bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of uv‐curable acrylated urethane prepolymers, I. Effects of reactive diluents and relative humidity on physical properties
Authors: Yildiz Emel , Güngör Atilla , Yildirim Hüseyin , Baysal Bahattin M. 
Published: April 2003

AbstractA UV‐curable acrylated urethane prepolymer was synthesized from tolylene‐2,4‐diisocyanate (TDI), a polyether polyol (Arcol 1131) and endcapped with 2‐hydroxyethyl methacrylate (HEMA) by addition reaction in the presence of dibutyltin dilaurate as catalyst. UV curing was performed with either diethylene glycol diacrylate or thiodiethylene glycol diacrylate as reactive diluent.The effects of reactive diluent types, their concentrations and the humidity of environment on mechanical properties of cured films were investigated. Changes in the tensile strength, elongation and Young's modulus values of the cured films upon addition of reactive diluents with different concentrations were related to the effect of the diluent on the crosslinking density of cured films.The increase of relative humidity from 50 to 95% caused a decrease of tensile strength and Young's modulus values of cured films. It is proposed that the decrease of these physical properties in high relative humidity is due to the formation of hydrogen bonding in polymer chains caused by water molecules.
Preparation and characteristics of immobilized glucose oxidase on membranes of photosensitive polymers
Authors: Liu Jui‐Hsiang , Chung Yi‐Chang 
Published: April 2003

AbstractA study of the immobilization of glucose oxidase on a poly(vinyl alcohol) (PVAL) membrane in the presence of UV sensitizers was carried out. Enzyme membranes were prepared from PVAL‐diazoresin and PVAL‐sensitizer systems, crosslinked by means of UV irradiation. An effective enzyme electrode was developed by using the immobilized glucose oxidase membrane, and its characteristics were investigated. The effects of the concentration of sensitizers in poly(vinyl alcohol) and UV irradiation time on the degree of insolubility as well as the activity yield of the membrane were examined for the immobilized glucose oxidase using glucose as a substrate. Temperature and pH dependences of the relative activity, stability in repeated use, storage stability and calibration plots of the enzyme membranes were evaluated. The unstability phenomenon, found in the initial use of the immobilized glucose oxidase membrane, which was prepared from PVAL‐sensitizer system, was also investigated.
Plasma treatment of polyethylene ultrafiltration membranes
Authors: Bryjak Marek , Gancarz Irena 
Published: April 2003

AbstractThe effect of plasma treatment of polyethylene ultrafiltration membranes on fouling and cleaning phenomena during filtration of bovine serum albumin solutions is discussed. Air‐plasma of 2.45 GHz raises the membrane surface hydrophilicity from 0 up to 60%. The flux is maintained at 90–99%. Plasma‐treated membranes are easier to clean than untreated polyethylene membranes. Despite that, the plasma‐modified membranes are susceptible to more intensive deposition of albumin.
Temperature/rate dependence of yield and fracture behaviour of phenolphthalein poly(ether ketone)
Authors: Han Yanchun , Yang Yuming , Li Binyao , Feng Zhiliu 
Published: April 2003

AbstractThe rate/temperature dependence of yield stress, tensile modulus and crack opening displacement of phenolphthalein poly(ether ketone) (PEK‐C) has been investigated. The rate/temperature dependence of crack opening displacement and the correlation established between stress intensity factor, KIC, yield stress, and type of crack growth suggest that the extent of crack tip blunting largely governs the relative toughness of PEK‐C and induces transitions in the types of crack growth observed. A quantitative expression is then presented which successfully describes the fracture toughness values over a wide range of temperatures and rates.
Hydroxamic acid esters and oximes as isocyanate blocking agents. Study on thermal dissociation
Authors: Quérat Evelyne , Tighzert Lan , Pascault Jean‐Pierre 
Published: April 2003

AbstractBlocked isocyanates were prepared and their thermal dissociation into isocyanates and blocking agents was studied. Three blocked versions of 4,4′‐diphenylmethane diisocyanate (4,4′‐MDI) were synthesized. The selected blocking agents were 2‐butanone oxime (methyl ethyl ketoxime, MECO), ethyl acetoacetate oxime (EAO) and benzyl methacrylohydroxamate (BMH), in order to compare their temperature of dissociation (Td). Chemical titration of —NCO groups was tested as suitable technique to follow the unblocking with the temperature. Confirmation of the results by infrared spectroscopy was successful with the hydroxamic ester as blocking agent. Thermodynamic parameters were evaluated for the BMH‐MDI adduct and allowed to predict the free —NCO ratio at high temperatures.Benzyl methacrylohydroxamate can be used as blocking agent and the blocked system shows lower unblocking temperature than the usual oxime‐blocked isocyanates.
Adsorption of cis‐1,4‐polyisoprene at solid/liquid interface
Authors: Vangani Veena , Rakshit Animesh Kumar 
Published: April 2003

AbstractThe adsorption of cis‐1,4‐polyisoprene on alumina and silica gel was studied at three temperatures. The solvents used were toluene, chlorobenzene and various mixtures of both. The adsorption from the mixtures of the solvents was much less than from either of the pure solvents. The amount of adsorption was an inverse function of temperature. The thermodynamic quantities of adsorption at infinite dilution were obtained by extrapolation and at isosteric conditions. They were computed and discussed for all the systems.
Metal ion binding properties of synthetic vinyl resins
Authors: Rivas B. L. , Maturana H. A. , Pereira E. 
Published: April 2003

AbstractThe synthesis of a water‐insoluble chelating resin was carried out by radical copolymerization of 4‐vinylpyridine and N‐hydroxymethyl acrylamide with subsequent crosslinking. Both the crosslinked reference homopolymers of 4‐vinylpyridine and N‐hydroxymethyl acrylamide were also synthesized. The resins were characterized by elemental analyses and FT‐IR spectroscopy. The ability of these resins to bind copper(II), iron(II), iron(III) and uranyl ions as well as the elution of the metal ions from the loaded resins were studied. For uranyl ions, pH 1 was the optimum sorption pH value for all the resins. Sorption selectivity from the binary mixture Cu(II) + U(VI) was studied at the optimum sorption pH value. Finally, the uranium(VI) sorption isotherms, binding constants, and ΔG°, ΔH° and ΔS° corresponding to the uranium(VI) sorption process were calculated.
Dyes for nonlinear optics prepared from 2‐hydroxyethyl methacrylate. Nonlinear properties of the resulting copolymers
Authors: Monthéard Jean‐Pierre , Chatzopoulos Farroudja , Amine Hassan El , Cachard Alain , Trouillet Alain 
Published: April 2003

AbstractDyes for nonlinear optics have been synthesized in two steps from 2‐hydroxyethyl methacrylate (HEMA), 4‐carboxybenzaldehyde and various substituted anilines. The obtained dyes (aromatic imine esters of HEMA) have been copolymerized with styrene, the copolymers characterized by DSC as well as IR, 1H NMR and UV‐VIS spectroscopy, and studied for their nonlinear properties. The d31 and d33 nonlinear coefficients proved to be dependent on the dye content of the copolymers and on the nature of electrondonating groups.
Study of the surface properties of ultrathin films of poly(dimethylsiloxane)‐polyamide multiblock copolymers
Authors: Kishida Akio , Furuzono Tsutomu , Ohshige Taka‐aki , Maruyama Ikuro , Matsumoto Takeo , Itoh Haruhiko , Murakami Mikio , Akashi Mitsuru 
Published: April 2003

AbstractUltrathin films of poly(dimethylsiloxane)‐polyamide copolymers (PAS) with different silicone contents were prepared by the methods of water casting and spin coating. The surface properties of the films were investigated in detail using contact angle measurements and X‐ray photoelectron spectroscopy (XPS). The water‐cast films were thin enough to be applicable as laminate films for an artificial lung or an air‐separator for oxygen‐enrichted air. Uniform and ultrathin films were obtained by the spin coating method. XPS and contact angle measurements suggested that poly(dimethylsiloxane) segments were condensed at the outermost surface of spin‐coated PAS films. XPS measurements also revealed that the surface properties of PAS were affected by the molding method, especially the solvent evaporation conditions.
Effect of a curing accelerator on the glass transition temperature of non‐stoichiometric epoxy amine networks
Authors: Strehmel Veronika , Deltschewa Kalina , Häusler Karl‐Georg , Schröter Klaus 
Published: April 2003

AbstractNetworks were prepared from Bisphenol A diglycidylether and 4,4′‐diaminodiphenylmethane both in the presence of different amounts of imidazole and in the absence of any accelerator. The ratio of epoxy groups to amino hydrogen was varied: the networks were made with amino hydrogen excess, a stoichiometric ratio of epoxy groups to amino hydrogen, and an epoxy excess.The resulting networks were investigated by thermomechanical analysis, by torsion pendulum analysis and by uniaxial compression modulus measurements in the rubbery‐plateau zone. Further characterization was done by sol gel analysis of the cured samples.It was shown that imidazole does not significantly influence the glass transition temperature and the soluble content of the samples of an excess of amino hydrogen was used. In the case of a stoichiometric ratio of epoxy groups to amino hydrogen and in the case of an epoxy excess, imidazole considerably influences the glass transition temperature of the networks. A dependence of the soluble content of the samples on imidazole concentration used for network synthesis was found mainly in epoxy excess systems.
Functionalization of carbon fibres
Authors: Palma Enrique , Ibarra Luis 
Published: April 2003

AbstractThis work reports on a study conducted to achieve carbon fibre functionalization by means of a diazide derivative(p‐(azidosulfonyl)benzoyl azide) in two stages. The first stage comprises surface oxidation of the fibres, which causes an increase of the number of superficial COOH groups. During the second stage the oxidated fibres are brought to react with the diazide derivative via the isocyanate group, obtained by means of the Curtius transposition of the carbonyl azide groups. Fibre oxidation depends on reaction time, following a similar patterns as the one described for carbon black particles. Oxidized fibres functionalization is evidenced both in the progressive decreases in SO2N3 groups in the reagent solution and through differential scanning calorimetry analysis (DSC), which shows an exothermal peak around 190°C due to the decomposition of the azide grafted onto the carbon fibre.The degree of attainable functionalization is a function of COOH groups concentration, generated during fibre oxidation, and the ratio of the functionalizing agent with regard to the carboxy groups formed.
Zum reaktionsverhalten von resol‐ und novolak‐modellen mit säureanhydriden
Authors: Böschel Dorit , Fedtke Manfred 
Published: April 2003

AbstractBenzylalkohol und p‐Kresol wurden als Modellverbindungen für Phenolharzvorstufen mit Bernsteinsäureanhydrid, Hexahydrophthalsäureanhydrid und Citraconsäureanhydrid umgesetzt. Das Reaktivitätsverhalten von 2,6‐Dimethylol‐p‐kresol mit den genannten Anhydriden wurde näher untersucht. Es wurde nachgewiesen, daß bei der Umsetzung mit Citraconsäureanhydrid die phenolische Hydroxygruppe erhalten bleibt und der entstandene Ester in zwei Modifikationen vorliegt. Die Carbonsäureanhydride wurden ferner mit höhermolekularen Resol‐ und Novolakmodellen umgesetzt.
Studies on curing characteristics of natural rubber‐, nitrile rubber‐, and silicone rubber‐based filled compounds in the presence of boron compounds
Authors: Maity S. K. , Chakraborty K. K. 
Published: April 2003

AbstractThe influence of four different boron compounds (boron carbide, boron nitride, boron oxide and disodium tetraborate decahydrate) on the curing characteristics of carbon black‐ and silica‐filled conventional natural rubber‐, nitrile rubber‐, and silicone rubber‐compounds has been studied. The curing parameters have illustrated the individual action. Rheographs have been analysed through the application of CoraN's model. The kinetic parameters have revealed the effects of the boron compounds on different stages of cure. The crosslink density has been assessed from swelling for comparison with the related parameters.
Sulfobetaine polyurethane ionomers, 5. Tensile properties of polyether polyurethane ionomer and related compounds with Co2+ and Pb2+
Authors: Diaconu I. , Coman P. , Buruianǎ T. 
Published: April 2003

AbstractStress‐strain properties of sulfobetaine polyurethane ionomer based on polyether were studied comparatively to the non‐ionic polyurethane and derived compounds with Pb2+ and Co2+. Sulfonation and treatment with H2S improve the tensile properties due to the increased phase segregation and to the semiconducting microphases formed by clustering of metal sulfides, respectively. Complexation with Pb2+ and Co2+ diminishes the tensile properties owing to the partial neutralization of ionic centers.
Novel biodegradable copolyamides based on adipic acid, isophorone diamine and α‐amino acids, 3. Synthesis, study of properties and evaluation of their biodegradability for food packaging applications
Authors: Arvanitoyannis Ioannis , Nikolaou Eleftherios , Yamamoto Noboru 
Published: April 2003

AbstractNovel biodegradable copolyamides were synthesized by melt polycondensation. Statistical copolymers were produced by the incorporation of α‐amino acids showing a gradual increase in their Tg but a decrease in their tensile strength followed by higher susceptibility to alkali hydrolysis which was confirmed with GPC measurements. The amorphous nature of these novel copolyamides was confirmed with the aid of wide‐angle X‐ray diffraction patterns and differential thermal analysis. FT‐IR spectra of the copolymers confirmed the existence of the amino acid moiety. These novel biodegradable copolyamides are expected to find application either on their own in the fields of food packaging and agriculture (disposable plastics) or as a part of composites, as sutures for fixation of macroscopic implants.
Characterization of thermoplastic poly(ethylene terephthalate)‐glass fibre composites, 2. Mechanical behaviour
Authors: Gauthier Catherine , Chauchard Jacques , Chabert Bernard , Trotignon Jean Pierre 
Published: April 2003

AbstractThe aim of this study was to understand how changes in processing conditions affect the morphology and ultimately mechanical performances of unidirectional poly(ethylene terephthalate) / glass fibre composites. In a previous paper, we have presented the influence of fibres on the crystallization kinetics and on the matrix morphology of poly(ethylene terephthalate) (PET), considering fusion‐crystallization conditions, thermal stability and the addition of nucleating agents in the matrix (talc or sodium benzoate). Based on the results of that crystallization study, various processing conditions were implemented on compression‐moulded plated made from PET‐glass pultruded ribbons. Short‐term (dynamic and static) shear tests and long‐term flexural fatigue tests were performed to characterize the effects of moulding conditions. The mechanical results were analysed considering both processing conditions and microstructural parameters.
Yield behaviour and viscoelastic interpretation by activation volume of phenolphthalein polyether ketone
Authors: Han Yanchun , Yang Yuming , Li Binyao , Feng Zhiliu 
Published: April 2003

AbstractPhenolphthalein polyether ketone (PEK‐C) exhibits a marked tensile yield behaviour. The yield stress depends on strain rate and the activation volume V could be evaluated from the data of the yield stress. From the creep and stress relaxation behaviour, V could also be evaluated. So the yield behaviour can be interpreted by the viscoelasticity.
Electrokinetic measurements on porous polysulfone membranes
Authors: Schwarz Simona , Jacobasch Hans‐Jörg , Wyszynski Danuta , Staude Eberhard 
Published: April 2003

AbstractThe surface properties of porous ultrafiltration membranes were determined by means of the streaming potential. The membranes were prepared from chemically modified polysulfone through a phase inversion process. The chemical reactions were carried out in such a way that the resulting polysulfone either was fitted out with chloromethyl substituents or with quaternary ammonia groups. Due to this, the surface of the membranes cast from these materials were either neutral or positively charged. In aqueous solution, ion adsorption as well as dissociation can occur at the surface of the membranes. This can be demonstrated by streaming potential measurements at different pH values, but constant ionic strength. From the calculated zeta potential using a recently developed model, evidence can be given on the dissociation constants of acidic and basic functional groups on the surface of the membranes and on the amount of charges within the shear plane adjacent to the membrane. Using solutions which contained surfactants, qualitative information on the amount of charges within the capillaries of the membrane can be obtained. In the range from 20 to 70°C no temperature dependency of the zeta potential could be observed.
Synthesis of block copolymers by using polysilanes
Authors: Yücesan Dilek , Hostoygar Halil , Denizligil Selçuk , Yagci Yusuf 
Published: April 2003

AbstractPoly(methyl phenyl silane) was used to photoinitiate the polymerization of methyl methacrylate. Poly(methyl methacrylate) (PMMA), obtained this way, contains remaining polysilane chains. Photolysis of this PMMA in the presence of vinyl monomers such as styrene makes it possible to prepare block copolymers. Such PMMA prepolymers were also used to induce the polymerization of cyclohexene oxide through formation of PMMA‐attached silyl radicals and subsequent oxidation to the corresponding ions in the presence of N‐ethoxy‐2‐methylpyridinium hexafluorophosphate resulting in the formation of a block copolymer.
Action of some organophosphonic compounds on a diglycidyl ether‐bisphenol‐A epoxy resin
Authors: Petreus Oana , Popescu Florin N. , Caşcaval Constantin N. 
Published: April 2003

AbstractThe effect of three organophosphonic compounds on the thermooxidative degradation of the uncured diglycidyl ether‐bisphenol‐A epoxy resin was investigated, using infrared spectroscopy, thermogravimetry, differential thermogravimetry, static pyrolysis, pyrolysis‐gas chromatography and elemental analysis. The results obtained indicate that additives with phosphorus and chlorine or nitrogen in molecules exercise an influence upon the degradative process of uncured resin by catalysing its decomposition in the lower temperature region. At the same time, the tested additives promote the formation of highly thermostable and non‐flammable structures in the solid residue.
Grafting of acrylonitrile onto bagasse dissolving pulp with KMnO4/oxalic acid system
Authors: El‐Torky Alaa M. M. , El‐Masry Ahmed M. , El‐Fattah Ali H. Abd 
Published: April 2003

AbstractBagasse dissolving pulp was grafted with acrylonitrile by using a KMnO4 oxalic acid redox initiator system. The effects of monomer concentration, reaction time, initiator concentration, acid concentration and reaction temperature were investigated.
Activity of carbon black as a filler in different elastomeric matrices
Authors: Ślusarski L. , Zaborski M. , Donnet J. B. 
Published: April 2003

AbstractActivity of carbon black toward natural, butyl, butadiene, butadiene‐styrene and butadiene‐acrylonitrile rubber has been evaluated. Peroxide, sulfur donor, sulfur/accelerator systems and also tris(2‐methyl‐1‐aziridinyl)phoshine oxide as crosslinking substances were used. Different activity parameters were taken into consideration. From the results it follows that activity of carbon black depends not only on its properties but also on the type of the elastomer matrix. An effect of chain flexibility, unsaturation degree, crosslinking density and chemical structure of the network has been observed.
Modification of melamine‐formaldehyde moulding compounds with ethylene/vinyl acetate copolymers
Authors: Braun Dietrich , Unvericht Reinhard 
Published: April 2003

AbstractMelamine‐formaldehyde moulding compounds (MF) were modified by mechanical mixing with ethylene/vinyl acetate copolymers (EVA) and with partially hydrolysed EVA. Ether linkages between the hydrolysed material and the MF resin improve the mechanical properties of the transfer moulded parts containing the hydrolysed material compared to those made with EVA. The use of both modifying polymers improves the ductility and, in case of the partially hydrolysed material, the postshrinkage of the extremely rigid MF matrix, as long as the modification polymer content is kept low. On the contrary, Young's modulus and the heat deflection temperature are deteriorated. The improvement in impact strength by use of those uncrosslinked polymers is still insufficient.
Synthesis of highly porous styrene‐divinylbenzene copolymers prepared in the presence of 2,2,4‐trimethylpentane
Authors: Djahièche Abderrahim , Rabia Idir , Revillon André 
Published: April 2003

AbstractA large number of styrene‐divinylbenzene copolymers (St‐DVB) were synthesized using 2,2,4‐trimethylpentane as pore‐forming agent. Diluent and crosslinking agent (DVB) contents were varied in the ranges 20–60 vol.‐% and 2–40 vol.‐%, respectively, to generate various St‐DVB networks. Network features as apparent and skeletal densities, pore volume, mean pore diameter, specific surface area and pore size distributions were measured by mercury porosimetry. A compressing process occurring at the beginning of each measurement has been revealed and measured. Depending on the two synthesis parameters, the changes in pore diameter distributions are discussed. Those results, combined with the calculated average pore diameter and microscopy observations, allow to conclude that the synthesized matrices have a microspheres‐based structure with a network‐overlapping process occurring over 50 vol‐% of dilution. A macroporosity domain has been defined for networks having specific surface areas greater than 130 m2/g.
Synthesis and characterization of N‐alkylated polyamide‐imides
Authors: Choi Kil‐Yeong , Yi Mi Hie 
Published: April 2003

AbstractNew aromatic polyamide‐imides (PAI) containing various alkyl substituents were prepared by the substitution reaction of Torlon® 4203L (commercialized PAI resin) with the corresponding alkyl halides such as methyl iodide, ethyl iodide, and n‐butyl bromide. The resulting amorphous PAIs with glass transition temperatures ranging from 238 to 276°C had inherent viscosities in the range of 51 to 53 mL/g. These polymers were readily soluble in aprotic polar solvents such as N‐methylpyrrolidone, dimethylformamide, dimethyl acetamide, etc. Furthermore, the incorporation of various alkyl substituents into amide groups of the PAI resin increased the melt processability, but slightly decreased the thermal properties compared with conventional PAI resin. The melt viscosities of resulting PAIs determined at 330°C under the frequency of 10‐1 rad/sec were in the range of 103–105 Pa.s. On the other hand, the modified PAIs showed significantly lower melt viscosities than Torlon® 4203L, which was almost comparable to the conventional polyetherimide, Ultem‐1000.