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CONTENTS
Volume 3, Number 3, October 2014
 

Abstract
Biocomposites from polypropylene (PP) and corn cob (CC) were investigated. The effect of corn cob content and maleic anhydride polypropylene (MAPP) as compatibilizer were studied. Results showed that addition of corn cob (CC) in PP have decreased the tensile strength and elongation at break, whereas modulus of elasticity of biocomposites increased. The biocomposites with the MAPP as compatibilizer exhibited higher tensile strength and modulus of elasticity compared biocomposites without MAPP. The morphology study of biocomposites indicates that enhanced the interfacial interaction and adhesion between filler and matrix with the presence of MAPP.

Key Words
polypropylene; corn cob; compatibilizer; biocomposites

Address
Salmah H., M.Z. Marliza and E. Selvi: School of Materials Engineering, Universiti Malaysia Perlis, 02600, Jejawi, Perlis

Abstract
Surface enhanced Raman Scattering (SERS) has attracted attention because the technique enables detection of various chemicals, even down to single molecular scale. Among the diverse candidates for SERS substrates, Au nanoparticles are considered promising due to their fine optical properties, chemical stability and ease of surface modification. Therefore, the fabrication and optical characterization of gold particles on solid supports is highly desirable. Such structures have potential as SERS substrates because the localized surface plasmon resonance of gold nanoparticles is very sensitive to combined molecules and environments. In addition, it is well-known that the properties of Au nanoparticles are strongly dependent on their shape. In this work, arrays of shape-controlled Au nanoparticles were fabricated to exploit their enhanced and reproducible optical properties. First, shape-controlled Au nanoparticles were prepared via seed mediated solution-phase synthesis, including spheres, octahedra, and rhombic dodecahedra. Then, these shape-controlled Au nanoparticles were arranged on a PDMS substrate, which was nanopatterned using soft lithography of poly styrene particles. The Au nanoparticles were selectively located in a pattern of hexagonal spheres. In addition, the shape-controlled Au nanoparticles were arranged in various sizes of PDMS nanopatterns, which can be easily controlled by manipulating the size of polystyrene particles. Finally, the optical properties of the fabricated Au nanoparticle arrays were characterized by measuring surface enhanced Raman spectra with 4-nitrobenezenethiol.

Key Words
gold; polystyrene particle; PDMS; nanoparticle array; SERS

Address
Seon Mi Shin: Chemicals R&D Center, SK Chemicals, 310, Pangyo-ro, Bundang-gu, Seongnam-si,
Gyeonggi-do 463-400, Republic of Korea

Kyeong Woo Choi, Seong Ji Ye, Young Yun Kim and O Ok Park: Department of Chemical and Biomolecular Engineering (BK21+ graduate program), Korea Advanced Institute for Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of KoreaEgypt


Abstract
Geopolymer composites reinforced with different layers of woven flax fabric are fabricated using lay- up technique. Mechanical properties, such as flexural strength, flexural modulus and fracture toughness of geopolymer composites reinforced with 2.4, 3 and 4.1 wt% flax fibres are studied. The fracture surfaces of the composites are also examined using scanning electron microscopy. The results show that all the mechanical properties of the composites are improved by increasing the flax fibre contents. It is also found that the mechanical properties of flax fabric reinforced geopolymer composites are superior to pure geopolymer matrix. Micro-structural analysis of fracture surface of the composites indicated evidence of various toughening mechanisms by flax fabrics in the composites.

Key Words
geopolymer composite; flax fibre; mechanical properties

Address
Hasan S. Assaedi, Thamer S. Alomayri and It-Meng Low: Department of Imaging & Applied Physics, Curtin University, GPO Box U1987, Perth, WA 6845, Australia

Thamer S. Alomayri: Department of Physics, Umm Al-Qura University, Makkah 21955, Saudi Arabia.

Faiz U.A. Shaikh: Department of Civil Engineering, Curtin University, GPO Box U1987, Perth, WA 6845, Australia

Abstract
In this study, fatigue properties and crack growth characteristics of a polycarbonate (PC) were examined during cyclic loading at various mean stress (amp) and stress amplitude (mean) conditions. Different S vs. N and da/dN vs. K relations were obtained depending on the loading condition. The higher fatigue strength and the higher resistance of crack growth are seen for the PC samples cyclically loaded at the higher mean stress and lower stress amplitude due to the low crack driving force. Non-linear S – N relationship was detected in the examination of the fatigue properties with changing the mean stress. This is attributed to the different crack growth rate (longer fatigue life): the sample loaded at the high mean stress with lower stress amplitude. Even if the higher stress amplitude, the low fatigue properties are obtained for the sample loaded at the higher mean stress. This was due to the accumulated strain energy to the sample, where severe plastic deformation occurs instead of crack growth (plasticity-induced crack closure). Shear bands and discontinuous crack growth band (DGB) are observed clearly on the fracture surfaces of the sample cyclically loaded at the high stress amplitude, where the lower the mean, the narrower the shear band and DGB. On the other hand, final fracture occurred instantly immediately after the short crack growth occurs in the PC sample loaded at the high mean with the low amp, i.e., tear fracture, in which the shear bands and DGB are not seen clearly.

Key Words
polycarbonate; Loading condition; Fatigue strength; Crack growth rate;Failure characteristic

Address
Mitsuhiro Okayasu, Kei Yano and Tetsuro Shiraishi: Department of Materials Science and Engineering, Ehime University 3 Bunkyo-cho, Matsuyama, Ehime, 790-8577, Japan

Abstract
Natural rubber bound phenolic antioxidant, 2,6-di-tert-butyl-4-vinylphenol (2,6-DBVP), was prepared from natural rubber and 2,6-DBVP in both solution and melt state. The 2,6-DBVP had been synthesized from 3,5-di-tert-butyl-4-hydroxybenzaldehyde and methyltriphenylphosphonium iodide (MePPh3I) by Wittig reaction (0oC for 2 hrs, N2 atmosphere). The conditions for preparation of natural rubber bound 2,6-DBVP (NR-DBVP) were optimized for both solution state (1 phr BPO and 8 phr 2,6-DBVP at 70oc for 2 hrs) and for melt state (1 phr BPO and 8 phr 2,6-DBVP at 70

Key Words
natural rubber; phenolic antioxidant; 2, 6-di-tert-butyl-4-vinylphenol; competibilizer; thermoplastic vulcanizate

Address
Pairote Klinpituksa: Department of Science, Faculty of Science and Technology, Prince of Songkla University, Pattani, 94000 Thailand

Anyarat Kiarttisarekul and Azizon Kaesaman: Department of Rubber Technology and Polymer Science, Faculty of Science and Technology, Prince of Songkla University, Pattani, 94000 Thailand


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