Applied Mechanics and Materials Vol. 606

Abstract: Resist patterning method has been used to enable selective ZnO nanorods grown via facile hydrothermal process. The growth region of the ZnO nanorods was controlled by pre-coating the seed layer on the Silicon base substrate. Using the plasma process, the seed layer which is not coated with a resist layer will be etched out. Therefore, when the samples completely undergone the hydrothermal process, there will be no nanorods grow in that specific area. The grown ZnO nanorods was in well array with flat hexagonal tip and wurtzite crystal structure. This technique is can be applied for application which require integration of nanostructure in specific critical areas such as an interdigitated electrodes (IDE) for various gas sensor applications.

Abstract: Magnesium alloys are the very progressive materials whereon is due to improve their end-use properties. Especially, wrought Mg alloys attract attention since they have more advantageous mechanical properties than cast Mg alloys. Investigations were carried out the effects of heat treatment on tensile strength and microstructure of AZ61A magnesium alloy. The AZ61A Mg alloy is solution heat treated at the temperature of 650⁰F (343°C) for various soaking timing such as 120 min, 240 min and 360 minutes and allowed it cool slowly in the furnace itself. Magnesium alloys usually are heat treated either to improve mechanical properties or as means of conditioning for specific fabrication operations. Special attention had been focused on the analysis of mutual relations existing between the deformation conditions, microstructural parameters, grain size and the achieved mechanical properties. The result after the solution heat treatment, showed remarkably improved hardness, tensile strength and yield strength. It would be appropriate for a forming process namely isostatic forming process.

Abstract: The newly developed non-woven filter media are composed of randomly oriented fibrous fibers from lignocellulosic biomass. The aim of this study is to investigate the feasibility of incorporating chitosan solution in fibrous filter media made from lignocellulosic biomass. The wet lay-up method was adopted for filter media fabrication. Diluted acetic acid was used as medium to dissolve the chitosan powder. Chitosan solution was applied to the fiber using two different deposition techniques, namely, spray method and addition method. The tensile test demonstrated that the filter media using spray method outperformed a filter media made from by addition technique. From the FT-IR spectrum, when the chitosan was added to empty fruit bunches fibers, the absorption peaks at around 1642 cm^-1 are clearly identified that showing the presence of amine group in the fibers. The changes observed in the spectra indicated the possible interaction of functional groups between chitosan and cellulose in the fibers. The newly developed non-woven filter media integrates the functions for both the deep filtration and mechanical screen, thus it will be an alternative medium in oily wastewater treatment industry.

Abstract: Low Density Polyethylene was blended with various contents of tapioca starch (10%, 20%, 30%, and 40%) with addition of compatibilizer, i.e. PE-g-MA and cooking oil as plasticizer. The blends were prepared by co-rotating twin screw extrusion process and characterized by melt flow index (MFI) analysis and tensile test. Tapioca starch based polyethylene biofilms were studied in term of biodegradability by fungi test. The increasing starch content to LDPE blend reduced the MFI values and tensile strength but in 30% and 40% of starch content in tensile strength is higher than control LDPE’s strength due to molecular orientation in sample. However, incorporation of PE-g-MA as compatibilizer increases the mechanical properties of starch based polyethylene blends due to the reaction between maleated PE and starch, thus improves adhesion and reduces slippage at matrix-filler interface. The increasing of TS also increase the water content in film sample, weight loss percentage in TGA, and percentage degradation of LDPE/TS blend film.

Abstract: Malaysian agro-industrial sector produces considerable quantity of solid palm waste biomass and potential exploitation of this waste residue is necessary for economic and environmental aspects. The Oil Palm Shell (OPS) waste biomass was subjected to multimode microwave pyrolysis at 2.54GHz with coconut activated carbon layers. The microwave power and N₂ flow rate were varied to investigate its effects on heating profile, product distribution and bio-oil composition using fixed coconut activated carbon loading. The OPS surface and bed temperature, heating rate, pyrolysis product distribution and bio-oil composition was found dependent on microwave power and N₂ flow rate. The highest bio-oil yield of 31 wt% was obtained both at 300W and 600W using 4LPM. The phenol content varied from 34.02-44.42% of GC-MS area with highest value at 300W and 8LPM. Bio-oil from this study also contained 1,1-dimethyl hydrazine of 7.04-13.01 % of GC-MS area.

Abstract: A morphological evolution of the crystals growth has been investigated using two dimensional (2D) multi-phasefield (MPF) simulations. Cementite carbide growth is taken as an example in the present case, while concern is given in simulating the preferred growth orientation of the carbide. In order to evaluate competitive growth between carbide seeds, variations on carbide seed orientation have been implemented. In the present model, variation of the seed orientations are embedded on the interfacial energy, thereby the anisotropy characteristic of interfacial energy can be obtained. Simulation utilized homogenous grain orientation that less than the preferred growth orientation results insignificant grain growths (first case). In the opposite way, simulation utilized homogenous grains orientation that equal or more then the preferred growth orientation, results in the homogenous significant grain growth (second case). On the other hand, simulation utilized heterogenous grains orientation involving grains in the first and second case, results a competition growth that inhibit and diminish the grains in the first case. It can be concluded that the present simulations works can shows the existence of preferred orientation growth during grain growth phenomena including the growth of cementite carbide phase.

Abstract: The use of tetragonal zirconia as a dental restorative material has recently increased because of its unique mechanical and optical properties, as well as high biological compatibility with the oral cavity environment. However, the mechanical properties of zirconia can be severely degraded, which leads to the failure of dental restorations. This review focuses on the low-temperature degradation of dental zirconia and its effects on the properties of zirconia and on the oral environment. The purpose is to show the importance of this negative phenomenon and suggest guidelines for minimizing the aging of zirconia that is used as a dental restoration material.

Abstract: The market share of biodegradable polymers from renewable sources has grown rapidly in the plastic industry. Properties of the polymers from renewable resources can be enhanced through blending and composite formation. Fermented chitin is a by-product in a bacterial prawn waste fermentation for protein recovery which has undergone mild chemical treatment producing treated fermented chitin (TFC). TFC was further acid hydrolysed to produce chitin nanowhiskers (TFCNW). The chitin nanowhiskers was used as filler in polylactic acid (PLA) through solution casting method. Atomic Force Microscopy showed TFCNW particles are uniformly dispersed in PLA matrix but tends to agglomerate as TFCNW loading increased. Tensile strength of the biocomposite film increased up to 12.4 MPa at 2 phr TFCNW which it decreased with further addition of TFCNW. The Young’s modulus increased with increasing of TFCNW content up to 3.69 GPa. However, elongation at break of the biocomposite film decreased by 66 % upon addition of TFCNW when compared to pure PLA.

Abstract: In this research paper phase identification was conducted based on the thermal and microstructural analysis of pure Mg, binary ‎Mg-Ca and ternary Mg-Ca-Zn alloys which have been received significant attention to be used as biodegradable implants. ‎Thermal analysis results show that nucleation temperature of primary Mg decreased and solidification range expanded with ‎adding Ca and Zn to the Mg melt. Moreover, characteristics temperatures of intermetallic phase assess for Mg-1Ca and Mg-‎‎1Ca-3Zn alloys. Microstructural evolutions of specimens were characterized by optical microscopy, scanning electron ‎microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). The result revealed that the identification of Mg₂Ca and Ca₂Mg₆Zn₃ ‎intermetallic phases by thermal analysis which were also detected by EDS. Furthermore with addition of Ca and Zn elements, the ‎coherency time increased while, the fraction of primary α-Mg at dendrite coherency point (f_α^DCP ) decreased.‎

Abstract: Pb(II) which is considered a toxic and common pollutant to the environment was removed from the aqueous solution using the one step photo catalytic reduction with the help of titanium oxide PVA-alginate beads. The photo catalytic reduction was performed in the presence and absence of sunlight at pH 7 and Pb(II) concentration of 50mg/L at the equilibrium contact time of 180 min. The results revealed that the titanium oxide PVA-alginate beads were capable of removing 98% of Pb(II) from the aqueous solution within 150 min. The titanium oxide PVA-alginate beads can be separated from the aqueous solution after photocatalytic process and they can be reused for at least 7 times without significant loss in their initial properties.