bluuebunny/crossref_metadata_2025_split huggingface dataset:
Permeation of propane and propylene thrugh cellulosic polymer membranes
Authors: Ito Akira , Hwang Sun‐Tak 
Published: April 2003

AbstractCellulosic polymers were tested by measuring their permeabilities of propane and propylene. High permeabilities and selectivities were obtained with ethyl cellulose membranes. Hollow fibers coated with ethyl cellulose were made through a solution coating method. Microporous polypropylene hollow fibers were used as base material. A dense layer of ethyl cellulose about 6–10 μm in thickness was formed on the microporous hollow fiber. The performance of a coated membrane column was tested for the separation of propane and propylene mixture gas. It was concluded that ethyl cellulose membranes have a good potential for the separation of olefins form saturated hydrocarbons.
The morphology of fracture surfaces and mechanical properties of composites of polypropylene with glass fibers having different interface adhesion
Authors: Sova Miloš , Pelzbauer Zdeněk 
Published: April 2003

AbstractFor composites polypropylene–short glass fibers having different interface adhesion, correlation has been proved to exist between the morphology of fracture surfaces, the temperature dependence of impact strength, and the deformational and fracture behavior in tensile loading. The results are interpreted in terms of the mechanism of distortion plasticity for unfilled PP and for filled PP having weak interface adhesion, and on the basis of dilatation plasticity for filled polypropylene with a higher interface adhesion. The transition from the distortion to the dilatation mechanism can be seen in fracture surfaces after tensile destruction in composites possessing a higher interface adhesion.
A method for the calculation of compositions of radical‐chain copolymerizations
Authors: Kuo Jen‐Feng , Chen Chuh‐Yung , Luo Shieh‐Huang , Pan Ting‐Chung 
Published: April 2003

AbstractIn this article the straight‐line relationship between In A and B, where A and B denote the concentrations of the two types of monomers in any reaction period, is examined to exist in the radical copolymerizations of 1.02 ≥ r1r2 ≥ 0.25. Utilizing this observation, we propose an easy‐to‐use compositions calculation method in which a single empirical parameter is included. The method is derived without involving the constant monomer reactivity ratios assumption. The copolymerizations of styrene–methyl methacrylate vinyl chloride–vinyl acetate, methyl methacrylate–vinyl acetate, acrylic acid–acrylamide, methacrylic acid–methacrylamide, and sodium methacrylate–methacrylamide are investigated. The instantaneous and cumulative copolymer compositions and the residued monomer compositions computed by this proposal are in very good agreement with the experimental data.
Gas transport in poly[bis(trifluoroethoxy)phosphazene]
Authors: Hirose Takuji , Kamiya Yoshinori , Mizoguchi Keishin 
Published: April 2003

AbstractThe gas transport parameters of 14 gases in poly[bis(trifluoroethoxy)phosphazene] were determined at temperatures ranging from about 12 to 45°C by the time‐lag method. The phosphazene polymer demonstrated a high diffusivity; rather high crystallinity was expected, though. The permeation data determined were between polydimethylsiloxane and low‐density polyethylene. The most interesting characteristic shown over the course of experimentation is that poly[bis(trifluoroethoxy)phosphazene] has significantly high solubility for CO2, as compared to other gases. The polar side groups—i.e., the electron‐withdrawing trifluoroethoxy parts—which should contribute specific interaction with CO2, were shown to be stronger than their interaction with the polar N2O molecule. The sorption behavior is compared with those of other rubbery polymers, while phosphazene polymer characteristics are also discussed.
Dielectric relaxations in poly(methyl acrylate), poly(ethyl acrylate), and poly(butyl acrylate)
Authors: Ribelles J. L. Gómez , Dueñas J. M. Meseguer , Pradas M. Monleón 
Published: April 2003

AbstractA comparative study is undertaken of the dielectric relaxation spectra of poly(methyl acrylate), poly(ethyl acrylate), and poly(butyl acrylate), taking into consideration the spectra of the corresponding polymers in the series of the polymethacrylates. The three polymers, PMA, PEA, and PBA, present an α relaxation zone clearly separated from the secondary relaxations. Its shape is not altered with temperature, and it is possible to construct a master curve. With increasing length of the side chain, its distribution of relaxation times broadens and the temperature of the maximum of the relaxation decreases. A β relaxation with decreasing intensity as the length of the side chain increases is clearly perceptible in PMA and PEA, but almost not perceptible at all in PBA. In PEA this relaxation appears split into two peaks. Computer simulation of restricted motions of the side chain discard an origin similar to that of the γ relaxation in PPA or PBA for the lowest temperature component of the relaxation, and suggests the conjunction of two rotation mechanisms in this relaxation for the polyacrylates. For the experimental temperatures of our tests a γ relaxation shows up only in PBA. Its apparent activation energy, higher than in related polymers of the polymethacrylate series, suggests that the tighter packing of monomeric units in polyacrylates leads to a significant increase in the intermolecular contribution to the potential energy barrier responsible for the relaxation.
Ultrafiltration membranes obtained by grafting hydrophilic monomers onto poly(vinyl chloride)
Authors: Vigo Fernando , Uliana Claudio 
Published: April 2003

AbstractThe grafting of vinylacetate (VAc) or hydroxyethylmethacrylate (HEMA) onto poly(vinyl chloride) (PVC) has been performed by means of γ‐rays or chemical initiators. The grafted polymer so obtained has been separated by selective extraction and submitted to IR spectroscopy in order to check the amount of grafting. The grafting percentage was measured as a function of the grafting conditions. Using the above‐mentioned polymer, dissolved again in DMF, asymmetric ultrafiltration membranes have been prepared by the phase inversion technique. The membranes have been tested with Dextran solutions. Their performances have been studied as functions of the grafting amount. The values of rejection and permeating flux demonstrated the effectiveness of the treatment in enhancing the performances of PVC ultrafiltration membranes.
The preparation of small polystyrene latex particles
Authors: Brouwer W. M. 
Published: April 2003

AbstractThe effects of several variables in the preparation of small‐sized polystyrene latex particles are described. A semicontinuous preparation using microlatexes obtained by microemulsion polymerization as a seed is compared with a batchwise preparation employing the same ingredients. The particles in the batch products prove to be slightly larger in size but are more narrowly distributed. Furthermore, the effects of both the surfactant type and the ionic strength on the particle size in the batchwise emulision polymerization of styrene are reported. The systems do not obey the linear Smith–Ewart relationship with respect to the micellar surfactant concentration, although in the microemulsion polymerization of styrene the Smith–Ewart relationship is found to be valid with respect to the initiator concentration. Surfactants with a low critical micelle concentration increasingly promote the formation of smaller particle sizes. Salt is found to decrease the particle size when using a strong adsorbing surfactant. However, in the case of a weak adsorbing surfactant, an increase in particle size has been observed above a certain salt concentration.
The supermolecular structure of poly(vinyl chloride)–poly(methyl methacrylate) blends
Authors: Włochowicz Andrzej , Janicki Jarosław 
Published: April 2003

AbstractInvestigations of the supermolecular structure of PVC/PMMA blends, covering a wide range of composition, are presented. It was found that a transition layer exists between PVC and PMMA phases. The thickness of the transition layer is independent of blend composition. The scattering intensity distribution function for blends is characteristic of isotropic, amorphous systems with a completely random distribution of phases. It was shown that scattering intensity distribution function may be used for calculation of a distribution, which corresponds a two‐phase system with sharp phase boundaries. Values of correlation lengths, inhomogeneity lengths, and specific surfaces were then calculated. A model of the supermolecular structure of PVC/PMMA blend was finally proposed.
Synthesis and some properties of anthracene and anthraquinone incorporated poly(vinyl chloride) and the ion exchange resin therefrom
Authors: Biswas Mukul , Majumdar Amitava 
Published: April 2003

AbstractPoly(vinyl chloride) has been modified by chlorine displacement reaction with 2‐anthrol and anthraquinone‐2‐ol. The condensates (PVC‐ACOL and PVC‐AQOL) are insoluble in all solvents common to PVC and have been characterized by elemental and IR spectra analysis. The initial decomposition temperature of these condensates follow the trend: PVC‐AQOL (250°C) > PVC‐ACOL (200°C) > PVC(190°C) and the overall thermal stabilities beyond 60% decomposition follows the same trend. Permittivity and dielectric loss of these condensates sharply fall with increasing applied frequency (10–1.3 ×107 Hz) to a limiting constant value. In contrast, for unmodified PVC these values are low and remain independent of frequency in the same range. Sulfonation of these PVC condensates affords a weak acid resin with COOH and OH ionogenic groups, but no strong sulfonic acid groups due presumably to oxidative degradation of the PVC matrix.
Radiopaque miscible systems composed of poly(methyl methacrylate) and transition and nontransition metal salts: Spectroscopic, thermal, and radiographic characterization
Authors: Cabasso Israel , Smid Johannes , Sahni Suresh K. 
Published: April 2003

AbstractThe preparation of miscible systems containing poly(methyl methacrylate) and cupric nitrate, manganese chloride, praseodymium chloride, and uranyl nitrate is described. The salt was dissolved in the monomer, which was subsequently polymerized. The heavy metal salts impart radiopacity to these plastics and this renders them useful for X‐ray imaging in applications such as medical implants. The polymer–salt systems are characterized on the basis of their infrared spectra, thermal, and radiographic properties, and the formation of complexes between the cations and the carbonyl function of the polymer is discussed. The glass transition temperatures of the salt‐containing polymers are higher than those of the salt‐free polymers, the elevation being dependent on the nature and concentration of the metal salt. Miscible PMMA–uranyl nitrate systems are transparent, glassy plastics and approximately 11 wt % of uranyl nitrate hexahydrate imparts a radiopacity equivalent to that of aluminum.
A comprehensive approach to the stereochemical and physical factors in nucleophilic substitution on PVC in the melt
Authors: Mijangos C. , Gómez‐Elvira J. M. , Martínez G. , Millán J. 
Published: April 2003

AbstractThe nucleophilic substitution reactin of poly(vinyl chloride) (PVC) with sodium benzenethiolate (NaBT) has been studied in the melt with the aim of determining whether a conformational mechanism is applicable under conditions that would apply in the polymer processing. The evolution of unreacted syndio, hetero, and isotactic triads content, and of the apparent molecular weight has been followed by 13C‐NMR and GPC, respectively. The kinetic behavior was defined by choosing appropriate mixing conditions of temperature, shear stress, load, and amount of plasticizer. In all cases the kinetic curves attain a plateau after a rather fast reaction period has elapsed. The conversion at the plateau, that is, the reaction efficiency, proved to depend linearly on the amount of nucleophile and is hardly influenced by the mixing conditions for a given stoichiometric composition. The mixing conditions have been found to affect markedly the kinetics but to be quite inoperative on the evolution of both the content of unreacted tactic triads and the apparent molecular weight with degree of conversion. The results are discussed by taking into consideration those previously obtained in solution.
Halogen‐induced chemical copolymerization of pyrrole with N‐methylpyrrole
Authors: Neoh K. G. , Kang E. T. , Tan T. C. , Tan K. L. 
Published: April 2003

AbstractSimultaneous chemical copolymerization and oxidation of pyrrole and N‐methylpyrrole by bromine an iodine has been carried out. The composition of the copolymes can be effectvely controlled by varying the monomer feed ratio. From elemental analysis the copolymer composition and the monomer reactivity ratios have been determined. As the copolymer composition changes, the IR absorption spectra show changes in the intensity of certain bands. In bromineinduced polymerization, the electrical conductivity, the electrical conductivity, thermal stability, and bromine content of the copolymer complex decrease with increase in N‐mthylpyrrole fraction. X‐ray photoelectron spectroscopy data suggest that a fixed fraction of bromine is incroporated as covalent bromide in the copolymer complex. When iodine is used the halogen content do not show substantial differences among the copolymers but the electricdal conductivity and thermal stability of the copolymers also decrease with increase in N‐methylpyrrole fraction.
Polyaramides containing arylene sulfone ether linkages
Authors: Idage S. B. , Idage B. B. , Vernekar S. P. 
Published: April 2003

AbstractPolyamides containing arylene sulfone ether linkages were synthesized from 4,4′[sulfonybis (p‐phenyleneoxy)] dibenzoyl chloride (SPCI), 3,3′‐[sulfonylbis (p‐phenyleneoxy)] dibenzoyl chloride (SMCl) and various aromatic diamines (ARD), by solution and interfacial polymerization techniques. In solution polymerization, the effect of various acid acceptors such as propylene oxide (PO), lithium hydroxide (LiOH) in the presence of lithium chloride (LiCl), and triethylamine (TEA) on teh molecular weight of the olyamides was studied. The effect of structure of studied. The effect of structur of various aromatic diamine sof molecular weight and thermal properties of polyamides was also studied. The polyamides prepared were characterized by solution viscosity, elemental analysis thermo‐gravimetric analysis, differential scanning calorimetry, and x‐ray diffraction. Physical and thermal properties of polyamides prepared from SPcl and Ard were compared with the polyamides prepared from SMCl and ARD.
Synthesis, characterization, and propellant binder studies of new polyurethanes
Authors: Kothandaraman H. , Venkatarao K. , Thanoo B. Chithambara , Krishnamoorthy V. N. 
Published: April 2003

AbstractHydroxy‐terminated ether‐ and ester‐based prepolymers more suitable for propellant binder applications were prepared from tetrahydrofuran, propyleneoxide, and various discarboxylic acids. Polyurethanes were prepared from these prepolymers with various diisocyanates such as hexamethylenediisocyanate, toluene diisocyanate, and diphenylmethanediisocyanate, and the mechanical properties such as hardness, tensile strength, and elongation of these polyurethane elastomers were compared. The thermal degradation study of these polyurethanes was studied in the atmosphere of oxygen. Composite propellants were formed using these prepolymers as binder resins, toluene diisocyanate as the curing agent, ammonium perchlorate as the oxidizer, and aluminum as the fuel. Propellants having two different solid loadings (85 and 82%) were made and compared with respect to their unloading slurry viscosity and mechanical properties. The tensile strength, elongation, and ballistic performance parameters (theoretical) of these new propellant systems were promising.
Characterization of the isothermal crystallization of poly(ethylene terephthalate) by microhardness measurements
Authors: Pastor J. M. , González A. , De Saja J. A. 
Published: April 2003

AbstractThe two‐stage isomerization isotherms of poly(ethylene Terephthalate) have been followed through microhardness analysis. A great variation in microhardness values seems to prove the increase of the strength and stiffness of the samples produced by the secondary isomerization. A smaller variation is observed for the primary isomerization.
Effect of intramolecular hydroxyls on electron beam polymerization and photopolymerization of acrylate monomers
Authors: Itoh Maki , Shiota Toshiaki 
Published: April 2003

AbstractThe effect of intramolecular hydroxyls on the electron beam polymerization and photopolymerization of monoacrylate monomers has been studied. In both polymerization methods, the rate of polymerization of monoacrylate monomers containing a hydroxyl was several times faster than those without hydroxyls. This can be partly explained by the higher viscosity of the hydroxyl containing monomer, resulting in a decrease in the termination rate constant to increase the polymerization rate. In electron beam polymerization, an increase in initiating species by the generation of radicals from the hydroxyls can also accelerate the polymerization.
Effect of electron beam radiation on the mechanical and thermal properties of poly(4‐methylpentene‐1)
Authors: El‐Naggar A. M. , Lopez L. C. , Wilkes G. L. 
Published: April 2003

AbstractThe changes in the mechanical and thermal properties of electron‐beam‐irradiated PMP of two different molecular weights (〈Mw〉 = 9.2 × 105, 〈Mw〉 = 1.8 × 106) have been studied. Electron beam (EB) irradiation was performed either in a nitrogen or air atmosphere to a maximum dosage of 40 Mrad. Stress–strain behavior of the irradiated materials show that the lower molecular weight polymer is more affected within this dose range than the higher molecular weight material. The modulus of both PMP materials (at 23°C), however, was not affected by EB. Moreover, it was observed that by increasing radiation dose up to 10 Mrad the occurrence of yielding disappeared in the case of the lower molecular weight system but was still found in the high molecular weight material up to 20 Mrad. The elongation at break of both PMP materials was systematically decreased by increasing the dose level. The rate of stress–relaxation of irradiated samples increased as dosage increased. It is believed that oxidative degradation is promoted as a result of irradiation which induces chain scission. This result was confirmed by GPC analysis which showed that, by increasing radiation dose, the molecular weight systematically decreased. DSC measurements used to investigate the changes in thermal properties showed that the melting temperature and heat of fusion decreased as the dose increased. An interesting feature of the DSC studies was the presence of an endothermic doublet in the melting behavior that transformed into a single peak following irradiation.
Surface lubrication of polymer films by photoinduced graft polymerization
Authors: Uyama Y. , Tadokoro H. , Ikada Y. 
Published: April 2003

AbstractFilms of nylon 6, polypropylene, and ethylene–vinyl acetate copolymers were graft polymerized with acrylamide or dimethylacrylamide to render the hydrated surfaces slippery. Following UV irradiation in air, the films were placed in the aqueous monomer solution and then either heated to 50°C after degassing or UV‐irradiated in the presence of a small amount of riboflavin without degassing to effect graft polymerization. The graft polymerization altered the films from the hydrophobic and nonlubricating to the hydrophilic and slippery surfaces. To evaluate the surface lubricity, the coefficient of friction (μ) against a glass plate in water was determined with the help of a tensile testing machine. The μ value for the films surface‐grafted with acrylamide up to 30 μ g cm−2 was reduced to less than 0.05, regardless of the substrate polymers.
A study of the low temperature nitration of cellulose in mixed acids
Authors: Munro H. S. , Short R. D. 
Published: April 2003

AbstractThe low temperature surface and bulk nitration of cellulose has been investigated by electron spectroscopy for chemical analysis (ESCA), 13C‐NMR and X‐ray diffraction. Acid mix composition has been probed at room temperature and at low temperatures (0–20°C) by Raman spectroscopy. This multitechnique approach has been employed to elucidate the behavior of surface degree of substitution (DOS) with acid mix composition over a 40°C temperature range. The data obtained have prompted a reinterpretation of previously reported work. Surface “equilibrium DOS” is shown to be established within 1 s at all temperatures investigated. but, at lower temperatures (> 5°C) the surface DOS as monitored by ESCA is observed to “dip” after immersion times of t < 5 s. This change in DOS is correlated with major structural changes in the fiber as observed by SEM. At low temperatures, e.g., −15°C, nitration is shown to be complete throughout the cellulose fiber after 10 h nitration. Solution state 13C‐NMR is used to compare the nitrate ester substitution distribution in cellulose nitrates prepared from acid mixes of the same composition at different temperatures.
Selective sorption of heavy metal thiocyanate complexes on crown ether resin
Authors: Hayashita Takashi , Noguchi Hiroaki , Oka Hisashi , Igawa Manabu , Takagi Makoto 
Published: April 2003

AbstractThe sorption behavior of heavy metal thiocyanate complexes was investigated for dibenzo‐18‐crown‐6 (DB18C6) resin and bis[2‐(o‐methoxyphenoxy)ethyl]ether (BMPE) resin. The DB18C6 resin showed a high sorption ability and the degree of zinc sorption increased significantly with thiocyanate concentration. This behavior was not observed for BMPE resin. The sorption behavior was influenced by the countercation species, and the degree of sorption of zinc ions showed the maximum when the potassium thiocyanate was used as a complexing salt. The sorbed species appear to be KZn(SCN)3, K2Zn(SCN)4 in the potassium thiocyanate system, and Zn(SCN)2 in the lithium thiocyanate system, respectively, according to analysis of the sorption equilibrium. Sodium and ammonium thiocyanate systems show an intermediate behavior of the two. The sorption selectivity for DB18C6 resin depended not only on the hydrophobic nature of heavy metal thiocyanate complexes but also on the stabilization of counter cation species with crown ether matrix, and the sorption selectively was found to be effectively controlled by countercation species according to the cation‐chelation mechanism.
A new type of solid‐state crystalline photopolymerization
Authors: Xiaolin Zhang , Youan Mao 
Published: April 2003

AbstractA new type of solid‐state crystalline photopolymerization is researched in which, different from the topochemical polymerization, vinyl monomers are filmed under the induction of other macromolecular compound, crystallized, and polymerized after photoirradiation. Therefore, it may be also known as induction‐filming polymerization. The crystalline polyacrylamide film with large spherulite structures was obtained from the crystalline acrylamide by this means. Microscopy, differential scanning colorimetry, and infrared measurements were carried out. Mechanism is proposed for the induction‐filming polymerization involved.
An anion‐permeable polymeric coating for the protection of a semiconductor photoelectrode against decomposition
Authors: Bolts J. M. , Mariella R. P. 
Published: April 2003

AbstractAn anion‐permeable polymeric film has been applied to the surfaces of cadmium sulfide photoanodes to decrease the rate of electrode corrosion which is observed during the photoelectro‐chemical oxidation of aqueous species. Although the rate of surface corrosion was reduced, film adhesion problems were observed.