Key Engineering Materials Vols. 471-472

Abstract: Increasing utilization of thermoplastic composites in the structural application necessitates understanding of damage tolerance characteristics. In this work, unreinforced, 20 % short, 20 % long glass fiber reinforced polypropylene were injection molded and considered. Test specimens with different notch sizes were tested under static as well as fatigue loading conditions. Under static load condition, short fiber reinforced and unreinforced test material exhibited notch strengthening effect; whereas long fiber reinforced material exhibited notch weakening effect. Failure morphology under fatigue condition exhibited the influence of notch size and length of reinforced fibers over performance. Significant difference between notched and unnotched specimens is observed at low cycle fatigue and very less difference in performance is observed at high cycle fatigue condition.

Abstract: Composite cathodes made of perovskite La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) and SDC carbonates (SDC-(Li/Na)2CO3) were investigated in relation to their structure, morphology, thermal expansion coefficient and porosity. As a first step, the LSCF powder was prepared by sol-gel technique. This was followed by the preparation of the LSCF-SDC carbonates composite cathode by mixing the LSCF with SDC-(Li/Na)2CO3 electrolyte via solid state reaction in various compositions, i.e. 30, 40 and 50 wt.%, namely 70LSCF-30SDC7030, 60LSCF-40SDC7030 and 50LSCF-50SDC7030, respectively. The powder mixtures were then calcined at 680oC. The resultant powder was fine with surface area of about 3.39-7.42 m2/g and particle size of 0.56-0.66µm. The powder consists of two distinct phases, i.e. LSCF and SDC-(Li/Na)2CO3 as confirmed with x-ray diffraction. The microstructures were observed under scanning electron microscopy (SEM). Increasing the amount of the SDC-(Li/Na)2CO3 electrolyte in the composite cathode was found to bring the thermal expansion of the cathode closer to that of the electrolyte. The cathode pellets were later compacted at different pressures (27, 32 and 37 MPa) and sintered at 600oC. The optimum porosity (20.99-24.98%) was achieved for samples with SDC-(Li/Na)2CO3 content of 30-50% sintered at 600oC and cold pressed at 37 MPa.

Abstract: The important effect of yoghurt on people's health caused increasing of many technological works and researches not only in our country but also all over the world.The environment in which yoghurt kept, may cause many sort of germs and contamination paths by the effects of some factors which are fairly similar to its own structure. These factors change the shelf-life of yoghurt and finally cause spoilage in yoghurt. In this context, it is known that the scientific works in this area which are aiming to minimize this spoilage effect, focus on the yogurt structure and packaging of yoghurt. The aim of this paper is to improve a smart polymer material which interacts with serum and changes color of the package by considering serum occurring within the shelf-life of yoghurt. PP based material will be used with the biological agencies like “kaoline” and “talc” and implemented mainly or superficial, the color change will be arised if the serum's PH increases. In practice, everyone can see the color changes with the window which will be placed on the label and the window will include the cautions according to the color levels.

Abstract: Increasing worldwide environmental awareness is an encouraging scientific research into the development of cheaper, more environmentally friendly and sustainable construction and packaging materials. Kenaf fibre is a natural fibre which is growing in popularity due environmental issues and its properties as filler. Epoxy is a versatile thermosetting polymer which has a low curing temperature and used in making carbon fibre and glass composites. In this paper the properties of kenaf bast fibre epoxy reinforced composite have been investigated. The effects of alkali surface treatment of the fiber on the composite properties are also investigated. A hand layup method was use to fabricate the test specimens. Generally, all the treated fibre composites performed better than the untreated fibre with an improvement approximately 5% to 10%. Epoxy has the highest tensile strength and flexural strength among all specimens. The 24wt% treated kenaf fibre composites has the highest tensile strength, 27.72MPa and flexural strength, 56.91MPa. The kenaf fiber weight fraction of 40% gave the highest impact strength. The impact strength of the 40wt% kenaf fiber increased 14.3% after alkali treatment.

Abstract: Polypropylene- layered silicate nanocomposite based on muscovite was prepared via melt compounding. Muscovite was organomodified with cetyltrimethylammoniumbromide (CTAB) by using different filler loading. The effects of muscovite content on mechanical and morphology properties were evaluated. Analysis of test data showed that the mechanical properties increased with an increase in filler loading up to a threshold of 3 wt%; thereafter the material properties were degraded. The enhancement of properties attributed to the formation of intercalated and exfoliation nanocomposite structure at these loadings of clay. At higher filler loading, degradation in mechanical properties maybe attributed to the formation of agglomerated clay tactoids.

Abstract: Ni-P/nano- SiC composite coatings were deposited in different concentrations of SiC nano-particles in the bath. The hardness and corrosion resistance of the composite coatings with different content of SiC nano-particles were measured. Moreover, the structure of the composite coatings was investigated by means of X-ray diffraction (XRD), while their morphologies and elemental composition were analyzed using scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). Results showed that co-deposited SiC nano-particles contributed to increase the hardness but corrosion resistance of electroless Ni-P coatings decreased due to agglomeration of nano-particles and increasing porosity of coatings.

Abstract: The objective of this work is to investigate the influence of LDH loading on the thermal stability and thermal degradation kinetics of the PP/Ni-Al LDH nanocomposites using thermogravimetric analysis (TGA) and to compare the results with that of the neat PP. For this, Ni-Al LDH was first prepared by co-precipitation method at constant pH using their nitrate salts and subsequently organically modified using sodium dodecyl sulphate (SDS) by regeneration method. A series of novel PP/Ni-Al LDH nanocomposites was then prepared with various amounts of LDH by melt intercalation method. The XRD results confirm the formation of exfoliated PP/LDH nanocomposites. PP/LDH nanocomposites exhibit enhanced thermal stability relative to the neat PP due to the presence of barrier effect of LDH lamellar layers and the thermal stability of the nanocomposites also increases with increase in the LDH loading. When 10% weight loss is selected as a point of comparison, the decomposition temperature of PP/LDH (5 wt %) nanocomposite is 15 oC higher than that of neat PP. The thermal degradation activation energy of the nanocomposites is determined via Coats-Redfern method and compared with that of neat PP. The improvement of thermal stability of PP nanocomposites is also confirmed by increasing the activation energies (Ea) and the integral procedural decomposition temperature (IPDT) compared with neat PP. Criado method is finally used to determine the degradation reaction mechanism of various samples.

Abstract: The capability of structures to absorb as much amount energy, particularly in automotive structures to reduce the damages due to impact energy during collision attract attention of many reserachers. During the actual collision, the crash box is not only experienced axially crash, but also in oblique crash. In this study, an experiment was carried out to study the crashworthiness parameters and behaviour of pultruded fibre E-glass/polyester pultruded composite tubes under oblique loading. Quasi-static loadings were applied axially and oblique on the pultruded composite to investigate the response of force-displacement during progressive collapses. The pultruded wall thickness of 6 mm tubes were used and four oblique angles of 0˚, 5˚, 10˚ and 15˚ were selected to study their effect on crushing behaviours and collapse modes using compression moulding. All specimens were chamfer 45˚ on top end for purpose to work as a collapse trigger mechanism. The results showed that the energy absorption of the structures increasing with decrease of the loading angle.

Abstract: Artificial neural networks (ANN) and polynomial classifiers (PC) have been successfully used to predict the fatigue failure of fiber reinforced composite materials. This includes predicting the behavior of the same material subjected to different loading conditions as well as predicting the fatigue behavior of different materials. In this work, the fatigue life prediction obtained using both methods will be compared. The effect of the various parameters influencing the prediction will be presented and the advantages and disadvantages of each of the methods will be discussed.

Abstract: A hybrid composites mechanical properties consisting of un-treated and treated bast Kenaf fiber and E- glass fiber was investigated by varying the fiber glass weight ratio and using interplay fabrication method. A further comparison was made with corresponding properties of 100% wt E-glass fiber composites sample. The expected results were to have better composites performance in terms of toughness and impact strength as a comparison between the E- glass fiber reinforced composites and Kenaf fiber reinforced composites alone. All samples are prepared using typical samples preparation techniques. Result shows that the incorporation of E – glass fiber resulted in brittle failure and a higher amount of E-Glass fiber with low percentage of Kenaf fiber resulted in high strength, low ductile and low toughness behavior.