Key Engineering Materials Vols. 594-595

Abstract: This paper is focused to investigate the effect of treated natural fiber (typha latifolia) content on tensile and morphology properties of polylactic acid (PLA)/treated typha latifolia (T-TyLa) composites. The composite was compounded using heated two roll mill and the composite samples were prepared through compression molding. Tensile test and scanning electron microscopy (SEM) analysis were carried out to study the properties of PLA/T-TyLa composites. The results showed that the tensile strength of PLA/T-TyLa composites was decreased for about 43% with initial addition of T-TyLa content. The tensile modulus of the composites was increased (23%-91%) with increasing of fiber content. However, increased in fiber content reduced the elongation at break for about 53%-67% of PLA/T-TyLa composites. The optimum increment was obtained at 30 wt% of fiber content. SEM results showed that fiber dispersion was better for PLA/T-TyLa composites at lower fiber content.

Abstract: In this work, the closed-cell aluminium foams were fabricated via powder metallurgy route with organic space holder which also known as carbamide (urea). Carbamide was added with aluminium powder at different compositions from 50wt% to 70wt%. Then the influences of sintering temperatures were also investigated at 500°C, 550°C and 600°C. Physical and mechanical tests were conducted on the fabricated closed cell aluminium foam samples. The result showed that the porosity inversely proportional with density, that means the porosity decreases as the density of the foam increased. Also, it was revealed that the highest compressive strength was obtained at sintering temperature of 550°C. However, the compressive strength of the closed-cell aluminium foam decreased at the sintering temperature of 600°C. This is due to the occurrence of oxidation problem. It can be concluded that carbamide can be proposed as one of the organic space holder material in the fabrication of closedcell aluminium foam. Then, the experimental parameters such as sintering temperature, type of space holder and composition gave great influence to the mechanical and physical properties of the fabricated closed-cell aluminium foam.

Abstract: Sodium ion conducting gel polymer electrolyte (GPE) films consisting of polyvinylidenefluoride-co-hexafluoropropylene (PVdF-HFP) as a polymer host were prepared using the solution casting technique. Sodium trifluoromethane-sulfonate (NaCF₃SO₃) was used as an ionic salt and the mixture of ethylene carbonate (EC) and propylene carbonate (PC) as the solvent plasticizer. The GPE films were found to be stable up to temperature of 145 °C as shown by TGA analysis. The AC impedance study show that the optimum conductivity of 2.50 x 10^-3 S cm^-1 at room temperature is achieved for the film containing 20 wt.% of NaCF₃SO₃ salt. The temperature dependence of conductivity obeys VTF relation in the temperature range of 303 K to 373 K.

Abstract: Polypyrrole (PPy) conducting polymer prepared by chemical oxidation method using FeCl₃.6H₂O as an oxidant has exhibited 100% adsorption efficiency for the removal of nickel ions from aqueous solution. At pH 7, 100% nickel absorption was found by the prepared polypyrrole as measured by atomic absorption spectrophotometry. At both acidic and alkaline solutions, the adsorption efficiency of PPy was substantially lowered. The effects of pH, the initial concentration of nickel stock solution and the contact time on the uptake of nickel ions were also investigated. With the variation of initial concentration from 1-5 ppm, the initial concentration of 1 ppm nickel has been found to be adsorbed fully (100%) by the prepared polypyrrole. The contact time of 8 hours has been found to be the highest effective contact hours as beyond this there was no adsorption effect. The FTIR results confirmed the presence of nickel ions in the polymer matrix after adsorption.

Abstract: Plant based biopolymers are abundantly and easily available naturally biodegradable raw materials to prepare slow release nitrogen technologies. To test the lignin loading effect on biodegradability of the slow release fertilizer (SRF) and nitrogen release applications, a pot experiment under real soil conditions was conducted. Lignin at different loading percentages 5%, 10%, 15% and 20% were mixed with urea-modified tapioca starch acting as slow release fertilizer (SRF). Increasing the percentage of lignin to starch reduced the weight loss with improved nitrogen slow release properties in wet soil. Soil microbial biomass was negatively correlated with increase of lignin percentages. Lignin is a low cost biopolymer and can be used to improve starch biodegradation and its slow release nitrogen properties.

Abstract: The effects of dynamic vulcanisation in vPE/rPE/EPDM blends were studied. The discarded polyethylene used in the study was obtained from local cable manufacturers. The effects of different sulfur loading on the tensile properties and morphology of the thermoplastics elastomer blends were examined. Results show that the tensile properties (except E_B) increased as increasing in sulfur loading. Scanning electron microscopy indicates that a uniform distribution of vulcanised EPDM in vPE/rPE/EPDM blends.

Abstract: The virgin polyethylene (vPE) and recycled polyethylene (rPE) was melt blended with ethylene propylene diene terpolymer (EPDM) in different ratio by using a Haake Rheomix at 180°C and 50 rpm were prepared. The characterization such as tensile properties and morphology were examined. Results indicated that, the tensile strength and youngs modulus of vPE/rPE/EPDM with CB show the highest value compared to silica and CaCO₃ except for elongation at break. The scanning electron microscopy (SEM) studies proved that, better dispersion and less agglomeration of CB and silica filled particles as compared to the CaCO₃.

Abstract: This paper presents a part of the results from an experimental study of strain distribution on reinforcement of concrete beams reinforced with glass fiber-reinforced polymer (GFRP) bars. Under static loading conditions, eight concrete beams reinforced with GFRP bars were tested and as comparison eight beams with steel reinforcement were also tested. All of the beams were prepared with varying ratios of longitudinal reinforcement bars and stirrups. The effect of shear span-effective depth ratio on strain distribution of longitudinal reinforcement was also observed. Furthermore, the behavior of strain on stirrups due to different materials of longitudinal reinforcement was also discussed in this report. The test results show that the ratio of longitudinal reinforcement significantly influence the strain distributions on reinforcement where the beams with higher ratio exhibit higher strain. Moreover, it was also obtained that the different types of longitudinal reinforcement considerably influences the strain behavior on stirrups as higher strain was observed in beams reinforced with GFRP bars.

Abstract: Films of methyl cellulose (MC) /chitosan blends were prepared via solution casting technique and their properties with different amount of ammonium trilate, NH₄CF₃SO₃ were compared. Measurements of conductivity as a function of frequency at room temperature on these films were carried out using HIOKI 3532-50 LCR Hi-Tester where the frequency was set between 50 Hz to 1 MHz. Samples having 40 wt% of NH₄CF₃SO₃ exhibit the highest room temperature conductivity of (4.99±4.18) x 10^-6 Scm^-1. Dielectric data were analyzed using complex permittivity and complex electrical modulus for the sample with the highest ionic conductivity.

Abstract: Biocomposites demands are significantly rising due to environmental regulations and concerns. However, incompatibility between the fibre and matrix is a major setback that diminishes the biocompostie properties. Therefore in this work, methylene diphenyl diisocynate (MDI) compatibilizers were used together with fibre surface treatment in order to increase compatibility between polylactic acid (PLA) and Elaeis Guineensis Fibres (EGF) biocomposite. Nonisothermal properties were investigated and it was found that, MDI increased compatibility of the PLA and EGF which led to the restriction of chain movements in the biocomposite. This restriction in chain mobility caused an increase the glass transition temperature and crystallization temperature and also reduced the degree of crystallinity.