bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modified starch‐natural rubber blend, I. Cyanoethylation of xanthated starch
Authors: Hota Arun K. , Adhikari Basudam , Maiti Mrinal M. 
Published: April 2003

AbstractCommon wheat flour starch was subjected to xanthation followed by cyanoethylation at various levels of carbon disulfide and acrylonitrile to prepare modified starchnatural rubber masterbatches. Mutual influences of the extents of equilibrium xanthation and cyanoethylation on each other have been studied. The results have been explained on the basis of a definite interaction between xanthate group and free acrylonitrile in which both the steric factors and higher electrophilicity of acrylonitrile lead to the decomposition of xanthate groups and reduced the extent of cyanoethylation.
Aktivkohle aus Phenolharz mit gepreßten Olivenkernen als Füllstoff
Authors: Simitzis Johannis 
Published: April 2003

AbstractEine neue Aktivkohle wurde aus Phenolharz (Novolak‐Typ), gefüllt mit gepreßten Olivenkeren, hergestellt. Letztgenanntes Material ist ein landwirtschaftliches Nebenprodukt, das in großen Mengen jährlich hauptsächlich in Mittelmeer‐Ländern anfällt. Beide Materialien wurden in verschiedenen Verhältnissen gemischt, gehärtet und bis 1000°C carbonisiert. Der Gewichtsverlust und die Schrumpfung der Proben beim thermischen Abbau wurden gemessen. Die spezifische Oberfläche der kohlenstoffhaltigen Rückstände in verschiedenen Formen (z. B. als Pulver oder zylindrische Körper) wurde bestimmt. Die Adsorptionsfähigkeit der hergestellten kohlenstoffhaltigen Materialien in Bezug auf den Farbstoff Methylenblau in wäßrigen Lösungen wurde untersucht, und es wurde festgestellt, daß der Adsorptionsprozeß gemäß der Freundlich‐Gleichung stattfindet.
Oberflächenspannung von Poly(n‐butylmethacrylat)‐und Poly(n‐butyl‐ran‐methylmethacrylat)‐Schmelzen
Authors: Pigłowski Jacek 
Published: April 2003

AbstractDie Oberflächenspannungen sowie die Temperaturkoeffizienten der Oberflächenspannung von Poly(n‐butylmethacrylat) und zweier Copolymerisate aus Methylmethacrylat und Butylmethacrylat wurden im Temperaturbereich zwischen 180 – 230°C untersucht. Das Vorhandensein von Butylmethacrylatsequenzen in den Copolymeren senkt deutlich die Oberflächenspannung. Die Konsequenzen dieses Verhaltens für die Verwendung von Methacrylatcopolymeren als Verarbeitungshilfsmittel für Hart‐PVC werden diskutiert.
Verträglichkeit zwischen Methacrylat‐homo‐ und Copolymeren
Authors: Pigłowski Jacek , Kozłowski Marek 
Published: April 2003

AbstractDie Mischbarkeit von verschiedenen Systemen aus Polymethylmethacrylat (PMMA), Polybutylmethacrylat (PBMA) und Poly(methylmethacrylat‐co‐butylmethacrylat) (P(MMA‐co‐BMA)) wurde untersucht. PMMA und PBMA sind miteinander nicht mischbar. Die untersuchten Homopolymeren und entsprechende Methacrylatcopolymere bilden ebenfalls heterogene Systeme. Einphasige Mischungen aus PMMA und PBMA sind nur über Copolymerisation erreichbar.
Ethylene insertion with soluble Ziegler catalysts. III. The system cp2TiMeCl/AlMe2Cl/13C2H4 studied by 13C‐NMR spectroscopy. The time‐development of chain propagation and oligomer distribution
Authors: Mynott Richard , Fink Gerhard , Fenzl Wolfang 
Published: April 2003

AbstractThe development of the oligomer distribution during the polymerization of 13C‐enriched ethylene by the soluble Ziegler catalyst system Cp2 TiMeCl/AlMe2Cl was followed by 13C‐NMR spectroscopy. The assignment of the signals from the growing chains is described in full. It is shown that the rate of consumption of ethylene and Cp2 TiMeCl and the rate of formation of new chains can be monitored directly from the spectra. The concentrations of Ti‐propyl and Ti‐pentyl species during the polymerization were followed spectroscopically; both attain a steady state concentration. The relative rates were determined for the insertion of ethylene in the Ti‐carbon bond of Ti‐Me, Ti‐Pr and Ti‐Pe. These results give a detailed insight into the way that the oligomer distribution develops and provide a basis for its computer simulation. They also provide an independent proof that the dynamic model for the mechanism of ethylene polymerization with soluble Ziegler catalysts of the type Cp2 TiRCl/AlRnClm is correct.
Corrélations entre les propriétés viscoélastiques d'un composite verre‐epoxy et la présence d'un agent de pontage amino‐silane à la surface des fibres
Authors: Chauchard J. , Chabert B. , Jeanne P. , Nemoz G. 
Published: April 2003

AbstractDynamic, mechanical, and thermal properties were determined for unidirectional glass fibre reinforced resins. By an out axis study, it is possible to show the particular influence of a silane coupling agent on the mechanical and physical properties of composites. This agent increases the modulus of elasticity, the relaxation times, and the apparent activation energy in the rubbery state.
Synthesis and thermal stability of polyesters and polyamides fromβ‐(2‐methoxy‐5‐methylphenyl) glutaconic acid, diols, and diamines
Authors: Mehta Ashok M. , Dave Harshad R. , Patel Rajni M. 
Published: April 2003

AbstractSome polyester and polyamide resins were prepared by condensing β‐(2‐methoxy‐5‐methylphenyl) glutaconic acid with diols and diamines. The polycondensates were characterized by IR, TG, DSC, VPO, and elemental analysis. Some polycondensates were found to be soluble in acetone, dimethylformamide, and dioxane. All polymers were found to decompose in the range of ≈200 to ≈600°C. Their softening points are in the range of ≈ 90 to ≈ 190°C. They are brown black in colour. The kinetics of decomposition were studied. The kinetic parameters were evaluated by the method of Broido. It is observed that the energy of activation of polycondensates depends upon the presence of diol and diamine components in the polymer.
Effects of reaction conditions on bromination of atactic poly(propylene)
Authors: Mukherjee Ananda K. , Mohan Anita 
Published: April 2003

AbstractEffects of various reaction conditions on bromination of atactic poly(propylene) (APP) in carbon tetrachloride solution were studied. It was found that with the increase of the reaction time the extent of bromination increases. Also with an increased dilution of APP the rate of bromination increased following a bromination order of 0.66 with respect to APP concentration. This has been ascribed to initial replacement of the hydrogen at the tertiary carbon atoms followed by enhanced ease of abstraction from the neighbouring secondary and primary carbon atoms. The apparent activation energy was found to be 11.9 kcal/mol. The rate of bromination increases with an increase of the APP: Br2 molar ratio up to 1 : 1, beyond which the rate becomes independent of this ratio. Mechanism of bromination appears to be an initial substitution of tertiary H‐atoms by bromine radicals followed subsequently by replacement of secondary and primary H‐atoms via either progressive substitution or elimination‐addition. IR spectra confirm the presence of bromine in the samples.
Reactive olefinic copolymers. New developments and applications
Authors: Hert Marius , Guerdoux Lionel , Lebez Jean 
Published: April 2003

AbstractResearch work on reactive olefinic copolymers at CdF Chimie, has been followed since 1984 by the commercial development of a family of ethylene‐maleic acid anhydride (MAA) and acrylic ester terpolymers. These terpolymers cover a wide range of grades going from semi‐crystalline thermoplastics to elastomers, depending on comonomer content.Thus these products have found applications in various fields (coextrusion, lamination, toughening of blends, hot‐melts, powder coating etc.).Outstanding properties are obtained in several applications owing to the chemical reactivity of MAA with substrates in coextrusion and coating and with polymer matrices in blends. Chemical crosslinking, easy to perform with terpolymers, is a way to improve the high temperature mechanical properties (in wires and cables, pipes, hot‐melts etc.).
Influence of grafting on the thermodynamic parameters and stability constants of some intermacromolecular complexes of poly(methacrylic acid) and a graft copolymer
Authors: Chatterjee Saroj Kumar , Yadav Jai Bhagwan , Sethi Kuldip Raj 
Published: April 2003

AbstractStability constants and thermodynamic parameters (e.g. ΔH° and ΔS°) have been determined for intermacromolecular complexes of poly(methacrylic acid) and poly(acrylamide) (PAm)/poly(vinyl alcohol) (PVA) graft copolymer. These values have been compared with those obtained for the intermacromolecular complexes of corresponding homopolymers (e.g. PAm and PVA). Influence of grafting on these parameters has been explained on the basis of more favourable cooperative binding with the graft copolymer.
Analytische Untersuchung einer Polymerlegierung aus Polyamid und Ethylencopolymeren
Authors: Braun D. , Illing W. 
Published: April 2003

AbstractAus Polyamid 6 (PA 6) und einem Copolymeren aus Ethylen und Acrylsäure (EAA) wurde im Gewichtsverhältnis 90/10 eine Polymerlegierung in einem Zweiwellenextruder unter dem Einfluß von hohen Scherkräften und Temperaturen hergestellt. Das entstandene Mehrphasensystem aus PA 6, EAA und Pfropfcopolymeren wurde durch REM‐Aufnahmen, DTA, GPC, IR, NMR, Extraktion mit für die Ausgangsprodukte spezifischen Lösungsmitteln und Bestimmung der reaktiven Gruppen untersucht.
Collagen‐based bioadhesive barnacle cement mimic I. Chemical and enzymatic studies
Authors: Kaleem K. , Chertok F. , Erhan S. 
Published: April 2003

AbstractA biomedical adhesive that can bind to calcified tissues without drying and prior acid etch has been developed. The adhesive was prepared from commercially available gelatin, by first modifying its backbone to increase its phenolic content. This was achieved by reductive alkylation using phenolic aldehydes. Gelatin, modified this way, functions as a substrate for polyphenol oxidase and crosslinking takes place. A concentrated solution of gelatin and the enzyme, together with amines, can bond bone slices.
Matériaux Composites à Base de Bois Rétifié: Contribution à i'Etude des Propriétés Rhéologiques à i'Etat Fondu en Régime Stationnaire
Authors: Jaziri M. , May J. F. , Bourgois J. , Guyonnet R. 
Published: April 2003

AbstractL'étude des propriétés rhéologiques à l'état fondu de matériaux composites à base de farines de bois ou de bois rétifié et de polyéthylène basse densité apolaire ou de copolymères d'éthylène polaires, a été effectuée à différentes vitesses de cisaillement. Le comportement des mélanges varie avec le degré de torréfaction du bois et la nature polaire ou apolaire de la matrice. Une interprétation de ces différences de comportement, basée sur les interactions fibres‐matrices, a été proposée. Des mesures d'essais mécaniques, effectuées sur des éprouvettes composites, confirment les résultats présentés à l'état fondu.
Synthesis of chiral polymers with pendant aminobornanol derivatives
Authors: Liu Jui‐Hsiang 
Published: April 2003

AbstractA series of diastereoisomeric amino bicyclo [2,2,1] heptane derivatives was synthesized from ( + )‐camphor. Further treatment of aminobornanols with triethyl orthopropionate yielded chiral oxazolines, which were found to be efficient for the asymmetric induction of carboxylic acids. Synthesis and polymerization of the new chiral oxazolinebornyl methacrylates derived from aminobornanols was carried out. Effects of temperature, solvents, and molar ratio of the reagent on the synthesis of the linear chiral and of the insoluble cross‐linked chiral polymers were also discussed.
Radical copolymerization and terpolymerization of 1,1,2,3,4,4‐hexafluoro‐1,3‐butadiene with alkylvinyl ethers, alkenes, and methyl‐2,3,3‐trifluoroacrylate
Authors: Žůrková E. , Bouchal K. , Kálal J. , Chvátal Z. , Dědek V. 
Published: April 2003

AbstractCopolymere von 1,1,2,3,4,4‐Hexafluor‐2,3‐butadine (HFB) mit n‐Alkylvinylethern(AVE) (Alkyl = Butyl, Propyl, Ethyl and Glycidyl) order mit Alkenen wie isobuten, Ethylen and Propylen wurden durch radikalische Lösungscopolymerisation unter Verwendung von peroxidischen Neidertemperatureinition synthesiert. Die Polymerisation verlief nach radikalischem Mechanismus and wurse durde durch die Zugable vo 1,2‐Diphenyl‐2‐pikryl‐hydrazyl völling inhibiert. Die Anfangsgeschwindigkeit der Copolymerisation hing von der Gesamtkozentration der Monomeren and von von dem Verhältnis [HFB] zu [AVE] ab; die maximale Reaktiongeschwindigkeit wurde bei etea äquimolaren Konzentrationsverhältnissen der monomeren erzielt.Durch die untersuchung der Struktur der copolymeren HFB‐AVE wurde die alter‐neirende Anordnung der Hexafluorobutadien‐and Vinylethereinheinten in der Copolymerkette nachgewiesen. Durch die radikalische Lösungsterpolymerisation des Monomerensystems HFN‐AVE Methyl‐2,3,3,‐trifluoracrylet (MTFA) wurden Terpolymere des Typus–[HFB]x‐[AVE]y‐[MTFA]z –synthetisirt, deren Struktur einer alternierrenden Anordnung von Perfluor‐ (HFB and MTFA) and Vinylethereinheiten entspricht. Durch alkalische hydrolyse der Trifluoracrylateinheiten wurden die entsprechenden Terpolymeren der Triflurocrylsäure synthesiert.
Zur radikalisch initiierten Copolymerisation von Ethylen, I. Ethylen‐Propylen‐Copolymerisate
Authors: Payer Wolfgang 
Published: April 2003

AbstractWachsartige Copolymerisate aus Ethylen und Vinylacetat werden in der Mineralölindustrie als Fließverbesserer für Mitteldestillate eingesetzt. Es sollte geprüft werden, ob sich mit anderen analog zusammengesetzten Copolymeren die gleichen Effekte erzielen lasen. Hierzu wurde die Copolymerisation von Ethylen und Propylen unter Drücken von 150 und 200 MPa bei Temperaturen von 160 und 200°C untersucht.Die Initiierung der Reaktion gelingt problemlos durch Peroxide, wobei mit steigendem Propylen‐Anteil im Reaktionsgemisch eine Erhöhung der Initiatormenge erforderlich ist. Die mittlere Molmasse der Produkte ist vom Propylen‐Gehalt abhängig. Sie kann darüber hinaus durch die Verwendung von Kettenübertragungsmitteln gezielt eingestellt werden. Die Ethylen‐Propylen‐Copolymerwachse zeigten im Vergleich zu den analog zusammengesetzten Ethylen‐Vinylacetat‐Copolymerwachsen nur eine begrenzte Wirksamkeit als Fließverbesserer in Mitteldestillaten.
Depolarization current of novolac phenol‐formaldehyde resins doped with 1,4‐diazabicyclo [2.2.2] octane
Authors: Topić Mladen , Moguš‐Milanković Andrea , Katović Zvonimir 
Published: April 2003

AbstractMixtures of novolac phenol‐formaldehyde (NPF) resins and 1,4‐diazabicyclo [2.2.2] octane (DABCO) were polarized at different temperatures applying different d. c. electric fields. Thermally stimulated depolarization current (TSDC) measurements performed from 298 to 373 K showed a dipolar α peak and a space charge α peak as in pure NPF. The addition of DABCO decreases the magnitude of the α peak and the activation energy of the dipolar relaxation but increases the background current and the magnitude of the α peak significantly. The maximum of the α peak is only slightly shifted towards higher temperatures. New aspects in the analysis of the background current by consecutive heating and cooling experiments are considered. The results obtained show an increase in concentration of trapping sites due to the heterogeneity of the mixed systems. The proposed interactions between nitrogen from DABCO and hydroxy groups from NPF are discussed.
Determination of ethylene‐propylene rubber in crosslinked blends with 1,4‐polybutadiene
Authors: Hummel Klaus , Stelzer Franz , Hobisch Gerald , Hartmann Barbara 
Published: April 2003

AbstractCrosslinked blends of ethylene‐propylene rubber (EPR) and 1,4‐polybutadiene (BR) were investigated by metathesis degradation of the BR component; the percentage of EPR was determined by weighing the polymeric residue. The metathesis reaction was carried out with an excess of 1‐octene in the presence of the catalyst WCl6/(CH3)4Sn. In crosslinking with dicumyl peroxide, the best results were obtained with 10 to 30 wt.‐% of EPR and medium crosslinking degrees. Analysis of sulphur vulcanizates (received with the accelerator N‐cyclohexyl‐2‐benzothiazyl sulphenamide) gave tolerable results only for low sulphur contents (1.5 wt.‐%). Determination of EPR was also possible in non‐crosslinked blends with BR.
Fließverhalten von Mischungen aus chloriertem Polyethylen und Polymethylmethacrylat
Authors: Braun P. , Mennig G. , Paredes E. 
Published: April 2003

AbstractDas Fließverhalten von Mischungen aus chloriertem Polyethylen (PEC) und Polymethylmethacrylat (PMMA) wird in Form von Fließkurven dargestellt. Die Ergebnisse der rheologischen Messungen werden anhand der sich ausbildenden Morphologie diskutiert. Es zeigt sich, daß die untersuchten Mischungen aus PEC/PMMA mit Chlorierungsgraden bis 40 Gew.‐% Cl das charakteristische Verhalten von unverträglichen (2‐phasigen) Mischungen mit teilweise fein dispergierter zweiter Phase liefern. Vergleichend wird die Stoffkombination PE/PMMA betrachtet, wobei die PE‐Sorten jeweils die unchlorierten Ausgangsprodukte darstellen. Der Einfluß der Chlorierung auf das Fließverhalten und die zweiphasige Struktur ist deutlich festzustellen.
The laser flash‐initiated polymerization as a tool of evaluating (individual) kinetic constants of free radical polymerization, 3. Information from degrees of polymerization
Authors: Olaj Oskar Friedrich , Bitai Irene 
Published: April 2003

AbstractEquations are derived for the number average and the weight average degrees of polymerization for the polymer forming in a laser‐initiated photo‐polymerization under pseudostationary conditions when termination occurs by disproportionation or recombination and if chain transfer is negligible. Analysis of the degrees of polymerization at various pulse separations leads to information on the rate coefficient of propagation (kp) and on the product kt ρ (kt = rate coefficient of bimolecular chain termination, ρ = concentration of primary radicals produced in each flash). As kp2/kt may be evaluated from the rate and the weight average degree of polymerization P̄w of a single pseudostationary experiment, at least in principle, a complete resolution into individual constants may be achieved. It is demonstrated in an example that the data obtained in this way for the polymerization of styrene at 25°C are well consistent with those originating from other methods.
Gemeinsame Kondensation von Harnstoff, Melamin und Formaldehyd. II. Modellreaktionen
Authors: Braun Dietrich , Ritzert Hans‐Josef 
Published: April 2003

AbstractAnhand von Modellreaktionen von teilweise blockierten Melamin‐ und Harnstoff‐derivaten mit Formaldehyd wurde die gemeinsame Kondensation von Harnstoff, Melamin und Formaldehyd studiert. An den Modellsystemem Harnstoff/Benzoguanamin/Formaldehyd und Dimethylharnstoff/2‐Amino‐4,6‐di‐(N‐methylanilin)‐1,3,5‐triazin/Formaldehyd konnten mit Hilfe der Gelchromatographie, IR‐Spektroskopie und Thermogravimetrie chemische Brücken zwischen den Triazin‐ und Harnstoffkomponenten, also Cokondensate, festgestellt werden.Auch beim System Harnstoff/Melamin/Formaldehyd konnten durch Pikratfällung der Triazinkomponenten und Urease‐Spaltung dieses Niederschlages Cokondensate nachgewiesen werden.
Small‐angle X‐ray investigations of defined multiblock (b‐styrene‐bisphenol a carbonate) copolymers
Authors: Włochowicz Andrzej , S̀lusarczyk Czesław , Strobin Grażyna , Dems Andrzej 
Published: April 2003

AbstractThe separation of phases in defined multiblock (b‐styrene‐bisphenol A carbonate) copolymers was analyzed by small‐angle X‐ray scattering. It was found that these copolymers form typical microdomain structures. For copolymers containing 0.34 and 0.47 wt.‐parts polycarbonate (PC) the microdomains are arranged in the face‐centred cubic macronetwork. The distance between domains decreases with increasing concentration of polycarbonate. The copolymer containing 0.767 PC has lamellar structure. The thickness of the domain‐boundary interphase was quantitatively estimated by analyzing a systematic deviation of the scattering curves at large angle tail from the Porod's law. The thickness of the transition layer decreases with increasing concentration of polycarbonate.
Antioxidants and stabilizers, 107. Reaction of N‐phenyl‐1,4‐benzoquinoneimine with the 1‐cyano‐1‐methylethyl‐radical
Authors: Taimr Luděk , Prusíková Miluše , Hanuš Vladimír , Pospíšil Jan 
Published: April 2003

AbstractThe reaction of N‐phenyl‐1,4‐benzoquinoneimine (I)Decoding of abbreviations see p. 103/104.
and 4‐hydroxydiphenylamine (II) with the carbon centred 1‐cyano‐1‐methylethyl radical (R·) was studied in connection with an investigation of the action mechanism of industrial antidegradants, such as N‐phenyl‐N′‐sec‐alkyl‐1,4‐phenylenediamines. The mixture of I and II reacts very readily with R·, giving rise to III, VI, and VIII. I alone reacts much slowlier, and the reaction mixture contains more products. IV and VII were identified along with III. Under the conditions used, II alone does not react at all. IV exists in two isomeric forms, syn and anti. VIII is very labile; XI was isolated from its transformation products. Reduction of IV gives V, which is labile, similarly to VIII.
On the structure of macroreticular styrene‐divinylbenzene copolymers
Authors: Poinescu Ignat , Vlad Cristina , Carpov Adrian , Ioanid Aurelia 
Published: April 2003

AbstractThe influence of the removal of various diluents, pore forming agents from the porous styrene‐ethylstyrene‐acrylonitrile‐divinylbenzene copolymers on the structure of the matrix was investigated by several methods. The most advantageous pathway to preserve the initial structural edifice of the porous networks performed in the presence of solvating diluents consisted in the removal of the inert media with methanol as it was noticed from the experimental data. If the steam treatment is applied, the collapse effect takes place and the anion exchangers prepared from such matrices exchange/adsorb less dye stuff by comparison with ones formed from beads treated with methanol, because the pore size was changed. It was also noticed that the porous copolymers performed in the presence of the solvating diluents (mixtures of solvatings and precipitants) swell very well in methanol though it is a precipitating medium for the polystyrenic macromolecular chains.
Ozoninduzierter Abbau von Polyoxymethylen
Authors: Braun D. , Müller I. 
Published: April 2003

AbstractProben von unstabilisiertem und mit den Antiozonantien N‐Isopropyl‐N′‐phenyl‐p‐phenylendiamin (IPPD) und Bis‐(1,2,3,6‐tetrahydrobenzaldehyd)‐pentaerithrityl‐acetal (Vulkazon AFS) stabilisiertem Polyoxymethylen wurden unter mechanischer Belastung in einer Klimakammer ozonisiert. Die Schädigungen auf der Oberfläche wurden IR‐spektroskopisch und rasterelektronenmikroskopisch untersucht. Während der Ozonisierung von POM bildet sich eine geschädigte Schicht, deren Dicke mit zunehmender Ozonisierungszeit wächst. Hierbei wird das Polymere an den Acetalbindungen angegriffen, wodurch Ketten gespalten werden und Oligomere entstehen.
Heat stability of styrene‐zinc acrylate copolymers
Authors: Włochowicz Andrzej , Eder Marek 
Published: April 2003

AbstractThe dependence of glass temperature on the heating rate and the composition for styrene‐zinc acrylate copolymers has been investigated by differential scanning calorimetry. Thermogravimetry was used in order to examine these copolymers undergoing pyrolysis in an atmosphere of air at three different heating rates. Thermal decomposition of ionomers is a three‐stage process. The orders and activation energies have been determined for each stage of decomposition using the computer programs based on the methods of Kissinger, Freeman‐Carrol, and Ozawa. It was found that the heat stability is lowered by the ionic groups.