bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction of amphiphilic polymers with model membranes
Authors: Decher Gero , Kuchinka Ellen , Ringsdorf Helmut , Venzmer Joachim , Bitter‐Suermann Dieter , Weisgerber Christoph
Published: April 2003

The lipid bilayers of cell membranes are usually connected to two types of biopolymers: the cytoskeleton and the glycocalix. These structures are not only responsible for the stabilization of the lipid bilayer, they also alter the surface properties of the cells. Among the various attempts to mimick membrane properties using polymeric systems(1), one method is the fixation of amphiphilic polymers via hydrophobic anchor groups to lipid bilayers. In the experiments reported here the influence of amphiphilic polymers on the morphology of giant unilamellar liposomes has been investigated. Therefore a series of amphiphilic polyvinylpyrrolidone and dextran derivatives has been synthesized. The fixation of these polymers to the liposomal membranes could be shown with a fluorescence‐labelled derivative by using epifluorescence microscopy. The polymer‐membrane interaction caused by the insertion of the anchor groups leads to drastic morphological changes in this model membrane system. The exclusive interaction with the outer membrane of multilamellar liposomes could be demonstrated by freeze fracture electron microscopy. In addition, the anchoring of a natural capsular polysaccharide in liposomes has been proven by immunofluorescence. In these experiments, also a clustering (patching) of the antigen caused by the binding of the antibody could be observed.
Liquid crystals in biological systems
Authors: Hoffmann Siegfried
Published: April 2003

Notwithstanding their more common beginnings, liquid crystals and molecular biology developed mainly parallel and independently during the last one hundred years.

Molecule‐phase relationships on the one and complex static‐dynamic treatments on the other hand seem to forward mutually integrative views in our days.

Biomesogen approaches will deepen our insights into the spatio‐temporal coherences of biological systems. They might contribute significantly to the understanding of life processes.
Preparation and characterization of microdisperse bioavailable carotenoid hydrosols
Authors: Horn Dieter
Published: April 2003

The application of carotenoids as natural additives in various water‐based or water‐compatible formulations for the pigmentation of foods and feeds is seriously hampered by their insolubility in aqueous systems.

Therefore, in order to develop the full potential of colour strength and to achieve a high degree of bioavailability during gastro intestinal passage, the coarse crystalline material has to be transformed into a microdisperse state.

Exemplified with β‐carotene, a novel non‐mechanical process is described that transforms the carotenoids into a colloidal hydrosol characterized by an average particle size of about 0.1 μm.

The process is based on the preparation of a transient high temperature solute state of the carotenoid in a water‐miscible solvent, coupled with succeeding rapid aqueous precipitation in the presence of a stabilizing polymer colloid. The obtained hydrosols are characterized by photon‐correlation‐spectroscopy(size), and microelectrophoresis(colloidal stabilization).

The bioavailability was tested by monitoring plasma levels of β‐carotene in veal calves.
Bioresorbable polymers for temporary therapeutic applications
Authors: Vert M.
Published: April 2003

Polymer science is mature enough to allow one to think about tailor‐making macromolecular compounds aimed at interacting purposely with living systems. Reasons for developing bioresorbable polymers for temporary therapeutic applications are discussed with respect to property adjustments and economical factors. The field of the applications is first described and guidelines for tailor‐making multimeric macromolecules with desired properties are presented. The approach led to focuss investigations on poly(α‐hydroxy acids) and functional poly(β‐hydroxy acids) derived from natural hydroxy acids, namely lactic, glycolic and malic acids. Physical, mechanical and biological properties of some corresponding polymers and copolymers are presented. Last but not least, examples of applications currently investigated are recalled.
Polymere in der diagnostik
Authors: Batz Hans‐Georg , Hopp Herbert , Mang Thomas , Schmidt Brigitta
Published: April 2003

Diagnostics are e. g. reagents or combinations of reagents or measure bloodcomponents down to concentrations of 10−15 mol/1 in reproducable form. To achieve this target diagnostics have to fullfill special requirements in purity, uniformity, producibility and reproducibility. These requirements are also valid for integrated polymers and plastics. Examples of the application of polymers and plastics in diagnostics are e. g. materials for the blood‐plasma‐separation, the stabilization of proteins, solid phases in immunoassays as reagent tubes, microtiterplates and latexparticles.

Reciprocal actions between polymers, plastics, polymer additives, blood and bloodsubstances like proteins in diagnostic tests can be seen as indications to similar effects by the intracorporeal applications of plastics in surgery and in general for contacts of natural materials with plastics, as usual in the foodpacking.
The application of immobilized affinity ligands in high performance liquid chromatography
Authors: Josić Dj. , Reutter W. , Krämer D. M.
Published: April 2003

Using Eupergit, a synthetic resin, as an example, the necessary characteristics of a support for high performance affinity chromatography (HPAC) are demonstrated. To such a support different ligands can be immobilized and used for the separation of biopolymers.

From the range of possible applications a few examples are chosen. Immunoglobulins are isolated in one step by protein A‐HPAC, the purified antibodies are immobilized and applied to immunoaffinity‐HPLC for the isolation of corresponding antigens. Concanavalin A‐HPAC of membrane proteins was chosen to represent chromatography with immobilized lectins. Antithrombin could be isolated from human plasma by the use of immobilized heparin. HPAC has the advantage of affinity chromatography, which is above all highly specific. As the support is resistant to high pressure and has well defined microparticles with a particular pore size, it provides a much higher yield at considerable flow rates. The handling of materials like this is simpler, the separation of the sample is quicker and can be reproduced more easily.
Polymers for the immobilization of whole cells and their application in biotechnology
Authors: Klein J. , Kressdorf B.
Published: April 2003

Immobilization of whole cells has become an efficient tool for biosynthesis, biotransformation and analysis. High cell density, high operational stability, easy handling, propably in continuous systems, and multiple reuse are important advantages of immobilized cells. In comparison to other methods like adsorption, crosslinking and encapsulation, the entrapment within a polymeric network is the most widely applied technique in heterogeneous biocatalysis. For immobilizing mammalian cells nearly exclusively the adsorption onto micorcarriers is used. Requirements for the polymers to be used in such immobilized cell systems are discussed in detail.
Morphology and supermolecular structure of the polymer system PA‐6/PMA
Authors: Janicki Jarosław , Włochowicz Andrzej
Published: April 2003

The results of investigations of the supermolecular structure of the mixture of a semicrystalline polymer polyamide‐6 (PA‐6) and of an amorphous one, poly(methacrylic acid) (PMA), are presented. The determination of the supermolecular structure was realized using the correlation functions and the interface distribution functions calculated from SAXS patterns. It was stated that the introduction of poly(methacrylic acid) results in a transformation of the γ‐type crystalline structure into the α‐type structure. Until the PMA content is less than 46%, the blend has a lamellar structure, and an increase in the PMA content causes an increase in the long period. PMA and the amorphous phase of PA‐6 form a homogeneous phase, there are no microdomains of PMA.

An increase in the PMA content results in a decrease of the crystallinity index. Simultaneously, the thickness of the transition layers between the crystalline regions and the phase composed of PMA and of the amorphous phase of PA‐6 increases. When the content of PMA is large, the lamellar structure disappears.
Mechanische Eigenschaften von Polyesterfasern bei kurzzeitiger Zugbeanspruchung, 1. Aufbau eines Meßplatzes für schnelle Zugbeanspruchung
Authors: Beier Manfred , Schollmeyer Eckhard
Published: April 2003

Kraft‐Dehnungs‐Graphen von Filamentgarnen für die Dehngeschwindigkeiten zwischen 10−1 und 105%/s werden ermittelt. Für die niedrigen Dehngeschwindigkeiten bis 10%/s wird eine übliche Zugprüfmaschine benutzt, die höheren Dehngeschwindigkeiten werden mit einer Fallschlagapparatur durch Variation der Fallhöhe und der Fadenlänge erreicht.

Aufgrund der hohen Dehngeschwindigkeit und der Meßzeiten bis minimal 10−4 s sowie der Variation der Fallhöhe zwischen 0,6 und 166 cm treten Fehler auf, die eingehend diskutiert werden.
Mechanische Eigenschaften von Polyesterfasern bei kurzzeitiger Zugbeanspruchung, 2. Verformungsgeschwindigkeitsabhängige Kraft‐Dehnungs‐Diagramme von Polyester‐Multifilamentgarn
Authors: Beier Manfred , Schollmeyer Eckhard
Published: April 2003

Untersucht werden Polyethylenterephthalat (PETP)‐Multifilamentgarne mit unterschiedlicher thermischer Vorgeschichte.

Die Kraft‐Dehnungs‐Kurven für die Dehngeschwindigkeit von 0,1 bis 100 000%/s zeigen, daß die Höchstzugkraft mit der Dehngeschwindigkeit zunimmt und die Höchstzugkraftdehnung abnimmt. Für die Garne mit unterschiedlicher thermischer Vorgeschichte bestehen jedoch Unterschiede, was die Änderung der Höchstzugkraftund Höchstzugkraftdehnungswerte mit der Dehngeschwindigkeit betrifft. So weist ein spannungslos thermisch behandeltes Material eine geringere Änderung der Höchstzugkraft mit steigender Dehngeschwindigkeit auf als ein bei gleicher Temperatur, aber unter Spannung thermofixiertes Material. Die Höchstzugkraftdehnungswerte zeigen dagegen ein umgekehrtes Verhalten. Mit wachsendem Einfluß der Dehngeschwindigkeit auf die Bruchkraft nimmt das Verhältnis von Höchstzugkraft zu Höchstzugkraftdehnung stärker zu.

Die Anfangssteigung, d. h. der Anfangsmodul der K‐D‐Kurven des Fadenmaterials, nimmt für alle Fixierspannungen und ‐temperaturen mit der Dehngeschwindigkeit zu. Das lokale Minimum der ersten Ableitung der K‐D‐Kurven (lokales Modulminimum) verlagert sich mit zunehmender Dehngeschwindigkeit zu höheren Modulwerten, die Lage des Minimums als Funktion der Dehnung bleibt jedoch konstant.
DSC studies on melt crystallized, drawn and fuming nitric acid oxidized polyethylene
Authors: Akar Ahmet , Aydoǧan A. Cevdet , Zaim Ömer , Tinçer Teoman
Published: April 2003

Melting, recrystallisation and remelting of undrawn and drawn linear polyethylene with different molecular weight were studied by differential scanning calorimetry before and after oxidation with nitric acid.
Eine Studie über den Pyrolysevorgang bei organischen Bindemittelsubstanzen für die Herstellung von Kohlenstoffmaterialien
Authors: Popovska Nadeshda
Published: April 2003

Mittels Thermo‐ und Röntgenstrukturanalyse wird eine vergleichende Untersuchung des Pyrolysevorganges und der Mikrostruktur des aus zwei Gruppen organischer Bindemittel und deren Mischungen gewonnenen Koksrückstandes durchgeführt. Gruppe I umfaßt reine und mit Hydrolyselignin gefüllte Resol‐ und Novolak‐Phenol‐Formaldehydharze und Gruppe II Steinkohlenpech und ‐teer. Es wird festgestellt, daß sich die Mischungen Novolakharz‐Pech, Resolharz‐Teer und Resolharz‐Hydrolyselignin beim Erhitzen nicht wie mechanische Gemische verhalten und eine erhöhte Ausbeute an Koksrückstand liefern. Weiterhin wird gefunden, daß die integrale Endtemperatur der Pyrolyse (T) dieser Substanzen als quantitatives Maß für die Ausbeute an Koksrückstand im Anschluß an die Carbonisierung der Proben dienen kann.
Chemical modification of rice starch via its reaction with acrylamide
Authors: Haggag K. , Kantouch F. A. , El‐Thalouth I. Abd
Published: April 2003

Rice starch was carbamoyl ethylated via its reaction with acrylamide in presence of sodium hydroxide under a variety of conditions. Variables included the concentration of acrylamide, the reaction temperature and the preparation medium. It was found that the extent of the reaction increases by increasing the acrylamide concentration. The temperature plays a dominant role in the extent of the reaction. Carbamoyl ethylated starches are water soluble and can be precipitated by ethyl alcohol. Printing pastes thickened with carbamoyl ethyl starch samples are characterized by non‐Newtonian thixotropic behaviour. At a constant rate of shear, the values of the apparent viscosity increase as the nitrogen content of the product increases. Furthermore, increasing the reaction temperature is accompanied by a substantial decrease in the apparent viscosity at a constant rate of shear.
Water absorption characteristics of vinyl alcohol/vinyl propionate copolymers with different microstructure
Authors: Arranz F. , Sánchez‐Chaves M. , Gómez‐Moñux M.
Published: April 2003

Vinyl alcohol/vinyl propionate (VAL/VP) copolymers with different microstructure were prepared by two different methods, i.e. partial alkaline hydrolysis of poly(vinyl propionate) and by partial esterification of poly(vinyl alcohol). 13C‐NMR results show that vinyl propionate units have an alternating tendency in VAL/VP copolymers prepared by esterification and a block distribution in VAL/VP copolymers when they are prepared by hydrolysis. The water absorption characteristics of VAP/VP copolymers have been studied. VAL/VP copolymers with a block sequence distribution exhibit a higher water absorption ability as compared with VAP/VP copolymers with a random sequence distribution and similar chemical composition. These results can be interpreted considering the formation of intramolecular hydrogen bondings as well as due also to steric hindrances effects. Sodium salicylate release studies from VAL/VP copolymers show that release is faster in VAL/VP copolymers prepared by hydrolysis according to its higher swelling ability in water.
4,4′‐carbo(4,4′‐bismaleimido phenoxy)diphenyl silane: Synthesis and characterization
Authors: Varma I. K. , Chander K. , Anand R. C.
Published: April 2003

The paper describes the successful synthesis of silicon containing bismaleimide resin 4,4′‐carbo(4,4′‐bismaleimido phenoxy)diphenyl silane. The char yield of the bismaleimide resin in N2 atmosphere was found to be 55% at 800°C. Chain extension of bismaleimide with 4,4′‐diamino diphenyl sulfone reduced the char yield and thermal stability.
Mechanische eigenschaften von polyesterfasern bei kurzzeitiger beanspruchung, 3. Konstruktion von relaxations‐ und retardations‐masterkurven von polyester‐multifilamentgarn
Authors: Beier Manfred , Schollmeyer Eckhard
Published: April 2003

Von Polyethylenterephthalat (PETP)‐Multifilamentgarnen mit unterschiedlicher thermischer Vorgeschichte wurden Kraft‐Dehnungs‐Kurven mit den Dehngeschwindigkeiten 0,1 bis 100 000%/s ermittelt. Diese lassen sich zu Relaxations‐ und Retardationskurven über sieben Zeitdekaden umrechnen. Durch Superponieren von Relaxationsfunktionen für unterschiedliche Dehnungen bzw. Retardationsfunktionen für unterschiedliche Fadenzugspannungen werden Relaxations‐ und Retardationsfunktionen bis 21 bzw. 13 Zeitdekaden bestimmt, die sich in vier Bereiche unterteilen lassen, denen folgende Strukturveränderungen zugeordnet werden können:

Bereich 1: sofort erholbare, quasielastische Deformation mit Relaxationszeiten kleiner 1 bis 10 s,

Bereich 2: irreversible Deformation, Verfestigung, mit Relaxationszeiten zwischen 10 und 105 s,

Bereich 3: elastisches Verhalten des physikalischen Netzwerkes mit Relaxationszeiten zwischen 105 und 107 s und

Bereich 4: Umbau und Zerstörung des Netzwerkes mit Relaxationszeiten zwischen 107 und 1016 s.
Application of a mathematical model for the polyesterification process based on mixtures of fumaric acid and adipic acid without catalyst
Authors: Simitzis Johannis
Published: April 2003

The production of unsaturated polyesters based on mixtures of fumaric acid and adipic acid for different proportions without added catalyst was studied. The progress of the polyesterification was followed by determining the amount of water produced during the reaction. The kinetic parameters (reaction order n, activation energy E, frequency factor k0) of the polyesterification were determined and it was found out that n = 3 in all cases, while E and k0 increased by increasing amount of fumaric acid in the initial mixture of the reaction. A mathematical model for the polyesterification based on the production parameters (e.g. the heating program) and on the kinetic parameters was used and very good correlation was found between the corresponding pair of curves of water produced during the polyesterification, which were determined experimentally and theoretically (by calculating). With regard to the properties of the final product it was found out that its viscosity and its slight yellow colour increased by increasing the amount of fumaric acid in the initial mixture of raw materials. General prospects for practical application of this method were also discussed.
Sphärische ionotrope gele carboxygruppenhaltiger cellulosederivate als trägermaterialien für biologische wirkstoffe, I. Struktur‐ und quellungsuntersuchungen an xerogelen aus carboxymethylcellulose und aluminiumionen
Authors: Heinze Thomas , Klemm Dieter , Winkelmann Heinz , Linß Werner
Published: April 2003

Unlösliche sphärische Aluminiumcarboxymethylcellulose‐Xerogelpartikel werden durch partielle Trocknung ionotroper Gele hergestellt, die durch Eintropfen wäßriger Lösungen von Natriumcarboxymethylcellulose in vernetzende Aluminiumsalzlösungen entstehen. Das Quellvermögen der porösen und mechanisch stabilen Trägermaterialien, die von einer dichten Außenschicht umgeben sind, erhöht sich durch partielle Umwandlung von Carboxygruppen in die Natriumsalze; es verringert sich mit zunehmendem Gehalt an freien Säuregruppen und steigender Trocknungstemperatur.
Studies on a macromolecular dichloroamine — the N,N‐dichloro poly(styrene‐co‐divinylbenzene) sulphonamide
Authors: Bogoczek Romuald , Kociołek‐Balawejder Elzbieta
Published: April 2003

Starting from a commercial sulphonate cation‐exchange resin via sulphonyl chloride and sulphonamide resins, a macromolecular dichloroamine with ca. 6 mmol of active chlorine per gram of resin was prepared. The conditions for its optimum preparation starting from poly(styrene‐co‐divinylbenzene)sulphonamide (poly(St‐Co‐DVB)SO2NH2) were stated. The possibility of iterated chlorination and dechlorination of the product was proved. Its stability in the range of 20–100°C, both in the dry state and in aqueous media, was determined. Moreover, its derivatographic examinations up to 1000°C were performed. Examples for the use of the macromolecular dichloroamine as a polymer supported reagent for chlorination, oxidation of several organic and inorganic species and water disinfection are given.
A study of CO2 and excimer laser treatments of poly(etheretherketone)
Authors: Occhiello E. , Garbassi F. , Malatesta V.
Published: April 2003

CO2 and excimer laser (193, 248, 350 nm) treatments were performed on poly(etheretherketone) (PEEK). High fluence excimer laser irradiation induced efficient etching, mainly due to thermal effects. The irradiation with CO2 lasers and high fluence excimer lasers introduced limited changes in surface chemistry and morphology.

Low fluence excimer laser irradiation, particularly at 193 nm and 248 nm, favored the occurence of photochemical phenomena. Surface chemical modifications leading to oxygen depletion and preferential elimination of the ketonic bridge were assessed. At the same time surface morphological alterations were found, diffraction effects led to cone‐like structures while the redeposition of heavy oligomers caused the formation of debris on the surface.
Electrochemical polymerization of pyrrole on a fabric
Authors: Chen Show‐An , Tsai Yuan‐Chien
Published: April 2003

An electrochemical method for polymerizing pyrrole on a glass fabric without using metal anode to give a polypyrrole/fabric composite is proposed. The glass fabric is precoated with a thin layer of polypyrrole polymerized by use of ferric chloride as oxidizing agent. Morphological change during the polymerization is also reported.
Effect of copolymers modifying PVC on its physical and mechanical properties and its UV‐radiation resistance, IX. Photodeformation of surface of pure PVC films and films containing MMA/MA and traces of cyclohexanone
Authors: Kamińska A. , Kamiński J. , Rozpłoch F. , Kaczmarek H.
Published: April 2003

By means of microscopic observation, the deformation of the surface of PVC films caused by 253.7 nm UV radiation was investigated. Numerous blisters and holes were formed by the gaseous photodecomposition products of the polymer.

More apparent deformation of the films containing MMA/MA suggests that the photodecomposition of this modifier occurs with higher efficiency than that of PVC.

MMA/MA copolymer is introduced into PVC films to improve the smoothness of their surface, but this modifier accelerates the deformation of this surface under UV irradiation. It was also found that traces of cyclohexanone in samples retard the photodecomposition of MMA/MA and accelerate this process in PVC.
Zur statistik des einbaus einer als regler in polyamid 12 verwendeten aliphatischen dicarbonsäure
Authors: Hartkopf Uwe , der Heyde Wolfgang Auf , Meyer Kurt
Published: April 2003

Als Hartblöcke in Polyetherblockamiden werden durch Dicarbonsäuren stark geregelte Polyamide eingesetzt. Da die Säure in Hinblick auf das Schmelz‐ und Kristallisationsverhalten einen Störbaustein in der Kette darstellt und bei einem ausgeregelten Produkt jede Kette ein Säuremolekül enthält, ist es von Bedeutung zu wissen, wo in der Kette der Einbau erfolgt. Anders als bei monofunktionellen Reglern, wo der Regler stets ein Kettenende bildet, kann ein bifunktioneller Regler a priori auch statistisch im Inneren der Kette eingebaut werden. Dies führt zu einer viel stärkeren Störung, als wenn das Reglermolekül und das sowieso als Störstelle wirkende Kettenende zusammenfallen. Anhand adipinsäuregeregelter Oligoamide auf Basis von Laurinlactam wird kernresonanzspektroskopisch der Einbau des Reglers untersucht und mit Rechnungen verglichen. Es ergibt sich nur dann gute Übereinstimmung, wenn vorausgesetzt wird, daß der Einbau statistisch erfolgt und dabei mit gleicher Wahrscheinlichkeit für jede beliebige Stelle zwischen zwei Laurinlactambausteinen oder am Kettenende abläuft. Weitere Rechnungen verdeutlichen den Einfluß des Reglereinbaus auf die Größe des amorphen Anteils.
An investigation of the controlled release of diacetylfluorescein (DAF) from polymeric membranes
Authors: Xu Ping , Wang Shuhong , Greenberg David B.
Published: April 2003

The release kinetics of diacetylfluorescein (DAF) from the polymeric membranes has been studied. The polymeric membranes were made of polystyrene and polysulfone materials in a monolithic form. This work employed a fluorescence spectrophotometer to monitor the release rates by the hydrolysis of DAF at 25°C. The investigation exhibited that the release rates follow a zero‐order kinetic scheme. The effects of different loadings of DAF and acetone on the controlled release rates were also exploited.
Concerning the degree of polymerization when using initiators with two peroxide groups
Authors: Wittmer Paul
Published: April 2003

In radical polymerizations with bifunctional initiators, an increase in the degree of polymerization in a batchwise reaction is only achieved at relatively high initiator conversions. This is, however, always achieved at the expense of a major decrease in the absolute value of the rate of polymerization.

In a polymerization in a continuous‐flow stirred tank reactor there are ranges in which the bifunctional initiator is superior. However, the polymers thus formed always have a polydispersity index different from the value obtained when using a monofunctional initiator.

The considerations presented here apply to polymerizations with combination termination, without chain transfer. In polymerizations with disproportionation termination and/or greater chain transfer the differences when using two types of initiator are substantially less and under certain circumstances disappear completely.
Thermooxidation yellowing of aliphatic polyamides
Authors: Fromageot Dominique , Roger Agnès , Lemaire Jaques
Published: April 2003

During the thermo‐oxidation at 90°C of unsubstituted or N‐substituted aliphatic polyamides, formation of products which absorb in the UV and visible regions is observed. These products are photo‐instable either at short wavelengths or at long wavelengths and their photo‐reactivity is wavelength dependent. These oxidized groups are identified as crotonized aldehydic groups (CH  CH)2 or 3 CHO similar to those formed in the photo‐oxidation at short wavelengths of aliphatic polyamides.
Untersuchungen des Reaktionsverlaufes und der Produkte der säurekatalysierten Reaktion von Phenolen mit Holzöl, 1. Phenol und Holzöl
Authors: Ziebarth G. , Singer K. , Gnauck R. , Raubach H.
Published: April 2003

Die zur Herstellung modifizierter Phenolharze für Elektroisolierschichtpreßstoffe wichtige säurekatalysierte Reaktion von Phenol mit Holzöl wird mittels Gas‐ und Flüssigchromatographie, IR‐, 1H‐NMR‐, 13C‐NMR‐Spektroskopie sowie MS untersucht. Es wird festgestellt, daß Phenol durch Holzöl im Sinne einer Friedel‐Crafts‐Reaktion C‐alkyliert wird; am Holzöl reagieren nur die Doppelbindungen der Eläostearinsäure.
Untersuchungen des Reaktionsverlaufes und der Produkte der säurekatalysierten Reaktion von Phenolen mit Holzöl, 2. Vergleichende untersuchungen an verschiedenen phenolen
Authors: Singer K. , Ziebarth G. , Schulz G. , Gnauck R. , Raubach H.
Published: April 2003

Die zur Herstellung holzölmodifizierter Phenolharze für Elektroisolierschichtpreßstoffe wichtige säurekatalysierte Reaktion von Phenolen mit Holzöl wird für 4 verschiedene Phenole (Phenol, o‐, m‐, p‐Cresol) vergleichend untersucht. Insbesondere durch 13C‐NMR‐ und IR‐Untersuchungen wird festgestellt, daß ausschließlich C‐Alkylierung des Phenols durch Holzöl im Sinne einer Friedel‐Crafts‐Reaktion abläuft. Die Reaktionsorte an den Phenolen werden ermittelt. Weiterhin werden die Geschwindigkeiten der Reaktion der Phenole mit den Eläostearinsäureresten verglichen.
Synthesis and impact behaviour of PMMA/EVA interpenetrated blends
Authors: Laurienzo Paola , Malinconico Mario , Ragosta Giuseppe , Volpe Maria Grazia
Published: April 2003

In the present work blends between poly(methylmethacrylate) (PMMA) and poly(ethylene‐co‐vinylacetate) (EVA) or its derivative EVA‐g‐succinic anhydride (EVA‐g‐SA) have been investigated by linear elastic fracture mechanics (LEFM) with Charpy impact tests and by scanning electron microscopy (SEM). Blends prepared by “insitu” radical polymerization of the acrylic monomer in the presence of the rubbers have an IPN morphology, while a blend prepared by melt‐mixing the polymer components shows the typical biphasic structure of rubbery domains dispersed in a glassy matrix.

Furthermore, a different behaviour is found when using EVA‐g‐SA instead of EVA. A fair agreement is found between the response of the LEFM analysis applied to the results of Charpy impact tests and the observed morphologies.
Unvernetzte Epoxid‐Amin‐Additionspolymere, 21. Dimethyl(aminomethyl)phosphinoxid, ein comonomeres für epoxidpolymere mit verminderter entflammbarkeit
Authors: Klee Joachim , Hörhold Hans‐Heinrich , Schütz Heidrun , Varbanov Sabi , Borissov Gueorgui
Published: April 2003

Es wird über die Herstellung von linearen, hochmolekularen Epoxid‐Amin‐Additionspolymeren und telechelen Prepolymeren berichtet, die mit Dimethyl(aminomethyl)phosphinoxid (DMAPO) ein flammwidriges Kettenglied in der Polymerkette enthalten. Die Struktur dieser Polymeren und Prepolymeren wird mittels Elementaranalyse, Mn‐Werten, IR‐, 1H‐NMR‐, 13C‐NMR‐ und 31P‐NMR‐Spektroskopie untersucht. Der Sauerstoffindex OI von DGEBA/DMAPO‐Polymeren erreicht etwa 30.

Auch der polare Charakter von Epoxid/Amin‐Additionspolymeren, der für die Haftung an metallischen und oxidischen Werkstoffen bedeutsam ist, wird durch den Einbau von PO(CH3)2‐Gruppen verstärkt. Ebenso wird hierdurch die photooxidative Stabilität verbessert.
Some kinetic features of the initial stage of acid catalyzed polycondensation of furfuryl‐alcohol and formaldehyde, III
Authors: Szesztay M. , László‐Hedvig Zs. , Tüdös F.
Published: April 2003

Accumulation of “dimers” and “trimers” considered to be inactive and consumption of active ones with reaction time in furfuryl‐alcohol (FA)/formaldehyde (F) acid catalyzed condensation system was proved by GPC technique using double detector.

A reaction mechanism was proposed for the condensation process explaining some contradictions of investigations collected so far.
Weak acid ion exchange membranes
Authors: Gasperowicz Aleksandra , Poźniak Gryzelda , Trochimczuk Witold
Published: April 2003

Weak acid ion exchange membranes were prepared by pressing methyl acrylate/methyl methacrylate and methyl acrylate/butyl methacrylate copolymers into the film form. Before shaping, the copolymers were hydrolysed in an alkaline solution (heterogeneous system). The following optimal hydrolysis parameters were established: temperature: 90°C; hydrolyzing agent potassium hydroxide/methylacrylate ratio: 5 mol/mol; concentrations: copolymer: 5 wt.‐%, emulsifier (Hostapal CV): 0.5 wt.‐%.

Products insoluble in water or alkaline solutions, yet containing enough carboxylic groups to provide an ion exchange selectivity, were obtained by hydrolysis of copolymers containing less than 30 wt.‐% of methyl acrylate units.

The ion exchange and transport properties (in the system 0.5 M NaOH//membrane//H2O) were found to be the best for the membranes obtained from hydrolysed poly(methyl acrylate‐co‐methyl methacrylate).
Polyamines containing β‐hydroxyurethane linkages as curing agents for epoxy resin
Authors: Rokicki Gabriel , Łaziński Robert
Published: April 2003

A method of obtaining modified amine curing agents containing β‐hydroxyurethane linkages is presented. The basic physical and chemical properties of the modified polyamines, such as viscosity and reactivity towards epoxy resins, have been studied.

A shortening of the gel and curing times in addition to a decrease of the exothermic effect accompanying the curing of an epoxy resin was found in comparison with the system containing an unmodified amine. Mechanical and thermomechanical studies showed a rise of the deflection temperature, hardness and strength features such as tensile strength, shear and peel strength for epoxy resins crosslinked with modified curing agents in comparison with those parameters obtained for resins crosslinked with the initial amines.
Functionalized polybutadiene oils as adhesion promotors for mineral fillers in rubber compounds
Authors: Haag Horst‐Günther , Herrmann Christoph , Kampf Wolfgang , Nordsiek Karl‐Heinz , Streck Roland , Zerpner Dieter
Published: April 2003

This paper deals with silylated and maleated polybutadiene oils and their effects in rubber compounds containing silica(tes) resp. chalk as fillers. They are shown to be efficient aids in the substitution of oil‐dependent carbon black by mineral fillers.
Study of thermal stimulated current and effect of annealing on cellulose nitrate
Authors: Mounir M. , Abd‐Eldaem A.
Published: April 2003

The investigated samples were cellulose nitrate CN‐85. The conductivity increases with temperature for unannealed samples and decreases with increasing time of annealing for annealed samples.

The activation energy is equal for all samples and amounts to 2.1 eV in a temperature range from 322 to 385 K. The behaviour is metallic (dσ/dT) < 0 for times of annealing larger than 24 h. The TSC current was measured. The position of the maximum slightly shifted towards higher temperatures with increasing rate of heating. The activation energy in the case of the TSC current was 0.21 eV and independent of the rate of heating. The dipolar relaxation time and imaginary dielectric constant were calculated theoretically and studied as a function of temperature.
Modification of transport properties of ion exchange membranes, X formation of polyethyleneimine layer on cation exchange membrane by acid‐amide bond
Authors: Sata Toshikatsu , Izuo Ryuji
Published: April 2003

In order to give the monovalent cation permselectivity to the cation exchange membrane permanently, polyethyleneimine layer was formed on the membrane surface by acid‐amide bond between polyethyleneimine and the SO2Cl groups of a styrene‐divinylbenzene copolymer membrane. After the reaction, the SO2Cl groups remaining in the inner part of the membrane were hydrolyzed by immersing the membrane into an aqueous sodium hydroxide solution.

The resultant cation exchange membranes were evaluated by electrodialysis of sea water from the point of view of the monovalent cation permselectivity, electric resistance of the membrane, current efficiency, and transport number of sodium ions calculated by membrane potential in connection with reduced viscosity of the various commercial polyethyleneimines, ATR‐IR measurements on the membrane surface suggested that the acid‐amide bond was stable for severe hydrolysis reaction.
Thermal and viscoelastic behavior of polyetheretherketone/polyethersulfone blends
Authors: Wu Zhongwen , Zheng Yubin , Yu Xiaomei , Nakamura Tomoki , Yosomiya Ryutoku
Published: April 2003

The polymer blends obtained by the solution blending method show a type of compatible polymer blends. The samples obtained by compression molding the polymer blends below the melting point of the polyetheretherketon (PEEK) exhibit dynamic viscoelastic behavior characteristic of compatible polymer blends, but those by compression molding above the melting point of the PEEK show a phase separation in dynamic viscoelastic behavior.
Epoxy groups on grafted polypropylene. I. Reaction with acids
Authors: Citovický P. , Chrástová V. , Beniska J. , Sedlář J. , Mejzlík J.
Published: April 2003

Epoxy groups on isotactic polypropylene, to which 2,3‐epoxypropylmethacrylate was grafted, were reacted with low molecular carboxylic acids. The reaction proceeds under heterogeneous conditions in the presence of organic solvents and it may be catalysed by tertiary amines. The rate constants of this reaction are correlated with the dissociation constant of the bonded acid and with the character of the used catalyst. The reactivity of polymer‐bonded epoxy groups is not changed when comparing with reactions performed under homogeneous conditions.
Epoxy groups on grafted polypropylene. II. Reaction with amines
Authors: Citovický P. , Malík J. , Beniska J. , Chrástová V. , Sedlář J.
Published: April 2003

Epoxy groups attached to isotactic polypropylene in form of 2,3‐epoxypropylmethacrylate grafts were reacted with low molecular secondary amines. Secondary heterocyclic amines exhibit high reaction rates in this process. The bonding of less basic amines is accelerated in the presence of acid catalysts. The mechanism is discussed of amine‐acid couple influence upon the epoxy group present in heterogeneous system on the surface of solid polymer.
A study of blends of poly(n‐octadecyl methacrylate) with n‐dodecane and n‐octadecane
Authors: Rubin Isaac D. , Pugliese Rocco D.
Published: April 2003

DSC and X‐ray diffraction analysis were used to study blends of poly(n‐octadecyl methacrylate) with n‐dodecane and n‐octadecane crystallized from the melt to gain a better understanding of the interaction of comb‐like polymethacrylates with paraffin waxes. In both sets of blends both components could crystallize in separate lattices. However, the polymer interfered with the crystallization of the n‐paraffin, resulting in less crystalline paraffin than expected on the basis of blend composition. In the blends with n‐dodecane, evidence was found for partial cocrystallization of the paraffin and the polymer side chains. No cocrystallization was observed in the blends with n‐octadecane.
Selective modifications of PMMA for effective decay of electrostatic charges
Authors: Dave A. M.
Published: April 2003

Poly(methyl methacrylate) (PMMA) modified with ion or metal containing monomers is found to exert no large improvement concerning electrostatic charging, but decreases discharge periods significantly depending upon the type and concentration of the modifying comonomer.

The newer approach reported here aims at making a representative thermoplastic like PMMA an antistatic polymer through selective copolymerization safeguarding the mechanical and optical properties as usual. Moreover, unlike the conventional approach of incorporating surfactants, the antistatic effects are exerted immediately after the polymer is made.
Hardening reactions of epoxy‐phenol systems in the presence of imidazole type catalyst by DSC
Authors: Lázló‐Hedvig Zs. , Molnár I. , Váradi J. , Tüdős F.
Published: April 2003

The thermal features of polyaddition and crosslinking of epoxy‐novolac resin mixtures and that of epoxy and phenol model systems—diane (DIANE) and dianediglycidyl ether (DDGE) — were studied in the temperature range of 20–250°C by DSC in the presence and absence of imidazole type catalysts (imidazole and benzimidazole). In the DDGE‐DIANE (mole ratio 2:1) system the exothermae showed a characteristic bimodality when catalyzed by imidazoles. The bimodal character could be interpreted in terms of the mechanism of action of the imidazoles.
Modellierung der umsatzabhängigkeit ausgewählter technischer kennwerte von PVC‐S unter nutzung von vorstellungen zur morphogenesis
Authors: Henschel Ines , Platzer Bernd
Published: April 2003

Gegenstand dieses Artikels ist die Berechnung einiger Eigenschaften von PVC‐Pulver, das nach dem Suspensionspolymerisationsverfahren hergestellt wurde. Ausgehend von einer Analyse der Einflußfaktoren und von experimentellen Daten wird ein Modell für die spezifische Oberfläche und für die Porosität des Pulvers entwickelt. Das Modell nutzt Gleichungen für die Morphogenesis von PVC‐S, die kürzlich in dieser Zeitschrift vorgestellt wurden, und frühere Arbeiten über den Kornbildungsprozeß. Damit berücksichtigt das Modell die Abhängigkeit der Produkteigenschaften von Reaktionskinetik, Umsatz, Temperatur, Vermischung und Dispergatorsystem. Es zeigt sich, daß die spezifische Oberfläche nur von der inneren Morphologie abhängig ist. Die Porosität ist darüber hinaus von einer eventuellen Mehrzelligkeit des Korns abhängig. Die Ergebnisse für die spezifische Oberfläche korrespondieren mit Daten, die nach der BET‐Methode bestimmt wurden; die Daten der Porosität (Quecksilber‐Hochdruck‐Porosimetrie) stimmen ebenfalls mit den durch das Modell berechneten überein. Die Eigenschaften von im Großreaktor hergestellten Produkten korrespondieren gut mit dem Modell.
Oberflächenstrukturierung polymerer fasern durch UV‐laserbestrahlung. 5. Oberflächenstrukturierung und laserablation von seide
Authors: Knittel Dierk , Schäfer Karola , Schollmeyer Eckhard
Published: April 2003

Durch Untersuchungen an Seide (Fibroin von Faltblattstruktur des β‐Keratintyps) wird untermauert, daß neben von außen aufgebrachten Spannungen und neben internen Spannungsfeldern in Synthesefasern auch Spannungen in einer Polymerkette, die durch ihren chemischen Aufbau bedingt sind, in Zusammenwirken mit einem laserinduzierten Temperaturfeld zur Strukturierung der Faseroberfläche führen können.

Die Bedeutung der erzielten regelmäßigen Rollenstruktur an Faseroberflächen für Anwendungsmöglichkeiten wird diskutiert.
Radiation induced grafting of methacrylic acid onto silk for the immobilization of antimicrobial drug for sustained delivery
Authors: Singh Harpal , Tyagi P. K.
Published: April 2003

Medical grade black braided silk suture and pure mulberry silk twisted yarn were grafted with methacrylic acid (MAA) using 60Co gamma radiation. The effect of various synthesis conditions on the grafting was studied. The addition of methanol in water has a marked effect on the degree of grafting, maximum yield of grafting was obtained in an equivolume mixture of water‐methanol. The percent grafting increased with the increase in the monomer concentration and in total radiation. For a constant total dose, grafting was found to be higher at lower dose rates. The order of the dependence of the rate of grafting on the dose rate was found to be 0.53 and 0.56 for medical grade black braided silk suture samples and mulberry silk twisted yarn samples respectively. The immobilization of an antimicrobial drug, 8‐hydroxy quinoline (8‐HQ) hydrochloride on the grafted pure silk for sustained delivery, its release in vitro and its antimicrobial activity were also studied. The percentage of 8‐HQ immobilized onto various grafted silk samples increased with the increase in the degree of grafting. The release of the drug in distilled water was sustained for 32 days. 8‐HQ was found to be active against both gram‐positive and Gram‐negative bacteria.
Glass fiber reinforced composites of epoxy resin cured with different amines
Authors: Thakkar Jatin R. , Patel Ravji D. , Patel Ranjan G. , Patel Vithal S.
Published: April 2003

Diglycidyl ether of bisphenol A (DGEBA), cured with six different curing agents, i.e. 4,4′‐diamino diphenyl sulfone (DDS), 4,4′‐diamino diphenyl methane (DDM), 4,4′‐diamino diphenyl ether (DDE), dicyandiamide (DICY), 4,4′‐diamino‐3,3′‐dichloro diphenyl methane (MOCA) and diethylene triamine (DETA), respectively, was studied for the kinetics of the thermal degradation. Such epoxy systems have been used to prepare the glass fiber reinforced laminates, which were evaluated for their properties such as heat distortion temperature (HDT) and resistance to chemical reagents. The mechanical properties like shore‐D hardness, flexural strength and interlaminar shear strength (ILSS) as well as dielectric properties like dielectric constant, tan δ, electrical resistance and breakdown voltage have also been estimated. The composition prepared using an epoxy fortifier showed improvement in flexural strength and interlaminar strength up to ≈33% and ≈36%, respectively.
Mischungen aus semiflexiblen, flüssigkristallinen polyestern und polystyrol
Authors: Braun Dietrich , Schülke Ulrike
Published: April 2003

Mischungen aus Polystyrol und einem semiflexiblen, flüssigkristallinen Polyester werden durch gemeinsames Ausfällen von Polymerlösungen hergestellt und differentialkalorimetrisch und polarisationsmikroskopisch untersucht.

Des weiteren werden Mischungen der gleichen Komponenten durch radikalische in situ Polymerisation von Styrol in Anwesenheit des Polyesters hergestellt; das thermotrope Verhalten des flüssigkristallinen Polyesters in diesen Mischungen wird mit den oben genannten verglichen.

Die Untersuchungen ergeben, daß nach der zweiten Methode Polystyrolpfropfäste am Polyester entstanden sind, was auch durch Extraktion des Homopolystyrols und nachfolgende IR‐spektroskopische Untersuchung des Rückstandes bewiesen wird. Aufgrund dieser Verträglichkeitsvermittler ist der Polyester feiner in der Polystyrolmatrix verteilt, und die Kristallisation tritt bei tieferen Temperaturen ein als beim reinen Polyester.

Um die Bedingungen der Pfropfreaktion zu verbessern, wurden mit Styrol copolymerisationsfähige Doppelbindungen über 4,4′‐Fumaroyldioxydibenzoylchlorid in den Polyester eingebaut. Die anschließende Pfropfcopolymerisation mit Styrol führte aber nicht zu Produkten mit wesentlich veränderten Eigenschaften gegenüber der Pfropfung mit dem gesättigten Polyester.
Incorporation of a well‐defined polyether side‐chain into segmented poly(ether‐urethane urea) and examination for blood‐compatibility
Authors: Hashimoto Hisaho , Demachi Ayako , Nishimata Toyoki , Sasamura Yasuaki , Iida Kazutoshi , Kaneko Noriaki , Sakamoto Nagayoshi , Kakuchi Toyoji , Yokota Kazuaki
Published: April 2003

A new method of introducing a hydrophilic polyether side chain into segmented polyurethane using a polypropylene oxide macromer with 1,3‐diol at one chain‐end, which behaves as chain extender, is described. In this procedure, a molecular‐designed side‐chain is incorporated quantitatively and directly into polyurethane biomedical elastomer. The design is also of interest to biomaterials in artificial organs.
Curing of epoxides. Reaction of dicyanodiamide with phenylglycidyl ether
Authors: Zeppenfeld Gisela , Matějka Libor , Špaček Pavel , Schmidt Pavel , Dušek Karel
Published: April 2003

Curing of epoxy resins with the latent hardener 1‐cyanoguanidine (dicyanodiamide) was studied using a model system. Phenylglycidyl ether was reacted with 1‐cyanoguanidine in the presence of benzyldimethylamine as a catalyst in a solution in 2‐methoxyethanol. The reaction kinetics was followed by means of HPLC and IR spectroscopy. Some of the reaction products were isolated by semipreparative HPLC and identified.

The influence of temperature and of the initial ratio of reaction components on the reaction mechanism was studied. Three partial reactions were found: a) addition of the amino groups of 1‐cyanoguanidine to the epoxide, which then initiates the reaction of OH groups of the addition products, b) with the C≡N group, or c) with the epoxide (etherification). The relative extents of the latter two reactions increase with conversion. The reaction of the nitrile group is preferred at high temperatures but depressed in the presence of excess epoxide in the reaction mixture when etherification prevails.
Bigraft copolymer EVA‐g‐AA‐g‐HEMA from peracid type polymeric initiator
Authors: Hsiue Ging‐Ho , Chu Hsiao‐Lung
Published: April 2003

In this study a poly(ethylene‐co‐vinylacetate) grafted with acrylic acid (EVA‐g‐AA) film was used as a substrate, whose carboxyl groups can be oxidized to form a highly reactive polymer initiator. The activation energy for its decomposition is 13.41 kcal/mol. The peracid type membrane has a high reactivity and 2‐hydroxyethyl methacrylate (HEMA) can be easily grafted on to form a bigraft copolymer EVA‐g‐AA‐g‐HEMA. The properties and morphology of the bigraft copolymer were discussed.
Etude de polymères thermostables en vue de leurs applications en electronique
Authors: Boiteux G. , Oraison J. M. , Seytre G. , Vallet G. , Davenas J. , Mariaggi P. , Senneron M. , Sillion B.
Published: April 2003

Heat resistant polymer are more and more needed for structural applications in aerospace and for electrical applications in electronics.

Thermostable dielectric coatings are used as intermetallic layers in wafer fabrication or for interconnection processes and dielectric films find their main applications for the production of flexible circuits. On the other hand, for the development of surface mount technology, heat resistant films are required, due to the severe thermal stresses encountered by the components during the wave soldering.

Among the heat resistant polymers, polyimides are the most popular. In spite of all the works performed on polyimides, these materials still exhibit certain shortcomings such as good processability. An approach to improve the processability involves the synthesis of fully cyclized linear polymers with a good solubility. For this we can introduce in the main chain flexible linkages (ether, carbonyl, sulfone), lateral groups with large steric hindrance or polar groups giving strong interactions with solvent.

We will discuss in this paper the synthesis and the thermal and dielectric properties of various heterocyclic polymers fully cyclized and soluble.

Additionally, new applications of polyimides can be relevant regarding the properties which are obtained under irradiation with ion‐beams. We will present some results on the effect of irradiation and the induced conductive character of such materials.