bluuebunny/crossref_metadata_2025_split huggingface dataset:
“Surface‐photografting”: new applications to synthetic fibers
Authors: Rånby Bengt , Guo Feng Zhen 
Published: April 2003

Abstract“Surface‐photografting” with UV‐irradiation of polypropylene (PP) fiber and film and high‐strength polyethylene (HSPE) yarn has been made with acrylic acid (AA) and acrylamide (AM) as monomers and benzophenone (BP), 4‐chlorobenzophenone (4‐BCP) and hydroxylcyclohexylacetophenone (HHA) as photoinitiators using a new continuous method. The grafting reaction occurs in a thin liquid layer on the fiber or film substrate, which is presoaked in a solution containing initiator and monomer. After irradiation with a highpressure mercury lamp, HPM 15 (2 kW) from Philips, for 5–20 sec at about 50°C the fiber and film surface is completely covered with a 2–8 nm thick layer of grafted polymer, analyzed by electron spectroscopy for chemical analysis. The grafting efficiency is 70–80%, i.e. only 20–30% of the polymer is homopolymer which can be removed by extraction. The grafted layers are so thin that they cannot be analyzed as weight increase (<0.1% of fiber weight). Absolute values for the amount of grafted AA polymer is analyzed by microtitration of the COOH groups at the fiber surface. The results agree well with the relative ESCA values. Grafting of commercial PP yarn with AA increases the adsorption of Crystal Violet dye with a factor of about 6. Grafting the same yarn with AM increases the adhesion to epoxy resin by a factor of 3–4 without affecting the mechanical properties of the fiber more than a few percent. For comparison, strips of blown PP film (5 mm wide) are modified by “surface‐photografting” with AM. With increasing grafting, the contact angle for drops of distilled water decreases from 90° to 20°, indicating extensive wetting. The adhesion to epoxy resin increases from about 0.35 to 1.7 N/mm2, i.e. with a factor of about 5 when the film surface is completely covered. Other comparisons are made with grafting of commercial HSPE yarn. Grafting with AA increases the adsorption of Crystal Violet dye by a factor of about 6. Grafting with AM increases the adhesion to epoxy resin from 0.25 to 1.3 N/nm2, i.e. with a factor of 5. The bulk mechanical properties of the HSPE filaments are not affected by the grafting measured as tensile strength 2.7±0.1 GPa, elongation at break 4.8±0.3%, and Young's modulus 55±3 GPa, both before and after “surface‐photografting”.
Plastic deformation and performance of engineering polymer materials
Authors: Oleinik Eduard F. , Salamatina Olga B. , Rudnev Serge N. , Shenogin Serge V. 
Published: April 2003

AbstractThe plastic deformation mechanism operating in polymer glasses is analyzed. The whole process consists of two main stages: nucleation of special shear defects, called PSTs (plastic shear transformations), and their disappearance. The important feature of plastic deformation of glasses is the storage of a large amount of internal energy ΔUdef upon straining. Such energy storage is the critical issue for mechanical performance of polymeric material: if the amount of stored energy is high, the appearance of macroscopic failure is very probable while glassy materials collecting a small amount of stored deformation energy are quite ductile. It is proposed that the rate of disappearance of PSTs is a key factor in dissipation of stored deformation energy. A parameter describing the dissipation ability of material upon deformation is introduced.
Photochromic polymers: effects of structure and environment on photoresponsiveness
Authors: Ciardelli Francesco , Pieroni Osvaldo , Fissi Adriano , Altomare Angelina , Solaro Roberto , Tirelli Nicola 
Published: April 2003

AbstractIn this review paper the photoresponsiveness of photochromic macromolecules under different structural and environmental conditions is discussed with reference to results from the authors' laboratories. Polypeptides, in particular poly(L‐glutamic acid) and poly(L‐lysine), with spirobenzopyrane side chains show photoinduced conformational variations which are amplified by addition of organic acids or bases to hexafluoro‐2‐propanol (HFP) solutions. Thus combination of light and environment effects allows modulation of order–disorder conformational transitions.Such photoindiced conformational changes are not observed in the case of macromolecules with a hydrocarbon main chain and azobenzene or stilbene side chains, obtained by polymerization of acrylic monomers. However, even in these systems structural variations affect the dependence of optical properties on irradiation. Moreover, the combination of organic solvents and water shows that polymer solubility can be modulated by light.
Morphologies and electro‐optic properties of phenoxy/liquid crystal composite films
Authors: Kim Byung Kyu , Kim Seon Hee , Choi Chi Hoon 
Published: April 2003

AbstractMorphology and electro‐optic properties of composite films composed of phenoxy and nematic liquid crystal (LC) have been studied at a film composition of 40/60 (polymer/LC by weight). Effects of temperature, frequency and voltage of applied a. c. electric field on the transmittance and response time of the films were measured.
High temperature polymer blends: an overview of the literature
Authors: DeMeuse Mark T. 
Published: April 2003

AbstractA review of work which has been performed on high temperature polymer blends is presented. The discussion is divided into miscible and immiscible blends. It is pointed out that one problem with miscible polymer blends is that of processing in the miscible state. In the case of immiscible blends, particularly ones containing liquid crystal polymers, the issue of adhesion of the two phases is discussed. Finally, the need for better theoretical models for predicting miscibility in polymer blends is highlighted.
Thermal behavior of new polymer electrolytes
Authors: Fauteux D. , McCabe P. 
Published: April 2003

AbstractSolid polymer electrolytes (SPE) have been identified as a class of materials which could enable the fabrication of high energy density solid state lithium rechargeable batteries which could meet the performance requirements for advanced portable electronic and automotive applications. In order to achieve this goal, novel SPE systems having high ionic conductivity and good mechanical properties at or near ambient temperature must be developed. Novel lithium salts believed to be useful in realizing this objective have recently been proposed. The thermal behavior of SPE systems based on high molecular weight poly(ethylene oxide) (PEO) and on two novel salts, the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and the lithium tris(trifluoromethylsulfonyl)‐methanide (LiTSFM) is reported and compared with the thermal behavior of the high molecular weight PEO–lithium trifluoromethane sulfonate (LiTFLT) SPE system. Phase diagrams for the PEO–LiTFSI and PEO–LiTFSM SPE systems have been established and are discussed in terms of their impact on SPE‐based rechargeable lithium battery technologies. The use of a novel plasticizer in conjunction with the PEO–LiTFSI‐based SPE system is reported and it is shown how this modifies the thermal behavior of the PEO–LiTFSI SPE system.
Corrosion inhibition of zinc‐plated steel in 0.5, 1 and 1.5 M sulphuric acid by poly(ethylene glycol)
Authors: Oun Ahmed Mohammed 
Published: April 2003

AbstractThe effect of poly(ethylene glycol) (PEG) 4000 on the corrosion of zinc‐plated steel in H2SO4 has been investigated over a wide range of conditions. It was found that the corrosion rate depends upon exposure time. The rate of corrosion goes down rapidly to reach a low value, which is an almost constant value within 5 hr under most conditions. This trend was also found by Growock and Lopp for the inhibition of steel corrosion in HCl with 3‐phenyl‐2‐propyl‐1‐ol. Other workers have linked this slow fall‐off in the corrosion rate to film formation. The corrosion rate was found to decrease slowly with increasing PEG concentration, and to increase slowly with acid concentration for all conditions.The effect of temperature on corrosion rate was found to be similar to that of acid concentration. The corrosion rate decreased exponentially with poly(ethylene glycol) concentration. The percentage inhibition reached a value of 48.93 for a PEG concentration of 4 ppm: to double this, the concentration had to be increased to 40,000 ppm.Sulphuric acid titration against sodium hydroxide showed no change in acid concentration during the corrosion protection process, thus supporting the film protection theory
Multi‐electron oxidation of formaldehyde on a platinum electrode
Authors: Nakabayashi S. , Tamura K. , Uosaki K. 
Published: April 2003

AbstractThe time evolution of a self‐sustained potential oscillation under constant current oxidation of formaldehyde was observed on the rotating ring disk electrode assemble. Under the condition when the potential was controlled, the laser deflection voltammogram as well as the conventional cyclic voltammogram were measured. The mechanism of the multi‐electron oxidationof formaldhyde on a platinum electode is discussed.
One‐step multi‐electron transfer mechanism of polynuclear copper complexes for molecular conversions
Authors: Viersen Frits Jan , Wilson Jennifer C. , Challa Ger , Reedijk Jan 
Published: April 2003

AbstractThe oxidative coupling reaction of 2,6‐dimethylphenol may result in either a desired polymeric substance (i.e. the polyphenylene ether, PPE) or the undesired “dimeric” species diphenoquinone, DPQ. The relative amounts of each product depend on the experimental conditions and the used catalytic system.Usually copper amine compounds are used as a catalyst for the oxidative coupling reactions. They have the advantage of easy access and produce high yields of high molecular PPE; however, other metal coordination compounds, like those of Mn, may also be used as catalysts.The present paper focuses on mechanistic studies with various copper (aliphatic and aromatic) amine compounds as catalysts. Owing to the steric constraints of the amine ligands, dinuclear Cu(II) compounds, with small bridging anionic ligands, are easily formed. Such species are believed to be the catalyst precursors. Upon addition of a base (1:1 on copper) and excess phenol, phenolate ligands coordinate as bridging ligands to copper. After a two‐electron transfer reaction, the resulting phenoxonium ligand, which is a rather poor ligand, remains attached to the Cu(I), probably coordinating via its aromatic ring. Nucleophilic attack by a phenol to the phenoxonium ion at the 4‐position is likey to be most important to the coupling reaction. In the beginning of the reaction the undesired side product DPQ is also formed via a C–C coupling reaction. With copper(II) compounds containing imidazole‐type chelating ligands, good activity was obtained; in the case of pyrazole‐based and bridging S‐donor chelating ligands, that no or very weak activity was found.In a study of the mechanism of the propagation reaction the rate‐determining reaction was thought to be probably a one‐step, two‐electron transfer, during which the two Cu(II) ions in the dinuclear complex oxidize the phenolate to phenoxonium. After the phenoxium ion is formed the bonding with the (then) Cu(I) species is weakened and the reactions with phenolic end groups can take place. The effect of the amine ligands appears to be both steric and electronic. With certain ligands the reoxidationof the reduced catalyst is not possible.
Multi‐electron transfer reactions and exciton interactions in fibrous porphyrin and metalloporphyrin assemblies
Authors: Fuhrhop Jürgen‐Hinrich , Bindig Uwe , Rosengarten Bianca , Siggel Ulrich 
Published: April 2003

AbstractNon‐covalent porphyrin and metalloporphyrin fibers of bimolecular thinness in bulk aqueous media are compared with the well‐known H‐ and J‐aggregates of cyanines. The J‐aggregates of cyanines fluoresce and are useful as photographic sensitizers. The J‐aggregates of porphyrins show light‐induced charge separation and the corresponding metal complexes produce stable radical dimers. The distance between the metalloporphyrin centers is calculated from circular dichroism spectra to be 8 Å in the J‐aggregates and about 4 Å in the H‐aggregates. Multi‐electron reactions of the fibers in the ground and excited states can therefore occur in the fibrous porphyrin assemblies. In amphiphilic tetraphenylporphyrins (“octopus porphyrin”), on the other hand, the porphyrin–porphyrin distance is much larger and the fiber dissolves electron‐accepting compounds, e.g. quinones, which also allow for multiple charge separation within such a fiber.
Multi‐electron transfer in composite phthalocyanine thin films: structure and electrochromic properties
Authors: Tominaga Tsuyoshi , Toshima Naoki 
Published: April 2003

AbstractBoth sequentially deposited double‐layered and codeposited composite thin films were prepared by using two kinds of phthalocyanines. The structure and the electrochromic property of these thin films were compared with those of simple phthalocyanine films. The structures of the films were analyzed by scanning electron microscopy (SEM), X‐ray diffrction (XRD) and electron spin resonance (ESR) spectra. From the viewpoint of morphology and crystallinity, codeposited thin films have the same structure as the simple one, having sharp peaks at ca. 2θ=7.0° in the XRD pattern and narrow crystal grains in SEM photographs. ESR measurements have revealed that phthalocyanine molecules disperse very well in the codeposited thin films in a molecular level in comparison with the physical mixture of phthalocyanine powders. This high dispersibility of the molecules in the codeposited thin films can play a role to improve the reversibility in the electrochromism. Thus, the reversibility of the phthalocyanine, which shows irreversible electrochromism in the simple film form, can be improved by the codeposition with another phthalocyanine with reversible electrochromism. In contrast, sequentially deposted double‐layered thin film gives completely different results. The electrochromism of the double‐layered film depends on the property of the simple phthalocyanine thin film which is in contact with the substrate.
Electron transfer reaction of electrochemically polymerized tris‐(amino‐phenanthroline)‐iron(II/III) complex films
Authors: Kitagawa Mako , Iwaku Masahiro , Oyama Noboru 
Published: April 2003

AbstractNew films of iron complex with 4,7‐bis(2‐aminophenyl)‐methylaminosulfonylphenyl)‐1,10‐phenanthroline (APP) and 5‐amino‐1,10‐phenanthroline (AP) are prepared on the electrode surface of In–Sn oxide conducting glass (ITO) by electrochemical oxidation. The thickness (Φ) of the films prepared on the ITO can be controlled by the number of cycles of the potential scan. The resulting film‐coated electrodes show well‐defined reversible vol‐tammograms corresponding to the redox reaction of the Fe(II/III) complexes in 0.1 M NaClO4 acetonitrile (AN), a mixture of butylene carbonate (BC) and propylene carbonate (PC) and poly2‐hydroxyethylmethacrylate gel containing BC and PC. The electron transfer processes within the films can be treated apparently as diffusional processes characterized by the rate constants of the apparent diffusion coefficient (Dapp). The value of Dapp increase from 1.0 × 10−9 to 1.6 × 10−8 cm2 sec−1 as the Fe complex concentration (CFe) increases from 0.06 to 1.04 M for the [Fe(AP)3] complex film (Φ=0.80 μm) in 0.2 M NaClO4/AN solution. The Dapp value for the [Fe(APP)3) complex film (CFe = 0.19 M, Φ= 0.78 μm) is 3.5 × 10−9 cm2 sec−1 in 0.2 M NaClO4/AN solution. The Dapp values of the [Fe(AP)3] complex film in the PC + BC mixture and gel containing 1.0 M NaClO4 were smaller than those obtained in AN solution by an order of magnitude. The dependence of the apparent formal potential of the Fe(II/III) redox reaction for the [Fe(AP)3] complex film on the activity of NaClO4 supporting electrolyte in AN shows that Na+ moves preferentially across the polymer/solution interfaces during the redox reaction. The Fe(II/III) redox reaction of the Fe complex films shows reversible electrochromic response between red and colorless.
Approach to improving the toughness of TGMDA/DDS epoxy resin by blending with thermoplastic polymer powders
Authors: Pascal T. , Bonneau J. L. , Biolley N. , Mercier R. , Sillion B. 
Published: April 2003

AbstractA series of hot‐melt processable thermosetting compositions was prepared by blending N,N,N′,N′‐tetraglycidyl‐4,4′ ‐diaminodiphenyl‐methane/4,4′‐diaminodiphenylsulfone (TGMDA/DDS) epoxy resin and thermoplastic polymer powders with average particle size below 30 μm. The basic thermoplastic polymers were either a high Tg amorphous cardo polyimide (Tg=350°C) or commercial semicrystalline PA6 and PA12 polyamides. The resulting heterogeneous mixtures showed viscosity values below 5000 cps suitable for prepregging process. After cure, phase‐separated morphologies were maintained with a rather limited interphase miscibility as demonstrated by thermomechanical analysis. Scanning electron microscope examination of fracture surfaces pointed out a strong adhesion between the powder particles and the surrounding polyepoxy network, particularly for the potentially reactive polyamide structures. Moreover, as shown by differential scanning calorimeter analysis, the crystallinity ratio of the PA6 and PA12 powders was lowered due to melting during thermal polymerization. The fracture toughness properties of the powder‐containing materials were compared with those of a fully miscible cardo polyimide–TGMDA/DDS blend coming from an homogeneous resin composition. The best improvement in fracture energy was obtained for the powder‐modified resins. The most effective composition filled with 16 wt% of powdered polyimide exhibited a fourfold increase in GIC (388 J/m2 versus 100 J/m2) without compromising the epoxy thermomechanical stability (Tg=227°C versus 223°C).
Second‐order nonlinear optical properties of side‐chain liquid crystalline polymers studied by second harmonic generation from thin films
Authors: Alastair D. , Smith McL. , Coles Harry J. 
Published: April 2003

AbstractThe two independent elements of the second‐order nonlinear optical susceptibility tensor of a range of contact poled, donor–acceptor substitued side‐chain polymers are reported. The susceptibilities were measured by second harmonic generation from thin films, typically less than 0.5 μm thick, at a fundamental wavelength of 1064 nm. The largest value was χ = 2.64 pm/V which is three times greater than the χ value of KDP and was measured in a nitrobenzylidene side chain, polyhydroxystyrene polymer with an eleven unit alkyl chain spacer attaching the side group to the backbone. Typical susceptibility values obtained were χ∼0.3 pm/V and X(2)33∼1 pm/V. The coherence lengths of the materials, which lay in the range 4–12 μm, were measured at 1064 nm by the maker fringe technique using thick, wedge‐shaped samples.
Crystallization of carboxylic acid salts in poly(ethylene oxide) oligomers at higher temperatures
Authors: Ohno Hiroyuki , Kawanabe Hisashi , Ito Kaori 
Published: April 2003

AbstractMany alkali metal carboxylates when dissolved in poly(ethylene oxide) (PEO) oligomers, are phaseseparated by heating. These were revealed to be the crystals of the initially dissolved corresponding salts from the X‐ray diffraction patterns. Some acetate salts achieve the lower limit of the lattice energy for phase separation of ordinary inorganic salts by heating in PEO oligomers. These carboxylate salts were therefore expected to show crystallization behavior in PEO oligomers by heating. The effects of cation size, alkyl chain length and molecular weight of PEO on the solubility are summarized. Negative temperature dependence of solubility of these acetate salts is seen in the PEO oligomers only when the salts have long alkyl chains. The salts containing larger cations needed a longer chain length of PEOs for crystallization by heating. These salts with longer alkyl chains showed positive temperautred dependence in lower molecular weight polyethers, but negative temperature dependence in solubility in PEO with molecular weights higher than 400. In PEO400, all the carboxylates with longer alkyl chains were phase separated by heating.
Coalescence of polystyrene nodules in soft poly(butyl acrylate)‐based films
Authors: Hidalgo Manuel , Cavaillé Jean‐Yves , Cabane Bernard , Chevalier Yves , Guillot Jean , Ríos Leonardo , Vassoille René 
Published: April 2003

AbstractA two‐stage emulsion polymerization procedure was used in order to obtain core–shell polymer particles having a core of polystyrene (PS), covered by a shell of either pure poly(butyl acrylate) (PBA) or a methacrylic acid‐functionalized PBA. Films were then cast from these latexes, and their properties were studied without further treatments (“as‐dried” films), as well as after a 3 hr heat treatment intended to provoke the coalescence of PS domains (“annealed” films). “As‐dried” and “annealed” film samples were studied by dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and small angle neutron scattering (SANS). DMA and SEM results, as described in previous works, showed that for unfunctionalized films, the percolated PS domains coalesced under the annealing treatment, while for the functionalized films, they did not. On the other hand, SANS results presented here showed that even in the case of functionalized films, the presence of coalescence could be detected. It was concluded that while DMA and SEM reveal large‐scale modifications provoked by the heat treatment, SANS is capable of detecting very smallscale changes which do not have a direct effect on the bulk physical properties of the samples.
Transmission electron microscopy observations of composite polymer colloid nucleated by functionalized silica
Authors: Gauthier C. , Thollet G. , Vigier G. , Bourgeat‐Lami E. , Guyot A. 
Published: April 2003

AbstractIn this work, functionalized nanometric silica particles were engaged in emulsion polymerization of ethyl acrylate. The morphological characterization of this composite material was performed by transmission electron microscopy (TEM) and small angle X‐ray scattering (SAXS). We were particularly interested in the state of encapsulation of the silica particles and their distribution in the latex film. Initialy, we successively studied both components of the composite: polymer beads and silica particles differ by their size and also by their contrast. In addition, it was possible to perfrom dark field TEM to study this system of two amorphous phases because their respective amorphous halos are not too close. Hence, we investigated the colloid material in aqueous media and after film formation. Although no ideal encapsulation is observed in the colloid in aqueous media, the distribution of silica in the latex film is good. SAXS results are in good agreement with TEM observations.