bluuebunny/crossref_metadata_2025 huggingface dataset:
Water‐soluble polyamides as potential drug carriers, II. Amine‐functionalized poly (α,β‐d,l‐aspartamide) derivatives
Authors: Neuse Eberhard W. , Perlwitz Axel , Schmitt Siegfried
Published: April 2003

Several derivatives of poly(α,β‐D,L‐aspartic acid) (2) comprising amine functions as side chain components are synthesized for use as macromolecular drug carriers. The structures of the target polymers are designed so as to provide complete solubility in water, a prerequisite for smooth intravenous administration, and the strategy of derivatization reflects the requirement for the performance of all reaction steps in a partially or entirely aqueous phase. The poly(aspartic acid) (2) — a known synthetic polyamide obtained from poly(succinimide) (1) and composed of both α‐ and β‐ peptide units in the chain — is coupled with ethylenediamine, diethylenetriamine, N‐(2‐hydroxyethyl)ethylenediamine, and hydrazine, respectively, in the presence of water‐soluble carbodiimides. This gives the poly(aspartamides) 3 to 6 possessing primary amino side groups. More efficaciously, circumventing the intermediacy of the polyacid 2, polymers 3 to 6 are obtained through nucleophilic opening of the imide rings in 1 by the same amine reactants. The analytically and spectroscopically characterized, water‐soluble target polymers 3 to 6 have inherent viscosities ranging from 5 to 20 ml g−1 and possess the structural prerequisites for side‐chain drug anchoring involving the spacer‐bound amino groups. The susceptibility of these functional groups to substitution as a measure of their drug binding capabilities is demonstrated by conversion of 5 and 6 to the N‐acryloylated derivatives 7 and 8 — with 7 further derivatized to give 9 — and by condensation of 5‐formylsalicylic acid with the bidentate — ethylenediamine side group in 4 to give the conjugate 10 containing the bioactive salicylyl group as a side‐chain component.
Introduction of hydroxyethyl and glycidyl ester groups into methyl methacrylate copolymers by polymer analogous reactions
Authors: Sandner Barbara , Ziegler Hans‐Jörg , Bischof Claus
Published: April 2003

The reactions of 2‐chloroethanol and epichlorohydrin (ECH), respectively, with alkali salts of partially hydrolyzed methyl methacrylate (MMA) polymers as well as with MMA copolymers containing free carboxy groups were studied. Quaternary ammonium halogenides R4NX are effective catalysts of these reactions. Up to 80% of alkali carboxylate groups were converted into hydroxyethyl ester groups to yield completely soluble copolymers. By reaction of ECH with alkali salts of the copolymers, crosslinked products were obtained. The gel fraction may be reduced from 87% to 5% if the reaction is carried out in the presence of R4NX. MMA‐copolymers containing free carboxy groups react with an excess of ECH in the presence of R4NX via the chlorohydrin ester and dehydrochlorination (transepoxidation) to produce completely soluble glycidyl ester copolymers of low chlorine content (≤0.4%). Yields of epoxy groups up to 95% have been attained.
Bifunctional initiators, II. Bulk polymerization of styrene initiated by 4,4′‐azobis(4‐cyanopentanoyl)‐bis (α‐methylolbenzoin methyl ether)
Authors: Önen Aysen , Yağci Yusuf
Published: April 2003

Azo‐benzoin initiators are useful for the synthesis of polymers with photoactive end groups. The kinetics of the bulk polymerization of styrene initiated by 4,4′‐azobis(4‐cyanopentanoyl)bis(α‐methylolbenzoin methyl ether) (ABME) was investigated. On the basis of kinetic parameters, it was found that azo‐benzoin initiators exhibit initiator properties similar to that of common azo initiators. A relatively high chain transfer constant of the initiator (C1) may be attributed to the presence of α‐methylolbenzoin methyl ether groups in the structure.
Kinetic studies on bitumen air‐blowing polymerization in presence of sodium sulphide
Authors: Antony T. P. , Francis D. Joseph
Published: April 2003

Sodium sulphide is found to accelerate the rate of bitumen air‐blowing polymerization. The kinetic analysis of the process showed that it behaves as a first order reaction below 280°C. The rate constants obtained were used to determine the Arrhenius activation parameters.
Syntheses and properties of UV‐autocurable prepolymers. Semicrystalline urethane‐multiacrylates
Authors: Chiang Wen‐Yen , Chan Shao‐Ching
Published: April 2003

A series of UV‐autocurable urethane‐multiacrylate prepolymers, which were semicrystalline and showed melting points in the region of 40–50°C, was synthesized. Also, the effects of curing temperature and acrylic functionality on the structure and properties of the cured films were investigated.

These prepolymers are solids and opaque at room temperature. In general, UV curing reactions of solid prepolymers are less efficient when compared with those of liquid prepolymers. UV curing reactions at curing temperatures below the melting point (Tm) of the prepolymers produced semicrystalline urethane‐multiacrylate cured films. On the contrary, UV curing reactions above Tm destroyed the crystalline phase of the prepolymers and improved the transparency of the cured films. The films cured below Tm of the prepolymers had higher both breaking strength and Young's modulus, and a higher glass transition temperature (Tg), but a lower elongation at break than those cured above Tm. Such curing temperature effects were attributed to the retention or disappearance of the crystalline structure of the prepolymers during UV curing reaction. At curing temperatures below Tm, an increase in acrylic functionality of the prepolymer resulted in a fast curing rate and a higher crosslinking density of the cured films. Therefore, an increase in acrylic functionality of the prepolymers gave cured films with higher breaking strength and Young's modulus, but a lower elongation at break.
Synthese und charakterisierung von stationären phasen auf der basis von mit epoxidiertem polybutadien (PBDE) modifizierten polykieselsäuren. I. Untersuchungen zur oberflächenmodifizierung von polykieselsäuren mit epoxidierten polybutadienen
Authors: Heublein G. , Erler U. , Ulbricht A. , Winkelmann H.
Published: April 2003

Die vollständige Modifizierung der Oberfläche polykieselsäurehaltiger Adsorbentien mit epoxidierten Polybutadienen gelingt bei optimaler Syntheseführung unter Kombination von Eigenschaften des Polymeren (Funktionalität, pH‐Stabilität) und des anorganischen Trägers (Druckstabilität, Textur). Dabei werden bei Verwendung von Polybutadienen mit hohem Anteil 1,4‐verknüpfter Struktureinheiten die besten Ergebnisse erzielt. Mit zunehmender Oberflächenpolymerkonzentration verändern sich die Eigenschaften der erhaltenen Reaktionskomposite wie beispielsweise das Adsorptionsverhalten gegenüber Farbstoffen, die spezifische Oberfläche, das Brutto‐σ‐Akzeptor‐verhalten und die Oberflächenpolarität in charakteristischer Weise. Die Übertragbarkeit einer optimierten Syntheservariante der Reaktionskomposite auf typische Trägermaterialien für verschiedene Einsatzgebiete wie beispielsweise HPLC, Affinitätschromatograpie oder Wirkstoffimmobilisierung wird bewiesen.
Synthese und charakterisierung von stationären phasen auf der basis von mit epoxidiertem polybutadien (PBDE) modifizierten polykieselsäuren. III. Untersuchungen zur synthese aminofunktionalisierter trenn‐und trägermaterialien
Authors: Erler U. , Heublein G.
Published: April 2003

Durch heterogene polymeranaloge Reaktionen epoxidierter Polybutadiene mit Oberflächen von polykieselsäurehaltigen Adsorbentien können bei der Umsetzung von Epoxygruppen des Polymeren mit reaktiven Diaminen aminofunktionalisierte Trenn‐ und Trägermaterialien erhalten werden. Der Vergleich der Eigenschaften von Reaktionscompositen, welche unter Variation der Synthesebedingungen nach verschiedenen Verfahren hergestellt wurden, eröffnet die Möglichkeit, im Sinne einer gezielten Reaktionssteuerung sowohl Polymer‐ und Amingehalt als äuch den Anteil primärer und sekundärer Aminogruppen der resultierenden Materialien speziellen Anwendungszwecken anzupassen.
Dynamic vulcanization of PVC‐epoxidized natural rubber miscible blend: The effects of dimaleimide crosslinking
Authors: Varughese K. T. , De P. P. , Sanyal S. K.
Published: April 2003

Poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) miscible blends were vulcanized “dynamically” by N,N′‐m‐phenylene dimaleimide during the melt blending process. ENR component in the blend was partially crosslinked in this process. Miscibility of the blend components was not impaired. On the other hand the microheterogeneity between ENR and PVC was reduced due to the improved interfacial adhesion. Dynamically vulcanized PVC/ENR blends improved the elastic deformation. Thermal stability was greatly improved in blends due to the dimaleimide vulcanization process.
Polymerisation von n‐substituierten maleimiden in epoxidverbindungen, 1
Authors: Lüders Günter , Merker Eberhard , Raubach Heinz
Published: April 2003

N‐substituierte Maleimide Polymerisieren in Glycidethern mit einer Reaktion erster Ordnung, ausgelöst durch eine Startreaktion zweiter (pseudo‐erster) Ordnung. Die Aktivierungsenergie der Startreaktion liegt mit fast 70 kJ/mol oberhalb, die der Polymerisation mit 48 kJ/mol weit unterhalb der Werte der rein thermischen Maleimidpolymerisation von etwa 60 kJ/mol. Die Werte werden durch DSC‐Untersuchungen von Bismaleimiden in Diepoxiden bestätigt. Die Startreaktion verläuft ab 100°C mit deutlichef Exothermie unter Epoxidverbrauch, Rotfärbung und Bildung von Radikalen mit g = 2.0034.

Die Polymerisation wird durch Säuren und nicht durch Radikalfänger abgebrochen. Es werden Maleimid‐Oligomere mit Pn = 5 – 7 erhalten, die glycidether‐spezifische Gruppen tragen und katalytisch wirken. Eine anionische Initiierung wird diskutiert.
Polymerisation von N‐substituierten maleimiden in epoxidverbindungen, 2
Authors: Lüders Günter , Schulz Günter , Goering Harald , Raubach Heinz
Published: April 2003

Die Polymerisation von N‐substituierten Maleimiden in Epoxiden wird durch eine Startreaktion zweiter (pseudo‐erster) Ordnung anionisch initiiert. Die Gesamtreaktion wurde mit Hilfe der Ausschlußchromatographie (SEC) bis zu hohem Umsatz verfolgt. Unter 180°C werden Oligomere des Phenylmaleimids mit einem Polymerisationsgrad bis 10 und enger Molmassenverteilung gebildet. Die Geschwindigkeitskonstante der Polymerisation ist k1(120°C) = 2,18·10‐5 (SEC) bzw. 5,24·10‐5 s‐1 (Dilatometrie). Uber 200°C werden Copolymere mit Alternierungstendenz erhalten. Mit Hilfe der Ergebnisse wird das dynamisch‐mechanische Verhalten von Modellformstoffen aus Bismaleimiden und Bisphenol A‐Epoxidharzen interpretiert.
Neue polymer‐additive, 2. Pigmente und flammhemmer auf basis von modifizierten siliciumdioxiden
Authors: Bräuer Leopold , Gruber Heinrich , Greber Gerd
Published: April 2003

Styrol‐modifiziertes Siliciumdioxid (SD) wurde mit aromatische Amino‐Gruppen enthaltenden Vinylmonomeren copolymerisiert. Durch Diazotierung des so erhaltenen Amino‐SD und Kupplung mit Phenolen wurden neue Pigmente auf SD‐Basis hergestellt. Pigmente und Flammhemmer wurden auch durch Kondensation der Amino‐SD mit Carboxyl‐Gruppen enthaltenden Farbstoff‐ bzw. Flammhemmer‐Komponenten erhalten. Durch den Einsatz der gepfropften SD sind Additive mit hohem Wirkstoffgehalt zuganglich. Diese neuen Additiv‐Typen auf SD‐Basis, in denen organische Wirkkomponenten durch stabile kovalente Bindungen mit dem anorganischen Additiv SD verknüpft sind, zeichnen sich durch gute Verträglichkeit, hohe Temperaturbeständigkeit und Migrationsechtheit aus.
Oberflächenstrukturierung polymerer fasern durch uv‐ laserbestrahlung. 10. UV‐laserinduzierte pfropfcopolymerisation von acrylsäure auf polypropylen
Authors: Kesting Wolfgang , Knittel Dierk , Schollmeyer Eckhard
Published: April 2003

Oberflächen von Polypropylen (PP)‐Folien werden durch UV‐laserinduzierte Pfropfcopolymerisationsreaktionen von Acrylsäure anionisch modifiziert. Die Bestrahlung der hydrophoben PP‐Folien erzeugt hierbei eine Hydrophilie. Die Ausbeute von aufgepfropften Polyacrylsäure‐Seitenketten wird in Abhängigkeit der experimentellen Parameter bestimmt. Im Gegensatz zu Pfropfcopolymerisationsreaktionen mit herkömmlichen UV‐Strahlungsquellen (Hg‐Hochdruckdampflampen) kann schon mit sehr kurzen UV‐Laserbestrahlungszeiten eine chemische Modifizierung der PP‐Oberfläche erzielt werden. Darüber hinaus ist die Verwendung von Photoinitiatoren und Photosensibilisatoren nicht notwendig.
Durability of radiation sterilized polymers, XIV. The effect of nucleating agent on the melt behaviour of irradiated polypropylene
Authors: Aziz Sharifah H. , Kadir Zahrah Abdul , Yoshii F. , Makuuchi K. , Ishigaki I.
Published: April 2003

By the addition of nucleating agent (NA), the molecular weight of gamma‐irradiated polypropylene (PP) decreases more than that of PP without NA. In the first run of differential scanning calorimetric (DSC) measurement, the melting point (T m) of PP with NA was lower than the one without NA because of larger molecular scission which occurred during irradiation. On the contrary, in the second run, Tm of PP with NA, was found to be higher than that of PP without NA. Due to the presence of NA, the molecular chains become shorter during irradiation and therefore rearrangement of the chains is easier during crystallization after the first run, this contributes to an increase in Tm.
Polyurethane‐crosslinked epoxy resins. I. Mechanical behavior
Authors: Han J. L. , Tseng S. M. , Mai J. H. , Hsieh K. H.
Published: April 2003

Polyurethane (PU) prepolymers based on poly(butylene adipate) (PBA) and poly(oxytetramethylene) (PTMO) polyols were employed as a crosslinking agent to the diglycidyl ether of bisphenol A (DGEBA). Then the DGEBA was cured with a tertiary amine catalyst to form PU‐crosslinked DGEBA.

The tensile strength of both the PU(PBA)‐crosslinked DGEBA and PU(PTMO)‐crosslinked DGEBA systems increased to a maximum value with increasing PU content in the system and then decreased with further increasing PU content.

Izod impact property of these PU‐crosslinked DGEBA indicated that the PU(PBA)‐crosslinked DGEBA had much more significant improvement than the PU(PTMO)‐crosslinked DGEBA. On the contrary, the fracture energy (G1 C value) of the resultant PU‐crosslinked DGEBA showed that the PU(PTMO)‐crosslinked DGEBA had much higher G1 C values than the PU(PBA)‐crosslinked DGEBA.
Oriented polymer networks obtained by photopolymerization of liquid‐crystalline monomers
Authors: Broer D. J. , Gossink R. G. , Hikmet R. A. M.
Published: April 2003

In this paper a new class of oriented polymers is introduced: highly crosslinked polymer networks obtained by photopolymerization of oriented liquid crystalline (LC) monomers. Orientation of these monomers can be induced in the same manner as usual for conventional LCs applied in LCDs: with the aid of an electric or a magnetic field, or using surface orientation. Photopolymerization offers the advantage that a temperature can be chosen right within the LC temperature region.

The resulting polymer networks show a high degree of ordering which is somewhat dependent on the polymerization temperature, as demonstrated by the amount of birefringence. This ordering is maintained over a wide temperature region, contrary to that in LC side‐chain polymers. Apart from their optical properties, uniaxially ordered polymer networks show anisotropy also in other physical properties, such as the thermal expansion coefficient and modulus.
Wirkungsweise von stabilisatoren in polymeren unter berücksichtigung der 2‐hydroxyphenylbenzotriazole
Authors: Kramer Horst E. A.
Published: April 2003

In the first part a survey is given on UV screeners, UV absorbers, quenchers of excited states, antioxidants and peroxide decomposers.

In the second part UV absorbers, e. g. Tinuvin P (2‐(2'‐hydroxy‐5'‐methylphenyl) benzotriazole, Scheme 8) are described in detail where intramolecular proton transfer occurs in the excited state (TIN(intra) ). This proton transfer may be accompanied and/or followed by very fast and effective temperature dependent radiationless deactivation processes which are promoted by internal vibrations and librations of the molecule. ‐ In polar solvents or in polymers with polar groups some of the molecules convert their intramolecular hydrogen bond into an intermolecular one (TIN (inter) ). TIN (inter) cannot be considered any longer as UV stabilizer. Due to its high triplet quantum yield it may even initiate photodegradation processes of itself and of the polymer. From this follows that the TIN molecule can only act as stabilizer if the intramolecular hydrogen bond is intact. This can be answered from the UV absorption spectrum.
Photoconductive polymers: Structure, mechanisms and properties
Authors: Haarer Dietrich
Published: April 2003

Charge carrier transport properties of organic polymers can vary over a wide range. The paper shows that the electron‐ and hole mobilities of polymers with pendant photoconductive groups (i. e. carbazole) are on the order of 10‐6 cm2/Vs. In these materials the flow of electronic charge is maintained by the overlap of the π‐orbitals of the pendant molecular groups. The large variation of this short‐range interaction, depending on the local configurations encountered in polymer glasses, leads to a large variation of hopping probabilities and, hence, to wide rate‐distributions. These distributions are reflected in the slow algebraic decay characteristics of the observed photocurrents. The typical time exponents α (α < 1) are shown to carry a great deal of physical information, if the dynamical range of the experiments is sufficiently large. The paper also refers to quasi‐conjugated polymers (polysilanes) whose dynamic transport parameters are about 103 times better (faster) as compared to polymers with pendant groups. These new materials open interesting aspects for the development of new polymeric materials with better transport parameters and, hence, shorter 'switching times'.
TRANSPARENTE POLYMERE MEHRPHASENSYSTEME
Authors: Biangardi Harald J. , Sturm Harald , Kostersitz Georg
Published: April 2003

Usually two phase polymer blends are not transparent because of differences in the refractive indices of their components and the resulting light scattering. By means of model calculations on the basis of the Mie‐theory, the conditions for transparency in two‐phase polymer blends are investigated. The models used are homogeneous spheres or spheres with a core‐shell morphology imbedded in the polymer matrix. The light scattering of these particles is calculated as a function of diameter, refractive index, wavelength and particlecomposition. Results are presented that show the limits of diameter and difference in the refractive indices between matrix and particle for homogeneous particles to obtain transparency. In the case of large differences in the refractive indices or of large diameters the use of spheres with a core‐shell morphology is favourable. Depending on the refractive indices of the respective phases, there exists an optimal composition of these spheres to obtain transparent polymer‐blends. Another way to transparency is the minimization of light scattering by interparticle interferences, which can be achieved by special types of block‐copolymers.
POYCARBONAT UND LICHT
Authors: Käumpf Günther , Freitag Dieter , Witt Werner
Published: April 2003

Polycarbonate (PC) based on 4,4'‐dihydroxydiphenyl‐2,2‐propane has adchieved an outstanding market relevance due to its extraordinary physical and technical properties, especially due to the combination of excellent impact strength and high heat distortion temperature (HDT) combined with good optical and electrical properties.

This very attractive balance of properties has led to a broad and still expanding use of PC in different optical application areas. Therefore it has reached a significant importance as a material for glasing (compact sheet and twin wall sheet) and also for optical lenses. For lenses the high refraction index of PC (n = 1,58) and its low density have shown as additional advantages. Recently PC was introduced as a base material for polymeric optical fibers (POF) in the market: Despite its inherently high optical loss (about 800 dB/km at λ = 820 nm) PC has proved as an attractive material because of its high refractive index (cheap cladding, narrow bending radii) and its good HDT (use at relatively high temperatures, e.g. near the engine of automobiles), so far the maximum fiber length will not exceed 30 m.

During the last decade PC with extremely high flow and purity became the material of choice for music consumer industry (compact disk: CD) and for optical data storage technology. So far all the CDs were produced worldwide from PC (1988: 450 Mio CD, 1989 about 650 Mio CD). These special PC grades are used for WORM disks (write once read multiple) and EOD disks (erasable optical disks) with diameter up to 13 cm. These disks are still in the phase of market introduction. For disk diameters greater than 13 cm up to 30 cm experimental products with very low birefringence combined with increased stiffness are currently under development (e.g. blends of modified PC with modified SAN).

The continuous improvement of the commercial PC grades and the new development of structurely modified PC and special blends based on PC will lead to a further increasing consumption of PC and to further expanding applications of PC especially in the optical market area.
Graft copolymers of starch and poly(ethyl acrylate) dilution effects
Authors: Okieimen Felix E. , Egharevba Felix , Jideonwo Arthur
Published: April 2003

Graft copolymerization of ethyl acrylate onto starch initiated by ceric ion in an aqueous medium was studied at 29°C. It was found that the grafting frequencies and molecular weights of grafted poly(ethyl acrylate) changed from 2 graft polymer molecules per 104 anhydroglucose units (AGU) and 3.03 · 105 to 34 and 6.80 · 105, respectively, when the starch content was varied from 1.0 wt.‐% to 0.2 wt.‐%. The influence of dilution of ceric ion on the extent and rate of graft polymerization of ethyl acrylate onto starch was also examined.
Graft copolymerization of 4‐vinylpyridine onto cotton. The ceric ion concentration effect
Authors: Leza M. L. , Casinos I. , Guzmán G. M.
Published: April 2003

For the study of the effect of ceric ammonium nitrate (CAN) initial concentration on the graft copolymerization of 4‐vinylpyridine (4‐VP) onto cotton three series of experiments were carried out. In the first one the CAN concentration was varied from 0.5 to 100 mmol/l and so, parallely, the total nitrate ion concentration. In the other two series the CAN initial concentration was varied, but keeping the total nitrate ion concentration constant at 1.09 and 1.59 M, respectively, by sodium nitrate addition. Increasing the ceric salt concentration the graft yield and total conversion reached a maximum. When the nitrate ion concentration was kept constant the maximum graft yield value was achieved at CAN concentrations lower than when it was varied. However, for all the three series of experiments the maximum graft yield value was nearly the same. The ceric ion consumption increased with increasing initiator concentration. The higher the total nitrate ion concentration, the higher was the ceric ion consumption.
Pervaporation separation of aqueous mixtures using crosslinked poly(vinyl alcohol), I. Characterization of the reaction between PVA and amic acid
Authors: Yeom C. K. , Huang R. Y. M.
Published: April 2003

For the purposes of new membrane material development for pervaporation separation based on crosslinked polyvinyl alcohol (PVA), IR spectroscopy and DSC were used to characterize the crosslinking reaction and the imidization of the (PVA)‐amic acid system. The IR spectra and the thermal analysis were performed on specimens that had been reacted for several different times at 150°C. The crosslinking reaction between the hydroxy groups of PVA and the carboxylic groups of amic acid was faster than the imidization of the amic acid. The best reaction times were about 30 min for the crosslinking reaction and 90 min for the imidization. The effects of the reaction time and the amic acid content on the thermal and mechanical properties have also been investigated.
Effect of frequency and temperature on dielectric properties of polystyrene at microwave frequencies
Authors: Chaki Tapan K. , Khastgir Dipak K.
Published: April 2003

Ambient dielectric measurements as functions of frequency in X‐band microwave region have been made on solid samples of polystyrene. Effects of temperature (−120 to +160°C) at three different frequencies have also been studied. The measurement technique applied based on short‐circuited waveguide method of Roberts and von Hippel modified by Dakin and Works for low loss and medium loss samples. Two different types of relaxations are identified originating from main chain motion, wagging, and rotational motions of pendent phenyl group. Intrinsic activation energy for polystyrene molecule, dipole moment per repeat unit, and the average apparent energy of a polystyrene molecule associated with its induced transient dipoles have also been calculated and the data so obtained are explained and compared with standard literature.
Polyurethane‐crosslinked epoxy resins. II. Compatibility and morphology
Authors: Han J. L. , Tseng S. M. , Mai J. H. , Hsieh K. H.
Published: April 2003

The polyurethane(PU)‐crosslinked diglycidyl ether of bisphenol A (DGEBA) was prepared from the reaction of the pendent secondary hydroxy group in DGEBA with the isocyanate‐terminated group present in the PU prepolymer. Though the PU acted as a crosslinking agent for the DGEBA, the morphology and dynamic mechanical behaviour of these PU‐crosslinked DGEBA could be different among themselves depending on the type and molecular weight of polyols employed in the PU. There was no significant shift in the loss modulus (E″) peaks of the DGEBA crosslinked with the polyester‐type and polyether‐type polyurethanes, but the intensity of the E″ peaks increased as the polyester‐type PU employed. The morphology of this polyester‐type PU‐crosslinked DGEBA exhibited a homogeneous one‐phase system, while the DGEBA crosslinked with the polyether‐type PU showed a two‐phase morphology with the PU particles dispersed in DGEBA matrix.
Study of polymer‐polymer complex formation involving phenolic copolymer, non‐ionic polymers, and polyelectrolytes
Authors: Chatterjee S. K. , Ghosh S. , Chatterjee N.
Published: April 2003

Multicomponent interpolymer complexes have been prepared by interacting a phenolic copolymer of known composition with several non‐ionic homopolymers, e.g., PVP, PEO, PVA and polyelectrolytes, such as PAA and PEI. The formation of these complexes has been studied by several techniques, such as viscometry, potentiometry, conductometry, and IR spectra. A scheme has been presented to explain the mode of interaction of the various component polymers.
ABA block copolymers without tapering by isokinetic living anionic polymerization in a series of stirred tank reactors
Authors: Hesterwerth D. , Bandermann F.
Published: April 2003

Equations for the molecular weight distribution and the average molecular weights of a living anionic polymerization with very rapid or slow initiation are presented for a series of stirred tank reactors. It is shown that polydispersity of the polymer in the last vessel of a cascade takes for nearly complete conversion of monomer then a minimum, when the reaction is performed isokinetically with concern to monomer conversion, i.e. when monomer conversion in each vessel of a cascade of n tanks is 1/n. Now, polydispersity of the polymer in the mth vessel of the cascade (1 ≤ m ≤ n) is Dm = 1 + 1/m. Values of all systems variables needed for isokinetic control of the polymerization may be precalculated from kinetic models. For vessels of equal size and with equal residence times reaction temperature is suggested as control variable increasing stepwise from vessel to vessel. The proposed procedure was checked for the systems styrene/n‐butyllithium/toluene, styrene/s‐butyllithium/benzene, and isoprene/s‐butyllithium/n‐heptane. A satisfying agreement between calculated and measured values of the objectives monomers conversion, number average molecular weight, and polydispersity was found. It is proposed to use the described procedure for the preparation of ABA block copolymers with negligible tapering between the blocks by living anionic polymerization in a series of stirred tank reactors.
Sequences in copolymers studied by high‐mass oligomers in pyrolysis‐field ionization mass spectrometry
Authors: Plage B. , Schulten H.‐R.
Published: April 2003

Poly(acrylonitrile), butadiene‐acrylonitrile copolymer, and styrene‐acrylonitrile copolymers with acrylonitrile contents between 8 and 50 mol‐% have been investigated by pyrolysis‐field ionization mass spectrometry. Molecular ions of thermally‐formed oligomers containing up to 16 monomeric subunits were recorded in the mass range 50 to 1200 g/mol. With the butadiene‐acrylonitrile copolymer, the relative abundances of signals due to oligomers with the same total number of monomeric subunits is close to the random distribution of these subunits in the polymers. In contrast, with the styrene‐acrylonitrile copolymers the acrylonitrile contents indicated by relative abundances are too high with all samples. On the other hand, the mass spectra confirm that styrene‐acrylonitrile sequences are more abundant than expected from random distribution of the monomeric subunits, whereas the relative abundances due to oligomers containing styrene‐styrene or acrylonitrile‐acrylonitrile sequences are significantly lower than expected for random systems. These results can be explained by the enhanced stability of styrene‐acrylonitrile diads.
Dibenzoyl peroxide as an initiator of radical polymerizations: Reactions of the benzoyloxy radical with monomers
Authors: Bevington John C.
Published: April 2003

Experimental methods for comparing the reactivities of unsaturated substances towards the benzoyloxy radical are considered. Results for various monomers are discussed. It is shown that some substances show high reactivity towards the radical although they do not ordinarily give homopolymers or act as comonomers; they include β‐methylstyrene, stilbene and related substances, and 1.4‐diphenylbuta‐1, 3‐diene.
GEORDNETE EPOXIDNETZWERKE AUS 4‐GLYCIDYLPHENYL‐4‐GLYCIDYL‐BENZOAT und 3‐ BZW. 4‐AMINOPHENYL‐4‐AMINOBENZOAT
Authors: Kirchmeyer Stephan , Karbach Alexander , Müller Hanns‐Peter , Meier Helmut‐Martin , Dhein Rolf
Published: April 2003

The introduction of mesogenic groups in main‐ and sidechains of epoxy thermosets results in an ordered multiphase network with cellular structure, if gelation occurs below the maximal cure temperature Tmax. Tmax is individual for a given combination of monomers. The multiphase network consists of relatively soft anisotropic cell nuclei and hard isotropic cell walls. If gelation occurs above Tmax single phase networks are obtained. The size of the cell nuclei strongly depends on the used monomers and varies up to two orders of magnitude. The multiphase structure was found to have no impact on the tensile elastic modulus.
Dimensions‐ und Dichteänderung von Polymidformteilen durch Wasseraufnahme
Authors: El Sayed A. , Eckert A.
Published: April 2003

Additive in Polyamiden wie Nukleierungsmittel oder Verstärkungsmittel beeinflussen das Kristallisations‐ und Erstarrungsverhalten. Während der Herstellung von Probekörpern bilden sich morphologische Strukturen, die die Verarbeitungsschwindung, den linearen Ausdehnungskoeffizienten und die Dimensionsänderung während der Wasseraufnahme beeinflussen. Anhand der Volumenänderungen wird der Zusammenhang zwischen der Wasseraufnahme und der Dimensionsänderung in allen drei Raumrichtungen verständlich dargestellt.
Synthesis of macromonomers of poly(2,6‐dimethyl‐1,4‐phenylene oxide)
Authors: Wicker Michael , Heitz Walter
Published: April 2003

Poly(2,6‐dimethyl‐1,4‐phenylene oxide) with exactly one functional endgroup was synthesized by oxidative polymerization, halogen substitution polymerization, and by phase transfer catalysis. Reaction with 4‐vinylbenzoyl chloride resulted in a quantitative conversion to a macromonomer as shown by GPC and endgroup analysis. The macromonomer is a glassy material with a Tg from 150 to 190°C depending on the molecular weight.
Tensile strength of thermoplastic blends and composites
Authors: Andradi L. N. , Löwenhaupt B. , Haufe A. , Hellmann G. P.
Published: April 2003

Failure of purely thermoplastic blends has so far, in contrast to that of thermoplastic‐elastomeric blends, not been studied extensively. In this investigation, the tensile strength of the brittle thermoplastics polymethylmethacrylate and polystyrene, of their random copolymers, their blends, and also of blends of polymethylmethacrylate with the copolymers was measured. The polymers behave all mechanically similarly, but the blends assume all degrees of miscibility and coarseness of phase morphology. For comparison with the blends, also macroscopic composites were tested.
Chain length effect of alkenyl succinic anhydride on thermal and mechanical properties of the cured epoxy resins
Authors: Jung Jin Chul , Lee Sung‐Koo , Lee Kwang‐Sup , Choi Kil‐Yeong
Published: April 2003

As epoxy curing agents three alkenyl succinic anhydrides (ASA) with varying side chain length (2‐octenyl, 2‐dodecenyl and 2‐hexadecenyl succinic anhydride) were prepared by the ene synthesis and thermal and mechanical properties of a bisphenol A epoxy resin cured with the ASA's were measured. With increase in the side chain length of the ASA the Tg, the tensile strength and the impact strength decreased. All the cured samples exhibited excellent transparency and flexibility.
UNTERSUCHUNGEN ZUR ALKALIBEHANDLUNG VON CELLULOSEFASERN. TEIL 1. INFRAROTSPEKTROSKOPISCHE UND RÖNTGENOGRAPHISCHE BEURTEILUNG DER ÄNDERUNG DES ORDNUNGSZUSTANDES
Authors: Richter Ute , Krause Thomas , Schempp Walter
Published: April 2003

Die als Folge einer Behandlung mit Natronlauge im Konzentrationsbereich von 0–50% NaOH eintretenden Veränderungen des Ordnungszustandes verschiedener Cellulosefasern (Holzzellstoffe und Baumwollinters) wurden infrarotspektroskopisch und röntgenographisch verfolgt. Die Bestimmung eines IR‐Index als Relation der Peakflächen im Wellenzahlenbereich von 1370 und 670 cm−1 gestatteten eine mit geringem Aufwand durchzuführende Bestimmung insbesondere der im Gebiet der Natronlaugenkonzentrationen von 7.5–15%iger Lauge signifikant abfallenden Kristallinität. Weitaus aufwendigere röntgenographische Messungen des Kristallinitätsindex bestätigen die infrarotspektroskopisch erhaltenenen Befunde. Es ergibt sich die Möglichkeit, anhand gewisser Unterschiede im Verlauf der IR‐Indexkurven Schlüsse in bezug auf die Aktivierungsfähigkeit einzelner Faserproben zu ziehen.
ZUM EINFLUSS DES MOLEKULARGEWICHTS AUF DIE MAKROSKOPISCHE GRENZFLÄCHE BINDENAHT
Authors: Mennig G.
Published: April 2003

Knit lines or weld lines are observed in plastics processing, e.g. injection moulding and extrusion, when separated streams of melt are rejoined. The result is quite often a visible mark of reduced mechanical strength. The investigation deals with the influence of molecular weight on knit line strength. Injection moulded test specimens from different polymethyl methacrylates show that the relative knit line strength decreases with increasing molecular weight. However, for constant viscosity, i.e. same mobility of macromolecules, the knit line strength remains constant. The observations coincide nicely with the general understanding with the mechanism of interdiffusion.
ZERSTÖRUNGSFREIE PRÜFUNG VON POLYMEREN MITTELS PHOTOTHERMISCHER MEßMETHODEN 1. DIE PHOTOTHERMISCHE INFRAROTRADIOMETRIE
Authors: Eickmeier Achim , Bahners Thomas , Schollmeyer Eckhard
Published: April 2003

Es wird eine Einführung in die als photothermische Meßmethoden bezeichneten Absorptionsspektroskopien gegeben und Experimente zur Prüfung und Vermessung von polymeren Werkstoffen mit der photothermischen Infrarot‐Radiometrie beschrieben. Der Vergleich zwischen einem HeNe‐Laser und einem UV‐Excimerlaser als Primäranregung zeigt, daß es nur durch den Einsatz der UV‐Lichtquelle möglich ist, transparente Polymerproben photothermisch zu untersuchen. So konnten unter Verwendung eines KrF‐Excimerlasers empfindliche Dickenmessungen an PETP‐Folien durchgeführt werden.
A structure rheological study with poly (oxyethylene)
Authors: Schurz J. , Pfragner J. , Abd‐Elrahim F. M. , Moustafa A. B.
Published: April 2003

Four samples of poly(oxyethylene) dissolved in water have been studied rheologically. Flow curves have been obtained for different molecular mass and concentration. From no the mass of network strand, the apparent chain element and the penetration hindrance have been obtained. The polymer turns out to form in water entanglement network solutions with somewhat hindered penetration.
Macroporous membranes. 3. Properties of macroporous membranes synthesized from glycidyl methacrylate, ethylene dimethacrylate and alkyl‐ or hydroxyalkyl methacrylate
Authors: Hradil J. , Jelinkova M. , Ilavsky M. , Svec F.
Published: April 2003

A series of macroporous membrances composed either of glycidyl methacrylate and ethylene dimethacrylate with an addition of other monomer chosen from a group comprising 2‐hydroxyethyl methacrylate, butyl methacrylate, octyl methacrylate or dodecyl methacrylate, or of a copolymer of 2‐hydroxyethyl methacrylate and ethylene dimethacrylate were synthesized and their properties were determined. The addition of a third monomer changes the porous properties only when the concentration of the monomer in the polymerization feed is rather high. The presence of bulkier alkyl side chains in a polymer matrix raises hydrophobicity and reduces the water regain while the strength of the membrane increases.
RINGÖFFNENDE METATHETISCHE POLYMERISATION (ROMP) VON 5‐CYANO‐2‐NORBORNEN
Authors: Thorn‐Csányi Emma , Harder Christian
Published: April 2003

Die ringöffnende metathetische Polymerisation (ROMP) von 5‐Cyano‐2‐norbornen wurde unter Einsatz von Wolframhexachlorid, Wolframoxidterachlorid, Bis(dichloralkoxo)wolframtetrachlorid und Bis(dichloralkoxo)wolframoxiddichlorid als Übergangsmetallkomponente untersucht. Als Cokatalysatoren dienten Methylaluminoxan, Diethylaluminiumethoxid, Tetraisobutyldialuminoxan und Tetrabutylzinn. Als Lösungsmittel wurden Toluol, Chlorbenzol und Dichlormethan verwendet. Die Konzentration der Wolframkomponente lag im Bereich 5 × 10−4 − 5 × 10−3 mol/l. Unter den geprüften Katalysatoren erwies sich Wolframhexachlorid in Verbindung mit Diethylalumiumethoxid als der geeignetste. Mit diesem System verlief die Polymerisation auch bei großen Monomer/Wolfram‐Verhältnissen (10200 :1) hochselektiv und führte zu großen Umsätzen (≥82%).
Strength retention of self‐reinforced, absorbable polyglycolide rods in hydrolytic environment
Authors: Törmälä Pertti , Mikkola Heta‐Maija , Vasenius Jarkko , Vainionpää Seppo , Rokkanen Pentti
Published: April 2003

Absorbable polyglycolide suture fibers were sintered with the compression molding techniques to cylindrical rods at temperatures between 205°C and 232°C for 3–5 min with final pressures of 50–80 N/mm2. The cylindrical rods had nominal diameters between 1.5–4.5 mm and a length of 50 mm. The initial bending moduli and the initial bending strengths of the rods were between 9–15 GPa and 220–430 MPa, respectively. The shear strengths of the rods were between 165–255 MPa.

The hydrolytic loss of mechanical strength of the above self‐reinforced, absorabable polyglycolide rods were studied in phosphate buffer at 37°C and 77°C.

It was found that the rate of strength loss decreases with the increasing diameter of the rods. On the other hand, the rate of strength loss increases when the temperature of the buffer solution is raised. The strength, retention time at 37°C was between 7–10 weeks showing that the loss of mechanical strength of self‐reinforced polyglycolide rods occurs more rapidly in vivo than in vitro.
Kinetics of radical polymerization, LIII. The absolute rate constants in the radical polymerization of ethyl acrylate
Authors: Tüdős F. , Nagy A. , Földes‐Berezsnich T.
Published: April 2003

The dependence of dilution on the chain propagation and termination rate constants was investigated in the polymerization of ethyl acrylate in benzene solution at 50°C, with the rotating sector method. The errors of the above rate constants were determined and, by our method applied to decrease these errors, the errors of the propagation rate constant was reduced to its half value. By the application of our earlier results in polymerization kinetics, we found that in this system the chain propagation step is exclusively responsible for the solvent effects observed. Our experimental results can be quantitatively described in terms of the hot redical theory.
Dielectric and optical properties of liquid crystalline side chain polymers. A MNDO‐analysis
Authors: Birenheide Richard , Budesheim Klaus W. , Wendorff Joachim H.
Published: April 2003

Semiempirical quantum mechanical MNDO‐calculations were performed on side chain liquid crystalline polymers to predict their electronic properties and thus their anisotropic dielectric and optical properties. These predictions are compared with the corresponding experimental results. The conclusion is that the predictions are sufficiently accurate, which suggests to use such methods for screening potentially interesting polymer liquid crystals prior to synthesizing them.
Zur Beschreibung von Copolymeren aus 3 oder mehr Monomeren
Authors: Wittmer P. , Hungenberg K.‐D.
Published: April 2003

Die Beschreibung von Copolymeren aus mehr als 2 Comonomeren auf algebraischem Weg führt zu nur schwer handhabbaren Gleichungen. Dagegen ist die Beschreibung mit Hilfe von Markov‐Ketten sehr einfach. Im einzelnen wird die Berechung der Copolymerenzusammensetzung, Sequenzhäufigkeiten, Sequenzlängenverteilungen, mittleren Sequenzlängen sowie der Häufigkeiten von Diaden diskutiert.
Involvement of the impregnation in the degree of polymerization of cellulose during soda pulping of sugar cane bagasse
Authors: Soubelet Oscar , Maximino Mirta , Marx‐Figini Marianne
Published: April 2003

A comparative study had been carried out on the behaviour of the degree of polymerization (DP) of sugar cane bagasse during different times of digestion (soda pulping) with and without previous impregnation. Determination of the average DP (DPη) and its distribution show that the impregnated materials undergo degradation during the digestion, what in contrary is not to observe when digestion is carried out without previous impregnation. It is supposed that the impregnation alters the chemical structure of the cellulose, facilitating thus the degradation during digestion. From the distribution curves arises furthermore, independent from impregnation or not and independent from the digestion time, a very pronounced maximum (about 25 wt.‐% of total mass) at DP < 150 belonging to a non‐cellulosic polysaccharide present in the sugar cane bagasse, which is removed neither by digestion nor by nitration.
Polymer solid electrolytes based on ethylene oxide copolymers
Authors: Florjańczyk Zbigniew , Krawiec Włodzimierz , Wieczorek Władysław , Przyłuski Jan
Published: April 2003

Ethylene oxide was copolymerized with propylene oxide, epichlorohydrin or styrene oxide at various monomer feed compositions, using partially hydrolyzed organoaluminium compounds as catalysts. The copolymers obtained after doping with NaI form highly conductive polymeric electrolytes. Complex impedance measurements show relaxation semicircles much less depressed than in semicrystalline electrolytes based on Poly(ethylene oxide). The maximum values of the room temperature conductivity for each kind of copolymer containing electrolytes are higher than those for the pristine poly(ethylene oxide)‐Nal system. The highest value, equal to 2.6 · 10−5 S/cm at 25°C, was found for poly(ethylene oxide‐co‐propylene oxide) containing 33 mol‐% of propylene oxide monomeric units.
Azo dyes based on phenolic oligomers
Authors: Patel Hasmukh S. , Lad Babu D.
Published: April 2003

A series of new oligomeric disperse and acid azo‐phenolic dyes were prepared by coupling various aromatic diazonium salts to phenol‐formaldehyde (PF), m‐cresol‐formaldehyde (CF) and resorcinol‐formaldehyde (RF) oligomers. They were characterized in terms of their softening points, colour, solubility, IR and UV‐Vis spectra and thermogravimetric properties. Their dyeing on polyester, nylon and wool resulted in yellow, orange, and brown to red shades with good to excellent light‐fastness and wash‐fastness properties.
Synthesis and characterization of some 2,4′‐dibenzyldiisocyanate ionic polymers, 7. Photochromic behaviour of ionenes with viologen units
Authors: Buruianǎ E. C. , Diaconu I. , Buruianǎ T. , Grigoriu G. E. , Caraculacu A.
Published: April 2003

The Photochromic properties by UV and laser irradiation of cationic polyurethanes with viologen groups introducted by Menschutkin reaction were studied and poly(vinylalcohol) was used as matrix.
Impact behaviour and morphology of rubber‐modified epoxy resins
Authors: Pucciariello Rachele , Villani Vincenzo , Bianchi Nadia , Braglia Roberto
Published: April 2003

In the present work the impact behaviour at high speed of rubber‐modified epoxy resins has been investigated. Impact‐tension measurements have been performed to evaluate the toughness of different systems. A detailed post‐failure observation of the fracture surfaces has been made through scanning electron microscopy (SEM). A combination of a solid fluorinated rubber with the generally used carboxy‐terminated butadiene‐acrylonitrile rubber (CTBN) was found to be very effective.

A correlation was tempted between the observed fracture behaviour and the bulk morphology, examined by transmission electron microscopy (TEM).
Crystallinity of polyethylene measured by density, DSC, and raman spectroscopy. A comparison
Authors: Földes Enikő , Keresztury Gábor , Iring Margit , Tüdős Ferenc
Published: April 2003

In this work three different techniques were used to determine the crystallinity of polyethylene. After different pretreatment HDPE, LLDPE, and LPDE samples were investigated by density measurements, differential scanning calorimetry, and Raman spectroscopy. The results were compared and relationships were estabilished between the values measured by the different methods.
Untersuchung des einflusses molekularer parameter auf morphologie und eigenschaften von polyethylenen niedriger dichte
Authors: Braun Dieter , Rätzsch Manfred , Fiedler Peter , Weber Günter , Hofmann Heinz , Gutschalk Bernd
Published: April 2003

Am Beispiel von PE‐LD‐Sorten und der durch präparative Fraktionierung gewonnenen Modellsubstanzen (Fraktionen im Molmassenbereich M̄w = 1,2 – 390·104 g/mol) wurden umfangreiche Untersuchungen zur Struktur‐Eigenschaftsproblematik durchgeführt.

Untersucht wurden die Korrelationen von M̄w mit 15 physikalischen und anwendungstechnischen Parametern unter Berücksichtigung der Reaktionsmechanismen bei der Herstellung von PE‐LD im Rohr‐ und Rührautoklavreaktor, die zur Bildung der sogenannten primären Strukturparameter M̄n,M̄w, Molmassenverteilung, Kurzkettenverzweigung und Langkettenverzweigung führen. Bei der Interpretation der Ergebnisse wurden u. a. auch die morphologischen Gegebenheiten berücksichtigt, die im Zusammenhang mit den molekularen Parametern für bestimmte M̄w‐Bereiche starke Ande‐rungen bzw. Sattigungsbereiche für die physikalischen und anwendungstechnischen Eigenschaften erkennen lassen.