Advanced Materials Research Vol. 686

Abstract: Nanocomposite fibers produced via electrospinning have very large surface area by virtue of their nanometer diameter sizes thereby making them very attractive for various applications such as for adsorption of contaminants from wastewater. In this study, a highly adsorbing nanoparticle, iron-modified montmorillonite was used as filler in the nanocomposite. The effects of polymer solution and suspension properties such as polymer concentration, clay loading, and filler type on the electrospinning of the nanocomposite were investigated using a 2k factorial design of experiment. The types of montmorillonite used were zero valent iron-MMT (ZVIMMT) and iron (III)-MMT (FeMMT). It was found from the SEM images that finer fibers were generated from suspensions with lower polymer concentration in the solution specifically at 5 wt% and from suspensions with ZVIMMT particles as filler. However, a common defect in nanofibers called beads was also observed in the fibers produced from 5 wt% polymer concentration. TEM micrographs confirmed that the ZVIMMT fibers have smaller diameter than the FeMMT fibers. In addition, it was recognized that the layered structure of the clay is still intact after the electrospinning process. The XRD pattern of the fibers revealed that the clay particles were intercalated with the polymer molecules based on the calculated d-spacing. Furthermore, elemental analysis on the bead and string regions of the electrospun fibers confirmed the presence of polymer and montmorillonite particles in both regions.

Abstract: An electrochemical anodization is a simple and low cost technique, to electrochemically synthesize self-organized titanium dioxide (TiO2) nanotubes (NTs) from 1M Na2SO4 electrolyte with anodization of Ti foil. The FESEM results showed that the average diameter size and length of TiO2 NTs was found between 50 to 60 nm and 2.5 μm, respectively. The surface morphology of arrays TiO2 NTs is uniformly deposited on Ti substrate. While, the cross-sectional of TiO2 NTs revealed that, the TiO2 NTs is arrays alignment and close each other deposited. From current-anodisation time analysis (I-t) indicates that TiO2 nanotubes were start formed at anodisation time 429.03 sec with current flows is 51.69 mA in electrochemical system.

Abstract: Ultraviolet (UV) sensors have variety of applications. In this work, a new transparent UV sensor is developed based on zinc oxide (ZnO) films. The ZnO films with 350 nm thicknesses were fabricated on glass substrates by using direct current (DC) plasma magnetron sputtering technique. The ZnO UV sensors are characterised by using current-voltage (I-V) measurements at room temperature. The current is measured by applying small bias voltage under the white light, UV light (325 nm), and dark condition and the photocurrent responses extracted from the I-V measurements are compared. The transparent UV sensors based on ZnO films deposited at high substrate temperature of 450 °C exhibit most significant photocurrent response under UV irradiation.

Abstract: In this paper, the simple synthesis of polyaniline/silver composites through interfacial polymer method was studied. Polyaniline-silver composites were produced at room temperature by using ammonium persulphate as an oxidant agent in presence of silver nitrate (AgNO3). Field Emission Scanning Electron Microscopy (FESEM), X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) techniques were used to characterize the synthesized product. FESEM results showed the core shell shape of composites that the layer of polyaniline covered the silver particles. XRD results showed the high crystalline behaviour of the polyaniline/silver composites due to presence of silver. FTIR results also showed the successfully synthesis of the composite. This paper aims to study on synthesis and characterization of polyaniline-silver composites.

Abstract: Palm empty fruit bunch (EFB) is an abundant by-product resulted from massive palm oil production in Malaysia as one of the world's largest exporter and second largest producer of palm oil. This agricultural waste is usually disposed in nature, burnt in opened atmospheres, or used as a fuel for boilers. Such conventional handlings of EFB have created environmental concerns to Malaysia such as air pollution and release of green house gases (CH4 and CO2). This study made use of such biomass in the production of cost effective nanoporous material, namely activated carbon fiber (ACF) which able to diminish the problem of waste disposal, and at the same time to turn waste into wealth. This is especially beneficial when the ACF is used for environmental friendly application such as adsorbed natural gas (ANG) technology. ACF was formed from carbonaceous materials via process of carbonisation and activation. Both chemical and physical activations were carried out by using H2SO4 and CO2, respectively. In pyrolysis, carbonisation was conducted at temperatures i.e. 400, 600, 800 and 1000 °C in nitrogen (N2) atmosphere. Surface morphologies, microstructures, pore structures and surface chemistry of these samples were investigated for the characterisation of EFB fiber-derived ACF. Above 80% of the total pore volumes for the samples were contributed by the micropore as the major pore components in the ACF produced. The samples exhibited an high BET surface area , dominant micropore volume up and narrow pore size distribution in micro range (< 1.5 nm).

Abstract: A mathematical model for plates with partially delaminated layers is presented to investigate their behavior. In this formulation account is taken of lateral strains. The principal advantage of the element is that it allows the modeling of delamination anywhere in the structure. The region without delamination is modeled to carry constant peel and shear stresses; while the region with delamination is modeled by assuming that there is no peel and shear stress transfer between the top and bottom layers. Numerical results of the present model are presented and its performance is evaluated for static problems. Laminated beams and plates are often used as primary load-carrying structures. However, the mechanical properties of composite materials may degrade severely in the presence of damage. One of the common types of damage modes in laminated composites is delamination. The presence of delamination is one of the most prevalent life-limiting failure modes in laminated composite structures. Many researchers had been studying the effect of delamination. Wee and Boay [1] developed an analytical model to predict the critical load of a delaminated composite laminated beam. Lee et al. [2] investigated the buckling behavior of the beam plate with multiple delaminations under compression. Kapania and Wolfe [3] examined the buckling behavior of a beam plate with two delaminations of equal length. Wang et al. [4] improved the analytical solution by including the coupling between the flexural and axial vibrations of the delaminated sub-laminates. Lee et al. [5] studied a composite beam with arbitrary lateral and longitudinal multiple delamination. Finite-element methods have been developed using the layerwise theory by Kim et al. [6]. Tan and Tong [7] developed a dynamic analytical model for the identification of delamination embedded in a laminated composite beam. To investigate the effects of delamination of a plate layers, a finite-element model is developed. Both displacement continuity and force equilibrium conditions are imposed between the regions with and without delamination. The accuracy of the approach is verified by comparing results with previously published data.

Abstract: Oil palm empty fruit bunch (EFB) is an abundant agricultural waste available in Malaysia. More than two million tonnes (dry weight) of extracted oil palm fiber are estimated to be generated annually. Usually the EFB is used as boiler fuel to produce steam in the palm oil mills. EFB fiber can be used to prepare activated carbon fiber (ACF) by carbonization and activation. Conversion of EFB fiber to ACF will reduce the amount of agricultural waste produced annually and it represents a potential source of adsorbents used for adsorption. The ACF has many advantages as compared to the conventional activated carbon found in powder or granular form. These advantages include large surface area, high adsorption capacity and high rates of adsorption from the gas or liquid phase. In this study, ACF produced from EFB fiber by single step direct activation process (ACF-D) was compared against ACF produced by conventional 2-step carbonization and activation (ACF-ND). The different properties between ACFs produced were investigated. The raw EFB and ACFs were characterized by a SEM and EDS, FTIR and XRD. The results show that EFB has carbon content of 63.33 weight percentage (wt %) with oxygen content of 36.67 wt %. ACF-D was found to have a high carbon content of 93.63 wt%, with low oxygen content (5.19 wt %). ACF-ND gave a higher carbon content up to 95.68 wt% and accompanied by a lower oxygen content (3.85 wt %).

Abstract: This paper presents the monitoring of resin flow during resin infusion process in the fabrication of glass fiber reinforced polymer GRP wind turbine blade (WTB). Epoxy type of resin was used as the matrix and its viscosity and gel time were determined in-house. Next, resin infusions were done to obtain the permeability of the glass fiber in different directions (longitudinal and transverse), given the specific number of layers. The fabrication of composite WTB by resin infusion was conducted with the introduction of 'moldless' setup, where both upper and lower skins are covered by flexible mould/vacuum bag without any rigid female mould. However, a wooden core is used and acts as an “inner” mould to obtain the wind turbine shape. The whole infusion process was video recorded and the flow front pattern was traced at certain time intervals to investigate the infused percentage area over time. Afterward, guided by the traces of flow patterns on grid and video observation, 3D models of resin infused at interval times are generated in a CAD software. From the models, the area infused was determined. Percentage of area infused over time was compared with the analytical plot based on Darcy's law. A good agreement was found between the experimental observation and the theoretical plot.

Abstract: Hybrid composites prepared by using oil palm empty fruit bunch (EFB) and jute fibres as reinforcement in epoxy matrix by keeping the EFB/jute fibre weight ratio constant at 1:1. In this study, effect of coupling agent on tensile and flexural properties of oil palm empty EFB/jute fibres reinforced epoxy hybrid composites evaluated. Hybrid composites are prepared by using hand lay-up technique. Particular interest is the effect of coupling agent (CA), 2-Hyroxy ethyl acrylate (HEA) on the tensile and flexural properties of hybrid composites. The laminates coupled with HEA showed better tensile and flexural properties than the one without coupling agent. The highest tensile and flexural strength value has been obtained for hybrid composite of jute/EFB/jute (CA). Tensile fracture composite specimens were analyzed by using scanning electron microscopy (SEM) to know the morphological behaviour of composites. Thermal properties of the hybrid composites were investigate to observe the effect of 2-Hyroxy ethyl acrylate (HEA) on thermal stability of hybrid composites.

Abstract: Semi-metallic friction composites (SMFC) consist of epoxidised natural rubber with 50 mol % epoxidation (ENR50), alumina nanoparticle, steel wool, graphite and benzoxazine were prepared by melt mixing using Haake internal mixer at 90°C and 60 rpm rotor speed. The composites were vulcanized using different crosslinking systems, namely, sulfur and electron beam (EB) crosslinking. The samples were subjected for friction test in order to determine friction and wear properties of SMFC. The friction–wear properties of the SMFC crosslinked by electron beam irradiation and sulfur vulcanization system were compared. The friction coefficient in normal and hot condition of irradiated SMFC were higher than those of sulphur vulcanized samples at all applied doses. On the other hand the specific wear rates of irradiated samples were lower than the sulfur vulcanized samples at all applied doses. The sample crosslinked by EB irradiation at 150 kGy dose found to exhibit the best tribological property, as evident from the higher friction coefficient (about 0.461) and lower wear achieved at 150 kGy irradiation as compared to sulphur vulcanization of the SMFC.