bluuebunny/crossref_metadata_2025_split huggingface dataset:
Membrane formation with presence of Lewis acid–base complexes in polymer solution
Authors: Pereira Cristina C. , Nobrega Ronaldo , Borges Cristiano P. 
Published: August 2002

AbstractThis work investigated membrane formation using Lewis acid–base complexes in a polymer solution, which consisted of poly(ether sulfone) (PES), Lewis acid–base complexes formed by N‐methyl‐2‐pyrrolidone (NMP, Lewis base), and dicarboxylic or monocarboxylic acids from a homologous series (Lewis acids). The solutions were characterized by viscosity measurements, IR spectroscopy, cloud point determination, and light transmission experiments. The membranes were characterized by scanning electron microscopy and gas permeation tests. The results indicated that the solvent–additive interaction, which is a function of their capacity to form complexes, and the acid chain length directly affect the viscosity and miscibility region. Consequently, these parameters combined with the complex dissociation influence the precipitation velocity of the polymer solutions, which will then affect the membrane transport properties. It is also pointed out that the membranes prepared by using 25 wt % PES at the same acid/NMP molar ratios and with different acids presented permeability coefficients in agreement with the binodal shift obtained in pseudoternary phase diagrams. Furthermore, when these solutions were exposed to the environment for a long period of time, the demixing onset sequence also agreed with the miscibility region for all solutions, except for the adipic acid solution because of its extremely high viscosity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2022–2034, 2002
Preparation of chitosan‐bound nitrobenzaldehyde metal complexes and studies on its catalytic oxidative activity and reactive mechanism
Authors: Chang Yue , Wang Yunpu , Su Zhixing 
Published: August 2002

AbstractChitosan‐bound nitrobenzaldehyde metal complexes (m‐CNBDM and o‐CNBDM, where M is Mn or Ni) were prepared and characterized by infrared, X‐ray photoelectron spectroscopy, solid‐state 13C‐NMR cross‐polarity/magic‐angle spinning, inductively coupled plasma, and elemental analysis. The complexes were found to be catalysts for the oxidation of hydrocarbons with molecular oxygen under mild conditions. o‐CNBDNi has a certain catalytic activity in the oxidation of n‐propylbenzene and isopropylbenzene and has no activity in the oxidation of ethylbenzene. Both o‐CNBDMn and m‐CNBDNi catalyze the oxidation of all the aforementioned hydrocarbons, whereas m‐CNBDMn has no catalytic activity. The main oxidative products of ethylbenzene and n‐propylbenzene are the same as α‐ol and α‐one, but they are 2‐benzyl‐isopropynol and isopropylbenzene peroxide for isopropylbenzene. A mechanism for the catalytic oxidative process is proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2188–2194, 2002
Acetal‐induced strength increases and lower resin content of MUF and other polycondensation adhesives
Authors: Pizzi A. , Beaujean M. , Zhao C. , Properzi M. , Huang Z. 
Published: August 2002

AbstractAcetals such as methylal and ethylal are shown to be particularly effective additives in improving the strength of wood boards bonded with melamine‐ urea‐formaldehyde (MUF) resins, although they show some appreciable but lesser effect on other resins too, particularly phenol‐ formaldehyde resins. They equally allow a considerable decrease in resin loading, and thus, in melamine content, on the bonded wood panel and at parity of performance. Their development as additives is then primarily, but not only, targeted at the MUF adhesive resins. One‐third decreases in MUF adhesives loading at parity of performance or equally internal bond (IB) strength increases approximately up to 50% by addition of methylal are shown to be possible by laboratory particleboard as well as by thermomechanical analysis (TMA). The reasons for methylal and ethylal behavior were studied by a variety of techniques, including liquid‐ and solid‐ phase 13C‐NMR and could be mostly ascribed to the increased effectiveness and participation of the melamine to resin crosslinking due to its now preferentially homogeneous rather than heterogeneous reactions, consequences of the increased solubility in water afforded by the acetal cosolvents. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2561–2571, 2002
Mercapto‐modified copolymers in elastomer blends. IV. The compatibilization of natural rubber/EPDM blends
Authors: Sirqueira Alex S. , Soares Bluma G. 
Published: August 2002

AbstractEthylene—propylene—diene functionalized with mercapto groups (EPDMSH) was employed as compatibilizing agent for natural rubber (NR)/EPDM blends, resulting in a substantial increase of the ultimate tensile strength of these blends without affecting the elongation at break. There is also a decrease of the curing time with the addition of as low as 2.5 phr of EPDMSH, mainly in NR/EPDM (70:30 wt %) blend, indicating the accelerator effect of this functionalized copolymer. This copolymer also increased the crosslink degree and the gel content. From dynamic mechanical analysis (DMTA), it was demonstrated that EPDMSH improves the covulcanization process. The reactive compatibilization of EPDMSH was demonstrated by the presence of insoluble material in nonvulcanized/compatibilized blends and by its thermogravimetric (TGA) analysis. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2892–2900, 2002; DOI 10.1002/app.10283
High solids content emulsions. III. Synthesis of concentrated latices by classic emulsion polymerization
Authors: Schneider M. , Graillat C. , Guyot A. , McKenna T. F. 
Published: August 2002

AbstractTwo different methods of producing bi‐ and trimodal latices of a mixture of methyl methacrylate, butyl acrylate, and small amounts of acrylic acid were tested. It is shown that a combination of concentrating blends of seed particles by semibatch reaction, followed by a nucleation of small particles plus a second semibatch phase allowed us to obtain stable latices with solids contents over 65% and viscosities of below 2500 mPa s−1 with little coagulum formation. The key parameter in determining latex stability, coagulum formation, and viscosity appears to be the the particle size distribution, and especially its modification attributed to secondary nucleation. Because it is not possible to eliminate water‐soluble monomers from the polymerization recipe, secondary (homogeneous) nucleation must be minimized by careful addition of the free‐radical initiator and choice of monomer feed flow rates. The nucleation of the third population in the trimodal latices is best accomplished with a mixed surfactant system because renucleation by anionic surfactant alone leads to detrimental changes in the particle size distribution (PSD) resulting from excessive flocculation of particles. In addition, it was found that the viscosity of the final products was not sensitive to small changes in the ionic strength of the latex, although neutralization to a pH of 6 effectively doubles the final latex viscosity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1916–1934, 2002; DOI 10.1002/app.10513
Viscoelastic behavior of AN‐g‐casein copolymer concentrated solution of sodium thiocyanate
Authors: Dong Qingzhi , Gu Lixia 
Published: August 2002

AbstractThe viscoelastic behavior of sodium thiocyanate concentrated solution of graft copolymer of acrylonitrile onto casein (AN‐g‐casein) was investigated in detail by nitrogen pressure capillary rheometer. The experimental results show that the concentrated solution of AN‐g‐casein is a non‐Newtonian fluid of shear thinning. The end correction increases with the increase of shear rate. In the course of practical spinning, the real shear stress only attributes about 35% to the apparent shear stress, which confirms the essentiality of end correction for the capillary extrusion of the concentrated solution of the graft copolymer. By using the Dewitt model, the Couette correction ξ and recoverable shear strain SR were analyzed and separated. Quantitative function relation of ξ and SR versus shear rate and temperature were deduced. It is a common equation within the range of experiment. In practical spinning process, the real viscoelastic parameters can be easily predicted by only a piece of flowing curve based on the common equation. Real elastic model G under any shear rate in the range of experiment was calculated. It was found that G increases with an increase of shear rate, which is opposite to the conclusion reported by Hayahara. The main reason for the error may be that Hayahara used the same Couette correction at a higher shear rate. Further, the die swell in the spinning process can be estimated efficiently. The theoretical base for the stability of AN‐g‐casein spinning technology was provided. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1721–1728, 2002; DOI 10.1002/app.10554
Reactive reinforcement of the interface of poly(ether sulfone)/poly(phenylene sulfide) polymer blend by PMR–POI
Authors: Lai Mingfang , Yang Yuming , Liu Jingjiang 
Published: August 2002

AbstractThe effect of polymerization of monomer reactant–polyimide (POI) as the interfacial agent on the interface characteristics, morphology features, and crystallization of poly(ether sulfone)/poly(phenylene sulfide) (PES/PPS) blends were investigated using a scanning electron microscope, FTIR, WAXD, and XPS surface analysis. It was found that the interfacial adhesion was enhanced, the particle size of the dispersed phase was reduced, and the miscibility between PES and PPS was improved by the addition of POI. It was also found that POI was an effective nucleation agent of the crystallization for PPS. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1297–1306, 2002
Preparation and properties of branched polybutylenesuccinate
Authors: Kim Eun Kyoung , Bae Jong Seok , Im Seung Soon , Kim Byoung Chul , Han Yang Kyoo 
Published: August 2002

AbstractTo obtain long branched polybutylene succinate (PBS), modified PBSs were prepared by introducing a branching agent, trimethylol propane (TMP), to the polycondensation system of succinic acid and 1,4‐butanediol. Molecular parameters such as absolute molecular weight and root‐mean‐square (RMS) radius of the modified PBSs were measured by gel permeation chromatography (GPC) with a multiangle laser light‐scattering (MALLS) detector. The RMS radius of TMP05, PBS prepared by incorporating 0.5 wt % TMP during polycondensation, was the smallest of all PBSs tested at the same molecular weight. The notable shear thinning and much reduced loss tangent for TMP05 qualitatively supported the difference in their molecular structures predicted by GPC. The analytical results indicated that introducing 0.5 wt % TMP produced PBS with chain branches long enough to produce molecular entanglements. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1388–1394, 2001
Ammonium perchlorate–binding poly(allylamine hydrochloride) hydrogels for wastewater remediation
Authors: Kioussis Dimitri R. , Smith Daniel F. , Kofinas Peter 
Published: August 2002

AbstractSystems that are capable of removing highly toxic anions from wastewater effluents, even at extremely low concentrations, are a major need in the defense industry. This study reports on the features of two new batch and continuous‐flow sorption processes with regard to ultimate removal and recovery of the perchlorate (ClO) anion from ammonium perchlorate (NH4ClO4) wastewater. The sorbent developed is a crosslinked poly(allylamine hydrochloride) (PAA·HCl) polymeric hydrogel. The pH‐sensitive PAA·HCl hydrogels were synthesized by chemically crosslinking a solution of linear PAA·HCl chains with epichlorohydrin (EPI). The perchlorate‐binding capacity of the polymer gels was measured in standard solutions and studied as a function of gel synthesis parameters. Equilibrium perchlorate loadings of 5770 ± 870 mg ClO/g gel were calculated from measurement of the decrease in perchlorate concentration in aqueous standard solutions using UV‐Vis spectrophotometry. Batch experiments in wastewater originating from the Naval Surface Warfare Center (NSWC) Indian Head Division showed that perchlorate concentrations decreased by 85%. Preliminary lab‐scale packed‐column experiments in wastewater achieved up to 40% reduction in total perchlorate content. The regeneration ability of the gels was demonstrated by release of the bound perchlorate anions, upon washing with a 1N NaOH solution, providing opportunities to recover and reuse the hydrogel over multiple regeneration cycles. The PAA·HCl hydrogels are demonstrated to be appropriate materials for treating wastewaters that contain ammonium perchlorate. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2073–2083, 2001
Porous biodegradable polyesters. II. Physical properties, morphology, and enzymatic and alkaline hydrolysis of porous poly(ϵ‐caprolactone) films
Authors: Tsuji Hideto , Ishizaka Takeharu 
Published: August 2002

AbstractPorous poly(ϵ‐caprolactone) (PCL) films were prepared by water extraction of poly(ethylene oxide) (PEO) from their solution‐cast phase‐separated blend films and the dependence of their blend ratio [XPCL = PCL/(PEO + PCL)] and molecular weight of PEO on the porosity, pore size, crystallinity, crystalline thickness, mechanical properties, morphology, and enzymatic and alkaline hydrolysis of the porous PCL films were investigated. The film porosity or extracted weight ratio was in good agreement with the expected values, irrespective of XPCL and molecular weight of PEO. The maximum pore size was larger for the porous films prepared using PEO having a lower molecular weight, compared with films prepared using PEO having a higher molecular weight at the same XPCL. Differential scanning calorimetry of the porous PCL films revealed that their crystallinity and crystalline thickness were almost constant, regardless of XPCL and molecular weight of PEO. The Young's modulus and tensile strength of the porous films decreased, whereas the elongation‐at‐break increased with decreasing XPCL. The enzymatic and alkaline hydrolysis rates of the porous films increased with a decrease in XPCL and an increase in the molecular weight of PEO. The porous PCL films having Young's modulus in the range of 2–24 kg/mm2 and enzymatic hydrolysis rate in the range of one‐ to 20‐fold that of the nonporous PCL film could be prepared by altering XPCL and the molecular weight of PEO. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2281–2291, 2001
Palladium sorption on glutaraldehyde‐crosslinked chitosan in fixed‐bed systems
Authors: Ruiz Montserrat , Sastre Ana Maria , Zikan Maria Celia , Guibal Eric 
Published: August 2002

AbstractPalladium sorption on glutaraldehyde‐crosslinked chitosan was studied in fixed‐bed column systems. Sorption performances were controlled mainly by the presence of competitor anions in the solution: The presence of sulfate, chloride, or nitrate (to a lesser extent) significantly decrease sorption properties. Although the influence of other operating conditions such as particle size, column depth, and flow velocity on sorption breakthrough cannot be completely neglected, palladium sorption is less significantly controlled by these parameters than for the sorption of other metal ions, owing to fast mass transfer and weak intraparticle diffusion control. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 153–165, 2001
Mechanical properties and ionic conductivity of gel polymer electrolyte based on poly(vinylidene‐fluoride‐co‐hexafluoropropylene)
Authors: Kim Seong Hun , Choi Jong Kuk , Bae Young Chan 
Published: August 2002

AbstractGel polymer electrolytes were prepared from poly(vinylidene‐fluoride‐co‐hexafluoropropylene) (PVH), which had higher mechanical properties and a higher dielectric constant (ϵ = 8–13) than other polymeric matrixes. The mechanical properties and ionic conductivities were investigated as a function of the blend ratio of the electrolyte solution and polymer matrix. Ethylene carbonate/γ‐butyrolactone and lithium triflate were used as the solvent and salt, respectively. The mechanical properties such as the tensile strength, tensile modulus, compression modulus, and dynamic shear modulus were evaluated. The highest ionic conductivity was 1.09 × 10−3 S/cm at 25°C for 40 wt % PVH against the electrolyte solution. The tensile strength, tensile modulus, and compression modulus were increased with increasing PVH content and they all abruptly changed between 70 and 80 wt % PVH. The dynamic shear moduli showed behavior typical of a gel and varied with the shear strain amplitude or applied frequencies. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 948–956, 2001
Microstructural changes of phenolic resin during pyrolysis
Authors: Ko Tse‐Hao , Kuo Wen‐Shyong , Chang Ying‐Huang 
Published: August 2002

AbstractAfter curing, phenol‐formaldehyde resins were postcured at 230°C in air for 32 h and then carbonized and graphitized from 300 to 2400°C. Thermal fragmentation and condensation of the polymer structure occurred above 300°C. The crystal size of the cured phenolic resins decreased with the temperature increase. Above 600°C the original resin structures disappeared completely. Below 1000°C the stack size (Lc) and crystal size (La) were small. Above 1000°C the Lc increased with the increasing treatment temperature. The carbonized and graphitized resins were characterized using Raman spectroscopy. Below 400°C there were no carbon structures in the Raman spectra analysis. Above 500°C the G and D bands appeared. The frequency of the G band of all carbonized and graphitized samples shifted to 1600 cm−1 from the 1582 cm−1 of graphite. The D band shifted to 1330 cm−1 from the 1357 cm−1 of the imperfect carbon. The carbonized and graphitized phenolic resins could not be considered as truly glassy or amorphous carbon materials because they had some degree of order in the basal plane. However, the crystal size was very small even at 2400°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1084–1089, 2001
Large deformation mechanical behavior of gelatin–maltodextrin composite gels
Authors: Normand Valery , Plucknett Kevin P. , Pomfret Stephen J. , Ferdinando Dudley , Norton Ian T. 
Published: August 2002

AbstractThe large deformation failure behavior of gelatin–maltodextrin composite gels was assessed. All the studied compositions were selected to lie within the incompatibility domain of the gelatin–maltodextrin phase diagram at 60°C, which produced gelatin continuous (maltodextrin included) and maltodextrin continuous (gelatin included) composites. Composite microstructural evaluation was performed using confocal laser scanning microscopy (CLSM). The large deformation mechanical behavior was measured in tension and compression experiments. Crack–microstructure interactions were investigated by dynamic experiments on the CLSM. The gelatin continuous composites exhibited pseudo‐yielding behavior during tension and compression testing, and there was a significant decrease in modulus that arose from interfacial debonding. Conversely, the maltodextrin continuous composites exhibited an essentially brittle failure behavior, and there was an approximately linear increase in stress with increasing strain until fracture (which occurred at significantly lower strains than for the gelatin continuous composites). The CLSM observation of the failure of the notched samples also demonstrated interfacial debonding in the crack path; however, this occurred at significantly smaller strains than for the gelatin continuous samples with minimal elastic–plastic deformation of the maltodextrin matrix. The Poisson ratio was estimated to be close to 0.5 for these composites for all examined compositions. Compositions corresponding to a tie line of the phase diagram were also investigated to assess the influence of the relative phase volume (for constant phase compositions) on the failure behavior. The majority of the parameters subsequently extracted from the stress–strain curves were apparently functions of the individual phase volumes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 124–135, 2001
Assessment of efficacy of trivalent lanthanum complex as surface modifier of calcium carbonate
Authors: Feng Jiachun , Chen Mingcai , Huang Zhitang 
Published: August 2002

AbstractA complex of trivalent lanthanum stearate with stearin (REC) was used as a surface modifier to treat calcium carbonate, and its efficacy was assessed. The measurement of the viscosity of a CaCO3/liquid paraffin suspension demonstrated that REC treatment could considerably improve the dispersion of filler in nonpolar media. The FTIR spectrum analysis revealed that the REC bonded to the CaCO3 surface not only by physical absorption but also by a chemical reaction. The REC could change the surface properties of CaCO3, resulting in greater hydrophobicity of the surface and enhanced compatibility with nonpolar matrices. The mechanical properties and melt flow rate (MFR) examination of polypropylene (PP)/CaCO3 composites showed that REC treatment remarkably enhanced the toughness and MFR of composites at higher filler loading. The fractured surface observation with SEM showed improved filler dispersion and enhanced interfacial adhesion between the filler and matrix in PP composites filled with REC‐treated CaCO3. All these improvements demonstrated that REC is an effective surface modifier of CaCO3. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1339–1345, 2001
An analysis of the correlation between structural anisotropy and dimensional stability for drawn poly(lactic acid) films
Authors: Smith Patrick B. , Leugers Anne , Kang Shuhui , Hsu Shaw Ling , Yang Xiaozhen 
Published: August 2002

AbstractThe anisotropic structures found in drawn poly(lactic acid) films are strongly correlated to their overall dimensional stability. Several aspects of this relationship can be efficiently characterized by Raman spectroscopy. We determined the degree of orientation in these drawn films by measuring the relative intensity of the polarized and depolarized components and the shift in the relative band positions. The bandwidth and specific band frequency also correlated well with the degree of sample crystallinity. These aspects make the Raman method amenable for the online monitoring of orientation and crystallinity in commercial processes. A molecular understanding of heat setting to reduce film shrinkage is also proposed. Raman data from films that were heat‐set while physically constrained suggest that amorphous‐phase relaxation does not occur during heat setting. Rather, the level of crystallinity increases substantially, indicating that the cause of low shrinkage in the films was due to crystalline network formation rather than amorphous‐phase relaxation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2497–2505, 2001