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Tensile, Thermal and Morphological Characterization of Cocoa Bean Shells (CBS)/Polycaprolactone-Based Composites
Get PDFIn this work, cocoa bean shells (CBS), which were ground, then sieved to less than 150 μm and dried in a vacuum oven, have been introduced in a polycaprolactone (PCL) matrix in three different amounts, 10, 20 and 30% wt. The obtained composites were tested under tensile loading, which indicated an enhanced rigidity with a slight decrease of strength with respect to the neat polymer and a reduced elongation, particularly evident for composites with 30 wt% CBS, where final collapse took place for strains only slightly exceeding the yielding point. Differential scanning calorimetry (DSC) indicated a rather negligible variation of melting temperature with respect to pure PCL, whilst thermogravimetric analysis (TGA) for CBS showed evident peaks for degradation of hemicellulose, pectin, then most clearly for cellulose at 313 °C and a final residue of 33.3% at 900 °C. Scanning electron microscopy images taken on the 30% wt. composite offered evidence of brittle fracture with appearance of irregular structures, related to the pull-out and fibrillation of cocoa shells
Physicochemical and Mechanical Properties of Gelatin Reinforced with Nanocellulose and Montmorillonite
Get PDFOrganic rodlike cellulose nanocrystals extracted from sisal fibers and inorganic montmorillonite based on silicate layers were employed to develop bionanocomposites based on gelatin matrix. Bionanocomposites with cellulose nanocrystal, montmorillonite and both nanoreinforcements combined were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis and differential scanning calorimetry. Tensile properties and oxygen and water vapor gas permeability values were determined to study the influence of the addition of nanoreinforcements, different in nature, to gelatin matrix. Bionanocomposites with montmorillonite improved tensile strength but systems reinforced with nanocellulose showed lower tensile strength than neat gelatin ones. Oxygen gas permeability values decreased for all bionanocomposites, especially for montmorillonite systems; however, after the incorporation of reinforcements water vapor permeability increased
Cellulose Nanomaterials as Binders: Laminate and Particulate Systems
Get PDFA novel application of cellulose nanomaterials, particularly cellulose nanofibrils (CNF) as a binder in conventional and novel laminate and particulate composite systems is discussed. Using cellulose nanomaterials as a reinforcing agent in conventional polymer composites faces several difficulties: 1) there are no easy ways to dry the CNF and maintain nanoscale dimensions, 2) there are compatibility issues related to cellulose-polymer bonding, and 3) there are issues related to obtaining a good distribution and redispersion of nanoscale materials inside a polymer matrix. An alternative strategy is applications in which cellulose nanomaterials can be used in the aqueous suspension form without first needing to dry them. In addition, applications should be targeted that take advantage of the impressive strength properties of these nanomaterials while capturing the nanoscale material property enhancements in the final product. It has been demonstrated that CNF is able to bond lamina of paper together to produce a new class of all-renewable paper nanolaminates with exceptional mechanical properties exceeding many reinforced plastic formulations. It has also been demonstrated that particleboard panels can be successfully manufactured without any added formaldehyde by complete replacement of urea-formaldehyde resin. Efforts to use cellulose nanomaterials in paper applications are also reviewed as well as adhesion mechanisms involved in such composite systems. The future outlook and potential market opportunities concerning this new application of cellulose nanomaterials, as well as known and potential limitations and challenges in the way of commercialization efforts, are presented
Wave Propagation in a Magneto-Micropolar Thermoelastic Medium with Two Temperatures for Three-Phase-Lag Model
Get PDFThe present paper is concerned with the wave propagation in a micropolar thermoelastic solid with distinct two temperatures under the effect of the magnetic field in the presence of the gravity field and an internal heat source. The formulation of the problem is applied in the context of the three-phase-lag model and Green-Naghdi theory without dissipation. The medium is a homogeneous isotropic thermoelastic in the half-space. The exact expressions of the considered variables are obtained by using normal mode analysis. Comparisons are made with the results in the two theories in the absence and presence of the magnetic field as well as the two-temperature parameter. A comparison is also made in the two theories for different values of an internal heat source
Numerical Investigation Of Flow Dynamic In Mini- Channel: Case Of A Mini Diode Tesla
Get PDFMicrofluidic systems are used and exploited in various fields, as they are highly specific and developed in their use. The micro devices are used in various analyzes of medical disciplines, chemical and other fields. Our research team "MAAt" within ENERGARID laboratory is in the process of triggered several lines of research in this area, the micro-mixing, separation of micro particles, droplet production. For that, we need tools and micro devices to study the phenomena.. In this work, we present a theoretical study and numerical simulation of micro device (micro diode Tesla). A Diode Tesla is similar to a heart valve conduit profile is shown in the following figure: In this simulation work, we will focuse the variation of geometrical parameters, the inside length lw (lw1> lw2> lw3), this study aims to optimize this setting to get a better efficiency. Then we will investigate the effect of the pressure variation on the volume flow
Research on the Damage of Porosityand Permeabilitydue to Perforation on Sandstone in the Compaction Zone
Get PDFA perforating hole is a channel through which the oil and gas in a reservoir pass into the production well bore. During the process of perforating due to explosion, the surrounding sandstone will be damaged to a certain extent, which will increase the well bore skin and lead to the decrease of production consequently. In this work a mechanical model of perforating damage is developed to describe the influences of perforating due to explosion on the porosity and permeability of the surrounding sandstone near the compaction zone. Based on this developed model, the important data related to the damage of sandstone, such as matrix effective stress, plastic deformation, volumetric strain, and so on, can be numerically simulated. Especially the behaviors of plasticity kinematic hardening at high strain rate due to impact loads, which are the important characteristics in the sandstone, is taken into account in this developed model. Both numerical and testing results show that the damage due to perforation in the sandstone can be accurately predicted by the developed model together with the porosity and permeability evolving model of perforation in a compaction zone. As a practical application, a methodology for the analysis of damage of porosity and permeability around a perforation tunnel is supposed based on the developed model and the core flow efficiency test of interparticle pore spaced sandstone target in China Shengli Oilfield and the computed tomography test
Excluded Volumes of Anisotropic Convex Particles in Heterogeneous Media: Theoretical and Numerical Studies
Get PDFUnderstanding the excluded volume of anisotropic particle is of great importance in the evaluation of continuum percolation and random packing behaviors of soft/hard particle systems in heterogeneous disordered media. In this work, we obtain the excluded volumes of several anisotropic convex particles including prolate spheroids, oblate spheroids, spherocylinders, and Platonic particles, using theoretical and numerical approaches. According to the second virial coefficient, we first present a theoretical scheme for determining the excluded volumes of anisotropic particles. Also, the mean tangent diameters of anisotropic convex particles are formulated by the quantitative stereology. Subsequently, Monte Carlo simulations are demonstrated to numerically evaluate the excluded volumes. The theoretical results of the dimensionless excluded volume are thereafter compared with that of the numerical results to verify the validity of the theoretical scheme. We further investigate the dependence of the dimensionless excluded volume on the geometric characteristics of anisotropic particles based on the proposed theoretical and numerical schemes. Results show that the dimensionless excluded volume mainly relies on the shape and surface information of anisotropic particles. The developed theoretical and numerical schemes can provide theoretical insights into the percolation threshold and packing density of soft/hard anisotropic particle systems in heterogeneous materials, physics, and chemistry fields
Effects of Stacking Sequence and Impactor Diameter on Impact Damage of Glass Fiber Reinforced Aluminum Alloy Laminate
Get PDFThe methods of numerical simulation and test are combined to analyze the impact behavior of glass fiber reinforced aluminum alloy laminate (GLARE). A new failure criteria is proposed to obtain the impact failure of GLARE, and combined with material progressive damage method by writing code of LS-DYNA. Low velocity impact test of GLARE is employed to validate the feasibility of the finite element model established. The simulation results have been shown that progressive damage finite element model established is reliable. Through the application of the finite element model established, the delamination of GLARE evolution progress is simulated, various failure modes of GLARE during impact are obtained, and the effects of stacking sequence and impactor diameter on the impact damage of GLARE are obtained
Experimental study of interfacial phenomena between the heavy oil and maximum solvent concentration as function of injection pressures
Get PDFHeavy Oil is an up and coming energy resource that is aggressively being sought after as the world’s energy demand increases. As technology continues to improve, this once costly energy source is quickly becoming a more viable alternative. Vapor extraction (Vapex) process is an emerging technology for viscous oil recovery that has gained much attention in the oil industry. The vapor extraction of heavy oil system is presented to describe experimental setups and procedures used to perform different experiments of vape extraction process. The generated experimental data were used to calculate the live oil maximum interfacial solvent concentration as function of injection pressures. In this work the effect of solvent injection pressure pulsing on oil production rates and recovery was investigated. The lab-scale experiments were designed and carried out to investigate this concept. The experiments were performed injecting pure butane at injection pressures of 91.01, 97.90, 104.80, and 111.69 kPa and 21 ̊C for about 6 to 7 hours. A cylindrical physical model with 25 cm heights was packed with permeability 204 Darcy and saturated with heavy oil at high viscosity. The experiments were performed with different policies of solvent injection pressure versus time. Pressure pulsing was introduced by sudden release and re-injection of the solvent gas. Compared to constant injection pressure the pressure pulsing further enhanced the oil production rates and recoveries in Vapex process
B-Spline Wavelet on Interval Finite Element Method for Static and Vibration Analysis of Stiffened Flexible Thin Plate
Get PDFA new wavelet finite element method (WFEM) is constructed in this paper and two elements for bending and free vibration problems of a stiffened plate are analyzed. By means of generalized potential energy function and virtual work principle, the formulations of the bending and free vibration problems of the stiffened plate are derived separately. Then, the scaling functions of the B-spline wavelet on the interval (BSWI) are introduced to discrete the solving field variables instead of conventional polynomial interpolation. Finally, the corresponding two problems can be resolved following the traditional finite element frame. There are some advantages of the constructed elements in structural analysis. Due to the excellent features of the wavelet, such as multi-scale and localization characteristics, and the excellent numerical approximation property of the BSWI, the precise and efficient analysis can be achieved. Besides, transformation matrix is used to translate the meaningless wavelet coefficients into physical space, thus the resolving process is simplified. In order to verify the superiority of the constructed method in stiffened plate analysis, several numerical examples are given in the end