bluuebunny/crossref_metadata_2025_split huggingface dataset:
SAXS and WAXS investigations of mass coloured polyamide fibres
Authors: Wlochowicz A. , Broda J. 
Published: April 2003

AbstractThe supermolecular structure of uncoloured and mass coloured polyamide‐6 fibres has been investigated by means of SAXS and WAXS methods. Three different kinds of organic pigments have been used for the study. During fibre formation a crystalline lamellar structure is formed. The crystalline phase contains the α and γ modification. The pigment Copper Phthalocyanine Blue causes an increase of the content of the α‐form. During drawing of the fibres a recrystallization process occurs leading to changes of the structural parameters. These changes are independent of the presence of pigments.
Investigations on the cold crystallization of pure and filled PETP by dielectric measurements
Authors: Nowak H. , Kalinka G. , Hinrichsen G. 
Published: April 2003

AbstractThe cold crystallization of pure and filled poly(ethylene terephthalate) (PETP) after quenching from the melt has been investigated by dielectric measurements in two different modes: The first one using constant heating‐rate (in the temperature range from 320 to 480 K) and the second one under isothermal conditions (at 378 K). The complex dielectric constant (ϵ′, tan δ) is influenced by crystallization. Two α‐relaxation regions are identified: The αa‐relaxation region from the pure amorphous phase and the α′‐relaxation region from the spherulitic phase. The investigations on the filled systems (PETP + 10% aramid puple, PETP + 30% short glass fibres) prove that an influence of the fillers on the time delay and rate of crystallization and on the geometry of the growing spherulites exists.
Ring‐opening polymerization of 2‐phenyl‐1,3,2‐dioxaphosphorinane initiated with new catalyst system using a halobenzene and nickel(II) bromide
Authors: Kobayashi S. , Kadokawa J. 
Published: April 2003

AbstractRing‐opening polymerization of 2‐phenyl‐1,3,2‐dioxaphosphorinane (a six‐membered cyclic phosphonite, 4) has been initiated with a new catalyst system of a halobenzene and NiBr2. The polymerization proceeded in a living nature to produce poly(phosphinate) consisting exclusively of a “normal” unit. The kinetic analysis of the polymerization of 4 initiated with the catalyst system was successfully carried out. The rate constant of propagation (kp) was much lower than that initiated with MeI. Linear and star‐shaped telechelic polymers were synthesized using di‐, tri‐, tetra‐, and hexa‐ halobenzenes as a catalyst component.
XPS investigations on adsorption of polyurethanes and chlorinated poly(vinylchloride) on chromium dioxide
Authors: Gähde J. , Loeschcke I. , Fischer Th. 
Published: April 2003

AbstractThe adsorption behaviour of a polyurethane‐elastomer (PUR) and a chlorinated poly(vinylchloride) (CPVC) on unstabilized magnetic chromium dioxide is described. The polymers were adsorbed on chromium dioxide from a solution of tetrahydrofuran individually or as a mixture. The polyurethane is preferably adsorbed, and it is able for displacing CPVC in the adsorption layer. An enriching of CPVC in the phase boundary layer to chromium dioxide by process engineering parameters is not succeeded. Partial cross‐linking of the adsorption layer was registered during storage under the effect of temperature and humidity.
High temperature superconducting ceramics from polymer metal precursors
Authors: Lampe I.v. , Lorkowski H.‐J. , Wäsche M. 
Published: April 2003

AbstractWe report on the preparation of polymer metal precursors, their thermoanalytical degradation and their transformation to high temperature superconducting (HTS) Y‐Ba‐Cu‐O or Bi‐Sr‐Ca‐Cu‐O compounds. The thin precursor film was patterned by electron beam lithography and subsequently transformed to HTS phases.
Ziegler‐Natta polymerization of ethylene with Ti‐Mg catalysts anchored on polymeric supports
Authors: Fuhrmann H. , Pohl M.‐M. 
Published: April 2003

AbstractThe immobilization of Ti‐Mg catalysts via polymeric Grignards on crosslinked polystyrenes has been achieved in the presence of methylene spacers of varying length. The resulting catalysts are tested in the homopolymerization of ethylene in a suspension process at 85°C and a total pressure of 6 bar. Hydrogen has been used as molecular weight controlling agent. The polymerization activity of the catalysts is significantly enhanced when a MgCl2 phase is generated in the course of catalyst preparation. The results are supported by SEM and TEM techniques.
Synthesis and investigation of α,ω‐methacryloyl poly (epoxide‐carboxylic acid) and α,ω‐methacryloyl poly (epoxide‐phenol) macromonomers
Authors: Klee J. E. , Claußen F. , Hörhold H.‐H. 
Published: April 2003

Abstractα,ω‐methacryloyl terminated macromonomers containing epoxide‐carboxylic acid and epoxide‐phenolic repetitive units were synthesised. They were prepared in the molecular range from 600 to 2000 g/mol by a two‐step reaction. At first prepolymers were formed from bisphenol‐A diglycidyl ether and carboxylic acids or phenols and then reacted in a second step with methacrylic acid to the macromonomers. Their structure is proved by elemental analysis, Mn (vpo) values, IR and NMR spectroscopy. By using HPLC and GPC analysis it was shown that the macromonomers consist of oligomer homologous series. The distribution of the oligomers agrees with the calculated ones. Furthermore HPLC analysis and NMR spectra show that the epoxide rings were opened by SN1‐ and SN2‐type reactions.
New developments in synthesis of star polymers with poly(ethylene oxide) arms
Authors: Rein D. , Lamps J. P. , Rempp P. , Lutz P. , Papanagopoulos D. , Tsitsilianis C. 
Published: April 2003

AbstractThe synthesis of star molecules consisting of small polydivinylbenzene (DVB) cores carrying a number of hydrophilic poly(ethylene oxide) branches has been investigated. Two different methods are discussed:
The “core‐first” technique, in which living poly(DVB) cores are used to initiate the polymerization of oxirane. This method is flexible and efficient, but the samples obtained exhibit broad molecular weight distributions, arising from large fluctuations of the core functionalities (and core sizes). The same method has been applied successfully to the synthesis of star‐block copolymers, in which each branch consists of a polystyrene (PS) block and a poly(ethylene oxide) (PEO) block.
The “three‐step” method (“In‐Out”) involves the use of living polystyrene “seed‐star” molecules as initiators for the polymerization of oxirane. The “seed‐stars” themselves arise from a classical “arm‐first” process. This method allows a better control of the functionality of the cores. The number of branches of either kind attached to a given core is equal. Hetero‐star PS‐PEO copolymers are obtained, but the length of the branches of either kind can be chosen at will within broad limits.
The interaction of acrylic diblock‐copolymers with aluminum oxide surfaces and their application for ceramic powder processing
Authors: Rudolph J. , Patzsch J. , Meyer W. H. , Wegner G. 
Published: April 2003

AbstractAmphiphilic diblock copolymers were prepared by anionic copolymerization of t.‐butylmethacrylate (TBMA) with methylmethacrylate (MMA) and n‐butylmethacrylate (NBMA) respectively, followed by polymer analogous conversion of the TBMA‐into methacrylic acid‐ (MAA) blocks. These materials are highly efficient dispersants for oxide and nitride ceramic powders. A series of samples with Mn ranging from 4.000 to 135.000, and with block length ratios from 0.5 to 14 (MMA/MAA) with polydispersities close to 1.0 were obtained.The influence of total molecular weight and block length distribution of the copolymers and quality of the solvent system on their interaction with α‐Al2O3 were studied by sedimentation, adsorption experiments and surface plasmon resonance (SPR). The acrylic diblock copolymers are adsorbed irreversibly at the alumina surface. The conformation of the adsorbed macromolecules depends on the “quality” of the solvent. With respect to powder dispersing efficiency, an optimum is found when the polymers consist of short anchoring and stabilizing blocks.
Carbohydrate modified polysiloxanes II. Synthesis via hydrosilation of mono‐, di‐and oligosaccharide allylglycosides
Authors: Jonas G. , Stadler R. 
Published: April 2003

AbstractThe synthesis of linear carbohydrate modified polysiloxanes has been successfully performed by hydrosilation of functionalized and protected carbohydrate derivates. The functionalization (allyl glycosilation) may be applied to a wide variety of reducing carbohydrates. In this study, mono‐, di‐ and oligosaccharides were converted by a simple two‐step reaction (β‐acetylation and allyl glycosilation) into active compounds, allowing the polymer analogous addition to random poly[dimethyl‐co‐hydromethyl]siloxanes (hydrosilation). By variation of the Si–H amount in the starting polymers, polysiloxanes with 1.5% to 56% (by weight) carbohydrate content were prepared.At small degrees of substitution the modified polysiloxanes remain soluble in non‐polar media. With increasing carbohydrate content the polymers become more and more soluble in polar solvents like isopropanol or methanol. A polysiloxane with 29% maltose modified comonomeric units (56 wt.‐% carbohydrate content) was fully water soluble.
Synthesis and examination of chiral liquid crystalline side chain polymers
Authors: Kossmehl G. , Nagel H.‐I. , Haase W. , Meyer J. 
Published: April 2003

AbstractSubstituted poly(methylsiloxane)s connected by a spacer with a biphenyl system that is esterificated with a chiral α‐chlorocarboxylic acid have been synthesized and characterized. Their liquid crystalline properties have been studied by differential scanning calorimetry (DSC), polarization microscopy, electro‐optical methods and X‐ray diffraction. Most of the synthesized compounds and polymers have liquid crystalline phases, mainly smectic phases.
Effects of pH, ionic strength, and type of anion on the rheological properties of chitosan solutions
Authors: Chen R. H. , Lin W. C. , Lin J. H. 
Published: April 2003

AbstractChanges in the rheological properties of chitosan solutions with pH, ionic strength, and type of anion were studied. Between pH 2.0 and 5.0, apparent viscosities increased with the decrease of pH in chitosan–organic acid solutions, while in chitosan–HCl solutions they behaved oppositely. In chitosan–NaOH solutions, they decreased with the increase of pH between pH 5.0 and 6.0, then increased as pH further increased to pH 6.0–6.4. The difference may be due to different interactions of counterions with macroions and also the third electroviscous effect. Relative viscosity increased with a decrease in chitosan concentrations at concentrations below 1.5 × 10−3 M. Intrinsic viscosities changed with media pH and ionic strength.
Telechelic prepolymers and macromonomers by step growth processes
Authors: Klee J.E. 
Published: April 2003

AbstractThe article describes recent achievements in the field of telechelic epoxide‐amine and epoxide‐dithiol prepolymers and of macromonomers which can be obtained by step growth processes of epoxides with amines, carboxylic acids or phenols. The distribution of the oligomers is investigated with the help of HPLC and GPC. Furthermore the reaction of epoxideamine prepolymers with cyclic carboxylic acid anhydrides is described as well as their polymerization to new hybrid networks. The prepolymers with their β‐hydroxypropyl structural units are able to form complexes with metal ions. We have used this property for the extraction of Cu2+ ions from water solutions.
Rheological study of polymer‐surfactant interactions in cellulose derivatives and gelatin aqueous solution
Authors: Pisárčik M. , Bakoš D. 
Published: April 2003

AbstractThe rheological properties of water soluble cellulose derivatives (hydroxypropylcellulose, modified hydroxyethylcellulose) and gelatin aqueous solutions in a system with ionic surfactant were studied. The viscosity maximum was found in the region of critical micellar concentration (CMC) of the surfactant as a result of micelle formation. An increase of the CMC value with increasing molecular weight was observed and a decrease of this value for the hydrophobically modified polymer solution was found compared to the CMC value of the surfactant aqueous solution. A slight viscosity maximum was also found in gelatin systems with cationic and anionic surfactant. The viscosity increase (cross bonding) of gelatin aqueous solutions is more affected by a cationic surfactant than by an anionic one. pH measurements on gelatin systems indicate that the minimal viscosity is reached in the region of the isoelectric point.
Some experimental and theoretical data on the dielectric relaxation in dilute polystyrene suspensions
Authors: Carrique F. , Zurita L. , Delgado A.V. 
Published: April 2003

AbstractThe study of the conductivity and dielectric response of colloidal suspensions when subjected to an alternating electric field can give a great deal of information on the characteristics of the solid‐liquid interface, as well as on the dynamic processes taking place in such systems. In fact, measurements of the dielectric relaxation spectra on colloids are more sensitive to the nature of the surfaces than any other electrokinetic technique. This work deals with this problem in dilute polystyrene suspensions. Their complex conductivity and dielectric constant are experimentally measured as a function of both the frequency of the applied field and the latex volume fraction, in KCl solutions. From these data, certain quantities have been obtained that can be compared to the predictions of advanced theoretical models. The agreement between theoretical and experimental data is qualitatively excellent, although the latter are significantly larger that the former. Reasons for such discrepancies are discussed in the light of recent experimental results and double layer models.
Mn(II) coordination and ionic conductivity in ionene glasses
Authors: Rietz R.‐R. , Hölz G. , Meyer W.H. , Spiess H.W. , Wegner G. 
Published: April 2003

AbstractGlasses from cationic polyelectrolytes of the type “ionenes” are considered as being a new class of materials. Below their glass transition the quaternized ammonium groups in the polymer backbone are essentially static, due to their strong Coulomb interactions. At the glass transition temperature (Tg) the N+ cations become mobile. However, both the low molecular weight counterions and the organic chain segments linking the cations are already mobile below Tg. Therefore, in contrast to other polymers, the glass transition in ionenes is characterized by the relaxation of the cationic centers. Ionic conductivity in the glassy state is based on thermally activated anion transport. In this paper, the influence of the coordination of Mn2+ in the [MnBr4]2− ‐anions on the solid state properties is investigated by electron paramagnetic resonance (EPR) and by dielectric spectroscopy. The local structure of the magnetically active Mn2+ centers in the ionene glass is found to have a tetragonally distorted symmetry at low temperatures, which is transferred into Td symmetry of [MnBr4]2− via a distorted octahedral transition state [MnBr42−‐Br22−] gives rise to an additional dielectric relaxation and to an unusually high activation energy for the anion transport.
Prediction of deformative and thermal properties of hybrid fiber composites with polymer matrix
Authors: Kochetkov V. A. , Maximov R. D. 
Published: April 2003

AbstractA theoretical and experimental investigation was carried out to examine the possibilities of a structural approach for prediction of elastic constants, creep functions and thermal characteristics of hybrid polymer composites reinforced with anisotropic fibers of several types. The theoretical solutions were obtained by generalizing the self‐consistent method for the case of a three‐phase model. The effects of brittle fiber breakdown under tension in the direction of reinforcement of a unidirectional hybrid composite were studied under conditions of short‐term loading and long‐term creep. A variant of the solution is proposed for predicting the thermal deformation of a hybrid composite containing not only elastic, but also viscoelastic thermorheologically simple components with different temperature–time shift factors. The experimental confirmation of the predicted results was done on specimens of organic/glass, organic/carbon, glass/carbon and organic/boron polymer composites with different ratios of volume contents of fibers.
Wetting behavior in three‐component polymer blends
Authors: Desai R. C. , Yeung C. , Noolandi J. 
Published: April 2003

AbstractWe determine the interfacial properties of a three‐component polymer blend in three‐phase coexistence. We discuss how the presence of the third component affects the behavior of the interface between two phases. We demonstrate the existence of a wetting transition in which one of the minority phases wets the other. Our results indicate that both first‐ and second‐order wetting transitions occur.
Characterization of linear low density polyethylene by temperature rising elution fractionation and by differential scanning calorimetry
Authors: Mara J. J. , Menard K. P. 
Published: April 2003

AbstractIn this study, solution crystallized samples of LLDPE were characterized by differential scanning calorimetry (DSC) to ascertain the feasibility of utilizing the DSC technique as an alternative to analytical temperature rising elution fractionation (TREF). All steps, from dissolving the polymers to crystallizing by controlled cooling to analysis were performed in the DSC. The DSC results were compared with analytical TREF runs using two commercial LLDPEs (designated Resins A and B). Both techniques provided similar compositional distribution information with the calorimetric results being obtained in considerably less time. In particular, resins evaluated via both techniques showed distinct bimodal distributions, although the shapes of the curves were not identical. For example, as measured calorimetrically, Resins A and B contained approximately 69% and 59%, respectively, of the lower melting, more branched species. These results compared favorably with analytical TREF runs which indicated that Resins A and B contained about 68% and 58%, respectively, of the lower melting, more branched species.
Preparation of light emitting diodes on flexible substrates: Elimination reaction of poly(p‐phenylene vinylene) at moderate temperatures
Authors: Herold M. , Gmeiner J. , Schwoerer M. 
Published: April 2003

AbstractWe report on detailed measurements of the elimination reaction of poly(p‐phenylene vinylene) (PPV) prepared by the precursor route. The influence of the temperature on the conversion was investigated by optical absorption measurements. Compared to the elimination reaction in vacuum we find that the temperature necessary for the elimination reaction is remarkably reduced if carried out in a proper exchange gas. As a result, we have prepared the first flexible light emitting diodes (LEDs) of PPV on polymer foil substrates.
Statistical mechanical theory for liquid‐crystalline polymer solutions
Authors: Sato T. , Teramoto A. 
Published: April 2003

AbstractA statistical mechanical theory is presented for liquid‐crystalline polymer solutions, where the liquid‐crystalline polymer is regarded as a wormlike spherocylinder interacting by the hard‐core repulsion and a soft (attractive or electrostatic) interaction with other spherocylinders. The theory is based on the following two assumptions: (1) the intramolecular excluded volume effect is not effective and (2) the interaction between pair of spherocylinders can be treated by the “single contact approximation”. These assumptions are relevant to a polymer with a stiff backbone and not very long contour length. The theory is used to predict thermodynamic and spatial properties of isotropic solutions and also isotropic‐liquid crystal phase equilibrium behavior. The predicted solution properties and phase behavior are favorably compared with experimental results for some selected stiff‐chain liquid‐crystalline polymers.
On the copolymer and cross‐linking contribution to the glass transition temperature of model networks
Authors: Reekmans B. J. , Shi Ji‐Feng , Pyati M. , MacKnight W. J. , Lillya C. P. 
Published: April 2003

AbstractThe effect of molecular structure on the glass transition temperature of end‐linked networks has been studied by examining a series of stoichiometrically imbalanced poly(propylene glycol)‐Desmodur RF (PPG‐DRF) and poly(isoprene)tristar‐hexamethylene diisocyanate (PIP‐HDI) networks. A range of different molecular weights of each prepolymer was used. The PPG‐DRF system shows a strong influence of the copolymer contribution on Tg. The modified copolymer approach (MCA) gives good theoretical correspondence with the experiments. This approach successfully predicts the Tg behavior of other cross‐linked systems with relatively high cross‐link densities. Other existing universal theories have been shown not to describe the Tg well for the PPG‐DRF system. Correction of the MCA is possible to account for a small plasticizing effect observed for highly stoichiometrically imbalanced samples. The PIB‐HDI system shows no strong contribution of the copolymer effect by virtue of its structure. The difference in cross‐link density can explain the changes in Tg. The MCA also yields reasonable results. For both systems it is necessary to consider all cross‐linkers for the purpose of determining the cross‐link density.
Polysilylenes with ethynylphenyl substituents
Authors: Frey H. , Schulenburg E.‐J. , Möller M. , Noorlander‐Bunt H. , Engbersen J. F. J. , Reinhoudt D. N. 
Published: April 2003

AbstractEthynylphenyl‐methyldichlorosilane (EPDMS) has been prepared as a new monomer for the synthesis of polysilylenes with triple bonds attached to the catenated Si chain. A series of copolymers with methylphenyldichlorosilane (MPDS) as well as the homopolymer, PEPMS, have been synthesized. The content of ethynylphenyl substituents was quantitatively analyzed by FTIR spectroscopy. The optical properties of the new polymers were studied with respect to potential π−σ interaction. No significant bathochromic shift of the UV‐absorption maximum could be detected. Unexpectedly, increasing content of incorporated EPMS units led to a decrease of the (σ−σ*) absorption. The ethynylphenyl‐substituted polysilylenes exhibited strong, temperature‐dependent fluorescence in solution as well as in films.
Anhydride‐cured epoxy resins toughened with diol‐ and bis(4‐hydroxybenzoate)‐terminated poly(tetrahydrofuran) liquid rubbers. Part I. Morphology and blend properties
Authors: Albert P. , Läuger J. , Kressler J. , Mülhaupt R. 
Published: April 2003

AbstractA novel class of liquid rubber comprises bis(4‐hydroxybenzoate)‐terminated poly(tetrahydrofuran), which reacts with bisphenol A diglycidyl ether to form segmented liquid rubbers with poly(tetrahydrofuran) and poly(hydroxyether) segments. In anhydride‐cured epoxy resins such segmented liquid rubbers afford improved toughness. Diol‐ and bis(hydroxybenzoate)‐terminated poly(tetrahydrofuran)‐based liquid rubbers are compared. It is possible to control the polymer morphology by the variation of the molecular architecture of segmented poly(tetrahydrofuran)‐based liquid rubbers. The average size of the dispersed rubber phases depends on the molecular weight of the segmented liquid rubbers and correlates with impact strength and stiffness.