bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methoden zur bestimmung des maleinsäureanhydridgehaltes in acrylnitril‐copolymeren in gegenwart initialer carboxygruppen
Authors: Ziegler Hans‐Jörg , Lehmann Ingeburg , Abel Christiane , Malsch Günter 
Published: April 2003

AbstractZur Bestimmung des Maleinsäreanhydrid(MSA)‐Gehaltes in Acrylnitril(AN)‐Copolymeren des Typs Poly(AN‐co‐MSA) bzw. Poly(AN‐co‐Styrol‐co‐MSA) wurden drei verschiedene Titrationsmethoden hinsichtlich ihrer Richtigkeit, Reproduzierbarkeit sowie ihres Zeitaufwandes geprüft. Miteinander verglichen wurden (i) eine Methodenkombination A/H bestehend aus dem Teilschritt A, einer Umsetzung der Anhydridgruppen (AG) mit Anilin einschließlich der Titration der Monosäuregruppen mit methanolischer KOH, und dem Teilschritt H, einer vollständigen Hydrolyse der AG und Titration der Säuregruppen (SG) mit wäßriger NaOH, (ii) Methode B basierend auf der Reaktion der AG mit n‐Butylamin (BA) und der Rücktitration des nicht umgesetzten Amins mit Perchlorsäure (HClO4) in Eisessig und (iii) Methode C, beruhend auf der Umsetzung der AG mit p‐Chloranilin (pCA) und nachfolgender Chlorbestimmung durch Schöniger‐Aufschluß. Während sich alle genannten Methoden prinzipiell für die AG‐Bestimmung in Gegenwart initialer SG empfehlen, ist darüber hinaus über A/H eine simultane Bestimmung von AG und SG möglich. Wegen dieses zusätzlichen Informationsgewinns, ihrer besseren Reproduzierbarkeit, der erhöhten Richtigkeit sowie des geringeren zeitlichen und apparativen Aufwandes ist die Kombination A/H zu favorisieren. Mit Hilfe der FTIR‐Spektroskopie wurde der Gehalt an AG und SG qualitativ verfolgt und eine Korrelation zwischen den Bandenintensitäten der AG und den potentiometrisch erhaltenen Werten gefunden.
Influence of structural parameters on the dynamic mechanical properties of polyacetals
Authors: Braun Dietrich , Ross Stefan 
Published: April 2003

AbstractThe dynamic mechanical behaviour of various polyacetals was determined by means of torsion pendulum measurements. The products used had different structural parameters such as molecular weight distribution or comonomer nature and content, respectively; thus it was possible to investigate the influence of these parameters on the temperature dependence of the storage modulus G′, which is a measure for the rigidity of the material, and the loss tangent tan δ from ‐100 to 160°C.The storage moduli G′ are not influenced by different molecular weight distributions, but correlate with the crystallinity in the samples, which is, beside others, dependent on the concentration of the incorporated comonomer components. A decreasing crystallinity ‐ i.e. an increasing comonomer content ‐ is combined with a loss in rigidity.The distance between the peak location of the α‐relaxation in the loss tangent curves and the melting points (differential scanning calorimetry) of the investigated acetal resins is nearly constant; thus the molecular motions causing the β‐process take place in the crystalline regions. The α‐process (around −7°C) arises predominantly from molecular motions of the comonomer units, whereas the intensity of this relaxation can be correlated with the mobility of these units. The peak of the γ‐relaxation is located around −67°C and does not hardly shift despite of different structural parameters in the sample, whereas its intensity decreases with increasing both comonomer contents and contents of low‐molecular‐weight components.For unimodally distributed polyacetals with different comonomer contents, the intensity of the β‐relaxation increases with increasing comonomer contents; simultaneously the intensities of the α‐ and γ‐relaxatìon decrease.
Melt free‐radical grafting of glycidyl methacrylate onto polypropylene
Authors: Sun Yi‐Jun , Hu Guo‐Hua , Lambla Morand 
Published: April 2003

AbstractThis paper concerns free‐radical grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) in the molten state carried out in a batch mixer. This free‐radical grafting proceeds very rapidly as it goes to completion within two to three minutes at 200°C. The grafting yield of GMA alone is low and it is greatly enhanced upon addition of styrene as a second monomer with a reduced chain degradation of PP. Homopolymer and copolymer of GMA formed during grafting were quantified. It is suggested that in the presence of styrene, the dominating grafting mechanism is that styrene reacts with the PP macroradicals to form more stable styryl macroradicals which then react with GMA to form GMA‐grafted PP. The rate of this reaction is much greater than that between the PP macroradicals and GMA. Unlike grafting of mixtures of maleic anhydride and styrene, which is dictated primarily by formation of a charge transfer complex, free‐radical grafting of GMA in the presence of styrene follows a random copolymerization process.
Synthesis and characterization of a naphthoquinonediazide positive photoresist derived from bis(hydroxymethyl)phenol
Authors: Liu Jui‐Hsiang , Liu Huang‐Tsai , Tsai Fu‐Ren 
Published: April 2003

AbstractA new photosensitive naphthoquinonediazide (NQD) was synthesized from 2,6‐bis‐(hydroxymethyl)‐3,4‐dimethylphenol and toluene diisocyante. NQD was identified by using IR, NMR and elemental analyses. Photobleachable characteristics were evaluated by UV spectrophotometry. Applications of the NQD on the photolithography as a positive working photoresist were investigated. The aqueous solution of NQD, novolak, cellosolve acetate, and DMF was used as a photosensitive material. It was found that NQD synthesized in this investigation can be used as an effective component in a positive photoresist. Optimal conditions of the UV dose, coating thickness, and development of the resist system were estimated. Resolution of the positive resist was evaluated by SEM technique. Effects of UV dose, exposure time, development time, and exposure UV wave length on the sensitivity and resolution of the photoresist were investigated.
Modified syndiotactic polypropene: Poly(propene‐co‐octene) and blends with atactic oligopropene
Authors: Jüngling Stephan , Mülhaupt Rolf , Fischer David , Langhauser Franz 
Published: April 2003

AbstractPropene and 1‐octene were copolymerized with the syndiospecific homogeneous metallocene catalyst Me2C(Cp)(Flu)ZrCl2/MAO. Large amounts of octene were incorporated randomly. While catalyst activity was not affected markedly by low octene content, molecular weight, crystallinity, Young's modulus, and glass transition temperature were reduced with increasing octene content. Blends of atactic oligopropene with syndiotactic polypropene and poly(propene‐co‐octene) were prepared from toluene solution and compared with a reactor blend prepared with a hybrid catalyst containing a mixture of syndiospecific Me2C(Cp)(Flu)ZrCl2/MAO and non‐specific Cp2ZrCl2/MAO. Atactic oligopropene acted as plasticizer reducing Young's modulus and glass transition temperature of the blends.
Investigations on free radical polymerization of phenyl‐substituted 2‐methylene‐1,3‐dioxanes
Authors: Schulze Thomas , Klemm Elisabeth 
Published: April 2003

AbstractWe have investigated the free radical polymerization of phenyl‐substituted 2‐methylene‐1,3‐dioxanes. It was shown that there is a basic tendency of such ketenacetals to undergo exclusively a vinyl polymerization forming high‐molecular polyacetals without any detectable ring opening. The polymerization with the desirable ring opening reaction cannot be controlled by factors like resonance stabilized chain ends or steric hindrance in the growing step.From densitometric measurements we got new information about the shrinkage behaviour. It was demonstrated that bulky substituents attached to the 2‐methylene‐1,3‐dioxane system result in a significant low shrinkage in homopolymerization and the shrinkage of common comonomers can be decreased by copolymerization.
Acrylamide polymerization in concentrated bicontinuous systems
Authors: Vašková V. , Klimová M. , Bartoň J. 
Published: April 2003

AbstractThe polymerization of acrylamide (AAM) in concentrated bicontinuous microemulsion systems was studied. The locus of initiation using radical initiators with various water‐solubility was investigated. It was found that water‐soluble and partially water‐soluble initiators initiate the AAM polymerization in the reaction systems under investigation very effectively. The polymers thus formed have special structures dependent on the composition of the original concentrated bicontinuous microemulsion.
Grundlagen der Festphasenpfropfung von Polypropylen: Diffusion und Sorption von Pfropfkomponenten im PP‐Granulat
Authors: Rätzsch Manfred , Bucka Hartmut , Wohlfahrt Christian 
Published: April 2003

AbstractBei der Festphasenpfropfung von Polymeren spielen die Diffusion und die Gleichgewichtssorption eine entscheidende Rolle bei der Bestimmung der örtlichen Konzentration der Monomeren in Polymerpartikeln. Mit den vorgestellten Arbeiten ist es gelungen, die Fragen der Gleichgewichtssorption und der Diffusion verschiedener Komponenten im Polypropylen (PP) zufriedenstellend zu klären. Die Kombination von kinetischen und thermodynamischen Messungen mit einem modernen thermodynamischen Modell hat sich bewährt. Die Annahmen und Näherungen bei der Modellierung haben sich als akzeptabel erwiesen und ein schlüssiges Gesamtbild des Verhaltens der Modifikatoren im Polypropylenpartikel ermöglicht. Für die Beschreibung der Diffusionsgeschwindigkeit hat sich ein einparametriges Modell als ausreichend erwiesen. Durch eine Trennung der Transportwiderstände in Poren‐Diffusion und Festphasen‐Diffusion im amorphen Bereich können die experimentellen Daten nicht besser beschrieben werden.
Fully aromatic copoly(ester‐imide)s with high thermal stability
Authors: Gedan‐Smolka Michaela , Jehnichen Dieter , Komber Hartmut , Voigt Dieter , Böhme Frank , Rätzsch Manfred 
Published: April 2003

AbstractFully aromatic copoly(ester‐imide)s of various compositions were synthesized in bulk by conversion of N‐(3‐acetoxyphenyl)trimellitic acid imide and N‐(2‐methyl‐4‐acetoxyphenyl)trimellitic acid imide with 4‐acetoxybenzoic acid as comonomer. The solid state properties, the melting and phase behaviour of the copoly(ester‐imide)s differ largely, but all of them show high thermal stability. Some of the copoly(ester‐imide)s form mesophases in the melt.Most of the investigated copoly(ester‐imide)s of N‐(3‐acetoxyphenyl)trimellitic acid imide and 4‐acetoxybenzoic acid and some of the ternary systems could be processed from the melt. Copoly(ester‐imide)s of N‐(2‐methyl‐4‐acetoxyphenyl)trimellitic acid imide and 4‐acetoxybenzoic acid, however, do not melt before rapid degradation at temperatures above 480°C.
Orientierung von Bacteriorhodopsin in einer Polymermatrix
Authors: Balfanz Friedhelm , Schwarz Hans‐Hartmut , Richau Klaus , Elling Burkhard 
Published: April 2003

AbstractBacteriorhodopsin ist Bestandteil der sogenannten Purpurmembran des Mikroorganismus Halobacterium halobium. Es zeigt photochemische Aktivität und kann als biologischer Lichtwandler fungieren. Voraussetzung hierfür ist eine orientierte Anordnung der Purpurmembran in einer Matrix.Das Prinzip der ionotropen Gelbildung, d. h. die geordnete Strukturbildung einer Polyelektrolytlösung infolge eines gerichteten Diffusionsstromes von mehrwertigen Ionen gestattet die orientierte Anordnung der Purpurmembran. Durch Lichteinwirkung werden elektrische Signale induziert. Es besteht ein Zusammenhang zwischen der Richtung des Strahlungseinfalls und der durch die Gelwachstumsrichtung festgelegten Orientierung der Purpurmembran.
Radiation‐induced copolymerization of methacrylic and acrylic acid with acrylamide
Authors: Georgieva M. , Arabadjieva T. , Tsankov C. 
Published: April 2003

AbstractA study was made of the γ‐radiation‐induced bulk copolymerization of the methacrylic acid‐acrylamide (M2) (MA‐AAm) and acrylic acid‐acrylamide (M2) (AA‐AAm) monomeric pairs. The copolymerization reactivity ratios deterined according to the Kelen‐Tüdő method were: r1 = 1.35, r2 = 0.22 for the MA‐AAm pair, and r1 = 1.75, r2 = 0.10 for the AA‐AAm pair. It has been established that the polymerization rate depends both on the composition of the starting reaction mixture and on the reaction temperature. The differential kinetic curves obtained are unimodal ones, suggesting the occurrence of only one process, i.e. copolymerization. A second maximum in these curves, appearing at elevated temperature, is explained by crosslinking and formation of a water‐insoluble fraction. The copolymers obtained are white powders; in contrast to their water‐insoluble fractions, the water‐soluble ones are not toxic but they are less active as immunomodulators.
Metal ion sorption ability of poly(4‐vinylpyridine‐co‐N,N‐dimethylacrylamide)
Authors: Rivas B. L. , Maturana H. A. , Pereira E. 
Published: April 2003

AbstractResins containing amide and 4‐vinylpyridine moieties were synthesized by radical polymerization. All the resins were completely insoluble in water and characterized by FT‐IR spectroscopy, elemental analysis and thermal analyses. The ability to bind Cu(II), Fe(II), Fe(III) and U(VI) ions at different pHs was studied by batch equilibrium procedure. Uranium(VI) was adsorbed at pH 1 above 50% by the resins 1 and 2. The selectivity of uranium(VI) respect to copper(II) at pH 1.0 was 2.11. The uraniumloaded resin 2 could be partially recovered by treatment with H2SO4 and Na2CO3.
Synthesis and characterization of modified phenolics and their application as curing agent for epoxies
Authors: Patel R. T. , Patel S. P. , Patel R. D. 
Published: April 2003

AbstractA series of novolak type resins were prepared by reacting formaldehyde with various phenoxy acetic acids using HCl as catalyst. All the synthesized resins were characterized by spectral studies (IR), viscometric measurements and by estimating the numberaverage molecular weight by vapour‐pressure osmometry. Two of these resin samples were used as curing agents for epoxy resins for studying the kinetics of curing by DSC technique. The cured epoxies were tested for thermal stability. These resins impart very good heat resistance to epoxy systems.
Tack of pressure‐sensitive adhesives with 4‐nonylphenol formaldehyde novolac resins as tackifiers
Authors: Roşu Dan , Caşcaval Constantin N. , Simionescu Cristofor I. 
Published: April 2003

AbstractThe tack, expressed as the rolling friction coefficient of some pressure‐sensitive adhesives obtained on the basis of natural rubber and 4‐nonylphenol formaldehyde novolac resins of viscosities in the range of 13.6–2065·7 Pa · s, was measured at 20°C by rolling motion of a ball as a function of the nature of the resin in adhesives, its concentration, thickness of the adhesive and velocity of the ball. The maximum amount of the tackifier resin to be used for a high tack of an adhesive depends on the type of resin and its solubility in the rubber phase. The tack of the tested adhesives is a function of the rheological properties. The correlation found between the apparent shear viscosity and the rolling friction coefficient showed that the best results are obtained for rubber‐resin mixtures with viscosities ranging within 1.7 · 106 and 3.4 · 108 Pa · s.
Synthesis and properties of fiber‐grade poly(trimethylene terephthalate)
Authors: Traub H. L. , Hirt P. , Herlinger H. , Oppermann W. 
Published: April 2003

AbstractPoly(trimethylene terephthalate) was synthesized on a semi‐technical scale following the trans‐esterification route. Ester exchange as well as polycondensation were catalyzed by titanium tetrabutylate. The polymer formed shows a remarkable degree of whiteness, contrary to poly(ethylene terephthalate) when synthesized with the aid of titanium compounds. Polymers having molar masses up to 70000 (weight average) were obtained suitable for melt spinning. The Mark‐Houwink parameters for solutions in 1,1,2,2‐tetrachloroethane/phenol (1 : 1, w/w) were determined using static light scattering as a calibration. The melt volume index (235°C, 1.2 kg) was typically in the range 20–30 mL/10 min for a polymer having a weight‐average molar mass of 50000–60000 g mol−1.
Synthesis of chemically bonded poly(vinyl alcohol)‐starch composite
Authors: Hashem Mohamed M. , Bach Elke , Kesting Wolfgang , Hebeish Ali A. , Schollmeyer Eckhard 
Published: April 2003

AbstractPoly(vinyl alcohol) (PVA) was grafted on hydrolysed starch through introduction of the chemically reactive bifunctional compound N‐methylolacrylamid (N‐MAm). The grafting reaction was carried out in two separate reaction steps. The first step was the reaction of PVA with N‐MAm in alkaline medium. The reaction mechanism and reaction conditions such as alkali concentration, temperature, reaction time as well as N‐MAm concentration were studied. According to the results obtained, the most appropriate conditions for the preparation of this reactive PVA are: treating PVA with N‐MAm (1.25 mol/mol PVA) in the presence of NaOH (6% based on solution volume) at 20°C for 8 h. Second step was the reaction of this reactive PVA (N‐MAm‐PVA) with hydrolysed starch in the presence of NH4Cl. The latter was carried out under different conditions including temperature, reaction time, catalyst concentration as well as N‐MAm‐PVA/hydrolysed starch ratio. The results obtained show that the extent of the grafting reaction is governed by each of these factors. Furthermore, GPC data showed that the molecular weight distribution and the apparent viscosity of PVA‐N‐MAm‐starch composite depend on the initial molecular weight of both PVA and hydrolysed starch used.
Sulfonated polyurethane ionomers in solution
Authors: Robilǎ Gabriela , Buruianǎ Tinca , Buruianǎ E. C. 
Published: April 2003

AbstractAqueous and DMF‐diluted solutions of polyurethane ionomers with sodium propanesulfonated groups at urethanic nitrogen atoms were studied by viscometry. A polyelectrolyte effect was evidenced at temperatures between 25 and 60°C, and it was preserved when NaCl was added to solutions.The coulombic interactions between charged groups and a tendency to aggregation in separated domains (favoured by specific molecular architecture of polymers) explain the observed solution properties.
Synthesis and characteristics of chiral polymers with camphanediol moieties
Authors: Liu Jui‐Hsiang , Tsai Fu‐Ren , Lai Yuh‐Chung 
Published: April 2003

AbstractOptically active exo,exo‐2,3‐camphanediol (CPO) was synthesized from (+)‐camphor. The chiral polymers poly(CPO‐co‐TDI) and poly(CPO‐co‐IPDI) were synthesized by step polymerization of chiral compound CPO with toluene‐2,4‐diisocyanate (TDI) and isophorone diisocyanate (IPDI). Effects of solvents, reaction time and temperature on the polymerization were investigated. To investigate the stereo structure of the chiral polymers, two kinds of model compounds, exo‐exo‐2,3‐bornylene N,N′‐diphenyldicarbamate and exo,exo‐2,3‐bornylene N,N′‐dipropyldicarbamate, related to the prepared polymers were synthesized. Chiroptical characteristics and stereo structures of the chiral polymers were investigated by using a circular dichroic spectrometer. Effects of temperature and solvents on the specific rotation of the chiral polymers were evaluated. The results obtained in this investigation suggest that the synthesized chiral polymers have no one‐handed helix conformation.
Effect of substitution of monoester by diester on titanium‐magnesium catalyst properties in propene polymerization
Authors: Talapatra Subhasis , Dudchenko Vyacheslav K. , Bukatov Gennadii D. , Zakharov Vladimir A. , Okkel Lidiya C. 
Published: April 2003

AbstractTitanium‐magnesium catalysts (TMC), containing monoester (ethyl benzoate) as internal donor, can be transferred to the diester TMC by the treatment with TiCl4 and dibutyl phthalate. The activity and the stereospecificity of the transferred TMC in propylene polymerization are close to those of TMC prepared directly in the presence of diester. The surface area and the porous structure of both types of TMC were studied and the correlation with the activity of these catalysts is discussed.
Physical, dynamic‐mechanical and thermogravimetric analysis of aromatic and cycloaliphatic‐based poly(urethaneurea)s
Authors: Cascella Ciro , Malinconico Mario , Martuscelli Ezio , Piermattei Alessandro , Ragosta Giuseppe , Rizzo Adriana 
Published: April 2003

AbstractExperimental batches of linear rubber‐like polyurethanes characterized by the presence of chemically different hard segments are studied and their thermal and dynamic‐mechanical properties are related to the differences in chemical compositions. Interesting correlations are found between the development of crystallinity in such elastomeric poly(urethaneurea)s and the aromatic or alicyclic nature of the diisocyanate. Moreover, for a fixed ratio between hard and soft segments, and for a given composition of the soft segment, the results seem to indicate a better degree of phase separation in cycloaliphatic‐based hard segment poly(urethaneurea)s than in aromatic‐based hard segment poly(urethaneurea)s.
Photopolymerization of styrene and methyl methacrylate using macro photoinitiators. Synthesis and characterization of PS‐PEG‐PS or PMMA‐PEG‐PMMA block copolymers
Authors: Cakmak Ismail 
Published: April 2003

AbstractMacro photoinitiators based on poly(ethylene glycol)s (PEG) bearing benzoyl xanthate moieties were synthesized by the reaction of PEG xanthates with benzoyl chloride. These macro photoinitiators possessing PEGs of different molecular weights were used in the photoinduced radical polymerization of styrene (S) and methyl methacrylate (MMA) to yield block copolymers having an inner‐PEG segment. The influence of the concentration of reactants and polymerization time on the yield and intrinsic viscosities of block copolymers were also investigated. Characterization of block copolymers was carried out by fractional precipitation and IR, UV and 1H NMR spectroscopic methods.
The synthesis of pyridyl‐substituted polyurethanes and copolyurethanes
Authors: Dzo‐Song‐O  , Bouchal Karel , Bleha Miroslav , Kříž Jaroslav 
Published: April 2003

AbstractNew reactive polyurethanes with structure units substituted with pyridine rings were prepared by the polyaddition reaction of diphenylmethane‐4,4′‐diisocyanate or dicyclohexylmethane‐4,4′‐diisocyanate with 2‐methyl‐2‐(4‐pyridyl)propane‐1,3‐diol (MPyP). Copolyurethanes based on this diol were synthesized by a one‐ or two‐step procedure carried out in bulk or diglyme solution using hexane‐1,6‐diol (HD), α,ω‐dihydroxypoly(oxyethylene)s of various molecular weights (POE 400, 1000 and 2000) or α,ω‐dihydroxypoly(oxypropylene) (PPO 400) as comonomers.Pyridyl‐substituted polyurethanes and copolyurethanes were characterized by their 1H and 13C NMR spectra and limiting viscosity numbers [η]. The pyridine units were determined acidimetrically (HClO4). The reactivity of the OH groups of the pyridine diol towards NCO groups was characterized by determining the rate constants of its reaction with phenyl isocyanate. The obtained value of 2.45 × 10−3 dm3 mol−1 s−1 (25°C) was by an order of magnitude greater than the rate constant for the addition of hexane‐1,6‐diol. This difference was interpreted in terms of a catalytic mechanism for the addition of MPyP.