bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interpenetrating blends of rigid aromatic fractal polyamides and nylon‐6
Authors: Aharoni Shaul M. 
Published: April 2003

AbstractBlends of nylon‐6 and up to 20% rigid aromatic fractal polyamides (FPs) were prepared by precipitation from a mutual solvent and by two melt‐processing procedures. In general, no grafting of the flexible linear nylon chains onto the rigid FPs took place, but in several instances of melt‐blending of nylon with FPs whose amine end‐groups were exposed, a low level of grafting occurred.The glass transition temperature and the tensile modulus and yield strength of the blends were greatly elevated as function of the FP concentration in the blends. This was demonstrated to be caused by the openness and rigidity of the FPs, and the connectivity of the FP segments through rigid branchpoints. The great porosity of the FPs allows the chains of the amorphous fraction of the nylon to interpenetrate and pass through the FPs, and the stiff segments of the FPs to suppress the chain motions of the nylon, which accounts for the enhanced glass transition temperature (Tg) and tensile properties. When non‐porous amorphous silica particles or stiff linear or essentially unbranched zigzag polyamides were blended with the nylon, the Tg of the nylon either did not change at all or changed only very little. Several analytical procedures were used to verify that the nylon chains occupied most of the free space in the pervaded volumes of the FPs in the as‐prepared blends and filled this space completely when these blends were compression‐molded. The point where the FPs filled all the volume of the amorphous fraction of the nylon‐6 was reached between 5 and 7.5% FP concentration. Below this, traces of the original nylon‐6 Tg could be occasionally detected. Above it, only the high Tg of the nylon chains interpenetrated in the FPs was detected.
Synthesis and properties of the addition polymer of benzenedithiol with divinylbenzene
Authors: Kobayashi Eiichi , Kuribayashi Ryotaro , Aoshima Sadahito 
Published: April 2003

AbstractPolyaddition of 1,4‐benzenedithiol (BDT) to 1,4‐divinylbenzene (DVB) was carried out with 2,2′‐azobisisobutyronitrile initiator in toluene at 75°C under a nitrogen atmosphere. The polymerization proceeded without an induction period, to give a white polymer with a high molecular weight (M̄w = 110,000) in ca. 90% yield for 2 hr. It was confirmed by 1H‐NMR (nuclear magnetic resonance), IR (infrared) and sulfur contents that the polymer had an alternating structure of DVB and BDT units. The end‐capping reaction of the polymer was also achieved by addition of thiophenol and/or styrene to the polymerization solution at a final stage of the polymerization. The polymer film exhibited a reversible phase transition between a transparent state and an opaque one by thermal mode. The thermal property of the polymer was studied by differential scanning calorimetry (DSC) analysis and polarized optical microscope observation with the polymer film. The detailed DSC analysis showed that the end‐capped polymer with a relatively low molecular weight (M̄W = 4400–9600) exhibited similar to liquid crystalline behavior. A diffuse reflectance spectrum of the polymer coated on an aluminum plate showed a marked difference in reflective light intensity in the ultraviolet and visible regions: the reversible phase transition between an opaque and a transparent polymer layers was induced by thermal mode. The light transmittance of the polymer film, which was measured by depolarized light intensity method, was very sensitive toward the temperature variation.
ABA triblock copolymer containing two crystallizable components
Authors: Shih Hsiao‐Yi , Kuo Wen Faa , Pearce E. M. , Kwei T. K. 
Published: April 2003

AbstractA triblock copolymer of the ABA type in which both components were crystallizable was synthesized. The A block was poly(ethylene oxide), PEO, and the B block, poly(dimethyl siloxane), PDMS. Upon cooling from the melt to liquid nitrogen temperature, the PEO block crystallized at around 40°C. When the copolymer was heated from −170°C after quenching, glass transition, crystallization and melting of the PDMS middle block were identified in the thermogram at −117°C, −74°C and −42°C, respectively. The degree of crystallinity of the PDMS block was estimated from the heat of fusion to be about 27%. The growth rates of the PEO spherulites were reduced by the presence of the middle block.
Emulsion copolymerization of styrene with monomeric emulsifiers
Authors: Goebel K.‐H. , Stähler K. 
Published: April 2003

AbstractMonomeric emulsifiers with different copolymerization reactivities were used as stabilizers in emulsion polymerization of styrene initiated by 2,2′ azobisisobutyronitrile (AIBN). A significant change in emulsifier function was observed between equal micellar concentrations of surface‐active sodium sulfopropyl alkyl maleates and the corresponding sodium sulfopropyl dodecyl fumarate. In the presence of less reactive maleates, copolymerization mainly occurs in the interface of the monomer swollen particles, while copolymerization with the fumarate in the first period of emulsion polymerization leads to polyelectrolyte formation in the water phase.
Emulsion copolymerization of styrene with a nonionic styrenic polymerizable surfactant
Authors: Filet A. , Guillot J. , Hamaide T. , Guyot A. 
Published: April 2003

AbstractAmong the variety of possible structures for polymerizable surfactants, it seems clear that the most interesting should be those with the reactive group located in the hydrophobic part of the molecule. We report here a study based on such a surfactant. Its general formula is

A set of surfactants has been produced with m varying from 23 to 48 and n = 6 or 12. The compounds have been characterised by 1H‐NMR (nuclear magnetic resonance), size exclusion chromatography, surface tension measurements and turbidimetry.These surfactants have been copolymerized with styrene in emulsion polymerization. The coagulum is rather important, except if m is large enough. Although the incorporation of the surfactant in the latex is rather high. Most of the anchored surfactant remains at the surface and is not too buried inside. The particle size decreases with both the amount of surfactant and the length of its hydrophilic part. The use of these polymerizable surfactants leads to an excellent stability of the latex against the addition of electrolytes, and also against freeze‐thawing constraints.
Preparation and characterization of cationic poly(n‐isopropylacrylamide) copolymer latexes
Authors: Meunier F. , Elaïssari A. , Pichot C. 
Published: April 2003

AbstractCationic poly(N‐isopropylacrylamide) (NIPAM) copolymer latexes have been prepared at 70°C using methylene‐bisacrylamide (MBA) as the crosslinking agent,2‐2′‐azobis‐(2‐amidinopropane hydrochloride) (V50) as the initiator and in the presence of 2‐aminoethyl‐methacrylate hydrochloride (AEM). It was found that the concentration of AEM plays a major role in the polymerization kinetics and particle nucleation. However, too high a concentration (2–5 mol%/NIPAM) caused the latex to be polydispersed together with the production of large amounts of polyelectrolytes. The presence of surface amino groups on the final particles under the protected form was revealed both by an ultraviolet spectrometry and nuclear magnetic resonance methods. It was indirectly evidenced through the electrophoretic mobility behavior of the latex particles (below and above the lower critical solubility temperature of the poly(NIPAM)) as well as by their stability against a monovalent electrolyte.
Interactions between temperature‐sensitive hydrogel microspheres and granulocytes
Authors: Achiha Koji , Ojima Rika , Kasuya Yuji , Fujimoto Keiji , Kawaguchi Haruma 
Published: April 2003

AbstractPoly(N‐isopropylacrylamide) (PNIPAM) has a low critical solution temperature (LCST) at 32°C in water and the hydrophilicity changes through the LCST. The microspheres whose surface was composed of PNIPAM exhibited phase transition behavior around 32°C. Therefore, the interactions between PNIPAM micropheres and granulocytes depended on the temperature. That is, the oxygen consumption and active oxygen production by cells in contact with PNIPAM‐containing microspheres and adhesion of the microspheres to the cell surface were more enhanced above the LCST of PNIPAM than below it, whereas no significant temperature dependence of cell–microspheres interaction was observed in nonthermosensitive microsphere systems. It was suggested that the function of cells could be controlled with temperature using the temperature‐sensitive microspheres.
Mixing device for polymer blends of very different molecular weights using a mixing nozzle process
Authors: Saeda Shigeru , Suzaka Yukinori 
Published: April 2003

AbstractA new method of blending two polymers with very different molecular weights, i.e. different melt viscosities, in which the polymer mixture is forced to pass through a nozzle with a conical taper is proposed in this study.High density polyethylenes with very high and very low molecular weights were used as the samples in the blending process, and the parameters that affected the homogeneity of the blended polymers were studied. The homogeneity was found to be better at a lower shear rate, smaller orifice diameter, higher compression ratio of the cross‐sectional area of the nozzle entrance and orifice, and a small length‐to‐diameter ratio of the orifice. This blending process, the nozzle blend, was found to make the droplets of a high molecular weight component extend to thin fibers along the conical section of the nozzle.The nozzle blend system has been proved to be useful in obtaining both macroscopic and microscopic homogeneity, and has been estimated to be comparable to a few minutes of roll‐mill blending.
Mixing efficiency for polymer blends of very different molecular weights by using a mixing nozzle
Authors: Saeda Shigeru , Suzaka Yukinori 
Published: April 2003

AbstractA way to mix polymer blends of very high and low molecular weights by using a mixing nozzle is presented. An array of blend nozzles with a conical inlet attached to a single screw extruder was used to blend polyethylene homopolymers with very different molecular weights. Using extruders with 30 and 50 mm barrel diameters, the effects of nozzle dimensions and operation conditions with respect to the homogeneity were studied.The device proved useful in obtaining a good macroscopic and molecular homogeneity up to 30 kg/hr by the 50 mm extruder, though care must be taken to avoid the degradation of polymers by heat and shear, especially in the extruder.The key factor ruling the efficiency of blending was found to be the compression ratio, i.e. the ratio of the cross sectional areas of the entrance of the nozzle and that of the orifice, and the shear rate at the orifice.For the nozzle with geometrically similar figure, the critical shear rate at which the homogeneity began to worsen was the same. Scale‐up of the nozzle could be accomplished by enlarging the diameter of the diameter of the orifice, yet maintaining a geometrically similar figure. The maximum output of the nozzle is proportional to the third power of the orifice diameter.
Effective formation of fullerenes by pyrolysis of decacyclene
Authors: Minakata Takashi 
Published: April 2003

AbstractThe pyrolysis of polyconjugated hydrocarbons containing five‐membered rings such as decacyclene and acenaphthylene under argon atmosphere was carried out. The vaporized source molecules were heat‐treated above 700–1000°C to yield a black soot product, which was subsequently extracted with chloroform to give a black amorphous solid. Formation of C60, as the main product was confirmed by mass spectroscopy. These results indicated a new preparation process of C60 from hydrocarbons, which differs from the conventional method of vaporization of carbon. The formation mechanism of fullernes by the pyrolysis of polyaromatics is discussed.
The environmental stress cracking of linear ethylene copolymers
Authors: Saeda Shigeru , Suzaka Yukinori 
Published: April 2003

AbstractA new method of measuring the environmental stress cracking (ESC) of polymers at constant strain is proposed in which an occurrence of fracture is detected automatically. The new method showed a very good reproducibility within 10% compared with a few hundred percent by conventional methods.The ESC values obtained by the new method was found to be proportional to those by the conventional Bell Telephone Laboratory method in which the ESC was determined by the occurrence of small cracks, with a proportionality contant of 2.8. From the fact that the difference of both ESCs were also proportional to the ESC determined by the BTL method, it was concluded that the value of the ESC was proportional to the velocity of crack propagation. These conclusions were supported by the observation of the test pieces by a scanning electron microscope.The study of the blended polymers revealed that the additivity of logarithmical ESC with weight fraction holds for a wide range of polymes, which enables estimation of ESCs up to millions of hours.Using this technique, the ESCs of a wide range of molecular weights and a number of short chain branches were studied. It was found that the branches in the high molecular weight polymer were much more effective on the ESC than those in the low molecular weight polymer. This makes it possible to design a good resin with a good ESC.
Electrical conductivity of alternate layer deposition of pentancene and tetracene superlattices
Authors: Minakata Takashi , Mori Yoshihiko 
Published: April 2003

AbstractSuperlattice thin films of pentacene (PEN) and tetracene (TET) were fabricated by alternate layer deposition using the sublimation method. The film showed a highly crystalline structure that was due to the strong aggregation tendency of polyacene compounds to form a layered monomolecular column structure. The crystalline structure of the films was drastically changed by doping with iodine. The doped films showed a highly ordered structure where an iodine monomelecular layer was intercalated between molecular columns of acene compounds in both PEN and TET. The doped films exhibited a large lateral conductivity of 10 Ω−1 cm−1 and attained giant anisotropy above 1012. This indicated that molecular columns of TET remained insulating upon doping to form a perfect two‐dimensional conductor in the superlattice thin films.
Phase behavior and structure formation in ternary blends: studies on blends of PVDF/PMMA/PVAC
Authors: Classen S. , Vogt M. , Wendorff J. H. 
Published: April 2003

AbstractThe phase behavior of ternary blends was analyzed on the basis of the lattice approach. Both compatibilization and incompatibilization effects are predicted to occur depending on the relative magnitudes and the sign of the interaction parameters of the binary subsystems. Thermodynamic, structural and kinetic properties were investigated for a ternary model blend composed of poly(vinylidene fluoride), poly(methyl methacrylate) and poly(vinyl acetate). This particular ternary system is characterized by a specific symmertry with respect to the interactions in the binary subsystems. This symmetry affects both thermodynamic and structural properties. The experimentally determined interaction parameters were used to model the phase diagram on the basis of the lattice model: the theoretical phase diagram was found to be close to the experimental one. The crystallization processes were analyzed both for the binary and the ternary systems on the basis of a modified Turnbull–Fisher equation. The conclusions are that the properties of the ternary systems can be understood to a first approximation on the basis of those of the corresponding binary systems and the symmetry of the interactions.
Functionalization of montmorillonite by acrylamide polymers containing side‐chain ammonium cations
Authors: Biasci Luca , Aglietto Mauro , Ruggeri Giacomo , D′Alessio Aldo 
Published: April 2003

AbstractStable polyacrylamide (polyAA)–montmorillonite adducts were prepared by two distinct processes: (1) free radical copolymerization of AA with alkaline clay previously treated with 2‐(N‐methyl‐N,N‐diethyl ammonium iodide)ethylacrylate (QD1) and (2) direct interactions of alkaline montmorillonite with various preformed copolymers of AA with QD1. The structure of the adducts as determined by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry and X‐ray diffraction was shown to consist of AA macromolecules inserted between lamellar layers whose spacing was larger than in the polymer‐free clay. The polymer was strongly attached to the inorganic surfaces, probably due to cooperative formation of electrostatic bonding. The thermal stability of the organic polymers in the resulting complexes was substantially enhanced while the mobility of macromolecules decreased.
Solid‐phase rheology of an anisotropic polymer (vectra A)
Authors: Devens Douglas A. , Denn Morton M. 
Published: April 2003

AbstractThe solid‐phase rheology of a thermotropic polyester which is liquid crystalline in the melt (Vectra A) was studied for one‐dimensional finite‐amplitude deformations, including step‐strain and recovery, step‐stress and recovery, and step‐strain followed by small‐amplitude oscillations. The rheology is complex, and cannot be described by existing models. Below a critical strain, which is history‐dependent, Vectra A deforms as a linear viscoelastic solid. Above the critical strain the deformation is both viscoplastic and viscoelastic. There appears to be a maximum recoverable strain of about 0.03, beyond which all deformation is nonrecoverable. A large number of relaxation modes is required to describe the stress, and one time scale is inadequate to describe the time‐dependence of yielding and plastic flow.
Organic electroluminescent device with an aromatic amine‐containing polymer as a hole transport layer (I): Poly[N‐[p‐N′ ‐phenyl‐N′‐[1,1′‐biphenyl‐4′‐[N″‐phenyl‐N″‐(2‐methylphenyl)amino]‐4‐amino]]phenyl methacrylamide]
Authors: Kido Junji , Komada Masaki , Harada Gaku , Nagai Katsutoshi 
Published: April 2003

AbstractElectroluminescent devices were fabricated using a holetransporting polymer, poly[N‐[p‐N′ ‐phenyl‐N′‐[1,1′‐biphenyl‐4′‐[N″‐phenyl‐N″‐(2‐methylphenyl)amino]‐4‐amino]]phenyl methacrylamide] (PTPDMA), and tris(8‐quinolinolato)aluminum(III) complex, Alq, as the hole transport layer and the emitter layer, respectively. A device structure of glass substrate/indium–tin–oxide/PTPDMA/Alq/Mg:Ag was employed. Hole injection from the electrode through the PTPDMA layer to the Alq layer and concomitant electroluminescence from the Alq layer were observed. Bright green luminescence with a luminance of 20,000 cd/m2 was obtained at a drive voltage of 14 V.
Orientation studies in polyacrylonitrile films uniaxially drawn in the solid state
Authors: Bashir Zahir , Tipping Alison R. , Church Stephen P. 
Published: April 2003

AbstractPolyacrylonitrile (PAN) films were made by casting a dimethyl sulphoxide (DMSO) solution. After drying, the films were uniaxially drawn by an essentially solid‐state drawing procedure. Using polarised‐infrared (IR) spectroscopy, the dichroism of the nitrile‐stretching vibration was monitored as a function of draw ratio. The dichroism results were converted to plots of chain‐orientation factor versus draw ratio. For this, α, the transition‐moment angle of the vibration, has to be known. Though a value of 68–73° has been suggested in the literature, for the present samples α cannot be 70° or less, and 73° is the most appropriate. The meaning and nature of the transition‐moment angle in the context of a flexible‐chain polymer molecule is discussed. The IR spectrum also showed dichroism in the SO stretch and the CH3 rocking vibrations from the (residual) DMSO present in the film, indicating that the solvent molecules were also orientated. It is proposed that this occurred due to dipolar interactions between the SO and the CN groups, which led to solvent molecules being bound to the polymer chains. X‐ray diffraction studies indicated ‘lateral‐ordering’ consisting of hexagonally packed, rod‐like chains with no c‐axis order. The diffraction patterns obtained here were the ‘standard’ ones for PAN, in contrast to those observed previously in solvent‐containing PAN gels.
Optical activity measurements in solids 5. Optical rotation of natural polymers
Authors: Bartuš Ján , Vogl Otto 
Published: April 2003

AbstractThe optical activity of ten natural‐type polymers [poly(α‐aminoacids), polysaccharides, proteins and nucleic acids] was measured in solution, as solid powders in suspension, and where possible in the form of films. In some cases the specific rotation of powder samples showed significant differences to the values obtained from solution measurements. The discrepances seem to reflect the arrangements of polymer chains in supermolecular assemblies in the polymer solid state.
Crystalline oligomeric stereocomplex as an intermediate compound in racemic poly(DL‐lactic acid) degradation
Authors: Li Suming , Vert Michel 
Published: April 2003

AbstractHydrolytic degradation of intrinsically amorphous poly(DL‐lactic acid) was re‐examined in pH 7.4 isoosmolar phosphate buffer at 37°C. Size‐exclusion chromatogarphy, X‐ray scattering and differential scanning calorimetry were used to monitor molecular weight and morphology changes up to the ultimate degradation stage. It was found that heterogeneous degradation of poly(DL‐lactic acid) yielded a crystalline residual material of low molecular weight. Comparison with a stereocomplex made of equimolar poly(L‐lactic acid) and poly(D‐lactic acid) showed that the poly(DL‐lactic acid) degradation residue was actually an oligomeric stereocomplex. The formation of stereoregular oligomeric enantiomers agreed well with the predominantly isotactic structure of poly(DL‐lactic acid) obtained by ring‐opening polymerization of DL‐lactide and argued in favour of the stereodependence of main chain ester bond cleavage.
Alternating, all‐trans polyenynes: Model compounds for poly(diacetylene)s with defined conjugation length
Authors: Giesa Reiner , Schulz Rolf C. 
Published: April 2003

AbstractThe syntheses of polyenynes as model compounds for poly(diacetylene)s (PDAs) are described. Variation of properties (UV–VIS, Raman, NMR and bond geometries) as a function of the chain length was investigated. After extrapolation to infinite chain length these data were compared to those for PDAs. From UV–VIS spectra a value of λ = 551 nm (2.25 eV) was calculated corresponding to the electronic transition of a single polyenyne chain. This energy is located at the low energy end of a yellow PDA solution spectrum. From Raman scattering v(CC) = 2108–2128 cm−1 and v(CC) = 1505–1532 cm−1 were calculated after extrapolation. Similarly sp‐C13C NMR data yielded a shift of δ = 100 ppm. These data are almost identical to data known for yellow PDA solutions. Bond geometries are almost identical to those of poly(diacetylene)s and theoretical data.
Thermal and spectroscopic properties of the polydiacetylene derived from docosa‐10,12‐diyne‐1,22‐diylbis(phenylacetate)
Authors: Lindsell W. Edward , Preston Peter N. , Tomb Peter J. 
Published: April 2003

AbstractPolydiacetylene (2) of varying molecular weight has been formed by UV‐ or 60Co γ‐irradiation of the diacetylene PhCH2CO2(CH2)9‐CCCC(CH2)9O2CCH2Ph (3), with conversion of 30−>95%. Samples of (2) with differing physical properties have been studied, in the bulk phase, by CPMAS 13C NMR and VIS/UV spectroscopy and by DSC; complementary spectroscopic data on solutions of (2), including fluorescence studies, are also reported. Spectroscopic studies support the presence of an extended planar conjugated backbone in ‘as polymerised’ blue–black samples of (2), from which various forms of red‐coloured polymer, with shorter conjugation lengths, can be obtained. Studies of the thermal behaviour indicate the existence of several differing thermal transitions for these materials and the results are discussed.