bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of a polyacrylamide chelating resin and applications in metal ion extractions
Authors: Latha A. Gomathy , George Benny K. , Kannan K. G. , Ninan K. N. 
Published: April 2003

AbstractA series of differently crosslinked polyacrylamide chelating resins were prepared, using N,N′‐methylene‐bis‐acrylamide as the crosslinking agent. The crosslinked resins were functionalized by the reaction with ethylene diamine to get amino group capacities varying from 4.2 to 1.1 mequiv/g. The maximum adsorption capacities of the lightly crosslinked resin for Fe3+, Fe2+, Ni2+, and Cu2+ are 3.62, 4.22, 1.48, and 1.67 mequiv/g, respectively. The adsorbed metal ions can be quantitatively desorbed. The adsorption rate and the influence of pH on the adsorption of metal ions were examined. The resins can be used for the separation between different metal ions as well as the ions in different valence states (e.g., Fe3+ and Fe2+). The resin is amenable for continuous process and can be regenerated several times.
Rolling and roll‐drawing of ultrahigh molecular weight polyethylene reactor powders
Authors: Wang Li‐Hui , Porter Roger S. 
Published: April 2003

AbstractUltrahigh molecular weight polyethylene (UHMWPE) reactor powders have been found to be processable in the solid state by the techniques of rolling and roll‐drawing. Plates of compacted UHMWPE reactor powder were prepared below their melting points. These plates were then rolled at 124°C. The maximum uniaxial draw ratio (DR) obtained by multiple rolling was about 10. In additional experiments, rolled plates of a DR of 6 were further drawn by tensile stretching at a temperature of 135°C. The specimens prepared by rolling and by the two‐stage draw were characterized by tensile measurements, differential scanning calorimetry (DSC), and X‐ray diffraction. Results show that, on rolling alone, the tensile modulus and tensile strength achieved were 3 GPa and 42 MPa, respectively, at a DR of 9.6. The rolled plates were effectively drawn further to a total DR of 86. Such highly drawn films exhibited tensile moduli and tensile strength up to 81 and 1.3 GPa, respectively. A high crystallinity and high crystal orientation were also obtained by the two‐stage draw.
Polystyrene/polyethylene terephthalate/polystyrene‐block–polycaprolactone blends: Emulsification and mechanical performance
Authors: Mckay Ian D. 
Published: April 2003

AbstractA polystyrene‐polycaprolactone diblock copolymer was extrusion blended with polystyrene and polyethylene terephthalate. The morphologies of the resultant blends were studied using differential scanning calorimetry and scanning electron microscopy. In all compositions studied, the polystyrene and polyethylene terephthalate phases exhibited discrete glass transitions indicative of the immiscibility of these components. However, addition of the copolymer increased the extent of dispersion of the homopolymer components within one another quite effectively. Blend specimens were tested with respect to tensile, flexural, impact, and thermal performance characteristics to study the effects of morphology and composition on these factors. In general, the blends were rigid, brittle materials with some‐what enhanced thermal characteristics. Addition of polystyrene‐block‐polycaprolactone polymer to the blends resulted in increased brittleness, slightly reduced thermal performance, and, in some instances, greatly increased rigidity.
Unsaturated polyesters, III. Polyester from maleic anhydride and 1,4‐butylene glycol
Authors: Larez V. Cristobal J. , Mendoza Gilberto A. Perdomo 
Published: April 2003

AbstractThe polyesterification reaction of maleic anhydride and 1,4‐butylene glycol was carried out, using p‐toluensulphonic acid as catalyst. The resulting material was characterized by IR and H1‐NMR spectroscopy, end group analysis, and gel permeation chromatography. It is shown that there is a relationship between maleate to fumarate isomerization and steric interaction among condensed groups on the one hand and the tendency of the reacting system to crosslink or gel.
Effect of cholesteryl additive on poly(ethyl methacrylated)–poly(vinyl acetate) blend
Authors: Deshpande Dinkar D. , Basu Chandana , Panday Madhav 
Published: April 2003

AbstractThree different compositions (9 : 1, 7 : 3, and 1 : 1) of poly(ethyl methacrylate) (PEMA) and poly(vinyl acetate) (PVAc) are chosen to check the miscibility of a polymer pair. The 9 : 1 and 7 : 3 PEMA‐PVAc blends are immiscible and have shown two distinct loss peaks in dynamic mechanical analysis (DMA) studies, while 1 : 1 PEMA‐PVAc has shown a single loss peak. Immiscible composition 7 : 3 PEMA‐PVAc is selected to study the effect of cholesteryl additives on the miscibility of the polymers. The additives chosen for the present studies are cholesteryl chloride, cholesteryl caprylate, and cholesteryl laurate. The DMA studies showed that all the additives caused a merging of the two loss peaks into one. X‐ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) studies of the blend and blend with additive samples are utilized to get further information. The FTIR studies do not show any detectable change. The SEM micrographs of the blend and cholesteryl additive systems show a single‐phase ordered structure, and XRD data studies indicate the presence of small crystallites.
Catalyst effects found in thermal and mass spectrometric analyses of polycarboxylic acids used as durable press reactants for cotton
Authors: Trask‐Morrell Brenda J. , Andrews B. A. Kottes , Graves E. E. 
Published: April 2003

AbstractEffective polycarboxylic acids (PCAs) crosslink cotton cellulose by an ester linkage and smooth‐drying fabrics are produced. The presence of a catalyst improves the crosslinking reaction. A series of seven PCAs was examined by thermal analytical (TA) and mass spectrometric (MS) techniques. The focus of this research was to discover if catalyst effects were measurable by TA and MS and to seek additional support for a proposed mechanism of cellulose/organic acid reactivity via acid anhydride formation. Thermal analyses consisted of differential scanning calorimetric (DSC) and thermogravimetric (TG) procedures. MS analyses, using the electron impact mode, were performed by direct probe sample insertion. Observed catalyst effects included shifts in peak positions to lower temperature/time, and were noticeable primarily in MS‐reconstructed ion current chromatograms and DSC thermograms. Two TG parameters, the amount of residue produced and the rates of weight loss, offer ways to predict the effectiveness of a PCA with respect to smooth‐drying character. The presence of the catalyst influenced both measurements in desirable directions. Finally, the catalyst did not alter TG water loss data that support the proposed mechanism of reaction with cellulose via an anhydride intermediate.
Vulcanization of rubber. Kinetic parameters for SBR and simulations of vulcanization in a mold
Authors: Jönsson Kersti , Flodin Per 
Published: April 2003

AbstractDifferential scanning caiorimetry (DSC) was used to characterize the vulcanization of styrene‐butadiene rubber (SBR). The effect of three different fillers on the vulcanization process was also investigated. The fillers used were carbon black HAF and SRF and silica. The calculated reaction orders, activation energy, reaction energy, and preexponential factor, completed with physical properties, were used to calculate the temperature and extent of reaction inside a mold with time. The mathematical model used yields that are in fair agreement with experimental temperature measurements inside the mold.
Preparation and characterization of maleimide‐terminated poly(arylene ether sulfone) oligomers of various molecular weights
Authors: Jin Shijiu , Yee Albert F. 
Published: April 2003

AbstractA new variation in the bismaleimide (BMI) resin family, maleimide‐terminated poly(oxy‐1,4‐phenylene sulfonyl‐1,4‐phenylene) oligomers, has been synthesized. The preparation of oligomers (n = 1–12) is described in this study. The structure of these oligomers is characterized by FT‐IR and NMR spectroscopy. These oligomers are light yellow to light gray powders that can be melted or dissolved in solvents. Their terminating group bismaleimide has relatively high reactivity. Therefore, these BMI resins can be cured at 250°C to form a crosslinked product. Since the backbone chain is poly(arylene ether sulfone), the cured polymers have high Tg's, which increased from 220°C to higher than 340°C as the number of repeating units n of the corresponding oligomers decreases.
Separation of liquid mixtures by using polymer membranes. I. Water–alcohol separation by pervaporation through PVA‐g‐MMA/MA membrane
Authors: Chiang Wen‐Yen , Hu Chun‐Min 
Published: April 2003

AbstractA membrane was designed for the separation of a water–alcohol mixture by pervaporation on the basis of the difference in hydrogen‐bonding interaction between two components of the membrane. Two kinds of poly(vinyl alcohol)‐g‐maleic anhydride/methyl methacrylate membrane were prepared by different methods: (1) A homogeneous membrane was formed by casting from dimethyl sulfoxide solution after purification. (2) A porous membrane was obtained directly by casting from the reaction solution, and then was purified. It is found that water was permeated through a homogeneous membrane preferentially in all ranges of feed compositions. Moreover, the flux was found to decrease with increasing PVA content in the membrane. The porous membrane after heat treatment has selective permeability for methanol. Pervaporation of water was investigated with respect to the feed concentration and also to the operating conditions. The effect of the molecular size of the permeating species on both permeation and separation is also discussed.
The mechanism for occurrence of internal stress during curing epoxide resins
Authors: Ochi Mitsukazu , Yamashita Kiichi , Shimbo Masaki 
Published: April 2003

AbstractThe mechanism for the occurrence of internal stress in the curing cycle of four‐functional epoxide resins was investigated in detail. The internal stress in this system was generated at the vitrification point in the course of curing, because the modulus of samples was rapidly increased at this point. After the vitrification point, the internal stress was increased with an increase of the shrinkage in the curing and cooling processes.Moreover, the magnitude of the internal stress in the four‐functional resin systems depended on the chemical structure of aromatic diamines used as curing agents. This was explained by the difference of curing shrinkage after vitrification in each system.
Crystallization behavior of polypropylene filled with surface‐modified calcium carbonate
Authors: Mitsuishi Kazuta , Ueno Satoru , Kodama Souji , Kawasaki Hitoshi 
Published: April 2003

AbstractPolypropylene (PP) and calcium carbonate (CaCO3) were mixed in a two‐roll mill. The mixed compounds were molded on the plate by using a compression press heater. To improve the affinity of the relation between CaCO3 and the PP matrix, we modified the CaCO3 surface through chemical reaction with alkyl dihydrogen phosphates. The CaCO3 content and size modification affected the crystallization behavior of the filled PP composites. The crystallization temperature in the nonisothermal crystallization process increased with the increase of CaCO3 content and the decrease of CaCO3 size. The crystallization temperature revealed the function of log (1 + Ts) (Ts, total surface area of CaCO3) irrespective of CaCO3 content and size for modified and unmodified systems, respectively. The shoulder or double crystallization peak of PP composites is recognized for the unmodified system (particle sizes: 1.0 and 4.5 μm).
Polymer aqueous solutions as quenching media. II. Ethylene oxide–propylene oxide copolymers
Authors: Louai Abderrahim , Pollet Gilbert , Francois Jeanne , Moreaux Francois 
Published: April 2003

AbstractThe cooling power of aqueous solutions of ethylene oxide‐propylene oxide copolymers are studied with a silver standard sample by using two apparatuses quench with injection and quench with agitation. For temperature T>400°C, the viscosity plays the predominant role; for T<400°C, the cooling is controlled by the polymer precipitation and the cooling rate decreases by lowering the cloud point of the polymer solution. This work demonstrates the possibility of adjusting the cooling curves by taking into account the thermodynamical properties of the polymer.
Synthesis and rheological properties in aqueous solution of poly(acrylamide‐co‐sodium allylsulfonate)
Authors: Kejun Yao , Guowei Zhuo 
Published: April 2003

AbstractThe copolymerization of acrylamide (AM) with sodium allylsulfonate (SAS) was studied. The copolymerization rate equation was determined, Rp = K[KPS]0.70[AM]1.60[SAS]−0.60. The copolymeric composition obtained by nitrogen and sulfur elemental analysis, and 1H‐NMR method. The reactivity ratios were calculated by the Kelen–Tudos method and the value of r1(AM), r2(SAS) was determined to be 2.45 and 0.060, respectively. The rheology of aqueous solution of synthetic poly(acrylamide‐co‐sodium allylsulfonate) was determined at different temperatures and flowing activation energy Eη were calculated.
Thermal behavior and cured products of fluorine‐containing bismaleimides
Authors: Nagai Akira , Takahashi Akio , Suzuki Masahiro , Mukoh Akio 
Published: April 2003

AbstractThermal behavior of fluorine‐containing bismaleimides was investigated by differential scanning calorimetry and the effects of introducing fluorine groups on thermal behavior and properties of cured products were discussed. The melting point was lower and the polymerization temperature was higher with increasing fluorine content. This decrease in polymerization reactity of fluorine‐containing bismaleimide was explained by the stabilization energy of the double bond or the bismaleimide molecule itself as calculated by the MNDO or MM method. Thermal polymerization of the double bond was interpreted by an autocatalytic reaction mechanism in which the activated biradical product accelerated the radical propagation. It was found that the fluorine‐containing cured product had good thermal stability and a low dielectric constant.
Miscibility of poly(methoxymethyl methacrylate) and poly(methylthiomethyl methacrylate) with poly(styrene‐co‐acrylonitrile) and poly(p‐methylstyrene‐co‐acrylonitrile)
Authors: Goh S. H. , Lee S. Y. , Leong C. L. 
Published: April 2003

AbstractThe miscibility of poly(methoxymethyl methacrylate) (PMOMA) and poly(methylthiomethyl methacrylate) (PMTMA) with poly(styrene‐co‐acrylonitrile) (SAN) and poly(p‐methylstyrene‐co‐acrylonitrile) (pMSAN) was studied by differential scanning calorimetry. PMOMA is miscible with SAN having an acrylonitrile (AN) content around 30 wt %. However, PMOMA is immiscible with any of the pMSAN having AN contents between 9 and 36 wt % and with pMSAN having AN contents between 19 and 34 wt %. The miscibility of the blends enables the evaluation of various segmental interaction parameters.
Miscibility behaviour of bisphenol‐A polycarbonate and poly(para‐chlorostyrene)
Authors: Krings L. H. M. , Buning G. H. Werumeus , Nies E. 
Published: April 2003

AbstractThe miscibility behaviour of bisphenol‐A polycarbonate (PC) and poly(para‐chlorostyrene) (PpCIS) has been investigated. Special attention has been paid to the influence of the molar mass of PpCIS. Molar masses varying from 10 to > 1,000 kg/mol were used. The blends were studied by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and scanning and transmission electron microscopy (SEM and TEM). It was concluded that the blends of all three PpCIS grades and PC phase separate. In the low concentration region, some intermixing was found, especially for the blend with the low molar mass PpCIS. The most important effect of lowering the molar mass of PpCIS was an acceleration of the phase separation. The combination of SEM with electron probe X‐ray microanalysis (EPMA) gave qualitative information on the miscibility behaviour and was found to be a useful extension of routine microscopy techniques used in blend studies.
The effect of annealing on the thermal and dynamic mechanical properties of para‐tetramethyl xylene diisocyanate‐based polyurethanes
Authors: Stack G. M. , Beumel L. L. 
Published: April 2003

AbstractA series of polyurethane elastomers based on the para‐Tetramethyl Xylene diisocyanate group were annealed at temperatures from 100 to 180°C. These high‐temperature exposures were found to raise significantly the peak melting point of the urethanes that contained crystalline hard segments. The corresponding enthalpy of fusion was found to decrease after annealing at the higher temperatures. In most cases, the annealings caused a slight increase in the soft‐segment glass transition temperature, indicating that some increase in phase mixing had occured. Dynamic mechanical measurements indicated that the annealings caused a slight reduction in the Young's modulus and a broadening of the loss–tangent peak. The broadening of the loss–tangent peak can be attributed to the increased phase mixing induced by the annealings. The large increases in melting point induced by annealing do not appear to significantly affect the subsequent dynamic mechanical properties.
Characterization of linear low density polyethylene by temperature rising elution fractionation and by differential scanning calorimetry
Authors: Karbashewski Elizabeth , Kale L. , Rudin A. , Tchir W. J. , Cook D. G. , Pronovost J. O. 
Published: April 2003

AbstractIn this article we consider characterization of the branching distribution of LLDPE by analytical TREF and by DSC techniques. Qualitatively, both methods yield parallel information, provided that the DSC samples are prepared at very slow cooling rates. Analytical TREF provides more quantitative information, however, in that the mass fraction of material with different branch levels can be estimated. Full characterization of a polyethylene requires the use of a preparative TREF technique, in which fractions dissolved at preselected temperatures are investigated for branching with high resolution 13C NMR and for molecular weight distribution, with high temperature SEC analyses.
Transport properties in polypyrrole–PVA composites: Evidence for hopping conduction
Authors: Makhlouki Mohamed , Morsli Mustapha , Bonnet Alain , Conan Alain , Pron Adam , Lefrant Serge 
Published: April 2003

AbstractExperimental results on electrical conductivity and thermoelectric power for FeCl3‐doped polyvinyl alcohol‐polypyrrole composites, with polypyrrole content exceeding the percolation threshold, are presented. The electrical conductivity is analyzed in terms of the hopping theory, whereas the thermoelectric power displays a metallic‐like dependence. A model involving both the intrinsic resistance of the fibrils (V.R.H. hopping mechanisms) and the resistance of the junctions between fibrils (fluctuations‐induced tunneling conduction) has been retained.
Novel effect of barbituric acid on glass transition temperature of bismaleimide–epoxy resin systems
Authors: Pan Jing‐Pin , Shiau Gwo‐Yuh , Chen Ker‐Ming 
Published: April 2003

AbstractBarbituric acid (BTA) has a novel influence on glass transition temperature (Tg) of bismaleimide (BMI)–epoxy resin systems. It causes the Tg of a BMI–epoxy resin system to rise significantly. The BTA's influence on Tg was investigated by changing the molar ratio of the reactants. In addition, the influence of benzoperoxide (BPO) on Tg was compared with that of BTA. The reaction selectivity of BTA and diamino‐diphenyl sulfone (DDS) toward BMI and epoxy individually in the BMI–epoxy blended systems were studied using the DSC and GPC. By controlling the amount of DDS and BTA, epoxy and BMI could form intercrosslinking networks.
Hydrophilic elastomer containing poly(tetrahydrofuran) segments and viologen units
Authors: Kohjiya Shinzo , Hashimoto Tamotsu , Yamashita Shinzo 
Published: April 2003

AbstractElastomeric polymer consisting of poly(oxytetramethylene) segments and viologen units was prepared by living cationic polymerization of tetrahydrofuran (THF), followed by the end capping of the living polymer by 4,4´‐bipyridine. The obtained ionene‐type polymer (PTV) exhibited low tensile modulus and high tensile strength with large extensibility, i.e., it is an excellent elastomer from its mechanical properties. The water swelling behavior and effects of water and the sort of counter anions on the tensile properties of PTV were investigated. PTV showed high hydrophilicity; e.g., the water content of PTV with bromide counter anions was ca. 40% after swelling in water at 25°C for 24 h. However, even for the samples with such a high water content, PTVs displayed good elastomeric properties, although the tensile modulus and tensile strength were decreased with increase of water content. The hydrophilicity of PTV was found to depend on the kind of counter anions, which in turn determined the tensile properties of PTVs in a swollen state.
Molecular mobility in wool fibers as determined from nuclear magnetic resonance studies
Authors: Rao D. Rama , Gupta V. B. 
Published: April 2003

AbstractThe mobility of protons in wool samples of Lincoln, Chokla, and Merino, equilibrated to various moisture contents in the range of 0–98% relative humidity (RH), have been studied by pulsed nuclear magnetic resonance (NMR) technique. Peak height and peak width were determined from absorption and derivative curves and the relaxation times T1 and T2 were determined from relaxation curves. The mobility increases with increase in moisture content. Among the three wools, the mobility was high in Merino as compared to the other two wools. The differences in the measured mobilities were related to structural and morphological differences in the three wools. The present analysis suggests that water in wool has at least three different associations, each with a different binding energy.
New class of cellulose fiber spun from the novel solution of cellulose by wet spinning method
Authors: Yamashiki Takashi , Matsui Toshihiko , Kowsaka Keisuke , Saitoh Masayoshi , Okajima Kunihiko , Kamide Kenji 
Published: April 2003

AbstractA novel cellulose solution, prepared by dissolving an alkali‐soluble cellulose, which was obtained by the steam explosion treatment on almost pure natural cellulose (soft wood pulp), into the aqueous sodium hydroxide solution with specific concentration (9.1 wt %) was employed for the first time to prepare a new class of multifilament‐type cellulose fiber. For this purpose a wet spinning system with acid coagulation bath was applied. The mechanical properties and structural characteristics of the resulting cellulose fibers were compared with those of regenerated cellulose fibers such as viscose rayon and cuprammonium rayon commercially available. X‐ray analysis shows that the new cellulose fiber is crystallographically cellulose II, and its crystallinity is higher but its crystalline orientation is slightly lower than those of other commercial regenerated fibers. The degree of breakdown of intramolecular hydrogen bond at C3[Xam(C3)] of the cellulose fiber, as determined by solid‐state cross‐polarization magic‐angle sample spinning (CP/MAS) 13C NMR, is much lower than other, and the NMR spectra of its dry and wet state were significantly different from each other, indicating that cellulose molecules in the new cellulose fiber are quite mobile when wet. This phenomenon has not been reported for so‐called regenerated cellulose fibers.