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Cellulose Acetate/Carbon Nanotube Composites by Melt Mixing
Get PDFCellulose acetate (CA) is produced from a natural polymer and presents excellent properties, finding applications in a variety of areas. Unlike cellulose, CA is melt processable and may be molded into parts and formed into fibers or films. In this context, the production of conductive CA composites that may be processable and integrated into parts to provide specific functionalities is an area of increasing interest. The present work aims to prepare electrically conductive composites based on CA and carbon nanotubes (CNTs) by melt mixing. The nanocomposites were produced with pure and pyrrolidine-functionalized nanotubes, using a batch mixer and a twin-screw extruder. The morphology of carbon nanotube dispersion, the rheological behavior and the electrical conductivity of the final composites were evaluated. Rheological percolation was achieved for the composites with 0.5 wt% of CNT—both pure and functionalized—produced by extrusion; while electrical percolation was observed only for the composites with pure CNT
Synthesis and Application of a Novel Epoxidized Plasticizer Based on Cardanol for Poly(vinyl chloride)
Get PDFCardanol, an agricultural by-product of the industrial processing of cashew, was used to synthesize epoxidized cardanol laurate (ECDL) plasticizer. The target product was characterized using FTIR, 1H NMR and 13C NMR. The plasticizing effect of ECDL substitution for petroleum-based plasticizer dioctyl phthalate (DOP) in soft poly(vinyl chloride) (PVC) was investigated using dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and mechanical testing, and compared to PVC incorporated with commercial epoxidized soybean oil (ESBO). When DOP was partially substituted by EDCL, there was a slight increase of 5% in glass transition temperature (Tg) and a maximum increase of 14.55% in the elongation at break. In addition, scanning electron microscopy (SEM) revealed that the morphology of blends plasticized with DOP incorporated with ECDL was finer and more homogeneous compared with blends plasticized with neat DOP or ESBO. Compared with DOP/PVC, TGA results showed that the initial degradation temperature (Ti), the 50% weight loss temperature (T50), and the first peak decomposition temperature (Tp1) for ECDL/PVC increased by 16.8, 26.5 and 7.1 °C, respectively. Moreover, plasticizing system with ECDL had longer stability time, lower volatility and exudation loss, and higher chemical resistance than that of DOP. Therefore, as an environmentally friendly and renewable biobased plasticizer, ECDL can partially replace DOP
Particleboard Based on Rice Husk: Effect of Binder Content and Processing Conditions
Get PDFIn the development of materials based on renewable resources, the search for lignocellulosic substitutes for wood is one of the biggest challenges that academia and the particleboard and wood industries are facing. In this article, particleboards were processed using rice husk, an agricultural waste, as a substitute for wood. Rice husk without any further treatment was processed into particleboards using phenol-formaldehyde resin as binder. The effect of the processing parameters, pressure and binder content (BC) on the density, water absorption (WA), thickness swelling (TS), modulus of rupture (MOR) and modulus of elasticity (MOE) was analyzed. The performance of the obtained panels was evaluated in comparison with the US Standard ANSI/ A208.1. Particleboards with 11% of BC met the minimum requirements of MOR and MOE recommended by the ANSI specifications for commercial use, while particleboards with high BC (14%) also accomplished the requirements for industrial use, finding a resourceful use for this agricultural waste
Numerical Shock Viscosity for Impact Analysis Using ALE Formulation
No full textWhen the simulation takes account of dissipative mechanisms, e.g. heat conduction and viscosity, the shocks become smeared out to produce thin layers of rapidly and continuously varying energy, density, pressure and velocity rather than discrete surfaces of mathematical discontinuity. In the mid twentieth century, Von Neumann and Richtmyer suggested the use of a viscous pressure term (bulk viscosity) in the equilibrium equations for ideal gases in order to examine the shock while avoiding numerical oscillations at the shock front. When the bulk viscosity is included in the conservation equations, the comprehensive physics present a continuous solution satisfying the Rankine-Hugoniot conditions. Nevertheless, the published literature includes few engineering and research studies presenting the novel equilibrium equations in which the incorporation of bulk viscosity generates a continuous solution in keeping with conservation laws. The present work is aimed at demonstrating that the artificial bulk viscosity defined by Von Neumann and Richtmyer is also applicable to fluids described by a density-linear equation of state, that the novel equations present a continuous solution, and that a shock layer of the same order as the computational grid is generated. Although the method has been employed and mathematically proven for one-dimensional flow, it would seem to be just as relevant to the analysis of more complex flow dynamics and fluid structure interactions via an application of the Arbitrary Lagrangian Eulerian (ALE) formulation
Plane Vibrations in a Transversely Isotropic Infinite Hollow Cylinder Under Effect of the Rotation and Magnetic Field
Get PDFThe aim of this paper is to study the effects of rotation and magnetic field on the plane vibrations in a transversely isotropic material of an infinite hollow cylinder. The natural frequency of the plane vibrations in the case of harmonic vibrations has been obtained. The natural frequencies are calculated numerically and the effects of rotation and magnetic field are discussed. The numerical results obtained have been illustrated graphically to understand the behavior of frequency equation with different values of frequency under effects the rotation and magnetic field. Comparison was made with the results obtained in the presence and absence of the rotation and magnetic field. The results indicate that the effect of rotation and magnetic field are very pronounced
A Comparative Study of Bayes Classifiers for Blade Fault Diagnosis in Wind Turbines through Vibration Signals
Get PDFRenewable energy sources are considered much in energy fields because of the contemporary energy calamities. Among the important alternatives being considered, wind energy is a durable competitor because of its dependability due to the development of the innovations, comparative cost effectiveness and great framework. To yield wind energy more proficiently, the structure of wind turbines has turned out to be substantially bigger, creating conservation and renovation works troublesome. Due to various ecological conditions, wind turbine blades are subjected to vibration and it leads to failure. If the failure is not diagnosed early, it will lead to catastrophic damage to the framework. In order to increase safety observations, to reduce down time, to bring down the recurrence of unexpected breakdowns and related enormous maintenance, logistic expenditures and to contribute steady power generation, the wind turbine blade must be monitored now and then to assure that they are in good condition. In this paper, a three bladed wind turbine was preferred and using vibration source, the condition of a wind turbine blade is examined. The faults like blade crack, erosion, hub-blade loose connection, pitch angle twist and blade bend faults were considered and these faults are classified using Bayes Net (BN), Discriminative Multinomial Naïve Bayes (DMNB), Naïve Bayes (NB), Simple Naïve Bayes (SNB), and Updateable Naïve Bayes (UNB) classifiers. These classifiers are compared and better classifier is suggested for condition monitoring of wind turbine blades
New Closed- and Open-Cell, Aldehyde-Free Protein Foams
Get PDFNew aldehyde-free and isocyanate-free biofoams have been obtained by reacting albumin chicken egg white and dimethyl carbonate (DMC). The optimized formulations yielded lightweight foams whose densities were evaluated as 0.016–0.16 g/cm3. Mechanical resistance was 0.023–0.34 MPa and residual pH nearly neutral. The new foams presented up to 57% of closed cells as measured by helium pycnometry and good thermal insulation. These new natural foams are environmentally friendly materials and show very promising properties
A Novel Plant-Based Biosorbent for Removal of Copper (II) from Aqueous Solutions: Biosorption of Copper (II) by Dried Plant Biomass
Get PDFBiosorption effectively removes heavy metal ions by using inexpensive biosorbents. In this study, Portulaca oleracea plant waste biomass was used as environmentally friendly biosorbent for the removal of copper ions from aqueous solution. This article includes the study of the effects of various important parameters on the biosorption process. Maximum biosorption was found to occur under slightly acidic conditions (pH 6). Small particle size, moderate agitation speed, and moderate temperature favor the biosorption process. The Langmuir model was most suitable, showing the biosorption capacity to be 85.470 mg/g. Pseudo-secondorder model best described the kinetics of the biosorption process. Thermodynamic studies suggested the spontaneous and endothermic nature of biosorption. The results from the present study suggest that copper can be successfully removed from aqueous solution by waste portulaca plant biomass. This new biosorbent has proven to be an efficient, low-cost, environmentally friendly material
Graphene-Based 3D Xerogel as Adsorbent for Removal of Heavy Metal Ions from Industrial Wastewater
Get PDFGraphene-based 3D porous xerogel was designed through molecular self-assembly of graphene oxide on chitosan matrix and its application in removal of different heavy metal ions from wastewater was investigated. The synthesized xerogel was characterized through FTIR, SEM, XRD and BET surface area analysis. Heavy metal ions, including Pb(II), Cd(II), and Hg(II), were removed from wastewater using this graphene-chitosan (GO-Cs) xerogel and the removal efficiency was monitored through inductively coupled plasma mass spectrometry (ICP-MS). The effect of GO-Cs composition and pH on adsorption efficiency as well as the kinetics of adsorption was studied in detail. The study exhibited that this xerogel is more suited for the removal of Pb(II) than Cd(II) and Hg(II). It was demonstrated that the large surface area and highly porous structure of this nanomaterial make it a suitable candidate for the remediation of industrial wastewater pollutants