bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photolytic crosslinking of poly(p‐hydroxystyrene)
Authors: Nakabayashi Kenichi , Schwalm Reinhold , Schnabel Wolfram 
Published: April 2003

AbstractLight‐induced crosslinking of poly(p‐hydroxystyrene) (PPHS) is significantly enhanced by O2. This was evidenced by molar mass (light scattering measurements) and by gel content determinations which were performed on various polymer samples before and after continuous irradiation at λinc = 254 nm. The following mechanism was elucidated with the aid of flash photolysis studies: Crosslinking in the absence or presence of O2 is mainly due to the combination of phenoxyl type radicals. In the absence of O2 the latter are exclusively formed by OH bond cleavage of singlet excited phenolic groups. Triplet excited phenolic groups which are also formed do not deactivate via OH bond cleavage but react very effectively with O2. This reaction leads to the formation of HO and additional phenoxyl type radicals. All Commercial and most laboratory‐prepared PPHS samples contain chemically bound impurities of quinoid nature. On the basis of results performed with model compounds of low molar mass, it is concluded that triplet excited quinoid groups react effectively with phenolic groups forming phenoxyl type radicals and that they are quite unreactive with respect to the abstraction of alphatic hydrogen atoms. Irradiation of PPHS at λinc = 254 nm causes the formation of quinoid groups which absorb strongly at this wavelength. Light absorption by these groups becomes a determining factor with respect to photochemical alteration in the course of further irradiation.
Multipurpose woven cotton and cotton/polyester blends containing crosslinked polyols affixed by a low temperature cure
Authors: Vigo Tyrone L. , Hao Ping , Bruno Joseph S. 
Published: April 2003

AbstractWoven cotton and cotton/polyester blend fabrics of similar construction were treated with solutions of poly(ethylene glycol) (PEG, Mn of 600, 1000 and 1450 g/mol) containing tetrafunctional dimethyloldihydroxyethyleneureaSystematic name: 1,3‐Bis(hydroxymethyl)‐4,5‐dihydroxyimidazoline‐2‐one.
(DMDHEU) and a mixed acid catalyst. Subsequent curing of these fabrics under selected mild conditions produced fabrics containing bound and crosslinked polyols with several improved functional properties (thermal storage and release, flex and flat abrasion resistance, soil release and hydrophilicity). These functional property improvements are due to structural aspects of the crosslinked polyol. These structural aspects are high latent heat due to energy required to break intra‐ and intermolecular hydrogen bonds and the elastomeric and hydrophilic nature of the polymer in the fiber matrix. When the fabrics were cured under the mildest conditions, these enhanced functional properties were obtained without adversely affecting the softness or hand and the air permeability of these fabrics. Best results were obtained with the PEG‐1000/DMDHEU solutions for an overall balance of improved fabric properties. Relative to untreated fabrics, treated 100% cotton fabrics had the most dramatic increase in their flex life, sometimes over an order of magnitude greater than before treatment and curing.
Alternierende copolymerisation von butadien und ethen
Authors: Arnold M. , Reußner J. , Wohlfarth L. 
Published: April 2003

AbstractEs wurde die Copolymerissation von Butadien und Ethen in Gegenwart des katalysatorsystems Dineopetyloxyvanadiumoxychlorid/Aluminiumtriisobutyl untersucht. Die Variation der grundlegenden Reaktionsparameter [A1]/[V]‐Verhältnis, Zusammensetzung der Monomermischug und Polymerisationstemperature ergab einen signifikanten Einfluß auf den Verlauf der Reaction, den Umsatz der Moomeren die, Molmasse und die Polydispersität der erhaltenen Copolymeren. NMR‐Untersuchngen belegen einen hohen Alternierungsgrad.Bei der Variation des Verhaltnisses der Katalysatorkomponenten wurde ein Maximum für Umsatz und die Molmasse bei einem Verhältnis [A1]/[V] ≈︁ 7 ermittelt. Die Erhöhung des Ethengehaltes in der Moomermischung führt ebenfalls zu einer Erhöhung des Umsatzes. Dabei werden die Molmassen jedoch erniedrigt. Die Variation der Polymerisationstemparatur im Bereich von −25°C bis +40°C ergab für den Umsatz und die Molmasse Abhängigkeiten mit Minimum bzw. Maximum. Bei Polymerisationstemperaturen oberhalb +20°C ist ein Anwachsen der 1,2 ‐Addition des Butadiens und eine zunehmende Vernetzung der Produkte zu verzeichnen.
Synthesis and chemo‐physical properties of hydrogels
Authors: Chen C. M. , Lee T. Y. , Niu Gregory C. C. 
Published: April 2003

AbstractHydrogels are synthesized from methyl methacrylate (MMA) and N‐vinyl‐2‐pyrrolidone (NVP) with 1,1,1‐trimethylol propane trimethacrylate (TPTA) as a crosslinking agent. It was polymerized under UV radiation (365nm) with a small amount of photosensitizer, diethoxy acetophenone (DEAP), acclerator and diluent, triethanol amine (TEA). The hydrogels were characterized by measuring the water retention, dissolved oxygen diffusivity and permeability, mechanical strength, and light transparency. The hydrogels can retain water up to 80 wt.‐% and the mechanical strenght is weakened as the water content is increased in the gel. The dissolved oxygen diffusivity and permeability in the swelling hydrogels are determined to be 10−6 cm2/sec and 1013 cm2s−1 Pa−1, respectively. The light transparency is over 90% in the wave lenght ranging from 500 to 700 nm.
Time temperature equivalence in plasticized PVC
Authors: Patel N. K. , Kansara Sujata , Patel C. K. 
Published: April 2003

AbstractThe viscoelastic response of plasticized PVC was determined from stress‐relaxation data over a wide range of time at different temperatures. The relaxation modulus as a function of time was determined from these data. The relaxation curves were then shifted horizontally to obtain a master curve at a reference temperature. The amount of shift was evaluated using the WLF equation. The coefficients C and C used in the equation for the PVC were determined according to the method of reduced variables.
Tough thermoplastic polyesters by reactive extrusion with epoxy‐containing copolymers
Authors: Hert Marius 
Published: April 2003

AbstractPoly(butylene terephthalate) (PBT) and poly(ethylene terephthalate) (PET) are brittle polymers with poor notched impact strength. Their toughening can be achieved by melt blending with different types of rubbery ethylene copolymers containing functions having potential reactivity with the hydroxy and carboxy end groups in polyesters.Two types of ethylene copolymers were investigated: ethylene/ethyle acrylate/glycidyl methacrylate (E/EA/GMA) and ethylene/ethyl acrylate/maleic anhydride (E/EA/MAH) copolymers. The blends were obtained by reactive extrusion of PBT with 10 to 25% of copolymers.PBT blends undergo a brittle to ductile transition by toughening with GMA copolymer between 10 and 20% of rubbery phase. The most effective toughening could be achieved by a partial crosslinking of the rubbery particles obtained by associating GMA and MAH copolymers and a reaction catalyst.
Reaktionsverhalten des Natriumallylsulfonats in der Lösungscopolymerisation des Acrylnitrils in Dimethylformamid
Authors: Fritzsche Peter , Abel Christiane 
Published: April 2003

AbstractIm Copolymerisationssystem Acrylnitril (AN)/Methylacrylat(MA) mit Natriumallylsulfonat (NaAS) in Dimethylformamid wurde die relative Übertragunskonstante zum NaAS Cx = 0,04 ± 0,01 unabhängig vom verwendeten Initiator (Azoisobuttyronitril, Ammoniumperoxodisulfat) ermittelt. Die Übertragunsreaktion beschreibt den Einfluß des NaAS auf den Polymerisationsgrad, sie beeinflußt jedoch den Copolymerisationsparameter r1 nur in der Größenordung von 1 bis 5% und kann damit die Konzentrationsabhängigkeit von r1 nicht erklären.Mit Hilfe der erweiterten Debye‐Hückel‐Theorie für verdünnte Elektrolyte wird die Abhängigkiet des r1‐Wertes von der NaAS‐ Konzentration beschrieben. Der sich daraus für unendliche Verünnung des NaAS ergebende r10‐Wert ist offensichtlich noch gerinfügig von der Acrylnitrilkonzentration abhägig. Er liegt beispielsweise für [AN] = 4, 26 mol/1 bei r10 = 0, 32. Damit wurde zum ersten Mal das nichtideale Copolymerisationsverhalten im untersuchten System erkärl. Das Vorgehen sollte verallemeinerungsfähig sein und generell auf das Copolymerisationsverhalten von Monomeren mitdissoziierten Gruppen angewendet werden können.
Effect of ring size on the oxidizability of lactams
Authors: Lánská Božena , Makarov Genadii G. , Šebenda Jan 
Published: April 2003

AbstractThe initial stage of oxidation of lactams was studied in the temperature range 70–120°C. It was found that pyrrolidone and piperidone are oxidized essentially more easily than the seven‐, eight‐, nine‐ and thirteen‐membered lactams as well as linear N‐alkylamides. The high oxidizability of the five‐ and six‐membered lactams may be attributed to the easier homolytic splitting of the N‐vicinal CH bond and to the different reactivity of lactam radicals in the propagation step of the chain oxidation.
Photosynthetic membranes, 21. Immobilization of catalase by photochemically grafted ultrafiltration membranes
Authors: Selli Elena , Bellobono Ignazio Renato , Raimondi Maria Luisa 
Published: April 2003

AbstractCatalase has been immobilized in membranes prepared by photoinduced grafting onto microporous polymeric supports and its catalytic activity on hydrogen peroxide decomposition has been studied under ultrafiltration conditions by means of a recirculation apparatus. The membranes showed a very good catalytic performance and the enzyme reaction took place exclusively within the membrane structure. Initial reaction rates measured in the temperature range 5 – 35°C as a function of both substrate concentration and enzyme amount immobilized per unit membrane surface indicate that the mechanism of action of catalase is not altered after immobilization.
Untersuchungen zum Netzwerkbildungsprozeß bei der Reaktion von Bisphenol A‐Diglycidylether mit 4,4′‐Diaminodiphenylmethan
Authors: Strehmel Veronika , Fryauf Kerstin , Sommer Claudia , Arndt Karl‐Friedrich , Fedtke Manfred 
Published: April 2003

AbstractDer Aufbau von Netwerken aus Bisphenol A‐Diglycidylether und 4,4′‐Diaminodiphenylmethan wurde durch Messung des Drehmomentes, der Leitfähigkeit und durch Bestimmung der löslichen Anteile des vernetzenden System untersucht. Aus den Gelzeiten wurden die Aktivierungsenergie für den Vernetzungsprozeß bestimmt. Außerdem wurde die während der Vernetzung aufretende Volumenschwindung gemessen. Der Einfluß von N, N‐Dimethylbenzylamin als Beschleuniger auf den Vernetzungsprozeß wird diskutiert.
Crystallization and thermal behaviour of isotactic polypropylene blended with an alicyclic random co‐oligomer
Authors: Canetti Maurizio , Bonfatti Anna Maria , Siciliano Antonio , Seves Alberto 
Published: April 2003

AbstractA fully saturated, alicyclic hydrocarbon resin (IST) was blended with isotactic polypropylene (iPP). IST is a random co‐oligomer of low average molecular weight obtained by oligomerization of indene, α‐methyl styrene and vinyl toluene, followed by hydrogenation.The crystallization and thermal behaviour of iPP/IST blends were analyzed by microscopy and differential scanning calorimetry (DSC). The influence of blend composition on the spherulite growth rate and on the overall crystallization rate suggests that the two components form a miscible blend in the amorphous phase, as confirmed by the following observations: All blends show a single glass transition temperature (Tg); its value, depending on composition, lies between the iPP and IST Tg values (–14°C and 82°C, respectively), and is in good agreement with the theoretical values calculated by the Fox equation. The equilibrium melting temperature calculated for pure iPP was equal to 187°C; this value decreases with blending to 175°C for the iPP/IST 50/50 (w/w) blend. The χ12 parameter of the iPP/IST system was equal to −0.435, the negative value should suggest that the two components can form a compatible mixture which is thermodynamically stable above the equilibrium melting temperature.
Synthesis and thermal properties of copoly(1,4‐arylene‐1,2,4‐oxadiazole)s with dimethyl substituent
Authors: Jung Jin Chul , Choi E.‐Joon 
Published: April 2003

Abstract2,5‐Dimethyl terephthalamide oxime (DTD) was prepared from 2,5‐dimethyl terephthalonitrile, and various mixtures of DTD and terephthalamide oxime (TD) were condensated with terephthaloyl chloride in dimethyl acetamide. The obtained homo‐ and copoly(terephthaloyl terephthalamide oxime)s with two methyl substituents were characterized and cyclodehydrated to give rise to corresponding homo‐ and copoly (1,4‐arylene‐1,2,4‐oxadiazole)s with two methyl substituents as the side branch.Thermal properties of the homo‐ and copoly(1,4‐arylene‐1,2,4‐oxadiazole)s were investigated and the effects of the methyl groups were determined and discussed. The introduction of methyl substituents improved the solubility of the copoly(1,4‐arylene‐1,2,4‐oxadiazole)s greatly, but lowered their thermal resistance. All the copolymers and the homopoly [1,2,4‐oxadiazole‐5,3‐diyl‐(2,5‐dimethyl‐1,4‐phenylene)‐1,2,4‐oxadiazole‐3,5‐diyl‐1,4‐phenylene] were found to be amorphous with no observable glass transition.
Metal complexation of poly[1‐(2‐hydroxyethyl)aziridine‐co‐2‐methyl‐2‐oxazoline] in aqueous solution
Authors: Geckeler Kurt E. , Zhou Rongnong , Rivas Bernabé L. 
Published: April 2003

AbstractThe metal complexation of water‐soluble poly[1‐(2‐hydroxyethyl)aziridine‐co‐2‐methyl‐2‐oxazoline] with Co(II), Zn(II), Ni(II), Cu(II), Cr(III), Fe(III), Cd(II), Pb(II), and Sr(II) ions was investigated in aqueous phase using Liquid‐Phase Polymer‐Based Retention (LPR). The study shows that all metal ions are complexed at pH 5, except Co(II) and Zn(II). In contrast to Sr(II), which showed only a slight interaction over a pH range of 3 to 7, 94% of Co(II) and 88% of Zn(II) were retained at pH 7. At pH 3, only Cu(II) and Cr(III) ions interacted with the copolymer with retention values of 76% for Cu(II) and 52% for Cr(III). Viscosimetric measurements of the copolymer were performed in the presence of metal ions at different pH values.
Glass fiber‐reinforced epoxy composites
Authors: Patel Sandeep R. , Patel Ranjan G. 
Published: April 2003

AbstractGlass fiber‐reinforced epoxy composites were prepared from the matrix resins tetraglycidyl diaminodiphenylmethaneSystematic name: N,N,N′,N′‐Tetrakis(2,3‐epoxypropyl)‐4,4′‐diaminodiphenylmethane.
(TGDDM) and tetraglycidyl bis(o‐toluidino)‐methaneSystematic name: N,N,N′,N′‐Tetrakis(2,3‐epoxypropyl)‐4,4′‐bis(o‐toluidino)methane.
(TGMBT) using various amines like 4,4′‐diaminodiphenylmethane (DDM), 4,4′‐diaminodiphenylsulfone (DDS) and diethylene triamine (DETA) as curing agents. The fabricated laminates were evaluated for their mechanical and dielectrical properties and chemical resistance. The composites prepared using an epoxy fortifier (20 phr) showed significant improvement in the mechanical properties.
Investigation of synthesis and light stability of polymeric azo dyes. II. Polymeric acrylate‐azo dyes
Authors: Lewandowsky Ekkehart , Mayer Roland , Marx Jörg , Böttcher Horst 
Published: April 2003

AbstractDifferent 4′‐substituted 4‐[N‐ethyl‐N‐(2‐acryloyloxy)ethyl]aminoazobenzenes were used as starting monomers for homopolymerization and copolymerization reactions with styrene and methyl methacrylate. The photofading behaviour of the obtained polymeric azo dyes (M̄n 4200 – 9000) was investigated by means of a Xenotest device and compared with that of the corresponding monomers. The decreased photostability in the order monomer — copolymer — homopolymer was assumed to be caused by an increasing energy transfer in the matrix.
Crystallization of poly(aryl ether ketones). 2. Double peak melting behavior of PEEKK
Authors: Könnecke K. 
Published: April 2003

AbstractAnnealing poly(ether ether ketone ketone) (PEEKK) between glass transition and melting temperature generally results in a pronounced double peak melting behavior as obtained by DSC. Detailed investigations of the dependence of this double peak melting behavior on annealing conditions and experimental parameters clearly reveal that the crystallization can be described by a two‐stage process occurring on different time scales. A recrystallization model as origin for the double peak melting curves can be disproved.
m‐Bromophenolic epoxy resins for electronic packaging
Authors: Wang Chun‐Shan , Lin Yong‐Sheng , Fritz David B. 
Published: April 2003

AbstractMeta‐halogenated phenols are generally known to be more chemically and thermally stable than their ortho‐ or para‐halogenated counterparts. A reactive intermediate, produced by the bromination of 2,4,6‐trimethylphenol is being used as an alkylating agent to incorporate this stable m‐bromophenol moiety into varieties of organic compounds and polymers. In electronic encapsulation applications, epoxy derivatives of novolacs containing m‐bromophenol have exhibited superior hydrolytic and thermal stability as compared with the conventional tetrabromo bisphenol‐A epoxies which are ortho‐brominated phenolics. The m‐bromophenol moiety contributes to the extended device reliability while meeting flame retardency requirements as well.
Bonding of rhenium(V) to diethylenetriaminepentaacetate functional groups of a polymethacrylate support
Authors: Hoskovcová I. , Kálalová E. 
Published: April 2003

AbstractThe bonding of rhenium to diethylenetriaminepentaacetic acid functional groups of a polymeric methacrylate matrix was studied. Diamagnetic complexes were formed of Re(V) with the heterogeneous coordination sphere containing atoms of chlorine and multiply bonded oxygen in addition to carboxylic groups, which are the only groups of the polymeric support functioning as ligands in the bonding to the metal. The rhenium complexes were examined by IR and UV‐VIS spectroscopy and by magnetic moment measurements.
Investigation of phase equilibria in mixtures composed of ethene, 1‐butene, 4‐methyl‐1‐pentene and a polyethylene wax
Authors: Wohlfarth Christian , Finck Udo , Schultz Ronald , Heuer Tilo 
Published: April 2003

AbstractSome measurements of the vapour‐liquid and/or the demixing equilibrium at moderate pressures were carried out in systems containing the monomers ethene, 1‐butene, 4‐methyl‐1‐pentene and a polyethylene wax. A group‐contribution‐modified chain‐of‐rotators (COR) equation of state was used to calculate the phase diagrams in all binary and ternary subsystems and in the whole quarternary mixture. The calculations lead to a satisfying description of the vapour‐liquid equilibrium and its intersection by a liquid‐liquid region at higher pressures and temperatures. The miscibility gaps in both mixtures of the polyethylene wax with 1‐butene and 4‐methyl‐1‐pentene, respectively, were observed again after adding ethene to these binary mixtures. The calculations indicate a small three phase triangle in all corresponding ternary mixtures. A liquid‐liquid demixing region intersecting the vapour‐liquid surface could also be found in the whole quaternary system by calculation with the modified COR model. This surprisingly complicated phase behaviour has properly to be taken into account during the separation of the monomers after the co‐ or terpolymerization process.
Influence de la quantité d'un sel de sulfonium sur la coupure des liaisons OSi et sur la solubilité d'un mélange renfermant le sel et le poly(p‐triméthylsiloxystyrène) et irradié par des UV
Authors: Bonfils Frédéric , Giral Louis , Montginoul Claude , Sagnes René , Schué François 
Published: April 2003

AbstractSi on laisse vieillir les solutions d'enduction obtenues en solubilisant le poly(p‐tri‐méthylsiloxystyrene) et l'un des sels (C6H5)2(C6H5SC6H4)SSbF6 ou (C6H5)3SAsF6 dans un solvant tel que la 3‐pentanone, on constate que le pourcentage de coupure des liaisons OSi(CH3)3 obtenue après irradiation (λ = 254 nm) avec une dose donnèe et après postcuisson dèpend de la quantitè de sel introduit. I1 en est de même de la solubilité de la rèsine ainsi traitee dans le solvant basique MF 319.
Readily hydrolyzable cellulose esters as intermediates for the regioselective derivatization of cellulose, 1. Synthesis and characterization of soluble, low‐substituted cellulose formates
Authors: Schnabelrauch Matthias , Vogt Sebastain , Klemm Dieter , Nehls Irene , Philipp Burkart 
Published: April 2003

AbstractA new procedure was developed for the synthesis of low‐substituted, soluble cellulose formates. In a mixture containing cellulose, formic acid, phosphoric acid and water, cellulose can be dissolved within several hours, and after 24 h cellulose formates with a DS of about 0.6 that are soluble in DMSO could be obtained. By adding sulfuric acid as a dehydrating agent to the formylating system, formates with DS‐values up to 1.2 that are soluble even in DMF and N,N‐dimethylacetamide are formed after a very short reaction time of 15 min. 13C‐NMR studies show a strongly preferred formylation of the primary hydroxy groups of cellulose. Furthermore, the extent of depolymerization during the formylation reaction was investigated for various cellulose materials.
Synthesis and transition metal complex binding of amines and amides covalently bound to crosslinked polystyrene
Authors: Nicolaus Volker , Wöhrle Dieter 
Published: April 2003

AbstractPolymers containing moieties of amides covalently bound to highly crosslinked polystyrene by CC connections were prepared via a polymer‐bound malonic ester group in the reaction with open‐chain diamines. The reaction of crosslinked, chloromethylated polystyrene with macrocyclic and open‐chain amines results in covalent binding by CN‐connection. The synthesized functionalized polymers were investigated for uptake of Cu(II), Ni(II) and Co(II) ions from aqueous solutions.
Sorptionsverhalten von nativer und thermoplastischer stärke
Authors: Sala R. M. , Tomka I. A. 
Published: April 2003

AbstractEs wurden Wasserdampf‐Sorptionsisothermen von nativer und thermoplastischer Stärke gemessen. Die thermisch‐mechanische Behandlung der Stärke und das Einfähren von Glyzerin als Weichmacher fährt zum Verschwinden der Hysterese und zum Übergang von der Typ II in eine Typ III Isotherme. Eine Theorie, welche das Sorptionsverhalten von quellbaren Sorbentien gut beschreibt, wird kurz eingeführt und anhand der experimentellen Daten ihre Aussagen diskutiert. Die vorgestellte Theorie erlaubt wegen der physikalischen Bedeutung der Parameter Rückschlüsse auf die molekularen Vorgänge während der Sorption. Die Motivation zur Untersuchung des Sorptionsverhaltens von thermoplastischer Stärke ist deren möglicher Einsatz als biologisch abbaubarer Kunststoff.
New unsymmetrical cycloaliphatic epoxypolyesterimides
Authors: Roig Antoni , Serra Angels , Cádiz Virginia , Mantecón Ana 
Published: April 2003

AbstractNew bisepoxy unsymmetrical cycloaliphatic derivatives have been synthesized. The different reactivity of both oxirane rings (cycloaliphatic and glycidylic) has been tested against carboxylic acids giving rise to normal and abnormal opening to the glycidyl group. Homopolymerization reaction was also observed. Polymer structures were identified by 13C‐NMR spectroscopy. Thermal analysis carried out allowed to confirm their good thermal properties.
Mutual correlations between parameters characterizing the miscibility, structure and mechanical properties of polymer blends
Authors: Fekete Erika , Pukánszky Béla , Peredy Zoltán 
Published: April 2003

AbstractPolymer blends were prepared in the whole composition range using polymers of different polarity. Mechanical properties were characterized by tensile measurements. Surface and interfacial properties were measured and calculated and parameters characterizing the miscibility were determined. A correlation was found between the yield stress and the thermodynamic quantities characterizing the degree of miscibility. Since both the degree of miscibility and morphology are influenced by the interfacial tension, it can be regarded as the best candidate to correlate polymer/polymer interaction and mechanical properties in polymer blends.