Black (CB), Iron (Fe), and Aluminum (Al) powder. The formation of this composite is produced through compression molding. The effect of different filler material loading on the properties such as electrical conductivity, bulk density and shore hardness are observed. The result showed the increasing of electrical conductivity as the increased the CB and Fe loading. But for Al, the result showed the decreasing of electrical conductivity as the loading of Al has been increased. Meanwhile the usage of CB clearly shown an improvement in electrical conductivity and able to meet the DOE target properties for development of PEMFC bipolar plate.

Preliminary Investigation to Determine the Suitable Mixture Composition for Corn Starch Matrix

The use of natural fiber as reinforcement in polymeric composites has been seen a dramatically increase over the last decades. The surge in the interest of natural fiber composite or biodegradable composite is mainly due to the attractive cost of production, improved of hardness, better fatigue endurance and good thermal and mechanical resistivity. In this work, corn starch in the form of powder is utilized as the matrix of the composite. However, starch is brittle and has low strength make it inappropriate candidate for matrix binder. The main objective of this study is to modify the mechanical properties of pure corn starch by mixing it with water, glycerol and vinegar. The composition ratio of water is 60~80%, corn starch 10~35%, glycerol is 5~15% and vinegar is 0~5%, ten samples (A-J) have been manufactured and the best mixture composition is selected based on few selection criteria. The selection criteria are visual impaction, hardness and density. From the results, the samples without vinegar are not suitable to be used because of the fungus availability on the surface. Meanwhile the results from the samples with 5 ml vinegar have no fungus on their surface even has been exposed to the ambient air. While the sample C has shown the best sample based on the visual, hardness and density test.

Effect of formation temperature on properties of graphite/stannum composite for bipolar plate

Bipolar plates are key components in Proton Exchange Membrane (PEM) fuel cells. They carry current away from the cell and withstand the clamping force of the stack assembly. Therefore, PEM fuel cell bipolar plates must have high electrical conductivity and adequate mechanical strength, in addition to being light weight and low cost in terms of both applicable materials and production methods. In this research, the raw materials used to fabricate the high performance bipolar plate are Graphite (Gr), Stannum (Sn) and Polypropylene (PP). All materials used was in powder form and Gr and Sn act as fillers and the PP acts as binder. The ratio of fillers (Gr/Sn) and binder (PP) was fixed at 80:20. For the multi-conductive filler, small amount of Sn, which is 10 up to 20wt% (from the total weight of fillers 80%) have been added into Gr/Sn/PP composite. The fillers were mixed by using the ball mill machine. The second stage of mixing process between the mixer of fillers and binder is also carried out by using ball mill machine before the compaction process by the hot press machine. The effect of formation temperatures (160°C-170°C) on the properties of Gr/Sn/PP composite had been studied in detail, especially the electrical conductivity, bulk density, hardness and microstructure analysis of Gr/Sn/PP composite. The result shows that there are significant improvement in the electrical conductivity and bulk density, which are exceeding the US-DoE target with the maximum value of 265.35 S/cm and 1.682g/cm3 respectively.

Influence of Heat Treatment on Impact, Hardness and Fatigue Strength of 6061 Aluminium Alloy

This paper presents effects of heat treatment on toughness, hardness and fatigue strength of aluminum alloy 6061. The alloy specimens were heat treated in the furnace at different temperature levels and holding times; and then cooled in different media (water and oil). The mechanical properties such as hardness, impact and fatigue were examined using standard method. Result shows that mechanical properties of aluminum alloy can be improved by the heat treatment. It was found that through ageing processes at temperature 160 °C for one, three and five hours, decreased the hardness, while increased the toughness. The fatigue strength was decreased when the number of cycles increased. The fracture surfaces between specimens have a different appearance before and after heat treatment.

Study of Interfacial Shear of Aluminium/Oil Palm Empty Fruit Bunch Fiber Reinforced Polypropylene Fiber Metal Laminates

This paper examines the interfacial shear properties of a new fiber metal laminates based on oil palm fiber reinforced polypropylene. The adhesive shear strength based on two type of surface treatment technique had been studied to determine the best technique to ensure a good bonding for fiber metal laminates based on oil palm empty fruit bunch fiber reinforced polypropylene (EFB pp) composite and aluminium 6061. Adhesion between aluminum and EFB pp composite was achieved by incorporating modified polypropylene adhesive film and surface treatment of Al sheets. Differential Scanning Calorimetry test showed the suitable bonding temperature between the composite and glue to be between 140°C to 155°C which is lower than the melting temperature of polypropylene. The applied surface treatment of ethanol solvent wipe and NaOH chemical etch though have effect on the surface roughness but have no significant effect on the maximum adhesion shear stress. The modified polypropylene adhesive film selected for this work is suitable to bond EFB pp composite with aluminium 6061 and both surface treatment is equally suitable.

Fracture Toughness of AZ61 Magnesium Alloy with Various Thickness

The critical fracture toughness parameter KΙC of AZ61 magnesium alloy was determined on the three point bent specimens with notch designed according to ASTM E399 standard. Five specimens having different thickness, i.e., 2, 4, 6, 8 and 10 mm were considered in order to evaluate the effect on fracture toughness. The stress intensity factor range ΔK was constant ~1x 10-8 for every specimen until the critical crack length reached half of the width of the specimens. The fracture test was done with the speed rate 0.12-0.15 MPa√m/sec until the specimens broke. The experimental results showed that the critical plain strain fracture toughness KΙC is 12.6 MPa√m and the highest plain stress fracture toughness KC is 16.5 MPa√m.