bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methacrylamide‐initiated graft copolymerisation of segmented polyurethanes
Authors: Egboh Sunday H. 
Published: April 2003

AbstractMethacrylamide, which had been stored over weeks after purification polymerized spontaneously in N,N‐dimethylformamide when left standing in sealed degassed glass ampoules for several days at room temperature. However, freshly purified methacrylamide did not polymerize under identical conditions. A free radical mechanism was postulated to account for these observations. Using the self‐initiated polymerisation of methacrylamide as free‐radical sources, poly(urethane‐g‐methacrylamide)s were synthesized. Some of the resulting graft copolymers were partially soluble in certain common organic solvents. The properties of the unmodified and graft copolymers were investigated. The graft copolymers were relatively more thermally stable than the original polyurethanes.
Polymeric phthalocyanines and their precursors, 4. Optimization of electrochemical properties of polyphthalocyanine modified titanium electrodes
Authors: Wöhrle Dieter , Bannehr Rüdiger , Schumann Bernd , Jaeger Nils 
Published: April 2003

AbstractPolyphthalocyanine (1) coatings on titanium foils were prepared by in situ synthesis starting from 1,2,4,5‐tetracyanobenzene (3). In order to optimize the electrochemical activity of the polymer modified electrodes several parameters, e.g. pretreatment of Ti‐foils, amount of 3, reaction temperature and time were varied. The layer of 1 was analyzed by UV/VIS‐ and IR‐spectroscopy. Electrochemical measurements were carried out in K3, K4 [Fe(CN)6] redox electrolyte. In comparison with a Pt‐electrode the polymer modified Ti‐electrodes show also high activity combined with stability. Electrodes prepared from other nitriles (4–8) were investigated in principle only.
Polypropylene modification by water‐soluble monomers in the presence of an emulsified water‐insoluble liquid phase
Authors: Citovický Pavol , Mikulášová Darina , Chrástová Viera , Mejzlík Jiří , Majer Josef 
Published: April 2003

AbstractLow‐oxidized isotactic polypropylene containing hydroperoxides as well as other more stable peroxides was prepared by a contact of polymeric powder with O2/O3 mixture and was further used for chemical modification by water‐soluble monomers, such as acrylamide or acrylic acid. The reaction is performed at 30°C in the system containing water, an emulsifier, ferrous chelate, and a water‐insoluble liquid phase. In the case of acrylic acid, the use of non‐polar compounds, such as n‐hexane and benzene, is preferred, while acrylamide polymerization requires the presence of polar compounds, such as ethylacetate or higher alcohols. The composition of individual components may be optimized to such an extent that the highly predominating product of polymerization is polypropylene with bonded polar polymer branches, the simultaneously proceeding homopolymerization being strongly suppressed.
Alkaline degradation of styrene‐acrylonitrile copolymers and formation of block copolymers
Authors: Severini Febo , Pegoraro Mario 
Published: April 2003

AbstractThe styrene‐acrylonitrile (SAN) copolymer, dissolved in dimethylsulfoxide (DMSO), has been degraded in the presence of some bases such as KOH and potassium‐t‐butoxide at room temperature. The addition of 4‐vinylpyridine or propyleneoxide which can be anionically polymerized, has led to the production of copolymers. Their composition has been studied by IR, elemental analysis, and fractionation techniques. The presence of groups in the degraded products has been explained by a scission mechanism which gives rise to anions useful for the formation of block polymers.
Verwendung neuer halogenpolyole zur PUR‐hartschaumerzeugung mit verminderter brennbarkeit
Authors: Marzec Krzysztof , Lesiak Tadeusz 
Published: April 2003

AbstractEs wurden Untersuchungen durchgeführt, inwieweit sich aus 2‐Furaldehyd erhaltenes 3,5‐Dibromhexan‐1,4‐diol, 3,5‐Dichlorheptan‐1,4‐diol, 3,5‐Dibromheptan‐1,4‐diol, 2‐(4,5‐Dichlorpentyl)propan‐1,3‐diol und 2‐(4,5‐Dibrompentyl)propan‐1,3‐diol zur Herstellung von PUR‐Hartschäumen mit verminderter Brennbarkeit eignen. Es wurde auch die Möglichkeit der Verwendung von Hexan‐1,4‐diol, Heptan‐1,4‐diol, 2‐(Pent‐4‐enyl)propan‐1,3‐diol und 6‐Hydroxymethylheptan‐1,2,7‐triol zur Herstellung von Polyurethan‐Schäumen untersucht.
Analytische Differenz‐IR‐Spektrometrie von Mehrkomponentenkunststoffen und Copolymeren. I. Identifizierung der Komponenten in Polymergemischen
Authors: Hummel D. O. , Votteler Christine 
Published: April 2003

AbstractDie Einführung computerunterstützter IR‐ und FTIR‐Spektrometer hat die Möglichkeiten der qualitativen und quantitativen Analyse von makromolekularen Mehrkomponentensystemen erheblich erweitert. Wenn die Forderung der spektralen Superposition erfüllt ist, läßt sich mit Hilfe gespeicherter Standardspektren der Komponenten durch Differenzspektrometrie die Zusammensetzung eines Systems ermitteln. Da diese Forderung sehr oft nicht erfüllt ist, wählt man für die Differenzspektrometrie eines Systems aus n spektral definierten Komponenten n Punkte aus dem empirisch zu ermittelnden optimalen Bereich im Innern des (n‐1)‐dimensionalen Gibbsschen n‐Ecks. Bei realen Polymergemischen mit kristallisierbaren Komponenten ist deren Kristallinitätsgrad niedriger als in den ungemischten Polymeren; dies ist wahrscheinlich auf gegenseitige Durchdringung der nichtkristallinen Bereiche zurückzuführen. Hochgefüllte Kunststoffe lassen sich differenzspektrometrisch noch gut identifizieren, wenn der Füllstoff monodispers ist (Zahnzemente). Organisch gefüllte Werkstoffe mit niederem Bindemittelanteil (Hartfaserplatten mit Holzschliff) lassen sich nur dann differenzspektrometrisch identifizieren, wenn die charakteristischen Absorptionen des Bindemittels in Bereichen liegen, in denen der Füllstoff nicht stark absorbiert. —Artefakte können ein differenzspektrometrisches Ergebnis verfälschen. Ursachen und Auswirkungen von Artefakten werden diskutiert.
Reaction of maleic anhydride and molten polystyrene in the absence and presence of peroxides
Authors: Gaylord Norman G. , Elayaperumal Piramiah 
Published: April 2003

AbstractThermomechanical degradation of polystyrene (PS) at 180° and 250°C resulted in main chain scission and a small decrease in the molecular weight, as measured by inherent viscosity. The lower molecular weight was retained in the presence of maleic anhydride (MAH) although the latter was incorporated into the PS. The presence of benzoyl peroxide and dicumyl peroxide in the molten PS resulted in a significant molecular weight reduction, due to disproportionation of the internal radicals generated by hydrogen atom abstraction from the PS backbone. The extent of peroxide‐induced degradation was greatly reduced in the presence of MAH which presumably added to the internal PS radicals before their disproportionation. The low MAH content of the reaction product despite the use of high concentrations of MAH and peroxides is attributed to the quenching of MAH excimers by PS.
Veränderung von Polyvinylidenfluorid durch Gammastrahlen
Authors: Orth Helmut 
Published: April 2003

AbstractVinylpolymere mit substituierter alpha‐Stellung erleiden üblicherweise bei Bestrahlung einen Kettenabbau ohne Vernetzung. Die vorliegende Arbeit zeigt aber, daß Polyvinylidenfluorid unter Einwirkung von Gammastrahlen und Luftsauerstoff offenbar stark vernetzt wird, daneben findet auch Kettenabbau statt.
Water‐insoluble dextran polymers by grafting of hydrophobic groups. I. Reaction with butyric anhydride and heterogeneous hydrolysis of the partially modified dextran
Authors: Sánchez‐Chaves M. , Arranz F. 
Published: April 2003

AbstractA study has been made on the modification reaction of dextran with butyric anhydride using pyridine as catalyst. The structures of the modified polymers were determined by means of IR and 1H‐NMR spectroscopy as well as by chemical analysis. It has been found a linear dependence of the reaction rate on the product of butyric anhydride and pyridine concentrations and a more complex dependence on the alcoholic groups concentration. The activation energy was found to be 7.0 kcal/mol. A partially modified dextran (D.S. 1.34) was hydrolyzed at several pH values and temperatures. The experimental data have been treated as a pseudo‐first‐order reaction with respect to the butyrate concentration. The activation energies obtained from the acid and base catalyzed hydrolysis reactions were 12.5 and 12.0 kcal/mol, respectively.
Untersuchungen zur Feinstruktur des PVC, V Herstellung von 1,2,6‐Trichlor‐n‐hexan als Modellsubstanz für niedermolekulares PVC
Authors: Schwenk Ulrich , Streitberger Horst , Weitze Renate , Wrackmeyer Bernd 
Published: April 2003

AbstractDurch Umsetzung von 1,2,6‐Trihydroxy‐n‐hexan (IV) mit Thionylchlorid entsteht 1,2,6‐Trichlor‐n‐hexan (II), welches als Modellsubstanz für 1H‐NMR‐, 13C‐NMR‐und massenspektrometrische Vergleiche mit durch Extraktion und Hydrierung gewinnbarem niedermolekularem PVC dient.
Model compounds for the urea‐formaldehyde condensation. 1. Methylenediurea
Authors: Braun Dietrich , Günther Peter , Romeira Stella Maris 
Published: April 2003

AbstractMethylenediurea was prepared in a manner slightly different from the methods mentioned in literature. The obtained product was characterized by chromatographic and spectroscopic methods. Hydrolyses were performed to investigate the dependence of reaction rate from pH and concentration of methylenediurea, which has been described formerly with more contaminated methylenediurea.
Graft copolymerization of acrylonitrile and acrylonitrile‐styrene onto carbon fibers containing unsaturated groups
Authors: Yosomiya Ryutoku , Fujisawa Takao , Kobayashi Masahiro 
Published: April 2003

AbstractGraft copolymerization of acrylonitrile and acrylonitrile‐styrene onto carbon fibers containing unsaturated groups was studied. Graft copolymerization of acrylonitrile was found to result in a very low grafting yield in comparison with styrene, and it remained nearly constant in the latter stage of the reaction. The effects of monomer concentrations, initiators, solvents, and reaction temperature on the monomer reactivity ratios were studied by using Hayes's equation to calculate the reactivity ratio.For graft copolymerization of acrylonitrile‐styrene were studied the rate of graft polymerization and the grafting yield with varying monomer compositions, both of which were found to be very low in the range of monomer compositions containing acrylonitrile at a level more than 8%. The monomer reactivity ratios for each monomer were calculated by use of the Fineman‐Ross method after the analytical determination of compositions of both grafted copolymer and ungrafted copolymer, and it was found that the monomer reactivity ratios for the grafted copolymer were very different from those for the ungrafted copolymer.
A porous glass fibre/resin composite: Structure, properties, and weather resistance
Authors: Järvelä Pentti K. 
Published: April 2003

AbstractThe structure and properties of a porous composite manufactured from glasswool and phenol‐formaldehyde resin with pressure and heat, were studied in a density range of 800 – 1500 kg/m3. Fibre structure of the composite is almost randomly orientated in two directions, and high open porosity is a typical property.Specific strength of the composite is high compared to other similar materials, but the composite is relatively brittle. The composite is very durable in a normal atmosphere in spite of the open porosity of the composite. Only freezing water and a large enough thermal shock are capable of breaking the composite structure.
Gemeinsame Kondensation von Phenol, Melamin und Formaldehyd, II. Chromatographische und spektroskopische Untersuchungen
Authors: Braun Dietrich , Krauße Walter 
Published: April 2003

AbstractDie gemeinsame Kondensation von Phenol, Melamin und Formaldehyd wurde bei unterschiedlichen Reaktionsbedingungen untersucht. Bei 100°C und pH 5 ist die Geschwindigkeit der Kondensation zwischen Melamin und Formaldehyd so extrem hoch, daß es nach wenigen Minuten zu unlöslichen, hochmolekularen Produkten kommt, die nicht mehr analysierbar sind. Bei niederigeren Temperaturen (z. B. 45°C) geht das Melamin nicht mit ausreichender Geschwindigkeit in Lösung. Daher ist es nicht moglich, bei pH 5 eine kontrollierbare Dreikomponentenkondensation durchzuführen. Im schwach alkalischen oder neutralen Medium und bei Temperaturen von 80 bis 100°C ist zwar eine kontrollierbare Umsetzung möglich, die gelchromatographischen Untersuchungen ergaben jedoch, daß das Phenol in den Reaktionsprodukten noch praktisch unumgesetzt vorlag. Lediglich einige Methylolphenole waren in sehr geringen Anteilen neben Methylolmelaminen und höhermolekularen Homokondensaten des Melamins nachweisbar. Diese Resultate wurden mit Hilfe der Dünn‐schichtchromatographie und der 13C‐NMR‐Spektroskopie bestätigt.
Effect of copolymers modifying PVC on its physical and mechanical properties and its UV‐radiation resistance, I. ESR investigation of UV‐irradiated PVC films containing MMA/MA, VC/VAC, MBS or ABS
Authors: Kaczmarek H. , Rozpłoch F. , Kamińska A. 
Published: April 2003

AbstractESR investigations of the concentration of radicals formed in UV‐irradiated PVC films containing 3 wt.‐% of one of the following copolymers MMA/MA, VCIVAC, MBS or ABS were carried out. The concentration of radicals in films containing the modifying copolymers was found to be several times higher than that in films of pure PVC. That was observed after an exposure time of 0.5, 1, 2, and 3 h. This points out that modifying copolymers considerably influence the UV‐resistance of PVC. Non‐uniform changes of the radical concentration observed in all the samples in the first stage of exposure point out that the yield of radical formation and radical desactivation is changing without domination of either of these processes. The equilibrium between these two kinds of processes was reached after longer exposure during the time apparently depending on the composition of sample.
Incorporation of ergotamine into un‐crosslinked poly(2‐hydroxyethyl methacrylate)
Authors: Huglin Malcolm B. , Sloan David J. 
Published: April 2003

AbstractA simple procedure is described for producing thin polymer/drug discs of predetermined thickness, surface area and drug load. Discs were cut after solvent evaporation from a film obtained by mixing separate ethanolic solutions of poly(2‐hydroxyethyl methacrylate) and ergotamine tartrate, the latter solution containing added tartaric acid to enhance drug solubility. Established partial degradation of drug was evidenced by the colouration developed during casting. However, the calculated drug content of a disc accorded well with the total ergotalkaloids content measured by fluorescence on completely released drug.
Polypropylen‐nadelkristalle in orientierten blends aus polypropylen und poly‐1‐buten: Fourieranalyse der röntgenweitwinkelstreuung
Authors: Wenig Werner , Hagenbeck Gisela 
Published: April 2003

AbstractDie laterale Dicke der Polypropylen‐Nadelkristalle in orientierten Blends aus Poly‐propylen (PP) und Poly‐I‐buten (PB‐1) wurde durch eine Analyse der Röntgenweitwinkelstreuung bestimmt. Die Nadeldicke nimmt von ca. 300 Å (Gewichtsmittel) bzw. 400 Å (Zahlenmittel) mit abnehmendem Polypropylenanteil auf ca. 100 Å ab. Mischkristalle, in denen sowohl PP‐ als auch PB‐1‐Ketten kristallisieren, werden nicht gefunden. Die Änderung der Nadeldicken mit der PP‐Konzentration erklärt die an den gleichen Proben gemessene Schmelzpunktsdepression. Die Gitterstörungen nehmen mit abnehmendem PP‐Anteil leicht zu. Sie sind im wesentlichen innerhalb einer lateralen Grenzschicht, deren Dicke nur wenig von der Nadeldicke abhängt, konzentriert.
Effect of copolymers modifying PVC on its physical and mechanical properties and its UV‐radiation resistance. II. Thermal stability of PVC films modified by MMA/MA, VC/VAC, MBS or ABS
Authors: Kamińska A. , Kaczmarek H. 
Published: April 2003

AbstractThermal stability of films made of PVC and blends of PVC and MMA/MA, VC/VAC, MBS or ABS was studied.It was found that 1% of VC/VAC in PVC films improves its thermal stability while the other copolymers impair it.Reverse effect, however, is observed in the test samples with increased content of copolymers from 1 to 10%. VC/VAC causes evident gradual decreases of dehydrochlorination temperature. The other copolymers cause its increase.Hence it is that the influence of modifying copolymers on thermal stability of PVC depends not only on the type but also on the quantity of copolymer. The reason is the changing of compatibility with concentration of both polymers and therefore the changing conditions of their interaction.
Effect of pre‐extension on the electrical conductivity of styrene‐butadiene rubber loaded with FEF carbon black. II. Electrical conductivity in transverse direction
Authors: Amin M. , Hassan H. H. , Nasr G. M. 
Published: April 2003

AbstractContinuing the previous work, the electrical conductivity, σ, of 70 phr FEF/SBR pre‐extended samples in the transverse direction is discussed in detail. The pre‐extension is a parameter which affects the anomalous behaviour which appeared as a minimum in the electrical conductivity σ vs. T curves. A correlation between the effect of pre‐extension on both the logitudinal and transverse direction has been done.The dielectric constant, ϵ′ and the dielectric loss, ϵ″, of the above mentioned pre‐extended sample in the transverse direction and their dependence on temperature was observed.
Die elektrische leitfähigkeit von α,ω‐bis‐polyenen
Authors: Patschorke Joachim 
Published: April 2003

AbstractDie Herstellung und Isolierung der farbigen Umsetzungsprodukte aus Maleinsäureanhydrid‐methylvinylether‐copolymerem (Gantrez AN) und aprotischen Flüssigkeiten führt zu α,ω‐Bis‐polyenen des Copolymeren mit jeweils gleichlangen Doppelbindungssequenzen, unabhängig vom Grad der Umsetzung. Der Polyenbildung in Hexamethylphosphorsäuretriamid (HMPA) geht eine chemische Umsetzung mit dieser aprotischen Substanz am Anhydridring des Gantrez AN voraus.Werden die entstandenen α,ω‐Bis‐polyene mit Jod, Dichlor‐dicyan‐p‐benochinon (DDQ), Tetracyanoethylen (TCNE) und Tetracyanochinodimethan (TCNQ) dotiert, findet eine Verbesserung der elektrischen Durchgangsleitfähigkeit statt. Die Behandlung des undotierten α,ω‐Bis‐polyens in siedendem Xylol, wie auch Press‐Sinterung, führt zu spezifischen Widerständen in der Größenordnung von Polyacetylen (PA). Insgesamt wird der spezifische Widerstand um zehn Größenordnungen reduziert, Gantrez AN: 2,8 · 1013 Ω · cm, press‐gesintertes α,ω‐Bis‐polyen: 1,1 · 104 Ω · cm, joddotiertes α,ω‐Bis‐polyen: 2 · 103 Ω · cm.Mit Hilfe der IR‐Spektroskopie ist es möglich, den Nachweis der Polyen‐ und Komplexbildung zu erbringen und schließlich zu zeigen, daß das leitfähigkeitsaktive Umsetzungsprodukt ein 3‐ bzw. 4‐substituiertes α,ω‐(Bis‐polyen‐)‐1,2‐polybuten ist.
Synthesis, characterization, and thermal behaviour of glycidyl methacrylate‐2‐ethoxy ethyl acrylate copolymers
Authors: Dhal Pradeep K. , Babu Gaddam N. 
Published: April 2003

AbstractCopolymerization of glycidyl methacrylate has been carried out with 2‐ethoxy ethyl acrylate in bulk at 60°C using benzoyl peroxide as the initiator. The copolymer composition has been determined by chemical analysis as well as from 13C‐NMR data. The monomer reactivity ratios were calculated by using YBR method. The number average sequence length of the copolymers has been determined from 13C‐NMR data and compared with those obtained from reactivity ratios. The intrinsic viscosities of the copolymers were determined in DMF and the thermal properties of the copolymers were evaluated.
The kinetics of formation of diethylene glycol in preparation of polyethylene terephthalate and its control in reactor design and operation
Authors: Renwen He , Feng Yan , Tinzheng He , Shiming Geng 
Published: April 2003

AbstractThe kinetics of formation of diethylene glycol (DEG) (ether bond) which is an important side reaction in preparing polyethylene terephthalate was investigated. The following empirical rate expression is proposed for convenience of engineering applications

It has been found by experiment that n = 0.9; apparent activation energy E = 8.2 kcal/mol. The equation can be used to predict the quantity of DEG formed in the reaction. The influence of the process conditions and reactor types on DEG content in polymer are also discussed.
Untersuchung des phasenzustands von polyblock‐netzpolymeren auf der basis von oligoisoprendihydrazid und epoxidoligomeren
Authors: Lipatov Yuri , Shilov Valeri , Gomza Yuri , Kovernik Grigori , Kochetov Dimitri 
Published: April 2003

AbstractDie aus Trübungspunktmessungen erhaltenen Zustandsdiagramme von Mischungen aus Oligoisoprendihydrazid und 4,4‐Dihydroxydiphenylpropandiglycidylether zeichnen sich durch einen oberen kritischen Mischungspunkt aus. Die Ergebnisse der Röntgenkleinwinkeluntersuchungen zeigen, daß während der Polymerisation eine Mikrophasentrennung der Komponenten vor sich geht. Der Mikrophasentrennungszustand bleibt im Netzpolymeren selbst bei Temperaturen erhalten, die die Homogenisierungstemperatur der Oligomermischung um 150°C überschreiten. Die Stabilität der Mikrophasenstruktur kann durch den Einfluß des dreidimensionalen Netzes chemischer Bindungen zwischen Dien‐ und Epoxidblöcken erklärt werden, was die „zwangsläufige Unverträglichkeit”︁ flexibler und starrer Blöcke verursacht.
Graft‐copolymerization of starch with acrylamide, I
Authors: Varma I. K. , Singh O. P. , Sandle N. K. 
Published: April 2003

AbstractThe graft‐copolymerization of acrylamide onto starch by cerium (IV) initiation has been investigated. The effect of the concentration of initiator, monomer and acid on % graft‐on has been determined. The kinetics of the acrylamide polymerization in absence and presence of starch has been studied. The maximum % graft‐on was obtained with 0.3 N HNO3, 0.005 M ceric ammonium nitrate and 1.0 M monomer concentration at 50°C.
Porous bead aliphatic‐aromatic methacrylate copolymers, I. Effect of polymerization conditions on porous structure formation of methyl methacrylate — di(methacryloyloxymethyl)naphthalene copolymers
Authors: Wójcik Anna B. 
Published: April 2003

AbstractThe influence of inert porogenic mixture and monomer mixture composition and concentration on specific surface areas, pore size distribution, volumes of pores capable of capillary condensation of nitrogen and true density of copolymers were investigated for a new type of methacrylate monomer system: methyl methacrylate and di(methacryloyloxymethyl)naphthalene. The obtained copolymers exhibit similar character as it is typical for PPSPPS = Porous by Precipitant and Solvent.
styrene‐divinylbenzene resins.
Stoichiometry of sulphuric acid sorption by nylon 6
Authors: Ichimura Ayako , Iijima Toshiro , Petropoulos John H. 
Published: April 2003

AbstractSorption of sulphuric acid by Nylon 6 has been investigated. The results have been interpreted by considering the two‐step dissociation of sulphuric acid in aqueous solution. Sorption occurs predominantly in the 2H+ + SO2−4 mode, but the contribution of the H+ + HSO−4 mode becomes considerable at higher concentrations. Standard affinities for both modes have been estimated.
Synthesis and thermal properties of poly(phenoxy trifluoroethoxy phosphazenes)
Authors: Kajiwara M. , Miwa E. , Saito H. 
Published: April 2003

AbstractCopolymers were prepared by the reaction of poly(dichloro phosphazene), phenoxide, and trifluoro ethoxide in THF. Elastic copolymers having lower Tg than that of poly(trifluoroethoxy phosphazene) were formed when the ratio of phenoxide: trifluoro ethoxide was between 0.5:1.5 and 1.5:0.5.