bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of surface modified polytetrafluoroethylene on polyacetal/polytetrafluoroethylene blends
Authors: Chiang Wen‐Yen , Huang Chi‐Yuan 
Published: April 2003

AbstractFive kinds of blends: polyacetal (POM) and polytetrafluoroethylenes (PTFEs) [pure (PTFE), coupling agent coated (LZ‐PTFE), chemical‐treated (CPTFE, containing NaF salt), chemical‐treated (WPTFE, no NaF salt), coupling agent coated WPTFE(LZ‐WPTFE)] were prepared by mechanical blending. The PTFE presented in the blends, had good wear resistance properties. However, the adhesion interaction between the POM and the PTFE was poor, and increasing the PTFE content caused a decrease in the mechanical properties. Using the chemical surface treatment method to etch PTFE could cause treated‐PTFE to homogeneously disperse in POM. This result caused the POM/treated‐PTFE blends to have higher mechanical properties than those of the POM/PTFE blends. The NaF salt that adsorbed on the CPTFE surface acted as a coupling agent and offered a very strong adhesion interaction between the POM and the CPTFE. The free salt also acted as a nuclei to aid POM in crystallizing. As a result, the POM/CPTFE blends possessed the highest mechanical properties of all the blends and the best wear resistance property of POM/modified‐PTFE(LZ‐PTFE, LZ‐WPTFE, WPTFE, CPTFE) blends. © 1993 John Wiley & Sons, Inc.
Characterization of oligomers from 1,4‐butanediol and toluene diisocyanate
Authors: Lesar Meta , Z̆igon Majda , Malavas̆ic̆ Tatjana 
Published: April 2003

AbstractPolyurethane oligomers from 1,4‐butanediol (BD) and toluene diisocyanate (TDI) with a various excess of BD were synthesized. Their molar masses were measured by gel permeation chromatography and the molar mass distribution correlated with the statistic theory. 1H‐, 13C‐, 1H–1H‐COSY–, ATP–, and 15N‐NMR spectra of reaction products were recorded, and from the ratio of proton integrals of characteristic terminal and inner urethane groups, the reactivity ratio of the para and ortho NCO groups in 2,4‐TDI was calculated to be approximately 1.8 at a lower excess of BD. 15N‐NMR spectroscopy was found not to be selective enough to detect small amounts of side reactions. © 1993 John Wiley & Sons, Inc.
Unified modeling technique for high‐viscosity, melt‐phase, condensation polymer reactors
Authors: Sampson Kendree J. , Neogi Swati , Medlin James C. 
Published: April 2003

AbstractMathematical models for chemical reaction and mass transfer occurring in the manufacture of high‐viscosity condensation polymers are considered. A preliminary study indicates that several diverse models can be represented using a single formula based upon an effectiveness factor. The effectiveness factor is shown to depend upon a ratio of time scales of mixing and reaction. The formula giving the effectiveness factor in terms of the time scales ratio is shown to depend upon mixing assumptions only. Starting with a mixing‐cell model, a new modeling framework is developed and shown to include the previous models as special cases. The framework is free of inherent mixing assumptions and can be applied to a wide variety of situations once the mixing characteristics are specified. © 1993 John Wiley & Sons, Inc.
Electrosynthesis of conducting poly(p‐phenylene)
Authors: Bhadani Suraj N. , Gupta Sumanta K. Sen , Gupta Manoj K. , Prasad Jagdeo 
Published: April 2003

AbstractThe polymerization of benzene was studied in bulk and in nitrobenzene using BF3O (C2H5)2 as a supporting electrolyte at platinum electrodes to obtain poly(p‐phenylene). The polymers were formed as a black thready mass on the anode and their yields were restricted to the area of the anode in the electrochemical cell. The yields of the polymers formed in the bulk and in nitrobenzene were almost equal, although electrical resistances of the polymers obtained from the bulk were relatively lower. Cyclic voltammetry measurements suggest that the polymerization of benzene took place from the species generated anodically in situ. © 1993 John Wiley & Sons, Inc.
Nonlinear optical properties of solution of the substituted polyaniline
Authors: Wan Meixiang , Yang Jiping , Jiang Qian , Mi Xin , Ye Peixian 
Published: April 2003

AbstractNonlinear optical properties of solution of substituted polyaniline (PANI), such as polytoluidine (POT), Br–POT, and Br–PANI, were measured by the degenerate four‐wave mixing (DFWM) method as a function of the concentration of solution and the protonation state. The observed nonlinear optical properties are intrinsic and might be related to the resonance effect and the photoexcitation of the molecule on the quinoid ring of the polyemeraldine chain. © 1993 John Wiley & Sons, Inc.
Properties of cation‐exchange membranes prepared by radiation grafting of acrylic acid onto tetrafluoroethylene–ethylene copolymers
Authors: Kostov G. K. , Atanassov A. N. 
Published: April 2003

AbstractSome properties of the ion‐exchange membranes prepared by simultaneous and preirradiation techniques of grafting of acrylic acid onto tetrafluoroethylene–ethylene copolymer films, including porous microfilters, have been studied. The water content, electric resistance, transport number, distribution of grafting, thermal and chemical stability, and mechanical characteristics of the membranes were determined as a function of the grafting degree. Graft polymerization proceeds from both surfaces of the polymer film into the polymeric matrix depth. Cation‐exchange membranes prepared possess good electrochemical and mechanical properties, high thermal and chemical stability at grafting degrees from 30 to 50%, and can be successfully used in electrodialysis processes. © 1993 John Wiley & Sons, Inc.
Functional polymers for colloidal applications. VII. Aggregate formation of lipophile‐modified polyacrylates in aqueous solutions
Authors: Kuo Ping‐Lin , Hung Min‐Nan , Lin Yueh‐Hsien 
Published: April 2003

AbstractWater‐soluble copolymers, poly(dodecyl acrylate–coacrylic acid) (PDA), are synthesized by copolymerizing different ratios of dodecyl–acrylate/acrylic acid. Their aqueous solutions are transparent. The plots of I1/I3 (the intensity ratio of pyrene emission at 374 nm and 385 nm) and of surface tension as a function of polymer concentrations are combined to verify the existence of the aggregates of PDAs. It is found that the aggregations begin to form at concentrations below that of the polymer transfer to the air–water interface. The plots of I1/I3 as a function of polymer concentration shows that the polymers with a higher ratio of dodecyl acrylate form polymer aggregates at lower concentrations. The hydrophobicity of the inner core of polymer aggregates is close to that of sodium dodecyl sulfate (SDS). Polymer solutions of PDA 30, PDA 30L, and PDA 15, show significant solubilization ability to pyrene. (The molar ratio of dodecyl acrylate/total acrylates is 30%, 30%, and 15% for PDA 30, PDA 30L, and PDA 15, respectively. L, low molecular weight.) The solubilization ability increases with the increase in polymer concentration and degree of substitution of dodecylamine. The intensity ratio of the excimer emission to monomer emission of pyrene (Ie/Im) increases with increasing polymer concentration, roughly parallel to the increase in the amount of pyrene solubilized. However, the Ie/Im at a fixed pyrene concentration (Ie/I) decreases with increasing polymer concentration. These phenomena are interpreted in terms of the amount of pyrene solubilized and the size and concentration of the polymer aggregates. © 1993 John Wiley & Sons, Inc.
Thin films from 96% quinoline
Authors: Honeychuck R. V. , Cozzens R. F. , Shirk J. S. , Lindle J. R. 
Published: April 2003

AbstractFilms from 96% quinoline and from 96% quinoline with poly(1,4‐cyclohexylene carbonate), mesoporphyrin IX dimethyl ester, and Pd(II)mesoporphyrin IX dimethyl ester have been cast via heating and subsequent evaporation. The films are approximately 3 μm thick, with a maximum variation normal to the surface of 0.10 μm in 2 mm of surface travel. The optical quality of the samples formed from 96% quinoline alone is excellent and variable from the 96% quinoline/solute combinations. The third‐order nonlinear optical (NLO) properties of these materials have been examined. © 1993 John Wiley & Sons, Inc.
Pervaporation of ethanol—water mixture by Co60 γ‐ray irradiation‐modified nylon 4 membrane
Authors: Lai Juin‐Yih , Chen Rong‐Yuh , Lee Kueir Rarn 
Published: April 2003

AbstractThe ethanol—water separation by pervaporation with γ‐ray irradiation‐modified nylon 4 membrane was investigated. The membrane was prepared by homografting γ‐ray irradiation of vinyl acetate (VAc) monomer onto nylon 4, poly(vinyl acetate) (PVAc)‐homo‐g‐nylon 4 followed by hydrolysis treatment, poly(vinyl alcohol) (PVA)‐homo‐g‐nylon 4. The homografting method shows significant improvement in the degree of grafting of (VAc) onto nylon 4 over the heterografting method. For example, the degree of grafting of the VAc with 30 vol % and total dose of 2 Mrad for the heterografted method and for the homografted method are 14.1 and 42.2%, respectively. The effects of irradiation with or without oxygen in solution, irradiation time, VAc content, degree of grafting, crystallinity, feed concentration, and operating temperature on performances of the PVA‐homo‐g‐nylon 4 membrane were carried out. Comparison of the separation factor of sorption in membrane (αsorp) and that of pervaporation (αperv) was made. A separation factor of 7.3 and a 0.691 kg/m2 h permeation rate can be obtained by the PVA‐homo‐g‐nylon 4 membrane with a degree of grafting of 42.2% for 90 wt % ethanol feed concentration. Compared with the unmodified nylon 4 membrane, which has the separation factor of 4 and permeation rate of 0.350 kg/m2 h, the PVA‐homo‐g‐nylon 4 membrane shows improved a separation factor and permeation rate. © 1993 John Wiley & Sons, Inc.
Phase behavior of mixtures of tetrabromobisphenol‐A polycarbonate in solvents and nonsolvents
Authors: Beck H. N. 
Published: April 2003

AbstractThe relative solubility and phase relationships are presented for ternary mixtures consisting of the polymer tetrabromobisphenol‐A polycarbonate in three representative good solvents and nine nonsolvents. The effects of temperature, composition, compound structure, compound molecular weight, and hydroxyl concentration upon the relative solvent power of the liquid mixtures and thus upon the phase borders separating one phase from multiphase compositions are discussed. The importance of such information for the preparation of permselective membranes is emphasized. © 1993 John Wiley & Sons, Inc.
Gas permeabilities of poly(trimethylsilylpropyne) membranes surface modified with CF4 plasma
Authors: Lin Xiao , Xiao Jun , Yu Yali , Chen Jie , Zheng Guodong , Xu Jiping 
Published: April 2003

AbstractSurface fluorination of poly(trimethylsilylpropyne) (PTMSP) membranes by CF4 plasma was studied. The surface fluorination of the membranes was carried out in an atmosphere of CF4 in a capacitively coupled discharge apparatus with external electrodes. Dramatic increase in selectivity (P/P) was observed. The effect of fluorination conditions such as duration of treatment and discharge power on the permeabilities of the membranes was studied. X‐ray photoelectron spectrometric data of modified PTMSP membranes showed a drastic alternation in the surface layer. The P and P/P of the membranes were observed to be dependent on the F/C atomic ratio. At F/C > 1, the P/P value of the membranes could be more than four. © 1993 John Wiley & Sons, Inc.
Radiation‐induced sol‐gel transition of protein: Effects of radiation on diffraction property
Authors: Nisizawa Mizuho 
Published: April 2003

AbstractSolid gelatin was irradiated with 60Co gamma rays, and the effects of radiation on the diffraction property of the protein molecule were studied by measuring the X‐ray diffraction intensity at different radiation doses and elapsed times after irradiation. The effects of radiation on the ordered conformation of the protein molecule were discussed. © 1993 John Wiley & Sons, Inc.
Single‐ion conduction and lithium battery application for ionomeric cross‐linking polymer
Authors: Zhang Sheng Shui , Wan Guo Xiang 
Published: April 2003

AbstractThe single‐Li+ conduction of the cross‐linking poly [oligo (oxyethylene) methacrylate‐co‐lithium methacryloyl hexylsulfonate]s was studied, and an Li+ ionic transport number of 0.994 estimated from the isothermal transient ionic current (ITIC), in which an ion‐blocking platinum electrode was used. The results show that Li+ ‐ionic conduction can be reasonably described by Vogel–Tammann–Fulcher (VTF) equation, suggesting that there is close correlation between ionic migration and segmental motion in these polymers. The battery composed of lithium/this copolymer film/polyaniline supplied a constant short circuit current (JSC) of 45 μA/cm2 and an open circuit potential (VOC) of 3.6 V at 25°C. © 1993 John Wiley & Sons, Inc.
Influence of curative, filler, compatibilizer, domain size, and blend ratio on the dynamic mechanical properties of silicone–EPDM blends
Authors: Kole Swapan , Bhattacharya Ashis , Tripathy D. K. , Bhowmick Anil K. 
Published: April 2003

AbstractDynamic property measurements show two loss tangent peaks for silicone rubber at about −95°C and −20°C, and one peak for EPDM at about −30°C. DSC studies confirm that the first loss tangent peak of silicone rubber is caused by its glass transition and the other is caused by crystalline melting of silicone. Measurements with blends reveal the individual characters of the components in the blends. Large differences in the solubility parameter between them also explains the incompatible nature. The effects of curative, blend ratio, and ageing are found on the glass‐transition temperature and also on the storage modulus and loss tangent. Although filler does not change the glass‐transition temperature, it changes the dynamic properties. Silane‐grafted EPR shows an optimum concentration as a compatibiliser, resulting in improved mechanical properties of the blends. The domain size of the blends also reduces with the introduction of the compatibilizer. Imposition of restriction on the domains by partial curing during mixing results in materials with higher storage modulus. The morphology study indicates an interpenetrating network structure for these restricted domain blends. © 1993 John Wiley & Sons, Inc.
Viscosity, yield stress, slip, and natural convection of HSPAN gel–water dispersions
Authors: Hardin Richard A. , Burmeister Louis C. 
Published: April 2003

AbstractThree hydrolyzed‐starch–polyacrylonitrile (HSPAN) copolymer materials tested as gel–water dispersions in a Brookfield rotating spindle viscometer exhibited velocity slip at solid boundaries and a yield stress. Dispersions with 0.5% HSPAN concentrations were about 20,000 times more viscous than water when the shear stress surpassed the yield stress and viscous power‐law flow ensued. The apparent viscosity of an HSPAN gel–water dispersion was reduced by nearly an order of magnitude when tap water was substituted for deionized water. The apparent viscosity of the HSPAN gel–water dispersions decreased by about 30% after the fluid was continuously maintained at a temperature of 80°C for 1 week, and by an order of magnitude or more after 3 weeks under those conditions. In natural convection tests, the yield stress enabled an HSPAN gel–water dispersion to withstand greater temperature differences across a horizontal layer before inception of natural convection than a fluid without one. © 1993 John Wiley & Sons, Inc.
Polymerization of methyl methacrylate in 3‐component cationic microemulsion
Authors: Rodriguez‐Guadarrama L. A. , Mendizabal E. , Puig J. E. , Kaler E. W. 
Published: April 2003

AbstractMethyl methacrylate has been polymerized in three‐component o/w microemulsions made with the cationic surfactant dodecyltrimethylammonium bromide (DTAB). The effects of temperature type and concentration of initiator (AIBN or potassium persulfate), and surfactant and monomer concentration on polymerization kinetics are investigated. Final conversions and reaction rates increase with increasing monomer and initiator concentrations and with higher reaction temperatures. The rate of polymerization shows initiation and termination intervals, but no constant rate interval is observed. Both molecular weight and particle size decrease as the concentration of initiator increases, regardless of type of initiator. Latexes with small particle size (< 70 nm) and high molecular weights (>106) were obtained in all cases. Activation energies for the microemulsion polymerization of MMA with AIBN (10.3 kcal/mol) and KPS (13.4 kcal/mol) are smaller than that of bulk polymerization using AIBN (20 kcal/mol). © 1993 John Wiley & Sons, Inc.
Elastic properties of random‐linked cis‐PB networks: A characterization and gel point study
Authors: Pyckhout‐Hintzen W. , Müller B. , Springer T. 
Published: April 2003

Abstractcis‐Polybutadiene networks with microstructure 98% cis, cross‐linked in the bulk state by gamma irradiation, were characterized in terms of their mechanical properties. Data from stress‐strain analyses, swelling degrees, stress relaxation, and random‐linking theory are in accordance and the estimated gel points practically coincide. Trapped entanglements lead to a 30% increase in the network modulus, from which also the plateau modulus, 0.71 ± 0.09 MPa, was determined. The tensile data were obtained from Mooney‐Rivlin representations without junction constrained corrections. Preliminary stress‐relaxation experiments indicated a slow relaxation at room temperature. It can be concluded that the assumption of additive contributions from chemical and entanglement cross‐link densities in the Langley theory works well in the range of doses investigated here. © 1993 John Wiley & Sons, Inc.
Functionalization of polyester PET fibers
Authors: Arroyo Miguel , Tejera María , Ibarra Luis 
Published: April 2003

AbstractIn order to promote chemical linkage between polyester PET fibers and thermoplastic or elastomer matrices, a diazide derivative has been synthetized and reacted with the free hydroxyl groups of the fibers. The completion of the reaction was controlled by means of IR spectroscopy and chemical analysis, and fiber characterization was carried out by thermogravimetric and DSC techniques. The obtained results permit the determination of the suitability of the synthetized diazide to functionalize PET fibers that could be used as reinforcing fibers for polymer matrices composites. © 1993 John Wiley & Sons, Inc.
New poly(bisbenzoylamine imide) series: Synthesis and characterization
Authors: Litauszki L. , Karasz F. E. 
Published: April 2003

AbstractThree new series of poly(bisbenzoylamine imide)s, incorporating different aromatic diamines, have been synthesized. The polymers, obtained by the two‐step procedure, have been characterized by DSC, TGA, X‐ray, FTIR, and 1H‐NMR methods. Thermal analysis showed glass transition temperatures in the range of 200°–250°C and decomposition at 430°–495°C. Most DSC runs displayed an exothermic event above Tg that was due to cold crystallization of the polymer molecules. A melting point was not observed. The new polymers, even before annealing, showed sharp X‐ray diffraction patterns, evidence of semicrystallinity. The polymers, soluble in polar solvents, were analyzed by NMR in solution. Typical chemical shifts for the bisbenzoylamine protons were reported; FTIR spectra showed the characteristic imide peaks. Due to a near overlap of the carbonyl vibration of the imide group with the bisbenzoylamine carbonyl, the latter vibration was detected in only one series. © 1993 John Wiley & Sons, Inc.
Crystallization kinetics of poly(ethylene terephthalate) in compositions containing naturally functionalized triglyceride oil
Authors: Barrett L. W. , Sperling L. H. , Gilmer J. , Mylonakis S. G. 
Published: April 2003

AbstractThe crystallization of poly(ethylene terephthalate) (PET) in blends with naturally functionalized triglyceride oils and their networks has been investigated. Crystallization kinetics of PET in the presence of small amounts of castor oil is improved, both in cooling from the melt state, and in heating from the glassy state. In conjunction with the nucleating agent sodium benzoate, either chemically bonded to castor oil or as a simple mixture, even greater enhancements of crystallization are observed. The PET crystallinity in semi‐IPNs and blends of low to intermediate castor oil‐HMDI polyurethane content are higher than that of neat PET (on a per gram of PET basis). Crystallinity in compositions with a high triglyceride oil network content is greatly affected by the presence of the network, with large melting point depressions, and loss in overall crystallinity. In cases where the triglyceride oil network is completely formed in a miscible melt with PET, the PET is unable to crystallize on cooling, resulting in amorphous semi‐IPNs. Plasticization due to the oil, nucleation from added agents, bond interchange reactions between the oil and the PET, overall chemical composition, and the presence of a triglyceride oil network are found to have a controlling influence over the type and extent of PET crystallinity in the compositions. © 1993 John Wiley & Sons, Inc.
Characterization of nonideal networks by stress‐strain measurements at large extensions
Authors: Klüppel M. 
Published: April 2003

AbstractIt is shown how a characterization of unfilled, amorphous rubber networks can be evaluated from uniaxial stress‐strain measurement data. Beside the cross‐linking density, the relative scission probability during the curing procedure is evaluated, which determines the amount of dangling free chain ends and the number of trapped entanglements. These values are found from the C2 term of the Mooney‐Rivlin equation by using the predictions of a tube model. A necessary requirement for applying stress‐strain measurements at large extensions is the consideration of the finite extensibility component of the reduced stress. It is taken into account by using a numerical procedure, which derives from a series expansion of the inverse Langevin approximation. The experimental results found at natural rubber networks cross‐linked with thiuram (TMTD) and peroxid (DCP) show that network defects cannot be neglected in the DCP networks. They are assumed to be connected to the worse tensil strength properties compared to the TMTD networks. © 1993 John Wiley & Sons, Inc.
Orientation gradients at polymer surfaces. I. Description of methods
Authors: Chen Gangchi , Fina Leslie J. 
Published: April 2003

AbstractA method capable of quantitative predictions of orientation gradients at the surface of polymers is proposed. It is based on the transformation of variable‐angle attenuated total reflected infrared intensities to absorption coefficients versus depth from the surface. Two alternate approaches have been used to demonstrate the viability of the method: computer simulation and sample analysis. Exact reflected intensities from anisotropic layered systems have been calculated with Fresnel coefficients. The exact intensities are used to reextract the orientation gradient with data transformation. This analysis demonstrates the conditions under which the variable‐angle method is expected to optimally perform. Simulation results clearly indicate high accuracy near the interface and low accuracy at remote distances. Thin films of isotropic and uniaxially drawn isotactic polypropylene are prepared and used as layered systems. Step functions in orientation can be accurately predicted only when some information is known prior to the gradient calculation. In uniaxially oriented thick films of polypropylene, the analysis indicates that the crystal phase is highly oriented at the surface and in the bulk. Within the first 2 microns from the surface, both the amorphous and crystal phases show negligibly small gradients in orientation. © 1993 John Wiley & Sons, Inc.