bluuebunny/crossref_metadata_2025 huggingface dataset:
Telechele als bausteine für neuartige polymere
Authors: Heitz Walter
Published: April 2003

The developments in the syntheses of α,ω‐bifunctional oligomers (telechelics) are revued. Telechelic soft segments are synthesized by cationic, anionic and radical polymerization of vinyl and heterocyclic monomers. Telechelic PTHF obtained with CH3CO+/Ac2O stems from an equilibrating process and not from a transfer reaction. Telechelic polyisobutene is formed by the inifer technique of Kennedy. The use of lithium initiators with protected functional groups in butadien polymerization results in products with high 1.4‐content. The group transfer polymerisation is specially suited to prepare telechelic PMMA of narrow molecular weight distribution. The “dead end” polymerisation is a necessary condition to obtain a functionality of two by radical polymerization. The synthesis of telechelic hard segments of the PPO and PPS type is described.
Telechele des methylpropens durch kationische polymerisation
Authors: Freyer Christian V. , Mühlbauer Hans‐Peter , Nuyken Oskar
Published: April 2003

Aromatic and aliphatic hydrocarbons containing isopropyl chloride end groups in combination with boron trichloride are effective initiator systems for the cationic polymerization of methyl propene. The mathematical modelling of the proposed reaction mechanism leads to rate constants for initiation, propagation and termination which allows a good fit with experimental results. Recycling experiments have clearly shown that it is possible to reuse the coinitiator boron trichloride and the solvent dichloromethane without effecting the quality of the products.
Amphiphile polymere mit blockstruktur herstellung über makromonomere und eigenschaften
Authors: Albrecht Klaus , Wunderlich Winfried
Published: April 2003

The radical polymerization of methylmethacrylate (MMA) in the presence of a hydroxyl‐functional chain transfer agent (2‐mercaptoethanol) followed by reaction with 2‐isocyanatoethylmethacrylate (IEM) yielded macromonomers with molecular weights in the range of 6,5 · 103 to 23,2 · 103. Homopolymerization of the latter gave highly compact molecules which showed a solution behaviour like linear PMMA of MW = 55 000 but having a real molecular weight of 1,02 · 106. Copolymerization with methacrylic acid delivered comb‐like amphiphilic graftcopolymers with a yield of 89 %.
Alternierende copolymerisation mit lewissäuren. Copolymerisation von p‐chlorstyrol und n‐butylmethacrylat mit ethylaluminiumsesquichlorid
Authors: Braun D. , Manger E.
Published: April 2003

Nach einem Überblick über die alternierende Copolymerisation mit Lewissäuren wird die Copolymerisation von p‐Chlorstyrol und n‐Butylmethacrylat mit Ethylaluminiumsesquichlorid in Toluol untersucht (Copolymerisationsdiagramm, Zusammensetzung der Copolymeren als Funktion des Umsatzes und der Polymerisationstemperatur, Abhängigkeit der Grenzviskositäten von der Polymerisationszeit, Zeit‐Umsatz‐Diagramm). Das 1H‐NMR‐Spektrum eines annähernd äquimolaren Copolymeren bestätigt die alternierende Struktur und schließt die Möglichkeit einer Mischung aus äquimolaren Co‐ und Homopolymeren aus.
Stereoselektive polymerisation von olefinen mit homogenen, chiralen ziegler‐natta‐katalysatoren
Authors: Kaminsky Walter
Published: April 2003

Performing polymerizations of propylene with the stereorigid chiral ethylene(bisindenyl)zirconiumdichloride or the corresponding tetrahydroindenyl compound as transition metal components in combination with methylaluminoxane yields lightly isotactic polypropylene. Polymerization activity reaches values of more than 40 metric tonnes polypropylene per mol zirconium and hour. Polymers produced in this way display characteristical features. The mean molecular weight distribution Mw/Mn lies between 1.9 and 3 which is rather narrow. The toluene soluble(atactic) amount is less than 0.2 weight% and the 13C‐nmr spectroseopically determined isotactic sequence lengths are between 60 and 120 propene units.

Polymerizations may also be run in a bubble column. In a similar manner long chain α‐olefines, such as 1‐butene, isobutene and 4‐methylpentene can be polymerized with the help of these chiral catalysts into isotactic crystalline macromolecules.
Hydrierter nitrilkautschuk ein werkstoff mit neuen eigenschaften
Authors: Obrecht Werner , Buding Hartmuth , Eisele Ulrich , Szentivanyi Zsolt , Thörmer Joachim
Published: April 2003

Durch selektive Hydrierung der Doppelbindungen von Nitrilkautschuk (NBR) erhält man Produkte, die formal aus Ethen, 1‐Buten und Acrylnitril aufgebaut sind. Chemische und physikalische Unterschiede zwischen dem Ausgangs‐ und Endprodukt werden durch die spezifischen Eigenschaften von 1,4‐verknüpften Butadien‐ und den daraus abgeleiteten Ethensequenzen erklärt. Im Gegensatz zu Butadiensequenzen sind Ethensequenzen chemisch beständiger und können kristallisieren. Dies wird durch thermische und mechanisch‐dynamische Untersuchungen sowie die Bestimmung der Zugfestigkeit am Rohkautschuk und am rußgefüllten Vulkanisat gezeigt.
Conducting organic materials: Present status and scope
Authors: Wegner Gerhard
Published: April 2003

Electrically conducting polymers derived from linear chain insulating macromolecules are best described as ion‐radical salts of the backbone‐units. They are obtained from the parent polymer by oxidation or reduction; in some cases the conducting polymer is obtained by simultaneous polymerization and oxidation from the corresponding polymer directly. The so called electropolymerization of pyrrole is an example for the latter case. The stability and other properties of the conducting polymers as they are related to possible applications can be understood based on the structural informations on these salts of rather high reactivity with regard to redox‐reactions.
Kristalline und flüssigkristalline copolyester substituierter und unsubstituierter 4‐hydroxybenzoesären
Authors: Kricheldorf Hans R. , Conradi Arndt , Schwarz Gert
Published: April 2003

Three synthetic strategies were explored to lower the melting point of poly(4‐hydroxybenzoate) below 400°C. Binary copolyesters of 4‐hydroxybenzoic acid and 3‐substituted 4‐hydroxybenzoic acid were highly crystalline, regardless of composition, and did not melt below 400°C. In contrast ternary and quartenary copolyesters containing 3‐bromo‐4‐hydroxybenzoic acid may possess melting points below 360°C. Binary copolyesters of 4‐mercaptobenzoic acid and 3‐substituted 4‐hydroxybenzoic acids melt in the range of 360–400°C. Random copolyesters of 3‐(4‐hydrophenyl) propionic acid and 4‐hydroxybenzoic acid are mainly amorphous with glass‐transition temperatures between 50 and 15°C. They contain liquid‐crystalline domains, which in the case of the 1:1 copolyester are stable over a range of ca. 400°C. The heat‐distortion temperatures are low (60–80°C) due to the predominant influence of the amorphous matrix.
Nichtlineare optik. Grundlagen und eigenschaften organischer materialien
Authors: Schwoerer Markus
Published: April 2003

In der Optik von Huygens (1629–1695), Newton (1643–1727) und Fresnel (1788–1827)1 sind die optischen Eigenschaften der Materie unabhäangig von der Intensität des Lichts. In der nichtlinearen Optik werden die optischen Eigenschaften der Materie durch das Licht selbst dergestalt verändert, daß nach dem Abschalten des Lichts keine physikalischen oder chemischen Veränderungen in der Materie übrigbleiben. Insbesondere kann die Brechzahl in durch die Intensität I des Lichts verändert werden. Ebenso wichtig ist die Abhängigkeit der Polarisierbarkeit \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \alpha \limits_ \approx $\end{document}
von der elektrischen Feldstärke \documentclass{article}\pagestyle{empty}\begin{document}$ \overrightarrow {\rm E} $\end{document}
der Lichtwelle, sodaß das induzierte Dipolmoment \documentclass{article}\pagestyle{empty}\begin{document}$ \overrightarrow {\rm p} $\end{document}
und‐in nichtzentrosymmetrischen Körpern‐auch die Polarisation \documentclass{article}\pagestyle{empty}\begin{document}$ \overrightarrow {\rm P} $\end{document}
nicht mehr proportional zu \documentclass{article}\pagestyle{empty}\begin{document}$ \overrightarrow {\rm E} $\end{document}
sind. Damit können zahlreiche Phänomene erzeugt werden, die sowohl in ihren Grundlagen, als auch im ihere Anwendung faszinierend sind. Dazu gehören die Frequenzverdopplung, die optische Bistabilität und die Phasenkojugation. Mit Hilfe der optischen Bistabilität kann ein optisches Anologon zum Transistor‐ein Transphasor‐hergestellt werden, der Licht mit Licht ohne Umwege über elektrischen Strom schaltet. Mit Hilfe der Phasenkonjugation können vor allem verzerrungsfreie Bildübertragungen‐auch im Mikrometer‐Maßstab‐erreicht werden.
Polymers for audio and video equipment
Authors: Gossink R. G.
Published: April 2003

Polymers find widespread use in present‐day audio and video equipment. Their applications can be divided into: (i) polymers used for the outside of the equipment, (ii) polymers used for mounting, encapsulation or passivation of electronic devices, (iii) polymers for other stationary or moving parts, (iv) polymers used for audio and video data storage, and (v) photosensitive polymers that play a temporary role in the structuring of fine details.

In this paper, attention is focussed on transparent polymers (“optical plastics”) that are employed in projection television (PTV) and optical disc systems. First, the principles of these systems and the polymer properties they require are summarized, after which the polymers and technologies used in these applications are described. These polymers can be divided into two categories: (i) UV‐curable coatings on a substrate of a different nature, and (ii) transparent thermoplastics and thermosets.

Finally, some shortcomings of the currently available materials are mentioned.
Polymere in der drucktechnik
Authors: Vollmann Hansjörg , Fraß Werner , Mohr Dieter
Published: April 2003

Three main processes are used in the printing industry: Letterpress, Lithography and Gravure printing.

In the early fifties polymer coatings have been introduced in lithographic printing plates formulations. Later, similar systems have proved to be suitable for letterpress, and very recently for gravure printing layers, too.

Most polymer formulations used in printing techniques generally have the following features in common:

• They are light sensitive

• They are coated on to a flat substrate

• After imagewise exposure the more soluble areas of the coatings are removed in a development step.

The requirements for the polymers used in printing layers are as different as the characteristics of each individual printing process.

• The importance of the specific optical properties of the polymers is demonstrated discussing some negative acting light sensitive systems, amongst them the photopolymerisation of monomers.
Kinetik der VC‐polymerisation: Ein Modellvergleich, I. Modellselektion
Authors: Weickert Günter , Henschel Gerd , WeißEnborn Klaus‐Dieter
Published: April 2003

In der Vergangenheit wurde eine Vielzahl kinetischer Modelle zur quantitativen Beschreibung der Polymerisation von Vinylchlorid (VC) entwickelt, die dem Praktiker die Auswahl eines geeigneten Modells erschweren. Ein Vergleich der bisher in der Fachliteratur entwickelten Modellvorstellungen anhand einer großen Anzahl experimenteller Messungen, die unter Variation der Einflußgrößen Reaktionstemperatur, Initiatorart und ‐konzentration sowie der Dispergatorart und ‐konzentration (bei Suspensionspolymerisationen) erhalten wurde, erlaubt nicht nur die Beurteilung der Modellqualität, sondern führt auch zu einem praktikablen „optimalen”︁ Modell, dessen Vorteile an Beispielen nachgewiesen werden können.
Kinetik der VC‐polymerisation: Ein Modellvergleich, II. Anwendungsbeispiele
Authors: Weickert Günter , Henschel Gerd , Weißenborn Klaus‐Dieter
Published: April 2003

Durch Vergleich der bisher in der Fachliteratur entwickelten Modellvorstellungen zur Beschreibung der Polymerisationskinetik von Vinylchlorid (VC) bis zu hohen Monomerumsätzen wurde im Teil I dieser Arbeit1 ein Modell selektiert, das sich gut für die Auswertung experimenteller Daten aus Laboruntersuchungen sowie für die Beschreibung der Reaktionskinetik im Zusammenhang mit der modellhaften Beschreibung und Optimierung technischer Reaktoren eignet. In der vorliegenden Arbeit wird dies anhand einiger Beispiele nachgewiesen.
Identification of nylons by thin layer chromatography
Authors: Tsatsaroni Eforia G. , Kehayoglou Aristides H.
Published: April 2003

The composition of nylons by ω‐amino‐carboxylic acid monomers, dicarboxylic acids, and diamines is identified by thin layer chromatography, using their acid hydrolysates and determining the corresponding Rf values.
Interphase in polypropylene‐sepiolite composites based on dynamic mechanical analysis
Authors: Linares A. , Morales E. , Ojeda M. C. , Acosta J. L.
Published: April 2003

This paper describes the interphase between polypropylene and aldehyde surfacetreated sepiolite composites, following the method of Souma which determines a parameter based on dynamic measurements. The results obtained support the existence of a “soft” mesophase with good surface adhesion properties to the filler particle.
Methode zur Extraktion der niedermolekularen Anteile von PVC
Authors: Braun D. , Bezdadea E. , Dethloff M.
Published: April 2003

Es wurde eine neue Methode zur Abtrennung der niedermolekularen Anteile aus PVC entwickelt. Sie beruht auf einer Löseextraktion mit Chloroform und anschließend mit Tetrachlorkohlenstoff. Die extrahierten niedermolekularen Anteile wurden viskosimetrisch, gelpermeationschromatographisch und spektroskopisch (IR und NMR) analysiert. Es wurde festgestellt, daß sie sehr niedermolekular sind und viel mehr strukturelle Defekte als das Gesamt‐PVC enthalten. Die thermische Stabilität ist bis zu achtmal geringer als die von PVC. Die Entfernung dieser niedermolekularen Anteile aus PVC ermöglicht eine erhebliche Herabsetzung der notwendigen Stabilisatormenge.
Behaviour of regenerated polyethylene, recovered from worn out packaging, to artificial ageing and under natural climate conditions
Authors: Stoica Stela , Sebe Mircea‐Octavian , Constantinescu Elena
Published: April 2003

This paper presents the efficiency of styrenated phenol and dian (bisphenol A) stabilizers in high density polyethylene regenerated from worn out packaging samples, by following up the regenerates' behaviour under artificial ageing as well as in natural climate conditions.

The efficiency of the stabilizers was assessed by following up the characteristic physical‐mechanical modifications and the formation of carbonyl groups in the stabilized, regenerated polyethylene samples, as compared with the primary polyethylene and the unstabilized regenerated samples.
Pervaporation of water‐n‐propanol mixtures through membranes composed of poly(N‐vinylpyrrolidone)‐poly(methacrylic acid) complexes
Authors: Nieuwenhuis J. , Tan Y. Y. , van Ekenstein G. O. R. Alberda
Published: April 2003

Membranes composed of poly(vinylpyrrolidone)‐poly(methacrylic acid) (PVP‐PMAA) complexes appear to be suitable for pervaporation of water‐n‐propanol mixtures. The membranes are selective to water. The separation factor α increases with increasing content of propanol, wPrOH, and reaches a maximum value for wPrOH at about 0.8 in the case of PVP‐rich membranes, and close to wPrOH = 1 for PMAA‐rich membranes. All membranes exhibited maximum swelling at wPrOH of ca. 0.4.

At constant wPrOH of 0.8 the value of α changes in a complicated manner with the composition of the membrane. Under this condition of constant wPrOH, α runs parallel with the swelling degree. A tentative explanation is proposed for results pertaining to membranes containing not too high excesses of PVP or PMAA.
Synthesis and characterization of some 2,4′‐dibenzyldiisocyanate ionic polymers. II. Cationic polyurethances using N,N′‐bis‐(β‐hydroxyethyl)‐piperazine
Authors: Buruianǎ Tinca , Besltiuc I. , Caraculacu A.
Published: April 2003

Cationic polyurethanes containing piperazine rings on the macromolecular chain were synthesized. The polymers form flexible and transparent films. The behaviour of diluted solutions in solvents of different dielectrical constants was studied.
Solution properties of shellac, 4. Solubility parameter of shellac
Authors: Mishra Mahendra Kumar
Published: April 2003

The solubility parameter (δ) of shellac has been estimated from three dimensional approach and solubility map methods, and was found to be 11.3 cal1/2 cm−3/2. The maximum ultimate strength σmax of shellac has also been estimated.
The effect of various pigments on the rheological behaviour and morphology of polypropylene
Authors: Pei‐Ren Li
Published: April 2003

In this paper the characteristics of polypropylene (PP) containing pigments are systematically studied. The results show that the flow properties of PP melt, morphological structures, and drawing behaviour of the fibres are obviously affected by the presence of certain pigments dispersed in the PP matrix. The effects of various pigments added in PP display great difference. The flow resistance of PP increases with the addition of phthalocyanine blue, carbon black, and titanium dioxide, but decreases with the presence of BR red and GL orange. The extrudate swell effects of PP melt are intensified by adding these pigments. The yield stress of filaments with rod structure is 80–125% lower than that of filaments with spherulitic structure.
Propriétés de la Surface d'un Film de Polyéthylène Modifiée par Greffage d'un Oligomère Acrylique
Authors: Lavielle Lisette , Balard Henri
Published: April 2003

Le greffage d'un dérivé acrylique liquide (méthylène‐2 pentanedïoate‐1,5 de diéthyle) est effectué en présence de peroxyde de benzoyle à la surface d'un film de polyéthylène (HD). Les propriétés de mouillabilité de la surface sont examinées en relation avec les propriétés d'adhésion vis à vis de l'aluminium, et comparées avec celles d'un film de polyéthylène greffé dans la masse à l'acide acrylique. La mobilité des chaǐnes greffées à la surface pourrait ětre à l'origine des différences de comportement observées.
Thermal degradation studies of cellulose phosphates and cellulose thiophosphates
Authors: Kaur Baljinder , Gur Ishwar S. , Bhatnagar Hari L.
Published: April 2003

The thermal degradation of cellulose, cellulose phosphates, and cellulose thiophosphates was studied by differential thermal analysis, dynamic thermogravimetry, and derivative thermogravimetry from ambient temperature up to 750°C. Various thermodynamic parameters for different stages of thermal degradation of cellulose and its derivatives have been obtained following the methods of Broido, and Freeman and Carroll. Infrared spectra of thermally degraded samples were obtained. The data were analyzed in an effort to obtain more information concerning the flame‐retardant mechanisms of cellulose phosphates and cellulose thiophosphates. Lower values of decomposition temperatures and activation energies of decomposition and higher char yields of cellulose phosphates as compared to cellulose lead to the conclusion that cellulose phosphorus esters are good flame retardants, and this property is retained even when these esters were subjected to ion exchange by Na+ and K+ ions. However, with the introduction of sulphur atoms, there was some decrease in this property.
Die polymerisation von lactamen, 86. Verzweigung der autopolymerisationsprodukte von 8‐octanlactam
Authors: Prokopová Irena , Tuzar Zdeněk , Kondelíková Jaroslava , Králíček Jaroslav
Published: April 2003

Durch das Studium der Lösungseigenschaften des unter Bedingungen der Autopolymerisation im Temperaturbereich 240–260°C hergestellten Poly(8‐octanlactam) wurde die angenommene Verzweigung der Polymerketten bestätigt. Nach der Hydrazinolyse der Polymeren wurden in den Polymerketten Amidinstrukturen identifiziert, die jedoch für das Entstehen der Verzweigungszentren nicht im vollen Ausmaß verantwortlich sein können.
Synthesis and polymerization of new vinyl derivatives of thymine
Authors: Akashi Mitsuru , Tanaka Yasuo , Iwasaki Hiroaki , Miyauchi Noriyuki
Published: April 2003

N‐acryloyl and N‐methacryloyl derivatives of thymine were prepared by one‐step reaction of silylated thymine with acryloyl chloride and methacryloyl chloride, respectively, in good yields. These vinyl monomers containing thymines were polymerized and copolymerized with water soluble vinyl monomers such as acrylamide and vinylpyrrolidone by free‐radical polymerization. Complex formation between copolymers and RNA in aqueous solution was studied by means of UV spectroscopy.
Radiation initiated grafting on fluoro polymers III. Grafting of N‐vinylpyrrolidone in aqueous solution on poly(vinylidene fluoride) films by accelerated electrons
Authors: Niemöller Axel , Ellinghorst Guido
Published: April 2003

The radiation induced grafting of N‐vinylpyrrolidone in aqueous solution onto poly(vinylidene fluoride) (PVF2) films by preirradiation technique using 160 keV electrons has been investigated. Among the grafting parameters, the most important are storage time after irradiation, grafting time, grafting temperature, and absorbed dose. Trapped radicals in PVF2 are very stable; peroxy radicals generated by storage of irradiated samples in air can initiate grafting, too. The grafting of PVF2 proceeds slowly from the film surface to the inner part, ceasing when the middle of the film is reached from both sides. The penetration of the grafting front has been observed by “Differential‐Interference‐Contrast” (DIC)‐microscopy. At constant other parameters, the penetration depth depends on the grafting time and can be correlated with the time conversion curves. For the discussion of the grafting reaction a simple kinetic model has been developed. A very high activation energy of diffusion of ∼ 80 kJ mol−1 has been estimated both by sorption measurements and by application of the kinetic model with regard to the activation energies of grafting rate and saturation grafting yield (SGY). From the SGY‐dose relationship the ratio of the rate constants kpkt−1 has been calculated. As for other grafting systems this ratio has about the 105‐fold value in relation to homopolymerization of the same monomer. This indicates the restrained mobility of propagating macroradicals in the highly viscous grafting medium leading particularly to a lower kt in comparison with homopolymerization.
Tribasic lead sulphate as efficient curing agent for polychloroprene
Authors: Joseph R. , George K. E. , Francis D. Joseph
Published: April 2003

Tribasic lead sulphate is tried as a practical curing agent for polychloroprene. The cure characteristics of the compounds as well as the technical properties of the vulcanizates show that it can act as a potential curative.
Photoabbau von copolymeren aus styrol, methylmethacrylat und acrylnitril mit 2‐naphthylmethacrylat
Authors: Boudevska H. , Bratschkov Ch. , Todorova O. , Bezdadea E. , Braun D.
Published: April 2003

Copolymere aus Styrol, Methylmethacrylat und Acrylnitril mit steigenden Gehalten an 2‐Naphthylmethacrylat (2‐NMA) wurden photooxidativ abgebaut, um den Einfluß dieses Comonomeren als inneres Modifizierungsmittel beim Photoabbau dieser Polymeren untersuchen zu können. Es wurde festgestellt, daß 2‐Naphthylmethacrylat bei Gehalten bis zu 15 Gew.‐% in Copolymeren mit Styrol zu einer Stabilisierung führt. Auch im Falle der Copolymeren mit Acrylnitril bestätigte sich diese stabilisierende Wirkung des 2‐Naphthylmethacrylats. Bei den Copolymeren mit Methylmethacrylat kann der Einfluß des 2‐Naphthylmethacrylates wegen der Depolymerisierungstendenz der MMA‐Grundbausteine nicht eindeutig interpretiert werden, obwohl sich bei dem Photoabbau eines Copolymeren mit ca. 16 Gew.‐% 2‐NMA die Uneinheitlichkeit verringerte.
Composites von novolak‐lignit zur herstellung von aktivkohle
Authors: Simitzis Johannis
Published: April 2003

Novolak‐Harze, mit unterschiedlichen Anteilen an Lignit vermischt, wurden gehärtet und dann bis 1000°C verkohlt. Die während der Verkohlung entwichenen Gase CH4 und CO wurden gemessen, ebenso der Gewichtsverlust und das Schrumpfen der Proben. Es zeigte sich, daß zum thermischen Abbau der Proben mindestens 800°C notwendig sind. Die Porengrößenverteilung der Verkohlungsrückstände wurde bestimmt. Es wurde gefunden, daß das Verhältnis der Novolak‐Lignit Mischungen so gewählt werden kann, daß schließlich die kohlehaltigen Materialien denen gleichen, die nur aus Lignit Ausgangsmaterial (hauptsächlich Makroporen enthaltend) oder nur aus Novolak (hauptsächlich Übergangsporen enthaltend) hergestellt sind. Es zeigte sich auch, daß die hergestellten kohlehaltigen Materialien die Fähigkeit haben, Methylenblau aus seinen wäßrigen Lösungen zu adsorbieren.
Epoxy resins modified by carbon dioxide
Authors: Rokicki Gabriel , Lewandowski Marcin
Published: April 2003

The modification of epoxy resins by means of carbon dioxide is presented. The resulting resins contained different amounts of cyclic carbonates (1,3‐dioxolane‐2‐one rings) instead of a part of epoxy groups. The effect of the cyclic carbonate content on viscosity, gel time, peak exotherms, and crosslinking extent of the above mentioned resins was investigated.

Mechanical and thermomechanical properties of the modified resins cured with triethylenetetramine have been determined. It was found that heat‐distortion temperature, impact resistance, hardness, compressive strength, and lap shear strength of the resins containing cyclic carbonates were higher than those of unmodified ones.
N,N'‐Diglycidylimides and their polymers
Authors: Mantecóan Ana , Cádiz Virginia , Serra Angels , Martínez Pedro‐Alberto
Published: April 2003

At first new epoxy derivatives, namely glycidylimide compounds, have been prepared using benzyltrimethylammonium chloride as catalyst and epichlorohydrin in excess. Their chemical and physical properties were studied. Spectral data confirmed these new structures.

Afterwards new epoxy resins have been synthesized by the reaction of diimides and their glycidyl derivatives in N,N‐dimethylformamide. The physical characteristics of the obtained polymers and also their solubilities are reported.

Their IR, 1H‐ and 13C‐NMR spectra allowed to confirm the polymer structure. Thermal analysis of these compounds showed their good thermal properties.
Synthesis and properties of compounds related to stilbazole
Authors: Nethsinghe Lakshman P. , Plesch Peter H. , Hodge David J.
Published: April 2003

We report attempts to create conjugated polymers consisting of alternating phenylene and heterocyclic rings separated by double bonds by means of condensations between terephthalaldehyde and dimethyl nitrogen bases. Because the products precipitated during their formation even at 180°C in N‐methyl‐2‐pyrrolidinone (NMP), only oligomers of up to ca. 30 rings (DP = 15) could be obtained; most of the adequately soluble products had DP between 4 and 8, and from these oligomers films on glass or quartz could be made. When the films were exposed to I2, NO2, or SbF5, most of them, initially very good insulators, showed an increase in electrical conductivity of up to 6 powers of 10; but the rapid reversal of this change when the reagent evaporated and the lack of any clear changes in the UV‐vis spectrum of the films showed that most likely true “doping” had not occurred.

Extensive syntheses with a variety of quaternised bases also failed to yield oligomers oxidisable by electron‐acceptors.

For reference purposes, especially for their spectra, a large number of pure “model” compounds of the distyrylpyridine and distyrylpyrazine type, and quaternised analogues of the former, were synthesised, many of them new compounds. These were also used as calibrants for a GPC column operating with NMP solutions.

Several improvements were made in the synthetic techniques.
Influence des copolymères greffés sur les propriétés mécaniques des alliages de polyéthylène avec polystyrène
Authors: Boutevin Bernard , Piétrasanta Yves , Sarraf Tarek
Published: April 2003

Nous avons étudié l'utilisation des copolymères greffés polyéthylène‐graft‐poly‐styrène (P(E‐g‐S)) dont les mélanges de polyéthylène basse densité et polystyrène. Les copolymères P(E‐g‐S) sont préparés par la polymérisation du styrène en présence de polyéthylène hydroperoxydé. L'addition de 2,5% en poids de P(E‐g‐S) au mélange polyéthylène‐polystyène augmente considérablement leur contrainte à la rupture εR mais beaucoup moins leur allongement à la rupture εR. Une comparaison entre les copolymères greffés et séquencés utilisés comme des émulsifiants des mélanges polyéthylène‐polystyrène montre que le P(E‐g‐S) est intermédiaire entre les copolymères greffés et séquencés cités en ce qui concerne leur influence sur les propriétés mécaniques des mélanges. Les photographies de la surface de fractures des mélanges montrent la diminution de la taille de phase après addition du P(E‐g‐S) aux mélanges.
Photo‐oxydation d'elastomèeres EPDM et EPM en présence de systèmes photosensibles, 1. rôle des dérivés de phénylacétophénone
Authors: Bousquet Jean‐Alain , Fouassier Jean‐Pierre
Published: April 2003

La photo‐oxydation d'élastomères de type poly[éthylène‐co‐propène‐co‐(1,4‐hexadiène)] (EPDM) et de type poly(éthylène‐co‐propène) (EPM) photosensibilisés avec différents dérivés alcoxylés de phényl acétophénone: 2,3 diméthoxy (DMPA), 2‐méthoxy (MPA), 2‐éthoxy (EPA), à l'état de mélange a été étudiée dans le but de préciser la nature des mécanismes primaires de transfert d'énergie et d'amorçage radicalaire ainsi que le mode de développement des principales réactions d'oxydation dans un milieu hétérogène où les valeurs des rendements quantiques sont difficilement accessibles. Par analogie avec des systèmes modèles précédemment étudiés, l'importance du rôle joué par les fonctions hydroperoxydes et les photoproduits issus de la dégradation du photo‐amorceur, a été mise en valeur. La photoréticulation des échantillons irradiés apparaît faire partie intégrante du processus général de photooxydation dans lequel deux phases réactionnelles consécutives ont été distinguées.
Structure and properties of acrylonitrile‐functional silane copolymers
Authors: Rao V. Lakshmana , Eshwar M. C. , Babu G. N.
Published: April 2003

X‐ray diffraction, thermomechanical and thermogravimetric studies on polyacrylonitrile (PAN), poly(acrylonitrile‐co‐vinyl‐tris(methoxyethoxy)silane) (poly(AN‐co‐VTMES)), poly(acrylonitrile‐co‐vinyltriethoxysilane) (poly(AN‐co‐VTES)), and poly(acrylonitrile‐co‐methylmethacryloyloxypropyltrimethoxysilane) (poly(AN‐co‐MPTMS)) have been made for investigating their structure. The thermomechanical analysis results revealed that the glass transition temperature (Tg) for the copolymers are lower than for PAN. The lowering of Tg in poly(AN‐co‐MPTMS) is more significant than those of poly(AN‐co‐VTES) and poly(AN‐co‐VTMES). The incorporation of silane comonomers in the copolymer resulted in the reduction of crystallinity but the crystalline lattice was not disturbed, what is suggested to be due to the location of the silane containing segments in the amorphous region. Thermal stability of the copolymers was also studied.
Immobilization of trypsin on poly(alginic acid‐g‐glycidyl methacrylate‐co‐methyl methacrylate)
Authors: Reddy C. Raghuram , George Anne , Reddy C. Rami
Published: April 2003

A method of enzyme immobilization by graft copolymerization onto alginic acid is reported. Glycidylmethacrylate along with methyl methacrylate was used as a vinylating reagent. The enzyme trypsin has been chosen for our studies. The effects of various parameters such as pH optima, temperature optima, pH stability, thermal stability, storage stability, and re‐usability were studied.
Antioxidants and stabilizers, 103. Typical impurities of antiozonants, N‐alkyl‐N′‐phenyl‐1,4‐phenylenediamines, and their antioxidant behaviour
Authors: Taimr Luděk , Pospíšil Jan
Published: April 2003

In various samples of the industrially used antiozonant N‐isopropyl‐N′‐phenyl‐1,4‐phenylenediamine (IPPD, Ib), a typical, intensively coloured impurity was detected, and its structure was determined (IIb). The same compound IIb was prepared independently by an acid catalyzed reaction of 4‐aminodiphenylamine (IV) with N‐isopropyl‐N′‐phenyl‐1,4‐benzoquinonediimine (IIIb). IIb is formed by the same route also in technical IPPD, both in the production process and during storage. In the autoxidation of squalene (rubber model) IIb behaves as an effective antioxidant. The simultaneous presence of IPPD does not produce any antagonistic effect. IIa, which is an analogous impurity of technical N‐(1,3‐dimethylbutyl)‐N′‐phenyl‐1,4‐phenylene‐diamine (HPPD, Ia), behaves as an antioxidant similar to IIb. Thus, with respect to the antioxidant effect, the presence of impurities IIa or IIb in technical HPPD or IPPD does not matter.
Solvent/nonsolvent solubility and polarity parameters in fractional separation of oligomers. 1. Epoxy resins
Authors: Spychaj Tadeusz
Published: April 2003

Epoxy resins from epichlorohydrin and bisphenol A have been fractionated in various binary solvent/nonsolvent systems. Low molecular weight (M ⋍ 400) and higher molecular weight (M ⋍ 1000) resins were fractionated using solvent/nonsolvent pairs in a wide range of polarities. Two solvent‐derived parameters: total solubility parameter δT and polarity index P′ have been applied to correlated experimental data. An empirical solubility diagram in coordinates P′ = f(δT) prepared on the basis of phase separation experiments, makes it possible to predict whether other solvent/nonsolvent pairs will work as efficient systems for epoxy resin fractionation. Two areas of solvent/nonsolvent parameters have been found for efficient epoxy resin fractionation: the first δT ⋍ 15.4–19.0 MPa1/2; P′ ⋍ 0.4−2.8 and the second of δT ∼ 19.5, P′ ∼ 6.0. In addition, the fractional precipitation of epoxy resins permits an evaluation of δT and P′ range of the resin for specific fractionation mixtures.
Studies on β‐picolinium‐p‐chlorophenacylide initiated copolymerization of methyl methacrylate with styrene
Authors: Nigam S. K. , Shukla A. K. , Saini S. , Kumar P. , Srivastava A. K.
Published: April 2003

The alternating copolymerization of methyl methacrylate (MMA) with styrene (S) using β‐picolinium‐p‐chlorophenacylide (β‐PCPY) as radical initiator at 55, 60, and 65°C for 3 h has been kinetically investigated. The copolymerization rate (Rp) is proportional to the square root of [β‐PCPY] and indicates bimolecular termination. The average degree of polymerization decreases as [β‐PCPY] increases. The values of kp2/kt and energy of activation have been evaluated as 1.43 · 10‐3 l mol‐1 s‐1 and 87 kJ mol‐1, respectively. The NMR spectroscopy has been used to determine the structure, composition, and stereochemistry of copolymers.
Influence of carbon black filler on the autohesion of polybutadiene rubber
Authors: Oppermann Wilhelm , Chakraborty Kalyan Kumar
Published: April 2003

A study of the autohesion of polybutadiene rubber filled with different amounts of carbon black has been made. When the elastomer is uncrosslinked, the autohesive strength initially rises linearly with square root of contact time and finally shows a time independent course. The initial autohesion at time zero increases almost linearly with increasing carbon black content, while the ultimate strength is markedly influenced only when the filler content exceeds 30%. The time necessary to achieve ultimate strength decreases significantly when small amounts of filler are added.

Experiments with slightly crosslinked polybutadiene did not show a characteristic time dependence. The autohesive strength increases strongly up to 30% carbon black content and seems to decrease again on further addition of filler.
Functionalization of atactic polypropylene using allyl and azide compounds
Authors: Borsig Eberhard , Braun Dietrich
Published: April 2003

Atactic polypropylene was functionalized by reaction with dicumyl peroxide (8 wt.−%) and allyl compounds (8 wt.−%) such as eugenol methylether, allylphenylether, allylurea, N‐allylthiourea, diethyl allylmalonate, N‐allylaniline at 170°C. Using tert‐butyl azidoformate carbamate groups (1.8 wt.−%) were attached to atactic polypropylene. The mechanism of both types of reactions is discussed.
Characterization of low molecular compounds in dashboard foils by extraction, preparative high performance liquid chromatography, and IR‐spectroscopy
Authors: Standt Ulrich‐Dieter
Published: April 2003

A procedure to obtain information concerning the low molecular weight compounds of dashboard foils is described. Solvent extracts of the foils were fractionated by preparative reversed or normal phase HPLC, respectively. The fractions were characterized by their infrared spectra. The benefits and the shortcomings of the two methods are discussed.
Studies on graft copolymerization of methyl methacrylate onto chemically modified tussa silk fibers. Peroxydisulfate‐thiourea redox system
Authors: Mohanty A. K. , Singh B. C. , Misra M.
Published: April 2003

The graft copolymerization of methyl methacrylate (MMA) onto chemically modified tussa silk fibers in aqueous media using potassium peroxodisulfate‐thiourea redox initiator system was studied at 60°C. The effects of time of reaction, concentrations of oxidant, thiourea (TU), monomer (M), amount of silk fibers on graft yield have been studied. The effects of reaction medium, acid concentration, and some inorganic salts and organic solvents on grafting have also been investigated. A significant increase in percent of grafting was observed with increasing monomer concentration to 65.86 · 10−2mol · 1−1; a further increase of monomer concentration is associated with the decrease of graft yield. The graft yield increases with an increase of thiourea concentration up to 10 · 10−1mol · 1−1, beyond which it decreases very significantly. A measurable increase of the graft yield was also observed with an increase of the oxidant concentration up to 0.08 mol · 1−1beyond which the graft yield decreased. The graft yield was medium dependent. The reaction mechanism of the grafting process has been proposed and a rate expression has been derived on the basis of experimental findings. IR spectra of the grafted fiber and original fiber have been taken and their characteristic bands have been identified. The thermal behaviour of the original and grafted silk fibers has been studied by TGA and DTG analysis. Grafting has improved thermal stability as well as the light fastness of silk dyed with Rhodamine B.
The effect of γ‐irradiation on optical and electrical properties of polycarbonate
Authors: Amin Mohamed , Darwish Khairia Ahmed , Mounir Mohamed
Published: April 2003

Poly‐(bisphenol A carbonate) (PC) samples were exposed to different doses of γ‐rays from a 60Co source (from 0.05 to 0.3 M rad) at room temperature. Conductivity and dielectric constant as well as optical measurements were carried out. It was noticed that almost no work has been reported on the electrical conductivity of polycarbonate at high temperatures. γ‐irradiation of polycarbonate is believed to create free radicals which increases the state of disorder and perturb the orientation of dipoles inside the polymer. At about 95°C, the electrical conductivities of irradiated samples were found to increase by nearly one order of magnitude with respect to the unirradiated one. The dielectric constant, ϵ, of fresh polycarbonate was nearly temperature independent over a range of ∼ 70°C, then it increased with temperature, but for γ‐irradiated samples (from 0.05 to 0.3 M rad) the dielectric constant increased continuously with temperature and also with respect to the fresh sample what confirms the effect of γ‐irradiation in perturbing the orientation of the dipoles in the polymer. It was found that the UV absorption spectrum has a broad band at 0.280 μm and the absorption intensity was strongly dependent on the dose of γ‐irradiation.
Nitric oxide initiated polymerization of acrylonitrile
Authors: Mishra Mahendra Kumar
Published: April 2003

Nitric oxide initiated polymerization of acrylonitrile in dimethylsulfoxide was carried out. The dependence of monomer and initiator concentrations and temperature on polymer yield and initial rate of polymerization (Rin) was studied. The over‐all activation energy of polymerization was found to be about 19.96 kcal · mol−1 (83.43 kJ · mol−1). The polymerization of acrylonitrile appears to occur via free radical mechanism. A kinetic scheme and rate expression have been proposed.
Macromolecular structure of coals, 7. Mass spectrometry of pyridine extracts and depolymerized coal
Authors: Lucht Lucy M. , Hill Mary E. , Peppas Nikolaos A.
Published: April 2003

Electron impact mass spectrometry and mass ion kinetic energy spectrometry were used to analyze: (i) the structure of uncrosslinked, predominantly aliphatic chains obtained by pyridine extraction of bituminous coals; and (ii) the identity of compounds found in depolymerized coal samples produced by the technique of Hooker et al. (1986).
Degradation of polypropylene: Effect of stabilizers
Authors: Choudhary V. , Varshney S. , Varma I. K.
Published: April 2003

The relative effectiveness of five commercially available stabilizers on the photooxidation and thermal ageing of polypropylene (PP) was investigated by following changes in mechanical properties. Samples of PP containing different percentages of Cyasorb UV‐531 were prepared (designated as PC0.5‐31, PC1‐31, PC1.5‐31, and PC2‐31, respectively). The effect of photooxidation on thermal behaviour was investigated by differential scanning calorimetry and thermogravimetric analysis. 2‐Hydroxy‐4‐n‐octyloxy benzophenone (2% w/w) was most effective in stabilizing PP towards discolouration and brittleness. After 32 h irradiation, 81% retention in yield strength was observed in case of PC1‐31 against 18% in case of PP.
Study of polymerization of methacrylamide initiated by persulphate with different activators
Authors: Behari K. , Raja G. D. , Lal M.
Published: April 2003

The aqueous polymerization of methacrylamide was studied by using persulphate/malic acid and persulphate/ethanolamine redox pairs under nitrogen atmosphere. The order with respect to persulphate was found to be one half with both the redox systems. Malic acid and ethanolamine show half order and zero order, respectively. Methacrylamide has first order dependence on the rate of polymerization initiated by K2S2O8‐malic acid system and one and half order dependence on the rate of polymerization initiated by K2S2O8‐ethanolamine redox pair. Viscometric average molecular weight was determined for the samples obtained under different kinetic conditions.
Untersuchungen zum mechanismus der thiol‐en‐photoadditionspolymerisation
Authors: Klemm Elisabeth , Holfter Uta , Sensfuß Steffi , Flammersheim Hans‐Jürgen
Published: April 2003

DSC‐ und ESR‐Messungen zur photosensibilisierten Polymerisation von 1,8‐Dithio‐3,6‐dioxaoctan/Phthalsäurebisallylester zeigen, daß die Reaktion in jedem Reaktionsschritt photoaktiviert erfolgt und daß C‐Radikale intermediär auftreten. Modelluntersuchungen am System 1‐Octanthiol/Phenylallylether ergaben, daß bevorzugt Photoaddition eintritt und daß Radikalrekombinationen von untergeordneter Bedeutung sind. Diese Befunde werden durch 1H‐, 13C‐NMR‐ und Massenspektren belegt.
Conductivity variations of iodine‐ and tungsten chloride‐doped polyacetylene under applied voltages
Authors: Chen Show‐An , Huang Ching‐Feng
Published: April 2003

For iodine‐ and tungsten chloride (WCl6)‐doped polyacetylene (PA), conductivity shows decreasing with time on standing in inert atmosphere. The doping levels investigated for the former are 0.006 to 0.088 mol per mol, and for the latter 0.006 to 0.053. As a voltage is applied, the conductivity shows an accelerated decreasing with time. As the voltage increases further, the acceleration becomes more pronounced; and the doped PA can even break into two pieces as a critical voltage is reached. This critical voltage (11.0 V to 26.5 V for the iodine cases and 13 V to > 40 V for the WCl6 cases) is found to increase with decreasing doping level. This break‐down is attributed to the occurrence of nonuniform doping in the doped PA.
The use of micro‐HPLC with gradient elution for the characterization of phenol‐formaldehyde resins
Authors: Preussler Vít , Šlais Karel , Hanuš Jiří
Published: April 2003

Phenol‐formaldehyde resins of the Novolak and Resol type were chromatographed on a reverse‐phase micro‐column packed with octadecylsilane on silica gel. A good separation of most components was achieved by the use of gradient elution with methanol‐water; the contents of methanol in the mobile phase increased continually from 10 to 90%. The gradient was generated in a simple tubular mixer with an internal volume of 1.5 ml. Samples were applied to the column in a non‐eluting solvent, using a six‐port injection value with a 10 μl sample loop. The method, which shows a good reproducibility, is suitable for the characterization of phenol‐formaldehyde resins.
Morphology of ultrahigh molecular weight polyethylene surface slid against steel
Authors: Kōmoto Tadashi , Hironaka Seiichiro
Published: April 2003

A morphological study was made to examine the friction and wear mechanisms of ultrahigh molecular weight polyethylene in air and water by means of transmission electron microscopy of a carbon replica film of a very thin layer of the polymer surface slid against a steel ball. Electron diffractions revealed that a molecular orientation with a typical fiber pattern was formed in the friction in air, while thin ribbon‐like crystals with particular crystal orientations were formed in water in a way that the sliding took place on the crystallographic a—c plane, giving rise to a low friction coefficient of the polymer.
Oberflächenstrukturierung polymerer Fasern durch UV‐Laserbestrahlung. 1. Grundlagen der UV‐Laserbehandlung von Polymeren
Authors: Bahners Thomas , Schollmeyer Eckhard
Published: April 2003

Die Oberflächenstruktur stellt ein herausragendes Merkmal einer textilen Faser dar. Sie beeinflußt Gebrauchs‐ und Verarbeitungseigenschaften wie Reibungsverhalten, Benetzungseigenschaften, Adsorptionsvermögen von Farbstoffmolekülen und vor allem Haftungsverhalten von Partikeln, Pasten und Pigmenten. Die Möglichkeit, diese vielfältigen Eigenschaften durch gezielte Oberflächenmodifikation zu beeinflussen, machen Technologien für die Textilveredlung wünschenswert. Als neuartiges Verfahren soll in dieser Artikelfolge die Bestrahlung von Synthesefasern mit gepulsten UV‐Lasern (Excimerlasern) vorgestellt werden. Diese Technologie wird für die mikrolithographische Bearbeitung und auch für das Schneiden und Bohren von polymeren Werkstoffen eingesetzt. Dabei hat sich gezeigt, daß gezielte, hochpräzise Oberflächenbehandlungen möglich sind, ohne das Grundmaterial zu schädigen. Im ersten Beitrag zur Oberflächenstrukturierung von Synthesefasern mit UV‐Lasern sollen Grundlagen der UV‐Laserbehandlung betrachtet werden.
Oberflächenstrukturierung polymerer Fasern durch UV‐Laserbestrahlung. 2. Phänomenologische Untersuchung der durch Laserbestrahlung erzeugten Oberflächenstrukturen
Authors: Bahners Thomas , Schollmeyer Eckhard
Published: April 2003

Dieser Beitrag berichtet über die Bestrahlung von Synthesefasern mit gepulster UV‐Laserstrahlung (Excimerlaser) als neuartige Technologie zur Erzeugung regelmäßiger Oberflächenstrukturen. Dabei werden Laserwellenlängen von 193 und 248 nm eingesetzt. Am Beispiel verschiedener Synthesefasern werden die Kenndaten der Oberflächenstrukturen in Abhängigkeit von den Bestrahlungsbedingungen rasterelektronenmikroskopisch untersucht. Anhand der Meßdaten werden phänomenologische Gesetzmäßigkeiten ermittelt.