bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maleic Anhydride Polyethylene Octene Elastomer Toughened Polyamide 6/Polypropylene Nanocomposites: Mechanical and Morphological Properties
Authors: Hassan Azman , Othman Norhayani , Wahit Mat Uzir , Wei Lim Jian , Rahmat Abdul Razak , Mohd Ishak Zainal Ariffin 
Published: June 2006

AbstractA series of polyamide 6/polypropylene (PA6/PP) blends and nanocomposites containing 4 wt% of organophilic modified montmorillonite (MMT) were designed and prepared by melt compounding followed by injection molding. Maleic anhydride polyethylene octene elastomer (POEgMAH) was used as impact modifier as well as compatibilizer in the blend system. Three weight ratios of PA6/PP blends were prepared i.e. 80:20, 70:30, and 60:40. The mechanical properties of PA6/PP blends and nanocomposite were studied through flexural and impact properties. Scanning electron microscopy (SEM) was used to study the microstructure. The incorporation of 10 wt% POEgMAH into PA6/PP blends significantly increased the toughness with a corresponding reduction in strength and stiffness. However, on further addition of 4 wt% organoclay, the strength and modulus increased but with a sacrifice in impact strength. It was also found that the mechanical properties are a function of blend ratio with 70:30 PA6/PP having the highest impact strength, both for blends and nanocomposites. The morphological study revealed that within the blend ratio studied, the higher the PA6 content, the finer were the POEgMAH particles.
Synthesis and Properties of Oligo‐/Polymers Based on a “Flexible” Swivel‐Cruciform Structure
Authors: Nehls Benjamin S. , Galbrecht Frank , Bilge Askin , Scherf Ullrich , Farrell Tony 
Published: June 2006

AbstractWe have introduced the concept of the so‐called swivel type cruciforms as a highly flexible tool to tune the molecular properties from amorphous to highly crystalline features. Simple alkoxy substituted binaphthyl building blocks have been introduced randomly into poly(9,9‐dioctylfluorene) (PFO) thereby suppressing the formation of side‐chain crystallization. On the other hand the all aryl penta‐thiophene based cruciform exhibited strong π–π interaction between the arms and gave one of the highest values reported to date for wet processed organic field effect transistors (OFETs) utilising oligothiophenes.
A Study on the Ballistic Performance of Composites
Authors: Faur‐Csukat Gabriella 
Published: June 2006

AbstractThe mechanical behaviour and ballistic performance of carbon, glass (E and S type), aramid and polyethylene fabric reinforced composites with different epoxy resins were studied. The specimens – produced by hand lay‐up method – were characterized by low velocity (Charpy and drop‐weight tests) and high velocity (two different calibre ballistic) impact tests. The energy absorption capacity of the composites was found to be strongly affected by the material properties of the reinforcing fiber, by the type of fabric structure and by the elasticity of resin.
Development and Analysis of New Filament Wound Composite Pipes Made of Glass Fiber Reinforced 3P Resin
Authors: Czél Gergely , Czigány Tibor 
Published: June 2006

AbstractFilament wound composite pressure pipes made of newly developed 3P, various hybrid and reference resin materials and glass fiber filaments were investigated. 3P resins consist of soluble silicates, polyisocyanates and other additives, they are flame and chemical resistant, and capable of curing under wet conditions. Tensile strengths, tensile moduli and effective moduli values obtained from ring stiffness tests were evaluated. Properties of pipe types made of new resin materials were compared to those made of reference resins. A special tensile specimen fabricating process and a cross sectional area calculating method was presented. The calculation method is capable of handling the geometric inaccuracies of specimen prefabrication steps e.g. cutting. Evaluated material properties were discussed by defining dimensionless performance factors. Pipes were classified according to these performance factors and the suitability of the new resin materials for composite pressure pipe manufacturing was established. The best newly developed matrix materials were the 16905 type vinylester‐3P hybrid and 16907 type vinylester‐urethane hybrid resins, because of their outstanding mechanical properties.
Sol‐Gel Transition and Equilibrium Shear Modulus of Poly(vinyl chloride) and Plasticizers
Authors: Semsarzadeh M. A. , Barikani S. M. 
Published: June 2006

AbstractThe elasticity of poly(vinyl chloride) gels with molecular weight distribution (Mw/Mn), of 2.16 have been studied in the region beyond their gel points. Dynamic storage modulus G′, and equilibrium gel shear modulus of elasticity Ge, at low frequencies (ω) have specific developments as a function of polymer concentrations c, and plasticizers. The scaling elasticity from Ge = kεz equation holds at different PVC plasticizer gels. The scaling exponent z, and constant k. ε is defined as the relative distance, ε = (|c − cg|)/cg, the calculated z = 2.45 ± 0.15. Furthermore, this analysis provides constant k with certain informations about the dependency of gel elasticity on the kind of plasticizer. Near the sol‐gel transition temperature T, Ge decreases rapidly with increasing temperature. The normalized moduli GeM/cRT, of the gels at different temperature, and/or c were dependent on the relative distance from the gelation point ε, and PVC and plasticizers concentration respectively. These results suggested mesh size of gel network near the gelation point for PVC with bis(2‐ethylhexyl) phthalate (DOP) or di‐n‐butyl sebacate (DBS) plasticizers that has been newly reported.
Effect of Temperature on Dynamic Physical Behavior of Poly(vinyl chloride) Gel Structure with Ester Plasticizers
Authors: Semsarzadeh M. A. , Barikani S. M. , Ansari M. 
Published: June 2006

AbstractDynamic viscoelastic properties of poly(vinyl chloride) (PVC)/bis(2‐ethylhexyl) phthalate (DOP) and PVC/di‐n‐butyl sebacate (DBS) gels with molecular weight distribution (Mw/Mn), of 2.16 and various polymer concentrations c, have been studied as a function of temperature. These PVC gels exhibited an elastic solid at room temperature T, and gradually became liquid (sol) with increasing temperature. The sol‐gel transition took place at a critical gel temperature at which the scaling law of G′(ω) ∼ G″(ω) ∝ ωn held, allowing an accurate determination of the critical gel temperature by means of the frequency ω independence of the loss tangent. In this study the scaling exponent n, was 0.75–0.77. This is in good agreement with the previous results observed at different temperatures and suggests the formation of a similar fractal structure of the PVC gels. The gel strength Sg, at the gel point increased with increasing PVC concentration. These results suggest a unique character and structure for the gel points of PVC‐plasticizers.
Kinetics and Morphology of an Epoxy Resin Modified with PEO‐PPO‐PEO Block Copolymers
Authors: de la Caba Koro , Larrañaga Maider , Eceiza Arantxa , Corcuera Maria Angeles , Mondragon Inñaki 
Published: June 2006

AbstractBlock copolymers are a special class of polymers having the ability to self‐assemble into nanoscale ordered structures which depend on molecular composition of the blocks. With the aim of studying the influence of copolymer composition, the kinetics of a 4,4′‐diaminodiphenylmethane‐cured diglycidyl ether of bisphenol‐A (DGEBA) epoxy system modified with a PEO‐PPO‐PEO block copolymers has been investigated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), taking into account the relation between blocks in the copolymer as well as different copolymer contents. DSC results show that the rate of cure reaction decreases when the copolymer is added, which can be attributed to the interaction between the hidroxyl groups of the growing epoxy thermoset and the ether groups of the block copolymer observed by FTIR. The experimental results obtained have been related to the morphologies observed by atomic force microscopy (AFM).
Preparation of a New Polymeric Surfactant for Emulsion Polymerization
Authors: Sarac Ayfer , Filiz Senkal B. , Yavuz Erdem , Gürsel Yesim Hepuzer 
Published: June 2006

AbstractThe stability of polymeric dispersions is a property of practical importance and hence, the search for an optimized strategy to equip polymer dispersions with sufficient stability is a matter of continuous research during the last years. The kernel is to reach a sufficient stability, as it is required during polymerization, conditioning, or storage and to allow coagulation or coalescence of particles when it is needed, such as during separation of polymer from latex or during film formation. In this study, the emulsion homopolymerization system containing vinyl acetate, potassium persulfate, new polymeric surfactant, NaHCO3 and water was studied in the classical glass emulsion polymerization reactor. The effects of new polymeric emulsifier on the physicochemical properties of obtained vinyl acetate latex properties were investigated depending on vinyl acetate percentage in homopolymerization.
Preparation of Aqueous Polyurethane Dispersions Using Aromatic Diisocyanate
Authors: Sugano Shunji , Chinwanitcharoen Charoen , Kanoh Shigeyoshi , Yamada Toshiro , Hayashi Shunichi , Tada Kaoru 
Published: June 2006

AbstractAqueous polyurethane dispersions were prepared by the reaction of hydroxyl‐terminated poly(ethylene adipate), ethylene glycol, dimethylol propionic acid and aromaic diisocyante, 4,4′‐diphenylmethane diisocyanate. The influence of molecular weight of oligoester and molar ratio between isocyanate and hydroxyl groups (NCO/OH) in the prepolymerization step were investigated. Molecular weight, particle size and particle size distribution were measured and compared. It was verified that the molecular weight increases with increasing in NCO/OH molar ratio. The results suggest that the hard segment content plays an important role in particle size and particle size distribution of the dispersions.
Synthesis and Characterization of Triblock Terpolymers with three Potentially Crystallisable Blocks: Polyethylene‐b‐poly(ethylene oxide)‐b‐poly(ε‐caprolactone)
Authors: Vivas M. , Contreras J. , López‐Carrasquero F. , Lorenzo A.T. , Arnal M.L. , Balsamo V. , Müller A.J. , Laredo E. , Schmalz H. , Abetz V. 
Published: June 2006

AbstractA first attempt was made to produce novel ABC triblock terpolymers with three potentially crystallisable blocks: polyethylene (PE), poly(ethylene oxide) (PEO), and poly(ε‐caprolactone) (PCL). Polybutadiene‐b‐poly(ethylene oxide) diblock copolymers were synthesized by living anionic polymerization. Then, a non‐catalyzed thermal polymerization of ε‐caprolactone from the hydroxyl end group of the PB‐b‐PEO diblock precursors was performed. Finally, hydrogenation by Wilkinson catalyst produced PE‐b‐PEO‐b‐PCL triblock terpolymers. Side reactions were detected that lead to the formation of undesired PCL‐b‐PEO diblock copolymers, however, these impurities were successfully removed by purification. A range of triblock terpolymers with PCL and PEO minor components were prepared. Topological restrictions on the PEO middle block prevented this block from crystallizing while the complex crystallization behavior of the PE and PCL blocks was documented by DSC and WAXS measurements.
Π‐Conjugated Helical Nano‐Columnar Polyacetylenes as Novel Color Controllable Materials
Authors: Tabata Masayoshi , Mawatari Yasuteru , Sone Takeyuki , Miyasaka Atsushi , Kai Huang , Orito Kazuhiko , Sadahiro Yoshikazu 
Published: June 2006

AbstractA series of p‐n‐alkoxyphenylacetylenes (pROPA)s (R: CnH2n+1, n = 1, 2, 4, 6, 8, 10, 12, and 14) was polymerized with [Rh(norbornadiene)Cl]2 catalyst in the presence of triethylamine to give stereoregular polyacetylenes, which colors of the resulting polymers were changed with increace of the carbon number of the alkyl side chains, i.e., yellow (n = 1∼6), orange (n = 8), red (n = 10), and dark red (n = 12, 14) along. Based on 1H NMR and laser Raman spectra, it was found that the main chain of these polymers was cis‐forms. Wide‐angle X‐ray diffraction (XRD) analysis indicated that yellow polymers were almost amorphous. In the case of the orange polymer, crystallinity, i.e., columnar content, was increased. Red and dark red polymers consisted largely of the columnar. It was concluded that colors of these polymers were strongly correlated with their columnar content. Therefore, the columnar of these stereoregular polyacetylenes can be considered as helical self‐assembly π‐conjugated , i.e., color controllable material.
Aliphatic Polyesters for Advanced Technologies – Structural Characterization of Biopolyesters with the Aid of Mass Spectrometry
Authors: Adamus Grażyna 
Published: June 2006

AbstractApplication of the ESI‐ mass spectrometry technique for the structural studies of biopoliesters is reported. The structural studies were performed on two selected commercially available biopolyesters i.e. poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBH), contained up to 87% of PHB repeat units, with the aid of ESI‐MS analysis of the respective low molar mass oligomers. The molecular architecture of individual macromolecules, including the chemical structure of the end groups, composition and sequence distribution were determined based on mass‐resolved signals of ESI‐mass spectra of PHBH and PHBV oligomers. The general utility of MS characterization of biopoliester macromolecules at the molecular level has been demonstrated and supported by NMR analysis.
Characterization of Plasma‐Polymerized 4‐vinyl Pyridine with Silver Nanoparticles on Poly(ethylene terephthalate) Film for Anti‐Microbial Properties
Authors: Jiang Juan , Winther‐Jensen Bjørn , Kjær Erik M. 
Published: June 2006

Abstract4‐vinyl pyridine was polymerized on poly(ethylene terephthalate) (PET) film by using lower energy pulsed AC plasma under low pressure in Ar atmosphere. The plasma polymerized coating was characterized by ATR Fourier transform infrared (FT‐IR), scanning electron microscopy (SEM), field emission scanning electron microscopy (FE‐SEM), atomic force microscopy (AFM) and X‐ray photoelectron spectroscopy (XPS). Different thicknesses of poly(4‐vinyl pyridine) coating under different plasma polymerization conditions were studied. Silver nanoparticles with diameter around 50nm deposit were precipitated on the poly(4‐vinyl pyridine) coating by UV irradiation in Silver nitride water solution, in order to enhance the anti‐microbial properties. Different kinds of modified PET films were tested for anti‐microbial properties against yeast (Debaryomyces hansenii) by using microbiological analyser µ‐4200 and direct microscopic count method.
Surface Structure and Stereocomplex Formation of Enantiomeric Polylactide Blends Using Poly(dimethyl siloxane) as a Probe Polymer
Authors: Lee Jin‐Kook , Kim Mi‐Ra , Lee Hyun‐Jeong , Chung Ildoo , Lim Kwon Taek , Jeon Sangik , Lee Won‐Ki 
Published: June 2006

AbstractIn the stereocomplex between enantiomeric poly(l‐lactide) (l‐PLA) and poly(d‐lactide), crystallites formed as a result of stereocomplexation, equimolar l‐ and d‐lactide unit sequences are packed side by side. The stereocomplex exhibits a melting temperature higher by about 50 °C than that of each homopolymer. In this study, we attempt to obtain further insight into the stereocomplex‐induced surface structure of enantiomeric PLA blend films. The design of the blend systems is based on principles of surface segregation of multicomponent polymeric systems with a low surface energy, triblock copolymer (l‐PLA‐b‐PDMS‐b‐l‐PLA) of l‐PLA and poly‐(dimethyl siloxane). (l‐PLA‐b‐PDMS‐b‐l‐PLA/l‐PLA) blend films showed the surface segregation of PDMS, regardless of blend composition while the surface composition of PDMS in the (l‐PLA‐b‐PDMS‐b‐l‐PLA/d‐PLA) blend films was strongly depended on blend composition or a degree of complexation. These results are likely due to strong interaction between d‐ and l‐lactide unit sequences, which prevents the surface segregation of PDMS.
Acetazolamide acts directly on the human skeletal muscle chloride channel
Authors: Eguchi Hiroto , Tsujino Akira , Kaibara Muneshige , Hayashi Hideki , Shirabe Susumu , Taniyama Kohtaro , Eguchi Katsumi 
Published: June 2006

AbstractAcetazolamide, a carbonic anhydrase inhibitor, is used empirically in neuromuscular diseases with episodic ataxia, weakness, and myotonia, although not all of the mechanisms responsible for its therapeutic effects are understood. To elucidate whether acetazolamide acts directly on the human skeletal muscle voltage‐gated chloride channel (ClC‐1), which is associated with myotonia, we evaluated the effects of acetazolamide on ClC‐1 expressed in cultured mammalian cells, using whole‐cell recording. Acetazolamide significantly shifted the voltage dependency of the open probability (Po) toward negative potentials in a dose‐dependent manner, resulting in an increase of chloride conductance at voltages near the resting membrane potential. This effect was attenuated when using a pipette solution containing 30 mmol/L Hepes. These results suggest that acetazolamide can influence the voltage‐dependent opening gate of ClC‐1 through a mechanism related to intracellular acidification by inhibiting carbonic anhydrase, and that the therapeutic effects of acetazolamide in neuromuscular diseases may be mediated by activation of ClC‐1. Muscle Nerve, 2006
Passive mechanical properties of maturing extensor digitorum longus are not affected by lack of dystrophin
Authors: Wolff Andrew V. , Niday Ashley K. , Voelker Kevin A. , Call Jarrod A. , Evans Nicholas P. , Granata Kevin P. , Grange Robert W. 
Published: June 2006

AbstractMechanical weakness of skeletal muscle is thought to contribute to onset and early progression of Duchenne muscular dystrophy, but this has not been systematically assessed. The purpose of this study was to determine in mice: (1) whether the passive mechanical properties of maturing dystrophic (mdx) muscles were different from control; and (2) if different, the time during maturation when these properties change. Prior to and following the overt onset of the dystrophic process (14–35 days), control and dystrophic extensor digitorum longus (EDL) muscles were subjected to two passive stretch protocols in vitro (5% strain at instantaneous and 1.5 L0/s strain rates). Force profiles were fit to a viscoelastic muscle model to determine stiffness and damping. The mdx and control EDL muscles exhibited similar passive mechanical properties at each age, suggesting a functional threshold for dystrophic muscle below which damage may be minimized. Determining this threshold may have important clinical implications for treatments of muscular dystrophy involving physical activity. Muscle Nerve, 2006
Long‐term administration of pirfenidone improves cardiac function inmdxmice
Authors: Van Erp Christel , Irwin Nicole G. , Hoey Andrew J. 
Published: June 2006

AbstractDuchenne muscular dystrophy, an X‐linked recessive neuromuscular disorder due to lack of the protein dystrophin, manifests as progressive muscle degeneration and cardiomyopathy with increased fibrosis. The exact mechanisms involved in fibrosis are unknown, but a cytokine, transforming growth factor‐beta (TGF‐β), is a likely mediator. This study tested whether the TGF‐β antagonist, pirfenidone, could reduce cardiac fibrosis. Eight‐month‐oldmdxmice were treated for 7 months with 0.4%, 0.8%, and 1.2% pirfenidone in drinking water; untreated water was given to controlmdxand C57 mice. Mice treated with 0.8% and 1.2% pirfendone had lowered cardiac TGF‐β mRNA and improved in vitro cardiac contractility (P< 0.05) to levels consistent with C57 mice, yet without a change in cardiac stiffness or fibrosis. These results show that the TGF‐β antagonist, pirfenidone, can improve cardiac function inmdxmice, potentially providing a new avenue for developing cardiac therapies for patients with Duchenne muscular dystrophy. Muscle Nerve, 2006
Isaacs' syndrome: Clinical and electrophysiological response to gabapentin
Authors: Dhand Upinder K. 
Published: June 2006

AbstractA patient with Isaacs' syndrome had generalized muscle spasms, twitching, and progressive muscle stiffness for 21 years. Electrodiagnostic study showed continuous spontaneous motor‐unit activity and the presence of M‐wave afterdischarges. He responded dramatically to treatment with carbamazepine but developed a drug rash; his treatment was changed to gabapentin with continued improvement. Subsequent nerve conduction studies showed decreased amplitude and later an absence of M‐wave afterdischarges. Gabapentin thus appears to be an effective treatment for Isaacs' syndrome. Muscle Nerve, 2006
Influences of ventilation on maximal isometric force of the finger flexors
Authors: Li Sheng , Laskin James J. 
Published: June 2006

AbstractForce production may be influenced by the phase of ventilation during which force is exerted. To examine the potential influences of ventilation on variability in maximal force measurements, we recorded peak isometric forces of the finger flexors during normal breathing, forced inspiration, forced expiration, and the Valsalva maneuver in 14 healthy adult subjects. The peak force increased significantly from forced inspiration to forced expiration (about 10%). Both forced expiration and inspiration resulted in increases in the flexor/extensor cocontraction ratio, whereas the Valsalva maneuver had no significant effects on maximal force or cocontraction ratio. Thus, this study clearly demonstrates the effects of ventilation on maximal finger force‐generating capability. Ventilation needs to be controlled for accurate assessments of maximal force. Muscle Nerve, 2006
Size and shape evolution of pores in a viscoplastic matrix under compression
Authors: Berli M. , Accorsi M. L. , Or D. 
Published: June 2006

AbstractThe frequent use of soils and earth materials for hydraulic capping and for geo‐environmental waste containment motivated our interest in detailed modelling of changes in size and shape of macro‐pores to establish links between soil mechanical behaviour and concurrent changes in hydraulic and transport properties. The objective of this study was to use finite element analysis (FEA) to test and extend previous analytical solutions proposed by the authors describing deformation of a single macro‐pore embedded in linear viscoplastic soil material subjected to anisotropic remote stress. The FEA enables to consider more complex pore geometries and provides a detailed picture of matrix yield behaviour to explain shortcomings of approximate analytical solutions. Finite element and analytical calculations agreed very well for linear viscous as well as for viscoplastic materials, only limited for the case of isotropic remote stress due to the simplifications of the analytical model related to patterns and onset of matrix‐yielding behaviour. FEA calculations were compared with experimental data obtained from a compaction experiment in which pore deformation within a uniform modelling clay sample was monitored using CAT scanning. FEA predictions based on independently measured material properties and initial pore geometry provided an excellent match with experimentally determined evolution of pore size and shape hence lending credence to the potential use of FEA for more complex pore geometries and eventually connect macro‐pore deformation with hydraulic properties. Copyright © 2006 John Wiley & Sons, Ltd.