bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water‐Soluble AmphiphilicO‐(Carboxymethyl)cellulose Derivatives – Synthesis and Properties
Authors: Sroková Iva , Tomanová Vladimíra , Ebringerová Anna , Malovíková Anna , Heinze Thomas 
Published: February 2004

AbstractSummary:Water‐soluble, partially hydrophobized derivatives ofO‐(carboxymethyl)cellulose (CMC) were prepared by esterification of CMC in its ‘gel suspension’ form. The classical esterification method (A) using stearoyl chloride/pyridine as well as two unconventional methods based on reaction with mixed anhydrides (B) and transesterification with vinyl laurate (C) respectively, were compared in terms of the structural, molecular and performance properties of the obtained derivatives. The classical esterification and method B yielded water‐soluble simple fatty acid esters, whereas mixed acetic‐fatty acid esters were obtained by method C. In all cases, molecular degradation of CMC was observed.1H and13C NMR spectroscopy of the acetyl‐lauroyl derivatives of CMC with a degree of esterificationDSEof 0.20 indicated a prevalence of the lauroyl groups (DSAc:DSLa = 0.03:0.17). Most of the water‐soluble derivatives exhibited excellent emulsifying efficiency. They represent polysaccharide‐based surfactants with effective anti‐redeposition properties as well as good washing power. Suitable derivatives can be prepared under mild reaction conditions by both unconventional methods which implies that they have potential as substitutes for the expensive and invasive conventional method.Preparation of CMC derivatives.magnified imagePreparation of CMC derivatives.
Dynamic Mechanical Properties of Poly(propylene) Blends with Poly[ethylene‐co‐(methyl acrylate)]
Authors: Genovese Antonietta , Shanks Robert A. 
Published: February 2004

AbstractSummary: Blends of poly(propylene) (PP) were prepared with poly[ethylene‐co‐(methyl acrylate)] (EMA) having 9.0 and 21.5% methyl acrylate comonomer. A similar series of blends were compatibilized by using maleic anhydride grafted PP. The morphology and mechanical properties of the blends were investigated using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) in tensile mode. The DMA method and conditions were optimized for polymer film specimens and are discussed in the experimental section. The DSC results showed separate melting that is indicative of phase‐separated blends, analogous to other PP‐polyethylene blends but with the added polarity of methyl acrylate pendant side groups that may be beneficial for chemical resistance. Heterogeneous nucleation of PP was decreased in the blends because of migration of nuclei into the more polar EMA phase. The crystallinity and peak‐melting temperature did not vary significantly, although the width of the melting endotherm increased in the blends indicating a change had occurred to the crystals. DMA analysis showed the crystal‐crystal slip transition $T_{\rm \alpha }^*$ and glass transition (Tg) for PP as well as a Tg of the EMA copolymer occurring chronologically toward lower temperatures. The storage modulus of PP and the blends was generally greater with annealing at 150 °C compared with isothermal crystallization at 130 °C. The storage modulus of the blends for isothermally crystallized PP increased with 5% EMA, then decreased for higher amounts of EMA. Annealing caused a decrease with increasing copolymer content. The extent of the trend was greater for the compatibilized blends. The Tg of the blends varied over a small range, although this change was less for the compatibilized blends.Storage modulus for PP and EMA9.0 blends annealed at 150 °C.magnified imageStorage modulus for PP and EMA9.0 blends annealed at 150 °C.
Preparation and Characterization of Chitosan‐Gellan Hybrid Capsules Formed by Self‐Assembly at an Aqueous Solution Interface
Authors: Ohkawa Kousaku , Kitagawa Takeshi , Yamamoto Hiroyuki 
Published: February 2004

AbstractSummary: True spherical capsules are formed by electrostatic polysaccharide interaction between chitosan and gellan gum via polyion complex (PIC) formation in aqueous solutions. Dropwise addition of a chitosan solution into the gellan solution gave spherical capsules whose outside surface was gellan and whose inside was chitosan (chitosanin‐gellanout capsule). Conversely, the addition of gellan into chitosan yields chitosanout‐gellanin capsules. SEM observation revealed a fibrous network spreading along the capsule membrane of the chitosanin‐gellanout capsule. The releasing properties of the capsules were examined using low molecular weight substances and high molecular weight proteins. For low molecular weight substances, the releasing kinetics were affected by the attractive and repulsive interactions between the substances and the inside component of the capsule. The molecular weight of the encapsulated substances also affects the releasing kinetics. These results, together with a simple preparation procedure, indicate the applicability of chitosan‐gellan capsules as drug‐carrier materials having a controlling release mechanism. As an application example, preparation of an actually eatable artificial roe was also described.Illustrative drawing of PIC capsule formation.magnified imageIllustrative drawing of PIC capsule formation.
Improvement of Chromatic Aberration of the Plastic Rod‐Lens Array, 2
Authors: Uozu Yoshihiro , Hirota Norifumi , Horie Kazuyuki 
Published: February 2004

AbstractSummary: We propose in this paper a new plastic rod‐lens with low chromatic aberration. Since a plastic rod‐lens has a parabolic refractive index distribution, it usually also shows a distribution of Abbe number. This Abbe number distribution is thought to cause the chromatic aberration of the plastic rod‐lens array. We have studied novel materials for a new plastic rod‐lens with low chromatic aberration and have provided new transparent polymer blends consisting of two polymers with different refractive indices and with almost equal Abbe numbers by using a fabrication process based on photopolymerization of methacrylate monomer(s) in the presence of other methacrylic polymers. The process can give new transparent polymer blends which cannot be formed using conventional techniques for polymer blend formation. In this work, tricyclo[5,2,1,02,6]deca‐8‐yl methacrylate is used as a high refractive index monomer and tert‐butyl methacrylate is used as a low refractive index one. By using polymer blends including these monomer units, we have created a plastic rod‐lens with lower chromatic aberration.Molecular structures of comonomers in the study.magnified imageMolecular structures of comonomers in the study.
Synthesis and Characterisation of Anhydride‐Cured Epoxy Nanocomposites Containing Layered Silicates Modified with Phenolic Alkylimidazolineamide Cations
Authors: Fröhlich Jörg , Golombowski Dietmar , Thomann Ralf , Mülhaupt Rolf 
Published: February 2004

AbstractSummary: Phenolic alkylimidazolineamides were prepared and applied as modifiers in order to render layered silicates organophilic and to prepare polymeric nanocomposites. The imidazolineamine, 2‐{2‐[heptadec‐8‐enyl]‐4,5‐dihydro‐1‐imidazol‐1‐yl}‐1‐ethaneamine (IA), was reacted in bulk with one of the two phenolic compounds, ethyl 4‐hydroxybenzoate (P) or methyl 3‐[3,5‐di(tert‐butyl)‐4‐hydroxyphenyl]propionate (HP), which is an intermediate for antioxidants, to prepare the two phenolic imidazolineamides, PIA and HPIA. During protonation in water, both phenolic imadazolineamides were used successfully to exchange interlayer sodium cations of sodium bentonite and fluorohectorite, thus producing organophilic layered silicates with an increased interlayer distance of around 3.3 nm. The new phenolic organophilic layered silicates represent a novel class of phenolic organic/inorganic hybrid materials. They were applied as fillers in hexahydrophthalic anhydride‐cured bisphenol‐A diglycidyl ether (BADGE). Thermal analysis (DSC), transmission electron microscopy (TEM), wide angle X‐ray scattering (WAXS), and mechanical tests were used to evaluate the thermal, mechanical, and morphological properties. Although fracture toughness, measured as the stress intensity factor, KIc, and the energy release rate, GIc, increased by around 50% with increasing silicate content without sacrificing glass temperature, both tensile strength and Young's modulus increased only marginally. Low matrix reinforcement was attributed to inadequate compatibility matching, as evidenced by the slightly lower interlayer distances of the layered silicates encapsulated in the epoxy matrix.Representative TEM micrographs of the sample ER‐bent‐PIA/10.magnified imageRepresentative TEM micrographs of the sample ER‐bent‐PIA/10.
Brittle‐Ductile Transition and Toughening Mechanism in POM/TPU/CaCO3 Ternary Composites
Authors: Gao Xiaoling , Qu Cheng , Zhang Qin , Peng Ya , Fu Qiang 
Published: February 2004

AbstractSummary: Polyoxymethylene (POM)/elastomer/filler ternary composites were prepared, in which thermoplastic polyurethane(TPU) and an inorganic filler, CaCO3, were used to achieve balanced mechanical properties of POM. A two‐step processing method, in which the elastomer and the filler were mixed to a masterbatch first and then the masterbatch was melt‐blended with pure POM, was used to obtain a core‐shell microstructure with CaCO3 covered by TPU. A brittle‐ductile transition phenomenon was observed with increasing TPU content for this ternary system. To better understand the toughening mechanism, we investigated the fractured surface, interparticle distance, and the spherulite size of POM as function of the TPU and CaCO3 content. The critical TPU content depended on not only the content of CaCO3, but also the size of CaCO3 particles. The observed brittle‐ductile transition was discussed based on the crystallinity and spherulite size of POM as well as Wu's critical interparticle distance theory. The results showed that the impact strength of POM/TPU/CaCO3 ternary system depends on a critical, interparticle distance, which varies from one system to another. The dependence of the impact strength on the spherulite size was considered for the first time, and a single curve was constructed. A critical spherulite size of 40 micron was found, at which brittle‐ductile transition occurs, regardless of the TPU and CaCO3 content or the size of CaCO3 particles. Our results indicate that the spherulite size of POM indeed plays a role in determining the toughness, and must be considered when discussing the toughening mechanism.Izod impact strength vs. the crystal size for POM/TPU blends and POM/TPU/CaCO3 ternary composites.magnified imageIzod impact strength vs. the crystal size for POM/TPU blends and POM/TPU/CaCO3 ternary composites.
The Solid State Postcondensation of PET, 1
Authors: Gantillon Barbara , Spitz Roger , McKenna Timothy F. 
Published: February 2004

AbstractSummary: A review of the processes underlying the solid state postcondensation of poly(ethylene terephthalate) (PET) is presented. Fundamental aspects of the reactions are treated, and it is shown that the rate of polycondensation in the solid state depends on the relative rates of two types of diffusion. On the one hand, the diffusion of reaction by‐products (physical diffusion) controls the rate of the forward reactions. And on the other hand the diffusion of end‐groups (chemical diffusion) allows the reaction to proceed.The transesterification of BHET to form PET.magnified imageThe transesterification of BHET to form PET.
The Solid State Postcondensation of PET, 2
Authors: Gantillon Barbara , Spitz Roger , McKenna Timothy F. 
Published: February 2004

AbstractSummary: A process for the solid state polycondensation of PET is proposed. It is shown that by correctly choosing the prepolymerisation conditions it is possible to crystallise the product and to directly polymerise it in a dispersed phase. This process is significantly faster than the “standard” PET processes, and allows one to obtain high molecular weights directly from a prepolymer without the need to use an intermediate solution polymerisation step.Reactor set‐up for precursor preparation and dispersed phase prepolymerisation.magnified imageReactor set‐up for precursor preparation and dispersed phase prepolymerisation.
The Solid State Postcondensation of PET, 3
Authors: Gantillon Barbara , Spitz Roger , McKenna Timothy F. 
Published: February 2004

AbstractSummary: It was demonstrated that it is possible to produce prepolymers with a number‐average degree of polymerisation on the order of 5–40 directly in a liquid‐liquid dispersion in less than three hours. It was also shown that prepolymers made via this route and rapidly crystallised by the addition of a dispersant at ambient temperature are more porous than prepolymers made in an industrial liquid melt process.SEM micrograph of prepolymers pLL‐PTA with \overline {DP} _{\rm n} = 28, dp ∈ 63–125 μm.magnified imageSEM micrograph of prepolymers pLL‐PTA with \overline {DP} _{\rm n} = 28, dp ∈ 63–125 μm.
The Solid State Postcondensation of PET, 4
Authors: Gantillon Barbara , Spitz Roger , Lepage Jean‐Luc , McKenna Timothy F. 
Published: February 2004

AbstractSummary: A new method of polymerising PET in the solid state is proposed in either a gas phase reactor, or in hydrocarbon dispersion. It is shown that the reaction can be carried out efficiently at temperatures on the order of 200–240 °C directly from a prepolymer without the need for a melt phase step. It is shown that the crystal structure of the prepolymer plays a determining role in the kinetics of the SSP reaction.Schema of the reactor used for gas phase SSP.magnified imageSchema of the reactor used for gas phase SSP.
Polyolefins with Long Chain Branches Made with Single‐Site Coordination Catalysts: A Review of Mathematical Modeling Techniques for Polymer Microstructure
Authors: Soares João B. P. 
Published: February 2004

AbstractSummary: Single‐site coordination polymerization catalysts are considered one of the most important developments on the technology of olefin polymerization during the last two decades. Among the several new capabilities of these catalysts is the ability to produce polymer molecules having narrow molecular weight distribution and long chain branches. These advances in polymer synthesis have stimulated the development of mathematical models to describe and predict several features of their molecular architectures. Many modeling techniques have been used for this purpose, including instantaneous distributions, population balances, the method of moments, and Monte Carlo simulations. This article reviews the mathematical models developed over the last decade to quantify the microstructure of polymers made with single‐site catalysts with special emphasis on the mechanism of long chain branch formation by terminal branching.
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Cover Picture: Macromol. Mater. Eng. 1/2004
Authors: Uozu Yoshihiro , Hirota Norifumi , Horie Kazuyuki 
Published: February 2004

Cover: Plastic rod‐lens arrays have been limitedly applied to white/black facsimiles and scanners because of their large chromatic aberration. Plastic rod‐lens with lower chromatic aberration can be realized by using new transparent polymer blends with a small dispersion of Abbe numbers.Further details can be found in the Full Paper by Y. Uozu,* N. Hirota, and K. Horie on page 56.
Homo‐ and Copolymerization of Butadiene Catalyzed by an Bis(imino)pyridyl Vanadium Complex
Authors: Colamarco Elena , Milione Stefano , Cuomo Cinzia , Grassi Alfonso 
Published: February 2004

AbstractSummary: The bis(imino)pyridyl vanadium(III) complex [VCl3{2,6‐bis[(2,6‐iPr2C6H3)NC(Me)]2(C5H3N)}] activated with different aluminium cocatalysts (AlEt2Cl, Al2Et3Cl3, MAO) promotes chemoselective 1,4‐polymerization of butadiene with activity values higher than classical vanadium‐chloride‐based catalysts. The polymer structure depends on the nature of the cocatalyst employed. The MAO‐activated complex was also found to be active in ethylene‐butadiene copolymerization, producing copolymers with up to 45 mol‐% of trans‐1,4‐butadiene. Crystalline polyethylene and trans‐1,4‐poly(butadiene) segments were detected in these copolymers by DSC and 13C NMR spectroscopy.image
New Positive‐Type Photoresists Based on Enzymatically Synthesized Polyphenols
Authors: Kadota Joji , Fukuoka Tokuma , Uyama Hiroshi , Hasegawa Kiichi , Kobayashi Shiro 
Published: February 2004

AbstractSummary: New positive‐type photoresist systems based on enzymatically synthesized polyphenols have been developed. The photoresist thin film consisting of the polyphenol and a diazonaphthoquinone derivative was prepared on copperfoil‐coated epoxy resins and exposed to UV light with different doses. The polyphenols from the bisphenol monomers exhibited high photosensitivity, comparable with a conventional cresol novolac. The sensitivity could be controlled by changing the structure of the polyphenols. Furthermore, the present photoresist showed excellent etching resistance.Characteristic exposure curves of poly(1)/DNQ and poly(5)/DNQ (both 70:30 wt.‐%) with different phenylene unit contents.imageCharacteristic exposure curves of poly(1)/DNQ and poly(5)/DNQ (both 70:30 wt.‐%) with different phenylene unit contents.
Block Copolymers in Emulsion and Dispersion Polymerization
Authors: Riess Gérard , Labbe Clorinthe 
Published: February 2004

AbstractSummary:This article deals with recent progress including the authors' work concerning the application of block copolymers as polymeric surfactants in heterophase polymerizations. The synthesis methods for preparing block copolymers by emulsion and dispersion techniques are outlined, with emphasis on recently developed controlled free radical polymerizations in aqueous media. Specific characteristics of amphiphilic block copolymers are described, for example, micellization and emulsifying effects. A general overview of emulsion and dispersion polymerization in an aqueous and organic medium with ionic and nonionic block copolymers is presented for the preparation of electrosteric and sterically stabilized latex particles. Typical examples of microemulsion, miniemulsion, oil‐in‐oil emulsion, and micellar polymerizations are provided. Current and potential developments of so‐called “hairy latexes”, inverse‐, multiple‐, and solid emulsions, as well as of nonaqueous polymeric dispersions are also discussed.PS foam obtained by free radical polymerization of water‐in‐styrene, stabilized with a PS–PEO diblock copolymer.imagePS foam obtained by free radical polymerization of water‐in‐styrene, stabilized with a PS–PEO diblock copolymer.
Polyurethanes with Pendant Hydroxyl Groups: Synthesis and Characterization
Authors: Ubaghs Luc , Fricke Nicole , Keul Helmut , Höcker Hartwig 
Published: February 2004

AbstractCommunication: Phenoxycarbonyloxymethyl ethylene carbonate 4 was synthesized from glycerol carbonate and phenyl chloroformate. Polyurethanes with pendant hydroxyl groups were obtained from polycondensation reactions of this AA* monomer with diamines. These polymers contain primary as well as secondary hydroxyl groups. The obtained polyurethanes are amorphous materials. The glass transition temperature decreases with increasing number of methylene groups between the urethane groups.As the number of methylene groups increases between the urethane groups, the glass transition temperature of the polymer decreases.magnified imageAs the number of methylene groups increases between the urethane groups, the glass transition temperature of the polymer decreases.
Novel Mechanism for Layered Silicate Clay Intercalation by Poly(propylene oxide)‐Segmented Carboxylic Acid
Authors: Lin Jiang‐Jen , Chang Yu‐Chung , Cheng I‐Jein 
Published: February 2004

AbstractSummary: Poly(propylene oxide)‐amidoacids were used to intercalate montmorillonite clay to afford organoclays with an X‐ray basal spacing as wide as 81 Å. Differing from the ionic exchange between quaternary ammonium salts and the metal ions in clays, the intercalation mechanism involves a beta‐amidoacid chelation with sodium ions in the silicate interlayer confinement. With the end groups tethered on the silicate surface, the hydrophobic poly(propylene oxide)‐backbones self‐aggregate and consequently widen the interlayer space between neighboring silicate plates.Postulated structure of the chelation of sodium ions by the poly(propylene oxide)‐amido acid.magnified imagePostulated structure of the chelation of sodium ions by the poly(propylene oxide)‐amido acid.
Polymer Architectures Consisting of Rotating Fibers Prepared by Photopolymerization in a Cholesteric Phase
Authors: Kihara Hideyuki , Miura Toshiaki , Kishi Ryoichi 
Published: February 2004

AbstractSummary: Hydrogen‐bonded polymer films consisting of fine, extended fibers were prepared by photopolymerization of an acrylate monomer containing a benzoic acid group in the fingerprint or Grandjean textures of a cholesteric liquid‐crystalline mixture. Scanning electron microscopy and circular dichroism spectroscopy revealed that the fibers, measuring about 400 nm in diameter, formed helical superstructures and that their helical axes corresponded to the cholesteric helical axes that existed in the LC mixture before photopolymerization.SEM image of a polymer film.imageSEM image of a polymer film.
Depth Profiling by AFM Nanoindentations and Micro‐FTIR Spectroscopy for the Study of Polymer Ageing
Authors: Mailhot Bénédicte , Bussière Pierre‐Olivier , Rivaton Agnès , Morlat‐Thérias Sandrine , Gardette Jean‐Luc 
Published: February 2004

AbstractSummary: A method of depth profiling by AFM nanoindentations is developed for the characterisation of the heterogeneity of the mechanical properties of oxidised polymers. An increase or a decrease of the sample stiffness is measured close to the surface. A comparison with micro‐FTIR profiles and a knowledge of the photooxidation mechanism permit an interpretation of the chemical and physical changes and give new insights into the understanding of the ageing behaviour.Photooxidation profile of a TMPC film measured by AFM (•) and by micro‐FTIR (♦) after irradiation.imagePhotooxidation profile of a TMPC film measured by AFM (•) and by micro‐FTIR (♦) after irradiation.
Acrylic, Elastomeric, Particle‐Dispersed Epoxy‐Clay Hybrid Nanocomposites: Mechanical Properties
Authors: Balakrishnan Subramanian , Raghavan Dharmaraj 
Published: February 2004

AbstractSummary: Nanocomposites were formulated by curing a sonicated mixture of epoxy resin, C18 clay, and acrylic rubber dispersants. At 5.5 phr (parts per hundred) organoclay loading and a rubber concentration of 15 phr, the tensile‐failure strain of the nanocomposite was found to be higher than that of epoxy nanocomposite, rubber‐dispersed epoxy, and pristine epoxy. A plausible mechanism for improvement of the failure strain of nanocomposites is proposed.Stress strain curves of filled and unfilled epoxy specimen.magnified imageStress strain curves of filled and unfilled epoxy specimen.
Phenoxy–Ether Ligated Ti Complexes for the Polymerization of Ethylene
Authors: Suzuki Yasuhiko , Inoue Yoshihisa , Tanaka Hidetsugu , Fujita Terunori 
Published: February 2004

AbstractSummary: Bis(phenoxy–ether) Ti complexes were investigated as ethylene polymerization catalysts. The complexes, combined with iBu3Al/Ph3CB(C6F5)4 or methylaluminoxane (MAO) cocatalysts, can be highly active single‐site catalysts, which display activities ( turnover frequency, max. 2 065 min−1) comparable with that of a highly active bis(phenoxy–imine) Ti complex/MAO system, and provide very high molecular weight polyethylenes ($\overline M _{\rm v}$ 2 040 000–5 420 000) at 25 °C under atmospheric pressure.Synthesis of polyethylene using bis(phenoxy–ether) Ti complexes, an example of which is shown.magnified imageSynthesis of polyethylene using bis(phenoxy–ether) Ti complexes, an example of which is shown.