•Tungstated zirconia used for conversion of S. obliquus lipids.•Tungstated zirconia showed 94.58% FAME conversion and reuse up to 3 batches.•Heterogeneous catalyst showed comparable conversion with ...homogeneous catalyst.•Heterogeneous catalyst showed higher conversion than enzyme catalyst.•Time requirement for tungstated zirconia catalysis was lowest.
Downstream step of catalytic conversion is scarcely investigated area in microalgal biodiesel production process. In this study a heterogeneous acid catalyst, tungstated zirconia (WO3/ZrO2) is evaluated for conversion of S. obliquus lipids. Catalytic efficiency of tungstated zirconia catalyst was compared to the homogeneous acid catalyst and enzyme catalyst in terms of conversion efficiency, reaction parameters, energy consumption and reusability. Tungstated zirconia catalyst showed maximum biodiesel conversion of 94.58% at 100°C temperature, 12:1 methanol to oil molar ratio and 15% of catalyst amount based on oil weight in 3h. Tungstated zirconia showed comparable biodiesel conversion to homogeneous catalyst and higher conversion than the enzyme catalyst. The time requirement for heterogeneous catalyst was lowest, while, the energy consumption was highest among the selected catalysts. Most of the fuel properties of biodiesel synthesized by tungstated zirconia catalyzed conversion of S. obliquus lipids comply with the specifications set by ASTM and EN standards.
Plastics are solid materials where biodegradation happens on the surface. Only the surface is affected by biodegradation while the inner part should not be readily available for biodegradation. Thus, ...at a laboratory level, the biodegradation rate is expected to be a function of the surface area of the tested sample. The higher the surface area, the higher the biodegradation rate, all other environmental conditions being equal. In order to further explore the role of particle size on biodegradability, plastic pellets of polybutylene sebacate were milled and sieved into different particle sizes, thus obtaining four samples, pellets included, with different specific surface areas (33, 89, 193, and 824 cm2g-1). The surface areas were assessed through direct measurement (pellets) or a theoretical estimation followed by an image analysis. The different samples were tested for biodegradation in soil for 138 days. The rates calculated with a linear regression in the first part of the biodegradation process were related to the respective total available surface area. The data are well described by a linear regression of the double reciprocal plot (the Lineweaver-Burk approach used in enzymatic kinetics) that enables the estimation of the theoretical maximum biodegradation rate (kmax = 97 mg Cpolymer day−1). The kmax can be considered as an estimation of the biodegradation rate at molecular level, when the available surface area is not limiting biodegradation. An additional hypothesis is that the same polymer tested in soils with different microbial loads would display different kmax. The Michaelis constant (Km), i.e. the surface area at which the reaction rate k is half the maximum rate, is 1122 cm2. It is remarkable to notice that if polybutylene sebacate could be tested in a nanopolymeric form, it could very likely satisfy the Organization for Economic Co-operation and Development (OECD) criteria of “ready biodegradability” for chemicals (e.g. 60% biodegradation in a 10-day window within a 28-day test). This is the first time that the biodegradation kinetics of a solid polymer have been estimated by using the Michaelis-Menten approach.
•This is one of the few systematic studies where the effect of granulometry on biodegradation rate is tackled experimentally.•The surface area and biodegradation rate are well correlated by a double reciprocal model (the Lineweaver-Burk plot).•The maximum biodegradation rate of the polymer when surface area is not a limiting factor was estimated to be very high.•If the polymer were tested in a nanopolymeric form it could satisfy the OECD “ready biodegradability” for chemicals.Ready biodegradable chemicals are expected to undergo biodegradation in any biologically-active environment.
Fused Deposition Modeling (FDM) is an Additive Manufacturing (AM) technique that fabricates parts layer upon layer. The recent development of AM technologies is driving FDM from rapid prototyping to ...rapid manufacturing. However, building end-user functional parts using FDM proved to be a challenging task, which is due to having many processing parameters that may influence the parts’ quality. It is challenging to use full factorial Design of Experiments (DOE) to investigate the influence when there are many processing parameters, especially when the processing parameters are not expected to behave linearly. In addition, to fully exploit the accurate processing parameters influence a large number of sample sets are required. In this paper, Taguchi’s DOE is used to investigate the main effects of four processing parameters in the FDM process, those are the infill percentage, infill pattern, layer thickness, and extrusion temperature. The processing parameters influence is expressed in terms of the mechanical properties and dimensional accuracy of FDM parts fabricated. The material under interest is PLA filament fabricated using a commercial FDM 3D printer. In the presented work, we used Taguchi’s L9 array that had 9 runs with 3 repeated specimens for each, hence a total of 27 specimens were fabricated using varying processing parameters. The dimensions of the fabricated specimens were compared with the 3D CAD model and then tested according to the ASTM D638 standard. The results showed that for generally better dimensional accuracy, a lower extrusion temperature, smaller layer thickness, lower infill percentage, and hexagonal infill pattern were required. In addition, current FDM fabrication process usually generates parts with larger dimensions as compared to the CAD model. On the other hand, to increase the strength of FDM parts, a higher extrusion temperature, an optimized layer thickness, a triangular infill pattern, and a higher infill percentage are required. Ductility can be improved by switching to rectilinear infill pattern and by increasing the layer thickness.
Nanocomposites hold the possible to reform the field of conventional composites together in conditions of recital and prospective applications. Polymer nanocomposites enclose enormous market future ...together as replacements for present composites and in the making of new markets during their great behaviour. It offer advanced technologies and enhances business opportunities to all industrial sectors. This review gives a broad resource for polymer nanocomposite, nanoparticles synthesis, fabrication and testing methods of polymer nanocomposites.
Belt conveyors are currently one of the most commonly used technologies for transporting iron ore. Of the components of the conveyor system, the belt is the most expensive and susceptible to damage. ...Failures due to wear of the rubber cover lead to downtime for corrective maintenance, greater operational risks and performance and economic losses. To improve the tribological performance of conveyor belts, it is necessary to know the main parameters that influence their wear. As wear behavior is not an intrinsic property of a material, the most reliable results are obtained when the wear mechanisms produced in laboratory tests are similar to those in service. In this work, two types were investigated of belt rubber, one new and one worn in service, and four types of iron ore in two class sizes. Loose abrasive wear tests were carried out using the Dry Sand/Rubber Wheel apparatus with belt rubber test pieces and iron ores as abrasives. This work characterized the wear mechanisms that occur in service and in laboratory tests. The predominant wear mechanism found was the formation of Schallamach waves. In the wear tests, Friable Hematite samples presented the highest abrasiveness. In addition, the chemical, mineralogical and morphological features of the iron ore samples were characterized. The high abrasiveness of Friable Hematite was possibly due to the mineral assembly.
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•The main wear mechanism in service and in laboratory was the formation of Schallamach waves.•Positive correlation among distance between waves and abrasive size.•The environmental and operating conditions generated cracks on the worn belt surface.•An adapted methodology to assess the abrasiveness of iron ore in rubber was proposed.•The friable hematite samples had the highest abrasiveness among the analyzed ores.
The main objective of this work is to predict the exact value of the fracture toughness (
) of fiber-reinforced polymer (FRP). The drawback of the American Society for Testing Materials (ASTM) E1922 ...specimen is the lack of intact fibers behind the crack-tip as in the real case, i.e., through-thickness cracked (TTC) specimen. The novelty of this research is to overcome this deficiency by suggesting unprecedented cracked specimens, i.e., matrix cracked (MC) specimens. This MC exists in the matrix (epoxy) without cutting the glass fibers behind the crack-tip in the unidirectional laminated composite. Two different cracked specimen geometries according to ASTM E1922 and ASTM D3039 were tested. 3-D FEA was adopted to predict the damage failure and geometry correction factor of cracked specimens. The results of the TTC ASTM E1922 specimen showed that the crack initiated perpendicular to the fiber direction up to 1 mm. Failure then occurred due to crack propagation parallel to the fiber direction, i.e., notch insensitivity. As expected, the
of the MC ASTM D3039 specimen is higher than that of the TTC ASTM D3039 specimen. The
of the MC specimen with two layers is about 1.3 times that of the MC specimen with one layer.
Acoustic metamaterial attains uncommon material properties over natural material such as negative effective mass density or negative effective bulk modulus or both. The effective bulk modulus of a ...classical acoustic reactive filter such as Helmholtz resonator has been observed negative, using lumped element model, at resonance point, which desires further investigations. Present research demonstrates and establishes robust method to estimate and measure acoustic metamaterial properties of a Helmholtz resonator analytically, numerically and experimentally in detail. The proposed numerical technique simulates ASTM-2611 standard of measurement to extract corresponding reflection and transmission coefficients to evaluate the effective acoustic metamaterial properties. The subsequent investigations have been carried out by taking eight different configurations of Helmholtz resonators such as parallel and series using similar and dissimilar resonators. Performance of each configuration has been investigated analytically, numerically and validated experimentally. At last, a finite array of Helmholtz resonators has been investigated. From investigations, it has been observed that five configurations of Helmholtz resonators and finite array have negative effective mass density and effective bulk modulus. Summarizing, the present research endeavors analytical, numerical and experimental investigations of different configurations of Helmholtz resonators in detail, which is first in its own kind.
Preparation, stability of Nano-fluid and the thermal conductivity of Graphene oxide/Water Nano-fluid with the aim of improving the thermal properties of water were experimentally studied. FESEM and ...XRD tests were used for characterization of nano-particles. After getting assured of the structure of nano-particles, a two-step method was applied to produce Graphene oxide/Water Nano-fluid. Optimal pH, DLS and TEM tests were used to determine the stability. The mass fraction range of the Nano-fluid in this study was 0–1.5%, and the thermal conductivity was measured in the temperature range of 20–60 °C according to ASTM D2717–95 standard. The results indicate that the Nano-fluid has the highest stability at optimum pH (pH = 8). The results of TEM and DLS tests show the sheet structure of the nano-particles and their Nanoscale dimensions in the base fluid, respectively. The thermal conductivity of the Nano-fluid in the study range indicates a significant increase and its maximum increase is 48.1%. Using the curve fitting method, a new correlational with high accuracy has been proposed. Finally, according to the results obtained, it can be said that the Nano-fluid, with respect to its thermal properties in the practical systems, is an appropriate alternative to water-based fluid.
The determination of the efficiency of adhesives applied in glued joints, through the analysis of the percentage of wood failure, is one of the main validation parameters for the quality of gluing ...techniques and adhesive. However, the subjectivity of the interpretation, performance, and visual acuity of the evaluators makes the methodology subjective. This research aimed to establish a method for evaluating the behavior of the glue line in glued joints, using freely available software and digital camera images. Shear samples of glued joints with polyvinyl acetate - PVAc, resorcinol formaldehyde - RF, and melamine formaldehyde - MF were evaluated using digital images obtained by a 16.1-megapixel camera. The images were pre-processed to enable vectorization in Inkscape software, version 1.1.2. Each image was vectorized and subjected to the measurement of the areas of the generated vector layers (glue line and wood). The validation process was performed by evaluating the accuracy of vectorization. Thus, the photograph of each sample and the vectorized image were imported into ImageJ software, version 1.53. To ensure the reliability of the proposed methodology, statistical analyses of the Kappa coefficient, global accuracy, user, and producer were applied. To evaluate the efficiency of the proposed method in relation to the conventional method provided in ASTM D5266-13, five evaluators analyzed the proportion of bond line and wood failure of the 10 samples submitted to the proposed methodology. Subsequently, a descriptive analysis of the data was carried out to evaluate the variability and subjectivity of the conventional analyses among the evaluators. It is noted that the proposed methodology achieved high efficiency in the analysis of the proportion of glue line and wood, and it can be assured by the accuracy tests performed. The research also showed that there was no agreement among the five evaluators using the conventional method. It is concluded that the proposed methodology meets the research objective, with high levels of accuracy, and confirms the subjectivity of the analyses performed with the conventional methodology. The results underscore the need for objective methodologies, employing computational techniques to reduce subjectivity in adhesive bond failure assessments, enhancing critical decisions in the selection of adhesives for industrial structural applications.
•A new methodology for forest planning was proposed.•We consider the main forest genetic materials used in Brazil.•The methodology showed 81% assertiveness.•The proposed methodology had high precision and zero execution cost.•The proposed methodology is feasible and can be adapted to any other area.
Worldwide, improper disposal of plastics is instigating environmental initiatives to combat plastics accumulation of in the environment and the world's oceans. ...Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biocomposites with Miscanthus (Misc) fibres and distillers' dried grains with solubles (DDGS) were studied to ascertain if natural fibres and proteinaceous fillers can improve polyhydroxyalkanoate marine biodegradability. Using ASTM standard D7991-15, the biodegradation of PHBV, PHBV with Misc (15 and 25 wt%) and PHBV with DDGS (15 and 25 wt%) was performed in a simulated marine environment for the first time, as indicated by a literature survey. PHBV/Misc (85/15) and (75/25) biocomposites showed 15 and 25% more biodegradation compared to PHBV, respectively. Proteinaceous PHBV/DDGS (85/15) and (75/25) biocomposites showed 17 and 40% more biodegradation compared to PHBV, respectively. Furthermore, PHBV/Misc (75/25) and PHBV/DDGS (75/25) biocomposites were marine biodegraded in 412 and 295 days, respectively. In conclusion, proteinaceous fillers (DDGS) biocomposites have better marine biodegradability than miscanthus.
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