bluuebunny/crossref_metadata_2025_split huggingface dataset:
High solids content emulsions. I. A study of the influence of the particle size distribution and polymer concentration on viscosity
Authors: Schneider M. , Claverie J. , Graillat C. , McKenna T. F. 
Published: August 2002

AbstractAn experimental and modeling study was carried out to understand the relationship between the viscosity of a multimodal latex and its particle‐size distribution (PSD) and polymer concentration. This study illustrates the inadequacy of existing models in predicting the viscosity of complex latices. It is shown that the latex viscosity at a fixed shear rate is very sensitive to the polymer concentration at high solids content and to the PSD. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1878–1896, 2002; DOI 10.1002/app.10511
Preparation and characterization of cation exchangers from agricultural residues
Authors: Nada A. M. A. , Eid M. A. , El Bahnasawy R. M. , Khalifa M. N. 
Published: August 2002

AbstractCation‐exchange systems were prepared by phosphorylation of some lignocellulosic materials, namely, rice straw, cotton stalks, and bagasse. The effect of the particle size of the lignocellulosic materials as well as their chemical constituents on the phosphorylation process was studied by the determination of the phosphorus content of the prepared ion‐exchange material. Phosphorus was determined using inductively coupled plasma atomic emission spectrometry. Optimization of the phosphorylation reaction was achieved by studying the effect of the different experimental parameters, namely, the reaction time, temperature, and amount of phosphorus oxychloride added, on the phosphate content of the reaction product. The treatment of the lignocellulosic material with sodium hydroxide was found to improve its phosphorylation. The cation‐exchange efficiency of the produced phosphated material toward Cd2+, Co2+, Cr3+, Cu2+, Fe3+, Ni2+, Pb2+, and Zn2+ was examined. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 792–800, 2002
Hydrogenation of low molar mass OH‐telechelic polybutadienes catalyzed by homogeneous Ziegler nickel catalysts
Authors: Šabata S. , Hetflejš J. 
Published: August 2002

AbstractTwo types of low molar mass, medium vinylic polybutadienes containing 2‐hydroxypropyl and 2‐hydroxyethyl end groups were hydrogenated in the presence of several homogeneous Ziegler Ni catalysts prepared by using Ni(acac)2 and Ni(2‐ethylhexanoate)2 as metal precursors and BuLi, Li adduct to a diene and Et3Al as activators. The catalytic efficiency of these systems determined by rate measurements showed that the best results can be achieved with the Ni(2‐hexanoate)2 + Li‐diene (Ni : Li mol ratio = l : 8–10) catalyst in the solvents commonly used in the synthesis of these polyalkadienes by anionic polymerization of 1,3‐butadiene. As found by the kinetic study, the hydrogenation carried out under mild reaction conditions (temperatures of 10–35°C, hydrogen pressure of 72–178 kPa, Ni concentration of 2.1–10.0 mmol/dm−3) was the first order in the OH‐polybutadiene and hydrogen and, over narrow range of catalyst concentrations (4.3–10.0 mmol Ni/dm−3), also in the catalyst. The activation energy of the hydrogenation estimated from the Arrhenius plot was 42 kJ/mol. Changes in the relative proportion of 1,2‐, cis‐1,4‐, and trans‐1,4‐CC units of the polymer during hydrogenation indicate the selectivity of the catalyst to the 1,2‐hydrogenation. The ease of the addition of hydrogen to the internal CC unsaturation was found to be opposite to that usually observed (trans > cis). The present low‐pressure hydrogenation of both types of telechelic OH‐polybutadienes proceeds with full retention of the average OH functionality and affords the saturated polymers, the residual CC unsaturation of which (<1%) has so far been usually achieved by high‐pressure hydrogenations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1185–1193, 2002
Preparation of semi‐interpenetrating polymer networks composed of silk fibroin and poly(ethylene glycol) macromer
Authors: Kweon H. Y. , Park S. H. , Yeo J. H. , Lee Y. W. , Cho C. S. 
Published: August 2002

AbstractSemi‐interpenetrating polymer networks (SIPNs) composed of silk fibroin (SF) and a poly(ethylene glycol) (PEG) diacrylate macromer were synthesized and characterized. The conformation of SF in SIPNs was changed from a random coil to a β‐sheet structure by formation of SIPNs with PEG, while the crystalline structures of SF and PEG in SIPNs was not changed. The decomposition temperature of SF in the SIPNs was inner‐shifted, an indication of SIPN formation between the SF and the PEG macromer. The tensile strength and elongation of the SIPNs were much higher than were those of SF itself or the SF/PEG blend and increased with an increase of the PEG content. The equilibrium water content of SF was remarkably increased by formation of SIPNs with PEG due to the hydrophilic property of PEG. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1848–1853, 2001
Membrane transport of organics. III. Permeation of some carboxylic acids through bipolar polymer membrane
Authors: Wódzki Romuald , Nowaczyk Jacek 
Published: August 2002

AbstractThe permeation of acetic (AA), propionic (PA), lactic (LA), oxalic (OA), citric (CA), and tartaric (TA) acids through the bipolar ion‐exchange membrane Neosepta BP‐1 (Tokuyama Corp.) was studied. It was found that the fluxes (J, mol cm−2 s−1) and mass‐transfer coefficients (k, cm s−1) increase in the following order: CA < OA < LA < TA < PA ≤ AA. The transport processes in the Neosepta BP‐1 membrane are concentration‐dependent and can be described phenomenologically using I‐Fick's law for diffusion. The permeation phenomena correspond to the solution–diffusion model similarly as to the permeation of carboxylic acids through strongly acidic cation‐exchange membranes. However, in competitive AA–PA transport experiments, typically for strongly basic membranes, the separation ability of the BP‐1 membrane with a preference toward AA was observed. The selectivity coefficients α calculated as the ratio of the respective mass‐transfer coefficients vary in the range from 1.31 ± 0.2 to 2.1 ± 0.6. These values depend on the feed composition and the system arrangement, which means that α is always higher for the system with the anion‐exchange layer is in contact with a feed solution. Rather low fluxes of PA, AA, and other acids, as compared to some monopolar membranes (Neosepta AFN‐7, Nafion‐120, Flemion), are promising for the application of the bipolar membrane in an electrodialytic separation of carboxylic acids from their aqueous solutions or mixtures. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2705–2717, 2001
Processing and properties of thermoplastic starch and its blends with sodium alginate
Authors: Souza Roberta C. R. , Andrade Cristina T. 
Published: August 2002

AbstractViscosity measurements were carried out on corn starch (CS) and CS–sodium alginate (SA) suspensions at low levels of SA [1 to 10% (w/w)], as a function of temperature. The addition of SA caused the granular CS gelatinization process to occur at a lower onset temperature. CS and CS–SA mixtures were extruded in single‐ and twin‐screw extruders, with 15% glycerol and different water contents. Processing of plasticized CS–SA mixtures required lower temperatures, which is consistent with the viscosity results. Homogeneous and flexible extrudates were obtained by processing in a twin‐screw extruder. Samples in the composition range between 0 and 10% (w/w) SA were examined using tensile tests as a function of water content. Mechanical properties were dependent on the water content and on the SA composition. A significant increase in the Young's modulus value was observed for the blend containing 1% SA. Dynamic mechanical analysis was carried out for CS and CS–SA blends. Two transitions were detected in the temperature range –80 to 150°C. Scanning electron microscopy was used to examine the morphology of the extruded samples. The surfaces of the films were homogeneous, which demonstrated that the CS granules in all samples were characteristically destructured under the conditions used in processing. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 412–420, 2001
NR–EPDM covulcanization: A novel approach
Authors: Ghosh Arup Kumar , Debnath Subhas Chandra , Naskar Nityananda , Basu Dipak Kumar 
Published: August 2002

AbstractBis(diisopropyl)thiophosphoryl disulfide (DIPDIS) was used successfully as a novel coupling agent cum accelerator to co‐vulcanize the elastomer blend comprising highly unsaturated natural rubber (NR) and ethylene propylene diene rubber (EPDM) of low unsaturation content. The blend vulcanizates produced exhibit improved physical properties that can be further enhanced by implementing a two‐stage vulcanization technique, as well as by judicious selection of the NR‐to‐EPDM ratio. The results indicate coherency and homogeneity in the blend composition of two‐stage vulcanizates. The cure‐rate mismatch problem could thus be solved through the formation of rubber‐bound intermediates with a multifunctional rubber additive (i.e., DIPDIS), thereby restricting the curative migration from lower to highly unsaturated rubber. The blend morphology as revealed by SEM studies accounts for significant improvement in physical properties, particularly in two‐stage vulcanizates. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 800–808, 2001
Mechanical properties of uncrosslinked and crosslinked linear low‐density polyethylene/wax blends
Authors: Krupa I. , Luyt A. S. 
Published: August 2002

AbstractThe mechanical properties of uncrosslinked and crosslinked linear low‐density polyethylene (LLDPE)/wax blends were investigated, using differential scanning calorimetry (DSC), tensile testing, and melt flow indexing. A decrease in the degree of crystallinity, as determined from the DSC melting enthalpies, was observed with an increase in the dicumyl peroxide (DCP) concentration. The Young's modulus increased with increased wax portions, and there was a higher increase for crosslinked blends. The yield stress generally decreased with increased peroxide content. Crosslinking caused an increase in elongation at yield, but increased wax content caused a decrease in elongation at yield. The stress at break generally increased with increasing peroxide content, but it decreased with increased wax content. The elongation at break decreased with an increase in the DCP concentration. Melt flow rate measurements indicated a mutual miscibility in LLDPE/wax blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 973–980, 2001
Thermal degradation behavior of epoxy resin blended with propyl ester phosphazene
Authors: Denq Bar‐Long , Chiu Wen‐Yen , Lin King‐Fu , Fuh Ming‐Ren Steve 
Published: August 2002

AbstractThe study was focused on the thermal degradation behavior of epoxy resins (EP) blended with propyl ester phosphazene (FR). The analysis studied the evolved gas and the residual char yield using different techniques. The results showed that pure epoxy resin and their blends were all a one‐stage thermal degradation reaction. The major degradation temperature of blends was lower than the temperature of pure epoxy resin, but the residual char yield of epoxy blends at 550°C was higher than that of pure epoxy resin. FR could accelerate the production of small molecules such as acetone, phenol, and isopropyl phenol during thermal degradation process. Honeycomb structure compounds were also formed in the residual char of epoxy and its blends. Additionally, elemental analysis of the residual char yield showed that phosphorus was a residual element, and other elements mostly diffused to the evolved gas. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1161–1174, 2001
Effect of diluents on membrane formation via thermally induced phase separation
Authors: Matsuyama Hideto , Teramoto Masaaki , Kudari Shunsuke , Kitamura Yoshiro 
Published: August 2002

AbstractThe effect of diluents on isotactic polypropylene (iPP) membrane formation via thermally induced phase separation was investigated. The diluents were methyl salicylate (MS), diphenyl ether (DPE), and diphenylmethane (DPM). The cloud‐point curve was shifted to a lower temperature in the order iPP–MS, iPP–DPE, and iPP–DPM, whereas the crystallization temperature was not influenced so much by diluent type. Droplet‐growth processes were investigated under two conditions: quenching the polymer solution at the desired temperature and cooling at a constant rate. Although droplet sizes were in the order iPP–MS, iPP–DPE, and iPP–DPM in both cases, the difference was more pronounced with the constant cooling rate condition. Scanning electron microscopy indicated that interconnected structures were obtained when the polymer solution was quenched in ice water. The effect of the diluents on these structures was observed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 169–177, 2001
Elasticity of ion‐exchange resin beads in solvent mixtures
Authors: Tiihonen Jari , Markkanen Ismo , Laatikainen Markku , Paatero Erkki 
Published: August 2002

AbstractThe effect of the solvent composition on the elasticity of strong and weak cation‐ and anion‐exchange resin beads was studied. Poly(styrene‐co‐divinylbenzene) resins containing sulfonic acid or quaternary ammonium groups and an acrylic acid resin crosslinked with divinylbenzene were immersed in water, NaCl solutions, or aqueous alcohol solutions and the shear modulus was measured with a uniaxial compression method. The elastic data were compared with the swelling properties. In pure water the shear moduli increased when the crosslink density, counterion valence, counterion size, and functional group size increased. Two additional phenomena in the elastic behavior were observed when the swelling degree of the resins was changed by the addition of alcohol or salt. A decrease of the modulus was observed when moving from the fully swollen state to a less swollen state, and a steep upturn of the modulus took place at a characteristic swelling region. The depth of the minimum and the location of the transition from the rubbery to the glassy state depended on the characteristics of the resins. The finite expansibility of the polymer chains and the glass transition explained these findings. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1256–1264, 2001
Thermal and dynamic mechanical behavior of ethylene/norbornene copolymers with medium norbornene contents
Authors: Forsyth John F. , Scrivani Teresa , Benavente Rosario , Marestin Catherine , Pereña José M. 
Published: August 2002

AbstractA range of ethylene/norbornene copolymers were synthesized using the commercially available rac‐Et(Ind)2ZrCl2 metallocene catalyst. A large window of norbornene contents, between 30 and 55 mol % was used to facilitate the interpretation of the results. The polymers were characterized by means of wide‐angle X‐ray scattering, differential scanning calorimetry, and dynamic mechanical thermal analysis. The X‐ray diffractograms showed two amorphous halos, the low‐angle one increasing in the intensity with norbornene content. Calorimetric and dynamic mechanical results led to a linear relation between the glass transition temperature and the norbornene content. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2159–2165, 2001
Characterization and structural modification of ammonic lignosulfonate by methylolation
Authors: Alonso M. V. , Rodríguez J. J. , Oliet M. , Rodríguez F. , García J. , Gilarranz M. A. 
Published: August 2002

AbstractThe methylolation of softwood and hardwood lignosulfonates was studied. Six different lignosulfonate samples (three from hardwoods and three from softwoods) were characterized in order to assess their suitability for methylolation. The techniques employed in characterization were UV/vis spectroscopy, Fourier transform infrared (FTIR), and 1H‐nuclear magnetic resonance (1H‐NMR). The best properties were shown by softwood ammonium lignosulfonate (LAS), which was used to optimize the operation conditions to promote the Lederer–Manasse reaction. The methylolation variables studied were the sodium hydroxide‐to‐lignin molar ratio, the formaldehyde‐to‐lignin molar ratio, time, and temperature. The reaction was followed by the changes in the concentration of free formaldehyde. IR and NMR spectra of nonmodified and modified samples were used to study the structural changes. Under optimum operation conditions, softwood lignosulfonates showed higher reactivity toward formaldehyde than did hardwood lignosulfonates. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2661–2668, 2001
Surface modification of poly(tetrafluoroethylene) with pulsed hydrogen plasma
Authors: Inagaki N. , Tasaka S. , Narushima K. , Teranishi K. 
Published: August 2002

AbstractSurface modification of polymers by pulsed plasma has been investigated to minimize degradation reactions occurring at the same time as the surface modification reactions. The hydrogen radical, ion, and electron concentrations in the hydrogen plasma were simulated as a function of the elapsed time after turning off the discharge. The contact angle measurement showed that hydrogen plasma treatment, regardless of pulsed or continuous plasma, led to degradation reactions as well as defluorination and oxidation on PTFE surfaces. The degradation reactions of PTFE chains initiated by the pulsed hydrogen plasma were not as vigorous as those by the continuous hydrogen plasma. A combination of the on‐time/off‐time of 30/270μs in the pulsed hydrogen plasma was efficacious in modifying PTFE surfaces. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 340–348, 2002
Rigid thermosetting liquid molding resins from renewable resources. II. Copolymers of soybean oil monoglyceride maleates with neopentyl glycol and bisphenol A maleates
Authors: Can E. , Küsefoğlu S. , Wool R. P. 
Published: August 2002

AbstractSoybean oil monoglycerides (SOMG), obtained by the glycerolysis of soybean oil, were reacted with maleic anhydride to produce SOMG maleate half esters. The copolymers of the SOMG maleates with styrene produced rigid thermosetting polymers. The dynamic mechanical analysis (DMA) of this polymer showed a glass‐transition temperature (Tg) around 133°C and a storage modulus (E′) value around 0.94 GPa at 35°C. The tensile tests performed on this polymer showed a tensile strength of 29.36 MPa and a tensile modulus of 0.84 GPa. Mixtures of SOMG with neopentyl glycol (NPG) and SOMG with bisphenol A (BPA) were also maleinized under the same reaction conditions and the resulting maleates were then copolymerized with styrene. The resulting polymers were analyzed for their mechanical properties. The Tg of the copolymers of the SOMG/NPG maleates with styrene was 145°C and the E′ value at 35°C was 2 GPa. The tensile strength of this polymer as calculated from the stress–strain data was 15.65 MPa and the tensile modulus was 1.49 GPa. The Tg of the copolymers of SOMG/BPA maleates, on the other hand, was found to be around 131°C and the E′ value was 1.34 GPa at 35°C. The changes observed in the mechanical properties of the resulting polymers with the introduction of NPG maleates and BPA maleates to the SOMG maleates can be explained by the structural changes on the polymer backbone. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 972–980, 2002
Leaping lopsided: A review of the current hypotheses regarding etiologies of limb malformations in frogs
Authors: Loeffler I. Kati , Stocum David L. , Fallon John F. , Meteyer Carol U. 
Published: August 2002

AbstractRecent progress in the investigation of limb malformations in free‐living frogs has underlined the wide range in the types of limb malformations and the apparent spatiotemporal clustering of their occurrence. Here, we review the current understanding of normal and abnormal vertebrate limb development and regeneration and discuss some of the molecular events that may bring about limb malformation. Consideration of the differences between limb development and regeneration in amphibians has led us to the hypothesis that some of the observed limb malformations come about through misdirected regeneration. We report the results of a pilot study that supports this hypothesis. In this study, the distal aspect of the right hindlimb buds of X. laevis tadpoles was amputated at the pre–foot paddle stage. The tadpoles were raised in water from a pond in Minnesota at which 7% of surveyed newly metamorphosed feral frogs had malformations. Six percent (6 of 100) of the right limbs of the tadpoles raised in pond water developed abnormally. One truncated right limb was the only malformation in the control group, which was raised in dechlorinated municipal water. All unamputated limbs developed normally in both groups. Three major factors under consideration for effecting the limb malformations are discussed. These factors include environmental chemicals (primarily agrichemicals), encysted larvae (metacercariae) of trematode parasites, and increased levels of ultraviolet light. Emphasis is placed on the necessary intersection of environmental stressors and developmental events to bring about the specific malformations that are observed in free‐living frog populations. Anat Rec (New Anat) 265:228–245, 2001. Published 2001 Wiley‐Liss, Inc.