bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular modeling of polymers, 14 quantitative structure‐property relationship analyses of multicomponent systems containing polymers
Authors: Hopfinger A. J. , Koehler M. G. , Rogers David 
Published: March 2011

AbstractOne general class of polymer modeling applications involves materials which are large, in terms of molecular degrees of freedom, and poorly defined in terms of composition and morphology. Such materials are often multicomponent with respect to number of distinct polymers, fillers, additives, etc. Two obstacles limit the modeling of these materials. First, one normally does not have any idea about the key physicochemical molecular properties governing the system. Second, the functional dependence of the target properties of the material upon the key physicochemical molecular properties is usually totally unknown. Torsion angle unit (TAU) theory, a molecular decomposition technique, permits an arbitrarily large number of physicochemical properties to be computed in an open‐ended fashion, and thus addresses the first problem. Genetic function approximation (GFA) analysis tackles the second problem by efficiently exploring any desired number of functional relationships between target properties and physicochemical molecular properties. Case studies of (TAU theory)‐(GFA analysis) applications to estimate glass, Tg, and crystal‐melt, Tm, transition temperatures will be described.
Molecular interactions at the interface in blends of ester groups‐functionalized polyolefins
Authors: Aglietto M. , Benedetti E. , Ruggeri G. , Ciardelli F. , Pracella M. , D'Alessio A. 
Published: March 2011

AbstractDue to the apolarity of the aliphatic backbones, unmodified polyolefins are scarcely miscible with most of other polymers. The functionalization of preformed polyolefins is a way which has been successfully followed to improve the polymer miscibility.The functionalization of linear low density polyethylene (LLDPE) and ethylene‐propylene copolymers (EP), with diethyl maleate (DEM) and dicumyl peroxide (DCP) as radical initiator, gives products containing up to 2–5 mol % of well defined functional groups (2‐diethyl succinate).Intermolecular interactions of these functional groups are characterized by comparison with suitable low‐molecular‐weight structural models in the presence of different solvents containing acidic hydrogen atoms.On the basis of these indication evidences of interface molecular interactions in blends with halogenated polymers are described between the functionalized polyolefins and poly(vinyl chloride) (PVC), poly(vinylidene fluoride) (PVDF) or vinylidene fluoride‐hexafluoropropene copolymer obtained in semiindustrial Brabender mixers.It is shown that a smooth functionalization of the polyolefins can modify the phase behaviour and structure of these systems. The FT‐IR microanalysis supports the occurrence of partial miscibility phenomena which can be accounted for by specific intermolecular interactions involving the inserted functional groups and occurring mainly at the interfaces between domains of polyolefins and of the halogen‐containing polymers.
Structural analysis of polysaccharides and polysaccharide derivatives
Authors: Mischnick Petra 
Published: March 2011

AbstractThe general strategies and methods applied in the analysis of the primary structure of polysaccharides and derivatives are shortly lined out. Methods involving complete degradation of the polysaccharide are discussed in more detail. Advantages of the reductive‐cleavage method compared to classical methylation analysis are illustrated by giving some examples of application.
NMR Studies on the structure of cellulose. 2‐dimensional solid state NMR approach
Authors: Erata Tomoki , Shikano Tamio , Shimizu Yu‐Ichi , Takai Mitsuo , Hayashi Jisuke 
Published: March 2011

AbstractTwo‐dimensional C‐H correlation NMR spectra are presented for the native cellulose types Iα and Iβ from Cladophora sp. A remarkable difference of correlation peaks between Iα and Iβ was observed, which indicates an essential structure difference between the two types of native cellulose.
Functionality of the β(1,4) Glycosidic Linkage in Polysaccharides
Authors: Burchard Walther , Schulz Liane 
Published: March 2011

AbstractThe equatorial configuration of the β(1,4)‐glycosidic bond predestines a stretched chain conformation. These topological characteristics form the basis for laterally aggregated supramolecular structures in the solid state as well as in the concentrated solution regime. Partially substituted derivatives develop water solubility, but the dissolution process stops at a certain colloidal level. The aggregates show structural properties which are best described by a fringed micelle. These objects are built up of laterally aggregated chains forming a stem and have a peripheral shell of dangling chain sections. The striking dynamic properties indicate no segment interpenetration, and the particles lose gradually their shell mobility as the overlap concentration is exceeded.
Gel‐sol transition in gellan aqueous solutions
Authors: Miyoshi Emako , Takaya Tomohisa , Nishinari Katsuyoshi 
Published: March 2011

AbstractGel‐sol transition of sodium type gellan solutions with and without salts is studied by dynamic viscoelastic measurements and differential scanning calorimetry (DSC). Mechanical spectra show that gellan aqueous solutions behave as an entangled polymer solution in the concentration range around 2 wt.‐% at temperatures >15°C and as a weak gel below this temperature. Concentrated solutions (> 3 wt.‐%) show a true gel behavior below 30°C. The two step transition is observed for 2∼3 wt.‐% gellan aqueous solutions in thermal scanning rheological (TSR) measurements; the transition at a higher temperature is attributed to a coil‐helix transition whilst the transition at a lower temperature is attributed to sol‐gel transition. The transition observed in dilute solutions of gellan is attributed to the coil‐helix transition whilst the sol‐gel transition occurs simultaneously with coil‐helix transition in more concentrated solutions (>3 wt.‐%). The sol‐gel transition temperature shifts to higher temperatures with increasing concentration of the added salts. Junction zones formed in the presence of divalent cations are far more heat resistant than those with monovalent cations judging from both DSC and TSR, however, the possibility of the formation of junction zones by covalent bonds or by ionic bonds is excluded.
Inclusion compounds of derivatized amyloses
Authors: Kubik Stefan , Höller Olaf , Steinert Andreas , Tolksdorf Martin , Wulff Günter 
Published: March 2011

AbstractInclusion complexes of slightly hydroxypropylated amylose with organic guest molecules have been investigated by means of c.d. spectroscopy and microcalorimetry in aqueous solution. From these results, the structure of the complexes and the mechanism of their fomation are deduced. It is concluded that amylose can adjust its helix conformation to the shape and structure of the guest molecule included. Investigations about intramolecular and intermolecular crosslinking of amylose indicate that the complexing behavior of amylose can be manipulated specifically.
Coordination equilibria in transition metal based cellulose solvents
Authors: Burger Joachim , Kettenbach Gerhard , Klüfers Peter 
Published: March 2011

AbstractTaking into account the coordination chemistry of divalent palladium and nickel, two new cellulose solvents have been developed. Pd‐en is an aqueous solution of the ethylenediamine palladium complex [(en)Pd(OH)2]. Low molecular diols are deprotonated twice in Pd‐en and form a five membered chelate ring with the transition metal. Cellulose dissolves in Pd‐en to give a yellow solution, which allows light scattering analysis. NMR investigation of the solutions are simplified due to the diamagnetism of palladium(II) complexes. — The analysis of solution equilibria is essential in the development of complexing polysaccharide solvents. This feature is demonstrated by means of the new cellulose solvent Ni‐tren, which is an aqueous solution containing tris(2‐aminoethyl)amine, nickel salt and hydroxide in a molar ratio of ≥1:1:2. The difference in the cellulose solving mechanism between Ni‐tren and the long known solvents ‘nioxen’ and ‘nioxam’ developed by Jayme in the 1950ths is outlined. The question, wether or not the dissolution of cellulose in a complexing solvent is a derivatization, is discussed.
Biological control of cellulose
Authors: Tajima Kenji , Fujiwara Masashi , Takai Mitsuo 
Published: March 2011

AbstractThe enhancement of bacterial cellulose (BC) productivity using sucrose as a carbon source has been obtained by the co‐cultivation of two different types of acetic acid bacteria. BC yields for the given mix ratio of bacteria were larger than that of control. The contents of water‐soluble polymer (WSP) in the BC composites (BCCs) are a range of 5–30 wt‐%. This will be due to the formation of glucose and fructose through the hydrolysis of sucrose by sucrase secreted from Acetobacter sp. In addition, this preparation method would be applied to synthesize a new type of BC having both high biodegradability and other functions.
Synthesis of functional polymers bearing pendant mono‐and oligo‐saccharide residues
Authors: Minoda Masahiko , Yamaoka Katsushi , Yamada Kenji , Takaragi Akira , Miyamoto Takeaki 
Published: March 2011

AbstractThe present paper focuses on (i) a new synthetic methodology to prepare vinyl ether‐based synthetic glycoconjugates (glycopolymers) with well‐controlled structure, and on (ii) the application of glycopolymers bearing modified disaccharide residue as thermotropic liquid crystalline (LC) materials. Two vinyl ethers (VEs) having pendant glucose residues with their hydroxyl functions protected by acetyl and isopropylidene groups, respectively, were found to undergo living cationic polymerization initiated by a HI/ZnI2‐initiating system. Deprotection of the resultant monodisperse polymers led to water‐soluble polymers bearing a pendant glucose residue. Sequential living block copolymerization of glucose‐containing VE and alkyl VE, and subsequent deprotection afforded an amphiphilic block copolymer of well‐controlled structure. Transmission electron microscopic observation of its cast thin film revealed microphase‐separated surface morphologies that varied with varying segment composition ratio. A VE substituted with a heptadecanoated cellobiose pendant was independently prepared, and was cationically polymerized to give a thermotropic LC polymer. From X‐ray analysis, the mesophase was assigned to a discotic columnar in type, in which each main chain, extended due to the steric repulsion between the neighboring bulky pendants, was surrounded by three discotic columns.
Dynamic mechanical investigations of different substituted cellulose o‐silyl ethers
Authors: Henze‐Wethkamp Heinrich , Zugenmaier Peter , Stein Armin , Klemm Dieter 
Published: March 2011

AbstractIn contrast to many cellulose derivatives, the cellulose O‐silyl ethers with bulky side groups exhibit scarcely a change in glass transition temperature by a variation of the degree of substitution (DS) or degree of polymerization (DP) or by introducing phenyl carbamate groups for the remaining hydroxyls along the main chain. However, a substitution of these hydroxyls by flexible acetate groups lowers the glass transition temperature considerably. The secondary dispersion (relaxation) behavior is strongly influenced by the various substituents and can be correlated to specific motions of the molecules. The dynamic mechanical properties are also dependent on the kind of preconditioning of the samples.
Physical aspects of polymer stabilization
Authors: Földes Enikó 
Published: March 2011

AbstractTransport properties of additives in polymers were studied by measuring the diffusion rate and solubility of different antioxidants in ethylene polymers. Correlation was found between the diffusion rate and the fractional free‐volume of the noncrystalline phase of polymer, as well as the specific volume of diffusant. The measured solubility values were evaluated by the extended thermodynamic theory of solution of solids.
Blends of synthetic and natural polymers as special performance materials
Authors: Giusti Paolo , Lazzeri Luigi , Cascone Maria Grazia , Seggiani Maurizia 
Published: March 2011

AbstractThe interest for blends of synthetic and natural polymers is growing and several applications in many different fields are now becoming evident. The biological‐synthetic polymers interactions play a relevant role in controlling the mechanism that constitutes the basis of biocompatibility of materials used in medicine. This work concerns with the preparation and chemico‐physical and mechanical characterization of blends in which the biological component is hyaluronic acid or its benzyl ester derivatives, and the synthetic component is poly(vinyl alcohol) or ethylene‐vinyl alcohol copolymers.
Drop deformation in polymer blends during uniaxial elongational flow
Authors: Delaby I. , Froelich D. , Muller R. 
Published: March 2011

AbstractThe deformation in uniaxial elongational flow of dispersed droplets in immiscible molten polymer blends was studied for negligible interfacial tension and for viscosity ratio p = η(drop)/η(matrix) between 0.005 and 13, with an original method based on quenching elongated specimens. Although drop deformation (drop major axis over initial diameter) was in the range 1 < λd < 5, a good overall agreement was found with the small deformation Newtonian theory, which predicts that the drop versus matrix deformation ranges from 5/3 to 0 when p increases from 0 to infinity. The theoretical prediction that for p lower than 1, the droplet should deform more than the faraway surrounding matrix, with a limiting ratio of 5/3 at vanishing droplet viscosity, was experimentally verified.
New polyolefin plastomers and elastomers made with insite™ technology: Structure ‐ property relationship and benefits in flexible thermoplastic applications
Authors: Batistini Antonio 
Published: March 2011

AbstractThe polymerization of ethylene and 1‐octene by a recently developed homogeneous constrained geometry catalyst produces elastomers and plastomers with narrow molecular weight distributions, short chain branching compositions and the unique presence of long chain branching. Particular morphology and network structures in function of density give rise to excellent mechanical and physical properties which make these co‐polymers suitable for a broad range of consumer durable and packaging applications.
Multiphase polypropenes prepared by reactive blending
Authors: Mülhaupt Rolf , Stricker Florian , Barghoorn Peter , Rösch Joachim 
Published: March 2011

AbstractMultiphase polypropenes, reinforced with rigid SiO2 or polyamide 6 (PA6) microparticles, respectively, were prepared to study the influence of morphology and elastomeric interlayers on toughness/stiffness balance. Reactive processing technology was developed to in‐situ encapsulate rigid microphases in elastomeric shells. Such core/shell‐type morphologies were compared with those comprising simultaneously dispersed separate rigid and rubbery microphases. Unusual property synergisms of polypropene/polyamide 6 (70 v. %/30 v. %) blends were attributed to the formation of cocontinuous self‐assemblies of core/shell‐type PA6/SEBS microparticles.
Properties and application of luster pigments
Authors: Ostertag Werner , Mronga Norbert 
Published: March 2011

AbstractIn contrast to conventional pigments, which interact with light by absorption and/or diffuse scattering, effect or luster pigments show optical properties that are due to specular reflection of light by aligned flaky particles. Their main property is goniochromaticity, i.e. the change of lightness and/or color hue with the viewing angle of the observer. The paper describes the different type of luster pigments, their optical properties and applications and manufacturing methods.
Computer simulations of energetic and conformational changes in polymer systems
Authors: Kreitmeier Stefan , Wittkop Markus , Göritz Dietmar 
Published: March 2011

AbstractUsing a Monte Carlo method, the deformation behavior of single polymer coils was investigated. Random walks were used to verify the stretching procedure. The prediction of Pincus and DeGennes for self avoiding walks could be confirmed. The simulations at finite temperatures showed a transition from entropy to energy controlled behavior. The coils underwent a clear nonaffine deformation pattern.
Molecular recognition directed self‐assembly of tubular supramolecular architectures from building blocks containing monodendrons as exo‐receptors and crown‐ or pseudo‐crown‐ethers as endo‐receptors
Authors: Percec Virgil , Johansson Gary , Schlueter Douglas , Ronda Joan C. , Ungar Goran 
Published: March 2011

AbstractThe principles of self‐assembly of tapered exo‐receptors constructed from monodendrons containing crown‐ether, oligooxyethylenic groups and polymer backbones as endo‐receptors into tubular supramolecular architectures are described with selected examples. In the case of polymers with flexible backbones it is suggested that a helical chain conformation is induced during the assembly of its own tapered side groups. This mechanism is supported by the enhanced self‐assembling ability of tapered side groups attached to a backbone with rigid helical conformation.
Spectroscopic studies of conducting polymers
Authors: Furukawa Yukio , Sakamoto Akira , Tasumi Mitsuo 
Published: March 2011

AbstractElectronic and vibrational spectra of poly(p‐phenylenevinylene) doped with donors or acceptors have been studied, together with the spectra obtained for the radical ions and divalent ions of its oligomers. The electronic absorption spectra of doped poly(p‐phenylenevinylene) in the region from visible to near‐infrared show two bands for the H2SO4‐doped species and one very broad band for the Na‐doped species. On the basis of the analyses of resonance Raman spectra, the two electronic absorption bands of the H2SO4‐doped species are attributed to a polaron‐lattice structure, whereas the broad band of the Na‐doped species is attributed to overlapping absorptions associated with localized electronic levels of polarons and bipolarons. A Pauli spin susceptibility of the H2SO4‐doped species is explained by the polaron‐lattice structure.
Physical properties and processing conditions correlations of the ldpe/lldpe tubular blown films
Authors: Campbell Gregory A. , Babel Ashok K. 
Published: March 2011

AbstractExperiments are carried out to verify a theory developed to correlate the strain history of the polymer during film blowing to the ultimate physical properties of the film. The theory predicts that the amount of strain put into the film once it starts to freeze, defined as strain in the amorphous region and the plastic strain, has a dominant effect on the film properties. Two grades of low and linear low density polyethylene, experimental resins supplied by Mobil chemical company, were used to produce the blown film yielding a 1.25 mil film at the for all experimental runs. Film surface and bulk temperatures, along the machine direction and around the bubble, were measured using the infra‐red techniques to identify the points where film starts to crystallize. A video digitization technique was used to measure the bubble kinematics. Film properties were measured using standard ASTM methods. The results indicate a correlation between the amount of strain and a measure of stress with ultimate physical properties of the blown film. This principle leads to the correlation of both the machine and transverse film properties on the same surface. The results obtained can potentially be exploited by designing the blown‐film equipment and processing conditions such that optimal bubble stretching produces desired film properties.
Macromolecularization of fullerenes and the charge transfer complex formation of fullerenes with polymers having electron‐donating or electron‐accepting moieties
Authors: Li Fu‐Mian 
Published: March 2011

AbstractC60 was bonded to allylamine homopolymer (PALA) and its copolymers with styrene, 2‐hydroxypropyl methacrylate etc. as a pendant functional group. The polyallylamine bonded C60 displays fluorescence at room temperature although C60 does not in itself. This may be due to the lessening of highly symmetrical shape of C60. Some C60‐amine adducts are prepared as the model of polyallylamine‐C60 for the clarification. C60 doped poly(tetrahydrofurfuryl methacrylate) film has been prepared and its optical non‐linearity has been investigated. The charge transfer complexes formation of C60 with polymers having electron‐donating chromophore moieties such as poly(dimethylaminostyrene), poly(acryloylphenothiazine), poly(acryloylphenoxazine) and poly(styrene‐co‐dimethylaminophenylmaleimide) as well as with polymer having electron‐accepting chromophore moiety poly(cyanophenylacrylamide) have been manifested.
Synthesis and application of inorganic/organic composite materials
Authors: Schmidt Helmut K. 
Published: March 2011

AbstractA new type of inorganic‐organic composite has been developed using organic monomeric or polymerizable silanes (with appropriate organic groupings like double bonds or epoxides) as monomers or in situ prepared or separately added nano‐scale ceramic or metal particles. Due to the small size of the particulate phase, these composites are still highly transparent but show properties at least partially to be attributed to the inorganic phase. The introduction of special functions into these materials has been used for the fabrication of interesting functions like non‐linear optical properties, low surface free energy coatings, controlled release properties or special mechanical properties (scratch resistance).
Biochemical and biomedical application of monodisperse polymer particles
Authors: Ugelstad John , Stenstad Per , Kilaas Lars , Prestvik Wenche S. , Rian Anne , Nustad Kjell , Herje Ragnhild , Berge Arvid 
Published: March 2011

AbstractMacroporous particles with large pores are used for size exclusion chromatography of carbohydrates with very high molecular weights. Macroporous particles of different sizes are used for multiple immunofluorometric analysis by flow cytometry. Porous magnetic particles with protein A coupled to the surface of the pores combine a high capacity in binding of IgG with easy handling of the particles. Magnetic beads with boronic acid coupled to the surface are applied for selective isolation of subclasses of cells. The beads are detached from the cells by addition of sorbitol, leaving free, pure cell fractions in good yield. The use of magnetic particles in molecular biology is described.
Organic electroluminescent and nonlinear optical materials
Authors: Saito Shogo , Tsutsui Tetsuo , Era Masanao 
Published: March 2011

AbstractThe multilayer electroluminescent(EL) devices composed of vacuum‐sublimed organic films are discussed with the aims of achieving high luminance and proposing an optical micro‐cavity. For the former purpose, requirements for confinements of carriers and excitons within the thin emissive layer are shown by taking accounts of ionization potentials, electron affinities and excitation energies in organic thin films. Concerning the interference effect of emitted light, we show the variation in the intensity of emission and a strongly directional light from the micro‐cavity. Second‐order nonlinear optical(NLO) films are designed by preparing noncentrosymmetric LB multilayers composed of an pyrazine derivative with large hyperpolarizability and arachidic acid. Third‐order nonlinear optical(NLO) films are proposed by using polyarylenevinylene films. In order to fabricate excellent third‐order nonlinear optical(NLO) films, highly oriented polyarylenevinylene films are prepared by using a LB technique.