bluuebunny/crossref_metadata_2025_split huggingface dataset:
Graft polymerization of 4‐vinylpyridine onto cellulosic fibres by the ceric ion method, I. The reaction time effect
Authors: Leza M. Lourdes , Casinos Ismael , Guzmán Gonzalo M. , Bello Antonio 
Published: April 2003

AbstractA study was made of the time affecting the ceric ion induced grafting of 4‐vinylpyridine (4‐VP) onto partially carboxymethylated cotton (PCMC) having different degrees of substitution (D.S.). For comparison the same monomer was grafted onto cotton and mercerized cotton. The grafting parameters of these copolymerization reactions were determined. The graft yields for PCMC were significantly higher than those for unmodified cotton and mercerized cotton. The degree of crystallinity of the graft copolymers and of the unmodified cotton and PCMC samples was determined by the X‐ray method. The crystallinity index decreased with the presence of grafted polymer. The reaction time effect of the grafting of 2‐VP on cotton was also studied.
Light induced polymer and polymerization reactions, 35. Influence of monomer structure and binder composition on the photoinduced polymerization of multifunctional acrylic esters
Authors: Timpe Hans‐Joachim , Strehmel Bernd 
Published: April 2003

AbstractPhotocalorimetry, differential scanning calorimetry and ESR‐spectroscopy were used to analyse the photoinduced polymerization of multifunctional acrylic esters in various polymeric binders. Limiting conversion, maximal polymerization rate, inhibition time, and the time necessary to reach the maximum of the polymerization reaction rate were used to compare the reactivity of the photopolymer systems investigated in this work. Significant correlations exist between the limiting conversion and chemical structure of the acrylic esters used. A relation was also found between the glass transition temperature and oxygen permeability of the binder and the limiting conversion measured calorimetrically. A good correlation does not exist for the other reactivity parameters, because other factors such as phase change and changing diffusion conditions can have a complex influence on those values.
Oberflächenstrukturierung polymerer fasern durch UV‐laserbestrahlung. 6. Zur vermeidung von vergilbungen bei der laserbehandlung von polymeren
Authors: Knittel Dierk , Schollmeyer Eckhard 
Published: April 2003

AbstractEs wird gezeigt, daß die Ausbildung einer Schicht von verfärbenden Lasercrackprodukten – wie sie bei der Laserbehandlung von trockenen Polymeren gebildet wird – durch Imprägnierung mit verschiedenen Lösungsmitteln während der Laserbearbeitung verhindert werden kann. Die Ausbildung einer laserinduzierten Mikrostrukturierung der Polymeroberfläche wird davon nicht beeinflußt. Es läßt sich damit auch bei stärkeren Energiedichten der Laserbehandlung ein hoher Weißgrad aufrechterhalten.Zur Verhinderung der Vergilbung sind Wasser, Alkohole, Ether und wäßrige Tensidlösungen als Imprägniermedien während der Laserbestrahlung vorteilhaft einsetzbar.
Matériaux composites à base de bois retifié II. Etudes des propriétés mecaniques de differents mélanges
Authors: May J. F. , Guyonnet R. , Bourgois J. 
Published: April 2003

AbstractDivers matériaux composites à base de bois de pin rétifié ont été préparés. Leurs propriétés mécaniques sont comparées à celles des matériaux composites développés a l'aide de charges minérales (oxyde de zinc, silicate de magnésium, verre) ou organique (farine de pin naturel) et de matrices apolaires (polypropyléne) ou polaires (polychlorure de vinyle, poly(acrylonitrile‐butadiéne‐styrene)) pour différents taux de charges. Le comportement des melanges varie avec la nature du polymére: amélioration des propriétés mécaniques avec le bois rétifié et les resines polaires. Une généralisation de I'interprétation de ces différences de comportement, basée sur l'existence d'intéractions fibre‐matrice, est proposée. Des mesures de gonflement et de reprise de masse en milieu humide des composites préparés confirme l'interêt de l'utilisation du bois rétifié comme charge des matiéres plastiques polaires.
Solution properties of polyacrylic esters. II. Evaluation of unperturbed dimensions
Authors: Penzel Erich , Goetz Norbert 
Published: April 2003

AbstractAccording to existing well‐known theories unperturbed dimensions can be calculated from light scattering and viscosity measurements. The statistical segment Am proposed by Kuhn is a good measure for the flexibility of an unperturbed polymer coil. With the data reported in part I of the dependence of the radius of gyration and the Staudinger index, respectively, on the molecular weight, Am was calculated for nine polyacrylic esters and poly(acrylic acid). Poly(acrylic acid) with Am = 13,6 Å has the highest flexibility. The stiffness of the polymer chain is increased with growing C‐number of the alcohol. Branching in the alcohol further increases the stiffness of the polymer chain.
Analysis of the linear methods for determining copolymerization reactivity ratios, VIII. A critical reexamination of radical copolymerization of methylmethacrylate or styrene
Authors: Braun Dietrich , Czerwinski Wojciech K. , Tüdős Ferenc , Turcsanyi Béla , Kelen Tibor 
Published: April 2003

AbstractThe reactivity ratios of selected methylmethacrylate or styrene copolymerisation systems have been reviewed in terms of the extended Kelen‐Tüdős method. r‐values, together with their 95% confidence limits have been calculated. Quantities δ and Q, suitable for classification of the systems, have been applied. Of the 71 reevaluated methylmethacrylate systems 40 (56.3%) were found to belong to class I and 20 (28.2%) to class I(!), i. e. 60 (84.5%) systems for which the conventional copolymerisation equation was found to be adequate. For 3 (4.2%) systems belonging to class II the two‐parameter model does not hold and 8 (11.3%) systems were related to class III, i. e. systems for which the experimental data are inconsistent and the published r‐values meaningless. 32 styrene copolymerisation systems were reevaluated with the following classification: 19 (59.4%) systems in class I, 5 (15.6%) systems in class I(!), 2 systems in class II and 6 (18.8%) in class III.
A new approach to welding and lamination of polyamides
Authors: Avramova Nadka , Fakirov Stoyko 
Published: April 2003

AbstractAn attempt is made to provide a simple and inexpensive method for the lamination of polyamides. A new application of a known reaction – methoxymethylation of polyamides – is proposed: creation of chemical bonds at the interfacial boundary between two contacting surfaces, i. e. welding and lamination of polymides. Commercial polyamide‐6 films are used in this study. As a result of the creation of methylene bridges between neighboring amide groups welding of the films takes place. After the pressing for 30 h of films coated in a methoxymethylation solution, the welding is so strong that during the mechanical tests, instead of delamination, breaking of the films outside the overlapped area occurs.
Studies of the surface structure of plasma‐modified fillers and their application in PVC and PP compounds
Authors: Cai Shide , Ji Gending , Fang Jianglin , Xue Gi 
Published: April 2003

AbstractFillers for PVC and PP compounds have been treated by microwave plasma. FT‐IR photoacoustic spectroscopy studies show that the plasma polymer sheath on filler's surface contains CC, CH2, CH3 groups, etc. X‐ray photoelectron spectroscopy studies reveal that interfacial chemical bondings exist between silica and the organic coating. Application of plasma‐treated fillers in PVC and PP compounds gives rise to materials of good mechanical properties and low cost.
SBS/VP homograft membrane for oxygen enrichment
Authors: Yang Jen‐Ming , Hsiue Ging‐Ho 
Published: April 2003

AbstractThe grafting of 4‐vinyl pyridine (VP) onto styrene‐butadiene‐styrene triblock copolymers (SBS) by homografting irradiation with dissolved oxygen was studied. Homograft membranes of various degree of grafting were prepared from a casting solution of grafted copolymer in benzene. The mechanical properties of membranes, gas permeability, and the effect of operating temperature on gas permeation were investigated.The degree of grafting of 8.4% was the largest at an irradiation time of about 15.5 h. It was smaller at both shorter and longer duration because of the interference of dissolved oxygen. It was found that the tensile strength and elongation of SBS‐g‐VP were similar to those of SBS. The stress relaxation of SBS‐g‐VP was slower than that of SBS, and this might be due to the formation of rigid microphase separation domain of poly(4‐vinyl pyridine), which acted as permanent crosslinking points to reduce the stress relaxation.Using the properties of high flux of SBS and high O2/N2 selectivity of poly(4‐vinyl pyridine), the performance of gas permeation of 4‐vinyl pyridine homografted SBS membrane was studied. The selectivity of SBS‐g‐VP membrane increased with increasing degree of grafting. However, it was done at the expense of a decrease in the gas permeability.When the operating temperature of gas permeation increased, the permeability of oxygen and nitrogen increased, and the O2/N2 permeability ratio decreased. The activation energy (Ep) for gas permeation through different degree of grafting of SBS‐g‐VP membrane (obtained by the Arrhenius law) increased with increasing degree of grafting. For ungrafted SBS membrane, Ep was 5.5 kcal/mol for oxygen and 7.2 kcal/mol for nitrogen. For 8.4% grafting degree SBS‐g‐VP membrane, Ep for oxygen and nitrogen, were 6.5 and 8.1 kcal/mol, respectively.
Optische Methoden zur Charakterisierung von hochpolymeren Fasern. 2. Kennzeichnung von Oberflächen durch Specklemeßmethoden.
Authors: Eickmeier Achim , Bahners Thomas , Kleemann Wolfgang , Schollmeyer Eckhard 
Published: April 2003

AbstractDie Oberflächenrauheit ist eine der wesentlichen Eigenschaften textiler Materialien, die sowohl deren Gebrauchs‐ als auch Verarbeitungsverhalten beeinflußt. Die vorgestellten Specklemeßmethoden sind kohärent‐optische Streulichtmeßmethoden, die zur integralen, berührungslosen und zerstörungsfreien Erfassung von Oberflächenstrukturen herangezogen werden. Die Untersuchungen werden mit Verfahren der Specklekontrastmessung und der Korrelation dichromatischer Specklemuster durchgeführt. Sie erstrecken sich auf transparente Dielektrika (Mattglas, Plexiglas und Polyester folie), um zunächst sicherzustellen, daß die Eigenschaften der Specklefelder auch für Hochpolymere erhalten bleiben. Als Ausblick wird die Anwendung von Specklemeßmethoden auf textile Werkstoffe in den drei Ebenen Filament bzw. Faser, Garn und Gewebe diskutiert.
Urease immobilized polyethylene‐g‐acrylic acid membrane for urea sensor
Authors: Hsiue Ging‐Ho , Wang Chee‐Chan , Chen Chin‐Yun , Chang Chi‐Jung 
Published: April 2003

AbstractA new type of polymer support for immobilizing urease was investigated. The starting copolymers which grafted acrylic acid onto polyethylene (PE‐g‐AA) were prepared via gamma ray irradiation induced grafting under controlled conditions by postirradiation procedures. The optimum conditions for coupling urease to PE‐g‐AA were established and the physical properties of the support affecting the immobilized enzyme activity were studied.A water soluble carbodiimide (CMC) was used as a condensing agent to immobilize urease. The activities of the resulting enzyme membranes were very high. The hydrophilicity of the support and the activity of the enzyme membrane were proportional to the degree of grafting. Its linear detecting range was 60–400 ppm.
A search for optimal acrylic carriers for immobilization of penicillin acylase
Authors: Kolarz Bożena N. , Trochimczuk Andrzej , Bryjak Jolanta , Wojaczynska Maria , Dziegielewski Kazimierz , Noworyta Andrzej 
Published: April 2003

AbstractAcrylic carriers were obtained by aminolysis of nitrile or ester groups in copolymers or terpolymers synthesized from acrylonitrile, acrylic esters and divinylbenzene or ethylene dimethacrylate in the presence of a mixture of inert diluents. The influence of the supermolecular structure of these carriers, generated during the suspension polymerization by adding a mixture of inert diluents, on the carrier properties was observed. Acrylic carriers for immobilization of penicillin acylase should be obtained from either porous or ‘sol’‐type copolymers which aquire after aminolysis the structure of expanded gel.
The effect of conditions of mixing of polypropylene/ethylene‐propylene elastomer blends on their morphological structure and impact strength
Authors: Fortelný Ivan , Michálková Danuše , Koplíková Jaroslava , Navrátilová Edita , Kovář Josef 
Published: April 2003

AbstractThe dependence of morphological structure and notch impact strength of polypropylene/ethylene‐propylene elastomer blends on conditions of mixing was investigated. Two types of polypropylene and two types of ethylene‐propylene elastomer having different viscosities were used. At low rates and short times of mixing the samples contain both regions showing fine dispersion and regions showing large elastomeric inclusions surrounded with pure polypropylene. With increasing rate and time of mixing the large inclusions gradually disappear. The conditions of mixing which are necessary for reaching a homogeneous structure of the blends depend on viscosities of the components. The independence of particle size of the rate of mixing in homogeneous samples is discussed on the basis of a dynamic equilibrium between the break up and coalescence of droplets. The notch impact strength of the individual samples of the same blend is determined by the size and number of inhomogeneities (large inclusions) in the given sample.
Stress relaxation behaviour of liquid crystalline solutions of ethyl celluloses with different molecular weight in m‐cresol
Authors: Suto Shinichi , Sasaki Kiyoo , Tateyama Shinichiro 
Published: April 2003

AbstractThe stress relaxation behaviour of liquid crystal‐forming ethyl celllulose (EC) solutions in m‐cresol was determined by means of a cone‐plate type viscometer at 30°C. The effect of molecular weight (MW) on the behaviour was also determined. The relaxation behaviour could be fitted with the following equation:

where σi and σf are steady‐state shear stresses at shear rate \documentclass{article}\pagestyle{empty}\begin{document}$\dot \gamma _{\rm i}$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$\dot \gamma _{\rm f}$\end{document}, σ(t) is time‐ dependent stress, A1 and A2 are constants, τ1 and τ2 are relaxation times, t is time, and tc is a characteristic time. When log σ* was plotted against time, one straight line was obtained for isotropic solutions, whereas anisotropic solutions yielded two straight lines. This suggests that the liquid crystalline solutions have two separate relaxation processes: Process 1 has a relatively short relaxation time, and process 2 has a long one. The parameters τ1, τ2, and A2 were greatly dependent on polymer concentration, combination of \documentclass{article}\pagestyle{empty}\begin{document}$\dot \gamma _{\rm i}$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$\dot \gamma _{\rm f}$\end{document}, and MW, whereas A1 was independent thereof and was close to unity. The process 1 was supposed to be valid for individual molecules, and process 2 for liquid crystalline domains or randomly aggregated or entangled molecules.
Einige offene Fragen in der Rheologie der Polymerschmelzen
Authors: Wagner Manfred H. 
Published: April 2003

AbstractDieser Beitrag, der sich auf die Rheologie homogener, isotroper Polymerschmelzen beschränkt, gibt eine zusammenfassende Darstellung wesentlicher Erkenntnisse bei der Entwicklung einer rheologischen Zustandsgleichung und weist auf zwei offene Fragestellungen hin, die z. Z. Themen aktueller Forschung sind. Diese sind erstens der Zusammenhang zwischen linear‐viskoelastischem Relaxationszeitspektrum und dem molekularen Aufbau einer Polymerschmelze, und zweitens die Formulierung einer rheologischen Zustandsgleichung für allgemeine biaxiale Dehnungen.
Synthesis and characterization of ethylenediaminecellulose‐poly(glycidyl methacrylate) anion exchanger
Authors: Abou‐Shosha M. H. , Ibrahim N. A. 
Published: April 2003

AbstractThe synthesis of ethylenediamine‐cellulose‐poly(glycidyl methacrylate) anion exchanger was achieved by the reaction of ethylenediamine with cellulose‐poly(glycidyl methacrylate) copolymer. The effect of time, temperature, epoxy content, liquor ratio, ethylenediamine concentration and percent neutralization of the amine by acetic acid is reported. Reaction conditions were selected to synthesize an anion exchanger having a capacity of 196 meq/100 g. Potentiometric titration showed that this exchanger is a weak base anion exchanger having a pKb of 8.4, and its replaceable groups consisted of about 37.5% as primary amino groups and 62.5% as a mixture of both secondary and tertiary amino groups. Durability to use as well as water solubility of the prepared exchanger were investigated.
FTIR‐ATR study of interactions in polymer blends containing polyesterurethane
Authors: Sack Stephan , Haudel Gottfried 
Published: April 2003

AbstractMolecular interactions such as especially hydrogen bondings are considered to play a key role in polymer compatibility. In this study binary blends produced by extrusion of a MDI based segmented polyesterurethane (TPU) together with styrene‐acrylonitrile and acrylonitrile‐butadiene‐styrene copolymers, respectively, could be investigated without additional sample preparation using the infrared spectroscopic sampling technique of attenuated total reflection (ATR). With increasing content of the nitrile group containing polymers in the blends urethane carbonyl groups completely hydrogen bonded in the pure TPU are liberated. “Free” NH groups, however, are not detectable in the NH stretching region of the ATR spectra of the blends. The interpretation of the obtained spectral effects occurring in the blends is supported by experiments with N‐butyl‐carbamideacid‐methylester as model compound with an urethane linkage. The presented results lead to the conclusion, that intermolecular hydrogen bonding involving urethane NH groups and nitrile groups of the other polymers in the blends has been arised. Quantitative differences of these interactions between the two kinds of blends investigated in this study are discussed.
X‐ray scattering investigations of acrylonitrileethylene oxide block copolymers
Authors: Kwiatkowski Ryszard , Wlochowicz Andrzej , Wódka Tadeusz 
Published: April 2003

AbstractWide angle (WAXS) and small angle (SAXS) X‐ray scattering studies are reported on block copolymers of acrylonitrile with ethylene oxide. A distinct structural similarity between the copolymers and acrylonitrile homopolymer has been found. Considerable porosity of the copolymers has been shown. The porosity very largely governs the scattering power. It was found that the pores are three dimensional “particles” (scattering exponent α = 4), probably with smooth surfaces (surface fractal dimension ds = 2).
Beziehungen zwischen herstellung, struktur und mechanischen eigenschaften bei elastmodifizierten, schlagzähen styrolpolymeren
Authors: Michler Goerg H. , Hamann Bernd , Runge Jürgen 
Published: April 2003

AbstractKautschukhaltige Polystyrole mit unterschiedlichem Schlagzähigkeitsniveau, hergestellt durch Variation der Polymerisationsbedingungen, wurden hinsichtlich ihrer Morphologie und Zähigkeit eingehend untersucht. Auf der Grundlage transmissionselektronenmikroskopischer Strukturuntersuchungen wurden charakteristische Merkmale der Kautschukteilchen ermittelt und sechs Strukturtypen definiert. Mit Hilfe der Untersuchung gedehnter dünner Proben in einem 1000 kV‐Höchstspannungs‐Elektronenmikroskop wurden mikromechanische Prozesse, insbesondere die Craze‐Bildung, die die Eigenschaft der Zähigkeit vor allem bestimmt, analysiert. Die quantitative Auswertung dieser Untersuchungen führte nicht nur zu einer qualitativen, sondern auch zueiner quantitativen Korrelation zwischen der Größenverteilung der Kautschukpartikel und der Zähigkeit der Proben.
Untersuchung der molmassenverteilung von harnstoff‐formaldehyd‐leimharzen durch GPC gekoppelt mit lichtstreuung
Authors: Billiani Johann , Lederer Klaus , Dunky Manfred 
Published: April 2003

AbstractEs wurden UF‐Harze mit verschiedenen Kondensationsgraden durch unterschiedlich lange saure Kondensation hergestellt und mittels Gelpermeationschromatographie (GPC), gekoppelt mit einem Kleinwinkel‐Laserlichtstreugerät (LALLS), untersucht. Aus den Konzentrations‐ bzw. Lichtstreukurven kann die jeweilige Molmassenfunktion IgMw(V) sowie das Molmassengewichtsmittel berechnet werden. Dieses steigt mit fortschreitender Kondensation analog zur Trübungstemperatur der einzelnen Kondensationsstufe deutlich an und liegt im Bereich von einigen Tausend bis über 100000g/mol. Zusätzlich wurde festgestellt, daß in UF‐Harzen Molmassen bis ca. 500000g/mol enthalten sind; dabei handelt es sich offensichtlich um Aggregate, die nicht nur durch physikalische Wechselwirkungen hervorgerufen werden.
Grafting of 2‐(dimethylamino)ethyl methacrylate on linear low density polyethylene in the melt
Authors: Song Zhiqiang , Baker Warren E. 
Published: April 2003

AbstractGrafting of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) on linear low density polyethylene (LLDPE) in the melt has been studied through measurements of monomer conversion, the degree of grafting and the grafting efficiency. Results show that the grafting of DMAEMA on LLDPE can be carried out in the melt at temperatures as low as 90°C even though the melting point of the LLDPE is as high as 120°C. When the grafting reaction is carried out at too low or too high temperature, a low degree of grafting is observed. High reaction temperature favoured crosslinking of the polymer as indicated by decreasing melt flow index. Most of the grafts were obtained during the early period of the reaction (before 3 min under the reaction conditions used). Further increase in reaction time increased crosslinking and also produced more homopolymer, thus decreasing the grafting efficiency. Organic peroxides are effective initiators for the grafting reaction over a broad range of half‐lives while azo initiators do not produce grafting.
Thermal degradation of poly(vinyl chloride) blends
Authors: Braun Dietrich , Böhringer Bertram , Knoll Wolfgang , Eidam Norbert , Mao Weiyou 
Published: April 2003

AbstractPoly(vinyl chloride) was mixed with various poly(methacrylate)s and polycarbonates by combined precipitation from common solutions. The thermal stability of the samples was measured at 180°C under nitrogen, the HCl evolved was detected by conductometry.UV‐Vis‐spectra of degraded samples were measured to investigate the influence of the poly(methacrylate)s on the lengths of polyenes formed during the degradation of poly(vinyl chloride).The experiments show that the nature of the ester group is the dominating factor for the thermal stability of poly(vinyl chloride) in these blends. Poly(n‐butylmethacrylate) exhibits the best stabilization for poly(vinyl chloride) in this series. Polycarbonates with a higher glass transition temperature than the temperature of degradation destabilize poly(vinyl chloride).Stabilization experiments with dibutyltin‐bis(isooctylthioglycolate) show a costabilizing effect of the poly(methacrylate)s and polycarbonates.
Herstellung von dispersionen anionischer polyurethane mit COO− ‐gruppen und NH ‐gegenionen
Authors: Lorenz O. , Brocker J. , Haulena F. 
Published: April 2003

AbstractIn Dispersionen aus anionischen Polyurethanen, die das Triethylammoniumsalz der 2,2‐Dimethylolpropionsäure als Kettenverlängerungsmittel enthalten, läßt sich durch Zugabe von Ammoniak eine weitgehende Verdrängung des Triethylamins erreichen. Aus elektrostatischen Gründen ist nämlich in den in der Sternschen Schicht lokalisierten Ionenpaaren NH fester gebunden als NH(C2H5). Bei der thermischen Behandlung der Filme tritt Basenabspaltung ein, dabei erfolgt die Abgabe von Ammoniak deutlich schneller als die von Triethylamin. Die Spannungswerte der mit teilmethyliertem Hexamethylolmelamin vernetzten Proben sind daher um so höher, je mehr Triethylamin durch Ammoniak ersetzt wurde.