bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations of recirculation in the bore fluid during hollow fiber spinning
Authors: Su Y. , Lipscomb G. G. , Balasubramanian H. , Lloyd D. R. 
Published: March 2006

AbstractHollow fiber membranes are used widely in membrane separation processes because of their high surface area to volume ratio. Several models have been developed for the hollow fiber spinning process. However, many details of the process are not well understood. In this work, the conservation of mass and momentum equations are solved for isothermal, axisymmetric hollow fiber spinning. In contrast to past work, the conservation equations are solved for both the bore and clad fluids. The two sets of equations are linked by continuity of velocity and stress across the bore–clad interface. Simulation results show an unexpected recirculation region in the bore fluid under certain operating conditions. For a given die geometry, the presence/absence and size of the recirculation region is dependent on the bore‐to‐clad flow rate ratio and bore‐to‐clad viscosity ratio. The appearance of the recirculation region leads to a more rapid decrease of both fiber outer and inner radii after die swell. The predicted changes in fiber radii are in better agreement with experimental observations than predictions from the one‐dimensional thin filament analysis. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Influence of premade and in situ compatibilizers in polypropylene/ethylene–propylene–diene terpolymer thermoplastic elastomeric olefins and thermoplastic vulcanizates
Authors: Naskar K. , Noordermeer J. W. M. 
Published: March 2006

AbstractDuring dynamic vulcanization of polypropylene (PP)/ethylene–propylene–diene terpolymer (EPDM) blends with dicumyl peroxide/triallyl cyanurate, there is a possibility of the generation of in situ graft links at the interface. Three potential compatibilizers (PP‐grafted EPDM, styrene–ethylenebutylene–styrene, and trans‐polyoctenamer) for PP/EPDM blends were first investigated as references to obtain a quantified insight into the effects to be expected from in situ graft links. Only the first compatibilizer showed some compatibilizing action in straight, unvulcanized blends, as evidenced by a slight increase in the tensile strength of the blend and a somewhat smaller EPDM particle size within the PP matrix. Also, dynamic mechanical testing, in particular, the glass‐transition temperatures of the PP and EPDM components, showed some signs of compatibilization. The PP‐grafted EPDM resembled most closely the structures of PP and EPDM. In the spectra obtained with high temperature, solid‐state NMR, there was an indication that PP–EPDM graft links were generated during the dynamic vulcanization process that still remained after the extraction of the free PP phase from the thermoplastic vulcanizate film. NMR relaxation experiments gave further evidence for the graft links formed in situ. In all cases, only qualitative indications could be achieved because of the extremely low number of graft links formed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3877–3888, 2006
Preparation and XPS surface chemical analysis of PS/PU nanocomposites
Authors: Zhu Yan , Zhang Lian‐Meng , Zheng Hua , Sun Duo‐Xian 
Published: March 2006

AbstractAqueous emulsions of anionic polyurethane ionomers, based on polypropylene glycol as soft segment, isophorone diisocyanate as diisocyanate, dimethylolpropionic acid as chain extender and potential ionic center, and triethylamine as neutralizer, were synthesized. They were mixed with styrene monomers to prepare polystyrene–polyurethane (PS/PU) nanocomposites by an evocator. The sizes and distributions of the particles were measured by dynamic light scattering, and the microstructure of the nanocomposites was observed by transmission electron microscope. X‐ray photoelectron spectroscopy (XPS) was used to study the surface characterization of anionic PU and PS/PU nanocomposites. It could be found that the nanoparticles of PU could encapsulate the styrene monomers effectively and the leakage type of every element in PU was not affected by the introduction of Ps. There were more hard segments on the surface of crosslinking PS/PU nanocomposites because of the formation of crosslinking structure and interpenetrating polymer network between PU and PS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3889–3894, 2006
Relationship between the network morphology and properties of commercial vinyl ester resins
Authors: Rodriguez Exequiel , Larrañaga Maider , Mondragón Iñaki , Vázquez Analía 
Published: March 2006

AbstractTwo commercial vinyl ester resins, Derakane 411‐350 (resin D) and Derakane 411‐350 Momentum (resin M), were characterized. Despite the large quantity of publications in the literature about vinyl ester resins, few experimental results have been reported for resin M. The effect of the styrene content on the mechanical properties and morphological structure was studied. An increase in the styrene content produced a network with a low storage modulus in the rubber state and a glass‐transition temperature. The apparent average molecular weight between crosslink points and glass‐transition temperature were slightly higher for resin D than for resin M. The Fourier transform infrared spectra and molecular weight distributions were similar. However, resin M was tougher than resin D, and this may have been due to the closer structure in the fully cured state. Atomic force microscopy was performed for each cured resin and confirmed the difference in the nanostructures. The main reason for the differences in the developed structures was the use of an accelerator, which influenced the final morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3895–3903, 2006
Studies of the curing kinetics and thermal stability of epoxy resins using a mixture of amines and anhydrides
Authors: Jain Ritu , Kukreja Parveen , Narula A. K. , Chaudhary Veena 
Published: March 2006

AbstractThis article describes the curing and thermal behavior of diglycidyl ether of bisphenol A with phthalic anhydride (PA)/pyromellitic anhydride/diaminodiphenyl sulfone (DDS) or a mixture of anhydrides and amines in varying ratios as curing agents. The kinetics of the curing behavior was investigated with a multiple‐rate method. The activation energy of the curing reaction as determined in accordance with Ozawa's method was found dependent on the structure of the anhydride and on the ratio of amines to anhydrides. The activation energy was highest with sample DP3 (0.25 : 0.75) and DM3 (0.25 : 0.75). We evaluated the thermal stability of epoxy resin, cured isothermally, by recording thermogravimetric traces in a nitrogen atmosphere. The char yield was highest for resins cured with a mixture of DDS and PA (0.5 : 0.5) and a mixture of DDS and pyromellitic dianhydride (0.25 : 0.75). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3919–3925, 2006
Bond strength and durabilty behavior of polyurethane‐based Desmodur‐VTKA adhesives used for building materials after being exposed to water‐resistance test
Authors: Uysal Burhanettin , Özçifçi Ayhan 
Published: March 2006

AbstractPolyurethane adhesives are being used increasingly in the construction of furniture frames and buildings. Yet, there is little information available concerning the durability behavior of polyurethane adhesives on various wood species, after being exposed to water‐resistance test. For this purpose, oriental beech (Fagus orientalis L.), oak (Qercus petraea spp.), and scotch pine (Pinus sylvestris lipsky) woods were chosen as test materials and bonded with Desmodur‐VTKA polymarine, according to the procedure of BS EN 204 standards. The shear strength test was applied to the samples, according to the procedure of BS EN 205 standards, before and after immersion in cold water and in hot water, and afterward boiled and boiled recurrently. At the end of the shear test, it was found that Desmodur‐VTKA polymarine had lost its durability. The highest shear strength (10.723 N/mm2) was obtained in oak samples not exposed to water‐resistance test. Owing to dissimilar swelling of Desmodur‐VTKA polymarine and oak, resulting from moisture sorption, oak samples lost 85.6% of its strength after being boiled and boiled recurrently, and gave the lowest shear strength as 1.540 N/mm2. As a result, if Desmodur‐VTKA is used as an adhesive material in the long‐term humidity condition, it cannot be recommended for bonding of wood materials with high density. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3943–3947, 2006
Treatment of polluted water resources using reactive polymeric hydrogel
Authors: Shawky H. A. , El‐Sayed M. H. , Ali A. El‐Hag , Abdel Mottaleb M. S. 
Published: March 2006

AbstractAn experimental work was conducted to study the performance of the already prepared polyvinyl pyrrolidone/acrylic acid (PVP/AAc) copolymer hydrogel to chelate heavy metals from bulk solution. Studies of the binding capacity, adsorption isotherm, and adsorption kinetic experiments showed that PVP/AAc copolymer hydrogel has high binding capacities and good adsorption kinetic properties for the metal ions under investigation. The adsorption isotherms of such metal ions on the copolymer exhibit a Langmuir‐type equation. The chelated copolymers were characterized by FTIR and XRD. Technical feasibility for the uses of the prepared PVP/AAc hydrogel for the treatment of polluted samples; collected from different water resources in Helwan area (Egypt) was investigated. The evaluation of the system was performed by a complete analysis of water samples before and after the treatment process. The results showed a promising possibility for producing water of better quality in the area under investigation, using such prepared hydrogel. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3966–3973, 2006
Superparamagnetic thermoresponsive composite latex via W/O miniemulsion polymerization
Authors: Lin Chia‐Lung , Chiu Wen‐Yen , Don Trong‐Ming 
Published: March 2006

AbstractIn this research, the thermoresponsive composite latex particles were prepared via W/O miniemulsion polymerization. Fe3O4 nanoparticles were homogeneously dispersed inside the poly(NIPAAm‐co‐MAA) latex particles. In the first step, PAA oligomers were used as stabilizers to produce a stable water‐based Fe3O4 ferrofluid, which could mix well with the water‐soluble monomers. In the second step, the Fe3O4/poly(NIPAAm‐co‐MAA) composite latex particles were synthesized via W/O miniemulsion polymerization. This polymerization proceeded in cyclohexane at room temperature, with Span80 as the emulsifier, NIPAAm as the thermoresponsive monomer, MAA as a comonomer with COOH functional groups, and APS/SMBS as the redox initiator system. The distribution of Fe3O4 nanoparticles inside the composite latex particles was expected to be homogeneous. The nucleation and morphology of the composite latex particles were mainly controlled by the concentration of the surfactant, Span80, in cyclohexane. The properties of the composite latex were examined with several instruments such as DSC and TGA. Finally, the superparamagnetic and thermoresponsive characteristics of this functional composite latex were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3987–3996, 2006
Toughening of thermosets by the creation of residual compressive stresses
Authors: Kim Ho Sung , Kim Nam Ho 
Published: March 2006

AbstractThe toughening of thermosets through the creation of residual compressive stresses around microspheres was studied. Expandable, hollow microspheres containing gas with heating were used for the creation of residual compressive stresses. Microscopic compressive residual stresses in the vicinity of the crack tip were graphically analyzed and related to the macroscopic mechanical behavior for mode I fracture. The graphical analysis and experimental results confirmed that toughening was achieved mainly because of residual compressive stresses rather than a postcure effect. As expected, however, no toughening effect was found in mode III fracture. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4045–4051, 2006
Cellulose acetate reverse osmosis membranes: Optimization of the composition
Authors: Duarte A. P. , Cidade M. T. , Bordado J. C. 
Published: March 2006

AbstractMembranes based on cellulose acetate for reverse osmosis can possibly be applied to the so‐called salinity process of energy generation and water desalinization. The requirements for membranes for these two different applications are a relatively high water flux and low salt permeability. In this article, we present the optimization of the composition of such membranes. We started by producing membranes with a patented casting solution with the following composition: 45.77 wt % dioxane, 17.61 wt % acetone, and 8.45 wt % acetic acid (solvents); 14.09 wt % methanol (nonsolvent); and 7.04 wt % cellulose diacetate and 7.04 wt % cellulose triacetate. The membranes produced with this solution were analyzed comparatively, with the membranes obtained by the introduction of modifications to the following parameters: the solvent mix, the nonsolvent mix, the proportion of cellulose diacetate and cellulose triacetate in the casting solution, and the addition of reinforcing cellulose fibers. The results led us to conclude that the best membrane formulation had the following composition: 45.77 wt % dioxane, 17.61 wt % acetone, and 8.45 wt % acetic acid (solvents); 4.22 wt % cellulose triacetate and 9.86 wt % cellulose diacetate (polymers); 14.09 wt % methanol (nonsolvent); and 0.5 wt % cellulose fibers (with respect to the total polymer content). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4052–4058, 2006
Conductive epoxy/amine system containing polyaniline doped with dodecylbenzenesulfonic acid
Authors: Moreira Viviane X. , Garcia Filiberto G. , Soares Bluma G. 
Published: March 2006

AbstractWe developed a conductive epoxy/amine system containing polyaniline doped with dodecylbenzenesulfonic acid (PAni.DBSA). The curing behaviors of diglycidyl ether of bisphenol A with triethylenetetramine (TETA), PAni.DBSA, and both amine compounds at different concentrations were investigated by differential scanning calorimetry (DSC). Epoxy/TETA systems containing PAni.DBSA presented two distinct exothermic peaks at 90°C due to the cure by TETA as a hardener and at 236°C related to PAni.DBSA as the curing agent. The presence of PAni.DBSA in the systems constituted by epoxy/hardener in stoichiometric proportions resulted in a decrease in the glass‐transition temperature of the epoxy matrix, as indicated by DSC and dielectric analyses. Electrical conductivity was determined in the epoxy/amine networks, with the TETA concentration kept constant and also in stoichiometric proportions of mixed hardener (TETA + PAni.DBSA) to epoxy resin. The last condition resulted in a higher electrical conductivity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:4059–4065, 2006
Polyesterimide resins with built‐in polycyclic compounds
Authors: Wardzińska Elżbieta , Penczek Piotr 
Published: March 2006

AbstractPolyesterimide (PEI) resins are used for the preparation of PEI varnishes, for copper wire enameling. They are usually manufactured from dimethyl terephthalate (DMT), ethylene glycol, bisphenol A (BPA), tris(2‐hydroxyethyl) isocyanurate, trimellitic anhydride, and 4,4′‐diaminodiphenylmethane. The synthesis involves condensation and imidization. DMT and BPA were partially or completely replaced with the polycyclic components: dimethyl 2,6‐naphthalenedicarboxylate (NDC) and (R,S)‐1,1‐bis(4‐hydroxyphenyl)‐3,3,5‐trimethylcyclohexane (TMC), respectively, to enhance the heat resistance and the thermal stability. The effect of NDC and TMC on the solubility, the glass transition temperature, the course of the thermal decomposition, and the properties of magnet wires, enameled with the thus‐modified PEI varnishes, were investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4066–4073, 2006
Fe(2‐EHA)3/Al(i‐Bu)3/hydrogen phosphite catalyst for preparing syndiotactic 1,2‐polybutadiene
Authors: Lu Jun , Hu Yanming , Zhang Xuequan , Bi Jifu , Dong Weimin , Jiang Liansheng , Huang Baotong 
Published: March 2006

AbstractPolymerizing 1,3‐butadiene into syndiotactic 1,2‐polybutadiene with an iron(III) catalyst system has been investigated. Activity of the catalyst was affected by the type of cocatalyst alkylaluminum and the phosphorus compound as an electron donor, molar ratio of catalyst components, and their aging sequence and aging time of the catalyst. The microstructure and configuration of the polymer was decided by the catalyst components, the higher [Al]/[Fe] molar ratio tending to yield syndiotactic 1,2‐polybutadiene, while the higher [P]/[Fe] molar ratio favors the formation of amorphous 1,2‐polybutadiene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4265–4269, 2006
In vivo aging of gutta‐percha dental cone
Authors: Silva João Batista A. , de Paula Regina C. M. , Feitosa Judith P. A. , Gurgel‐Filho Eduardo Diogo , Maniglia‐Ferreira Claudio , de Souza Filho Francisco Jose 
Published: March 2006

AbstractGutta‐percha cone is the most widely used material for root canal filling. The in vivo aging of this cone focus on the degradation of its main organic component, trans‐1,4‐polyisoprene, was studied. Aged cones (25 samples) from 2 to 30 years of root canal filling were extracted from different patients in the occasion of retreatment by mechanical way. The information about the aging time was given by the patients. Gel‐permeation chromatography (GPC) and infrared spectroscopy (FTIR) were the analytical techniques used. Polyisoprene degrades with time of aging, but in a slow process. Decrease in polymer molar mass from 5.7 × 105 to 1.7 × 105 g/mol was observed in polyisoprene from cone after 30 years of root canal filling and inside a noninfected tooth. In tooth with caries and periodontal infection, the decrease in molar mass is higher (4.6 × 104 g/mol in cone with 10 years of aging). The production of carbonyl and hydroxyl groups in the aged material indicates that the process is oxidative, even in closed teeth. In these cases, the oxygen could be provided from tissue fluid. The degradation mechanism is complex and depends on many factors, besides time of root canal filling. The dental problem caused by the aging could be the production and migration of cytotoxic substances to periodontal ligament and the reduction on the canal sealing property due to the polymer weight loss. Both of them could contribute to the root canal treatment failure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:4082–4088, 2006
pH‐ and temperature‐sensitive microfiltration membranes from blends of poly(vinylidene fluoride)‐graft‐poly(4‐vinylpyridine) and poly(N‐isopropylacrylamide)
Authors: Zhai Guangqun 
Published: March 2006

AbstractThe copolymer poly(vinylidene fluoride)‐graft‐poly(4‐vinylpyridine) (PVDF‐g‐P4VP) was prepared through the graft copolymerization of poly(vinylidene fluoride) with 4‐vinylpyridine. Through the blending of the PVDF‐g‐P4VP copolymer with poly(N‐isopropylacrylamide) (PNIPAm) in an N‐methyl‐2‐pyrrolidone solution, PVDF‐g‐P4VP/PNIPAm membranes were fabricated by phase inversion in aqueous media. Elemental analyses indicated that the blend concentration of PNIPAm in the blend membranes increased with an increase in the blend ratio used in the casting solution. Scanning electron microscopy revealed that the membrane surface tended to corrugate at a low PNIPAm concentration and transformed into a smooth morphology at a high PNIPAm concentration. The surface morphology and pore size distribution of the microfiltration membranes could be regulated by the blend concentration of the casting solution, temperature, pH, and ionic strength of the coagulation bath. X‐ray photoelectron spectroscopy revealed a significant enrichment of PNIPAm on the membrane surface. The flux of aqueous solutions through the blend membranes exhibited a pH‐ and temperature‐dependent behavior. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4089–4097, 2006
Surface modification of natural substrates by atom transfer radical polymerization
Authors: Lindqvist Josefina , Malmström Eva 
Published: March 2006

AbstractSurface modification of various solid polysaccharide substrates was conducted by grafting methyl acrylate (MA) and styrene via atom transfer radical polymerization (ATRP) to produce well‐defined polymer grafts. The hydroxyl groups on the surfaces of the substrates were reacted with 2‐bromoisobutyryl bromide followed by graft copolymerization under ATRP conditions. The studied substrates were filter paper, microcrystalline cellulose, Lyocell fibers, dialysis tubing, and chitosan films. The modified substrates were analyzed by FT‐IR, water contact angle measurements, TGA, and SEM. FT‐IR characterization of the grafted substrates showed significant differences between the different substrates in the amount of grafted polymer. Higher amounts of polymer seem to be possible to graft from native cellulose substrates than from regenerated cellulose substrates. To investigate whether the grafted polymers were “living” after a longer time period, a second layer of polystyrene was grafted from a filter paper modified with PMA one year ago. FT‐IR characterization of the filter paper showed a peak corresponding to styrene, indicating that a block copolymer had been formed on the surface. Graft copolymerization can be used to change and tailor the surface properties of the polysaccharide substrates. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4155–4162, 2006
Synthesis and thermally responsive properties of novel Pluronic F87/polycaprolactone (PCL) block copolymers with short PCL blocks
Authors: Yuan Xiong Xiang , Chiu Tam Kam , Huat Gan Leong 
Published: March 2006

AbstractPolycaprolactone (PCL) was successfully grafted to both ends of Pluronic F87 block copolymers (PEO‐PPO‐PEO) to obtain novel amphiphilic PCL‐F87‐PCL block copolymers with short PCL blocks. The block composition and structure of PCL‐F87‐PCL block copolymers were studied by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetric (DSC), and wide angle X‐ray diffraction (WXRD) techniques. Several kinds of particles consisting of small micelles and medium and large aggregates were observed by laser light scattering (LLS) measurements because of the complicated structure of these copolymers. Importantly, PCL‐F87‐PCL block copolymers exhibit temperature‐sensitive behavior similar to that found in Pluronic systems. Compared with Pluronics, the critical micellization temperature (CMT) values of PCL‐F87‐PCL block copolymers obtained from surface tension measurements are significantly lower due to the enhanced hydrophobicity of PCL segments. A fully reversible sol–gel transition was detected for the PCL‐F87‐PCL hydrogels. Preliminary results show that there is no burst release for hydrophobic model drug, 9‐(methylaminomethyl) anthracene (MAMA), from PCL‐F87‐PCL hydrogel and the initial release rate is almost constant. This indicates that PCL‐F87‐PCL hydrogels possess attractive release profiles, which are beneficial for application in controlled release systems. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4163–4172, 2006