Key Engineering Materials Vols. 594-595

Abstract: This work study the effect of empty fruit bunch (EFB) fiber on mechanical properties (tensile, flexural and impact) of different formulation of HDPE/EVA/MMT/EFB nanohybrid biocomposite with present of 1.5 phr compatibilizer. The ratio of HDPE and EVA are fixed at 80 wt% and 20 wt% respectively. However, the nanoclay montmorillonite (MMT) was varied from 0, 0.5, 1.0 and 1.5 phr. Meanwhile EFB fiber was varied from 0, 10, 20, 30, 40 and 50 wt%. The HDPE/EVA/MMT/EFB blends were prepared by melt extrusion blending technique using a single screw extruder. Generally, the result found that by increasing of EFB fiber content, the tensile strength of HDPE/EVA/MMT/EFB nanohybrid biocomposite was declined. The highest tensile strength was given by formulation of HDPE/EVA/1 phr MMT without EFB fiber loading which is 29.064 MPa. Meanwhile the lowest tensile strength is given by formulation of HDPE/EVA/0.5 phr MMT with 50 wt% of EFB fiber which is 9.673 MPa. Similar trend also showed by the result of flexural strength obtained. In contrast, the value of tensile modulus is progressively increased with further increasing of EFB fiber content. The highest tensile modulus given by formulation of HDPE/EVA/1 phr MMT with reinforced of 50 wt% EFB fiber loading (694.53 MPa) whereas the lowest is given by HDPE/EVA/0.5 phr MMT with 10 wt% EFB fiber loading (290.76 MPa). Similar trend for the flexural modulus where further increasing of EFB fiber content, the flexural modulus is directly increasing. Unfortunately, for impact properties, reinforced of EFB fiber give resulted on the reduction of impact strength.

Abstract: This paper presents the modelling of a general lifetime performance for glass fibre reinforced epoxy (GRE) composite pipes similar to the well-known Tsai-Hill interactive failure criterion. Tsai Hill criterion is based on the Von Misses distortional energy criterion which was modified to satisfy the orthotropic nature of GRE composite pipes. The effects of stress developed in each ply from ultimate elastic wall stress (UEWS) test were expressed in a single quadratic term of axial and hoop stress through laminate theory. The term then solved to produce limits with respect to axial and hoop stress, which represented in a graphical form of failure envelope. The modelled envelop shows a good agreement with experimental data from the multiaxial UEWS test of ±55° GRE composite pipes. This indicates that such model can be used to predict the long-term performance of GRE pipes under combine loadings.

Abstract: This paper evaluates the effects of glass fiber addition on the properties of fresh and hardened fly ash based geopolymer concrete (GPC) activated by 8 M NaOH solution (28.6%) + Na₂SiO₃ (71.4%) with a SiO₂/Na₂O ratio of 2.0. Glass fibers at the dosages of 0.50%, 0.75%, 1.00% and 1.25% by volume of concrete were added to the GPC mix. The properties of fresh and hardened glass fiber reinforced fly ash based GPC in terms of workability, density, compressive and flexural strengths were compared with those of the fly ash based GPC without using glass fiber. The experimental results indicated that inclusion of the glass fibers resulted in decrease of the workability but increase of the density, compressive and flexural strengths of the fly ash based GPC with increased fiber content.

Abstract: Curing characteristics and swelling behavior of natural rubber/styrene butadiene rubber/recycled nitrile glove (NR/SBR/rNBRg) blends were investigated. Eleven composition ratio; 50/50/0, 50/40/10, 50/30/20, 50/20/30, 50/10/40, 50/0/50, 40/50/10, 30/50/20, 20/50/30, 10/50/40, and 0/50/50 of SMRL/SBR/rNBRg with the size of rNBRg ; 2.5 3.0 cm² were prepared by using two roll mill at room temperature. Cure characteristics such as scorch time,t₂, cure time,t₉₀, minimum torque, M_L, maximum torque, M_H, and swelling behavior of SMRL/SBR/rNBRg ternary blends were examined. Results indicated that the scorch time and maximum torque of the NR/SBR/rNBRg blends decreased with increasing rNBRg content. The minimum torque of the blends increased as rNBRg content increased. The cure time of NR/SBR/rNBRg blends show a unique trend, which are depending on the domain rubber content. The increment in rNBRg content decreased the crosslink density of NR/SBR/rNBRg blends.

Abstract: One of the eligibility brakes requirements that used by railway is the fulfillment of the prescribed limit of friction coefficien. Test performed to determination railway brake block friction coefficient using pin on disc test. This test convert brake force into normal force on load cell that could be replace by balance. But due to the existing gap between arm force and brake force, error could be happened. To minimalized this error, that gap had to be reduced. In this research, the gap was reduced from 4.5 cm to 1 cm. Data recording was modified from manual recording into automatic recording using LabView program. This modified was very usefull because recording data could be done easily.

Abstract: The biocomposites were prepared by using kenaf bast fiber mat as reinforcing materials at different percentage. The kenaf bast fiber was treated with alkaline at different sodium hydroxide (NaOH) percentage. Composites which were made from treated alkaline kenaf treated bast fiber showed better mechanical properties (tensile) than those of the unmodified. Scanning electron microscope analysis showed the evidence of the enhancement of the compatibility between kenaf bast fiber and the matrix. The percentage of kenaf fiber in composites also plays a crucial role in determining the composite properties.

Abstract: This study is conducted to determine the effect of five variables on mechanical properties of geopolymer binders. These five variables are chloride environment, NaOH molarity, Na₂SiO₃/NaOH ratio, fly ash/alkaline activator (FA/AA) ratio and superplasticizer (SP) addition. The mechanical properties considered are compressive strength, porosity and density. Taguchi experimental design method is used to compile the binder composition of geopolymer to achieve the maximum compressive strength. Specimens binder used is a cylinder with 25 mm diameter and 50 mm height. Compressive strength test is performed at 28 days using SNI 03-6825-2002 (Indonesian National Standard) and porosity of the binder is determined using vacuum saturation apparatus similar to that developed by RILEM. The density of the binder is measured using Ultrasonic Pulse Velocity (UPV). This study concludes that the chloride environment has a beneficial effect on the compressive strength of the binder. In addition, the FA/AA ratio and NaOH molarity give a significant effect on the compressive strength of geopolymer binders.

Abstract: Composite polymer electrolytes (CPEs) comprised of hexanoyl chitosan-polystyrene-LiCF₃SO₃-TiO₂ were prepared by solution casting technique. The TiO₂ fillers were treated with 4% sulphuric acid (H₂SO₄) aqueous solution. The effect of treated TiO₂ on the structural and electrical behaviour of the prepared electrolyte systems was investigated by X-ray diffraction (XRD) and impedance spectroscopy, respectively. Addition of TiO₂ decreases the crystallinity of the electrolytes. Ac conductivity was calculated from σ(ω) = ε_oε_rωtanδ. It is found that at all frequencies, σ(ω) increases with increasing temperature. Dielectric constant decreases with increasing frequency and increases with increasing temperature.

Abstract: Drilling generated heat is considered to have significant effect on the product. In this study, woven glass fiber reinforced epoxy composites were fabricated using Vacuum Resin Infusion technique. The composites were drilled using HSS twist drill bit at various drilling parameters. The temperature during drill was measured using infra red thermometer. The damage factor of drilled holes was measured using 3D non-contact surface measurement and correlates it with temperature. Results showed that low feed rate recorded maximum temperature and high fede rate showed lower heat generated during drilling. Damage factor measured at lower feed rate was high and low at high feed rate. This was considered due to evaporation of resin matrix.

Abstract: The effect of excessive intermetallic growth to the reliability of solder joints become major problem in electronic devices industry. In this study, we used Sn-Cu-Si₃N₄ composite solder to observe the intermetallic compound (IMC) growth during low and high temperature aging. 50°C and 150°C represent low and high aging temperature respectively. Various isothermal of aging times were carried out by using 24hrs, 240hrs and 720hrs. The IMC thickness increases with increasing of aging temperature and time. Cu6Sn5 phase appear at low aging temperature whilst Cu₆Sn₅ together with Cu₃Sn phases has been observed at high aging temperature. The growth kinetics for low and high aging temperature is 1.63x10^-18μm2/s and 2.75 x10^-18μm2/s.