Current Trends in Materials Engineering II

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Authors: Ai Ling Pang, Hanafi Ismail, Azhar Abu Bakar
Abstract: The effect of untreated and treated (chromium sulfate and sodium bicarbonate) kenaf (KNF) on the water uptake and morphological properties of linear low density polyethylene/poly(vinyl alcohol)/kenaf (LLDPE/PVOH/KNF) composites was studied. The composites were prepared by using an internal mixer (Haake Polydrive) at 150 °C and 50 rpm for 10 min. The results showed that the untreated composites tend to absorb greater amount of water compared to the treated composites. This shows that the chromium sulfate and sodium bicarbonate treatment on KNF had improved the interfacial adhesion between KNF and LLDPE/PVOH matrices. Consequently, the capability of water absorption by the treated composites was reduced. Scanning electron microscope (SEM) result shows that lesser traces of filler pull-out and better filler-matrix interfacial adhesion were observed in the tensile fractured surfaces of treated composites.
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Authors: Nur Dalilah Johari, Zulkifli Mohd Rosli, Jariah Mohamad Juoi, Muharniza Azinita Musa
Abstract: Brookite is the least known titanium dioxide (TiO2) crystallographic phases compare to anatase and rutile. In a sol-gel process, very few works are devoted on synthesizing pure brookite as a thin film coating and usually brookite co-exist with anatase and rutile as a byproduct. This study is performed as an attempt to produce brookite thin film coating via sol-gel dipping method. In this study, the influence of catalyst type on TiO2 phases, morphology and grain size were investigated. Hydrochloric acid (HCl) is used for an acid catalyst and sodium hydroxide (NaOH) is used as base catalyst. All of the TiO2 films were deposited on a glass substrate and heated at four different temperatures of 400°C, 450°C, 500°C and 550°C for 3 hours. X-ray diffraction (XRD) is employed to analyze the phases and the grain size acquired. Images on the surface morphology are obtained with Scanning Electron Microscope (SEM). Results showed that brookite phase exist only for base catalyst with a grain size of 27.40 nm for all of the selected temperatures except at 550°C. SEM results revealed that the surface morphology of the deposited TiO2 film with base catalyst comprised of agglomerated particle networks. In contrast, the surface morphology of the deposited TiO2 film with acid catalyst seems more compact and uniform with an XRD pattern of amorphous-like characteristic having grain size of less than 3 nm.
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Authors: Pei Gie Gan, Sung Ting Sam, Muhammad Faiq bin Abdullah, Nik Noriman bin Zulkepli, Yin Fong Yeong
Abstract: In recent years, there has been a great interest in the production of nanocrystalline cellulose (NCC) due to its excellent properties. In this study, empty fruit bunch (EFB) was used as the material for the production of NCC due to its high cellulose content, inexpensive and readily-available source. NCC was prepared using acid hydrolysis at 62% for 1 hours. The morphology of NCC was determined by Field Emission Scanning Electron Microscopy (FESEM). The size of NCC was less than 50 nm in width. The obtained NCC was also characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). FTIR spectra analysis showed that hemicellulose and lignin were mostly removed from the EFB after bleaching and alkaline pre-treatment. XRD diffractograms revealed that EFB nanocellulose showed a crystallinity improvement of 24.3% compared to raw EFB cellulose.
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Authors: Norazman Farhaneem, Sian Meng Se, Mohd Fairuz Dimin, Azizah Shaaban
Abstract: Biochar was derived from the crop residue as multifunction materials for agriculture purposes and a soil amendment to improve soil fertility. Rubber wood sawdust (RWSD) was heated slowly inside the vertical furnace for an hour at temperatures ranging from 300 °C to 700 °C. The aim of this study is to investigate the influence of pyrolysis temperatures on the physiochemical properties of the biochar. The properties of biochar were characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM) attached with Energy Dispersive X-ray for elemental analysis. It was found that pore size distribution was more uniform on samples heated at higher temperature (700 °C). The SEM-EDX analysis confirmed the O:C ratio was directly proportional to the heating temperature. These means that slow pyrolysis of RWSD at 700 °C could produce biochar of greater cation exchange capacity (CEC) that important for soil fertility improvement.
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Authors: Kim Song Tan, Azira Aziz, Kok Lang Mok, Hui Mei Lim, Roslim Ramli
Abstract: Evaluation of Natural rubber (NR)/graphene composite was performed using a transmission electron microscope (TEM). As a comparison, plain NR and graphene were also prepared and viewed under the same conditions. The NR and composite material were swelled in styrene, hardened by polymerization process, sectioned into lamellar at room temperature and stained by osmium tetroxide before viewing. As osmium reacts with alkenes in NR but not with polystyrene, a good contrast between the two materials can be achieved. We report TEM images of all the materials used in this study and how TEM images can be employed to relate the interaction between NR particles, with and without the presence of graphene. No obvious interaction between NR and graphene was observed in the composite sample but interparticle interactions between NR particles can be clearly seen. However, the increase in distance between NR particles, as observed in the swelled NR/graphene composite film, is an indication of lesser interparticle interactions. This observation explains the ineffectiveness of graphene as filler in NR, under the current preparation process.
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Authors: Najwa binti Hamzan, Muhammad Firdaus Omar, Huang Nay Ming, Boon Tong Goh
Abstract: Well-aligned NiSi/SiC core-shell nanowires were grown on Ni-coated p-type crystal Si (100) substrates by using hot-wires chemical vapor deposition (HWCVD) technique. The growth of the nanowires was performed at a substrate temperature of 450°C and facilitated by a hot-filament at a temperature above 1800°C. Electron microscopy characterizations were employed to investigate the morphology, and microstructure properties of the nanowires. A high-resolution transmission electron microscopy (TEM) images indicate that the nanowires were structured by single crystalline NiSi and amorphous SiC as the core and shell respectively. Moreover, the TEM images showed presence of 3C-SiC nano-crystallites embedded within an amorphous matrix in the shell.
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Authors: Mat Taib Razaina, Cho Yin Tham
Abstract: Isothermal crystallization kinetics and morphology of Poly (lactic acid) (PLA) and PLA/ethylene acrylate copolymer (EAC) blends were studied by differential scanning calorimetry (DSC) and polarized optical microscopy (POM) at various temperatures (95–125°C). The DSC data obtained was analyzed using the Avrami equation. The crystallization rate was found to depend on the crystallization temperature (Tc) and EAC content. At a given Tc, the crystallization rate value was greater in the blends than in PLA suggesting that the presence of EAC enhanced crystallization of PLA. Based on the DSC analysis the crystallization rate was maximum when PLA blend with 1 wt.% EAC was isothermally crystallized at 103°C. The presence of EAC did not significantly change in the spherulitic growth rate (G) of PLA. Analysis of the growth rates using the Lauritzen-Hoffman theory showed that a regime II to regime III transition was present for all PLA/EAC blends and that this transition occurred at temperature of 100°C. The fold surface energy values of PLA/EAC blends were lower than that of PLA indicating that PLA chains can readily fold onto the crystal nucleus surface after the incorporation of EAC.
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Authors: Nurul Farhana Ibrahim, Hasmaliza Mohamad, Siti Noor Fazliah Mohd Noor, Nurazreena Ahmad
Abstract: Hydroxyapatite (HA) has similar constituent with natural bone mineral and is able to evoke apatite formation on the bone interface. Similarly, bioactive glass (BG) such as 45S5 has the ability to induce bone formation when exposed to physiological environment. However, both materials have drawbacks in mechanical properties such as brittleness and low compressive strength. Hence, HA-BG composite has potential for enhance properties. The current work aims to assess the effects of BG addition in HA system focusing on mechanical properties.
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Authors: Joshua Zheyan Soo, Bee Chin Ang, Boon Hoong Ong
Abstract: Titanium dioxide (TiO2) is a suitable material to be used in the field of photocatalytic water treatment. In this research, TiO2 membrane fibers were synthesized using a combination of non-aqueous sol gel method and electrospinning technique. Titanium isopropoxide (TTIP) was used as the precursor for the TiO2 filler of the fibers. Both polyvinylpyrrolidone (PVP) and polyvinylidene fluoride (PVDF) were used as the polymer base to obtain the respective membrane fibers. The effects of weight concentration of TTIP as well as the type and molecular weight of the polymer on the morphology of the fibers were studied. Microscopic characterization using field-emission scanning electron microscopy (FESEM) and Energy Dispersive X-Ray (EDX) analysis was performed to obtain the morphology and elemental composition of the fibers. Sub-micron range fibers with a continuous network were generally obtained. Fibers that are subjected to post-electrospinning calcination have a lower fiber diameter. Polymer decomposition is shown to occur during calcination which yielded higher purity TiO2 fibers. The use of higher molecular weight polymers can produce a stronger fibre network for membranes.
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