bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solid‐state polycondensation of poly(ethylene terephthalate) films
Authors: Karayannidis George , Sideridou Irini , Zamboulis Demetris , Stalidis George , Bikiaris Demetris , Lazaridis Nicolaos , Wilmes Aloyse 
Published: April 2003

AbstractThe solid‐state polycondensation of poly(ethylene terephthalate) (PET) amorphous and unoriented films from Du Pont (precursor for their Mylar® Du Pont's registered trade mark for the polyester film.
polyester film) prepared from a specified catalyst and monomer system has been studied. The effect of various reaction parameters such as reaction temperature and time on inherent viscosity (ηinh) and number of carboxy and hydroxy end‐groups has been investigated. From ηinh measurements an empirical equation was taken which allows the calculation of (M̄n) of PET film after solid‐state polycondensation at a certain temperature and time. The melting behaviour of the solid‐state polycondensated samples was also studied.
Pervaporation separation of water‐ethanol through modified chitosan membranes, II. Carboxymethyl, carboxyethyl, cyanoethyl, and amidoxime chitosan membranes
Authors: Lee Young Moo , Shin Eun Mi , Noh Si Tae 
Published: April 2003

AbstractThe present study investigates the pervaporation performance of four kinds of modified chitosan membranes to separate water from aqueous ethanol solution. Chitosan was prepared from chitin abstracted from the crab shell and subsequently deacetylated with aqueous NaOH solution. Modified chitosan membranes examined in this study include carboxymethyl chitosan, carboxyethyl chitosan, cyanoethyl chitosan, and amidoxime chitosan. The incorporation of hydrophilic functional groups into the 6‐O position of chitosan enhances the selectivity of modified chitosan membrane compared to the previously reported chitosan‐acetic acid complex membrane. Among the modified chitosan membranes, membranes containing carboxy groups show the best pervaporation performance. Carboxymethyl chitosan membranes show the maximum swelling and ethanol flux at approx. 15 wt.‐% feed ethanol concentration due to the coupling and plasticizing effect.
Cationic polyelectrolytes, XI. Polymers with quaternary N‐atoms in the main chain obtained by condensation polymerization of epichlorohydrin with amines
Authors: Dràan Stela , Ghimici Luminita 
Published: April 2003

AbstractWater soluble cationic polyelectrolytes containing quaternary nitrogen atoms within the main chain were prepared via condensation polymerization of epichlorohydrin (ECH) with dimethylamine (DMA) and N,N‐dialkylaminoalkylamines. The main parameters of the reaction that influence the polymer properties are: DMA/asymmetrical diamine molar ratio, the initial concentration of amine solution, NaOH/amine molar ratio, ECH/amine molar ratio, and asymmetrical diamine structure. The feature of flexible polyelectrolyte own to the investigated polymers was emphasized by the viscosimetric behaviour in dilute aqueous solutions with and without salt presence.
Study of the conduction mechanisms in polycarbonate
Authors: Amin M. , El‐Shekeil A. , Mounir M. , Elez M. Abu 
Published: April 2003

AbstractCurrent‐voltage characteristics of polycarbonate samples (PC) have been studied in the voltage range 50–1000 V. The effect of UV‐irradiation at λ = 225 and 300 nm, and thermal annealing on the electrical conductivity (σ) of PC was studied. The σ vs. 1/T relationship shows two slopes, i.e. two possible conduction mechanisms. The obtained results made it possible to determine a complete set of conduction parameters including activation energy and jump distance.
Porous terpolymers: Poly(acrylonitrile‐co‐vinyl acetate‐co‐divinylbenzene)
Authors: Kolarz Bożena N. , Trochimczuk Andrzej , Wojaczyńska Maria 
Published: April 2003

AbstractTerpolymers of acrylonitrile (AN), vinyl acetate (VA) (7.5–30 mol‐%, related to AN), and divinylbenzene (DVB) (10 wt.‐%) were prepared by suspension polymerization. The diluents used were mixtures of toluene or cyclohexanol (90 vol.‐%) with solvents (10 vol.‐%) such as hexadecane (HD), octane (O), dodecane (D), 2‐ethylhexanol (E) or benzyl alcohol (B).It has been found that AN‐VA‐DVB terpolymers have a higher porosity, about 0.61–0.68, than corresponding AN‐DVB copolymers. The terpolymers obtained with mixtures of various diluents differ in their supermolecular structure although they had similar porosity characteristics.The thermal effects accompanying heating of the terpolymers above 200°C significantly exceed that of nitrile groups cyclization observed of the other AN polymers.
Monothiirane als reaktive Verdünner für Epoxidharze
Authors: Večeřa Miroslav , Milič Richard , Mleziva Josef 
Published: April 2003

AbstractLangkettige aliphatische Monothiirane können als reaktive Verdünner für Epoxidharze benutzt werden. Die Eigenschaften der ausgehärteten Produkte entsprechen denen, die bei der Verwendung von entsprechenden Monooxiranen (Monoglycidylethern oder ‐estern) gewonnen werden. Von Vorteil ist die Beschleunigung des Aushärtungsprozesses mit aliphatischen Polyaminen und Säureanhydriden sowie die geringere Toxizität.
Zur Bestimmung von funktionellen Gruppen in Polymeren mit elektroanalytischen Methoden
Authors: Peter Ralf 
Published: April 2003

AbstractIm Zuge der ionischen Modifizierung von Polymeren bieten sich elektroanalytische Charakterisierungsverfahren an. Die Palette der analytischen Probleme reicht dabei von der Bestimmung saurer oder basischer funktioneller Gruppen bis hin zur Quantifizierung reduzierbarer und oxidierbarer Spezies — und dies teilweise im spurenanalytischen Bereich. Praktisch relevante und theoretisch interessante Beispiele hierfür sind unter anderen die Ermittlung des Hydroxy‐Gruppengehaltes in Ethylen‐Vinylacetat‐Copolymeren und Epoxidharzen sowie die Bestimmung von als Restmonomerem vorliegenden Doppelbindungseinheiten in Acrylsäure‐Styrol‐Polypropylen‐Compounds und in Maleinsäureanhydrid‐Polyolefin‐Pfropfcopolymeren. Es werden konkrete Lösungsvarianten zu den genannten Problemstellungen beschrieben und die entsprechenden Ergebnisse diskutiert.
Synthesis of a thiol‐terminated poly(L‐glutamic acid) by polymerization of N‐carboxyanhydrides on solid supports
Authors: Palacios Paul , Bussat Philippe , Bichon Daniel 
Published: April 2003

AbstractA novel method of synthesizing a thiol‐terminated poly(L‐glutamic acid)IUPAC name: α‐hydro‐ω‐(2‐mercaptoethyl)amino‐poly{sodium imino‐[1‐(2‐carboxylatoethyl)‐2‐oxo]ethylene}.
(PLGA) is reported. Synthesis of this compound is accomplished with the aid of a solid phase support. The procedure consists of first preparing aminoethyl disulfide‐functionalized silica, glass or polystyrene solid supports. The support thus prepared is then reacted with ester‐protected γ‐benzyl‐L‐glutamate or γ‐piperonyl‐L‐glutamate N‐carboxyanhydride (NCA) to obtain the conjugated poly(γ‐ester‐L‐glutamate)‐support. Then the protected ester group is acidolyzed by adding hydrobromic acid or trifluoroacetic acid (TFA). Finally, the disulfide bond of the resulting acid is cloven by reacting it with mercaptoethanol thus producing the desired end product, the thiol‐terminated poly(L‐glutamic acid) (yield 64%).
Preparation and properties of poly(p‐nitrophenylquinoxaline‐imide‐amide)s
Authors: Bruma M. , Sava I. , Hamciuc E. , Belomoina N. M. , Krongauz E. S. 
Published: April 2003

AbstractNew thermostable polymers containing p‐nitrophenyl substituted quinoxaline units and imide rings as well as flexible amide groups have been synthesized by polycondensation reaction of a diaminoquinoxaline derivative carrying p‐nitrophenyl substituents with diacid dichlorides incorporating preformed imide cycles. These polymers show better solubility compared to related products which do not contain nitro groups. They have also a high thermal stability and good electrical insulating properties.
Light‐induced polymer and polymerization reactions, 48. Photo‐induced reactions in novolac resins containing onium salt photoinitiator systems
Authors: Timpe Hans‐Joachim , Rautschek Holger 
Published: April 2003

AbstractThe exposure of photoinitiators contained in novolac layers, which give protonic or Lewis acids by irradiation, leads to the degradation of these resins. Benzylic carbocations are formed as intermediates, which can be detected by their long wavelength absorptions between 525 and 545 nm. These intermediates react either with nucleophiles (e.g. anions, water) to benzyl derivatives, or with phenols to novolacs (back reaction), or they yield, under abstraction of protons, ortho‐quinone methides, also coloured (absorption maxima at ∼400 nm). Altogether, a complicated system of competitive reactions occurs and, therefore, kinetic calculations are very difficult. Due to changes caused in solubility, this photoinduced degradation of novolacs can be used for photolithographic purposes. But problems arise in negative working resists using novolac resins as polymeric binders.
Synthesis and characterization of polymers containing naphthyl‐2H‐benzotriazoles, 1. Monomer synthesis and characterization
Authors: Shuhaibar K. F. , Rasoul F. A. , Pasch H. , Mobasher A. 
Published: April 2003

Abstract2‐(2‐Hydroxynaphthyl)‐2H‐benzotriazoles were synthesized by azo coupling of o‐nitrobenzene diazonium chloride with 2,3‐, 2,5‐, and 2,7‐dihydroxynaphthalenes, respectively, followed by reductive cyclization with zinc powder and sodium hydroxide. The mode of coupling reactions has been elucidated using NMR spectroscopy and showed that the coupling occurred at the α‐position of the dihydroxynaphthalenes. The treatment of 2‐(2,7‐dihydroxynaphthyl)‐2H‐benzotriazole with acryloyl or methacryloyl chloride, respectively, gave the corresponding (meth)acryloyloxynaphthyl‐2H‐benzotriazoles, which, along with their methoxy and chloro derivatives, provide a new class of polymerizable UV absorbers.
Oberflächenstrukturierung polymerer Fasern durch UV‐Laserbestrahlung. 12. Pulszahlabhängige phänomenologische Untersuchungen zur UV‐laser‐induzierten Oberflächenstruktur von Poly(ethylenterephthalat)‐Fasern,
Authors: Kesting Wolfgang , Schollmeyer Eckhard 
Published: April 2003

AbstractDurch die Bestrahlung von verstreckten Poly(ethylenterephthalat)(PETP)‐Fasern mit einem gepulsten UV‐Excimer‐Laser entstehen charakteristische Strukturierungen auf der Faseroberfläche. In einem Experiment, bei dem PETP‐Fasern unter einem Mikroskop bestrahlt werden, wird die Änderung der Oberflächenstrukturierung pulszahlabhängig untersucht. Diese Untersuchungen werden für verschiedene Pulsenergiedichten, Wellenlängen und unterschiedliche Verstreckungen der Faser durchgeführt. Mit zunehmender Anzahl von Laserpulsen kommt es zu einer gröberen Ausbildung der Strukturierung, in der feiner ausgeprägte Strukturen verschwinden. Nach einer ausreichenden Anzahl von Laserpulsen zerfällt die Faser in ellipsenförmige Segmente. Quantitative Untersuchungen ergeben eine logarithmische Abhängigkeit zwischen dem mittleren Abstand der Aufwerfungen und der Anzahl der angewandten Laserpulse.
Modifikation von Harnstoff‐Formaldehyd‐Schäumen mit einem Stärkehydrolysat
Authors: Braun Dietrich , Rösinger Sabine , Unvericht Reinhard 
Published: April 2003

AbstractDer Einsatz eines hauptsächtlich aus Glucose, Maltose und Maltotriose bestehenden Stärkehydrolysates bei der Herstellung von UF‐Schaumstoffen führt zu einer sichtbaren Verminderung von Partikelagglomerationen ohne eine Verschlechterung der Morphologie und damit der mechanischen Eigenschaften. Dadurch kann die begrenzte Lagerstabilität der bei niedrigem Formaldehyd/Harnstoff‐Verhältnis produzierten Harze verbessert werden. Dagegen ist es nicht möglich, den Gehalt an freiem oder acetalisch gebundenem Formaldehyd im Vorkondensat durch solche Zusätze zu erniedrigen.
Properties of cationically polymerized aromatic monomers which are present in C9 resinfeed. Properties influencing printing ink compositions
Authors: Salemis Philippe , van Eikenhorst Rita 
Published: April 2003

AbstractThe main components of the “C9 cut”, a by‐product from steam cracking of gasoil or naphtha, have been cationically homopolymerized. The properties of the resulting homopolymers have been related to their structure. As some of the main application areas of the C9 resins are printing ink resins and adhesives, we focused primarily on these fields of application when considering the properties of these homopolymers.
Functionalization of dextran: Incorporation of carboxy groups by O‐succinoylation
Authors: Arranz F. , Sanchez‐Chaves M. , Ramirez J. C. 
Published: April 2003

AbstractThe modification reaction of dextran with succinic anhydride using pyridine as catalyst and N,N‐dimethylformamide/lithiumchloride system as solvent was studied. The structure of the resulting polymers was determined by means of 1H and 13C NMR spectroscopy. A linear dependence of the reaction rate on succinic anhydride concentration was found. The orders with respect to pyridine and polymer concentrations were 1 and 2, respectively. The activation energy was found to be 69.0 kJ/mol. 13C NMR spectra at 75.4 MHz of partially modified dextran with monosuccinate groups were studied in order to evaluate the selectivity of the reaction of dextran with succinic anhydride in the homogeneous phase. Analysis of the spectra of ring carbons in the anhydroglucose units shows that the reactivity of individual hydroxy groups decreases in the order C‐2 ∽ C‐3 > C‐4. For samples with higher degree of substitution the order is C‐4 > C‐3 > C‐2. The results were explained by considering the formation of intramolecular hydrogen bonds as well as by steric considerations.
Struktur und eigenschaften von simultanvernetzten bismaleimidmodifizierten novolak‐epoxidharzen
Authors: Lüders Günter , Goering Harald , Pohl Martina , Raubach Heinz 
Published: April 2003

AbstractN,N′‐4,4′‐Diphenylmethan‐bismaleimid (BMI) wurde in halbfesten Phenolnovolak‐Epoxidharzen (EP) bis P̄, = 10 oligomerisiert. Die novolakgehärteten EP‐BMI‐Festharze bilden eine Zweiphasenstruktur, bestehend aus einer EP‐BMI‐Mischphase der beiden sich durchdringenden Netzwerke (interpenetrating polymer network, IPN) und einer BMI‐Phase. Die dynamisch‐mechanischen Eigenschaften hängen vom Gesamt‐BMI‐Anteil w2 und vom Oligomerisierungsgrad P̄n des BMI ab. Der relative Schubmodul des EP‐BMI‐Harzes im kautschukelastischen Zustand zeigt, daß beide Phasen kohärent sein können. Die Glastemperatur Tg korreliert mit dem Oligomerisierungsgrad, z. B. entspricht ΔPn ≡ 10 einem ΔTg ≡ 35 K und einem BMI‐Anteil Δ wx2 ≡ 0,25 in der Mischphase. Die Bruchzahigkeit bleibt unerwartet konstant.
Effects of composition and plastifier on the light scattering of polymer glasses and properties of polymeric optical fibers made from styrene‐methyl methacrylate copolymers
Authors: Dvořánek Ladislav , Koňák Čestmír , Neuhäusl Tomáš , Machová Lud'ka , Šorm Miloslav 
Published: April 2003

AbstractHigh optical purity polystyrene (PS), poly(methyl methacrylate) (PMMA) and styrene‐methyl methacrylate statistical copolymers (S‐MMA) were prepared. Light scattering measured on polymeric glasses depends on the chemical composition of the polymer and on the refractive index of the plastifier added. An isorefractive plastifier reduces considerably the scattering values for the copolymers S‐MMA, while having no significant effect on the scattering of PMMA. A plastifier with a refractive index different from that of the polymer raises distinctly the light scattering values in all cases. It has been shown that the isorefractive plastifier has a favourable effect on attenuation loss of polymeric optical fibers (POF) obtained from the copolymer S‐MMA 2/1.
Thermostable polyesters containing imide and phenylquinoxaline units
Authors: Bruma M. , Sava I. , Hamciuc E. , Hamciuc C. , Belomoina N. M. , Krongauz E. S. 
Published: April 2003

AbstractThermostable, heterocyclic polyesters containing imide and phenylquinoxaline units have been synthesized by solution polycondensation of bis(hydroxyphenylquinoxaline) derivatives with diacid dichlorides containing preformed imide rings or by the reaction of bis(aminophenylquinoxaline) derivatives with dianhydrides containing ester groups. The thermal stability of these compounds is discussed and compared with related heterocyclic polymers. Electrical properties of the polycondensates were also studied.
On the effect of water on the durability of PP and PC/acrylic adhesive joints
Authors: Di Ruocco V. , Morra M. , Occhiello E. , Garbassi F. 
Published: April 2003

AbstractThe stability of PP and PC/acrylic adhesive joints has been assessed using a thermodynamic method based on surface tension components.Surface characterization showed that plasma treatment induces the formation of an oxygen‐rich layer on treated surfaces. In the case of PP this layer does not change its composition upon immersion in water, while for PC leaching of oxidized species with low molecular weight was observed.Both untreated and plasma treated PP joints showed reasonable stability against immersion in water. A small reduction of shear strength was observed, but the fracture remained adhesive for untreated PP and cohesive for plasma treated PP.In the case of PC, only joints made from untreated PC showed fair sensitivity against immersion in water, while those made from plasma treated specimens degraded dramatically. In the latter case the locus of failure moved to the adhesive/adherend interface, the presence of a very hydrophilic, low molecular weight layer being suggested as responsible for this behavior.
Antioxidants and stabilizers, 116 Influence of the carbon black chezacarb EC on polyolefin thermooxidation: A model study with cyclohexene doped with chain‐breaking antioxidants
Authors: Rotschová Jitka , Pospíšil Jan 
Published: April 2003

AbstractThe ageing of polyolefins is accelerated by carbon black Chezacarb EC used as a filler. Conditions for selection of suitable chain‐breaking antioxidants protecting against degradation were simulated using cyclohexene doped with various amounts of carbon black and oxidized at 60°C. The results obtained reveal an acceleration of cyclohexene oxidation in the phase following the induction period (IP). The oxidation acceleration is similar to the effect caused by powdered copper(0) or copper(II) ions. Polynuclear phenolic antioxidants are able to stabilize cyclohexene for periods longer than 120 h only in the presence of low amounts of Chezacarb (up to 0.5 wt.‐%). At higher Chezacarb concentrations, merely a prolongation of IP may be achieved. Arylene diamines are efficient stabilizers only if combined with a high concentration of Chezacarb (10 wt.‐%). None of the chain‐breaking antioxidants used was able to diminish the oxidation rate of cyclohexene in the phase after IP.
Synthesis, characterization, and glass‐reinforcement of poly(oxysilane imide)s
Authors: Patel Hasmukh S. , Vyas Hemant S. 
Published: April 2003

AbstractPoly(oxysilane imide)s were prepared via Diels‐Alder (DA) intermolecular polymerization of bis(2‐furylmethyloxy)‐dimethyl silane (1) with different bis(maleimido)‐compounds (2a–h). The DA reaction was carried out in tetrahydrofuran as solvent as well as in bulk followed by dehydration (aromatization) of poly(tetrahydrophthalimido)‐intermidiates (3a–h) in the presence of acetic anhydride. All poly(oxysilane imide)s (4a–h) were characterized by elemental analyses, IR spectral studies, and thermogravimetry. 1 and 2 were polymerized (at 130 ± 10°C) by in‐situ Diels‐Alder intermolecular reaction into poly(oxysilane imide)s‐glass fibre composites (i.e. laminates) without evolution of by‐products. The prepared composites were characterized by chemical resistivity and mechanical properties.
Correlation between microscopic structural parameters and macroscopic flow behaviour of some polymer‐surfactant systems suitable for tertiary oil recovery
Authors: Aust Nicolai , Meyer‐Kolshorn Uwe , Schreiber Axel , Zugenmaier Peter 
Published: April 2003

AbstractSome materials, suitable for application in polymer‐surfactant flooding used in tertiary oil recovery (EOR), have been characterized by static and dynamic light scattering and studied in respect to their suitability in various model brines by measuring their rheological and dynamic‐rheological behaviour. Xanthan and polyacrylamides of different degree of hydrolysis have been used as polymers, an ethylene glycol sulfonate as surfactant.Correlations have been established between microscopic structural parameters (Hydrodynamic radius, radius of gyration, molar mass, shape of the polymers) and the macroscopic behaviour, such as viscosity and elasticity, being important rheological parameters for EOR application. Additional investigations on surface tension and long term viscosity study lead then to a judgement for the efficiency and long term stability of polymer‐surfactant slugs in various reservoirs of different salinity.
Functional polyamides. 3. Synthesis and chelating properties of a new poly(amide thioether)
Authors: Yagci Yusuf , Denizligil Selcuk , Bicak Niyazi , Atay Tulay 
Published: April 2003

AbstractPolymerization of β,β′‐(ethylenedithio)dipropionitrileIUPAC name: 4,7‐dithiadecane dinitrile.
with formaldehyde in the presence of sulfuric acid was carried out in order to permit the synthesis of polymides containing thioether groups. The obtained poly(amide thioether)s were characterized; they coordinate mercury (II) with a high degree of selectivity.
Synthesis and characterization of bifunctional cellulose‐g‐poly(glycidyl methacrylate) based cation exchangers containing both sulfonic and carboxylic acid groups
Authors: Abo‐Shosha M. H. 
Published: April 2003

AbstractCellulose‐g‐poly(glycidyl methacrylate) copolymer was reacted with aqueous solutions containing mixtures of both sodium sulfite and citric acid, in order to synthesize bifunctional cation exchangers containing both sulfonic and carboxylic acid groups. Factors affecting the reaction, such as percent neutralization of citric acid with sodium carbonate, time, temperature, liquor ratio, reagents‐to‐epoxide molar ratio, and monosodium salt of citric acid‐to‐epoxide molar ratio were studied. Reaction conditions were selected to prepare five kinds of cation exchangers of different sulfonic and carboxy contents. These exchangers were characterized by potentiometric titrations, durability tests, and water solubility.
Preparation of prepolymers from diglycidylether of bisphenol A containing imide groups
Authors: Cádiz Virginia , Mantecón Ana , Serra Angels , Thepaut Christophe 
Published: April 2003

AbstractEpoxy resins derived from Bisphenol A have been modified with new diphenols containing imide moieties in order to improve their thermal properties. The diphenols have been synthesized from dianhydrides and aminophenols by condensation reactions. Diphenols as well as modified resins have been characterized by IR and NMR spectroscopy. The thermal characteristics were evaluated by DSC and TGA.
Chromatographic properties of macroporous beads from poly(GMA‐co‐EDMA)
Authors: Horák D. , S̆vec F. , Tennikova T. B. , Náhånek M. 
Published: April 2003

AbstractA series of macroporous glycidyl methacrylate‐ethylene dimethacrylate copolymers have been prepared by the suspension polymerization according to a statistical design of experimental approach in which concentration of ethylene dimethacrylate and time needed for raising the polymerization temperature from 20 to 70°C have been varied. The porous properties of hydrolyzed copolymers have been characterized by means of size exclusion chromatography using polystyrene standards in tetrahydrofuran. Pore volume, specific surface area, and pore size are affected by the crosslinking agent concentration rather than by the rate of temperature increase during the polymerization reaction.