bluuebunny/crossref_metadata_2025_split huggingface dataset:
Beitrag zur Aufklärung der Morphologie von segmentierten Polyurethanen
Authors: Foks Janina , Naumann Irene , Michler Georg H. 
Published: April 2003

AbstractVerschiedene Polyester‐Polyurethane mit einem Anteil der Hartsegmente von 22 bis 100 Gew.‐% wurden hinsichtlich ihrer übermolekularen Strukturen elektronenmikroskopisch analysiert. Hierzu wurden sowohl Kryodünnschnitte und Lösungsfilme mit der Höchstspannungs‐Elektronenmikroskopie als auch Abdruckfilme und chemisch kontrastierte Ultradünnschnitte mit der konventionellen Transmissions‐Elektronenmikroskopie untersucht. In allen Proben wurde eine vielschichtige Morphologie gefunden, die aus mindestens vier unterschiedlichen Anteilen oder Phasen besteht. Dazu gehören Sphärolithe mit zentralsymmetrischem Aufbau, Garben mit einer Fächerstruktur, Fibrillen, Lamellen sowie Domänenstrukturen. Mit abnehmendem Hartsegmentanteil treten deutliche Änderungen in der Ausbildung und in der Häufigkeit dieser Strukturen auf. Die Existenz der sog. Mikrodomänen wird in Verbindung mit der angewandten chemischen Kontrastiertechnik diskutiert.
Studies on polycarbonate‐viton GF blends
Authors: Choudhary Veena , Mehta Rakesh 
Published: April 2003

AbstractThe effect of addition of different amounts of Viton GF, a fluoroelastomer, on the properties of polycarbonate (PC) was investigated. A significant improvement in impact strength (ca. 100%) was observed on addition of 20 wt.‐% of Viton GF. Thermal and dynamic mechanical behaviour of the blends was also investigated.The morphology of these blends was studied by scanning electron microscopy which revealed an uniform distribution of rubber cavities in polycarbonate matrix. The number of rubber cavities increased with increase of rubber content. Erosive wear studies were carried out on compression moulded sheets of PC and PC/Viton GF blends using a sand blasting rig. The effect of impact angle and the amount of abrasive used on the erosive behaviour was investigated. Polycarbonate showed a maximum erosion at an impact angle of 30°. A reduction in specific erosion was observed with increasing concentration of elastomer in the blends.
Synthesis and studies of ultraviolet light absorbing resins
Authors: Menon Susha R. , Patel Chetan G. , Parmar Jayant S. 
Published: April 2003

AbstractUltraviolet absorbers were prepared by condensation of 2‐hydroxy‐4‐methoxy benzophenone with formaldehyde using p‐toluene sulfonic acid as catalyst. For comparative study 2,4‐dihydroxy benzophenone was also condensed with formaldehyde under similar conditions. These resins were characterized by determining their molecular weights by non‐aqueous conductometric titration and vapour pressure osmometry, the structural features by IR and NMR study, the thermal properties by TGA, and the range of UV‐absorbance from UV‐spectra.
Synthesis and characterization of poly(isopropyl methacrylate‐co‐acrylamide)
Authors: Srinivasulu B. , Rao P. R. , Sundaram E. V. 
Published: April 2003

AbstractFree radical copolymerization of isopropyl methacrylate (IPMA) and acrylamide (AA) was carried out in the presence of 2,2′‐azoisobutyronitrile in dimethyl formamide at 60°C. The copolymer compositions were established by elemental analysis. The copolymerization reactivity ratios were determined by both Fineman‐Ross (F‐R) and Kelen‐Tüdős (K‐T) methods. The copolymers were characterized by IR, 1H‐NMR, thermal and dielectric studies. Glass transition temperature values (Tg) have been determined by DSC.
Effect of reactive diluents on curing behaviour and thermal stability of urethane methacrylate
Authors: Tyagi A. K. , Choudhary V. , Varma I. K. 
Published: April 2003

AbstractUrethane methacrylate monomer (UMA) containing methacryloyl group was prepared from toluylene diisocyanate (TDI), 2‐hydroxyethyl methacrylate (HEMA), and ethylene glycol by a two step reaction. Curing was investigated using benzoyl peroxide and N,N‐dimethylaniline as initiator system. The effect of concentration of initiator and reactive diluents, i.e., methyl methacrylate and styrene, on gel point was determined. An increase in gel time was observed by increasing the concentration of reactive diluent or decreasing the concentration of initiator. In TG traces (recorded in nitrogen atmosphere) of cured resins two step decomposition was observed in the temperature range of 230 to 500°C. The thermal stability of copolymers was influenced by the nature and content of reactive diluent.
Natural weathering of polyolefins. Kinetics of the photooxidation
Authors: Severini Febo , Gallo Raffaele , Ipsale Salvatore 
Published: April 2003

AbstractThe rate constants of the natural degradation processes of low density polyethylene and polypropylene films have been calculated on the basis of the molecular weights of weathered samples. Moreover, the optical densities, obtained by means of IR spectroscopy, indicate that the formations of carbonyl and vinyl groups are zero‐order reactions.
Hydrophobic recovery and misting behavior of plasma treated PS and PC surfaces
Authors: Morra M. , Occhiello E. , Garbassi F. 
Published: April 2003

AbstractOxygen plasma treatments of transparent polymers such as polystyrene (PS) and polycarbonate (PC) were performed. Then the hydrophobic recovery of treated surfaces and its effect on their misting behavior was studied. Surface investigations, such as XPS and water contact angle measurements, were combined with the characterization of misting behavior by light transmission methods.In the case of PS it was found that the composition and wettability of the surface layer is insensitive to extraction in water. Hydrophobic recovery leads to decreases of advancing angles upon aging by a mechanism involving macromolecular motions. Misting follows rather closely the behavior of water advancing angles.Oxygen plasma treatment of PC surfaces induces the formation of low molecular weight species which can be extracted by water. Both non‐extracted and extracted surfaces were found to undergo hydrophobic recovery with the same mechanism observed in the case of PS. In both cases the misting behavior can be well explained on the basis of wettability.
Untersuchungen zum Einsatz von technischen Kohlenwasserstofffraktionen als Monomerquelle und Lösungsmittel für die Dienpolymerisation
Authors: Gebauer Ulrich , Reiche Frank , Gehrke Klaus 
Published: April 2003

AbstractEs werden Untersuchungen zur Herstellung von modifiziertem cis‐1,4‐Polybutadien vorgestellt. Mittels Copolymerisation von Butadien mit Bestandteilen einer C5+‐Pyrolysefraktion, vornehmlich dem Isopren, sollte eine Modifizierung im Eigenschaftsbild des Polybutadiens angestrebt werden. Zur Polymerisation eingesetzt wurden das Ziegler‐Natta‐Katalysatorsystem Nickel(II)ethylhexanoat/Titantetrachlorid/Aluminiumtriethyl sowie das Lösungsmittel Toluol.In Vorbereitung der angestrebten Copolymerisation wurde mit dem genannten Katalysatorsystem die Polymerisierbarkeit von Bestandteilen der C5+‐Fraktion ausgetestet. Ziel dieser Untersuchungen waren eine Optimierung der Polymerisation auf höhere Ausbeuten an Polymeren über eine Variation der Konzentration der Katalysatorbestandteile und die Bestimmung der Zusammensetzung der Polymeren.Die Copolymerisationen des Butadiens mit Bestandteilen der C5+‐Fraktion wurden mit dem Ni/Ti/Al‐Katalysatorsystem bei zwei verschiedenen Konzentrationsverhältnissen der Katalysatorkomponenten durchgeführt. Über eine Bestimmung der Restmonomerzusammensetzung mittels Kapillar‐Gaschromatographie konnten Angaben zur Zusammensetzung der Copolymerisate hinsichtlich der wichtigsten Bestandteile erhalten werden.
Composites of silane treated cellulosic fibers and high density polyethylene
Authors: Raj R. G. , Kokta B. V. 
Published: April 2003

AbstractSilanes with different functional groups (vinyl, acryl and amino) were used to pretreat the wood fiber. Composites were made with high density polyethylene (HDPE) and silane pretreated wood fibers at various filler levels (0 to 40 wt.‐%). The effects of silane treatment on fiber‐matrix adhesion and fiber dispersion were studied. The characterization of fiber‐matrix interaction was done by IR. The influence of silane concentration, filler content and the nature of wood fiber on mechanical properties (tensile and impact strength) of the composites were examined.
The application of DSC in identification of LDPE/LLDPE blends mulching film
Authors: Wu Xiaobing , Chen Jiaqi , Zeng Xingrong 
Published: April 2003

AbstractThe mulching film samples of known and unknown composition LDPE/LLDPE blends have been analysed and the film samples of unknown composition have been identified by means of differential scanning calorimetry (DSC). The relationships between composition of film samples and melting enthalpy peak in their DSC thermograms have been discussed. The working curve for determining the composition has been given. The experimental results show that DSC is a quick, effective and accurate method for the analysis of main composition of LDPE/LLDPE blends mulching films.
The effect of PP and EPR grafted with acrylic acid on the properties and phase structure of polypropylene/elastomer/short glass fibre composites
Authors: Kelnar Ivan 
Published: April 2003

AbstractComposites comprising polypropylene/elastomer/short glass fibre in which acrylated polypropylene (AcPP) or acrylated ethylene‐propylene elastomer (AcEPR) were used to raise the interfacial adhesion were investigated. These agents cause a change in mechanical properties, and predominantly a rise in strength, not only due to an improved matrix‐fibre adhesion, but also by affecting the phase structure of the matrix in the surroundings of the fibres. Better results were obtained in the case of AcPP, but—surprisingly enough—the impact strength was lower with AcEPR than with a composite containing unfunctionalized components.
Lichtinduzierte Polymer‐ und Polymerisationsreaktionen, 47. Photopolymersysteme mit α‐sulfonyldesoxybenzoinen als initiatoren
Authors: Timpe Hans‐Joachim , Müller Uwe , Möckel Peter 
Published: April 2003

Abstractα‐Sulfonyl deoxybenzoines are formed by the reaction of desylchloride with sodium arylsulfinates in good preparative yields. The photolysis of these compounds proceeds with quantum yields of about Φin = 0.50. Compared to other photoinitiators, α‐sulfonyl deoxybenzoines polymerize methylmethacrylate in acetonitrile solution with moderate polymerization quantum yields only. On the contrary, the yellowing of cured polyester resins using these compounds as photoinitiators is much smaller.
Soluble maleimide prepolymers containing 1,3,5‐triazine groups as composite resin matrices. Synthesis, characterization, and evaluation
Authors: Dolui Swapan K. 
Published: April 2003

AbstractLow molecular weight amine‐terminated monomaleimide prepolymers containing 1,3,5‐triazine groups as well as ether linkages were synthesized by reacting benzophenone tetracarboxylic dianhydride, diamines having 1,3,5‐triazine group and maleic anhydride. These reactive prepolymers are soluble in low boiling solvents such as chloroform, tetrahydrofuran etc. They were characterized by elemental analyses, IR and NMR spectroscopy, vapour pressure osmometry, and viscosity. On heating at 180–190°C these prepolymers undergo simultaneous chain extension by Michael addition reaction and crosslinking by mutual reaction between their amine‐terminated and maleimide‐terminated ends. The cured polymers are thermostable and the thermal behaviour was studied by TGA, DTA, and isothermal aging. Laminates fabricated using these prepolymers and carbon fiber as reinforcing agent were evaluated by their flexural strength and interlaminar shear strength.
Studies on new non‐shrinking, thermally stable araldite‐type photopolymers with pendent arylacryloyl‐groups. I. Photoreaction of some aryl acrylic‐acid methyl esters in solution
Authors: Müller Harald , Nuyken Oskar 
Published: April 2003

AbstractAryl acrylic acids, e. g. furyl acrylic acid or thienyl acrylic acid are readily formed by the Knoevenagel condensation reaction of arylcarbaldehydes and malonic acid in pyridine. Esterification of these acids with methanol/sulfuric acid gives the corresponding aryl acrylic acid methyl esters in good yields. In methanolic solution these methyl esters isomerize upon irradiation (λ 280 nm). No photodimerization was observed. Kinetic data are given.
Antioxidants and stabilizers, CXIII. Oxidation products of the antidegradant ethoxyquin
Authors: Taimr Luděk , Prusíková Miluše , Pospíšil Jan 
Published: April 2003

AbstractIn connection with the study of the mechanism of antioxidant action of 6‐ethoxy‐2,2,4‐trimethyl‐1,2‐dihydroquinoline (ethoxyquin, I) and of its ecological responses in stabilized polymers we studied its oxidation with some selected agents and the properties of products thus obtained. The oxidation of I with silver oxide or lead dioxide proceeds by two main routes. One of them leads to 8‐(6‐ethoxy‐2,2,4‐trimethyl‐1,2‐dihydro‐1‐quinolinyl)‐6‐ethoxy‐2,2,4‐trimethyl‐1,2‐dihydroquinoline (IV), which is further oxidized to the blue compound 8‐(6‐ethoxy‐2,2,4‐trimethyl‐1,2‐dihydro‐1‐quinolinyl)‐2,2,4‐trimethyl‐6‐quinolone (IX). In the second route position 6 is attacked and 2,2,4‐trimethyl‐6‐quinolone (VII) is formed, which is stable under the conditions used, but is oxidized further with m‐chloroperbenzoic acid, giving rise to 2,2,4‐trimethyl‐6‐quinolone‐N‐oxide (VIII). The oxidation of ethoxyquin with potassium permanganate also gives rise to dimer IV and not to 1,1′‐bis(6‐ethoxy‐2,2,4‐trimethyl‐1,2‐dihydroquinoline) (III) reported in the literature. Potassium nitrosodisulfonate oxidizes I with formation of 6‐ethoxy‐2,2,4‐trimethyl‐8‐quinolone (X). The oxidation of ethoxyquin with m‐chloroperbenzoic acid gives rise to 6‐ethoxy‐2,2,4‐trimethyl‐1,2‐dihydroquinoline‐N‐oxide (V) and dimer IV. Nitroxide V was obtained in the crystalline state. In the presence of acids, and particularly on the surface of silica gel it decomposes to ethoxyquin and nitrone VIII. Nitroxide V is readily reduced to the starting ethoxyquin. The transitionally formed 6‐ethoxy‐1‐hydroxy‐2,2,4‐trimethyl‐1,2‐dihydroquinoline (XIV) readily disproportionates to I and V.
Matériaux composites à base de bois rétifié, III. Etude de l'influence de la granulométrie des charges lignocellulosiques
Authors: Revenu P. , Guyonnet R. , Bourgois J. 
Published: April 2003

AbstractDivers matériaux composites à base de peuplier rétifié ou naturel et de résine polyester insaturée ont été préparés par moulage. L'influence de la granulométrie de la charge a été étudiée sur quelques propriétés physico‐chimiques (densité, reprise d'humidité, dureté) ou mécaniques des matériaux obtenus. La densité et la reprise de masse en milieu humide sont toujours plus faibles si la charge est traitée thermiquement sous atmosphère inerte. Par contre, la dureté des composites issus du peuplier naturel est plus importante. Les propriétés mécaniques sont inférieures si la charge est rétifitée.Si la charge lignocellulosique est traitée thermiquement, il est possible d'optimiser les trois paramètres: densité, reprise d'eau et propriétés mécaniques; la granulométrie optimale du peuplier est ainsi comprise entre 0,75 et 1,5 mm.Les résultats obtenus sont expliqués en tenant compte des propriétés physico‐chimiques des charges et des interactions existant entre la résine polaire et le bois.
Phosphination of styrene‐bromostyrene‐divinylbenzene terpolymers
Authors: Bacquet M. , Le Maguer D. , Caze C. 
Published: April 2003

AbstractThe phosphination of styrene‐bromostyrene‐divinylbenzene terpolymers as a function of their textural and chemical characteristics has been studied. A small decrease of both specific area and porous volume with phosphination was observed. Chemical analysis showed the presence of side reactions like reduction of the halogen, addition on the double bond, and crosslinking reaction involving the different functional groups. The phosphorous distribution was inhomogeneous; this was attributed to a difference of crosslinking density in the beads due to the particular morphology of this type of support.
Creep studies of casein films grafted with acrylonitrile and n‐butyl methacrylate
Authors: Somanathan N. , Usha R. , Ranganathan T. S. , Sanjeevi R. 
Published: April 2003

AbstractCasein was grafted with a binary mixture of acrylonitrile and n‐butyl methacrylate and cast into films. The creep behaviour of the films was studied at different temperatures and at various applied stress levels. The extension increases with the increase of applied stress at all temperature.
Grafting reaction of methylmethacrylate onto EPR and EPDM rubbers. Toughening effects of graft copolymers on polycarbonate and poly(methylmethacrylate)
Authors: Severini Febo , Pegoraro Mario , Di Landro Luca 
Published: April 2003

AbstractThe grafting reaction of methylmethacrylate was done using EPR or EPDM rubbers swollen by a minimum amount of cyclohexane in the presence of benzoyl peroxide or azoisobutyronitrile and of the monomer at 80°C. The yield of the grafting reaction was evaluated as function of the added initiator and of the unsaturation content in the rubber. The products of the grafting reaction were used to obtain blends with poly(methylmethacrylate) and with polycarbonate. The mechanical properties indicate that a good toughening effect is obtained even if molding is done by simple compression technique.
Determination of micropore concentration and size distribution in carbon fibres by the saxs method
Authors: Włochowicz Andrzej , Rabiej Stanisław 
Published: April 2003

AbstractThe parameters of pores in carbon fibers made from poly(acrylonitrile), such as the volume fraction of pores, the correlation length, the specific surface area etc. were determined by SAXS. The pore size distribution functions were evaluated using the methods of Glatter and Jellinek.
Mehrphasensysteme auf basis von fluorpolymeren, 1. Modifizierung von füllstoffoberflächen
Authors: Schmidt E. , Schäfer E. , Semjonow V. , Brandrup J. 
Published: April 2003

AbstractIn Mehrphasensystemen aus Poly(tetrafluorethylen) (PTFE) und Glasfasern besteht praktisch keine Haftung zwischen Matrix und Füllstoff. Es wurde der Frage nachgegangen, ob es Wege zur Verbesserung der Grenzflächenhaftfestigkeit gibt und ob diese Verbesserungen ausreichen, eine Verstärkung, d. h. Anhebung der Reißfestigkeit bei gleichzeitigem Rückgang der Dehnung des Gesamtsystems zu erzielen.In diesem ersten Teil wird den theoretischen Voraussetzungen und der Modifizierung der Füllstoffoberflächen mittels Dispersionsbeschichtungen sowie Plasmaätzen und Plasmapolymerisation nachgegangen.In einem zweiten Teil werden Möglichkeiten zur Verbesserung der Grenzflächenhaftung durch Modifizierung der Polymer‐Oberfläche und durch Additive untersucht.
Mehrphasensysteme auf basis von fluorpolymeren, 2. Modifizierung der polymermatrix
Authors: Schmidt E. , Schäfer E. , Semjonow V. , Brandrup J. 
Published: April 2003

AbstractIn Mehrphasensystemen aus Poly(tetrafluorethylen) (PTFE) und Glasfasern besteht praktisch keine Haftung zwischen Matrix und Füllstoff.Es wurde die Frage untersucht, ob es Methoden gibt, diese Grenzflächenhaftung zu erhöhen und welchen Einfluß diese Erhöhung auf die Eigenschaften des Verbundsystems hat.In dem hier vorliegenden Teil 2 wird speziell auf den Einfluß der Modifizierung der Polymeroberfläche und des Zusatzes von Additiven eingegangen.
Dependence of properties of aqueous resols upon conditions of synthesis
Authors: Rubeš Miroslav , Eichler Josef 
Published: April 2003

AbstractPhenol formaldehyde resins of resol type were prepared under molar ratio phenol: formaldehyde: calcium hydroxide 1:2.7:0.1. The reaction products contained in all cases about 3.8% free formaldehyde and 1.5% free phenol. A 36% solution of formaldehyde was used for synthesis. The course of synthesis, expressed by drop of free formaldehyde contents in the reaction mixture, is presented. In aqueous resol solutions, prepared by this way, the decrease of miscibility with water was examined during storage at 10°C. It was found that the resol synthesized at lower temperature had better shelf life than that prepared at higher temperature. The presented results are of practical importance in the cases where compatibility with water is a significant processing parameter.
Nucleophilic substitution reaction of ethanolamine onto poly(phenyl acrylate) and substituted poly(phenyl acrylate)s
Authors: Baskaran D. , Rajalingam P. , Radhakrishnan G. 
Published: April 2003

AbstractThe nucleophilic substitution reaction of differently substituted phenoxy groups with ethanolamine in various poly(phenyl acrylate)s was investigated in dioxane at 60, 80, and 100°C. The conversion, as determined from IR‐ and 1H‐NMR spectroscopy and elemental analysis, depends on the temperature and the kind of substituents at the phenyl ring.
Studies on new non‐shrinking, thermally stable araldite‐type photopolymers with pendent aryl acryloyl‐groups. II. Photoreaction of some arylacrylic‐acid methyl esters in the liquid state
Authors: Müller Harald , Nuyken Oskar 
Published: April 2003

AbstractLiquid aryl acrylic acid methyl esters, e.g. furan acrylic acid methyl ester and thienyl acrylic acid methyl ester, were UV‐irradiated (λ ≥ 280 nm) at a temperature of 2°C above their melting points. IR‐methods were used in order to monitor the photoreactions which are of a second order kinetics. The application of GC‐MS indicated that dimers, trimers and tetramers, but no polymers were formed under the chosen conditions.
Einfluß der Herstellungsbedingungen auf die Eigenschaften von Precursor‐Polyacrylnitrilfasern und daraus erzeugten Kohlenstoffasern
Authors: Mikołajczyk Teresa , Kamecka‐Jedrzejczak Katarzyna , Krucińska Isabella 
Published: April 2003

AbstractC‐Fasern sind wegen ihrer herausragenden Festigkeit und ihres hohen Moduls für die verschiedensten technischen Einsatzgebiete von großer Bedeutung. Deshalb werden viele Anstrengungen unternommen, Fehlstellen in den Fasern, die die Eigenschaften praktisch begrenzen, zu minimieren. Eine deutliche Hilfe hierbei ist die Optimierung der Struktur der PAN‐Fasern, die zu C‐Fasern weiterverarbeitet werden. In der vorliegenden Arbeit wird für naßgesponnene PAN‐Fasern beschrieben, wie es durch Aufteilung der Verstreckung und angemessene Temperaturführung gelingt, Faser‐Strukturen einzustellen, die zu besseren C‐Faser‐Eigenschaften führen. Die praktischen Ergebnisse werden durch Strukturanalysen belegt.