Weight Fraction Ratio Research Articles

Neural network modeling of thermo-hydraulic attributes and entropy generation of an ecofriendly nanofluid flow inside tubes equipped with novel rotary coaxial double-twisted tape

The current paper numerically predicts the convective heat transfer coefficient, pumping power, and total entropy generation of an ecofriendly-functionalized graphene nanoplatelets nanofluid inside the tubes enhanced with a novel rotary coaxial double-twisted tape, which rotates at various rotational speeds. The impacts of the nanoparticle concentration and twisted ratio are considered. The mathematical models of the heat transfer coefficient, pumping power, and total entropy generation rate are obtained as a function of the weight fraction, angular velocity, and twisted ratio based on the numerical outcomes using Artificial Neural Network (ANN). Several configurations of the neural network are examined, and finally, the best model is found having one hidden layer with 7 neurons in this layer, which can provide excellent precision for measuring the outputs. Moreover, the relevant correlations are presented for all three outputs based on the weights and biases of the ANN.

Properties of Eco-Friendly Concrete Contained Limestone and Ceramic Tiles Waste Exposed To High Temperature

In this recent work, ceramic tiles wastes (CW) were utilized as coarse aggregates in different weight fraction ratios starting with 10% till 100% at an increment of 10% in production of normal concrete. Also, 5% of cement weight was substituted via using limestone powder (LP). Slump value, fresh and dry density, absorption ratio and compressive and splitting tensile strengths were tested at 25 °C. As well, dry density and compressive and splitting tensile strengths were found after exposing the specimens to three target temperatures (200, 400 and 600) °C for 2 h. The results indicated that the usage of CW led to enhancing compressive and splitting tensile strengths at room temperature and the maximum increases in these strengths for 60% of CW, which were 164% and 128%, respectively, compared with normal concrete without CW and LP. The usage of CW enhances behavior of mixes exposed to high temperatures. The maximum remaining compressive strength ratios of tested series exposed to 200 °C and 400 °C were 0.882 and 0.804, respectively, for mixes made by using 50% of CW, and the maximum residual compressive strength ratio for series exposed to 600 °C was 0.780 for mix containing 70% of CW. Maximum remaining splitting tensile strength ratios of three series exposed to (200, 400 and 600) °C were 0.969, 0.895 and 0.836, respectively, for mix containing 70% of CW. The obtained results can give indication of producing environmental concrete with enhanced mechanical properties via using ceramic waste.

Micromechanical and experimental analysis of mechanical properties of graphene/CNT epoxy composites

Amine functionalized multilayer graphene (Af-MLG) and amine functionalized multi wall carbon nano tube (CNT) (Af-MWCNT) were fabricated by sonication method, maintaining the ratio of both the nano fillers as 1:1 and were termed as hybrid fillers due to its composition. The effects of both these fillers on the mechanical properties of epoxy composites were researched upon. Hybrid composite samples were characterized using Scanning electron microscope (SEM) for morphology study. The mechanical behaviour of graphene reinforced epoxy based composites (Gr/Ep-C) were studied using continuum based micromechanical models such as Halpin –Tsai (H-T) and Mori –Tanaka (M−T). The mechanical properties were depicted graphically. The variation in properties have been evaluated with respect to filler weight fraction and aspect ratio using a well defined MATLAB code. The ratio of longitudinal and transverse modulus to the modulus of matrix was then plotted with weight fraction and aspect ratio. When weight fraction and aspect ratio were increased from 0 to 10% and 0–1000 for H-T and M-T models an expected enhancement in the ratio of longitudinal modulus to the modulus of matrix was noticed.

Thermoelastic analysis of rotating multilayer FG-GPLRC truncated conical shells based on a coupled TDQM-NURBS scheme

This work investigates the effect of a thermal shock loading on the rotating multilayer functionally graded graphene platelets reinforced composite (FG-GPLRC) truncated conical shells. The problem is tackled numerically according to the Lord-Shulman (L-S) thermoelastic theory. The multilayer FG-GPLRC conical shells are decomposed into a set of co-axial nanocomposite shell layers, to capture accurately the variation of the thermoelastic field variables due to the layerwise variation of the material properties. The transformed differential quadrature method (TDQM) and a multi-step time integration scheme based on a non-uniform rational B-spline (NURBS) interpolation is applied to discretize the thermoelastic equations together with the related boundary conditions and compatibility conditions at the interface of two neighboring layers. After a preliminary validation of the approach, a parametric study aims at investigating the effect of different graphene platelets (GPLs) distribution patterns, GPLs weight fraction and dimension ratios, as well as the effect of the shell angular velocity and geometry parameters on the thermoelastic response of the system. It is verified that the addition of a small amount of GPLs in the polymer matrix increases significantly the heat wave speed, affects the thermoelastic field variables, and decreases the period of oscillatory portions of the mechanical field variables.

Process design for performance improvement in purely ecofriendly composites for structural applications

ABSTRACTThe chances of improving the properties of biocomposites lie in the efficient combination of processing and compositional parameters. Achieving required properties for a specified application will involve a systematic process design. In this study, we focus on achieving improvement in properties of the bio‐acrylic resin/wood fiber composites via a rational design of process and parameters. We aim to identify processing parameters where the wood fibers participate in the chemical reaction giving rise to a robust composite structure and consequently improved properties. First, processing variables were streamlined to arrive at an efficient, easy, and less expensive processing route. Thereafter, fiber treatment, length, aspect ratio, and weight fraction were correlated to optimize the structural properties. Composites were prepared with varying fiber weight fraction (35–60 wt %) and fiber aspect ratio (2–13.7) using raw wood fibers (RWFs) and raw cellulose fibers (RCFs) from commercial sources. Generally, it was noted that with appropriate choice of treatment and size of fillers, the curing reaction can be enhanced leading to improvement in properties. Results show that flexural strength increases with decrease in fiber aspect ratio for both treated and untreated fibers. Maximum tensile strength (96 MPa) was obtained with 45 wt % filler content and filler aspect ratio of 13.7 for untreated fibers. When compared at the same weight fraction and average fiber length, RCF composites possess about 40% improvement in flexural strength over that of RWFs. The best compromise between processing and properties of the finished ecocomposite varies with fiber aspect ratio, treatment, and weight fraction of the fillers. The study provides an insight for the development of high‐performance green composites for extended applications such as underbody panels, wheel wells, and underhood components. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48719.

Large amplitude free flexural vibrations of functionally graded graphene platelets reinforced porous composite curved beams using finite element based on trigonometric shear deformation theory

In this paper, the large amplitude free flexural vibration characteristics of fairly thick and thin functionally graded graphene platelets reinforced porous curved composite beams are investigated using finite element approach. The formulation includes the influence of shear deformation which is represented through trigonometric function and it accounts for in-plane and rotary inertia effects. The geometric non-linearity introducing von Karman’s assumptions is considered. The non-linear governing equations obtained based on Lagrange’s equations of motion are solved employing the direct iteration technique. The variation of non-linear frequency with amplitudes is brought out considering different parameters such as slenderness ratio of the beam, curved beam included angle, distribution pattern of porosity and graphene platelets, graphene platelet geometry and boundary conditions. The present study reveals the redistribution of vibrating mode shape at certain amplitude of vibration depending on geometric and material parameters of the curved composite beam. Also, the degree of hardening behaviour increases with the weight fraction and aspect ratio of graphene platelet. The rate of change of nonlinear behaviour depends on the level of amplitude of vibration, shallowness and slenderness ratio of the curved beam.

Thermoelastic analysis of FG-GPLRC spherical shells under thermo-mechanical loadings based on Lord-Shulman theory

The transient thermoelastic behavior of functionally graded graphene platelets reinforced composite (FG-GPLRC) spherical shells under thermo-mechanical loadings is studied based on the Lord-Shulman thermoelasticity theory, which includes the coupled as well as the nonlinear terms. The problem formulation is so prepared that both types of commonly used FG-GPLRC in the literature (i.e., multilayer FG-GPLRC, for which the material properties vary in a layerwise or piecewise continuous manner and those with continuously varying material properties) can be analyzed. The modified Halpin-Tsai micromechanical model, rule of mixture and a newly introduced micromechanical model are employed to estimate the effective thermo-mechanical properties of FG-GPLRC shells. The governing equations are discretized in the spatial domain using the layerwise differential quadrature method (LW-DQM). Then, a novel multi-step time integration scheme based on non-uniform rational B-spline (NURBS) in conjunction with Newton-Raphson algorithm are employed to solve the resulting system of nonlinear ordinary differential equations iteratively. In addition, the Laplace transform is employed to obtain the solution in the time domain. The method is validated by performing the convergence study and comparing the obtained results with available solutions in the limit cases. Afterward, the effects of the GPL distribution pattern, GPLs weight fraction and dimensions ratios, the shell thickness-to-outer radius ratio and suddenly applied thermo-mechanical loadings on the thermoelastic behavior of FG-GPLRC spherical shells are investigated. The results show that adding a very small amount of GPLs into polymer matrix significantly increase the shell stiffness and heat wave speed, and considerably changes the temperature and displacement distributions of the FG-GPLRC spherical shells.

Rheological behavior of pH responsive composite hydrogels of chitosan and alginate: Characterization and its use in encapsulation of citral

The pure and composite hydrogels of chitosan with sodium alginate were synthesized at various pH values and characterized by rheology and IR-spectroscopy. Chitosan shows gelation at neutral and basic pH while sodium alginate remains in solution form at all pH values. By careful adjustment of mixing weight fraction ratio and pH, an array of hydrogels with modulated structural dynamics and viscoelasticity, mechanical strength and encapsulation capacity were obtained. At acidic pH, a higher weight fraction of alginate increased the elasticity of the hydrogels while at basic pH more percentage of chitosan stabilized the hydrogel. Strongest composite hydrogels were obtained at acidic pH and gel strength decreased on increasing pH of the synthetic medium. The synthesized hydrogels were studied for their encapsulation capability towards Citral. The pure chitosan hydrogels showed maximum encapsulation capacity followed by the composite hydrogels prepared at neutral pH. This study highlights that a range of composite hydrogels with modified properties can be obtained by simple changes in experimental conditions exploiting physical interactions and can help in better understanding of niche of its applicability in research and industry.

Effect of pressing temperature on the mechanical properties of waste styrofoam filled sawdust composite

This study has investigated the effect of pressing temperature on mechanical properties of waste styrofoam composite filled with sawdust. The waste styrofoam as the matrix was mixed with sawdust as filler and maleic anhydride (6%wt) as a compatibilizer. The weight fraction ratio between matrix and filler 70:30 (wt) and wood fiber size of 100 mesh were conducted. The pressing temperatures were investigated using a hot press with temperatures varied viz. 120, 130, 150, and 170 °C. Surface modification was applied to sawdust to diminish its polarity so that it could be compatible with the non-polar waste styrofoam matrix. Composites were evaluated using Instron and impact tester machine to investigate the tensile strength and impact strength of the material, respectively. The result indicated that tensile strength has decreased with the increase of pressing temperature where the largest tensile strength is at 130 °C of 33 MPa. The same trend has occurred on impact strength, where the value has reached of 300 J/cm2 on pressing temperature of 130 °C. From scanning electron microscopy (SEM) analysis it is also confirmed that during impact test, the resistance of the composite which has been pressed at the temperature of 130 °C have given better morphology than the composite at 170 °C.

The Effect of Additive Particulate on same Physical and Electrical Properties of Polymeric Composites

This work includes adding Aluminum particles (Al) , Nickel particles (Ni) and mixture of (Al +Ni) particles of grain size (40 m) to Epoxy resin with weight fractions ratio (2%, 4%, 6%, 8%). Tests which were studied dielectric constant and thermal conductivity . Experimental results showed that, the values of dielectric constant increases with increasing the weight fraction ratio of additive particles before and after (UV) irradiation.Thermal conductivity increases slowly with increasing weight fraction ratio of additive particles before and after (UV) irradiation. The maximum value of thermal conductivity was for samples reinforced with for (Al) particle followed by samples reinforced with (Ni) and particle mixture of (Al+Ni) particles.

Disparity in hydrophobic to hydrophilic nature of polymer blend modified by K 2 Ti 6 O 13 as a function of air plasma treatment

Abstract Polymer blends of Poly (vinylidenefluoride) (PVDF)/Poly (methyl methacrylate) (PMMA) were modified by Potassium hexa-titanate oxide (K 2 Ti 6 O 13 ) in weight fraction ratio. The blends were further exposed to air plasma treatment. The alteration of surface morphology due to plasma treatment was analyzed using polarizing optical, scanning electron and atomic force microscopic techniques. The confirmation of chemical composition and elemental analysis of untreated and treated blends were done using Fourier transform infrared spectrum (FTIR) and energy dispersion spectroscopy (EDS). Theoretical methods of calculating contact angle (θ°), surface energy (γ SE ), and roughness average (R a ) were disclosed to evaluate the experimental data. The microscopic observations clearly demonstrated the synergic effect induced by plasma treatment which improved the surface energy and formation of micro texture. Surface energy was estimated from contact angle data, which demonstrate the significant disparity in hydrophobic to hydrophilic nature. It is well known that the air plasma treatment incorporates polar functional groups onto the surface, which is responsible for the decrease in contact angle. Further, the increase in surface roughness as seen from AFM is also responsible for the decrease in contact angle and hydrophilic nature. The optimization of barrier properties of polymer blends using plasma treatment can be useful in the development of liquid attracting layer applications.

Modeling of elastic behavior of carbon nanotube-reinforced polymers by accounting the interfacial debonding

In this study, a three-phase multiscale model is developed to study the elastic behavior of the carbon nanotube-reinforced polymer composites. The cohesive zone model is implemented to model the carbon nanotubes debonding. The effects of weight fraction and aspect ratio of the carbon nanotubes as well as the strength of the interfacial adhesion on the effective elastic response of the nanocomposite have been investigated. A good agreement is obtained between the predicted and available experimental results when the cohesive interface is introduced in the model. The results show that carbon nanotube/polymer interfacial strength has more significant effect on the nanocomposites modulus and stiffness for higher values of weight fraction and aspect ratio.

Morphology, thermal, and electrical properties of polypropylene hybrid composites co‐filled with multi‐walled carbon nanotubes and graphene nanoplatelets

ABSTRACTIn this study, nanocomposites of polypropylene (PP) with various loadings of multi‐wall carbon nanotubes (MWCNT) and graphene nanoplatelets (GnP) were formed by masterbatch dilution/mixing approach from individual masterbatches PP‐MWCNT and PP‐GnP. Melt mixing on a twin‐screw extruder at two different processing temperatures was followed by characterization of morphology by transmitted‐light microscopy including the statistical analysis of agglomeration behavior. The influence of processing temperature and weight fractions of both nanofillers on the dispersion quality is reported. Thermal properties of the nanocomposites investigated by DSC and TGA show sensitivity to the nanofillers weight fraction ratio and to processing conditions. Electrical conductivity is observed to increase up to an order of magnitude with the concentration of each nanofiller increasing from 0.5 wt % to 1.0 wt %. This is related with a decrease of electrical conductivity observed for unequal concentration of both nanofillers. This particular behavior shows the increase of electrical properties for higher MWCNT loadings and the increase of thermo‐mechanical properties for higher GnP loadings. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42793.

Effect of organoclay on morphology and electrical conductivity of PC/PVDF/CNT blend composites

In this work, different contents of the organoclay (0.05–0.25 wt%) were introduced into the polycarbonate/poly(vinylidene fluoride)/carbon nanotube (PC/PVDF/CNT) blend composites by diluting the master batches of the PC/organoclay and the PVDF/CNT through melt-compounding in an internal mixer. In the blend composites, the weight fraction ratio between PC and PVDF was maintained at 40/60, and the content of the CNTs was varied from 0.1 to 0.5 wt%. The morphologies of the blend composites and the dispersion states of the nanofillers were characterized using scanning electron microscope and transmission electron microscope. Differential scanning calorimetry was used to investigate the crystallization behaviors of different blend composites so that the selective localization of the CNTs could be proved further. The results showed that with the presence of the CNTs and/or the organoclay, the blend composites showed the apparent morphological change from a typical sea-island structure to the quasi-cocontinuous structure. Specifically, at the organoclay content of 0.1 wt%, most of the CNTs selectively located at the blend interface. The electrical resistivity was measured and the results showed that organoclay showed apparent influence on the electrical resistivity of the blend composites. Namely, the volume resistivity decreased with increasing organoclay content until a minimum value was achieved, then it increased gradually with further increasing organoclay content. Specifically, all the blend composites exhibited the minimum electrical resistivity at the 0.1 wt% organoclay. Furthermore, a very small percolation threshold of the CNTs (0.06 wt%) was achieved in this work, which was attributed to the selective localization of the CNTs at the blend interface.

Investigation on Mechanical Property Evaluation of Jute - Glass Fiber Reinforced Polyester

Natural fibers have been investigated for use in polymers including flax, hemp, jute, sisal and banana. Recently there has been a greater leaning towards natural fiber reinforced polymers composites because these are environmental friendly and cost effective to synthetic fiber reinforced composites. In this work hand lay-up process is used to fabricate Jute- glass fiber reinforced polyester composites. Specimen preparation and testing was carried out as per ASTM standards. Composites were prepared using Jute - glass fibers of 50/50, 40/60 and 30/70 Weight fraction ratios and mechanical properties like tensile, impact and flexural strength of Jute - glass fiber reinforced polyester were evaluated. The results shows that tensile strength and impact Strength of 50% Jute-50% glass fiber composition is found to be better than the other two compositions and the flexural strength of 40% Jute-60% glass fiber composition is found to be better than the remaining two compositions. Keywords: Jute, glass fiber, Polyester, Hand Lay-up, Mechanical properties.

Bayes Statistical Analyses for Particle Sieving Studies

Particle size is commonly used to determine quality and predict performance of particle systems. We consider particle size distributions inferred from a material sample using a fixed number of sieves with progressively smaller size openings, where the weight of the particles in each size interval is measured. In this article, we propose Bayes analyses for data from particle sieving studies based on parsimoniously parameterized multivariate normal approximate models for vectors of log weight fraction ratios. Additionally, we observe that the basic approach extends directly to modeling mixture contexts, which provides model flexibility and is a very natural extension when physical mixtures of materials with fundamentally different particle sizes are encountered. We also consider hierarchical modeling, where a single process produces lots of particles and the data available are (replicated) weight fraction vectors from different lots. Supplementary materials for this article are available online.

Use of bagasse fiber ash as secondary filler in silica or carbon black filled natural rubber compound

This work studies possibilities of using bagasse fiber ash (BFA) as alternative and/or secondary filler in natural rubber (NR) compounds containing either precipitated silica (PSi) or carbon black (CB) as the primary filler. The effects of the filler content and weight fraction ratio of BFA in PSi and CB fillers on cure characteristics, and mechanical properties were of interest. The studies reveal that silicon dioxide (SiO2) was the major component of BFA with 75.4% by weight and the rest was metal oxides. The BFA particles showed porosities and shape irregularities with a particle size range of 45–150μm. For the neat filler system, it was found that the BFA filler could be used potentially as alternative filler in NR compounds with a recommended loading of not greater than 15 parts per hundred rubber. Lower tensile strength of the vulcanizate with BFA filler, as compared to PSi and CB filler, was due to the poor dispersion level and an aggregation of the silica particles in the rubber matrix. In the hybrid filler system, BFA could be used to replace both PSi or CB filler up to 75% of the total hybrid filler (either BFA:PSi or BFA:CB) not exceeding 15phr, without affecting the ultimate mechanical properties. The results of ultimate mechanical strength and swelling measurements clearly indicated that the BFA filler had more compatibility for addition with PSi filler than CB.

Thermal characteristics of oleochemical carbonate binary mixtures for potential latent heat storage

AbstractThe thermal properties for binary mixtures at various weight fraction ratios between dodecyl carbonate (1a), tetradecyl carbonate (1b), hexadecyl carbonate (1c), and octadecyl carbonate (1d) were examined by DSC at 0.5, 1.0, and 5.0°C/min. At 5°C/min sharp well defined phase transitions were observed at 80:20, 88:12, and 90:10, for 1a:(1b, 1c, and 1d), respectively, at 74:26 and 80:20 for 1b:(1c, and 1d), respectively, and at 82.5:17 for 1c:1d. The melting and solidification temperatures for these mixtures ranged between 12–37°C (melting) and 8–34°C (solidification). The latent heat of melting and solidification determined for the binary carbonate mixtures ranged between 135 and 175 J/g. At 0.5 or 1.0°C/min, mixtures of 1a:(1b, 1c, and 1d) and 1b:1d melted and solidified similarly when run at 5°C/min while the melting curves for 1b:1c and 1c:1d were not as well defined. These carbonate mixtures extend the thermal properties of the pure oleochemical carbonates and compliment other biobased phase change materials (PCMs) substances such as fatty acids, esters, and alcohols and may provide useful biobased alternatives to paraffin wax and salt hydrate PCM currently dominating the market.

Morphology Diagram of a Diblock Copolymer−Aluminosilicate Nanoparticle System

We explore the morphology space of nanocomposites prepared from poly(isoprene-block-ethylene oxide) (PI-b-PEO) diblock copolymers as structure directing agents for aluminosilicate nanoparticles prepared from (3-glycidyloxypropyl)trimethoxysilane (GLYMO) and aluminum(III) sec-butoxide. The results of structural investigations of over 60 polymer−inorganic nanocomposites are reported. They are obtained from 12 different block copolymers of varying molecular weight (∼10−100 kg/mol) and PEO weight fraction (fw ∼ 0.1−0.8) through addition of different amounts of inorganic components. Eight different morphologies as well as composites with biphasic character are observed. Individual block copolymers show up to five different well-defined morphologies upon addition of the inorganic sols. Differential scanning calorimetry (DSC) studies on the composites show that the addition of the inorganic components suppresses PEO crystallization when the inorganic to PEO weight fraction ratio of the composites is greater than 1.3−1.5. The eight phases are mapped out using two- and three-component morphology diagrams.

Determination of tensile, flexural properties and microstructural characterization of calcium carbonate filler reinforced polypropylene matrix composites

Calcium carbonate is one of the commonly used inorganic filler reinforcements in polypropylene matrix. In this research work, granules of chicken egg shell containing natural organic calcium carbonate resource has been introduced to reinforce in the polypropylene base material. The aim of this experimental study is to determine the tensile, flexural properties and to characterize the microstructures of granular chicken shell containing natural calcium carbonate reinforced in polypropylene. Chicken egg shells are crushed and sieved and granules of size 160μm are selected for reinforcement in the polypropylene matrix. The granules are then mixed with polypropylene base material with silane as a coupling agent proportionally in order to obtain four different proportions 10%, 20%, 30% and 40% on weight fraction basis with the aid of an extrusion machine. Experimental result have shown improvements in Tensile Modulus and Flexural Modulus of this newly processed natural organic calcium carbonate filler reinforced polypropylene composites, although it has not improved the tensile strength, flexural Strength and strain to fracture. The weight fraction ratio of the filler reinforced in the matrix which gave the highest tensile and flexural modulus is 20% and 10%, respectively.