Rose Farahiyan Munawar

Design synthesis of 5.8 GHz octagonal AMC on a very thin substrate

This paper proposed a development of 5.8 GHz Artificial Magnetic Conductor, AMC using very thin substrate with thickness of 0.13 mm. Different shapes of PEC metallization are discussed in order to achieve the highest bandwidth of unit cell AMC. Another approaches for increasing the bandwidth is by applying the ring patch around the substrate as well as implementing the DGS ground plane. The proposed design produces 1.96 % bandwdith of unit cell. Applying the 2 x 4 unit cell arrangement gives the best result for directivity equal to 6.75 dBi, gain of 6.83 dB, efficiency = 98.41 % and return loss = -45.63 dB.

Non-Covalent Polymeric Wrapping of IGEPAL C0890 for Graphene Nanoplatelets (GNPs-C0890) Filled NR/EPDM Rubber Blend Nanocomposites

Graphene nanoplatelets (GNPs) surface modification was performed by using a simplified dual-action of ultrasonication and high speed mechanical shearing. This approach induced a non-covalent polymeric wrapping interaction between GNPs surfaces with IGEPAL-C0890 (ethoxylated nonyl phenol with 40 moles ethylene oxide). Various characterization tools like FTIR, Raman spectroscopy, FESEM and TEM were utilized to confirm the success of the surface treatment. The efficacy and suitability of non-covalent treated GNPs-C0890 as nanofiller reinforcement and inorganic compatibilizer in NR/EPDM rubber blends were evaluated. Effects of GNPs-C0890 loading variation to the mechanical tensile properties and fracture morphologies of NR/EPDM nanocomposites rubber blend were studied. It is interesting to note that the GNPs-C0890 was not able to reinforce NR/EPDM blend at a higher loading addition (≥ 3.00 wt.%) due to the agglomeration and crosslinking retardation phenomena by phase separation. However, at a lower loading (≤ 1.00 wt.%), the blend strengthening effects promise the improvement at about 64.55% of tensile strength and 14.20% of elongation percentage as compared than unfilled NR/EPDM blend. Obvious fractured morphological changes due to the absence and presence of GNPs provide hints on the role of GNPs treatment in effecting the NR/EPDM rubber blend mechanical properties.

Effects of Particulate Types on Biomass Particulate Filled Kenaf/Polypropylene Composite

The application of natural fibers in composite is very encouraging because of its many benefits such as more environmental friendly and cost reduction. Recently, there is an interest on the application of kenaf-based material for high-end uses such as in automotive industry. In this research, mechanical properties of kenaf fiber reinforced polypropylene (KFRP) composite added with two different types of bio-based fillers, i.e., oil palm shell particle (OPSP) and rubber seed shell particle (RSSP) are studied. The composites were prepared by melt mixing of the materials using internal mixer, followed by compression molding process using hot press machine. The tensile and flexural strength were found to increase with the addition of OPSP as well as RSSP. However, KFRP composite added with RSSP showed better tensile, flexural and impact properties as compared to the composite added with OPSP. From microscopic observation of the raw OPSP and RSSP particles, it was observed that OPSP showed a more granular shape, while RSSP particles were flakier in shape. This difference in particle shape is believed to affect the mechanical properties of the composites as demonstrated in this study.

Magnetic and Microwave Absorption Properties of Magnetite-Durian Shell Nanocomposite Sheet in Gigahertz Range

In this paper, a novel microwave absorber of thin, light weight, flexible, green and low cost magnetic nanocomposite sheet that can work in high frequency range is fabricated. The vast and increasing numbers in electronic and telecommunication devices has create electromagnetic interference (EMI) in which may lead to application disturbance. Therefore, electromagnetic (EM) wave absorber with the ability of high absorption rate is strongly demanded. Here, durian shell (Durio zibethinus Murray) embedded magnetite (Fe3O4) nanocomposite sheets were prepared via pulping and lumen loading technique. The nanocomposite sheets were fabricated by varying the weight percentage of the filler content (2-10 wt% of Fe3O4) at constant thickness and varying the thickness of the sheets (0.1-1.0 mm) at constant filler content. FESEM micrograph shows that the Fe3O4 nanoparticles are in cubical and spherical shape with the 20–50 nm of size range. The microwave absorption properties of the sheets were tested by a vector network analyze (VNA) in the frequency range of 4-18 GHz. The samples were also tested using vibrating sample magnetometer (VSM) in order to study the magnetic properties. The absorption or maximum reflection loss (RL) of the samples increases continually and the increase of both filler content and sample thickness has led to the shift of dip to lower frequency region.

Electroless Ni-Co-Cu-P Alloy Deposition in Alkaline Hypophosphite Based Bath

The use of electroless deposition method to deposit nickel alloy attracts attention due to its uniformity, corrosion resistance in neutral media and low friction. Quaternary nickel alloy deposit can be achieved by adding metal ion additive into the plating bath. Furthermore, the use of alkaline bath can accelerate the deposition rate, and provide sufficient thickness for corrosion protection. In this study, an electroless quaternary nickel alloy is deposited on iron coupons by adding cobalt and copper ions in hypophosphite based Ni-P alkaline bath. The nickel alloy deposit surface morphology is studied using scanning electron microscope (SEM) and x-ray fluorescence (XRF). Corrosion behavior of the nickel alloy is investigated using polarization curve measurement in 3.5wt% NaCl aqueous solution. From the results, the elecroless Ni-Co-Cu-P alloy coating produced at higher plating bah pH is harder than the lower bath pH. Higher Co, Cu and P content in the Ni alloy exhibit broader passive area in the polarization curve measurement results.

A Facile Coating Method for Superhydrophobic Magnetic Composite Sheet from Biodegradable Durian Peel for Electromagnetic Wave Absorbance Application

Most of the electromagnetic (EM) wave absorbers are commonly made from polymer-based materials. A large number of polymers are resistant to the environmental degradation and are thus responsible for the buildup of polymeric solid waste materials. These solid wastes cause acute environmental problems and remain undegraded for quite a long time. In a view of the awareness and concern for the problems created by the polymeric solid wastes, new biodegradable cellulosic composite with low cost and nontoxic materials, have been designed and developed. However, the properties of natural fibers that tends to absorb water, thus limiting their application. In this study, precipitated calcium carbonate (PCC) was added with stearic acid (SA) in order to generate a hydrophobic coating formulation. PCC works as filler and SA acts as surface hydrophobic modification agent. Polymer latex was then added to the coating compound as the binder. The composite surface morphology was inspected using scanning electron microscope (SEM). Results show that durian peel composite sheet had successfully achieved a superhydrophobic surface with a water contact angle of 154.85° which exceed 150°.

Cure Characteristics of Natural Rubber/EPDM Blends for the Effect of MAH Grafted EPM and Compounding Parameters via Response Surface Methodology

Natural Rubber/EPDM blends were successfully prepared by direct melt compounding method using an internal mixer. The significance of MAH grafted EPM (MAH-g-EPM) and compounding parameters were studied via the response surface methodology (RSM) using the two-level full factorial design. The MAH-g-EPM loading, mixing temperature, rotor speed and mixing time were selected as four independent variables. Cure characteristics of scorch time, cure time and maximum torque were selected as the responses. The statistical significance of all variables and their interactions during compounding were analysed using ANOVA. The degree of agreement between experimental results with those predicted by the statistical model was confirmed using constant of determination, R2 with values approaching ~0.99. It was observed in the results, that the incorporation of high loading (10 phr) of MAH-g-EPM has predominantly enhanced the scorch safety time of NR/EPDM blends, as well as increased the modulus of NR/EPDM blends to some extent compared to low loading (5 phr and 7.5 phr). These finding were further supported by the Differential Scanning Calorimetry (DSC) analysis.

Cyclic Voltammetry Analysis of Carbon Based Electrochemical Capacitor in Aqueous Electrolytes

In this study, a mixture of activated carbon (AC) and graphene (G) was coated onto the stainless steel (SS) mesh to produce an electrode for the electrochemical capacitor (EC). Different materials, such as carbon nanotube (CNT) mixed with G, were also used in this experiment to compare the electrochemical properties of both electrodes. The electrochemical properties of the electrode were determined by using cyclic voltammetry (CV). The CV curves of the AC/G electrodes showed good capacitive behaviour, and the highest capacitance values obtained for AC/G and CNT/G electrodes in 1M H2SO4 at 1 mVs-1 were 13 Fg-1 and 4.34 Fg-1, respectively. Meanwhile, the highest capacitance values obtained in 6M KOH at 1 mVs-1 were 14 Fg-1 and 12.07 Fg-1 for AC/G and CNT/G electrodes, respectively.

Development of Green Composite: Pineapple Leaf Fibers (PALF) Reinforced Polylactide (PLA)

Green composite material has become the most desired material to replace polymer composites made from fossil oil. Besides having advantages over its biodegradability and quality performances, the material sources are abundant and renewable. Therefore, this research focused on developing green composite which is derived from a combination of pineapple leaf fibers (PALF) and Polylactide (PLA). PALF is extracted from pineapple leaves which are easily found during harvesting pineapple plantation. In order to study the influences of different fibres characterization, the fibres were extracted from different types of pineapple available in Malaysia, namely Moris Gajah, Jasopine, Maspine, and N36. The main objective of this study was to investigate the physical and mechanical properties of this green composite. The physical testing was carried out to determine water absorption while the tensile and bending tests were conducted for mechanical testing. For the purpose of comparing the material properties, PALF reinforced polypropelene (PP) was developed too. Based on the result, Jasopine fibre shows the highest tensile and flexural strength for the combination of both polymers in comparison to the other types of PALF.

Green magnetic composite sheet from durian shell and nano magnetite particles

Biomass-derived materials such as kenaf pulp and wood chips are a perfect candidate to produce magnetic paper. Furthermore, by using biomass waste, such as paddy straw, sugarcane, bagasse and durian shell, the cost of producing magnetic paper can be further reduced while giving added value to the waste. This paper investigates the potential of producing magnetic sheet from durian shell. Initially, durian shells were dried before undergoing the pulping process. The resulted sheet was then combined with magnetic particles, the nanomagnetite using either lumen loading or in-situ co-precipitation to produce a magnetic composite sheet. After being loaded with magnetic particles, the composite sheets were tested in terms of the homogeneity of the magnetic particles in the samples, degree of loading of the magnetic particles and the magnetic properties of the samples. Results obtained show a great success in producing the magnetic sheet from durian shell waste and nanomagnetite particles. It was also found that the lumen loading method gives better magnetic properties compared to the in-situ co-precipitation method.