CFD simulation of gas–solid bubbling fluidized bed: A new method for adjusting drag law

In computational fluid dynamics modelling of gas–solid two phase flow, drag force is one of the dominant mechanisms for interphase momentum transfer. Despite the profusion of drag models, none of the available drag functions gives accurate results in their own original form. In this work the drag correlations of Syamlal and O'Brien (Syamlal and O'Brien, Int. J. Multiphase Flow. 1988; 14(4):473–481), Gidaspow (Gidaspow, Appl. Mech. Rev. 1986; 39:1–23), Wen and Yu (Wen and Yu, Chem. Eng. Prog. Symp. Ser. 1966; 62(2):100–111), Arastoopour et al. (Arastoopour et al., Powder Technol. 1990; 62(2): 163–170), Gibilaro et al. (Gibilaro et al., Chem. Eng. Sci. 1985; 40:1817–1823), Di Felice (Di Felice, Int. J. Multiphase Flow. 1994; 20(1):153–159), Zhang‐Reese (Zhang and Reese, Chem. Eng. Sci. 2003; 58(8):1641–1644) and Hill et al. (Hill et al., J. Fluid Mech. 2001; 448:243–278) are reviewed using a multi‐fluid model of FLUENT V6.3.26 (FLUENT, 2007. Fluent 6.3 User's Guide, 23.5 Eulerian Model, Fluent, Inc.) software with the resulting hydrodynamics parameters being compared with experimental data. The main contribution of this work is to propose an easy to implement and efficient method for adjustment of Di Felice drag law which is more efficient compared to the one proposed by Syamlal‐O'Brien. The new method adopted in this work showed a quantitative improvement compared to the adjusted drag model of Syamlal‐O'Brien. Prediction of bed expansion and pressure drop showed excellent agreement with results of experiments conducted in a Plexiglas fluidized bed. A mesh size sensitivity analysis with varied interval spacing showed that mesh interval spacing with 18 times the particle diameter and using higher order discretization methods produces acceptable results.     

Improvement of bond strength of BPDA‐PDA‐type polyimide film by corona discharge treatment

Aromatic polyimide film composed of biphenyl tetracarboxylic acid dianhydride (BPDA) and p‐phenylene diamine (PDA) is a very stable polymer at high temperatures and very useful for the electronics industry. Bonding properties were improved by corona discharge treatment of this film. The chemical modification method was applied for generated functional groups, that is, carboxylic, hydroxyl, and amino groups in the gas phase, and the quantity of these functional groups was determined by X‐ray photoelectron spectroscopy. The functional groups increased with corona energy, leveling off at a specific corona energy. The bond strength of the copper foil/adhesive/polyimide film was determined. The relationship between bond strength and functional group content was analyzed by multivariate analysis. Bond strength could be sufficiently correlated with functional group quantity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3403–3408, 2006     

Electric currents generated by turbulent flows of liquid hydrocarbons in smooth pipes: Experiment vs. theory

Available data on the electric convection current generated by turbulent liquid hydrocarbon flows in smooth-walled pipes are reviewed and compared with the theory of Abedian and Sonin (1982, J. Fluid Mech.120 199–217). A good comparison is obtained by assuming a single value of the zeta-potential for all experiments.     

Discussion on second-order dispersed phase Eulerian equations applied to turbulent particle-laden jet flows

In this work a Reynolds stress two-phase flow model is presented. Equations for the second-order statistical moments are considered for both phases, continuous and dispersed, in the limit of high-inertia non-colliding particles. A simplified version of this model is used for studying axisymmetric particle-laden gas jets. Emphasis is made in the analysis of the dispersed phase equations only. The equations for radial and axial momentum and normal Reynolds stresses for the particulate phase are divided into their basic terms and analysed separately. The modelling of the corresponding shear stresses relies on a Boussinesq closure, consistent with the theoretical work of Reeks (Phys. Fluids A 5(3) (1993) 750) and Zaichik (J. Appl. Math. Mech. 61 (1997) 127) in the limit of high-inertia particles. By this procedure a global picture of the momentum and fluctuating energy transfer in the flow is attained. Moreover, the dispersed phase and fluid-particle velocity correlation, that enter the interaction terms describing the exchange of fluctuating energy between the phases, are compared with the result of Reeks’ and Zaichik's theoretical expressions in the case of simple shear flow.     

Viscometric studies of poly(N‐vinyl‐2‐pyrrolidone) in water and in water and 0.01% bovine serum albumin at 283.15, 288.15, 293.15, 298.15, 303.15, 308.15, and 313.15 K

Viscosity and density studies for 0.01–0.14% (w/w) poly(N‐vinyl‐2‐pyrrolidone) (PVP) in water and in water and 0.01% bovine serum albumin (BSA) were conducted at 283.15, 288.15, 293.15, 298.15, 303.15, 308.15, and 313.15 K. The viscosity coefficients and the activation‐energy, free‐energy, enthalpy, and entropy changes were calculated from viscosity data for viscous flow. On this basis, PVP–PVP, PVP–BSA, PVP–water, and BSA–water interactions and PVP and BSA shape factors were investigated and rationalized in terms of the water structure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1001–1015, 2003     

Scatheless active functionalized poly(p‐phenylene terephthalamide) fibres and their outstanding potential in enhancing interface adhesion with polymer matrix

Exploration of new functionalization approaches to inert rigid fiber, activation inert surface, and enhancing interface adhesion is urgently required for fiber‐based multiphase materials. In this paper, we developed a simple yet efficient method towards active functionalized poly(p‐phenylene terephthalamide) fiber through mussel‐adhesive, self‐polymerization, and successive dipping–drying procedure based on as‐designed detachable equipment. In comparison with current acid etching and high energy radiation methods, the active functional strategy achieves scatheless functional modification to inert rigid fiber. Attribute to π–π conjugation effect, the new active nanolayers integrate rigid fiber and polymer matrix into homogeneous‐like structure. Consequently, the functionalized fiber‐based composites exhibit great mechanical property and desirable field‐responsive ability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43018.     

Entropy–enthalpy compensation in solution properties of solutes at infinite dilution in nonpolar polymers

The knowledge of the Flory–Huggins interaction parameter, χ, between organic liquids and polymers is very important in the study of their miscibility. From the temperature dependency of χ the enthalpy and residual entropy of solution can be determined. In this study literature data of thirty‐two solutes, ranging from alkanes to alcohols, at infinite dilution in isotatic polypropylene, poly(ethyl ethylene), and poly(dimethylsiloxane), were tested and linear entropy–enthalpy compensation was observed. The plot of residual free energy versus enthalpy of solution was also linear, with a lower correlation coefficient than the entropy–enthalpy plot. The range of enthalpy of solution was wider than those of the size corrected free energy of solution. In nonpolar solvents the enthalpy of solution reflected largely the interaction within the solute liquid state, and showed a linear trend with respect to solute cohesive energy density for n‐alcohols. The wide range of enthalpy of solution suggests the use of a two‐dimensional solubility parameter model to correlate the enthalpy of solution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1241–1247, 2007     

Influences of extractant on the hydrophilicity and performances of HDPE/PE‐b‐PEG blend membranes prepared via thermally induced phase separation (TIPS) process

Blending the block copolymer into the membrane matrix is a convenient and efficient way for membrane modification. In this study, HDPE/PE‐b‐PEG membranes were prepared via TIPS process, and the extractant effect was investigated. An interesting finding was that a non‐polar extractant (n‐hexane) was more conducive to the surface enrichment of PEG chains than a polar solvent (ethanol). The reason was deemed to be the combined effect of entropy drive, interfacial energy, and the swelling behavior. Besides, membrane performances related to the surface chemical properties were studied. Results suggested that the prepared blend membranes extracted by n‐hexane showed enhanced hydrophilicity, anti‐fouling property and water flux. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2680–2687, 2013     

Effects of the extractant on the hydrophilicity and performance of high‐density polyethylene/polyethylene‐b‐poly(ethylene glycol) blend membranes prepared via a thermally induced phase separation process

The blending of a block copolymer into the membrane matrix is a convenient and efficient way to modify membranes. In this study, high‐density polyethylene/polyethylene‐b‐poly(ethylene glycol) (PEG) membranes were prepared via a thermally induced phase separation process, and the extractant effect was investigated. An interesting finding was that the nonpolar extractant (n‐hexane) was more conducive to the surface enrichment of the PEG chains than the polar solvent (ethanol). The reason was deemed to be the combined effect of the entropy drive, interfacial energy, and swelling behavior. In addition, the membrane performance related to the surface chemical properties was studied. The results suggest that the prepared blend membranes extracted by n‐hexane showed enhanced the hydrophilicity, antifouling properties, and water flux. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3816–3824, 2013     

Resin II: Thermal degradation studies of terpolymer resins derived from 2,2′‐dihydroxybiphenyl,urea, and formaldehyde

The terpolymer resins have been synthesized by the condensation of 2,2′‐dihydroxybiphenyl with urea and formaldehyde in the presence of 2M HCl as a catalyst and with varying molar proportions of reactants. Elemental analysis, IR, NMR and UV–Visible spectral study, and TGA–DTA analysis characterized the resins. The number average molecular weight was determined by nonaqueous conductometric titrations. Thermal studies of the resins have been carried out to determine their mode of decomposition, activation energy, order of reaction, frequency factor, entropy change, free energy, and apparent entropy change. Freeman–Carroll and Sharp–Wentworth methods have been applied for the calculation of kinetic parameters, while the data from Freeman–Carroll method have been used to determine various thermodynamic parameters. The order of thermal stabilities of terpolymers has been determined using TGA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 227–232, 2006     

The influence of binary drag laws on simulations of species segregation in gas-fluidized beds

Monodisperse drag laws have been traditionally employed in polydisperse systems using ad hoc assumptions due to the lack of adequate drag laws for polydisperse systems. A key component of both continuum and discrete models used to study segregation in gas fluidized beds is the drag law. In this work, both the ad hoc approach and a new drag treatment developed specifically for polydisperse mixtures using lattice-Boltzmann simulations [M.A. Van der Hoef, R. Beetstra, J.A.M. Kuipers, Lattice-Boltzmann simulations of low-Reynolds-number flow past mono- and bidisperse arrays of spheres: results for the permeability and drag force, J. Fluid Mech. 528 (2005) 233–254] are incorporated into a Multi-Phase Particle-in-Cell (MP-PIC) framework to evaluate their impact on simulations of gas-fluidized, binary mixtures. In particular, several systems composed of Geldart group B particles that differ in size and/or density are considered, with special attention paid to axial species segregation at low fluidization velocities. For a system with size difference only, the Van der Hoef et al. [M.A. Van der Hoef, R. Beetstra, J.A.M. Kuipers, Lattice-Boltzmann simulations of low-Reynolds-number flow past mono- and bidisperse arrays of spheres: results for the permeability and drag force, J. Fluid Mech. 528 (2005) 233–254] drag treatment presents a higher degree of mixing than the ad hoc treatment. For a system with size and density differences, where the small particle is the denser and less massive one, the ad hoc treatment predicts a higher degree of mixing than the Van der Hoef et al. [M.A. Van der Hoef, R. Beetstra, J.A.M. Kuipers, Lattice-Boltzmann simulations of low-Reynolds-number flow past mono- and bidisperse arrays of spheres: results for the permeability and drag force, J. Fluid Mech. 528 (2005) 233–254] treatment. For systems with density differences only or both size and density differences where the large particle is the denser one, both drag treatments generate essentially the same segregation profiles. The relative segregation tendencies predicted by each drag treatment is explained through a qualitative analysis of drag force coefficients of each species in the mixture. The simulation results indicate that the drag law treatment plays a crucial role in the qualitative and quantitative nature of segregation predictions at low gas velocities.     

Energy of chemical bonds and spatial energy principles of the hybridization of atom orbitals

Methods for the evaluation of energy directedness of atom orbital hybridization and the calculation of the energy of chemical bonds in simple and complex structures are proposed on the basis of the application of the spatial energy parameter concept. Appropriate calculations and comparisons for 68 compounds were made. The calculation results agreed with the experimental data. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2101–2107, 2006     

Chemical silver plating on polyester/cotton blended fabric

Chemical plating is a metallizing process that can impart unique properties to textile fabrics. It has great potential for use in textile production, especially in the functional and decorative aspects. The present study examined the feasibility of applying chemical silver plating to a polyester/cotton blended fabric (T/C fabric) as well as investigating the properties of the silver‐plated T/C fabric. It was found that chemical silver plating helped to produce T/C fabric with a novel appearance and to improve its performance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4383–4387, 2006     

Excess volume of polymer/solvent mixtures and proposed model for prediction of activity of solvents based on excess volume data

Density measurements were used to evaluate the excess volume of binary mixtures of poly(ethylene glycol) in water and ethanol solvents, poly(propylene glycol) in water and ethanol solvents, and poly(vinyl alcohol) in water solvent at different temperatures for various molecular weights of polymers. The excess volumes were correlated and expressed by a polynomial in terms of the weight fraction of the polymer. The activity of the solvent was expressed in terms of three parts: excess internal energy, excess entropy, and excess volume. The excess volume was derived from the expression obtained in this work, the excess entropy was derived from Flory's lattice model, and the excess internal energy was used as a weight average of the excess volume and entropy parts. The results indicated good agreement between the activity of the solvent calculated by the proposed model and the experimental data. The proposed model has the advantage that using only simple density measurements the activity values that are necessary in the calculation of thermodynamic properties can be evaluated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1219–1227, 2005     

Kinetics of the enthalpy relaxation process for an epoxy network as determined with a peak shift model

The relaxation kinetics of the epoxy network diglycidyl ether of bisphenol A (n = 0) and m‐xylylenediamine were studied with differential scanning calorimetry experimental data with a shift peak model. Nonlinear parameters were calculated with aging experiments. The nonexponential parameter and the apparent activation energy were found from intrinsic cycles. Adam–Gibbs theory was used to provide a molecular interpretation based on the enthalpy relaxation. Different assumptions of the variation of specific heat capacity (c_p) were used to determine the macroscopic molar configurational entropy of the system. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2003–2008, 2005     

Effect of channel size on liquid‐liquid plug flow in small channels

The hydrodynamic properties of plug flow were investigated in small channels with 0.5‐, 1‐, and 2‐mm internal diameter, for an ionic liquid/aqueous two‐phase system with the aqueous phase forming the dispersed plugs. Bright field Particle Image Velocimetry combined with high‐speed imaging were used to obtain plug length, velocity, and film thickness, and to acquire velocity profiles within the plugs. Plug length decreased with mixture velocity, while for constant mixture velocity it increased with channel size. Plug velocity increased with increasing mixture velocity and channel size. The film thickness was predicted reasonably well for Ca > 0.08 by Taylor's (Taylor, J Fluid Mech. 1961;10(2):161–165) model. A fully developed laminar profile was established in the central region of the plugs. Circulation times in the plugs decreased with increasing channel size. Pressure drop was predicted reasonably well by a modified literature model, using a new correlation for the film thickness derived from experimental values. © 2015 American Institute of Chemical Engineers AIChE J, 62: 315–324, 2016     

Cellulose acetate reverse osmosis membranes: Optimization of preparation parameters

Asymmetric cellulose acetate based membranes usually employed in reverse osmosis as well as in separations in aqueous systems can possibly be applied in the so‐called salinity process of energy generation. For these applications, membranes with a relatively high water permeability (sometimes also called water flux) and low salt permeability (or high salt rejection) are required. In this study the authors present the optimization of such membranes, which concerns the preparation parameters. The membranes studied were prepared from a solution whose composition were previously optimized.⁴ The authors concluded that the optimum preparation parameters are as follows: thickness of the liquid film of 100 μm; 30 s allowed for evaporation of the solvent; and temperature of coagulation bath of 0–4°C and 80–85°C as annealing temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 134–139, 2007     

Studies on the surface properties and the adhesion to metal of polyethylene coatings modified with primary aromatic amines

The surface free energy and acid–base characteristics of polyethylene coatings formed on steel in the presence of primary aromatic amines (PAAs) were investigated. PAAs were shown to interact with steel by a donor–acceptor mechanism. An increase in the coating adhesion is realized through chemical and physical bond formation between an adhesive and a substrate with the help of the PAA. The free surface energy of the contact‐to‐metal side of these coatings modified with PAA was shown to grow in parallel with the increase in adhesion. The results correlate with the data on polyethylene surface wetting with nonionic surfactants. Acid–base interactions were found to exert primary control over polyethylene's adhesion to steel. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 388–397, 2001     

Influence of the alkyl tail on the solubility of poly(alkyl acrylates) in ethylene and CO2 at high pressures: Experiments and modeling

Cloud point data to 230°C and 2200 bar are presented for poly(acrylate)–ethylene mixtures. When the length of the alkyl tail is increased, the cloud point curve is shifted towards lower pressure, but this trend switches when going from poly(ethyl hexyl) to poly(octadecyl) acrylate. It is apparent that there is an optimum alkyl tail length that balances energetic acrylate–acrylate, ethylene–ethylene, and ethylene–acrylate interactions and free-volume, entropic effects. Both ethylene–poly(acrylate) and CO₂–poly(acrylate) data are modeled by the Statistical Associating Fluid Theory (SAFT) equation of state. A pseudogroup contribution method is developed for the calculation of the following pure polymer characteristic parameters: m, the number of segments, and v⁰⁰, the volume of a segment. This method cannot be applied for u⁰/k, the attractive energy of a segment, which changes in a nonlinear manner with changes in the structure of the acrylate repeat group. The energy parameter is then calculated from monomer data or fitted directly to one cloud point curve. The experimental data are represented well, even if little predictive power is obtained since a temperature-independent interaction parameter k_ij is needed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1979–1991, 1999     

Thermal aging of polyethylene-co-methyl acrylate elastomer activation energies of physical and physicochemical mechanisms

This article deals with the thermal aging of a polyethylene-co-methyl acrylate elastomer. Six different activation energies have been determined corresponding to the following different mechanisms: surface oxidation, whole bulk oxidation in the case of heterogeneous oxidation, consumption of antioxidant, creep, and relaxation (compression set). Relaxation mechanism has been found to have the lowest activation energy (45 kJ/mol). Dominant chemical modification has been found to have the highest activation energy (119 kJ/mol). The case of heterogeneous oxidation is considered in details: a variation of the activation energy is obtained. The activation energy varies from a constant upper value related to homogeneous oxidation, to a lower value related to the so-called “total heterogeneous oxidation”. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2507–2515, 1997