bluuebunny/crossref_metadata_2025_split huggingface dataset:
Macromolecular structure of coals. V. Molecular weight distribution of extracted coal chains
Authors: Hill‐Lievense Mary Elizabeth , Lucht Lucy M. , Peppas Nikolaos A. 
Published: April 2003

AbstractSeven coal samples with carbon contents ranging from 69.95% to 94.17% on a dry mineral matter‐free (dmmf) basis were extracted with pyridine at reflux temperature for two weeks. The liquids obtained (coal extracts) were analyzed for molecular weight distribution by gel permeation chromatography at 35°C using a solution of 10% pyridine and 90% tetrahydrofuran as the mobile phase. Calibration was done by use of anionically‐prepared monodisperse polystyrene and by a series of polynuclear low molecular weight compounds. The number average (M̄Mn) and weight average (M̄w) molecular weights of the coal extracts were found to depend on the carbon content of the initial coal samples. As the carbon content increased, M̄n and M̄w decreased from original values of 640 and 1120 for the lignite sample, passing through a minimum of 600 and 895 respectively and reaching a maximum of M̄n = 725 and M̄w = 1 445 for the anthracite sample with 94.17% C. Previously extracted coal matrices were alkylated by the Sternberg alkylation technique which causes degradation of the macromolecular chains of the coal matrix. Gel permeation chromatographic analysis of pyridine‐extracted liquids of the solid alkylated coal showed average molecular weights smaller than those of the original coal extracts (M̄n = 440–470, M̄w = 445–590).
Immobilisierung von corynebacterium simplex durch einschluß in synthetische vernetzte gele — Biokatalysatoren für die steroidumwandlung
Authors: Manecke Georg , Klussmann Udo 
Published: April 2003

AbstractGanze, lebensfähige Zellen von Corynebacter. simplex wurden in ein wasserlösliches Poly[acrolein‐co‐(1‐vinyl‐2‐pyrrolidon)] durch Vernetzung eingeschlossen. Als Vernetzer wurden verschiedene Alkylendioxydiamine und Oxaalkylendioxydiamine synthetisiert. Die Polymer‐Zell‐Konjugate zeigten eine Steroid‐Δ1‐dehydrogenase‐Aktivität, und die Bildung von Prednisolon aus Hydrocortison wurde untersucht. Die Aktivität war abhängig von der Hydrophobie des einschließenden Gels und konnte durch eine Enzyminduktion und eine Behandlung mit einer Pepton‐enthaltenden Nährlösung auf ungefähr das Zehnfache gesteigert werden. Vorteilhafterweise konnte die Steroidumwandlung mit einem Überschuß an mikrokristallinem Hydrocortison durchgeführt werden. In diesem Fall wurden 0.57 g Prednisolon pro Tag und pro g Biokatalysator erhalten.
Vinyl polymerization by carbon black, VI. Physico‐chemical characteristics of poly(N‐vinylcarbazole) prepared by modified and unmodified carbon black
Authors: Biswas Mukul , Haque Shah A. , Basu Sakti P. 
Published: April 2003

AbstractThe polymerization initiating activity of carbon black N220, unmodified as well as modified by pretreatment with various protonic and aprotonic acids has been examined in regards to N‐vinylcarbazole polymerization. The physico‐chemical characteristics of the polymer obtained by these catalyst systems have been investigated by I.R., X‐ray, 1H‐NMR, 13C‐NMR, gel permeation chromatography and thermal analysis measurements. Under certain conditions the resultant polymer shows some partial insolubility in methylethylketone. Contrary to the usual belief, this is not due to any stereochemical difference between the polymeric entities as observed by 13C‐NMR spectrum analysis of the methylethylketone insoluble fraction of the polymer.
Synthesis and characterization of some 2,4′‐dibenzyldiisocyanate ionic polymers
Authors: Buruianǎ Tinca , Beştiuc Ioan , Popescu Valeriu , Caraculacu Adrian 
Published: April 2003

AbstractCationic polyurethanes were synthesized by a two step Menschutkin reaction. A prepolymer with tertiary dimethylamino end groups and a dihalide (1,3‐dimethyl‐4,6‐di(chloromethyl) benzene) were used in the first step, and 1,8‐diaza bicyclooctane in the second step. The polymers from flexible and transparent films and their solutions give ionomer dispersions by adding of acetone. The viscometric behaviour of diluted solutions was studied in solvents with different dielectrical constants.
The effect of mixing polymers on their combustion
Authors: Elomaa Matti A. , Salo Simo , Lindberg J. Johan 
Published: April 2003

AbstractPyrolysis and burning experiments were carried out with polypropylene, polystyrene and mixtures of them with cellulose. Polycyclic aromatic hydrocarbons (PAH) were extracted from the soot formed, and the extracts were examined by gas chromatography. The gas chromatograms were compared, like fingerprints, using a computer program developed for this purpose. The amount of benzo(a)pyrene was determined. The pyrolysis of the mixtures was also followed up by thermogravimetry. Under the experimental conditions the mixing of cellulose with hydrocarbon polymers (1:1 w/w) had only a small effect on the products formed during pyrolysis and combustion as compared with the treatment of the corresponding pure compounds.
Effect of copolymers modifying PVC on its physical and mechanical properties and its UV‐radiation resistance. 4. Photodehydrochlorination of PVC in films containing MMA/MA, VC/VAC, MBS or ABS
Authors: Kamińska A. , Kaczmarek H. 
Published: April 2003

AbstractThe process of PVC dehydrochlorination caused by 253.7 nm UV‐radiation in PVC films and its blends with 1% of copolymers MMA/MA, VC/VAC, MBS or ABS has been investigated. The analyses of UV‐VIS spectra pointed out that the increase of concentration of polyene structures, being created as a result of PVC photodehydrochlorination, is smaller in films containing the copolymers than that in films made of pure PVC. It suggests that the presence of 1% of these copolymers in PVC films evidently restrains photodehydrochlorination of this polymer. These copolymers used as modyfiers which help processing of PVC or improve its impact resistance can additionally act as PVC photostabilizers restraining photodehydrochlorination.
Quantitative bestimmung der verteilung von additiven in kunststoffen mit hilfe der neutronenaktivierung und autoradiographie. Grundlagen der untersuchungsmethode
Authors: Krassowski Georg 
Published: April 2003

AbstractDie quantitative Bestimmung der Verteilung von Additiven in Kunststoffen bereitet in der Kunststofftechnologie derzeit noch Schwierigkeiten, da mit den gebräuchlichen Beurteilungsmethoden häufig nur grobe Klassifizierungen vorgenommen werden können. Mit Hilfe der Neutronenaktivierung von Additiven und der Autoradiographie als registrierendem Verfahren lassen sich dagegen praxisgerechte Mischgrade sehr nachweis‐ und auflösungsempfindlich quantitativ bestimmen. Die Einflußfaktoren dieser Untersuchungsmethode werden systematisch in Form von Gleichungen zusammengestellt und auf die praktische Anwendung übertragen.
Biocide polymers, 14. Modification of polyvinyl alcohol with biologically active N‐phosphorylated 3‐amino‐1,2,4‐triazoles
Authors: Hartmann Manfred , Bauer Hans‐Jürgen , Wermann Kurt 
Published: April 2003

AbstractN‐Phosphorylated 3‐amino‐1,2,4‐triazoles, prepared from the herbicide amitrole by acylation with phenyl‐ and 4‐nitrophenyl phosphorodichloridate, respectively, as well as with phosphoryl chloride were reversibly linked to poly(vinyl alcohol) designed for controlled release of the active agent.4‐N,N′‐Dimethylaminopyridine was used as catalyst for the polymeranalogous esterification reactions. IR, 1H‐NMR, and 31P‐NMR analyses of polymers suggest attachment of the herbicide moiety as pendant groups bound via phosphate groups at the ring nitrogen. Comparative hydrolysis studies demonstrated the influence of the substitution degree of PVAL and of the modification of the phosphorus‐to‐triazolide linkage upon the hydrolytic release of amitrole.
Graft copolymers of starch and polyacrylonitrile. 1. Effect of source
Authors: Patel A. R. , Patel K. C. , Patel R. D. 
Published: April 2003

AbstractGraft copolymers of six cereal starches with polyacrylonitrile have been prepared and investigated. The molecular weights, the frequencies of grafting and the absorbencies of the saponified products are almost independent of the source of granular starches. The percent yield and percent add‐on of graft copolymers from gelatinized starches are almost the same as those from granular cereal starches. However, their molecular weights, corresponding frequency of gelatinized starch graft copolymers have increased five times, while absorbency is doubled. The effects of initiator monomer concentration, and of dilution are discussed.
Synthesis of porous styrene divinylbenzene copolymers
Authors: Poinescu Ignat , Popescu Vespasian , Carpov Adrian 
Published: April 2003

AbstractThe copolymerization of styrene with divinylbenzene in the presence of tri‐n‐butylphosphate or a mixture of di‐2‐ethylhexylphosphoric acid and chlorobenzene was studied in order to perform porous networks, solvent impregnated copolymers, etc. The diluents behave as strong precipitants allowing to prepare permanent porous copolymers having low contents of the crosslinking agent.The effects of dilution, crosslinking degree, and nature of diluent on the porosity as well as on the uptake coefficients, the specific surface area, and the average pore diameter, were studied to elucidate the manner in which such inert compounds contribute to the formation of porous networks.
Polymérisation induite sous irradiation laser visible. 2. Sensibilisation par les colorants
Authors: Chesneau E. , Fouassier J. P. 
Published: April 2003

AbstractDe nombreux sensibilisateurs et amorceurs ont été testés pour la polymérisation d'un acrylate, sous irradiation visible. Les rôles de chaque constituant du système, des concentrations et des conditions d'irradiation (puissance du faisceau et focalisation) sont reportés. Les meilleurs résultats sont obtenus avec l'éosine, l'amorceur étant PDO + MDEA. La réactivité de ce système est comparée à celle des amorceurs UV pour la polymérisation en film et en solution. Les processus mis en jeu sont discutés.
The effect of molecular orientation on the vapour sorption of cyclohexane in amorphous polyester fibres
Authors: Czerwiński Wojciech 
Published: April 2003

AbstractThe sorption and transport of cyclohexane in poly(ethylene terephthalate) (PETP) fibres with various molecular orientations below the glass transition have been studied. The results have been analyzed in terms of the dual sorption model which has been successfully employed for glassy polymers. It has been shown that the capacity of the Langmuir mode of sorption inherent to glassy polymers is connected with the molecular orientation in the fibres of PETP. The increase of molecular orientation in the fibres has caused the decrease of the Langmuir capacity of PETP. This postulates a decrease in the free volume as a consequence of gradually increasing molecular orientation. Observations on the diffusion coefficients and activation energies for cyclohexane‐PETP fibres system have been discussed.
Versuche zur stufenweisen epoxid/methacrylat‐photopolymerisation mit diaryliodoniumsalz‐photoinitiatoren
Authors: Klemm Elisabeth , Flammersheim Hans‐Jürgen , Märtin Rolf , Hörhold Hans‐Heinrich 
Published: April 2003

AbstractDSC‐Untersuchungen bestätigen das präparative Ergebnis, wonach eine selektive, zeitlich aufeinanderfolgende Photopolymerisation von Methylmethacrylat und Phenylglycidether aus einer Mischung beider Monomeren möglich ist mit Diaryliodoniumtetrafluorborat/Benzoinmethylether als Photoinitiator. Die Trennung beider Polymerisationsprozesse ist abhängig von der Bestrahlungsintensität und von der Zusammensetzung der Monomermischung. Aus einer Monomermischung (80 Gew.‐% Methylmethacrylat [MMA]/20 Gew.‐% Phenylglycidether [PGE]) polymerisiert bei einer Bestrahlungsintensität von I = 0,7 mJ/s cm2 bis zum Eintreten des Geleffektes nur MMA (etwa 30 Minuten). Die Epoxidpolymerisation kann danach mit dem ungefilterten Licht einer Quecksilberhochdrucklampe innerhalb von 10 Minuten durchgeführt werden. Die zeitliche Trennung beider Prozesse gelingt nur, wenn MMA Hauptbestandteil der Monomermischung ist.
Interaction of copoly(L‐lysine · HBr γ‐methyl‐L‐glutamate)s with 2‐(4′‐hydroxyphenylazo) benzoic acid
Authors: Kuramoto Noriyuki , Aoyama Tomoyuki , Yamaguchi Mieko , Nagai Katsutoshi , Hayama Shigeru 
Published: April 2003

AbstractCopoly(Nε‐benzyloxycarbonyl(Cbz)‐L‐lysine γ‐methyl‐L‐glutamate)s of different amino acid composition were obtained from the mixture of N‐carboxy anhydride (NCA) of Nε‐Cbz‐L‐lysine and NCA of γ‐methyl‐L‐glutamate of different molar ratio. Interactions of copoly(L‐lysine · HBr γ‐methyl‐L‐glutamate)s with 2‐(4′‐hydroxyphenylazo) benzoic acid were evaluated by means of difference visible absorption spectroscopic measurement using the Benesi‐Hildebrand equation. With an increase in residue mole of L‐lysine in the copolymers, the binding constants per residue mole of L‐lysine in the copolymers were reduced.
Water‐insoluble polyacrylamides, IV. Polychelates based on poly(o‐N‐acryloyl amino benzoic acid)
Authors: Patel Kishore , Suthar Bhikhu 
Published: April 2003

AbstractPolychelates of Fe(II), Co(II), Ni(II), Cr(III) UO2(II), and Zn(II) were prepared from poly(o‐N‐acryloyl amino benzoic acid). All these polychelates are intensely coloured and insoluble in all common organic solvents. They are characterized by electronic reflectance spectra, magnetic susceptibility measurements, elemental analyses, and infrared spectral studies. All the polychelates show six coordinated structure and suggest the octahedral geometry. Conductometric studies indicate these polychelates as non‐electrolytes. From thermogravimetric analyses, the thermal stability of all these polychelates was determined.
Gemeinsame kondensation von harnstoff, melamin und formaldehyd. I. Einfluß der reaktionsparameter
Authors: Braun Dietrich , Abrão Maria de Lourdes , Ritzert Hans‐Josef 
Published: April 2003

AbstractDie Abhängigkeit der gemeinsamen Kondensation von Harnstoff, Melamin und Formaldehyd von den Reaktionsparametern wurde mit Hilfe chromatographischer und spektroskopischer Methoden untersucht. Dabei zeigte sich, daß bei Erniedrigung des pH‐Werts die Reaktivität sowohl von Melamin als auch von Harnstoff gegenüber Formaldehyd ansteigt. Eine kontrollierbare Reaktion von Harnstoff, Melamin und Formaldehyd ist nur im neutralen und alkalischen Medium möglich. Bei Erhöhung des Anteils an Harnstoff im Reaktionsgemisch steigt der Kondensationsgrad an.Ein Vergleich der Mischharze mit den entsprechenden Harnstoff‐Formaldehyd‐und Melamin‐Formaldehyd‐Harzen mit Hilfe chromatographischer und spektroskopischer Methoden ergab Hinweise auf die Bildung von Cokondensaten aus Harnstoff und Melamin. Zum selben Befund gelangt man beim Vergleich der Acetonverträglichkeiten und der Trübungspunkte der Dreikomponentenkondensate mit den reinen Harnstoff‐ und Melaminharzen.
Bestimmung von phenyl‐, alkylphenyl‐ und benzoyl‐endgruppen in bisphenol‐a/polycarbonaten
Authors: Horbach A. , Freitag D. , Müller H. 
Published: April 2003

AbstractFür unter Verwendung von Kettenabbrechern hergestellte Polycarbonate auf Basis von Bisphenol‐A wird ein neues Analysenverfahren zur Bestimmung des Gehaltes an Phenyl‐ und 4‐tert‐Butylphenyl‐Endgruppen vorgestellt, das zusätzlich auch zur Analyse von 4‐Kresyl‐, 4‐Isooctyl‐ und 4‐Cyclohexylphenyl‐ sowie von Benzoyl‐Endgruppen geeignet ist.Das Polycarbonat wird in üblicher Weise durch alkalische Totalhydrolyse in die Grundbausteine abgebaut. In der sauer gestellten Hydrolyselösung werden anschließend die aus den Endgruppen gebildeten Mengen an Phenol, 4‐tert‐Butylphenol, 4‐Kresol, 4‐Isooctylphenol, 4‐Cyclohexylphenol bzw. an Benzoesäure über Reversed‐Phase‐Hochdruckflüssigkeitschromatographie bestimmt. Im Gegensatz zu den literaturbekannten Verfahren zur Analyse von Phenyl‐ und 4‐tert‐Butylphenyl‐Endgruppen kann auf spezielle Anreicherungs‐ bzw. Abtrennungsschritte verzichtet werden.Bei guter Reproduzierbarkeit und Richtigkeit der Ergebnisse zeichnet sich das neue Verfahren durch einen relativ geringen Arbeits‐ und Zeitaufwand aus.
Untersuchung der reaktionen von alkydharzen mit melaminvernetzern
Authors: Pohl Horand Uwe , Traenckner Hans‐Joachim 
Published: April 2003

AbstractBei der anwendungstechnischen und analytischen Untersuchung der Vernetzungsreaktionen von Alkyd‐ mit Melaminharzen sind Effekte zu beobachten, die nicht mit den bekannten Reaktionen zu erklären sind:

Die filmmechanischen Eigenschaften (Pendelhärte, Eindringtiefe, Dehnung) erreichen bei der 130°C‐Einbrennung bereits nach ca. 5 min ihr endgültiges Niveau, die Filmbeständigkeitseigenschaften (Xyloltest, MEK‐Wischtest) dagegen erst nach ca. 30 min.
Die Abhängigkeit des Quellgrades von der Einbrenndauer geht durch ein Minimum.
Die Abhängigkeit der OH‐Menge von der Einbrenndauer geht durch ein Minimum.
Im Abgas wird weniger iso‐Butanol wiedergefunden, als nach den IR‐Ergebnissen aus dem Melaminharz abgespalten wird.
Alle diese Effekte lassen sich durch eine Solvolyse der Alkydestergruppen durch das aus dem Melaminharz abgespaltene iso‐Butanol erklären.
Flameproofing of cellulose and several synthetic polymers by substituted N‐[(phosphinyl) methyl]‐2‐imidazolidinones
Authors: Mikroyannidis John A. 
Published: April 2003

AbstractSubstituted 1‐[(phosphinyl)methyl]‐2‐imidazolidinones were used for development of a novel finishing process referring cotton fabric fire and crease resistant. The process involves treatment of cotton fabric with an acidic solution of substituted 1‐[(phosphinyl)methyl]‐3‐hydroxymethyl‐2‐imidazolidinones and tris (N‐hydroxymethyl) melamine followed by curing. The fire resistance, the crease resistance, and the mechanical strength of the treated fabric were determined in order to evaluate the process. Particularly, the fire resistance of the specimens was determined by measuring their char length, the afterflame time, and the afterglow time. All treated specimens were selfextinguishing. The crease resistance and the mechanical strength of the specimens were determined by measuring their recovery angle and breaking load, respectively. In addition, substituted 1,3‐bis[(phosphinyl)methyl]‐2‐imidazolidinones were used as fire retardant additives in several synthetic polymers such as nylon 66 and polyethylene with significant increase of their limiting oxygen index (LOI) value.
Curing of new trimellitimide glycidyl ester derivatives with aromatic diamines
Authors: Martínez Pedro‐Alberto , Cádiz Virginia , Serra Angels , Mantecón Ana 
Published: April 2003

AbstractThe cure behaviour of new epoxy resins containing a preformed imide ring with m‐phenylenediamine (mPDA) and diaminodiphenylmethane (DDM) was investigated. The progress of polymerization was followed by recording IR and 13C‐NMR spectra at time intervals. The curing proceeded mainly by chain extension at low temperatures, the reaction being not very fast, whereas crosslinking occurred as the gel point was reached (about 15 h at 60°C) by reaction of secondary amino groups with epoxides. Impurities influence, playing the part of catalysts, could be determined from the reaction rate of glycidyl and amino groups. So a kinetic study was made. The thermal behaviour of these cured epoxy resins was also studied.
Evaluation of the glass transition temperature of polymers
Authors: Patel K. C. , Patel R. D. 
Published: April 2003

AbstractAn attempt has been made to determine the glass transition temperatures, Tg, of two series of polymers ((a) polymethacrylates and (b) amylose esters) from the chemical structure of the repeating unit applying the contribution of each element as well as the molecular interaction. A fairly good agreement has been achieved between the theoretical and experimentally reported values of Tg involving the error ranging from 0.5 to 7%.
Adjustment and control of weathering conditions in accelerated tests of polymer materials for better correlation
Authors: Kockott Dieter 
Published: April 2003

AbstractThe principal possibilities of acceleration will be discussed. Technical polymers are a complicated system of several components exposed to the various influencing factors of the weather which themselves are often in interaction. A decisive technical presupposition concerning the comparison of accelerated weathering and outdoor weathering as well as reproducibility of accelerated weathering results are adjustment, measurement and control of the most important influencing parameters in the weathering device. This will particularly be discussed for the following parameters: Spectral energy distribution, irradiance/radiant exposure, relative humidity/water, and concentration of various industrial pollutant gases.
The importance of spectral distribution and intensity of artificial light sources in UV and IR region of radiation for accelerated ageing of polymers
Authors: Boxhammer Jörg , Rudzki T. 
Published: April 2003

AbstractIn recent years increasing importance has been attached to modified, extended and new kinds of test tasks, such as‐ the action of radiation at a simultaneous extreme thermal stress;‐ synergistic influence of the climate (primarily radiation) and e. g. mechanical stress;‐ testing of structural parts and systems (with the requirement of large irradiation surfaces).This aspect as well as primarily ergonomic reasons in the field of the conventional accelerated light exposure and weathering tests in machines have stimulated the discussion about alternative light sources beside the time‐tested Xenon radiation appropriate for the simulation of solar radiation, they have initiated quite a number of scientific investigations, and have now found their first realization in the correspondig machines and equipment.New findings in the application of special metal halide lamps and fluorescent tubes as alternative light sources for Xenon radiation are being discussed on the basis of some typical results.The importance of the infrared part in the artificial radiation to simulate particular phenomena of deterioration is shown with the help of an example of specific problems in the automobile industry, and the transfer of these findings into especially developed and problem‐oriented machine and equipment technology will be discussed.
Coating polycarbonate with acrylics will improve its weatherability
Authors: Hennig Jürgen 
Published: April 2003

AbstractA problem of protecting polymers against weather influences is to concentrate the protective agents (UV‐absorbers, antioxidants etc.) in the adequate place: the surface layer where photocxidative reactions primarily set in. The outstanding properties of polycarbonate (PC) are high levels of toughness and heat resistance whereas polymethylmethacrylate (PMMA) exhibits brilliant transparency and excellent weatherability. Mainly because of its higher spectral energy absorption from global radiation in the critical range from 300 to 400 nm wavelength PC is inferior to PMMA in weatherability: yellowing and erosion within a 20 μm surface layer of PC become visible after 5 years natural weathering. So the idea suggested itself to combine the favourable properties of these two polymers by coating PC with acrylics. As far as weathering results are available today this idea turned out to be very useful: the improvement in weatherability by coating PC regarding the yellowness index, light transmittance and surface erosion is a factor 2–3 in time and even more.