bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of the carbon fiber–Poly(Ether–Ether–Ketone) (PEEK) interfaces, 3: influence and properties of interphases
Authors: Nardin M. , Asloun E. M. , Muller F. , Schultz J. 
Published: April 2003

AbstractThe aim of this third part is to analyze the structure and properties of the interfacial region between carbon fibers and PEEK as a function of different thermal conditioning treatments. First, it is shown by means of optical microscopy that the interfacial zone is not different from the bulk matrix when standard cooling conditions are used. On the contrary, a transcrystalline interphase is formed near the carbon fiber surface in systems that have been subjected to isothermal treatments. By comparison with previous results concerning the mechanical properties of the fiber–matrix interface, it appears that the interfacial shear strength decreases in the presence of a transcrystalline interphase or when the crystallization rate of PEEK increases. Moreover, it seems that the “constraint state” of the amorphous phase of PEEK near the fiber surface could also play a role in the interfacial shear strength. Secondly, a method is proposed in order to estimate the elastic modulus of crystalline interphases. It seems that this modulus is strongly dependent on the crystallization rate of the polymer. Finally, the determination of the stress‐free temperature, defined as the temperature at which a longitudinal compressive stress just appears on the carbon fiber during the processing of the composites, is performed by recording the acoustic events corresponding to the fragmentation process in single‐fiber composites. The results confirm that the crystallization rate and the “constraint state” of the amorphous phase of the matrix play an important role in the mechanical behavior of carbon fiber–PEEK interfaces.
Improvements in aluminum adhesion and breakdown voltages of polyvinylidene fluoride films following exposure to gas plasmas
Authors: Mammone Robert J. , Wade William L. , Binder Michael 
Published: April 2003

AbstractChanges in water wettability, improvement in adhesion of vapor deposited aluminum and increases in dielectric breakdown voltage in thin, 12 micron PVDF films were observed following brief exposure of these films to low‐temperature gas plasmas.
Polyelectrolyte‐like behavior of polyethylene oxide/LiClO4 mixture in chloroform or chloroform/dimethylformamide mixed solvent
Authors: Ohno Hiroyuki , Ito Yasushi , Yamaguchi Natsue 
Published: April 2003

AbstractLithium perchlorate (LiClO4) was dissolved in dehydrated chloroform with polyethylene oxides (PEO) having different molecular weights. The mixing ratio of ether oxygen unit (O) of PEO to cation (Li+) was set to 20:1. The solution viscosity of the PEO/LiClO4 mixtures was measured using an Ubbelohde viscometer at 30.0°C. The concentration dependence of the reduced viscosity was analyzed by diluting the initial PEO/LiClO4 mixed solution with pure chloroform to keep the ratio of Oto Li+ constant. The increase in the reduced viscosity for a dilute solution was found in every mixture system, but not in the PEO solution without salt. Similar experiments were also carried out in chloroform/dimethylformamide (DMF) mixed solvent (4:1 by volume). These results were analyzed using the Fuoss equation, which was applied for the analysis of a polyelectrolyte aqueous solution. Linear relations are depicted in the Fuoss plots, suggesting that the PEO/LiClO4 mixture shows polyelectrolyte‐like behavior in chloroform or in chloroform/DMF mixed solvent. This is attributed to the intramolecular electrostatic repulsion of lithium cations which are trapped by the PEO chains through ion–dipole interaction.
Thermal dimensional stability of isotropic polyoxymethylene
Authors: Zahran Rouchdy R. , Abolmagd Abir A. 
Published: April 2003

AbstractA parametric mapping analysis of the effect of various structural and morphological parameters on the thermal dimensional stability of polyoxymethylene is highlighted. The molecular composites model is found to describe adequately the expansional behavior of isotropic polyoxymethylene. The thermal expansivity is highly sensitive to the level of crystallinity followed by the transverse dimension of the crystallites. The longitudinal dimension of the crystallites, however, is not effective in altering the expansion behavior of isotropic polyoxymethylene. When comparing the model calculations with experimentally published data, an agreement of better than 15% is observed.
Quinone‐modified polymers as electron transfer relay systems in amperometric glucose sensors
Authors: Karan H. I. , Hale P. D. , Lan H. L. , Lee H. S. , Liu L. F. , Skotheim T. A. , Okamoto Y. 
Published: April 2003

AbstractA polysiloxane and an acrylonitrile–ethylene copolymer with covalently attached p‐hydroquinone/benzoquinone moieties were prepared and tested as electron transfer relay systems in amperometric glucose biosensors. Using experiments involving cyclic voltammetry and stationary potential measurements, it was shown that the polysiloxane relay system can efficiently mediate electron transfer from reduced glucose oxidase to a conventional carbon‐paste electrode. Sensors containing this polymeric relay system and glucose oxidase respond rapidly to low (<0.1 mm) glucose concentrations, with steady state current responses achieved in less than 1 min. The acrylonitrile–ethylene copolymer was found to be less efficient than the polysiloxane system at mediating the electron transfer from reduced glucose oxidase to the electrode. The dependence of the sensor response on the nature of the polymer backbone is discussed.
Resolution of lymphocyte subpopulations derived from rat spleen by polyamine‐graft‐PHEMA copolymer
Authors: Kikuchi Akihiko , Mizutani Shinji , Kataoka Kazunori , Tsuruta Teiji 
Published: April 2003

AbstractThe retention behavior of lymphocyte subpopulations, B cell, T cell and null cell, derived from rat spleen to polyamine‐graft‐poly(2‐hydroxyethyl methacrylate) copolymer (HA) surface was investigated, focusing on the conformational transition of the polyamine side chain as well as the protonation of amino groups in the polyamine grafts. Furthermore, the availability of HA was discussed as a column adsorbent for separation of lymphocyte subpopulations derived from spleen. The conformational transition of polyamine grafts significantly influenced the mode of retention of lymphocyte subpopulations. When polyamine grafts existed in an aggregated conformation (protonatin degree α < 0.5), the retention of lymphocyte subpopulations was decreased in the order B cell> null cell> T cell. On the other hand, when polyamine existed in an extended conformation into the aqueous interior from the matrix interface (α > 0.5), T cell retention became greater than null cell retention, resulting in a decreased B cell> T cell> null cell order. These results indicate that the differential retention of spleen lymphocyte subpopulations is attributed to their differential responses to the change in matrix interface accompanied by the protonation of amino groups. Furthermore, spleen lymphocytes were compared with lymph node lymphocytes in terms of resolution efficacy by an HA copolymer column.
Effect of the incorporation of amino groups in a glucose‐responsive polymer complex having phenylboronic acid moieties
Authors: Kitano Shigeru , Hisamitsu Issei , Koyama Yoshiyuki , Kataoka Kazunori , Okano Teruo , Sakurai Yasuhisa 
Published: April 2003

AbstractA novel polymer complex system sensitive to glucose was studied as a candidate material for formulating a chemically regulated insulin release system. A ternary copolymer of N‐vinyl‐2‐pyrrolidone (NVP), 3‐acrylamidophenylboronic acid (AAm‐PBA) and N,N‐dimethylaminopropylacrylamide (DMAPAA) (poly(NVP‐co‐PBA‐co‐DMAPAA)) was synthesized by radical copolymerization. The phenylboronic acid group in this copolymer serves as a glucose sensor moiety. Poly(NVP‐co‐PBA‐co‐DMAPAA) was soluble in water in the pH range of 3–12, in sharp contrast to a binary copolymer of NVP and AAm‐PBA (poly(NVP‐co‐PBA)) which showed solubility only under alkaline aqueous conditions, where the boronic acid group is in a tetrahedral ionized form. The protonated amino group in poly(NVP‐co‐PBA‐DMAPAA) contributed to increase the solubility of the polymer under physiological and acidic aqueous conditions. Furthermore, poly(NVP‐co‐PBA‐co‐DMAPAA) formed a stable polymer complex gel with poly(vinyl alcohol) (PVA) in pH 7.4 phosphate buffered solution due to the formation of a covalent linkage between the boronic acid groups in ternary copolymer and diol units in PVA. The release of myoglobin as model protein from the complex gel was increased immediately after the addition of glucose, due to the transition of gel into sol state, indicating the feasibility of this complex gel as a candidate material for a glucose‐responsive delivery system for insulin.
Miscibility of poly(vinyl chloride) with poly(methyl‐co‐hexyl acrylate) and poly(methyl‐co‐2 ethyl hexyl acrylate)
Authors: Jin Byung Suk , Kim Sung Chul 
Published: April 2003

AbstractThe miscibility and phase behavior in blends of PVC with poly(methyl‐co‐hexyl acrylate)[MHA] and poly(methyl‐co‐2 ethyl hexyl acrylate)[MEH] were studied. It was found that PVC is miscible with MHA copolymers having a HA volume fraction from 0.30 to 0.92 and MEH copolymers having an EH volume fraction from 0.30 to 0.83 at 100°C. By applying the mean field theory to the phase diagrams of these blend systems, segmental interaction parameters which represent the binary interaction between different monomer units were estimated. The calculated values reflect the fact that the miscibility window observed for PVC/MHA and PVC/MEH blend systems was attributed to the effect of repulsion between different monomer units within the copolymer. To investigate the effect of specific interaction on the miscibility for these blend systems, an attempt was also made to describe the blend interaction parameter as a function of polar group concentration in the acrylate copolymer. The blend interaction parameter values exhibit a u‐shaped curve as a function of the weight fraction of CO group in the copolymer, and the lowest blend interaction parameter value appears at about 0.24 CO weight fraction.
Novel processable aromatic thermoplastic polyimides: Films, adhesives, moldings, and graphite composites
Authors: Kumar Devendra , Gupta Alka D. 
Published: April 2003

AbstractNovel hot‐melt type flexible, tough, thermally stable, processable, thermoplastic, aromatic polyimides have been synthesized involving reaction of a keto‐ether containing diamine with hinged aromatic dianhydrides followed by thermal and chemical cyclodehydration. Inherent viscosity in DMAC at 35°C of the synthesized polymers ranged 1.02 to 1.4 dl/g (0.5% solution). The polymers showed a glass transition temperature (Tg) of 250°C to 180°C as determined by differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). Thermogravimetric analysis showed polymer stability up to 510°C, in both air and nitrogen atmospheres. All the polymers have shown good melt‐flow. Films of 1.5–2.8 ml thickness were made and tested for mechanical properties at room temperature, 177°C and 210°C. The developed films are suitable for adhesion of Ti/Ti specimens and showed a lap shear strength of 5575 psi. Melt‐fusion of the polymers gave tough moldings. Graphite cloth composites have been made and tested for mechanical properties.
Blends of poly(carbonate) with poly(styrene) and poly(methylmethacrylate): phase morphology, mechanical, and thermal properties
Authors: Butzbach G. , Wendorff J. H. 
Published: April 2003

AbstractThis paper is concerned with the dependence of mechanical and thermal properties of heterogeneous blends of poly(carbonate) (PC) with poly(methyl‐methacrylate) (PMMA) and with poly(styrene) (PS) on the concentration of the components. PS displays a very weak phase coupling in blends with PC, whereas PMMA is characterized by a strong coupling to PC. Experimental results as well as predictions based on composite theories are reported.The general finding is that mechanical properties, such as the tensile modulus and the dynamic shear modulus, as well as thermal properties, such as thermal expansion, are (i) only weakly affected by the occurrence of a phase inversion and of a continuous phase morphology, (ii) vary continuously with the concentration of the components, and (iii) are rather insensitive to the strength of the phase coupling. The theoretical predictions on the concentration—property relationship for these properties, based on a self‐consistent approach, agree very well with those observed experimentally. The elongation at break as well as the yield stress, on the other hand, are strongly influenced by the nature of the phase coupling: a discontinuous variation of these properties with the composition is observed for PS/PC blends but not for PMMA/PC blends. The general conclusion is that a set of mechanical and thermal properties of heterogeneous blends can satisfactorily be predicted on the basis of rather simple composite theories.
Properties of block and graft copolymers of polybutadiene with small complexed poly(4‐vinylpyridine) segments
Authors: Janah Hakim , Favier Jean‐Claude , Sigwalt Pierre , Jačovič Mihaïlo S. 
Published: April 2003

AbstractVarious diblocks, triblocks and a graft copolymer of butadiene with 4‐vinylpyridine short blocks have been prepared. They were complexed with ZnCl2 to give ionomer‐like materials. For all copolymers, the Tg of the elastomeric block (−84°C to −91°C) was unchanged by complexation. For all diblocks and triblocks with short blocks (DPn ∼ 3) the storage modulus was only slightly increased by comparison with uncomplexed materials. For the graft copolymer even with short blocks the material is less sensitive to temperature after complexation. For triblocks, when the DPn of the vinylpyridine blocks was high enough (15 units), complexes were associated in multiplets of large size and the elastomeric properties were retained up to 200°C.
The thermal properties of poly(pivalolactone)
Authors: Grebowicz Janusz , Varma‐Nair Manika , Wunderlich Bernhard 
Published: April 2003

AbstractQuantitative thermal analysis was carried out for poly‐(pivalolactone) (PPVL), including heat capacity determinations from 140 to 550 K. The experimental Cp below the glass transition temperature was fitted to an approximate vibrational spectrum and the ATHAS computation scheme was used to compute the “vibration only” heat capacities from 0.1 to 1000 K. The liquid Cp was derived from an empirical addition scheme and found to agree with the experimental Cp with an RMS of ±2.8% from 240 K to 550 K. A glass transition, Tg, could be detected at 260 K, and the change in heat capacity for 100% amorphous PPVL was calculated to be 38.8 J/(K mol). Above Tg, semicrystalline samples seem to show a rigid amorphous fraction that does not contribute to the increase in heat capacity at Tg. Using the ATHAS recommended heat capacities, the various thermodynamic functions (enthalpy, entropy, and Gibbs function) were derived. The residual entropy at 0 K for the amorphous PPVL was calculated to be 5.2 J/(K mol) per mobile bead, and was comparable to that obtained for a series of linear, aliphatic polyesters analyzed earlier.
Ion transport in copolymers of oligo(oxyethylene) methacrylates with monomers having polar group
Authors: Xu Kang , Wan Guoxiang , Tsuchida Eishun 
Published: April 2003

AbstractCopolymers of oligo(oxyethylene) methacrylates and a series of polar comonomers, i.e. acrylamide, acrylonitrile and maleic anhydride, were synthesized as media for dual‐ or single‐ion conduction, and correlation between polymer structure and properties was established through detailed studies on polymer morphology, mechanical property and the ion transport process. Polar groups in the polymer chain sequence were found to enhance matrix polarity and to retard oligoether crystallization, as well as to raise chain rigidity. Therefore, both novel dual‐ and single‐ion conduction are realized, with a simultaneous improvement in the mechanical properties of polymer materials. An investigation about the effect of matrix polarity on the ion transport process is also carried out, making use of the concepts concerning polymer segmental relaxation. Hence the enhanced matrix polarity is found to contribute to the improvement in ion conduction, mainly through its promotion of salt dissociation. However, at high temperature this facilitation is counteracted due to the “anomalous” temperature‐dependence of salt dissociation in the polymer matrix, and the higher the matrix polarity, the more drastic is the drop in carrier number with rising temperature.
The alignment of LC side‐chain polymers in directing electric fields: theory and practice
Authors: Nazemi Ali , Williams Graham , Attard George S. , Karasz Frank E. 
Published: April 2003

AbstractThe factors that control the alignment of LC side‐chain polymers in directing a.c. and d.c. electric fields are critically reviewed. The principles involved when alignment is attempted by cooling from the melt in the presence of an electric field or by direct application of the field to a material in its liquid‐crystalline (LC) state are outlined, and the difficulties which may be encountered in practice are described and evaluated. An “electrical cleaning” method whereby the low‐frequency conductance losses in a sample may be reduced is described and is applied to LC polymer materials. Experimental dielectric data are presented and analysed for two LC polymers which contain azo‐groups in the side chains.
Polymers for electrical and optical data storage
Authors: Kämpf Günther , Freitag Dieter , Fengler Gerd , Sommer Klaus 
Published: April 2003

AbstractPolymers possess great significance in data storage technology. Taking as an example electrical and optical data storage, the state of development, properties required and opportunities for application of selected polymers are discussed, namely: (i) ferroelectric polymers with low switching voltages and extremely short switching times for electric data storage; and (ii) transparent polymers with low birefringence and high thermal stability for optical data storage.In the area of electrical data storage devices/memories, ferroelectric polymers have not been able to establish themselves up to now due to their long switching time and limited thermal stability. However, recent investigations show that suitable copolymers based on PVDF/TrFE copolymers in ultra‐thin layers can achieve switching times of ≤100 ns. Nevertheless, the limited thermal stability of PVDF/TrFE copolymers prevent them from being integrated into the usual manufacturing process for Si‐based data storage devices (D‐RAM resp. S‐RAM) and thereby frustrates the desired objective of producing nonvolatile random access memories (NV‐RAMs).In the area of optical data storage technology, polycarbonate (PC) has established itself due to its favorable combination of properties. Thus, audio compact disks (CDs) are manufactured exclusively of PC, while high‐flow PC types of high optical purity are clearly the preferred substrate material for optical data storage disks. The increasingly stringent requirements to be met in terms of lower birefringence and better thermal stability mean that the development of suitable modified or substituted polycarbonates is required. The development work being carried out worldwide in this area is reviewed here, and new suitable substituted polycarbonates with lower birefringence and significantly increased thermal stability up to glass temperatures of 238°C are presented.In addition, we deduce structure—property relationships for the above‐mentioned structurally modified polycarbonates, specifically considering rotation potentials along the polymer backbone.
The change of the superstructure of semicrystalline polymers during deformation: results from small‐angle scattering with synchrotron radiation
Authors: Wilke Wolfgang , Bratrich Michael , Heise Bernd , Peichel Gerhard 
Published: April 2003

AbstractThe change of the superstructure of different polyethylenes during uniaxial deformation is investigated. The method used is small‐angle scattering with synchrotron radiation. For branched polyethylene (Lupolen 1840D) the whole deformation range is analyzed. Beginning with superstructure of the lamellar cluster type, the superstructure partly disappears on a time scale of a few minutes and the fibrillar structure is built up. The degree of destruction and rebuilding depends on the drawing temperature. For very high molecular weight polyethylene (GUR) a reversible change of the superstructure at higher deformation ratios and at different temperatures is observed. The superstructure of (ethylene—hexene) copolymers (TIPELIN) at high draw ratios depends on the drawing temperature and is almost independent of the side group content. Interfibrillar microcracks parallel to the draw direction are produced in samples with a low side group content for draw ratios λ ≥ 1.5.
Mesomorphic and ferroelectric properties of FLCP/FLC binary mixtures
Authors: Dumon M. , Nguyen H. T. 
Published: April 2003

AbstractWe have prepared several ferroelectric polysiloxanes with two and three benzenic ring moieties. The siloxane backbone is favorable to ferroelectric S phase formation, and the chiral S phase is observed in all of the polymers. Some of the spontaneous polarizations are very high, more than 100 nC/cm2 (10−3 C/m2) and the response times are less than 1 ms near the I‐S or Sa–SS transition. Several binary mixtures between FLC copoly‐siloxanes and different low molar mass LC have been studied, and have shown the complete miscibility of these two components and richer mesomorphic sequences than for the polymers alone; for example, an N*–Sa sequence.
Electro‐optical properties of ferroelectric liquid crystalline polymers
Authors: Yuasa Kimihiro , Uchida Shunji , Sekiya Takashi , Hashimoto Kenji , Kawasaki Kenji 
Published: April 2003

AbstractFerroelectric liquid crystalline polymers (FLCPs) were synthesized. These ferroelectricities were confirmed directly by measuring polarization reversal currents and other electro‐optical properties. The smectic layer structure of FLCP was also studied. A chevron structure similar to that of low molecular weight FLC was observed even in an FLCP cell; but the zigzag defects were not so sharp, which means that it is easy to obtain a good orientation even in large‐area displays.
Polymeric liquid crystals: structural basis for ferroelectric and nonlinear optical properties
Authors: Zentel R. , Poths H. , Kremer F. , Schönfeld A. , Jungbauer D. , Twieg R. , Willson C. G. , Yoon D. 
Published: April 2003

AbstractThis paper describes the rational design and structure–property relations in three different types of polar LC polymers with interesting material properties, as follows. (i) Chiral LC polymers, which are functionalized with crosslinkable groups, can be converted into LC elastomers with chiral smectic C* phases. The mechanical orientability of these elastomers leads to new piezoelectric materials. (ii) The curing (dense crosslinking) of a polymer matrix provides one possibility of stabilizing the polar order of dye molecules, which is necessary for frequency doubling. Additionally, LC phases can help to stabilize this polar structure, which leads to large and stable nonlinear optical coefficients. (iii) Polymer analogous esterifications offer a convenient method for the synthesis of chiral smectic C* polymers with large ferrolectric polarizations.