bluuebunny/crossref_metadata_2025_split huggingface dataset:
A computational fluid dynamic study of a low‐humidity co‐current spray dryer
Authors: Huang Li Xin , Mujumdar A. S. 
Published: May 2007

AbstractBecause spray drying uses high‐temperature gas as the drying medium and the deposits on the wall cannot be avoided in practical spray dryers, the products are subject to degradation by overheating. In order to reduce the degradation of the active components in the dried powder, a low‐dew‐point (LDP) spray dryer is proposed and evaluated via a computational fluid dynamic (CFD) model. A cylinder‐on‐cone spray dryer with pressure nozzle is investigated numerically with a commercial CFD code. The effects of low inlet air humidity and temperature on the gas flow patterns, droplet trajectories and overall dryer performance are investigated. The volumetric evaporation rate values, volumetric heat transfer intensity and thermal energy consumption per unit evaporation of water were computed and compared for evaporation of pure water in a spray chamber 2.215 m in diameter with a cylindrical top section 2.0 m high and a bottom cone 1.725 m high. Although a smaller product capacity is obtained compared with the normal spray dryer, it has advantages for drying heat‐sensitive materials. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.
Through drying characteristic of oil palm empty fruit bunch (EFB) fibers using superheated steam
Authors: Hasibuan Rosdanelli , Wan Daud Wan Ramli 
Published: May 2007

AbstractEmpty fruit bunches (EFB) of the oil palm have great potential to be used as industrial fibers in various industries, such as fiber board, mattress and cushion, erosion controller, thermoplastic filler, paper, acoustics control, sound insulator, and animal feed industries. A rotary drum dryer with a flue gas drying medium has been conventionally used to dry EFB fibers. However, this drying system tends to produce highly entangled and blackened fiber. Furthermore, the uneven contact between the flue gas and fiber in the rotary dryer may cause nonuniformity in the moisture content of the product. To overcome this problem, the present work uses superheated steam as the drying medium for EFB fiber drying. The drying experiments were carried out at the following conditions: atmospheric pressure; temperature range 112–172 °C; steam superficial velocity in the range 0.14‐4.3 m/s, distance from steam nozzle to EFB in the range 50–200 mm; and size of holes on plate in the range 10–200 mesh. The initial fiber moisture content was in the range 0.96‐1.46 kg/kg dry basis. The mass loss of EFB fiber during the drying process was periodically measured using an analytical balance connected directly to the wire mesh plate when the steam was diverted momentarily so that the effect of momentum transfer between the steam and the sample holder is minimized. In the temperature range 112–172 °C and at atmospheric pressure, the equilibrium moisture content isotherm is found to follow an exponential equation with coefficient ke = 15.365 kg/kg, ne = —0.001 °C−me and power index me = 1.869. It was found that for maximum moisture removal, the temperature and steam superficial velocity was 142 °C and 0.39 m/s, respectively. The effect of steam velocity is greater than that of steam temperature in decreasing the moisture content. The drying rate initially increases to a maximum and then falls off exponentially thereafter. A new drying model was developed for superheated steam for drying of EFB fiber, which is given by MR = 1 − atnexp(−ktm). The increasing drying rate is largely described by the exponential term with the coefficient k having values ranging from 1.945 to 5.351 s−n and the index m having values ranging from − 0.843 to 1.198. The falling drying rate is largely described by the power law term with the coefficient a ranging in value from 0.453 to 1.027 s−m and the power index n ranging in value from 0.0415 to 0.317. The drying is best carried out with the plate at a distance of 150 mm from the sample holder containing a 50 mesh plate. The superheated steam through the drying system can successfully reduce the moisture content by almost 100% in 15 min without steam condensation during the drying process. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.
Acid rock drainage formation and treatment: a review
Authors: Egiebor Nosa O. , Oni Ben 
Published: May 2007

AbstractThe exploitation of coal and metallic mineral resources worldwide invariably results in the production of large quantities of overburden, gangue, and tailings materials containing significant amounts of sulfide minerals. These sulfide minerals, which include sphalerite, chalcopyrite, galena, and other complex sulfides, are often disseminated in pyrite, which is the most abundant sulfide mineral in the earth's crust. Once exposed to water and oxygen through mining and mineral processing operations, these sulfides become immediately susceptible to chemical and biochemical oxidation with the consequent production of highly acidic, metal‐laden leachates, which are generally referred to as acid rock drainage (ARD) or acid mine drainage (AMD). This ARD production, which can be sustained for hundreds of years, has become the single biggest environmental problem facing the mining and mineral industry. Untreated acid rock drainage leads to serious contamination of large areas of land, as well as surface and ground water resources. The seriousness of the problem has led to major research efforts to find solutions. However, effective ARD treatment and prevention solutions have eluded the scientific community over the past decades. This paper presents a detailed review of the current state of scientific knowledge with regard to the magnitude of the problem, the chemistry and mechanism of sulfide mineral oxidation and ARD formation, the role of microorganisms in ARD formation process, and the proposed approaches for the treatment, control, and prevention of ARD formation. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.
Grafting of poly (methyl acrylate) onto sulfite pulp fibers and its effect on water absorbance
Authors: Jain Vaibhav , Xiao Huining , Ni Yonghao 
Published: May 2007

AbstractTo prepare super water absorbent hydrogels of wood cellulose fibers, poly (methyl acrylate) (PMA) was copolymerized onto softwood sulfite pulp fibers using free radical initiator followed by alkaline hydrolysis. Ceric ammonium nitrate (CAN) was used as the free radical initiator. Effects of various parameters such as fiber concentration, monomer/pulp (M/pulp) ratio, CAN concentration, and reaction time on the grafting yield and on other grafting parameters were investigated. The graft conversion was the same from low to medium fiber concentration. The amount of initiator required was found to be independent of fiber concentration to achieve maximum grafting yield. Different fiber fractions (classified based on their length) have no effect on the grafting yield. The evidence of graft copolymerization was determined by using ATR‐IR spectroscopy. The X‐ray diffraction (XRD) analysis shows that grafting takes place both in amorphous and crystalline regions of cellulose fibers and the decrease in crystallinity of the grafted fibers with an increase in grafting yield was confirmed. The surface morphology of the PMA‐g‐cellulose was characterized by scanning electron microscopy (SEM). The water retention value of the hydrolyzed grafted pulp was determined based on a centrifugation technique. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
High performance liquid chromatography study of water‐soluble complexes and covalent conjugates of polyacrylic acid with bovine serum albumin
Authors: Akkiliç Namık , Mustafaeva Zeynep , Mustafaev Mamed 
Published: May 2007

AbstractPolycomplex formation of bovine serum albumin (BSA) and polyacrylic acid (PAA) was studied by pH titration, fluorescence, and HPLC methods in water solutions. It was shown that the complex formation and the solubility (phase state) of the polycomplexes depended on pH of the solutions and ratio of the components. The stability of PAA‐BSA complexes was negligibly weak when pH = 6.0–7.0 [pH > pI (isoelectric pH)]. Stable water‐soluble polycomplexes formed at pH = pI (pH 5.0) in a wide range of nBSA/nPAA ratios (0.05–50) and coexisted with free protein molecules at the higher ratios of components. Existence of water‐soluble and insoluble PAA‐BSA complexes has been observed at pH ≤ 4.5. The soluble to insoluble state transition of polycomplexes has been confirmed and binding mode of polyelectrolytes to proteins was assumed dependent on the ratio of components as a result of formation of soluble polycomplexes, complex coacervation, or amorphous precipitates. Soluble complexes were formed as fully homogenized mixtures. Fraction composition of the mixtures and insoluble complexes depended on the protein/polymer ratio and over the critical protein/polymer ratio, the soluble polycomplexes coexisted with free BSA molecules. On the other hand, the comparision of covalent conjugate formation and complexation of PAA with BSA has been revealed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Lanthanide triflates as curing initiators for solid DGEBA resin: Thermal and mechanical characterization
Authors: García S. J. , Serra A. , Suay J. 
Published: May 2007

AbstractA new class of cationic initiators, lanthanide triflates, has been studied in the curing of diglycidyl ether of bisphenol‐A (DGEBA). Two metal salts (Erbium and Ytterbium (III) trifluoromethanesulfonate) in various proportions (0.5, 1, and 2 parts per hundred of resin) have been used and the thermal and mechanical properties of the thermosets compared to a common solid epoxy system (crosslinked with o‐tolylbiguanide). The kinetics of these processes has been evaluated by the isoconversional method that has been proved to be an excellent tool to predict the principal curing parameters (conversion/time/temperature). Their mechanical properties have been evaluated by dynamic mechanical thermal analysis (DMTA), stress‐strain curves, impact resistances and adhesion to metallic substrates, and the thermal characteristics were measured by calorimetry (DSC) and thermogravimetry (TGA). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
A novel approach to the interpretation and prediction of solvent effects in the synthesis of macroporous polymers
Authors: Scheler Stefan 
Published: May 2007

AbstractA trivariate interpolation technique, the modified Shepard's method, was applied for the first time to explain and predict various properties of macroporous polymers from the Hansen solubility parameters of the porogens employed for polymerization. Highly crosslinked polymers and copolymers were prepared from ethylene glycol dimethacrylate and methacrylic acid by free‐radical polymerization with 30 different porogenic solvents. Instead of the spherical model used by Hansen, detailed three‐dimensional maps were computed to represent the measured properties in a δd–δp–δh diagram (where δd, δp, and δh are the Hansen solubility parameters according to the three types of bonding forces: dispersion, polar, and hydrogen‐bonding, respectively). This method was able to detect unapparent correlations between the different polymer properties, thus providing a better understanding of the pore‐formation process. An important finding was the crucial role of the initiator solubility and its partitioning between the solution and the polymer surface, which proved to be key factors for the explanation of many contradictory solvent effects. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Preparation and characterization of 2‐hydroxyethyl methacrylate‐based porous copolymeric particles
Authors: Fang Dongyu , Pan Qinmin , Rempel Garry L. 
Published: May 2007

Abstract2‐Hydroxyethyl methacrylate was copolymerized with three different comonomers, methyl methacrylate (MMA), styrene (St), and N‐vinyl‐2‐pyrrolidone (NVP), respectively, to prepare porous particles crosslinked using ethylene glycol dimethacrylate (EGDMA) in the presence of an organic solvent, 1‐octanol (porogen), by means of suspension copolymerization in an aqueous phase initiated by 2,2‐azobisisobutyronitrile. Nano‐pores were observed in the particles. The pore size and the swelling properties of these particles can be controlled by changing comonomers or adjusting the crosslinker or porogen concentration. A lower crosslinker or porogen concentration favors generating smaller pores, whereas a higher concentration of a hydrophilic comonomer, higher concentration of crosslinker, and higher porogen volume ratio promote the generation of larger pores. In addition, the effects of the porous characteristics on the swelling properties were explored. The swelling capacity of the porous particles is reduced with the increase in the crosslinker concentration; however, there is a critical porogen volume ratio, in which the maximal swelling capacity is reached. Higher porosity in the particles and higher amount of hydrophilic comonomer favor a higher swelling capacity of the particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Preparation and pervaporation performances of fumed‐silica‐filled polydimethylsiloxane–polyamide (PA) composite membranes
Authors: Tang Xiaoyu , Wang Ren , Xiao Zeyi , Shi Er , Yang Jing 
Published: May 2007

AbstractFumed‐silica‐filled polydimethylsiloxane (PDMS)–polyamide (PA) composite membranes were prepared by the introduction of hydrophobic fumed silica into a PDMS skin layer. The cross‐sectional morphology of these filled composite membranes was observed with scanning electron microscopy. Their pervaporation performances were tested with aqueous ethanol solutions at 30, 35, and 40°C. Increasing the amount of the fumed silica resulted in significantly enhanced ethanol permeability of the membranes. When the content of the fumed silica in the PDMS skin layer was 20 wt %, the ethanol permeability increased to nearly twice that of the unfilled PDMS–PA composite membrane. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Facile synthesis of dendronized polyamides with chloromethyl groups in the periphery and some properties
Authors: Liu Meihua , Xu Weijian , Xu Xiaocong , Lu Yanbing 
Published: May 2007

AbstractA novel dendronized aromatic polyamide with a polyamide backbone and chloromethylene‐end‐functionalized polyamide dendrons is reported for the first time. An attempt at a one‐pot synthesis of end‐functionalized dendronized polymers with a macromonomer strategy without protection and deprotection procedures is also reported for the first time. The results from Fourier transform infrared and NMR spectral analysis indicated that perfect coverage of the chloromethyl groups in the periphery of the resulting polymers was obtained. Data from gel permeation chromatography analysis showed a typical weight‐average molecular weight (Mw) of 76,678 and a polydispersity of 2.44 for the first‐generation polymers and an Mw of 41,554 and a polydispersity of 2.74 for the second‐generation polymers. The solubility in solvents for the resulting polymers was improved remarkably because of the introduction of the dendritic fragments and the existence of the periphery functional groups. Both the glass‐transition temperature and onset decomposition temperature decreased versus those of the linear aromatic polyamides, but the 50% weight loss temperature was still up to 723°C. The X‐ray diffractograms indicated only an amorphous peak in the wide‐angle region of 24–25°. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Fe(II) adsorption onto natural polymers derived from low‐grade lignites
Authors: Tarlan Esra , Ahmetli Gulnare 
Published: May 2007

AbstractIn comparison with conventional chemical treatment methods for Fe(II) ions, adsorption and ion exchange are considered more easily applicable and economical, depending on the material used. Polymeric materials are the examples used in these commonly applied removal processes. In this study, the adsorption of Fe(II) ions from aqueous solutions onto two different natural polymers, insoluble humic acids (IHAs) extracted from low‐grade lignites from Beysehir and Ermenek (in the central Anatolia region, Konya, Turkey), was investigated. The IHAs were synthesized through a series of acid–base reactions, and the obtained precipitates were chemically stable and had about 40% humic matter together with functional carboxyl and hydroxyl groups. The effects of the time and initial metal concentration on the effectiveness of the IHAs for Fe(II) adsorption were determined through batch experiments; the adsorption isotherms and capacities were calculated. The IHAs were effective, with capacities of 59 mg/g for the Beysehir IHA and 57 mg/g for the Ermenek IHA, for Fe removal under neutral pH conditions. The adsorption followed mainly a Freundlich isotherm for both IHAs, and the calculated adsorption rates were 0.86 for the Beysehir IHA and 0.81 for the Ermenek IHA. This indicated that the effectiveness of the Beysehir IHA was slightly higher than that of the Ermenek IHA. The results confirmed the real possibility of the practical application of IHAs for the separation of Fe(II) in aqueous systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Effect of an organic dicarboxylic acid salt on fractionated crystallization of polypropylene droplets
Authors: Jin Y. , Hiltner A. , Baer E. 
Published: May 2007

AbstractThe effect of a particulate nucleating agent on fractionated crystallization of polypropylene (PP) was studied. A novel method utilizing breakup of PP nanolayers was used to obtain a dispersion of PP droplets in a polystyrene (PS) matrix. An assembly with hundreds of PP nanolayers alternating with thicker PS layers was fabricated by layer‐multiplying coextusion. The concentration of an organic dicarboxylic acid salt (HPN) nucleating agent in the coextruded PP nanolayers was varied up to 2 wt %. When the assembly was heated into the melt, interfacial driven breakup of the thin PP layers produced a dispersion of PP particles in a PS matrix. Analysis of optical microscope images and atomic force microscope images indicated that layer breakup produced a bimodal particle size distribution of submicron particles and large, micron‐sized particles. Almost entirely submicron particles were obtained from breakup of 12 nm PP layers. The fraction of PP as submicron particles dropped dramatically as the PP nanolayer thickness increased to 40 nm. Only large, micron‐sized particles were obtained from 200 nm PP nanolayers. The crystallization behavior of the particle dispersions was characterized by thermal analysis and wide angle X‐ray diffraction. Only part of the PP was nucleated by HPN. It was found that HPN was not effective in nucleating the population of submicron particles. The particulate HPN was too large to be accommodated in the submicron PP particles. On the other hand, the amount of nucleated crystallization qualitatively paralleled the fraction of PP in the form of large, micron‐sized particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Effect of cavitation on the plastic deformation and failure of isotactic polypropylene
Authors: Na Bing , Lv Ruihua 
Published: May 2007

AbstractTo clarify the effect of cavitation, which is mostly induced by crystalline phase, on the plastic deformation and failure of isotactic polypropylene, solid‐state annealing at 160°C for 1.5 h is adopted to change the crystalline phase only while the amorphous phase keeps nearly intact. With aid of a special video setup, the relation of true stress and strain as well as the evolution of volume strain with axial strain has been derived. Enhancing crystalline phase due to annealing increases the yield stress and volume strain simultaneously. Moreover, the strain corresponding to steep increasing of volume strain is comparable with that related to yield, indicating that cavitation at early stage is accompanied with process of yield. With knowledge of toughness derived from impact tensile stretching and essential work of fracture (EWF), respectively, the relationship between cavitation and toughness has been correlated to some degree. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Structure control of polyphenylene sulfide membrane prepared by thermally induced phase separation
Authors: Ding Huaiyu , Zhang Qiang , Wang Fuming , Tian Ye , Wang Lihua , Shi Yanqiao , Liu Biqian 
Published: May 2007

AbstractPorous membranes were prepared through thermally induced phase separation (TIPS) of polyphenylene sulfide (PPS)/diphenyl ketone mixtures. The phase diagram of PPS/diphenyl ketone system was drawn by cloud point temperature and dynamic crystallization temperature. SEM images and porosity were used to characterize PPS membrane structures. According to the analysis of phase diagram, three main effecting factors including polymer concentration, cooling rate, and nucleating agent could control the pore structure and pore size for the preparation of symmetry and asymmetry membranes. The experimental results are coincident with the theory prediction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Fracture surface morphology in thermosets modified with hollow microspheres
Authors: Kim Ho Sung 
Published: May 2007

AbstractFracture surface morphology in relation with toughening of thermosets modified with hollow microspheres was studied. Two different toughening methods were employed—one was with (MEH) and the other without (ME) compressive residual stresses around microspheres, respectively. The compressive residual stresses were to increase effective stress intensity factor. Various conditions arising from toughening method, properties of constituent materials, bonding between matrix and microspheres, relativity between bonding and microsphere strengths, and plane stress/strain were derived for part of generalization of fracture surface morphology. Mohr circle representations were employed for relative stress components analysis. New deformation mechanisms contributing to toughening were proposed. A major difference in toughening mechanism between ME and MEH methods was found to be in the location of plastic deformation under plane strain. The plastic deformation of ME was dominantly in matrix and appeared in the form of matrix cavitation. In the case of MEH, it was dominantly in microspheres. It was suggested that compressive residual stress promotes plastic deformation of microspheres caused by “extrusion” effect. The microsphere deformation in MEH was found also under plane stress although it was not as much as under plane strain. Matrix cavitation in ME under plane stress, however, was not found. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Thermal decomposition of copolymers used in dental resins formulations photocured by ultra blue IS
Authors: Rigoli Isabel C. , Cavalheiro Carla C. S. , Neumann Miguel G. , Cavalheiro Éder T. G. 
Published: May 2007

AbstractKinetics of thermal decomposition of acrylates copolymers used in dental resins formulations were studied with dynamic thermogravimetric analysis experiments. The kinetic parameters, including activation energy, pre‐exponential factor, and 60 min half‐life temperature, which were calculated by the Flynn and Wall method, are presented. The results indicate that thermal decomposition of the material occurred in three different stages characterized by different mechanism. These three events were separated and the kinetics parameters were determined. The loss mass was observed in the onset of the thermal decomposition for the all of copolymers studied. When the copolymers were submitted to thermal treatment before of thermal analysis was not observed the loss mass in the beginning of the process. The analysis of intermediates by GC of the condensed material extracted after thermal treatment at TB copolymers showed the presence of the methacrylic acid and 2‐hydroxyethyl methacrylate, which are products of decomposition of BisGMA and triethyleneglycol dimethacrylate monomers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007