bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the state of permeant in the membrane and its effect on pervaporation phenomena
Authors: Yoshikawa Masakazu , Matsuura Takeshi , Cooney David 
Published: April 2003

AbstractPervaporation experiments of pure water and 2‐propanol through poly‐dimethylsiloxane membranes were carried out in order to study the effect of the interaction between permeant and membrane material on pervaporation phenomena. From the effect of downstream pressure on the pervaporation rate, the saturation vapor pressure of water in the membrane was determined to be 2.799 × 103 Pa (21.0 mmHg), which is the same as the literature value, whereas that of 2‐propanol in the membrane was estimated to be 5.865 × 103 Pa (44.0 mm Hg), which is 8.53 × 102 Pa (6.4 mmHg) higher than that of pure 2‐propanol. In the differential scanning calorimetry analyses of permeants in the membrane, it was evident that the state of 2‐propanol in the polydimethylsiloxane membrane was different from that of bulk 2‐propanol. On the other hand, the state of water in the membrane was assigned to that of bulk water. Throughout the present study, it was observed that the interaction between permeant and membrane material plays an important role in determining pervaporation phenomena.
Weathering of polystyrene foam on exposure in air and in seawater
Authors: Andrady Anthony L. , Pegram Jan E. 
Published: April 2003

AbstractExpanded extruded polystyrene foam was exposed outdoors in air and floating in seawater. The degradation of the materials was determined by ultraviolet spectroscopy, gel permeation chromatography, and measurement of yellowness, viscosity, and tensile properties. The samples underwent extensive yellowing, reduction in average molecular weight, and embrittlement in the exposed surface layer. Furthermore, the rate of deterioration was shown to be faster in seawater than in air, possibly due to the removal by the seawater of the outer protective yellow‐colored layer formed during early exposure to sunlight.
Free radicals of fibers treated with low temerature plasma
Authors: Chen Jie Rong 
Published: April 2003

AbstractCotton, linen, polynosic rayon, standard rayon, nylon 6, and poly(ethylene terephthalate) (PET) fibers were treated with low temperature plasmas of O2, N2, Ar, CF4, and CO. The relative free‐radical intensities obtained by ESR spectra increased in the following order: linen > cotton > polynosic rayon > standard rayon > nylon 6 ≈ PET and CF4 > CO > Ar > N2 > O2.
Preparation of a water‐permselective composite membrane by the concentrated emulsion method: Its swelling and permselectivity characteristics
Authors: Ruckenstein E. , Chen H. H. 
Published: April 2003

AbstractA water‐permselective composite membrane was prepared by the concentrated emulsion polymerization method. A large volume fraction of an aqueous sodium acrylate solution was dispersed in a small amount of divinyl benzene. Each of the two phases contained a suitable initiator and the continuous phase contained an appropriate surfactant. The concentrated emulsion thus obtained has the appearance and behavior of a gel. The gel was sandwiched between tow glass plates and subjected to polymerization via heating at 45°C for 24 h. The resulting membrane was dried and further employed in several kinds of experiments. The swelling of the membrane in water depends on the pH of water and can be as large as 86. At low pH values, the swelling was very small. The permeation rate of a water‐ethanol mixture was in the range of 96–560 g/m2 h and decreased with increasing alcohol concentration and increasing poly(sodium acrylate) fraction in the membrane. The permselectivity varied between 32 and 235, increasing with increasing poly(sodium acrylate) fraction in the membrane and with increasing or decreasing ethanol concentration (depending upon the composition of the membrane). The activation energy for pervaporation varied between 6.58 and 8.14 kcal/mol, depending upon the composition of the feed. The permselectivity decreased slightly with increasing temperature.
The influence of charge density and steric factor of aminated chloromethyl polystyrene homologs in bilirubin adsorption
Authors: Raghavan D. , Shaligram A. M. , Deshpande D. D. 
Published: April 2003

AbstractBilirubin, a bile pigment, was studied for its extent of adsorption on substituted aminechloromethyl polystyrene by UV spectrophotometry. By performing simple displacement reactions on chloromethyl polystyrene with secondary and tertiary amines, the amount of charge density and steric factor on substituted nitrogen atom have been varied. Adsorption isotherms of bilirubin at 0°C by different amine–chloromethyl polystyrene homologs suggest the existence of electrostatic interaction of polymeric resin with bilirubin moiety. Results of adsorption of bilirubin to polymeric resin have shown that the extent of adsorption of bilirubin depends on the unit charge, and on the structure of the substituted amine–chloromethyl polystyrene. The effects of porosity of resin on bilirubin adsorption have also been discussed.
Synthesis and characterization of new ion‐exchange membranes
Authors: Elmidaoui A. , Sarraf T. , Gavach C. , Boutevin B. 
Published: April 2003

AbstractThe synthesis of grafted polymers of polyethylene (PE) with acrylic acid and N,N‐dimethylamino‐2 ethyl acrylate is performed in two steps. The first one needed the ozonization of powder of PE in well‐defined conditions to obtain an expected activation. The second one consisted in bulk grafting the two monomers by thermal decomposition of the above hydroperoxides and peroxides of the activated PE. After elimination of homoacrylated by selective solubilization, we obtained films by pressing the copolymers either alone or the mixture of the two copolymers to prepare the anion (or cation) exchange membrane and the amphoteric ion‐exchange membrane. The second part of the study deals with the physicochemical characterization of these membranes: thickness, exchange capacity, electrical resistance, transport number, and water content. These characteristics are given for various concentrations of equilibrating solutions and for various pH. The results show that we have perfectly corrected membranes that are competitive with the commercial ones.
Styrene–isoprene block copolymers. II. Hydrogenation and solution properties
Authors: Velichkova R. , Toncheva V. , Antonov C. , Alexandrov V. , Pavlova S. , Dubrovina L. , Gladkova E. 
Published: April 2003

AbstractStyrene–isoprene block copolymers with a different degree of monomer distribution are hydrogenated with homogeneous catalysts. The products are characterized by means of IR and 1H‐NMR spectroscopy, GPC, viscometry, and light scattering. Hydrogenation proceeds without destruction and selectively for olefinic unsaturation. The hydrogenated copolymers are homogeneous in molecular weights and chain composition. The influence of the copolymer structure on the solution properties in selective solvents is established. In cyclohexane an equilibrium between micelle associates and individual polymer coils, monomolecular micelles, or micelle aggregates are observed, depending on the type of the copolymer. The micellization in base‐lubricating oil leads to micelle fractions with a different degree of association.
Grafting onto wool. XXVIII. Effects of acids on gamma‐radiation induced graft copolymerization of ethylmethacrylate onto wool fiber
Authors: Misra B. N. , Chauhan G. S. , Rawat B. R. 
Published: April 2003

AbstractGraft copolymerization of ethylmethacrylate (EMA) onto Himachali wool fiber has been investigated in aqueous medium by mutual gamma irradiation from a Co60 source in air and in nitrogen atmosphere. Percentage of grafting has been evaluated as a function of (i) total dose, (ii) concentration of monomer, and (iii) effect of concentration of different acids such as hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, and acetic acid. Maximum percentage of grafting has been obtained in the presence of sulfuric acid. Following reactivity order of different acids towards grafting has been observed: H2SO4 > HCI > HNO3 > HCIO4 > CH3COOH. A plausible mechanism to explain the effect of acids on percentage of grafting of EMA has been suggested.
Phenol–formaldehyde resin curing and bonding in steam‐injection pressing. I. Resin synthesis, characterization, and cure behavior
Authors: Myers George E. , Christiansen Alfred W. , Geimer Robert L. , Follensbee Robert A. , Koutsky James A. 
Published: April 2003

AbstractTwo different phenol–formaldehyde (PF) resole resins are serving as models in a study aimed at establishing the effects of moisture, temperature, pressure, and time on resin cure and bonding during the pressing of wood flakeboard. This phase of the program had two goals: first, to characterize the two resins in terms of their structure and chemistry during synthesis, aging, and cure—using viscosity measurement, gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and dynamic mechanical analysis (DMA); second, to make a preliminary evaluation of the utility of DSC, FTIR, and DMA for measuring the degree of resin cure. The two resins differed significantly in relative amounts of hydroxymethyl groups and methylene linkages (NMR), in molecular weight and its distribution (GPC), and in reaction rate (as measured by viscosity, DSC, FTIR, or DMA). The degree of cure developed during constant heating rate DSC scans was calculated for a series of maximum DSC temperatures from both the loss in hydroxymethyl groups (FTIR) and the decrease in available exothermic heat (DSC). Agreement between the two methods was quite good, considering the inherent difficulties in quantifying infrared data. For comparison, the degree of cure developed during constant heating rate DMA scans was calculated for a series of maximum DMA temperatures from both the increase in storage modulus (DMA) and the decrease in exothermic heat (DSC after rewetting). Samples that apparently achieved complete cure in the DMA still exhibited significant residual cure potential in the DSC. We attribute the lower apparent cure in the DMA to loss of moisture from samples during the DMA scan, with consequent loss in plasticization and molecular mobility.
Surface modification by continuous graft copolymerization. II. Photoinitiated graft copolymerization onto polypropylene film surface
Authors: Zhang Pei Yao , Rånby Bengt 
Published: April 2003

AbstractA method for photochemically induced graft copolymerization of acrylamide (AM) onto polypropylene (PP) film surface by a continuous presoaking process under nitrogen atmosphere has been developed. After removal of homopolymer formed, ESCA, UV spectroscopy, contact angle, and adhesion measurements confirmed a photografted layer on the surface of the PP film. The results from spectral analysis and surface properties measurements were consistent. The best grafting yield was obtained for 7–10 s irradiation time. Stabilizing additives in the PP film had no evident effect on the photografting. Benzophenone was an efficient photoinitiator for photografting of PP film with AM. An AM concentration of 0.5–1.3M in the presoaking solution was appropriate in the present case. Acetone was the best solvent among the three alifatic ketones tested (acetone, methylethylketone, and methylpropylketone).
Microheterogeneity in PPO/PS blends
Authors: Li S. , Dickinson L. Charles , Chien James C. W. 
Published: April 2003

AbstractProton spin magnetization relaxation in the rotating frame is a simple exponential for poly(2,6‐dimethylphenyleneether) (PPO) (23K)/polystyrene (PS) (9K) blends of various compositions; these blends are truly homogeneous at the spin‐diffusion distance scale of a few nanometers. Blends of PPO with high molecular weight PS exhibit nonexponential decays for the PS component but exponential decays for the PPO component, indicating compositional fluctuation for PS. In some blends, the relaxations are nonexponential for both components. Three factors have been identified to promote microheterogeneity of nanometer dimensions: high polymer molecular weight, increase of temperature, and preparation of blend using solvent that induces crystallization of PPO such as toluene.
Cure behavior of an epoxy–novolac molding compound
Authors: Hsieh T. H. , Su A. C. 
Published: April 2003

AbstractThe isothermal cure of an epoxy–novolac molding compound was studied by means of differential scanning calorimetry (DSC). The glass transition temperature (Tg) of the molding compound increased in an approximately linear manner with conversion (α) during the major part of the cure process. Predictions of an empirical kinetic scheme (established earlier from dynamic DSC results) compared favorably with the present isothermal results in the absence of vitrification. In combination with the gel point conversion (αgel) determined via dynamic rheological analysis and gravimetric measurements, our DSC results indicated that gelation bears no apparent effect on the rate of cure whereas vitrification retards the cure reaction. Based on the measured αgel, the approximate Tg−α relationship, and the thermokinetic results, the time–temperature–transformation diagram of this molding compound was constructed and discussed.
Polymerization of N‐vinylcarbazole by gaseous initiators
Authors: Bhadani Suraj N. , Gupta Sumanta K. Sen , Sinha Arvind K. 
Published: April 2003

AbstractThe polymerization of N‐vinylcarbazole initiated with NO2 and SO2 in dichloroethane has been studied. The kinetics of polymerization were followed gravimetrically. The Polymerization is fast with NO2 but a relatively slow rate was obtained with SO2. The polymerization with these gases appears to be initiated by a charge transfer mechanism.
Effects of spinning conditions on morphology and properties of polyethylene terephthalate fibers spun at high speeds
Authors: Chen Gao‐Yuan , Cuculo John A. , Tucker Paul A. 
Published: April 2003

AbstractFiber spinning of polyethylene terephthalate (PET) was studied at take‐up speeds ranging from 2000 m/min to 7000 m/min under various spinning conditions. Effects of changes in process variables on the molecular orientation, crystallinity, and properties of as‐spun PET fibers are reported. Conventional cross‐flow quench in high‐speed spinning yields fibers with undesirable crimp and asymmetric structure with respect to the fiber axis. Radial‐flow quench eliminates these problems. Changes in other spinning conditions, such as extrusion temperature, throughput or take‐up denier, and molecular weight, may also affect the development of PET fiber structure in the high‐speed threadline.
Dynamic mechanical properties of polypropylene–polyamide blends: Effect of compatibilization
Authors: Liang Zhizhong , Williams H. Leverne 
Published: April 2003

AbstractThe influence of compatibilization on the dynamic mechanical properties of polypropylene (PP) binary blends with polyamide‐11 (PA) has been investigated. In the blends an acrylic acid functionized PP was used as a blend component and compared with nonfunctionized PP over the who concentration range. The results demonstrate that the use of the functionized PP instead of the unmodified one produced blends with different dynamic mechanical properties due to adhesion enhancement between the two phases. The storage moduli E′ of the compatibilized blends vary nearly linearly as a function of composition over a broad temperature region, whereas those of the noncompatibilized ones deviate greatly from linearity, specially at about 50/50 ratio, at which a minimum exists at about room temperature. While the dynamic testing gives no evidence for the variation in the glassy transition temperatures (peak maxima) of the components (PP and PA) in the two types of blends, both the loss modulus (E″) and the loss factor (tan δ) data indicate that the compatibilized blends differ from the noncompatibilized ones mainly in the glassy transition (βrelaxation) process of the PA phase, suggesting that the compatibilization of the blends seems to influence the PA phase more than the PP phase included. But, for the β‐relaxation behavior of the PA in the modified blends, the tan δ spectrum shows a more complex pattern than does the E″. These results are discussed in terms of the morphological texture of the blends and possible chemical or physical interactions between the two consituent polymers.
Catalytic grafting: A new technique for polymer–fiber composites I. Polyethylene–asbestos composites
Authors: Wang Qi , Kaliaguine Serge , Ait‐Kadi Abdellatif 
Published: April 2003

AbstractIn this work we present a new technique to prepare polyolefin‐fiber composites. This technique is based on chemical anchoring of a catalyst on reinforcing agents containing OH groups on their surface and then conducting an olefin polymerization on the supported catalyst. This technique offers the possibility to approach the challenging problems encountered in polymer composites, namely, the reinforcement‐matrix adhesion, the dispersion, and the wetting of the reinforcement by the resin. As a first part of a systematic research, we report on the procedure of fixation of titanium tetrachloride on the surface of asbestos fibers and the Ziegler‐Natta polymerization of ethylene on the surface‐modified fibers. The procedure as well as the structure and properties of the composite were investigated by means of FTIR, atomic absorption, SEM, solvent extraction, and tensile testing. The experimental results show that the Ziegler‐Natta catalyst can be efficiently anchored on the surface of the fibers to conduct successful polymerization and to “synthesize” a new class of polymer composites.
Reactions of glycerol with poly(ethylene ether carbonate) polyols
Authors: Harris Robert F. , Lopez Karen M. 
Published: April 2003

AbstractPoly(ethylene ether carbonate) polyols can be modified by chemical reactions with polyglycol modifiers under conditions of elevated temperatures and reduced pressures. The modifier becomes chemically incorporated into the modified polyol and is used to control properties such as moisture sensitivity, CO2 content, Tg, density, etc. in the resultant polyol. However, glycerol cannot be used as a modifier for poly(ethylene ether carbonate) polyols under the same conditions since it reacts with poly(ethylene ether carbonate) polyols by a transesterification reaction sequence to form glyceryl carbonate. As the temperature is increased, the glyceryl carbonate decomposes to yield glycidol and carbon dioxide. These reactions are conveniently followed by 13C‐NMR. The preparation of glyceryl carbonate by this process has not been previously reported.
Studies in optical properties and optical radiation hardness of polyorganosiloxanes
Authors: Harmon J. P. , Jhaveri T. , Gaynor J. , Walker J. K. , Chen Z. 
Published: April 2003

AbstractA variety of polyorganosiloxanes containing dimethyl, diphenyl, and methylphenyl substituents were studied to determine transparency and optical radiation hardness. Siloxanes show superior optical radiation hardness when compared to optical thermoplastics such as PMMA. Transparency is diminished in polymers containing diphenyl units. This is attributed to the inability to remove traces of the crystalline monomer. Methylphenyl polymers are highly transparent. The maximum attainable refractive index in transparent systems is 1.53.
Studies on the radiation‐induced graft copolymerization of mixtures of n‐butyl acrylate and 2‐hydroxyethyl methacrylate on polyurethane. I. Synthesis and characterization
Authors: Sreenivasan K. , Rao K. V. C. 
Published: April 2003

AbstractModification of polyurethane, by grafting two types of monomers, a hydrophilic and hydrophobic, with an aim to enrich the surface with both hydrophobic and hydrophilic moieties, is attempted. Grafting of 2‐hydroxyethyl methacrylate and n‐butyl acrylate from a mixture of these two onto polyurethane by γ‐irradiation and subsequent characterization of the graft copolymer by infrared spectroscopic method, mechanical characterization, contact angle, and scanning electron microscopy is detailed.
Influence of molecular weight on the thermal and mechanical properties of polyurethane elastomers based on 4,4′‐diisocyanato dicyclohexylmethane
Authors: Hespe Hans F. , Zembrod Alfred , Cama Farhad J. , Lantman Christopher W. , Seneker Stephen D. 
Published: April 2003

AbstractTwo series of segmented polyurethane elastomers based on 4,4′‐diisocyanato dicyclohexylmethane were investigated with respect to their thermal properties and deformation behavior. We used a crystallizable soft segment, 1,4‐poly(tetramethylene glycol), for one series and a noncrystallizable soft segment, 1,2‐poly(propylene glycol), for the other. Both systems exhibited mechanical self‐reinforcement that depended strongly on the deformation rate. We propose a mechanism for the observed stress/strain behavior in terms of two competing processes: (1) the buildup of orientation caused by deformation and (2) the loss of orientation caused by plastic slippage and segmental relaxation during deformation. The kinetics of these processes depend stronly on the deformation rate and overall molecular weight.
Synthesis of macromolecular coupling agents and binders
Authors: Crespy A. , Caze C. , Loucheux C. 
Published: April 2003

AbstractSizes of glass fibers used in composite materials include binders and coupling agents. Usually these types of compounds have a low molecular weight and present two identical reactive groups for binders and two different functions (namely, organic and inorganic groups) for the coupling agents. The aim of this paper was to describe the synthesis of macromolecular binders and coupling agents in order to perform the interphase region. These products appear as difunctional or polyfunctional compounds. Difunctional compounds were obtained by reaction between a telechelic polymer (prepared by anionic polymerization) and alkoxysilane or epoxy groups. Polyfunctional compounds were performed by hydrosilylation reactions between a polysiloxane containing hydrogenosilane functions and vinylsilane, and/or 1‐allyloxy‐2,3 epoxypropane.
Effect of latex concentration on epoxidation of natural rubber (NR) latex
Authors: Vernekar S. P. , Sabne M. B. , Patil S. D. , Patil A. S. , Idage S. B. , Avadhani C. V. , Sivaram S. 
Published: April 2003

AbstractEffect of latex concentration on the extent of epoxidation and physical properties of epoxidized natural rubber (ENR) was evaluated as a function of latex concentration in the range of 20–60% by weight. The epoxidation rate increased with increasing latex concentration. Physical properties and sequence distribution of an epoxy group of ENR with 30 mol % epoxy content was invariant with the latex concentration employed for epoxidation.
Coconut husk lignin. II. Characterization by infrared and nuclear magnetic resonance spectroscopy
Authors: Vázquez‐Torres H. , Canché‐Escamilla G. , Cruz‐Ramos C. A. 
Published: April 2003

AbstractResults of the characterization of coconut husk lignin by infrared (IR) and proton nuclear magnetic resonance (H‐NMR) spectroscopy are presented. Lignin was extracted with both alkaline and organosolv liquors. The IR spectra of dioxane lignin were very similar to those reported for hardwood lignins. Furthermore, these results combined with those obtained from the H‐NMR studies suggest that coconut husk lignin can be classified into the Lm‐type lignins. These lignins are characteristic of the monocotyledon class, of which the coconut palm is a member. The H‐NMR studies showed that anthraquinone significantly inhibited the occurrence of lignin condensation during the alkaline extraction with sodium hydroxide solutions. This inhibition was more intense in the lignin extracted at 150°C than in that extracted at 100°C.