Advanced Materials Research Vols. 488-489

Abstract: The present article summarizes an experimental study on the mechanical and thermal behavior of recycled polypropylene composites reinforced with rubberwood flour. Different compositions were varied to investigate mechanical strengths, melting temperature, storage modulus, and loss modulus. It was observed that the tensile and flexural strengths decreased with the increase of wood flour content. Furthermore, the air cooled composites showed improved properties in comparison with the water cooled composites. The melting and crystallization temperature results presented a weak influence of increased wood flour content on composites. However, dynamic mechanical thermal analysis showed an increase in the storage and loss modulus.

Abstract: In recent years, for the purpose of achieving enhanced mechanical properties of fiber reinforced composites, hybridized composites containing a combination of two or more types of fiber reinforcements have been explored. Perhaps the main parameter which controls the mechanical properties of the hybrid composites is the flexibility to arrange the hybrid fiber reinforcement layers in a variety of ways within the hybrid laminate. In this study, low velocity drop weight impact resistance of plain weave woven glass and carbon hybrid composites has been investigated. The study explores the effects of intra-ply arrangement sequence on the impact resistance of 24 and 32 ply laminates in which glass and the carbon plies have been differently stacked. The results show that impact resistance of woven glass fiber composites can be enhanced by hybridizing woven glass fabrics with woven carbon fabrics. The results indicate that the impact resistance is a function of the positions of the glass and carbon layers in the hybridized inter ply laminates.

Abstract: Composite membranes were prepared by incorporating inorganic silica nanoparticles into blends of polysulfone/polyimide (PSF/PI) membranes via sol-gel route. Morphological structures of the developed membranes were carried out by scanning electron microscopy (SEM). Spectroscopic analysis of the hybrid membranes were done by fourier transform infrared spectroscopy (FTIR) analysis. Differential scanning calorimetry (DSC) analysis shows that the glass transition temperature (Tg) increased from 209oC to 238oC in the hybrid membranes followed by thermogravimetric analysis (TGA) that showed significant improvement in thermal stability of the developed membranes.

Abstract: In this study, the mechanical and thermal properties of green biocomposites adding natural dye were investigated by tensile test and Differential Scanning Calorimetry (DSC). Poly(lactic acid), one of biodegradable polymers recently been interested for replacing petroleum-based polymers, was compounded with wood fibers to produce biocomposite, and natural dyes were introduced to improve appearance of biocomposite. Pine wood fibers were dyed with three types of natural dyes; yellow color from heartwood of Jackfruit tree, red color from Sappan wood, and blue color from Indigo blue. Prior compounding, original and dyed wood fibers were treated with silane to improve compatibility between wood fiber and polymer matrix. It is found that %crystallinity of alkali-treated and natural dyed wood/PLA biocomposites were significantly higher than original wood/PLA biocomposites. The modulus and tensile strength of natural dyed wood poly (lactic acid) composites were in the same level of alkali-treated wood composites; however, elongation at break was improved by natural dye.

Abstract: Porous ZrO2-Al2O3 ceramic composites containing 0, 30 and 50 wt% Al2O3 were prepared by solid state sintering in the temperature range of 1375˚-1650°C and effect of temperature and alumina percentage on compressive strength and microstructure of monoclinic zirconia was investigated by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). XRD results on composite samples showed monoclinic ZrO2 and Al2O3 phases. SEM images showed uniform distribution of porosity in microstructure. Compressive strength of monoclinic zirconia improved from 33MPa to 134 MPa with adding of 50%wt alumina in sintering temperature of 1650°C.

Abstract: The goal of this work is to modify surface of calcium carbonate nanoparticles with silica (CaCO3@SiO2) via sol-gel process, and to investigate the influence of CaCO3@SiO2 on mechanical properties and fracture behavior of poly(lactic acid) nanocomposite. Modified CaCO3@SiO2 nanoparticles were prepared with different Si/Ca ratios. It is found that the Si:Ca wt% ratio was increased with respect to the Si:Ca mole ratio used in the reaction. Incorporating CaCO3@SiO2 of 5 wt% increased elastic modulus, %elongation at break and notched impact strength of PLA nanocomposites, which these properties of CaCO3@SiO2-PLA nanocomposite was increased with respect to increasing of SiO2 content on the surface of CaCO3 nano-particles. This implies that better compatibility between polymer matrix and filler was achieved after modification surface of CaCO3 with SiO2 layers.

Abstract: Portable bridges are very important for maintaining mobility in the aftermath of natural disaster or in the battlefield. This requirement has lead to the needs for light-weight bridging system for ease in launching, retracting, transporting, and storing. In this research, a foldable bridge with three sections of beam connected together using the hinges connection has been designed and analyzed. The bridge is constructed using sandwich Carbon Fiber Reinforced Polymer (CFRP) which consists of CFRP and Aluminum Honeycomb, as the skin and core, respectively. The uses of materials are expected will reduce the total weight of bridge without decreasing of overall performance. Failure theories of composite material such as Maximum Stress, Maximum Strain, Tsai-Wu and Tsai-Hill failure theories were selected to generate an allowable strength graph. From the graph, can be seen that, the material stresses are in the allowable stress-strain ranges, therefore, the bridge is capable of carrying the design load with sufficient safety factor.

Abstract: Externally pressurized thin-walled GFRP composite cylindrical shell strength was studied against failure. Fiber breakage, matrix breakage, interlaminate shear deformation, delamination shear deformation and micro buckling failure were investigated employing maximum failure criteria as volumetric fiber fraction factor varied. One-ply cylindrical shell with fiber angle orientation of 0 degree was modeled in ABAQUS finite element simulation and the result was varied using analytical approaches. Moreover, the pressure fluctuations for various volumetric fiber fraction factors were quadratic according to plotted graphs obtained. Meanwhile, MATLAB software was used for theoretical analysis. The comparison of two approaches was proved to be accurate. Subsequently, failure strength of various laminated GFRP cylindrical shell with different fiber angle orientations at each ply was studied for diverse volumetric fiber fraction factors. Stacking sequence, fiber angle orientations were mainly effective on failure strength.

Abstract: The power loss in laminated transformer cores is always greater than the nominal loss of the electrical steel laminations, by a factor known as the building factor. This paper discussed result of an investigation towards the effect of using two different Grain-Oriented Silicon Iron (3%SiFe) materials to the 100kVA three phase distribution transformer. The thicknesses of the material that have been used in this research are 0.23mm and 0.27mm. The transformer core will be assembled with 60o T-joint with 5mm mitred corner overlap length. Power loss has been measured using no-load test with 29 layer of lamination while nominal loss measured using Epstein test frame. At the operation mode flux density, 1.5T, the building factor of the transformer model core material with 0.23mm thickness is 1.219 while with the building factor for 0.27mm thickness is 1.250. This shows that thinner transformer core lamination is better than the other one by 2.5% during operation mode.

Abstract: Cylindrical vessels are widely used for storage and transportation of fluids. Using composites shells can improve the corrosion resistance of the product and reduce weight therefore investigation of the mechanical behavior is important. For this purpose cylinders with 6, 12 and18-ply of GFRP , with symmetric ply sequence of [90/0/90]s, [90/0/90/0/90/0]s and, [90/0/90/0/90/0/90 /0/90]s with layer thickness 1.3 mm and mean radius 250 mm, are considered under uniform radial patch load. The analysis was based on the shell theory and classical mechanics of laminated composites. A code was written using MATLAB software to compute stress and deflection of the cylinder shell. In numerical simulation, each unidirectional composite ply is treated as an equivalent elastic and orthotropic panel. Analysis is focused on the area of cylinder where the patch load is applied. The results show that the analytical prediction compares well with numerical responses of previous literature. The procedure can be used to predict maximum stress and displacement in a multi-layer shell for various types of similar loading.