bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and properties of biodegradable copolyesteramides: Nylon 6,6/ϵ‐caprolactone copolymers, 1
Authors: Arvanitoyannis Ioannis , Nakayama Atsuyoshi , Kawasaki Norioki , Yamamoto Noboru 
Published: April 2003

AbstractA series of copolyesteramides based on adipic acid/1,6‐hexane diamine/ϵ‐caprolactone and Nylon 6,6 salt/ϵ‐caprolactone were synthesized. Their molecular weights, determined by gel permeation chromatography and NMR spectroscopy, were found to lie within the range from 1000 up to 7000. Their thermal properties (glass transitions, melting points and heats of melting, and decomposition temperatures) were recorded with diferential scanning calorimetry and thermogravimetry, respectively, and correlated to the comonomer feed composition. The FT‐IR and NMR spectra were also recorded in order to confirm the composition of the copolyesteramides and to compare them with that of the comonomer feed. The biodegradability of the synthesized copolymers was tested by enzymatic hydrolysis.
Study of the condensation products of abietic acid with formaldehyde at high temperatures
Authors: Bicu Ioan , Mustaţǎ Fǎnicǎ 
Published: April 2003

AbstractNew condensation products have been synthesized by heating abietic acid and formaldehyde at high temperatures in the presence of sulfonic‐type acid catalysts. The main polycondensation reaction is associated with a secondary one which leads to a ketonic compound, carbon dioxide and water. The carboxylic groups of abietic acid participate in this condensation reaction. The behaviour of the abietic acid‐sulfonic acid catalyst system was studied in absence of formaldehyde to acquire additional information about the reaction. The process is defined by the reaction temperature and chemical nature of the catalyst. A possible mechanism of the condensation reaction is discussed on the basis of the obtained results.
Deposition of hydrophobic layers onto acrylic fibers by plasma polymerization
Authors: Occhiello Ernesto 
Published: April 2003

AbstractExperiments aimed at the deposition of hydrophobic coatings on acrylic fiber surfaces are described. The effects of utilizing fluorine‐containing and siloxane monomers and of varying plasma parameters have been assessed by measuring deposition rates, observing surface chemistry and determining water contact angels.
Tailored polymers by cationic ring‐opening polymerization
Authors: Goethals Eric J. , Van Caeter Peter , Geeraert Jan M. , Du Prez Filip E. 
Published: April 2003

AbstractAfter a general classification of the cationic ring‐opening polymerizations (CROP's) according to their polymerization mechanism, a number of examples of tailored polymers based on CROP are presented. The monomers used for the synthesis of these tailored structures are tetrahydrofuran (THF), N‐tert‐butyl aziridine (TBA), 2‐methyl‐1,3‐oxazoline (MeOX) and 1,3‐dioxolane (DXL).The polymer structures include different block and graft copolymers, macromonomers, star‐shaped polymers, polymer networks and interpenetrating polymer networks (IPNs).
Dendritische und “hyperbranched” Polymere. Beispiele für die Beeinflussung von Polymereigenschaften durch gezielte Synthese von dreidimensionalen Strukturen
Authors: Voit Brigitte I. , Turner S. Richard 
Published: April 2003

AbstractDendritic polymers are highly branched structures with globular shape and high number of functionalities. In a divergent or convergent stepwise synthesis perfect macromolecules with controlled size and architecture are obtained. From the broad variety of dendrimer structures some examples are given and the properties of these unusual polymers are illustrated. For comparison the hyperbranched polymers, dendritic structures with defects made in a one‐pot polycondensation reaction, are discussed. Differences and conformities of properties like molecular weight distributions, functionalities, solubility, viscosity behavior and glass transition temperatures for both globular polymer structures are explained.
Massgeschneiderte Polymere. Synthesestrategien für Telechele, Makromonomere, Block‐ und Pfropfcopolymere
Authors: Nuyken Oskar 
Published: April 2003

AbstractNew developments in the synthesis of telechelics, macromonomers, block‐ and graftcopolymers are presented. Synthetic strategies for them are demonstrated with examples from different fields such as polycondensation, radical, anionic, and cationic polymerization, chain cleavage and criss‐cross‐cycloaddition.
Progress in synthesis and application of segmented polymers
Authors: Mülhaupt Rolf , Buchholz Udo , Rösch Joachim , Steinhauser Norbert 
Published: April 2003

AbstractTailor‐made segmented polymers play a key role in the development of novel polymeric materials exhibiting unsual bulk and surface properties. As a function of molecular architectures of segmented polymers, it is possible to control polymer morphologies and to achieve property synergisms. Selected examples are presented to illustrate basic concepts and recent developments. Segmented reactive liquid rubbers, containing an immiscible silicone segment flanked by two miscible oligo(caprolactone) segments, are efficient epoxy toughening agents. In such nano‐phase‐separated silicone‐modified IPNs impact strength is improved without sacrificing dimensional stability. Compatibilized blends of segmented phenolic polyurethane and nitrile liquid rubbers produce rubber blend microphases dispersed in epoxy prepregs which are used to bond aluminum sheets in structural laminates. Reactive blending technologies are developed to produce segmented polymers as blend compatibilizers during melt processing, e.g., of polypropylene/polyamide 6 blends. Incorporation of oligo(tetrafluoroethene) segments into various condensation polymers modifies thermal and mechanical properties as well as surface tension and gas permeabilities.
Neuartige Einkomponenten‐Reaktiv‐Systeme auf basis von festen Polyisocyanaten
Authors: Kopp Richard , Grögler Gerhard , Heß Heinrich , Prolingheuer E. Christoph , Casselmann Holger 
Published: April 2003

AbstractLagerstabile Polyurethan‐Einkomponentensysterne auf Basis von flüssigen oder ver flüssigbaren NCO‐reaktiven Kornponenten und festen, feinteiligen, mit einer Diffusions sperrschicht umhullten TDIH‐Partikeln lassen sich therrnisch zu Elastomeren mit hohem Eigenschaftsniveau, insbesondere hoher thermomechanischer Stabilität, ausharten.Die Eigenschaften der Endprodukte lassen sich in einem weiten Bereich durch die Auswahl der NCO‐reaktiven Aufbaukomponenten steuern. Je nach Viskosität bzw. Schmelzverhalten der Ausgangskomponenten erhält man bei Raumtemperatur gut gießbare, rakelfähige oder auch feste, leicht aufschmelzbare reaktionsfähige Gemische, die, abhängig von ihrer Viskosität und dem Verwendungszweck, nach verschiedenen Methoden verarbeitet werden können (Spritzen, Gießen, Rakeln, Spritzguß, Schleuderguß, Slush‐Molding u.ä.)Die Kombination aus praktisch unbegrenzter Lagerzeit und Verarbeitungszeit, rascher. Härtung bei Temperaturen ab ca. 100°C und breiter Variationsmoglichkeit der mechanischen Eigenschaften eröffnen diesen neuen Polyurethan‐Systemen ein weites. Einsatzgebiet mit interessanten, neuen Möglichkeiten.
Olefinpolymerisation mittels metallocenkatalysatoren
Authors: Kaminsky Walter 
Published: April 2003

AbstractMetallocenes have gained widespread interest as catalysts for olefin polymerization due to their high activity and versatility. A large range of new polymers with narrow molecular weight distribution and different microstructures can be produced with these “single‐site” catalysts. These highly active catalysts which are able to produce 40 tonnes of polyethylene per gram zirconium per hour are even capable of incorporating remarkable amounts of sterically demanding olefins and dienes in copolymerization with ethylene. Isotactic, syndiotactic, stereoblock and isoblock polyolefins are accessible by variation of the metallocene ligands. Similarly, the isotacticity and molecular weight of the generated polyolefins are influenced by the ligand structure. By heterogenization of the metallocene on metal powder or silica polymers with substantially higher molecular weight, higher melting points and other new properties may be attained. Cyclic olefins like cyclopentene, norbornene or dimethanooctahydronaphthalene polymerize without ring‐opening to yield highly melting and poorly soluble polymers. By separation of the racemic catalyst into enantiomers, optically active alkanes and alkenes are accessi‐ble. Trimers are obtained with ee of 95%. These results provide new insights into the mechanism of Ziegler‐Natta catalysis.
Cycloolefin‐copolymere: Eine neue klasse transparenter thermoplaste
Authors: Cherdron H. , Brekner M.‐J. , Osan F. 
Published: April 2003

AbstractInvestigation of the polymerization process and property modification of metallocene‐based cycloolefin copolymers (COC) shows that this monomer‐catalyst combination enables synthesis of a new class of transparent thermoplastic polymers. Metallocene catalysis offers much opportunity to vary the composition and microstructure of the copolymers. The breadth of the polymer spectrum which can be further widened by polymer modification enables many applications for this new class of thermoplastics. The key parameters that control structure and properties in the COC family are discussed in this paper.
Übergangsmetall‐katalysierte kondensations‐ und polykondensationsreaktionen
Authors: Heitz Walter 
Published: April 2003

AbstractWhile metal‐catalysed polymerizations are chain reaction with constant valence of the metal, metal‐catalysed polycondensations are step polymerizations with changing valence of the metal. Taking as examples the Pd‐catalysed vinyl polymerization of norbornene, the alternating copolymerization of ethylene and carbon monoxide, and the Heck reaction, the essential structural prerequisties of the catalyst to control those reactions are presented. Metal‐catalysed polycondensations may occur as one‐ or two‐electron processes. The oxidative polymerization of 2,6‐dimethylphenol, the Heck reaction, and the Ni‐catalysed polyphenylene synthesis are discussed.
Polymersynthesen durch repetitive N‐alkylierungen
Authors: Schulz Rolf C. , Hochberg Gerd , Walter Frank 
Published: April 2003

AbstractThe repetitive N‐alkylation reaction, at first used by Marvel, turned out to be a very versatile method for the synthesis of polycations. Rembaum introduced the name “ionenes” for this type of polymers. In the first part of the lecture some examples of single‐stranded ionenes are described. The second part shows how the repetitive N‐alkylation can be used for the synthesis of spiro polymers. In these double‐stranded polymers two spiro‐conjugated rings of the main chain have a central quaternary nitrogen in common (spiro‐ionenes or spiro‐azonia polymers). Starting from tetrabromides (for instance 1,2,4,5 tetrabromomethylbenzene) and different cyclic diamines soluble polymers (with more or less stretched shape) with the typical properties of polyelectrolytes are obtained.
Intramolekular vernetzte poly(organosiloxan)partikel
Authors: Geck Michael , Deubzer Bernward , Weis Johann 
Published: April 2003

AbstractIntramolecularly crosslinked poly(organosiloxane) particles are prepared by means of emulsion polycondensation or emulsion polymerization of alkoxysilanes or cyclic organic siloxanes. Starting from these intramolecularly crosslinked poly(organosiloxane) particles, graft copolymers are obtained by free‐radical emulsion polymerization of unsaturated olefinic monomers (e.g. acrylates, styrene) in the presence of (functionalized) organosiloxanes. Intramolecularly crosslinked poly(siloxane) particles and their graft copolymers are characterized by means of light scattering (in dispersion), electron microscopy and thermal analyses (DSC, DMTA).
Preparation of multiphase block copolymers by redox polymerization process, 3. Polymerization of methyl methacrylate and acrylamide by the Mn(III)‐poly(ethy1ene glycol) redox system
Authors: Cakmak Ismail 
Published: April 2003

AbstractRedox‐initiated free‐radical polymerization of methyl methacrylate (MMA) and acrylamide (AAm) with poly(ethy1ene glycol) (PEG) using Mn(III) as reduction agent was carried out to yield PMMA‐block‐PEG‐block‐PMMA and AAm‐block‐PEG‐block‐AAm triblock copolymers. The principal parameters (concentration of the reactants, temperature) affecting the synthesis were examined. Block copolymers were characterized by 'H‐NMR and infrared spectroscopy.
Aminosiloxane‐modified epoxy resins as microelectronic encapsulants
Authors: Shieh Jeng‐Yueh , Ho Tzong‐Hann , Wang Chun‐Shan 
Published: April 2003

AbstractAmine‐terminated poly(dimethylsiloxanes) (ATPDMS) were used to improve the toughness of a cresol‐formaldehyde novolac epoxy resin cured with a phenolic novolac resin for electronic encapsulation application. The effect of molecular weight of amine‐terminated polysiloxanes on the phase separation of the resultant elastomers from epoxy matrix were investigated. Mechanical and dynamic viscoelastic properties of siloxane‐modified epoxy networks were also studied. The dispersed silicone rubbers effectively improve the toughness of cured epoxy resins by reducing the coefficient of thermal expansion and flexural modulus, while the glass transition temperature was hardly depressed. Electronic devices encapsulated with the dispersed silicone rubber‐modified epoxy molding compounds have exhibited excellent resistance to the thermal shock cycling test and have resulted in an extended device use life.
The effect of the processing steps on the oxidative stability of polyethylene tubing crosslinked by irradiation
Authors: Iring M. , Fodor Z. , Bődy M. , Baranovics P. , Kelen T. , Tüdős F. 
Published: April 2003

AbstractSome chemical and mechanical properties of intermediate products obtained in the production of PE heat‐shrinkable tubes were studied at different compositions of the material containing PE, antioxidant (aromatic amime or phenol) and, in some cases, flame retardant and/or an elastomer.In the course of the production phase, the thermooxidative stability decreases compared to that of compounded granulate. The greatest decrease is caused by irradiation. The aromatic amine seems to be a more effective antioxidant at similar compositions than the phenol derivative, and it shows a better resistance against irradiation. The oxidative stability of the finished shrinkable tubes is not affected by the quality of commercial granulate (initial polyethylene).Mechanical properties change slightly upon ageing, and the introduction of the elastomer did not alter the tensile strength and elongation at break. The remaining stability of the end product was still high enough to bear the stress of shrinking in use, and the good tensile strength of the material did not decrease upon thermal ageing either.In the extrusion of the granulated compound no significant change in the distribution and average molecular weight took place. Irradiation produced more than 50% insoluble fraction and the thermooxidative properties of the crosslinked sample changed significantly compared to the original PE and to the compound prepared from it.
Preparation of multiphase block copolymers by redox polymerization process, 4. Polymerization of methyl methacrylate by the redox system Mn(III)‐poly(ethylene glycol) containing azo groups
Authors: Cakmak Ismail 
Published: April 2003

AbstractRedox polymerization of methyl methacrylate using Mn(III) with poly(ethylene glycol) having azo and hydroxy functions was carried out to yield ethylene glycolmethyl methacrylate block copolymers with labile azo linkages in the main chain. These prepolymers were used to initiate free‐radical polymerization of styrene through thermal decomposition of the azo groups, resulting in the formation of multiblock copolymers. Successful blocking has been confirmed by fractional precipitation, a strong change in the molecular weight, and spectral measurements.
Benzylcellulose als thermoplastischer kunststoff, II. Stabilisierung und weichmachung.
Authors: Braun D. , Bahlig K. H. 
Published: April 2003

AbstractDurch Zusatz eines Stabilisators (4‐Benzyloxyphenol) kann die oxidative thermische Schädigung von Benzylcellulose bei deren Verarbeitung aus der Schmelze vermindert werden. Die notwendige Mindestkonzentration an Stabilisator beträgt 5 Gew.‐%. Durch äßere Weichmachung mit Diethylphthalat können die Glas‐ und die Verarbeitungstemperatur herabgesetzt und eine zufriedenstellende Weichheit und Flexibilität der ansonsten hart‐spröden reinen Benzylcellulose erzielt werden. Die erforderliche Weichmacherkonzentration liegt bei 5 bis 10 Gew.‐% und ist damit wesentlich niedriger als für andere Cellulosederivate wie z. B. Ethylcellulose (10–20 Gew.‐%) oder Celluloseacetate (20–30 Gew.‐%).
Thermogravimetrie als brennbarkeitsbestimmungs‐methode für lineare polyurethane
Authors: Pielichowski Krzysztof , Pielichowski Jan , Altenburg Horst , Wiegmann Marc 
Published: April 2003

AbstractIn der vorliegenden Arbeit wurden für eine Serie von Polyurethanen auf der Basis von Diol und Isocyanat der Sauerstoffindex (SI) gemessen und die thermische Zersetzung mittels thermogravimetrischer Analyse (TG) untersucht. Dabei wurde ein Zusammenhang zwischen einigen Parametern der thermischen Zersetzung und den SI‐Werten gefunden. Die Auswertung der experimentellen Ergebnisse zeigte, daß die Höhe des Massenverlustes bei 250°C und die SI‐Werte direkt proportional zueinander sind. Derselbe Zusammenhang besteht auch zwischen dem Logarithmus der Temperatur bei der maximalen Zersetzungsgeschwindigkeit und den SI‐Werten.
Studies on thermal stability of modified polycarboxylate cements
Authors: Bansal R. K. , Tewari U. S. , Singh P. , Murthy D. V. S. 
Published: April 2003

AbstractDental cement compositions made by mixing poly(acrylic acid‐co‐acrylamide) and mixtures of zinc oxide and cryolite (Na3AIF6) in various proportions of 10–50 wt.‐% (w/w) were cured at room temperature. From thermogravimetric analyses of the samples, the integral procedural decomposition temperatures (IPDT), maximum decomposition temperatures, activation energies and frequency factors were evaluated. The cured cement sample containing 20 wt.‐% cryolite in the filler mixture is thermally very stable.
Synthesis and polymerization of hydrophobic iodine‐containing methacrylates
Authors: Moszner Norbert , Salz Ulrich , Klester Alfred Michael , Rheinberger Volker 
Published: April 2003

AbstractStarting from 2,4,6‐triiodophenol, 2,3,5‐triiodobenzoic acid and 3,5‐bis(acetylamino)‐2,4,6‐triiodobenzoic acid, polymerizable methacrylates were synthesized and characterized by elemental analyses, IR, 1H‐NMR and 13C‐NMR spectroscopy. The iodine‐containing methacrylates show a different radical polymerization behaviour. 2,4,6‐Triiodophenyl methacrylate gives only oligomeric products in the presence of azoisobutyronitrile (AIBN), whereas 2‐methacryloyloxyethyl 2,3,5‐triiodobenzoate yields polymers. On the basis of mixtures of isomeric 1,3‐dimethacryloyloxy‐2‐ and 1,2‐dimethacryloyloxy‐3‐(2,3,5‐triiodobenzoyloxy)propane with usual crosslinking monomers, radiopaque materials were prepared.
Peroxid‐induzierte thioladdition an polybutadien
Authors: Gorski Ute , Klemm Elisabeth 
Published: April 2003

AbstractDie radikalische Addition von 1‐Octanthiol oder 3‐(Trimethoxysily)‐1‐propanthiol an die 1,2‐ bzw. 1,4‐cis‐Doppelbindungen des Polybutadiens erfolgt redox‐induziert mit Dibenzoylperoxid (DBPO) bei Raumtemperatur ohne nachweisbare Nebenreaktionen. Trans‐konfigurierte Doppelbindungen reagieren unter gleichen Bedingungen nicht. Die Molmassenverteilung der Additionsprodukte ist ähnlich eng wie die des reinen Polybutadiens.
Synthesis and characterization of water‐soluble diazonium salts as contrast‐enhancement materials
Authors: Liu Jui‐Hsiang , Her Chi‐Fon , Liu Hung‐Tsai , Chung Yi‐Chang 
Published: April 2003

AbstractWater soluble aromatic diazonium double salts, p‐diazodiphenylamine chloride zinc chloride (DZS‐1) and p‐diazoanisol chloride zinc chloride (DZS‐2), have been evaluated as photobleachable dyes for contrast enhancement lithography. After testing the bleaching characteristics, aqueous solutions of DZS‐1 and poly(vinyl alcohol) were used as a contrast enhancement material. Thermal stability, resist contrast, exposure parameters and other bleaching characteristics of the photobleachable membranes were investigated. A. commercial i‐line photoresist was used to evaluate the contrast ratio of the DZS‐1/PVA CEL layer. The contrast ratio obtained in this investigation is 1.67.
Antistatic modification of synthetic fibers by blend‐spinning of polymers containing zwitterionic antistatic modifiers and their copolymers
Authors: Sano Yoshiyuki , Saegusa Takeo , Kimura Yoshiharu 
Published: April 2003

AbstractNew poly(oxyethylene) derivatives (S‐betaine) having a zwitterionic structure of ammoniumsulfonate were prepared by the reaction of oxirane (EO) adducts of stearylamine with sodium chloromethanesulfonate and examined as blending antistatic modifiers for poly(ethylene terephthalate) (PET) and polyamide 6 (PA6) fibers. The blend PET and PA6 fibers containing 2.0 wt.‐% of S‐betaine exhibited a decreased half‐life time of leakage of electrostatic charge (t1/2) and a surface area resistivity (Rs) compared with those of the control PET and PA6 fibers. However, their antistatic properties were almost lost after repeated washings, because of the extraction of the agents. To increase the resistivity to washing, copolyester‐type modifiers comprising both S‐betaine and poly(ethylene glycol) were synthesized and incorporated into PET fibers. It was found that the antistatic properties of the blend PET fibers obtained can be retained even after dyeing and repeated washings.
Comparison of the coupling behaviour of diisocyanate and bisoxazolines in modification of liquid crystalline poly(ethylene terephthalate‐co‐oxybenzoate)s
Authors: Böhme Frank , Leistner Dirk , Baier Angela 
Published: April 2003

AbstractMethylene‐4,4′‐diphenyldiisocyanate and two different bisoxazolines were used for coupling reactions in carboxy‐terminated liquid crystalline poly(ethylene terephthalate‐co‐oxybenzoate). In order to guarantee defined conditions, copolyesters with different carboxylic group concentrations were synthesized. The determination of the carboxylic group content is described.The coupling behaviour of both types of chain extenders has been compared. It was evidenced that the bisoxazolines reacted significantly faster than the diisocyanate. A slight excess of bisoxazoline in the reaction mixture prevented thermomechanical degradation. Depending on the amount of coupling agent added, an oxazoline termination of the copolyester was observed. Additionally, probable crosslinking reactions and the thermal stability have been discussed.
Studies on the mechanical degradation of cellulose
Authors: Marx‐Figini Marianne , Figini Rubén Victor 
Published: April 2003

AbstractThe mechanical degradation by high‐speed stirring of cellulose in dilute n‐butanol suspensions was investigated on six different samples with degrees of polymerization (DP) between 300 and 7500. The degrees of polymerization were determined viscosimetrically in CuEn (copper ethylendiamine complex) at different times of mechanical action. The distributions of the DP were measured on the polymer‐analogous nitrates by size exclusion chromatography (HPSEC) in THF.The investigations reveal that only high‐molecular‐weight cellulose undergoes degradation, whereas celluloses with a starting DP0 < 3000 remain undegraded. In the case of degradation the decrease of the DP with time is exponential, reaching a “limiting” DP (DP∞) of about 3200 which does not diminish further.The narrowing with degradation time of the distributions of DP of the degraded samples allows to assume that the bonds splitting by the action of mechanical forces are the so‐called “weak links” present in high‐molecular‐weight cellulose. The course of the nonuniformity U with decreasing DP, could be confirmed by mathematical derivation of the relationship between U and the degree of degradation DP0/DPt, considering the scission of only “weak links”.