bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and some properties of PVC‐bound dimethylglyoxime complexes of Co(II), Ni(II), and Cu(II)
Authors: Biswas Mukul , Moitra Subrata 
Published: April 2003

AbstractPoly(vinyl chloride) (PVC) has been reacted with dimethylglyoxime (DMG) in THF to form the PVC–DMG comples, which has been characterized by spectroscopic and elemental analyses. The latter indicate that there is one DMG moiety anchored on the PVC chain by displacing every 12th Cl atom in the chain. PVC–DMG has further been reacted with alcoholic solutions of Co(II), Ni(II), and Cu(II) to form the intensely colored PVC–DMG–M(II) complexes. The structures of these complexes have been analyzed by elemental and IR spectral analyses. The overall thermal stability of PVC–DMG–M(II) increases in the order: PVC < PVC–DMG–Cu(II) < PVC–DMG–Ni(II) < PVC–DMG–Co(II). The electrical conductivities are also significantly enhanced in the same order. The permittivities of these complexes are high relative to PVC at low frequency falling gradually with increasing frequency and the dielectric loss‐frequency behavior is very broad.
DSC and13C‐NMR studies of the imidazole‐accelerated reaction between epoxides and phenols
Authors: Hale Arturo , Macosko Christopher W. , Bair Harvey E. 
Published: April 2003

AbstractThe imidazole‐accelerated reaction between epoxides and phenols has been studied through DSC and13C‐NMR of model compounds. The selectivity of the accelerator has been found to be strongly dependent on its concentration. If a low amount of accelerator is used, the reaction takes place almost exclusively through the addition of phenols to epoxides even if the latter are used in excess. However, a larger amount of accelerator will cause the secondary hydroxyls (produced by the main reaction) to react with the epoxides. In any case, the lower reactivity of the secondary hydroxyls prevents them from reacting to any significant extent as long as there are any phenols present. When polyfunctional resins are used, the effect of the selectivity of the reaction on the properties of the crosslinked network is very clear. If a low amount of accelerator is used (to promote only the epoxy–phenol reaction), the maximum glass transition temperature (Tg) occurs when the epoxides and phenols are stoichiometrically balanced, reaching 178°C. However, when an excess of epoxides over phenols is used, along with a larger amount of accelarator, the maximumTgincreases its value to 199°C.
Structure and viscoelastic properties of epoxy resins prepared from o‐cresol novolacs
Authors: Hasegawa Kiichi , Fukuda Akinori , Tonogali Saburo , Uede Kazuo 
Published: April 2003

AbstractThe relation between the structure and viscoelastic properties of the epoxy resins prepared from o‐cresol novolacs was studied. Our model epoxy resins were two kinds of epoxy compounds synthesized from three‐nuclei and four‐nuclei o‐cresol novolacs. In addition to these models, a commercially available o‐cresol novolac‐type epoxy resin was also studied. Each of the three epoxy compounds was cured with one of three kinds of novolacs, which were starting materials of the above‐mentioned epoxy resins. Characteristic properties of the cured resins, such as glass transition temperature (Tg), average molecular weight between crosslinking points (M¯c), and front factor (ϕ) were obtained. It was concluded that the number of functional groups contained in the curing system almost dominated the viscoelastic properties of the cured resins.
Synthesis of copolymers of N,N‐dimethyl acrylamide and methacrylate esters and their surface tensions
Authors: Weinert Raymond J. , Piirma I. 
Published: April 2003

AbstractA systematic study was made on the preparation of N,N‐dimethylacrylamide (NDMA)/ methacrylic ester statistical copolymers. The methacrylic ester comonomers used in the copolymerizations were ethyl, n‐butyl, n‐hexyl, n‐octyl, n‐dodecyl, n‐hexadecyl, and n‐octadecyl methacrylates. It was found that the NDMA copolymers could be prepared in three molecular weight regions: 1.0 × 104, 2.0 × 105, and greater than 1.0 × 106 ([η] in water at 30°C of 0.1, 0.6, and greater than 1.5 dL/g, respectively). The molecular weights of the copolymers were dependent on the solvent employed in the polymerizations and on the presence of a chain transfer agent (t‐dodecyl mercaptan). All copolymer compositional analyses were made by 400 MHz 1H‐NMR spectroscopy. The NDMA/methacrylic ester copolymers decreased the surface tension of water in the order: C4 = C6 > C8 > C12 > C16 > C2 = C18 > P(NDMA), lowest surface tension (35 dyn/cm) to highest surface tension (59 dyn/cm).
Gradient high‐performance liquid chromatography of statistical and block copolymers of styrene and t‐butyl methacrylate
Authors: Glöckner Gottfried , Müller Axel H. E. 
Published: April 2003

AbstractCopolymers of styrene (S) and tert‐butyl methacrylate (TBMA) containing 24–92 mass % of the latter monomer were investigated using a silica column with isooctane/tetrahydrofuran (THF) gradients and on a phenyl bonded‐phase column by methanol (MeOH)/THF gradients using UV detection. In both cases, retention decreased with increasing TBMA content of the sample. This is in contrast to the behavior of copolymers of S and methyl methacrylate (MMA) whose retention in gradient elution on silica columns increases with MMA content due to the polarity of this unit. The inversion of elution order is a result of the bulky TBMA residues shielding the polar groups of the ester units. For copolymers of varying composition, the gradation in retention on retention on silica is quite sufficient for separating S/MMA but not for S/TBMA mixtures. The latter could be separated by composition on phenyl packings through MeOH/THF gradient elution. Block copolymers containing 80 or 92% TBMA could be baseline‐separated. It was also possible to separate these samples from admixed PTBMA or PS homopolymers. Under the conditions used, the retention of a given block copolymer was somewhat higher than that of a statistical copolymer having the same composition. A block copolymer containing 80% TBMA was converted by transesterification into a S/MMA block copolymer. The elution of the latter fitted well in the sequence of S/MMA copolymers on silica column.
Electrochemical preparation of electrically conducting polyurethane/polyaniline composite
Authors: Pei Qibing , Bi Xiantong 
Published: April 2003

AbstractComposite films from polyaniline (PANi) and polyurethane (PU), with flexibility and mechanical strength similar to pure PU and conductivity close to pure PANi, have been obtained by electropolymerizing amiline on a PU/Pt electrode in water/acetonitrile/ethylen glycol electrolyte solution. In the composite films, PANi is dispersed, in the form of particulate, inside and on the inner surface of the PU substrates. It is found that the electropolymerization reaction of aniline proceeds much faster in basic solution and composite film as prepared shows higher conductivity than that in acidic solution. PANi in PU/PANi composite film is protonic‐acid‐doped and is conducting even in case it is electropolymerized in a basic electrolyte solution.
Adhesion of photocurable acrylates to solid polymer substrates
Authors: Jönsson S. , Gölander C. G. , Biverstedt A. , Göthe S. , Stenius P. 
Published: April 2003

AbstractThe adhesion of a hydrophilic (surface tension γ ≈ 40 mj/m2) and a hydrophobic (γ ≈ 30 mj/m2) photopolymerized acrylate lacuer a low‐density polyethylene, polystyrene, polycarbonate, polymide‐6‐6, polyvinylchloride, polyethyleneterephthalate, poly‐(1,1)‐difluoroethylene, and polymethylmetacrylate has been investigated. A primary condition to obtain sufficient adhesion, as probed by the Scotch tape test, is that the surface tension of the lecquer has to be lower than the critical surface tension of the lacquer. There is no obvious correlation with possible doner/acceptor interactions between lacquer and substrate. Even when spreading occurs, other factors may cause insufficient adhesion. On polyamide, residual moisture on the surface is vary detrimental to adhesion. Extending the lag‐time between application and curin reduced adhesion, in particular to polymers containing aromatic groups. This appears to be due to inhibition of the polymerization reaction by radiation‐adsorbing aromatic groups in the swollen interphase. The effect can be avoided by proper choicd of initiator and radiation‐adsorbing aromatic groups in the swollen interphase. The effect can be avoided by proper choice of initiator and radiation source. Curing of the lacquers in a nitrogen atmosphere generally results in poor adhesion because the rate of polymerization/curing becomes very high compared with rats of relaxation of stresses in the lacquer.
Elastomeric polyurethanes reinforced with aramid fibers
Authors: Andreopoulos A. G. , Konstantinidou A. V. , Petsalas H. J. 
Published: April 2003

AbstractThermolplastic polyurethane is a relatively new development in the elastomers field, combining elastomeric behavior with thermoplastic processing characteristics. Thus, high production rate and reduced scrap can be achieved but, increased versatility for the incorporation of additives is also possible. In this work, thermoplastic polyurethane matrices were prepared and Kevlar pulp was dispersed as a reinforcing agent. Since good dispersion and appropriate filler volume fraction are critical factors for a reinforcing effect, special attention was paid to the optimization of these parameters. Thermoplastic polyurethanes were prepared by mixing a low melting polyol with a low melting diisocryanate and the subsequent addition of small amounts of a chain extender, namely, a low molecular weight diol such as 1,4 butanediol. The Kevlar pulp was added under stirring either in the polyol or the diisocyanate melt. This incorporation technique allows the disperision of small fiber percentages. Thus, calendering of the materials prepared was also performed and additional fibers were incorporated. Changes in the properties of properties of the specimens prepared as a function of the filler volume fraction and the dispersion technique were determined, taking into consideration the possibilities of chemical interaction between fibers and matrix.
Annealing studies on a fully cured epoxy resin: Effect of thermal prehistory, and time and temperature of physical annealing
Authors: Pang K. P. , Gillham J. K. 
Published: April 2003

AbstractThe dynamic mechanical behavior at about 1 Hz of a fully cured epoxy resin (maximum glass transition temperature, Tg∞, ca. 170°C) ahs been studied during and after isothermal annealing in terms of the influence of thermal prehistory, time of annealing, and temperature of annealing (Ta). Annealing temperatures ranged from Tg − 15 to Tg − 130°C. The rate of isothermal annealing was observed to decrease by a decade for each decade increase of annelaing time when the material was far from equilibrium. Annealing at high temperatures did not measurably affect the mateiral properties during cooling (for T ≪ Ta); similarly the effect of annealing at low temperatures was not measurale during heating (for T ≫ Ta).
Graft copolymer of gelatin/butyl acrylate and its use in the dye transferring blank film
Authors: Li Zhi‐Chong , Fu Zhi‐Feng , Huang Ming‐Zhi , Miao Jin‐Kang , Lian Na 
Published: April 2003

AbstractButyl acrylate was graft copolymerized onto gelatin using ceric ammonium nitrate as redox initiator. A series of grafted products with various gelatin‐to‐butyl acrylate ratios were prepared. The molecular weight of the grafted side chains and the number of grafting sites were measured. The possible grafting sites on gelatin macromolecules were pointed out through amino acid analysis. The electron micrograph and DSC analysis showed that the grafted chain (PBA) and backbone gelatin were in separated phases. The graft copolymer was used in the receiving layer of the dye transfer blank film, and the photographic, dye transfer printing, and some physicomechanical properties were studied with satisfactory results.
Polymerization of surface‐active monomers. III. Polymer encapsulation of silica gel particles by aqueous polymerization of quaternary salt of dimethylaminoethyl methacrylate with lauryl bromide
Authors: Nagai Katsutoshi , Ohishi Yoshiyuki , Ishiyama Kadzuo , Kuramoto Noriyuki 
Published: April 2003

AbstractPolymer encapsulation of silica gel particles (SiO2) by aqueous, radical polymerization of a cationic, surface‐active monomer, quaternary salt of dimethylaminoethyl methacrylate with lauryl bromide, in the presence of the solid was investigated. The polymerization gave the polymer encapsulating the solid particles (“C‐polymer”), though accompanied by the formation of that suspended in form of latex (“L‐polymer”). The proportion of C‐polymer in the products increased with increasing the amount of SiO2 at a constant monomer concentration and only C‐polymer was formed under the conditions where the feed ratio of monomer to SiO2 is about 0.13 or lower by weight. Increasing the monomer concentration in feed increased slightly the ratio of C‐polymer to SiO2. The results obtained here suggest that C‐polymer is mainly formed through the polymerization of monomer adsorbed on the solid surface. An electron micrograph of the polymer‐encapsulated SiO2 revealed that the solid particles are uniformly encapsulated with the resulting polymer.
Effect of E/P ratio on the rheology and morphology of crosslinkable polyethylene and EPDM blends
Authors: Mukhopadhyay P. , Das C. K. 
Published: April 2003

AbstractEffects of E/P ratio of the EPDM rubber on the flow behavior and morphology of the crosslinkable polyethylene and EPDM blends have been studied as a function of shear rate and processing temperature. High‐E/P‐ratio EPDM rubber exhibits high viscosities within the temperature range studied but the extrudate swell is higher for the low E/P ratio EPDM. Shear modulus, stored elastic energy and flow activation energy are higher for high E/P ratio EPDM but relaxation time is higher for low E/P ratio EPDM. At a particular blend ratio these rheological parameters show a change in their pattern. This point of change in pattern occurs at a lower level of EPDM having a high E/P ratio; this suggests an early phase inversion as corroborated by the SEM studies. Melt fracture occurs to a larger extent for the low E/P ratio EPDM in its blends with XLPE.
Modified phenol–formaldehyde novolac resins: Synthesis and thermal oxidative degradation
Authors: Tuǧtepe M. , Özgümüş S. 
Published: April 2003

AbstractNew phenolic resins containing titanium and silicon in the main polymer structure were synthesized and some of their properties were investigated. Titanium and silicon contents of the polymers ranged from 2 to 13% titanium and from 2 to 5% silicon. These polymers became insoluble and infusible as the titanium and silicon contents of the products were increased. IR spectra of these modified resins were presented. The thermal oxidative degradations of the phenolic resins modified with titanium and silicon were also investigated using thermogravimetry and differential thermal analysis. Titanium and silicon‐modified polymers, showed considerably lower weight changes as compared with those of unmodified or titanium‐modified polymers, but the rate of the last oxidative degradation increased and the final degradation temperature decreased with increasing titanium concentration. The best results for the thermal resistance was found to be 2% ≤ Ti ≤ 6% and Si 2–5%.
Isothiocyanato‐substituted hydrophilic polymer beads for immobilization of enzymes
Authors: Kitano Hiromi , Hasegawa Masanori , Kaku Takashi , Ise Norio 
Published: April 2003

AbstractStyrene–glycidylmethacrylate–divinylbenzene resin beads could be converted to highly hydrophilic resin beads by acid treatment. These resin beads could be modified with isothiocyanato (NCS) groups quite easily using a Friedel–Crafts reaction and a subsequent nucleophilic reaction with KSCN. The resin beads substituted with NCS groups were useful as supports to immobilize enzymes, because they were not only hydrophilic but also bind proteins covalently. The enzymes immobilized onto the resin beads showed sufficiently high catalytic activities for a long period.
Stretching of PET films under constant load. II. Structural analysis
Authors: Le Bourvellec G. , Beautemps J. 
Published: April 2003

AbstractThe structure development of a PET film is studied during drawings under constant load. The evolution of crystallinity, amorphous orientation, and axial and planar birefringences is described along a deformation path. The influence of the stretching force and stretching temperature is also analysed.
A crack layer approach to fatigue crack propagation in high density polyethylene
Authors: Kasakevich M. L. , Moet A. , Chudnovsky A. 
Published: April 2003

AbstractFatigue crack propagation (FCP) in high density polyethylene (HDPE) is observed to occur with an accompanying layer of damage ahead of the crack tip. The crack layer theory, which accounts for the presence of both the damage and the main crack, is applied to the problem. It is observed that the kinetic behavior of HDPE under fatigue consists of three regions: initial acceleration, constant crack speed (“deceleration”), and reacceleration to failure. Within the first two regions, crack propagation appears “brittle,” while in the third region “ductile” behavior is manifested. Ultimate failure occurs via massive yielding of the unbroken ligament. Two damage mechanisms are found to be responsible for HDPE failure: formation of fibrillated voids and yielding. Both mechanisms are present throughout the entire lifetime of the crack, but the former dominates the “brittle” crack propagation region, while the latter is more prominent in the “ductile.” Throughout the analysis the resistance moment Rt is approximated as the total volume of transformed material associated with crack advance. Crack layer analysis produces a satisfactory fit of the experimental data and yields a specific enthalpy of damage, γ*, value in the 1–2 cal/g range.
Studies on binary and ternary blends of polypropylene with ABS and LDPE. II. Impact and tensile properties
Authors: Gupta A. K. , Jain A. K. , Ratnam B. K. , Maiti S. N. 
Published: April 2003

AbstractStudies on impact and tensile properties of binary blend of PP and ABS and ternary blend of PP, ABS, and LDPE are presented. Variation of impact strength and the fracture surface morphology with blend composition is examined and interpreted. Tensile behavior in the yield region is studied and the trends of variation of work of yield and impact strength are compared to ascertain the predominent mechanism of impact toughening in these binary and ternary blends. An analysis of yield–stress data in terms of theoretical models is presented to reveal the differences in these binary and ternary blends, attributable to the role of LDPE component in the ternary blend.
Characterization of interfacial interactions in high density polyethylene filled with glass spheres using dynamic‐mechanical analysis
Authors: Kubát J. , Rigdahl M. , Welander M. 
Published: April 2003

AbstractThe dynamic‐mechanical properties of high density polyethylene filled with 20% by volume of untreated glass spheres or glass spheres treated with a silane‐based coupling agent were studied as a function of temperature and imposed tensile deformation. The coupling agent used is capable of providing covalent bonding between the polymeric matrix and the glass spheres. It is assumed that an interphase region is formed in the matrix around each filler particle with properties depending on the surface treatment of the filler, but different to that of the bulk matrix. It is shown how the mechanical loss factor can be used to characterize the properties of the interphase region and the degree of adhesion between the two phases, as affected by the surface treatment. We suggest that these kinds of measurements can be valuable when determining the effectiveness of various surface treatments of filler particles from a mechanical point of view.
Characterization of the polymer‐supported phase transfer catalyst
Authors: Chou Su‐Chu , Weng Hung‐Shan 
Published: April 2003

AbstractPolymer‐supported phase transfer catalysts, which were prepared by immobilizing tributylamine on chloromethylpolystyrene, were characterized by optical microscope, SEM, EPMA, and ESCA. Both optical photograph and electron micrograph showed that the exterior surface of polymer support became wrinkly after immobilization in dry condition. The surface of the triphase catalyst may become smooth after being swelled by solvent. From the ESCA analysis in a depth of about 100 Å, it was found that 46.5% of covalent chloride in chloromethylpolystyrene had reacted with tributylamine and converted to quaternary ammonium chloride. However, the EPMA, which analyzed in a depth of about 1 μm, gave a value of only 31% and the titration method which was for the whole bead gave 14.3%. These results reveal that the catalyst has a higher content of quarternary ammonium chloride in the outer shell. It is concluded that the high activity of this catalyst is due to the fact that it contains both hydrophobic and hydrophilic groups on the exterior surface, and more active species in the outer shell.
Binding of chrysophenine G by methyl cellulose and poly(vinyl alcohol)
Authors: Shibusawa Takao , Tanaka Akira , Yamaguchi Yutaka 
Published: April 2003

AbstractEquilibrium constants (nK) for the binding of Chrysophenine G by methyl cellulose (MC) and poly(vinyl alcohol) (PVA) were determined spectrophotometrically in the temperature range 15–40°C. The polymer chains of PVA extended by the dye binding but those of MC shrank slightly. The enthalpy change and the entropy change for the binding by MC were negative and positive, respectively, whereas those for the binding by PVA were both negative. When the dye was bound to the extended polymer chains, the contribution of the entropy term to the binding increased. The rate of the dye bindings was studied by means of the temperature jump method. For the dye binding to PVA, the whole relaxation process finished in a very rapid step. On the other hand, for dye binding to MC, the initial rapid step was followed by two successive slower steps; the relaxation times for the slower steps were independent of the polymer concentration. The results were interpreted in terms of the stiffness of polymer chain of MC; the conformational change of the stiff chains to accommodate the dye in stable states seems to be the rate determining step in each slow relaxation.
Fatigue behavior of acrylic interpenetrating polymer networks. II
Authors: Hur T. , Manson J. A. , Hertzberg R. W. , Sperling L. H. 
Published: April 2003

AbstractEnergy‐absorbing simultaneous interpenetrating networks (SINs) based in polyether‐type polyurethanes (PUs) and poly(methyl methacrylate) (PMMA) networks were prepared by a prepolymer procedure. The products are translucent and appear to have single and broad glass transitions, suggesting some degree of phase separation. The percent energy absorption determined from dynamic properties and pendulum impact tests, the resistance to fatigue crack growth and fracture toughness (K1c) all increase with polyurethane content. The fracture behavior changes from brittle to ductile failure with increasing PU. The fatigue fracture surfaces of the SINs show extensive stress whitening associated with cavitation around the polyurethane domains, and localized shear deformation rather than crazing.