bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationships between mechanical properties and microhardness of polyethylenes
Authors: Lorenzo Vicente , Pereña José Manuel , Fatou José María G. 
Published: April 2003

AbstractThe values of the elastic modulus (E) and the yield stress (Y) and the shape of the strain‐stress curves of different polyethylenes have been related to the microhardness (MH) of these materials, considering the roles that the crystalline, amorphous, and interfacial regions play in the deformation of semicrystalline polymers. Linear relations between microhardness and degree of crystallinity, (1 – λ)d, and between the logarithms of E and MH have been found. The variations of the parameters 100Y/E and σmin/Y (σmin is the relative minimum value of the nominal stress for elongations above the yield point) as a function of (1–λ)d follow different trends for linear and branched polyethylenes. Moreover, it has been found that the ratio MH/Y is smaller than three for these materials, approaching this theoretical value (Tabor relation) only for the highest crystallinity levels.
Ein modell zur quantitativen beschreibung der morphogenesis von PVC‐S, IV. Berücksichtigung der hüllenbildung und modellanwendung
Authors: Henschel Ines , Platzer Bernd , Weickert Günter 
Published: April 2003

AbstractBeim PVC, das nach dem Suspensionsverfahren in Rührbehältern hergestellt wird, bildet sich (bedingt durch die Tropfenrotation) eine Hülle aus dicht zusammengelagerten Partikeln um das PVC‐Korn. In der vorliegenden Arbeit wird das in vorherigen Artikeln1–3 vorgestellte Modell der Morphogenesis von PVC‐S um diese Vorgänge erweitert. Die Modellparameter werden abgeleitet, und es wird die Anwendbarkeit des Modells durch Vergleich seiner Ergebnisse mit rasterelektronenmikroskopischen Meßwerten nachgewiesen. Es ist in der Lage, die Veränderungen mehrerer Hierarchieebenen der inneren Morphologie über den gesamten Umsatzbereich nachzubilden.
Gelpermeationschromatographie von anionischen polyurethan‐dispersionen
Authors: Lorenz O. , Brocker J. , Gerhard H. , Haulena F. , Roeder D. 
Published: April 2003

AbstractEs wird über die Gelpermeationschromatographie (GPC) weitgehend monodisperser PMMA‐Latices sowie anionischer Polyurethan‐Dispersionen mit unterschiedlich breiter Teilchengrößenverteilung (TGV) unter Verwendung eines Copolymeren aus Oligoethylenglycol, Glycidylmethacrylat und Pentaerythroldimethacrylat (Fractogel TSK) als Säulenfüllmaterial berichtet. Das Elutionsvolumen des Peak‐Maximums sowie die Peak‐Breite sind von der Ionenstärke des Elutionsmittels abhängig. Die TGV der Dispersion wurde außerdem durch Ultrazentrifugation bestimmt. Wie bei den PUR‐Dispersionen gezeigt werden konnte, entspricht das Peak‐Maximum des GPC‐Diagramms dem Zahlenmittel des Partikeldurchmessers D̄N bzw. dem D50‐Wert (Durchmesser, bei dem 50% der Masse erfaßt sind). Lösungsmittel und andere Additive, die in den PUR‐Dispersionen enthalten sein können, lassen sich ebenfalls durch GPC identifizieren.
Flüssigkristalline hauptkettenpolyester mit trans‐1,4‐cyclohexyleneinheiten
Authors: Braun Dietrich , Schülke Ulrike 
Published: April 2003

AbstractDas flüssigkristalline Verhalten von Polyestern aus trans‐1,4‐Cyclohexylen‐bis(4‐hydroxybenzoat) und Alkandicarbonsäuren wird mit Hilfe der Differentialkalorimetrie (DSC), der Mikroskopie und der Röntgenstrukturanalyse untersucht. Ein Vergleich der Daten aus Viskositätsmessungen und der Gelpermeationschromatographie (GPC) gibt Aufschluß über die Molekulargewichte der Polyester.Die Synthese und Charakterisierung eines neuen, ähnlich aufgebauten Polyesters aus alternierenden Cyclohexylen‐ und Phenylenringen wird beschrieben.
Intumescent fire retardant systems: Effect of fillers on char structure
Authors: Bertelli G. , Marchetti E. , Camino G. , Costa L. , Locatelli R. 
Published: April 2003

AbstractScanning electron microscopy and microanalysis by energy dispersive system show that the structure of the foamed char obtained on burning polypropylene fire retarded with an intumescent additive system, can be strongly modified in the presence of typical inorganic fillers. Modifications involving both the physical and chemical characteristics of the char might be related to chemical reactions between fillers and acid phosphorus moieties of the fire retardant. Fillers that modify the structure of the char tend to decrease the efficiency of the fire retardant system.
Heat resistant polyamideimides, 3. Synthesis, characterization, and evaluation of thermal and other properties
Authors: Ghosh Malay 
Published: April 2003

AbstractPolyamideimides have long been known for their excellent heat resistance properties. This paper will report the synthesis of two new polyamideimides from 4,4′‐bis‐(3‐carboxylphthalimidyl)biphenyl and/or 4,4′‐bis‐(3‐chlorocarbonylphthalimidyl)biphenyl and two aromatic diamines by using solution polycondensation reaction at low temperature in polar organic solvents. The optimum conditions necessary for the polycondensation reaction have been studied. Characterization of polymers is done by elemental analysis, IR data, and viscosity measurements. The prepared polymers are partially soluble in electron donating organic solvents for example dimethyl formamide, dimethyl acetamide, m‐cresol etc. In addition to heat resistance properties of polymers, chemical stability towards acid and base and moisture absorption properties have been evaluated.
The influence of pore dispersion and polymer/surface interaction on peak dispersion phenomenon in size exclusion chromatography
Authors: Omorodion S. N. E. , Hamielec A. E. 
Published: April 2003

AbstractBased on the newly proposed instrumental spreading shape function (ISF) of Omorodion and Hamielec1 and the new theoretical developments on peak dispersion phenomenon2, the present study reported herein deals with some of the non‐inherent contributing sources to peak dispersion phenomenon in SEC. Despite when the choice of a suitable mobile phase has been accomplished for a particular polymer/packing material system3–5, the need to optimize the system for minimum peak broadening is still very important. The major contributing sources discussed here are the roles of pore dispersion (large pores) and polymer/small pore‐size surface area interactions resulting from the traditional method of column arrangements. The systems employed in the study are dextran/mostly CPG systems. Other packing materials employed included Bio‐glass (BG) and EM‐gel (EM), both of large pore size range.
Crosslinking of polyethylene photoinitiated by benzoquinones and naphthoquinones
Authors: Zamotaev Pavel V. , Luzgarev Sergey V. 
Published: April 2003

AbstractCrosslinking of polyethylene (PE) photoinitiated by some benzoquinones and naphthoquinones has been studied. The quantum yields (φ) of the initiator reactions in PE under UV irradiation were measured. The φ‐values for benzoquinone, tetrachlorobenzoquinone, tetrabromobenzoquinone, tetrafluorobenzoquinone, naphthoquinone, and 2,3‐dichloronaphthoquinone were equal to 0.23, 0.18, 0.14, 0.26, 0.09, and 0.11, respectively. Naphthoquinones were more effective as initiators in photocrosslinking of polyethylene.
Modification of wood fiber surface by grafting and its effect on mechanical properties of polystyrene filled system
Authors: Raj R. G. , Kokta B. V. , Daneault C. 
Published: April 2003

AbstractPolystyrene (PS) was reinforced/filled with grafted thermomechanical pulp (TMP) of aspen and birch. The dependence of tensile properties of composites on different loadings of filler, on polymer loading in grafted fiber, on the presence of homopolymer in grafted fiber, and on impregnation of fibers with PS were studied. PS filled with grafted aspen and birch (lower polymer loading) showed a significant increase in tensile strength and modulus. Fracture energy and elongation of the composites decreased with an increase in the concentration of filler.
Composite model calculation for the thermal expansibility of high density polyethylene
Authors: Bandyopadhyay Partha , Biswas Prabir K. , Basu Asok N. 
Published: April 2003

AbstractThe thermal expansibility of high density polyethylene is calculated within the framework of the composite model which has already been found useful in describing its mechanical properties and thermal conductivity. The orientational changes of the units of which the bulk of the polymer is supposed to be composed has been derived from a two parameter empirical relation proposed by the authors. A comparative study of the variation of the orientational parameters with processing conditions has also been included.
Immobilization of 2,4‐ionene on a macroporous poly(styrene‐divinylbenzene) resin and its effect on the rate of the cobaltphthalocyanine‐catalyzed oxidative coupling of mercaptoethanol
Authors: Van Streun Karel H. , Meuldijk Jan , German Anton L. 
Published: April 2003

AbstractA poly(quaternary ammonium) salt, 2,4‐ionene, has been immobilized on a macroporous chloromethylated poly(styrene‐divinylbenzene) resin (XAD‐2). The ionene content of the resin, determined by CHN elemental analysis, was 50.2 g/kg resin. The most important side effect of the modified resin, catalyst (2,4‐ionene) bleeding, can be detected by a spectrophotometric method capable of determining extremely low concentrations of free ionene in the supernatant of the resin.The activity of these immobilized 2,4‐ionene/cobalt(II)phthalocyanine‐tetrasodiumsulfonate (CoTSPc) complexes towards the oxidative coupling of thiols is much lower than in the homogeneous case, but still considerably higher than for the polymer free system. The observed decrease in reaction rate does not originate from the considerable mass transfer resistances but predominantly from catalyst properties like a very low local N+/Co ratio. The active sites appear to be present in the outer shell of the resin particles only.
Thermal and UV degradation of impact‐resistant polystyrene
Authors: Mlinac‐Mis̆ak M. , Jelenc̆ić J. , Bravar M. 
Published: April 2003

AbstractA commercial type of impact‐resistant polystyrene (IPS) was investigated. Two types of antioxidants, Irganox 245 and Irganox PS‐800 were added to IPS in amounts of 0.05 to 0.2%. Films, dumbbells and straight test pieces were subjected to thermal and UV ageing.Films of 250 μm thickness were thermally treated at 100°C and separately UV irradiated at 360 nm for 24, 72, 120 and 168 h. Dumbbells and straight test pieces were only thermally aged at 100°C for 7, 14, 21, 28 and 35 days.Carbonyl and hydroxy group content as well as polybutadiene‐(PB)‐unsaturation absorbances of films were measured by IR spectroscopy.Breaking strength, elongation and izod impact‐strength of test pieces were determined.
Molecular aggregation of PEEK with PES blends and the block copolymers composed of PEEK and PES components
Authors: Wu Zhongwen , Zheng Yubin , Yan Hongmao , Nakamura Tomoki , Nozawa Takafumi , Yosomiya Ryutoku 
Published: April 2003

AbstractPolymer blends of PEEK with PES were prepared by the solution blending method. Copolymers composed of PEEK and PES components were synthesized from these oligomers. The formation conditions exerted an influence over the molecular aggregation and the crystallization behaviors of the blend films and block copolymers which were examined by X‐ray diffractometry and DSC analysis. As a result, phase‐separation in the blend films was found when the formation temperature was high. The blend films formed at 340°C, quenched and annealed at 180°C, exhibited the same crystallization behavior as those of PEEK. In the case of the blend films formed at 300°C, the annealing of the films at 250°C was required to crystallize the blend films. The Tg of a copolymer with a PEEK component content of more than 50% tends to shift toward a higher temperature than the Tg of PEEK itself, and the Tm of the copolymer toward a lower temperature than that of PEEK ist.
XPS and SSIMS studies on CF4/O2 plasma treated polycarbonate
Authors: Occhiello E. , Morra M. , Garbassi F. 
Published: April 2003

AbstractXPS, SSIMS and water contact angle measurements have been used to characterize the chemical effect of CF4/O2 discharges on polycarbonate (PC) made from bisphenol A. We found that the surface modification induced by plasma treatment can be clearly explained on the basis of the acitve species present in the plasma, whose concentration has been studied by actinometry.With very low amounts of O2 in the gas feed (1%) extensive fluorination of the surface occurs, due to grafting of the fluorocarbon radicals. Perfluorinated islands are formed, as shown by the high value of advancing contact angles. In the 20–80% O2 range, fluorine atoms react with the surface, partially inducing etching. Low amounts of fluorine are observed on the sample and no perfluorinated islands. Oxygen participates in etching and oxidizes the PC surface. We observed an increase of the surface concentration of oxygen with increasing the O2 amount in the gas feed and also the formation of strongly oxidized islets on the sample surface, as shown by the dramatic reduction of receding contact angles. A reduction of surface aromaticity, observed by XPS and SSIMS, is the consequence of these reactions.
The photocopolymer rod of ethyleneglycol dimethacrylate with methylmethacrylate
Authors: Liu Jui‐Hsiang , Wang Jenn‐Hwa , Chu Ming‐Huei 
Published: April 2003

AbstractThe photocopolymerization of ethyleneglycol dimethacrylate (EGDMA) with methylmethacrylate (MMA) containing benzoin methyl ether (BME) as initiator was carried out in a glass tube to fabricate a light‐focusing plastic rod (radius Rp) with a parabolic refractive index distribution (distribution constant A) in the region near the center axis (radius Rc). The dependence of A and Rc/Rp on MMA/EGDMA feed ratio, influence of BME concentration on the refractive index distribution, and the reproducibilities of the photopolymerizations were investigated. The Rc/Rp increased with the feed ratio used under BME = 1.0 wt.‐% at velocity of UV lamp V = 0.58 mm/min. On the other hand, Rc/Rp increased with the feed ratio to 0.2 and then decreased remarkably with the feed ratio in the range of 0.2–0.25 with BME = 0.6 wt.‐% at V = 0.735 mm/min. Plastic rods fabricated in the investigation using photopolymerization have lens characteristics and good reproducibilities.
Effects of drawing conditions on the properties of optical fibers made from polystyrene and poly(methyl methacrylate)
Authors: Dvořánek Ladislav , Machová Luďka , Šorm Miloslav , Pelzbauer Zdeněk , Švantner Jiří , Kubánek Vladimír 
Published: April 2003

AbstractMonofilaments possessing various degrees of birefringence were obtained by changing the drawing rate, the molten polymer temperature, and the molecular weight of polystyrene (PS) and poly(methyl methacrylate) (PMMA). The “brittle‐toductile” transition point of optically pure PS was found in the range of birefringences of −0.6 · 10−3 to −2.6 · 10−3. Both the height and position of this point are influenced by M̄w, molecular weight distribution, and polymer melt temperature. The birefringence of PS is higher by two orders of magnitude than that of PMMA in which this transition point has not been observed. The mechanical and optical properties depend not only on the average amount of orientation characterized by the birefringence but on what portion of the relaxation spectrum of the polymer is preferentially oriented. During the drawing of PS and PMMA monofilaments crazes are formed in the centre of the fibers and do not reach the surface.
Temperaturabhängigkeit der ammoniak‐diffusion in polymerfilmen
Authors: Müller F. W. , Schiller K. , Jänchen U. , Marx J. 
Published: April 2003

AbstractDie Temperaturabhängigkeit der Ammoniak‐Diffusion in 14 transparenten filmbildenden Polymeren wurde zwischen 15 und 90°C mit Hilfe einer neuen absorptionsspektroskopischen Methode untersucht. Eine lineare Freie‐Energie‐Beziehung zwischen der Aktivierungsenergie der Diffusion (ED) und dem präexponentiellen Faktor der Arrhenius‐Gleichung (DO) entspricht dem Verhalten permanenter Gase im Glaszustand der Polymeren, die NH3‐Diffusionskoeffizienten sind jedoch im Mittel etwa eine Größenordnung kleiner. Wie ein Vergleich der Aktivierungsenergien für die Diffusion von Ammoniak und Sauerstoff in drei Polymeren zeigt, ist dafür nicht ein größerer effektiver Van‐der‐Waals‐Radius des NH3 verantwortlich, sondern die verminderte Aktivierungsentropie der Ammoniak‐Diffusion.
Elution behaviour of diolmodified epoxides in size exclusion chromatography
Authors: Tänzer Wolfram , Szesztay Márta , László‐Hedvig Zsuzsa , Fedtke Manfred , Tüdős Ferenc 
Published: April 2003

AbstractThe reaction of bisphenol A‐diglycidyl ether (BADGE) with butane‐1,4‐diol (BD) in the presence of Mg(ClO4)2 leads to linear and branched oligomers. The formation ratio of these products depends on the reaction temperature. In experiments at 100°C, an epoxide consumption of up to 70% can be observed using HPLC. In this range all products show good solubility in THF, so that it is possible to follow the increasing molar mass by using SEC. A characteristic relation of the molar mass against the conversion rate is derived and SEC data of a branched product are discussed.
Alternating electrical conductivity of polyphenylenes and their pyrolysis residues after doping
Authors: Simitzis J. , Boro I. , Hinrichsen G. 
Published: April 2003

Abstracto,m,p‐Polyphenylenes were prepared by oxidation‐cationic polymerization of biphenyl and then pyrolyzed up to 800°C. The o,m,p‐polyphenylenes as well as their pyrolysis residues were doped with anhydrous FeCl3 from their solution in acetonitrile. The real part of the alternating electrical conductivity σ′ of the undoped and doped materials was determined at room temperature.Decreasing σ′‐values of pyrolyzed residues at 600°C without doping were observed because of the large weight losses during the pyrolysis leading to chain scission reactions within the polymer. At higher pyrolysis temperatures (i.e. 700°C, 800°C) the σ′‐values are increased due to the formation of closed aromatic systems in the polymer. The doped materials have higher σ′‐values in relation to the corresponding specimens without doping, with the exception of the pyrolysis residues at 800°C. The dependence of doping effect and time was also determined. The transition of the organic polymer to the pyropolymers can be followed and characterized by the measurement of alternating electrical conductivity.
Ataktisches polypropylen als pfropfgrundlage für die monomeren vinylacetat und vinylchlorid. Herstellung undeigenschaften der pfropfprodukte
Authors: Schellenberg Jürgen , Hamann Bernd 
Published: April 2003

AbstractDie Möglichkeiten des Einsatzes von ataktischem Polypropylen als Pfropfgrundlage zur Herstellung von Pfropfcopolymerisaten des Vinylacetates und Vinylchlorids bzw. von Polypropylen‐Vinylacetat‐Pfropfprodukten als Pfropfgrundlage zur Herstellung von Pfropfcopolymerisaten des Vinylchlorids werden in Abhängigkeit von der Ausgangsgemischzusammensetzung untersucht.Nach Abmischung der Pfropfprodukte mit Polyvinylchlorid bzw. ABS/Polyvinylchlorid‐Mischungen werden ausgewählte mechanische Eigenschaften sowohl in Abhängigkeit von der Menge des enthaltenen Pfropfproduktes als auch von der Zusammensetzung der Pfropfpolymerisate dargestellt.
Synthesis of polyethylenes with high polydispersity
Authors: Luft Gerhard , Dorn Max 
Published: April 2003

AbstractFor a number of applications the use of polyethylenes with a high polydispersity is recommended. In order to prepare such grades polymerisation tests were performed in a stirred autoclave in laboratory scale. The autoclave was run continuously at 1800 bar in the range of 210 to 285°C with 60 s residence time. Difunctional peroxides with identical and with different substituents on both OO groups were tested. For comparison, monofunctional compounds from industrial processes were used. The concentration of the peroxides in the feed was varied between 3 and 60 mol ppm.By GPC, polydispersities of 5 to 9, comparable to those of commercial polyethylenes, were measured on the samples produced with the monofunctional peroxides. Distinctly higher polydispersities of up to 13 were achieved by the use of the difunctional peroxides, especially with the symmetrical compound.
Strukturuntersuchungen an PF/cellulosepapier‐verbunden mittels dynamisch‐mechanischer analyse
Authors: Döhring Dieter , Raubach Heinz , Singer Klaus , Jäkel Evelyn , Goering Harald 
Published: April 2003

AbstractEs wird versucht, für Verbunde aus mit Holzöl sowie Tricresylphosphat modifizierten Phenol‐Formaldehyd‐Polykondensaten und Cellulosepapier, die als Leiterplattenbasismaterial technisch in großem Umfang genutzt werden, mittels Torsionsschwingungs‐ und dielektrischer Messungen einen Zusammenhang zwischen dem strukturellen Aufbau und den Verbundeigenschaften herzustellen. Die innere Weichmacherwirkung von Holzöl wird diskutiert. Die Holzölmodifizierung bewirkt neben einer Flexibilisierung, daß durch Beseitigung sterischer Behinderungen ein größerer Umsatz der funktionellen Gruppen bei der Resitbildung erreicht und der Vernetzungsgrad im Vergleich zu einem unmodifizierten PF‐Hartpapier erhöht wird. Die Messungen zeigen, daß Tricresylphosphat als äußerer Weichmacher wirkt, der die zwischenmolekularen Wechselwirkungen herabsetzt.
Highly active peroxides in the radical polymerization of ethylene under high pressure — conversion and initiator usage
Authors: Luft Gerhard , Grimm Hubert , Dorn Max 
Published: April 2003

AbstractBy using highly active peroxides, it is possible to reduce the polymerization temperature necessary for the synthesis of low density polyethylene. In order to examine a number of peroxides for their suitability as low temperature initiators, polymerization tests were carried out at 1900 bar, 70–140°C, with an average residence time of 30 s in a continuously operating laboratory facility equipped with a stirred autoclave. Apart from a number of perneodecanoates, two peroxy dicarbonates, a sulphonyl peroxide, and a difunctional peroxide were used.The initiator consumption was high at polymerization temperatures below 100°C. The results obtained with the different peroxides varied considerably. As the temperature increased, the initiator consumption decreased rapidly to reach almost the same level for all the individual peroxides at above 120°C. The difunctional compound that proved highly suitable for the low polymerization temperatures desired was 1,4‐di‐(2‐neodecanoyl peroxy isopropyl)benzene, the consumption at 100°C of which amounted to 13 g initiator/kg PE. Using a quantity of 40 g initiator/kg PE, a reactor temperature of 82°C could be employed. The peroxy dicarbonates and tertiary butyl perneodecanoate gave less satisfactory results.
Melt flow and mechanical properties of sulfonated butyl rubber ionomers
Authors: Xie Hong‐Quan , Xu Ji‐Geng 
Published: April 2003

AbstractStudy of melt flow properties and mechanical properties of sulfonated butyl rubber ionomers showed that in the case of lithium ionomers addition of zinc stearate lowered obviously the melt viscosity, represented by torque value of a Brabender rheometer, and enhanced tensile strength of the ionomer up to 25% of zinc stearate, while in the case of ethylamine neutralized ionomer addition of zinc stearate lowered the melt viscosity not so obviously as in the case of lithium ionomer and slightly affected the tensile strength. Amine neutralized ionomers exhibited very low permanent sets, while the lithium ionomer showed much higher permanent set, which increased with sulfonate group and amount of zinc stearate added. Increase of neutralization degree below equivalent ratio of 1 significantly raised the melt viscosity and tensile strength.For monovalent cation ionomer, melt viscosity and tensile strength diminished with decreasing ionic potentials, but for divalent cation ionomers with increasing ionic potentials and with decreasing covalent character tensile strength decreased and melt viscosity increased.For different amine neutralized ionomers tensile strength decreased in the following orders: ethylamine > triethylamine > diethylamine; isopropylamine > ethylamine > tertiary butylamine > methylamine; ethylamine > hexylamine > dodecylamine > octadecylamine.