bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the thermal oxidative stabilization of PAN filaments in carbon fibre processing
Authors: Walenta E. , Fink H.‐P. 
Published: April 2003

AbstractThe thermal oxidative stabilization of PAN fibres was investigated by small and wide angle X‐ray scattering and by measurements of the fibre density. It has been proved that stabilization starts in the less ordered regions and proceeds to higher ordered domains. Dimensions of these regions were estimated.
Hybridnetzwerke – Wege zur Synthese und Nachvernetzung von methacrylatterminierten Epoxid‐Amin‐Prepolymeren. Unvernetzte Epoxid‐Amin‐Additionspolymere 30
Authors: Klee J. , Hörhold H.‐H. , Schütz H. 
Published: April 2003

AbstractDie Reaktion von aminoterminierten Epoxid‐Amin‐Prepolymeren mit (2,3‐Epoxypropyl)methacrylat führt zu Prepolymeren mit Methacrylatendgruppen, deren Struktur durch Mn(VPO)‐Werte, Elementaranalyse, IR‐,1H‐NMR‐ und 13C‐NMR‐Spektroskopie gesichert ist. Durch Bestrahlung mit UV‐Licht erfolgt die Bildung von Hybridnetzwerken, die mittels Tg‐Bestimmung und IR‐Spektroskopie charakterisiert werden. Ferner wurde die Volumenkontraktion während der Polymerisation ermittelt.
Orientation ability of thermotropic liquid crystalline comb‐like siloxane polymers as studied by NMR spectroscopy
Authors: Roth H. , Krücke B. 
Published: April 2003

AbstractNematically and smectically ordered samples of comb‐like siloxane polymers were studied by FT‐1H‐NMR method to get information about the macroscopic order parameter varying the chain‐end length of the mesogenic side group. The proton spectra (line shape, splitting) reflect directly the role of the spacer in the ordering process of the comb‐like polymers.
Monomers in polymer dispersions. Part II. Sorption rates of monomers in polymer dispersions
Authors: Hörnig K. , Hergeth W.‐D. , Häusler K.‐G. , Wartewig S. 
Published: April 2003

AbstractThe sorption rate of monomers from the aqueous phase into polymer particles is determined by ultrasonic velocity measurements as well as by isothermal evaporation analysis. This sorption rate is higher than the sorption rate of monomer during the steady state of emulsion polymerization. Hence, the reaction proceeds under equilibrium conditions with respect to the monomer distribution between polymer particles and monomer reservoirs.
Untersuchungen zur gleichzeitigen Homo‐ und Heterosymplexbildung mit synthetischen Polyampholyten vom Pendant‐Typ
Authors: Kötz J. , Philipp B. , Kudaibergenov S. , Bekturov E. A. 
Published: April 2003

AbstractDie Polyanion‐Polykation‐Wechselwirkung (Symplexbildung) Wurde bei zwei ampholytischen Copolymeren aus Vinylethinylpiperidol und Acryläure bzw. des N‐methylierten Analogen und Methacrylsäure turbidimetrisch, konduktometrisch und potentiometrisch untersucht. Die Ergebnisse werden unter dem Aspekt einer konkurrierenden Homosymplexbildung zwischen den funktionellen Gruppen des Polyampholyten und Heterosymplexbildung zwischen einer Art der funktionellen Gruppen des Polyampholyten und einem entgegengesetzt geladenen Polyion diskutiert und mit früheren Resultaten bei anderen ampholytischen Copolymeren verglichen.
Investigation of the structure of poly(dodecalactam) obtained by anionic bulk polymerization
Authors: Mateva R. , Krastev V. , Ivanova M. , Nedkov E. 
Published: April 2003

AbstractThe morphology and structure of poly(dodecalactam) obtained by anionic bulk polymerization in the presence of different activators have been investigated. The structure of the polymer samples was characterized by means of infrared spectroscopy, wide angle X‐ray scattering, calorimetry, and polarizing light microscopy. It was established that at cooling of the polymer melts two crystalline modifications are formed. The effect of the polymerization conditions and of the molecular weight on the formation of the α‐ and γ‐modifications is discussed.
Untersuchungen zum thermischen Verhalten von phenolharzgebundenen Cellulosepapier‐Schichtpreßstoffen. 1. Thermoanalytische Untersuchungen an den Schichtpreßstoffen und an ihren Komponenten
Authors: Goetzky P. , Gnauck Regine 
Published: April 2003

AbstractDer thermische Abbau von phenolharzgebundenen Cellulosepapier‐Schichtpreßstoffen wird mit den Methoden der dynamischen Thermoanalyse untersucht und in Beziehung zum thermischen Verhalten der Komponenten und zur Flexibilisierung des Harzes mit Holzöl und Tricresylphosphat gesetzt.
Relaxation properties of an epoxy polymer plastified with maleic anhydride
Authors: Shut N. I. , Bartenev G. M. , Lazorenko M. V. , Sichkar T. G. 
Published: April 2003

AbstractThe relaxation properties of the epoxy dian polymer ED‐16 plastified with maleic anhydride were studied in the wide range of temperature from −150°C to + 500°C. The experimentally found great number of relaxation transitions are connected with the complex structure of the polymer and with the existence of a large number of different forms of molecular motion. The observed relaxations are classified and their characteristic constants (activation energy and preexponential factor) are given. A nonsegmental mechanism of the process of glass transition in highly crosslinked polymers is suggested.
Untersuchungen zur Polymerisation von Vinylchlorid in Mikrosuspension. Teil 1
Authors: Schirge H. , Schlegel R. 
Published: April 2003

AbstractBei der technischen Durchführung der Mikrosuspensionspolymerisation des Vinylchlorids wird eine konstante Bruttopolymerisationsgeschwindigkeit während des ganzen Reaktionsverlaufes angestrebt. Dies wird durch Verwendung eines Redoxsystems aus Dilauroylperoxid/Dicetylperoxidicarbonat, Cupfersulfat und Ascorbinsäure als Initiator erreicht.
Microporous membrane filters on the basis of poly(tetrafluoroethylene)
Authors: Kostov G. , Christova N. , Charadjiev P. 
Published: April 2003

AbstractMicroporous membrane filters were processed on the basis of different types of poly(tetrafluoroethylene) characterized by various enthalpies of crystallization and molecular mass, respectively. CaCO3, NaCl, and NH4Cl were used as appropriate reactants in order to form porous structure. The influence of the polymer as well as the type and concentration of the reactants on the properties of the membrane filters is studied.
Kinetical study of the condensation reaction of 2‐furaldehyde and 2‐furfurylidene methyl ketone. Solvent influence
Authors: De Los Rios M. Diaz , Planes R. L. , Cruz B. H. , Luna N. L. 
Published: April 2003

AbstractThe influence of solvent nature upon the formation rate of 2‐difurfurylidene ketone with the use of water, methanol, ethanol, and propanol as catalyst solvent was studied. It was verified that the reaction proceeds slowly in aqueous medium due to the low solubility of the reactants and intermediates.
Elektronenmikroskopische Untersuchungen von Polyethylenen. VII. Strukturen von UHMWPE nach Dehnung und verschiedenen thermischen Vorbehandlungen
Authors: Michler G. H. , Morawietz K. 
Published: April 2003

AbstractAn Polyethylen mit ultrahoher Molekülmasse (M̄w = 1,6 · 106) wurden elektronenmikroskopische Untersuchungen nach mechanischer Belastung und verschiedenen thermischen Vorbehandlungen durchgeführt. Die Dehnung erfolgte bei Raumtemperatur an ungetempertem und getempertem Material sowie bei höheren Temperaturen. Die zwischen den einzelnen Temperaturbehandlungen bestehenden Unterschiede im Dehnverhalten werden auf der Grundlage der Veränderungen der Strukturen der Lamellen und der zwischenlamellaren, amorphen Gebiete diskutiert. Der Einfluß der amorphen Phase auf Änderungen der Lamellengröße und räumlichen Anordnung während des Dehnprozesses wird ausführlich untersucht. Aus der quantitativen Auswertung der Lamellenlänge. Lamellendicke und Blöckchengröße werden Rückschlüsse auf die mikromechanischen Prozesse während des Dehnvorgangs, wie Lamellenrotation oder interlamellares Gleiten, gezogen.
Untersuchungen an photopolymerisierten Dimethacrylaten
Authors: Mallon H.‐J. , Utschick H. , Unseld W. 
Published: April 2003

AbstractDie photoinitiierte Polymerisation von Dimethacrylaten mit den Initiatorsystemen Campherchinon/Dimethyl‐p‐toluidin sowie Phenanthrenchinon/Dibenzoylperoxid führt zu Produkten, die noch relativ hohe Anteile nicht umgesetzter Doppelbindungen und Restmonomere enthalten. Der Restmonomergehalt beeinflußt die Eigenschaften der Polymere. Dieser Effekt und die möglichen thermischen Nachreaktionen werden mittels DSC und thermomechanischen Messungen nachgewiesen.
Ultrasonic mechanochemical degradation of the ternary copolymer poly(acrylonitrile‐co‐vinyl acetate‐co‐α‐methylstyrene)
Authors: Oprea C. Vasiliu , Popa M. 
Published: April 2003

AbstractThe ultrasonic mechanochemical degradation of poly(acrylonitrile‐co‐vinyl acetate‐co‐α‐methylstyrene) in solution is studied. Based on an experimental design whose results were processed on a computer, the function correlating the intensity of mechanodegradation with the reaction parameters concentration, temperature, and duration was obtained. The radicalic mechanism of the mechanochemical degradation was proved.
Synthesis and characterization of epoxy resin derived from cyanuric acid
Authors: Jain R. K. , Chandra S. 
Published: April 2003

AbstractA procedure is described to synthesize heterocyclic cyanuric acid based triglycidyl isocyanurate resin in good yield and purity. The purity and configuration of the resin were confirmed by determination of the melting point, IR and NMR spectroscopy, elemental analysis, and epoxide equivalent.
Polymerization of acrylonitrile initiated with citric acid‐ceric ion redox system
Authors: Göçmen A. , Başcaran B. 
Published: April 2003

AbstractThe polymerization of acrylonitrile was studied in aqueous sulfuric acid medium with the redox initiator system citric acid‐ceric ion. The effect of ceric ion, citric acid and sulfuric acid concentrations and of temperature on the monomer conversion and average molecular weights of the polymer was investigated. A polymerization mechanism is suggested.
Study of electro‐optic properties of polymer dispersed liquid crystal films with low concentration of liquid crystal
Authors: Mucha M. , Kryszewski M. 
Published: April 2003

AbstractPolymer dispersed liquid crystal films were prepared from radiation cured polyester resin containing low concentration of the nematic liquid crystal hexyloxycyanobiphenyl. The electro‐optic properties of the liquid crystal domains in the polymer matrix are dependent on the time elapsed between the occurrence of phase separation of the liquid crystal from the homogeneous mixture with the polymer precursor and the onset of polymer hardening.
Preparation and characterization of novel poly(phenylquinoxaline‐imide‐amide)s
Authors: Bruma M. , Hamciuc E. , Sava I. , Hamciuc C. , Belomoina N. M. , Krongauz E. S. 
Published: April 2003

AbstractPoly(phenylquinoxaline‐imide‐amide)s have been prepared by low‐temperature solution polycondensation of aromatic diamines containing preformed phenylquinoxaline units and amide or imide groups with diacid chlorides of certain dicarboxylic acids incorporating imide rings. These polymers are easily soluble in polar aprotic solvents and give transparent films with high thermal stability and good electrical insulation properties.
Thermally stimulated depolarization currents in poly(vinyl alcohol) films
Authors: Rao V. V. R. Narasimha , Krishna K. Jeevana , Rao B. Subba 
Published: April 2003

AbstractPoly(vinyl alcohol) films were polarized at different electrical field strengths and temperatures. The peak temperature of the TSDC spectra shifted to higher values with increasing polarizing field strength and polarizing temperature. The activation energies and relaxation parameters of the process were evaluated. Based on the results, the origin of TSDC was attributed to space charge polarization with some contribution of dipole orientation.
Infrared spectroscopic study of the functional composition of alkylaromatic nitrooligomer derivatives
Authors: Karaivanova M. , Kostov V. , Stoeva V. 
Published: April 2003

AbstractBy reaction of butadiene styrene rubber with a nitrating mixture alkylaromatic nitrooligomer derivatives are formed. The reaction was carried out in dichloroethane solution for 2 to 5 h at temperature 20 to 50°C. The functional composition of the nitrooligomers in dependence on temperature, reaction time, and composition of the nitrating mixture was determined by means of infrared spectroscopy. It was established that at high concentrations of NO2+ the nitration of the aromatic ring is predominant, while at low concentrations the nitration of the hydrocarbon chain prevails.
The dynamic behaviour of longitudinal and transverse components of the emitting oscillator and the internuclear vector manifested in polarized luminescence and in the nuclear overhauser effect
Authors: Gotlib Yu. Ya. , Torchinski I. A. , Shevelev V. A. 
Published: April 2003

AbstractIn the frame work of the tetrahedral lattice model with a three‐unit kinetic element, the time correlation functions were found. These functions describe the dynamics of “longitudinal” and “transverse” components of the emitting oscillator vector of the luminescent marker included in the side group or the dynamics of the internuclear vector of 13C‐1H. The expressions were obtained for the factor of luminescence depolarization (Y), the spin‐latice relaxation time (T1C) and for the nuclear Overhauser effect (NOE) of the 13C nuclei. The specific features of the behaviour of Y, T1C and NOE reflect the spectral characteristics of “longitudinal” and “transverse” relaxation processes.
The inhibited copolymerization of acrylonitrile with zinc acrylate in dimethylformamide solution
Authors: Czerniawski T. , Wojtczak Z. 
Published: April 2003

AbstractThe results of an investigation of the inhibited copolymerization of acrylonitrile with zinc acrylate in dimethylformamide are reported. Azobisisobutyronitrile and 2,2‐diphenyl‐1‐picrylhydrazyl were used as initiator and inhibitor, respectively. The obtained values of 2kdf = 1.60·10−5s−1 at 333 K and of the activation energy E = 127 kJ·mol−1 are within the limits of error to those obtained at the homopolymerization of acrylonitrile. This may be related to the large excess of acrylonitrile in the initial mixture with zinc acrylate.
Beitrag zur Anwendung der Methode Coazervativfraktionierung zur Herstellung von Fraktionen aus Polyethylen niederer Dichte im präparativen Maßstab
Authors: Braun D. , Rätzsch M. , Weber G. , Hofmann H. , Fiedler P. , Naumann O. 
Published: April 2003

AbstractGegenstand der vorliegenden Untersuchungen ist die Beschreibung und Anwendung der Coazervativfraktionierung zur Zerlegung von 500 bis 700g Polyethylen niederer Dichte. Die erhaltenen Fraktionen wurden durch Zahlen‐bzw. Gewichtsmittel der Molmasse, die Uneinheitlichkeit U und den Kontraktionsfaktor gß charakterisiert und können für Untersuchungen zur Struktur‐Eigenschafts‐Korrelation eingesetzt werden.
Investigation of poly(arylene vinylenes), 39. Synthesis of functionalized poly(1,4‐phenylene‐1,2‐diphenylvinylenes) by dehydrochlorination of unsymmetric p‐xylene dichlorides
Authors: Raabe D. , Hörhold H.‐H. 
Published: April 2003

AbstractHigh molecular weight (Mn > 20000) phenylsubstituted poly(phenylene vinylenes) were prepared via the dehydrohalogenation route, starting from unsymmetrically substituted p‐xylene dichlorides. The detailed synthetic procedures are given for poly(1,4‐phenylene‐1,2‐diphenylvinylene) Tg = 250°C, poly[1,4‐phenylene‐1(4‐chlorophenyl)‐2‐phenylvinylene] Tg = 253°C, and poly[1,4‐phenylene‐1(4‐benzoylphenyl)‐2‐phenylvinylene] Tg = 223°C. All of these are thermostable polymers, which are soluble in common organic solvents and can be processed to amorphous thin films.
Hydrogels based on 2.2.3.3.4.4.4.‐heptafluorobutyl methacrylate
Authors: Koßmehl G. , Volkheimer J. , Schäfer H. 
Published: April 2003

AbstractHydrogels (crosslinked polymers with a defined content of water) from hydrophilic methacrylates and perfluorobutyl methacrylate were prepared by radical polymerization, followed by swelling in buffered isotonic sodium chloride solution. The obtained hydrogel samples have been characterized by their linear expansion to hydration, weight‐percent hydration, refractive index, extractables, percent transmission of visible light, and oxygen permeability. Such hydrogels are interesting as contact lens materials.
Aromatic poly(oxadiazole)s ‐ new aspects of their synthesis, structures and properties
Authors: Schulz B. , Leibnitz E. 
Published: April 2003

AbstractAromatic poly(oxadiazole)s are a class of heterocyclic polymers that show excellent thermal and chemical stability. Also, their electrical and optoelectrical properties are of interest. Here, a short review is given about recent results in the field of aromatic poly(oxadiazole)s elaborated in our research groups that emerged from the former Institute of Polymer Chemistry in Teltow‐Seehof. New aspects are described regarding the technology of poly(oxadiazole) synthesis via the oleum route. In detail the structures of poly(p‐phenylene‐1,3,4‐oxadiazole) in solution as well as in solid state are described. Moreover, the electrochemical behaviour and the dynamic‐mechanical properties are discussed.
Partial structure factor analysis of neutron reflectometry from spread monolayers of isotactic polymethyl methacrylate
Authors: Henderson J. A. , Richards R. W. , Penfold J. , Thomas R. K. 
Published: April 2003

AbstractNeutron reflectivity data for isotactic polymethyl methacrylate monolayers spread at the air‐water interface have been analysed using the kinematic approximation. For surface concentrations up to 1.0 mg m−2 the data are well modelled by a uniform layer of thickness circa 20Å. Water may be uniformly dispersed throughout the film. However, to obtain agreement with the experimental reflectivities, a proportion of air must be included in the film which agrees with the findings of an earlier optical matrix type analysis. For surface concentration above 1 mg m−2, the uniform layer model does not reproduce the surface concentrations and the data is better fitted by a layer with a Gaussian distribution of segments in the aqueous phase. The benefits of the kinematic approximation are that an insight into the organisation of polymers at the air‐water interface can be obtained rapidly without the need for detailed fitting procedures inherent in the use of optical matrix methods.
Nanophases consisting of individual polystyrene molecules on mica imaged with scanning electron microscopy
Authors: Shelden R. A. , Meier L. P. , Caseri W. R. , Suter U. W. , Hermann R. , Müller M. 
Published: April 2003

AbstractScanning electron microscope images are presented of mica surfaces treated with an initiator and heated in the presence of styrene to obtain a grafted polymer. These images show “droplets” of size corresponding to that of individual polystyrene molecules. Other experimental evidence is presented which suggests that the droplets are indeed individual molecules. The images are believed to be the first ever obtained of individual, “tethered” synthetic polymer molecules.
Fibrillar and microfibrillar structures in poly(p‐phenylene terephthalamide) fibers
Authors: Wang W. , Ruland W. , Cohen Y. 
Published: April 2003

AbstractThe microfibrils and the microfibrillar network in poly(p‐phenylene terephthalamide) (PPTA) fibers formed during the coagulation from a monodomain lyotropic fiber are stabilized by critical point drying and characterized by electron microscopy and small angle X‐ray scattering. The diameter of the microfibrils varies from 20 to 49 nm depending on the PPTA concentration in the lyotropic solution used for the spinning. A formation mechanism for the microfibrils and the microfibrillar network is suggested. During the coagulation, the spinodal decomposition (phase separation) is assumed to occur before the crystallization (phase transition), resulting in the formation of the microfibrils. The formation of the microfibrillar network is considered to be related to the misorientation of macromolecules and the density fluctuation in the cross‐section of the filament during spinodal decomposition.
Modeling sustained oscillations in continuous emulsion polymerization of vinyl chloride
Authors: Tauer K. , Müller I. 
Published: April 2003

AbstractA simple mathematical model for the continuous emulsion polymerization of vinyl chloride based on nonlinear ordinary differential equations for the variation of particle concentration, total particle volume, and water‐soluble oligomeric products was developed and used to investigate which reactions influence whether or not sustained oscillations of latex properties occur at high conversion steady state. Results of the calculations are in good qualitative agreement with experimental data. Specifically, numerical analysis showed that the occurrence of sustained oscillations depends on particle coalescence as well as on the conversion dependence of both particle volume growth rate and particle coalescence rate. The model makes it possible to calculate the dynamic behavior of continuous emulsion polymerization reactors with regard to latex properties such as particle concentration, mean particle size, latex surface tension, solid content, and degree of coverage of latex surface with emulsifier from the start‐up into a high conversion steady state.
Miscibility behavior of ternary polymethacrylate‐based blends
Authors: Perrin P. , Prud'homme R. E. 
Published: April 2003

AbstractThe miscibility behavior of ternary poly(vinyl chloride)/poly(n‐propyl methacrylate)/poly(n‐amyl methacrylate) (PVC/PPMA/PAMA) and poly(vinyl chloride)/poly(n‐butyl methacrylate)/poly(n‐amyl methacrylate) (PVC/PBMA/PAMA) blends was investigated by differential scanning calorimetry. In both systems, a binary mixture of the two polymethacrylates is totally immiscible (PPMA with PAMA, and PBMA with PAMA). For PVC/PPMA/PAMA blends containing less than 70% PVC, the immiscible phase consists of two coexisting binary PVC/PPMA and PVC/PAMA phases. For an equal amount of the two polymethacrylates in the ternary blend, the PVC/PPMA phase contains 65% of the total weight of PVC and the whole quantity of PPMA; the total amount of PAMA mixes with the remaining 35% PVC to form the PVC/PAMA phase. In contrast, the miscibility zone is predominant in the ternary PVC/PBMA/PAMA system, since blends containing 30% or more of PVC exhibit a single glass transition temperature. In the immiscibe zone, the PVC is distributed equally between PBMA and PAMA, which is in contrast to the 65%‐35% distribution found in the previous system. These results are consistent with the differences of miscibility observed in the binary PVC/polymethacrylate blends discussed.