Advanced Materials Research Vol. 576

Abstract: The effects of milling speed and calcinations temperature towards La0.6Sr0.4CO0.2Fe0.8O3-δ-SDC carbonate (LSCF-SDC carbonate) composite cathodes were investigated. The preparation of samarium-doped ceria (SDC) carbonate was firstly done by milling the SDC nanopowder with carbonate using the high-energy ball milling (HEBM) in air at room temperature. The obtained SDC carbonate was then used to mill with composite powder of lanthanum strontium cobalt ferrite (LSCF) which is one of the promising materials for the cathode of solid oxide fuel cells (SOFC). The purpose of milling LSCF composite powder with SDC carbonate was to get new composite cathode for intermediate-to low-temperature solid oxide fuel cells (IT-TLSOFC). LSCF composite powder with SDC carbonate was milled using high-energy ball milling with milling speed of 150 rpm and 550 rpm and calcinations temperatures of 750°C, 800°C, 850°C and 900°C. Field emission scanning electron microscopy (FESEM) analysis revealed the presence of large particle resulting from the increasing of calcinations temperature. FESEM also shows the particle size decrease in size with the increasing of milling speed. Therefore, the speed of 550 rpm and temperature of 900°C were found to be the best milling speed and calcinations temperature in producing the composite cathode of LSCF-SDC carbonate.

Abstract: Polylacticacid (PLA), produced from annually renewable, natural resources is a potential candidate for the partial replacement of petroleum based polymers and also for its biodegradability. PLA is well known for its better mechanical, thermal property but unfortunately the brittleness and rigidity limit its applicability. For a great number of applications such as packaging, fibers, films, etc., it is of high interest to formulate new PLA grades with improved flexibility and better impact properties. In order to develop PLA-based biodegradable packaging, the physico-mechanical properties of commercially available PLA should be modified using plasticizers. For this, PLA was melt-mixed with poly ethylene glycol (PEG) of 600 molecular weights by twin screw extruder. The thermal properties of plasticized PLA were characterized by utilization of dynamic mechanical analysis. The result shows that with addition of plasticizer glass transition temperature (Tg) is decreased sharply and the storage modulus was also decreased.

Abstract: Over the last three decades, most of the efforts in mechanics of materials science have been focused to develop tougher and stronger ceramics via cost effective processing techniques. In the present work, 3 mol % Yttria-stabilized tetragonal zirconia (3Y-TZP) composites with 25 wt. % of ZrB2 was prepared by pressureless sintering method in argon atmosphere over the temperature range of 1350-1550°C for one hour holding time. The influences of zirconium diboride addition in the zirconia matrix, as well as the sintering temperature, on the densification, phase stability and electrical properties of sintered samples have been studied. The results revealed that electrical resistivity values is very low (high electrical conductivity) when 25 wt. % of ZrB2 is incorporated to pure 3Y-TZP.

Abstract: World is currently focusing on alternate material sources that are environment friendly and biodegradable in nature. Due to the increasing environmental concerns, bio-composite made from natural fibers and polymeric resin, is one of the recent developments in the industry and constitute the present scope of experimental work. This work presents on advantages, mechanical and physical behavior of jute fiber – epoxy composites, one of the renewable alternatives. The bio-composite is experimentally investigated in term of low velocity impact loading. The experimental observations in term of damage mechanism, maximum force and maximum energy absorption were studied to understand the effect of fiber orientation. A comparative study with typical synthetic fibers like carbon and glass were also conducted.

Abstract: Thermoplastic polyurethane (TPU) nanocomposites were prepared using polycaprolactonediol as the soft segment, 4,4’-diphenylmethane diisocyanate as the hard segment, 1,4-butanediol and palm oil polyol. Nanoclay with certain weight percent (wt%) was reinforced as filler to improve both mechanical and shape memory behavior of the nanocomposites. Palm oil polyol was introduced in order to provide hyperbranched structure for better dispersion of filler in the matrix as well as aiding the crosslinking process. The experimental results showed that the mechanical and shape memory behavior of clay reinforced polyurethane nanocomposites were influenced by clay weight percent in the polymer matrix. TPU with 3 wt% clay showed optimum values of mechanical properties while the shape memory behavior decreases with increasing clay content.

Abstract: Barium hexaferrite BaFe12O19 (BHF) is one of the great importance as permanent magnets, particularly for recording magnetic in microwave devices. Nanocrystalline BHF powders were prepared by sol gel auto combustion method in citric acid – metal nitrates system. Hence the mole ratios of Ba2+/Fe3+ were varied at 1:12; 1:11.5 and 1:11 and with pH of 7 in all cases using amonia solution. For final formation of nanocrystalline BHF, heating process was done at 850oC for 10 hours in all mol ratios of Ba2+/Fe3+. The nanocrystallite size was calculated from broadening X Ray Diffraction (XRD) peaks using Scherrer formula. XRD data shows that BHF of ratio 1:12 has the same diffraction pattern with the ratio of 1:11 especially at higher value of 2 θ. Diffraction pattern of BHF with the ratio of 1:11.5 was fitting in exactly to the standard searching match and the highest value of best Figure of Merit (FoM) is 90% with the crystallite size of 22 nm. The best FoM and crystallite size for ratio of 1:12 and 1: 11 are 88% and 56 nm respectively. The diffraction peaks of BHF with the ratio of 1:12 and 1:11 are in the right side from of 1:11.5 since the amount of impurity of both is higher (12%) than of BHF with the ratio of 1:11.5 (10%).

Abstract: Kenaf (Hibiscus cannabinus.L) is a crop- that produces about 70% of biomass larger than any of forest plantations. There is no specific way of using kenaf biomass in industry instead for animal feed and burning in various forms (waste in general). As a result, several researches had been conducted to utilize it in the production of biodegradable polymer as well as bioethanol. This is due to its complex cellulose content that is useful to be converted into glucose before further process. The conversion step from cellulose content of kenaf biomass into glucose is known as pre-treatment process. In this paper, dilute acid hydrolysis was chosen as the pre-treatment process. With the aim to evaluate the maximum percentage of glucose conversion for this kind of pre-treatment process from kenaf biomass, statistical analysis which is analysis of variance (ANOVA) design via central composite design using response surface method (RSM) was selected. Thus, the lower the mass which is at 2 g, and at higher temperature which is 180 oC in longer time which is in 60 min results about 25.33% glucose conversion with the comparison of the predicted value obtained from the experimental design.

Abstract: Lactic acid (LA) is commercially produced biologically using food-derived raw materials such as potato and corn. It seems to be less economical since they have to compete with the food sources industries. Thus, kenaf (Hibiscus cannabinus) is found to be the best alternative to substitute the raw material for LA production. In this paper, kenaf core were used as the substrate for production of LA by Rhizopus oryzae FTCC 5215. Since kenaf is one type of lignocellulosic material which is naturally resistant to breakdown to its structural sugars, it will inhibit microorganisms to be accessed through. Thus, hydrolysis process is needed as the aid for the liberation glucose. The highest value of lactic acid produced is 15.2 g/L at 25 oC with speed 200 rpm.

Abstract: The current study is to examine the effect of ultrasonication on the synthesis of forsterite (Mg2SiO4) powder. Ultrasonication and ball milling were performed using talc and magnesium oxide as starting precursors, followed by heat treatment to obtain forsterite. The X-ray diffraction results of the powders heat treated at 1200°C showed that the 2 hours ultrasonication followed by 3 hours ball milling was beneficial in retaining the forsterite phase in the matrix. The results were similar to ball milling for 10 hours prior to heat treatment. The derived powders also exhibited very fine crystallite size in the range of 28 to 35 nm thus indicating the viability of using ultrasonication as part of the processing steps in the synthesizing of forsterite ceramics.

Abstract: This paper reports the improvement in tensile strength of epoxy by using binary hybrid nanocomposites of nanoclay and multi-wall carbon nanotube using a solution casting method. The effect of clay/MWCNT ratio, types of solvent, clay cation, composition of LENR, cure time and cure temperature on the tensile properties of epoxy nanocomposites were investigated using Taguchi Method. Orthogonal array L27 is chosen for sample preparations. Analysis of Mean (ANOM) and Analysis of Variance (ANOVA) was used to identify the dominant factors and the optimum values of clay/MWCNT ratio and settings of other process parameters. Confirmation of experiment was performed with the optimum parameter settings and the measured mechanical properties were compared with the predicted results. Morphologies of the fracture surface of MWCNT/epoxy nanocomposites was observed by scanning electron microscope (SEM). Transmission electron microscope (TEM) and X-ray diffraction (XRD) test were employed to analyse the dispersion structure in the modified samples.