bluuebunny/crossref_metadata_2025 huggingface dataset:
Herstellung von Copolymeren mit definierter Zusammensetzungsverteilung im Zulaufverfahren
Authors: Probst Joachim , Kolb Günter
Published: April 2003

In der vorliegenden Arbeit wird die Möglichkeit der Berechnung von binären und ternären Copolymerisationen im Zulaufverfahren demonstriert. Hierzu muß der Umsatz als Funktion der Zeit und der Dauer des Zulaufs bekannt sein. Die rechnerischen Simulationen werden auf das binäre System Methacrylsäure‐(N‐dimethylaminoethyl)‐ester/Styrol und die ternären Systeme Methacrylsäure‐(N‐dimethylaminoethyl)ester/Styrol/Acrylnitril sowie Methacrylsäure‐(2‐hydroxyethyl)‐ester/Styrol/Acrylsäuire‐n‐butylester mit gutem Erfolg angewendet. Mittels dieser Rechnersimulationen ist die Bestimmung der chemischen Umsatzheterogenität möglich. Weiterhin erlauben diese Berechnungen, Dosierprogramme für das Zulaufverfahren zu finden, bei denen Copolymere mit definierter Vereilung der chemischen Zusammensetzung entstehen. So ist es z. B. möglich, das normalerweise sehr heterogene Terpolymersystem Methacrylsäure‐(2‐hydroxyethyl)‐ester/Styrol/Acrylsäure‐n‐butylester durch entsprechende Dosierschemata in der chemischen Zusammensetzung wesentilich homogener aufzubauen. Beim ternären System Methacrylsäure‐(N‐dimethylaminoethyl)ester/Styrol/Acrylnitril, bei dem möglicherweise ein innerer ternärer Azetoropbereich existiert, wird gezeigt, bei welchen anfänglichen Monomermischungen chemisch homogene Terpolymere entstehen.
Neue Kautschuk‐modifizierte Thermoplaste
Authors: Neuray Dieter , Ott Karl‐Heinz
Published: April 2003

Das Prinzip der Kautschuk‐Modifizierung von Thermoplasten wird kurz erläutert. Berichtet wird über die Elastifizierung von Polybutylenterephthalat, Polyamiden und Polycarbonaten mit Butadienpfropfpolymerisaten. Die Kerbschlagzähigkeit, insbesondere bei tiefen Temperaturen (−40°C), wird erheblich verbessert, ohne andere relevante Eigenschaften wie die Wärmeformbeständigkeit wesentlich zu beeinflussen.
Amorphe Polyamide auf Basis Isophthalsäure und Hexamethylendiamin
Authors: Nielinger Werner , Brassat Bert , Neuray Dieter
Published: April 2003

Im vorliegenden Artikel werden Eigenschaften und Anwendungsmöglichkeiten des Polyamids aus Isophthalsäure und Hexamethylendiamin beschrieben. Dieses Produkt zeichnet sich durch hohe Transparenz und weitgehende Unabhängigkeit der mechanischen und elektrischen Eigenschaften vom Konditionierungszustand aus. Andere typische Polyamideigenschaften wie Festigkeit, Zähigkeit, Chemikalienbeständigkeit und Kriechstromfestigkeit sind erhalten geblieben.
Chemische und physikalische Vorgänge bei der Herstellung von Polyurethan‐Weichschaumstoffen
Authors: Hauptmann Günter , Dörner Karl‐Heinz , Hocker Jürgen , Illger Hans Walter , Pfisterer Gerhard
Published: April 2003

Die Kinetik der Schaumbildung wird IR‐spektroskopisch verfolgt. Polyurethanund Polyharnstoff‐Bildung laufen nebeneinander ab, wobei der Übergang von gelöstem zu kristallinem Harnstoff chronologisch erfaßbar ist. Der Unterschied zwischen Heiß‐ und Kalt‐(HR)‐Schaum wird deutlich. NCO‐ Vernetzungsreaktionen lessen sich durch IR‐Spektren nicht nachweisen. An einem Schaum der Rohdichte 26 kg/m3 wird eine quantitative Bilanz der Schaumbildung mit chemischen Analysenmethoden aufgestellt. Gasausbeute und Geschwindigkeit der Aushärtung werden bestimmt.
Ermittlung der Sequenzverteilung und Taktizität bei Acrylnitrill/Vinylidenchlorid‐Copolymeren
Authors: König Joachim , Wendisch Detlef
Published: April 2003

Ein Acrylnitril/Vinylidenchlorid‐Copolymerisat, hergestellt durch kontinuierliche Fällungspolymerisation in wäßrigem Medium, wurde durch 13C‐Kernresonanz bei 90,52 MHz untersucht. Die Sequenzverteilung konnte übereinstimmend abgeleitet werden aus der Diaden‐ bzw. Tetradenverteilung des Methylenbereiches und aus den Triadenverteilungen der übrigen Kohlenstoffatome. Aus den Signalen von Methinund Nitrilkohlenstoff ließ sich die stereochemische Ordnung der Acrylnitril‐Einheiten ableiten, die in Übereinstimmung mit radikalisch hergestelltem Acrylnitril‐Homopolymerisat eine geringe Bevorzugung der isotaktischen Tßade gegenüber der syndiotaktischen Triade aufwies.
Synthesis of cyclolinear phosphazene oligomers by reaction of cyclophosphazene dichloride trimer, disodium salts of dihydroxy compounds and sodium‐p‐bromophenolate
Authors: Łaszkiewicz Bogumił , Kotek Ryszard
Published: April 2003

Chlorine substitution reactions of phosphonitrilic chloride with discodium salts of bis‐(2‐hydroxyethyl)‐terephthalate or bisphenols and sodium p‐bromophenolate were carried out in tetrahydrofuran to produce cyclolinear oligomers. The determined molecular weight of these compounds was about 2300 to 3100. The infrared spectra of the oligomers were measured and their thermal properties were described. The oligomer synthesized from bis‐(2‐hydroxyethyl)‐terephthalate and p‐bromophenol when incorporated into polyester fibres provides them with flame retardancy.
Reactive polymers, XXXIX. Synthesis of copolymers of glycidyl methacrylate‐ethylene dimethacrylate with aminopyridines and their sorption properties
Authors: Švec F. , Jehličková A.
Published: April 2003

The preparation of sorbents by reacting the copolymer glycidyl methacrylate‐ethylene dimethacrylate with aminopyridines is described. The sorption properties of ion exchangers thus obtained were determined. The ions used in the sorption were Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II). The way of binding the ion on the polymer was assessed. It was found that the polymers were weakly basic anion exchangers, probably able to form complexes under certain conditions.
Vernetzung von Filmen aus Emulsionspolymerisaten
Authors: Penzel Erich , Zosel Albrecht
Published: April 2003

Nach der Theorie der Kautschukelastizität kann man ein Netzwerk durch die Konzentration der Netzbögen v im Einheitsvolumen charakterisieren.

Man erhält vE durch einfache Rechnung aus Messungen des Elastizitätsmoduls, oder bei Kenntnis des Flory‐Huggins‐Parameters χ aus Quellungsmessungen vQ. Bei Mengen bis zu 4 Gew.‐% N‐Methylomethacrylamid (MAMol) ist die Übereinstimmung zwischen beiden Methoden und mit dem aus der Vernetzerkonzentration folgenden vth gut. Bei Höheren MAMol‐Mengen steigen sowohl die vE‐Werte als auch die vQ‐Werte über die theoretischen Höchstwerte vth an.

Es wird gezeigt, daß die Theorie der Kautschukelastizität das elastische Verhalten von Emulsionspolymerisaten aus Ethylacrylat bei niedrigen Vernetzerkonzentrationen qualitativ beschreibt.
Photoabbau von PVC‐Folien. IV. Einfluß des Sauerstoffs
Authors: Braun Dietrich , Bezdadea Eugen
Published: April 2003

Es wurden Masse‐PVC‐Folien verschiedener Dicke sowohl unter Stickstoff und Sauerstoff als auch unter mehreren Gemischen dieser beiden Gase mit einer Quecksilberhochdruckdampflampe bestrahlt. Verschiedene Aspekte des eingetretenen Photoabbaus wurden untersucht, darunter die HCI‐Abspaltung, die Zunahme der Carbonylkonzentration in den bestrahlten Folien mit der Sauerstoffkonzentration im Trägergas und die Abhängigkeit der Strukturänderungen des Polymeren von der Temperatur der Probe.

Es wurde gefunden, daß zwischen den beobachteten chemischen Veränderungen der bestrahlten Folien und der Sauerstoffkonzentration im angewendeten Gasgemisch eine direkte Beziehung besteht.
Investigation of the effect of gamma rays on the properties of polyamide fibres, I. The changes of some mechanical and chemical properties
Authors: Szymański W. , Lerke G. , Rymian B.
Published: April 2003

Measurements of mechanical resistance and of some chemical changes were performed for a γ‐irradiated PA 6 polyamide fibre in the form of surgical threads. A relatively high radiation durability was established for irradiation doses of the order of 104 Gy. The sterilizing dose was assumed to be 3 ·104 Gy. It was argued that in this dose range a deterioration of the mechanical properties of about 5% should be expected.
Isocyanate modified polyimides
Authors: Ghatge N. D. , Dandge D. K.
Published: April 2003

The synthesis of four different polyimides modified by 3,3′‐sulfonyl‐bis(phenyl isocyanate) was achieved and the electrical properties of polymer films were measured.
Konversion von epoxidharzen im kritischen zustand
Authors: Liška Vladimír , Adámková Gabriela
Published: April 2003

Kritische Größen der mit üblichen Härtemitteln vom Polyamin‐ und Anhydridtyp auszuhärtenden Epoxidharze wurden chemorheologisch bestimmt. Die im kritischen Zustand chemisch bestimmte Konversion von Epoxidgruppen wurde mit dem Charakter des Härtemittels und mit der Reaktivität von Epoxidharz/Härter‐Mischung korreliert.
The analysis of 13C NMR spectra of mixtures containing isotactic and atactic polystyrene
Authors: Standt Ulrich‐D. , Klein Joachim
Published: April 2003

A method to calculate the portion of isotactic polystyrene from the 13C‐NMR spectra of mixtures containing atactic and isotactic polystyrene is proposed and applied to an extract from an isotactic raw polymer. The result is in acceptable agreement with DSC measurements.
Autohäsion von Elastomeren
Authors: Bothe Lothar , Rehage Günther
Published: April 2003

Bringt man zwei Proben des gleichen Elastomeren in Kontakt, so tritt eine Haftung auf, die man Autohäsion nennt.

Die Haftfestigkeitszunahme mit der Kontaktzeit wird durch eine grenzflächenüberschreitende Diffusion von beweglichen Makromolekülkettenenden hervorgerufen. Bei der Autohäsion von unvernetzten Elastomeren läuft dieser Vorgang so lange ab, bis die Volumenfestigkeit des Elastomeren in der Kontaktzone erreicht wird.

In dieser Arbeit wurde die Autohäsion von Polybutadien, Acrylnitril‐Butadien‐Copolymeren, Ethylen‐Propylen‐Copolymeren und Polychlorbutadien untersucht. Im einzelnen wurden die Einflüsse des Molekülbaus, polarer Seitengruppen, der Kristallinität, der Kontaktzeit, der Zerreißgeschwindigkeit sowie der Einfluß von Lösungsmitteln auf die Haftungseigenschaften der Elastomeren behandelt.
A new method of characterizing molecular networks with the van der waals equation of state
Authors: Eisele U. , Heise B. , Kilian H.‐G. , Pietralla M.
Published: April 2003

The utility of the van der Waals equation of state for real networks is demonstrated by its application to various rubbers. A new method of characterization of networks as well as a discussion of its consequences are presented.
The heterogeneous structure of polyurethane networks
Authors: Lipatova T. E. , Shilov V. V. , Minenko N. N.
Published: April 2003

Using small‐angle X‐ray scattering the microheterogeneous structure of amorphous polyurethane networks was investigated. It was found to be determined by the corresponding structural characteristics of the initial oligomeric diols. The structure of the oligomers is preserved more or less depending on their chain length in polymeric networks (poly(oxypropyleneglycol) with molecular weights of 2000 and 500 g/mol, resp.). In the latter case a great influence on the structure is exerted by rigid fragments around crosslinks which are characterized by great concentrations of H‐bonds. This is leading to a decrease in the heterogeneity. The heterogeneous structure of the polyurethane networks becomes more distinct with an increase in the oligomer chain length and degree of conversion. The observed effects are explained by the change in the degree of aggregation of parts of the network structure.
Structural changes of acrylic solutions during non‐Newtonian flow
Authors: Stoyanov A. I.
Published: April 2003

By means of the Eyring‐Frenkel equation \documentclass{article}\pagestyle{empty}\begin{document}$\eta = {\rm A}_{0} e^{\Delta {\rm G}_{{\rm VISC}} /{\rm RT}}$\end{document} and the assumption that A0 = 10−3 poise the influence of shear rate, molecular weight and concentration on some structural changes of acrylic solutions during non‐Newtonian flow was investigated. It was established that the shear rate and the concentration influenced the activation heat and the activation entropy of viscous flow. The structural changes of acrylic solutions depending on molecular weight possessed an entropy character.
Photochemical grafting of acrylated azo dyes onto polymeric surfaces, IV. Grafting of 4‐(N‐ethyl‐N‐2‐acryloxyethyl)amino‐4′‐nitro‐azobenzene onto cellulose
Authors: Bellobono Ignazio Renato , Calgari Seba , Leonardi Maria Cristina , Selli Elena , Paglia Ernestina Dubini
Published: April 2003

Photochemically induced grafting and graft‐polymerization of 4‐(N‐ethyl‐N‐2‐acryloxyethyl)amino‐4′‐nitro‐azobenzene I, brought into contact in the solid state with cellulose by evaporation of solvent from monomer solutions, has been investigated kinetically at 30°C. Two constant rate periods were observed. The first one was interpreted on the basis of a self‐sensitized grafting mechanism of monomeric or oligomeric species of I, photochemically initiated by hydrogen abstraction from the cellulose surface. The second one was explained as a self‐sensitized photochemically induced graft‐polymerization of I on the first grafted layer. Some particular features, such as concurrent photodegradation of the first grafted layer at low surface coverage, are discussed in the light of the proposed mechanism.
Bifunctional initiators, II. Synthesis and characterization of 5,5′‐azo‐bis‐(5‐cyanocaproyl)‐benzoyl diperoxide
Authors: Shaikh Abdul Sattar , Comǎniţǎ Eugenia , Dumitriu Severian , Simionescu Cristofor
Published: April 2003

5,5′‐Azo‐bis‐(5‐cyanocaproyl)‐benzoyl diperoxide was synthesized starting from 5,5′‐azo‐bis‐(5‐cyanohexanoic) acid, obtained in its turn from 5‐keto‐hexanoic acid, hydrazine sulphate and sodium cyanide.

5,5′‐Azo‐bis‐(5‐cyanohexanoic) acid was then converted into acid chloride and condensed with perbenzoic acid. The structures of intermediates and of the product were elucidated by means of elemental analysis and IR and NMR spectral measurements.

In order to settle the bifunctional character of the synthesized initiator the thermolysis rate constants for azo and peroxy groups, energies of activation and half‐life times were settled. By comparing the kinetic data with those obtained in 4,4′‐azo‐bis‐(4‐cyanovaleryl)‐benzoyl diperoxide thermolysis the decomposition rate was found to increase and the bifunctional character to enhance with increasing length of the radical connecting the azo and peroxy groups.
Effect of mercerization‐stretching on vinyl graft polymerization of cotton
Authors: Hebeish A. , El‐Rafie M. H. , Khalil M. I.
Published: April 2003

Scoured ply cotton yarn was slack mercerized and slack mercerized followed by restretching the yarn in the mercerizing solution to 90, 94, 96, 100, and 103% of the original length. The six substrates so obtained together with scoured cotton were grafted independently with methyl methacrylate and acrylonitrile using ceric ammonium nitrate as initiator. The extent and rate of grafting found with slack mercerized cotton were significantly higher than those of scoured cotton irrespective of monomer used.

The same holds, but lo lesser degree, good for slack mercerized cotton followed by restretching to 90% of original length. Different situation was encountered with slack mercerized cotton followed by restretching to 94 and 103%; these substrates showed lower extent and rate of grafting than scoured cotton. Moreover, the extent and rate of grafting decreased by increasing the magnitude of stretching. Similar trend was observed when all the said substrates were subjected to oxidation with ceric ions. It is believed that there must be differences in microstructural features between scoured cotton, slack mercerized cotton and slack mercerized‐restretched cottons that account for this.
Studies on syntheses and permeabilities of special polymer membranes, 32. New preparation method of cellulose membranes
Authors: Uragami Tadashi , Sugitani Yasuhiro , Sugihara Mizuho
Published: April 2003

The preparation of cellulose membranes from mixtures of cellulose, nonprotonic polar organic solvents, paraformaldehyde, and basic catalyst was studied. When dimethyl sulfoxide was used as casting solvent, the resulting membrane was the densest. An increase of an additional amount of triethyl amine used as basic catalyst gave denser membranes.
Studies on polymers prepared from thiophenol: An electroanalytical approach. I. Studies on poly(phenylene sulphides)
Authors: Viswanathan P. S. , Vasudevan P.
Published: April 2003

In this paper we report some of the physico‐chemical changes occurring in poly(phenylene sulphide) prepared by the homopolycondensation of thiophenol. The various electrical properties measured on these polymers were used to identify the temperatures at which these transitions occur.
Polymerization of lactams, XLI. Molecular characterization of linear and branched polycaprylolactam
Authors: Prokopová Irena , Tuzar Zdeněk , Kondelíková Jaroslava , Schmiedová Daniela , Králíček Jaroslav
Published: April 2003

Samples of linear polycaprylolactam have been prepared and fractionated, and the [η]‐Mw relationship has been established in m‐cresol. Statistically branched samples have been obtained by copolymerizing 8‐caprylolactam with bislactams. The degree of branching as well as the branching ability of different bislactams are discussed and compared with the corresponding data for branched polycaprolactams.
Grafting onto wool, XVII. Graft copolymerization of methyl acrylate and ethyl acrylate by use of VO(acac)2 as initiator. Comparison of monomer reactivities
Authors: Misra B. N. , Sood D. S. , Sharma R. K.
Published: April 2003

Graft copolymerization of acceptor monomers methyl acrylate and ethyl acrylate onto Himachali wool fiber has been studied in aqueous medium by using vanadium oxyacetyl acetonate as initiator at 40, 50, 60, and 70°C. Graft copolymerization was carried out for various reaction periods and nitric acid was found to catalyse the reaction. Percentage of grafting and percent efficiency have been determined as functions of concentration of nitric acid, concentration of initiator, concentration of monomer, time, and temperature. Under optimum conditions, methyl acrylate and ethyl acrylate afforded maximum grafting to the extent of 28.4 and 18.5%, respectively. Relative reactivities of methyl acrylate and ethyl acrylate towards grafting have been compared with those of methyl methacrylate, acrylic acid and vinyl acetate reported earlier from this laboratory. Different vinyl monomers showed the following reactivity order: MMA > MA > EA > AAc > VAc. Several grafting experiments were carried out in the presence of various additives which included tert‐butylhydroperoxide (TBHP), dimethylsulfoxide, pyridine, and dimethylformamide. Only TBHP was found to enhance grafting to a considerable extent, other additives decrease percent grafting of both methyl acrylate and ethyl acrylate.
A contribution to the investigation of PVC‐plasticizer interactions
Authors: Drexler Jiří , Šimoník Josef
Published: April 2003

Temperature dependent characteristics of blends of suspension poly(vinyl chloride) with low and high molecular weight plasticizers in the region of processing temperatures have been investigated. The interaction process has been studied under dynamic conditions using the differential thermal analysis (DTA) method under non‐iso‐thermal conditions. As a result of the DTA curves evaluation as well as of the discussion of results it has been shown that the energy transformation occurring during the PVC‐plasticizer system processing is manifested by changes of thermal behavior. The values of heat released, corresponding to the maximum heat transfer rate have been identified as primary data which can be used in correlations describing the quality of plasticizers present in the system. The correlational relations covering the region of processing temperatures provide a “homogeneity” criterion of the system, corresponding to the plasticizing capability of the plasticizer involved.
Study of the reaction between urea and formaldehyde by dsc and 13C NMR spectroscopy
Authors: Šebenik A. , Osredkar U. , Žigon M. , Vizovišek I.
Published: April 2003

The reactions of urea with formaldehyde were studied by means of 13C NMR spectroscopy and differential scanning calorimetry (DSC) in acid and neutral medium, the temperature range being between 290 and 390 K. At higher pH the peak of the DSC curve splits into two peaks one of which belongs to the addition of formaldehyde to urea and the second to the subsequent condensation of the latter. For both reactions, the activation energy, heat of polymerization, reaction order and temperature maximum have been determined. The usefulness of DSC to study the kinetics of more complex polycondensation reactions was established.
Structure and properties of poly(ethylene terephthalate) crystallized by annealing in the highly oriented state. 3. Dynamic‐ and static‐mechanical properties
Authors: Fakirov Stoyko , Stahl Dieter
Published: April 2003

Commercial undrawn and cold drawn (5 × ) poly(ethylene terephthalate) (PETP) fibers and bristles have been annealed with fixed ends for 6 h in vacuum at different temperatures between 60 and 260°C. With these samples static‐ and dynamicmechanical measurements have been carried out.

It has been found that the α‐and β‐processes as well as the moduli depend on the annealing temperature (Ta) in different way, for undrawn and drawn material. The temperature position of the β‐peak evaluated from tg δ and loss modulus as well as the step height of α‐ and β‐processes are unsensitive to the Ta for the undrawn material in contrast to the drawn one for which maxima are observed. The appearance of these maxima is explained by the dominating role at the corresponding crystallization temperature of one of the two concurrent processes ‐ crystallization and disorientation, reflected in the change of the effective density of amorphous regions.

The dynamic and static measured moduli as well as the stress at break for drawn PETP decrease with the increase of annealing temperature as generally observed. The predominating significance of orientation and the state of amorphous phase in comparison with crystallinity is demonstrated.

An extremely high deformation ability at room temperature (up to 200%) of previously drawn and annealed at 255 or 260°C bristles is observed. This originates from the solid state postcondensation and premelting phenomena taking place during annealing in vacuum.
Methoden zur Verfolgung der Herstellung von Melamin‐Formaldehyd‐Harzen
Authors: Braun Dietrich , Günther Peter , Pandjojo Wirjopartono
Published: April 2003

Bei der Kondensation von Melamin (M) mit Formaldehyd (F) wurde zur schnellen Reaktionskontrolle die Bestimmung der Wasser‐ und Acetonverträglichkeit herangezogen. Die Einflüsse von pH‐Wert und MF‐Molverhältnis auf diese Messungen wurden untersucht. Sowohl mit den mit Wasser ausgefällten als auch mit den in Lösung verbliebenen Harzfraktionen wurden gelchromatographische Untersuchungen durchgeführt.

Die Bestimmungen von Wasser‐ und Acetonverträglichkeit sind wegen der starken Abhängigkeit der Meßergebnisse von den Reaktionsbedingungen nur bedingt zur Beschreibung von Harzzusammensetzungen geeignet.
Enzymatic hydrolysis of cotton wastes. Effect of γ‐ray pretreatments
Authors: Focher Bonaventura , Marzetti Annamaria , Santoro Cataldo , Sarto Virginio , D'Angiuro Luigi
Published: April 2003

Textile cotton wastes were irradiated with γ‐rays at different doses and solubilized with 10% NaOH solutions. The regenerated products underwent enzymatic hydrolysis and their degradation pattern was compared with that of the cotton celluloses untreated or treated only with γ‐rays. The different samples were characterized by measurements of X‐ray diffraction, degree of polymerization, moisture regain and water retention. The structural and morphological modifications induced by the pretreatments were correlated with the variations of kinetic parameters, particularly the Vmax/Km ratio, defined as specificity constant. Only the combination of irradiation with dissolution pretreatments gave a considerable increase of hydrolysis reaction effectiveness.
Untersuchungen der Molgewichtsverteilung von Harnstoff‐Formaldehyd‐Leimharzen
Authors: Dunky Manfred , Lederer Klaus
Published: April 2003

Handelsübliche, als wäßrige Dispersionen angelieferte UF‐Leime wurden gefriergetrocknet und das Leimharz in DMSO gelöst mit GPC (Gele auf Basis von Vinylacetat‐Divinyladipat, Säulenlänge 2‐10 m), Dampfdruckosmometrie und Lichtstreuung untersucht. Dabei wurde festgestellt, daß höherkondensierte UF‐Harze Anteile mit sehr hohem Molekulargewicht (M > 100 000 g/mol) enthalten. Es wurde nachgewiesen, daß sich diese Anteile in der dispersen Phase des Leimes anreichern und in DMF weitgehend unlöslich sind. Die Leistungsfähigkeit der entwickelten Methodik zur GPC von UF‐Leimharzen wird schließlich anhand von Untersuchungen der Alterung in wäßriger Dispersion (20°C) und in DMSO (60°C) demonstriert.
Copolyimides new polybenzoxazinone‐imides
Authors: Neamţu Gabriela , Brumǎ Maria
Published: April 2003

New polybenzoxazinone‐imides have been synthesized by cyclopolycondensation reaction of 4,4′‐diaminodiphenylmethane‐3,3′‐dicarboxylic acid with diacid chlorides containing preformed imide rings. The low temperature solution polycondensation technique, used in these experiments, afforded poly(amic acids) of high molecular weight in the first step, which subsequently underwent thermal cyclodehydration at 200–300°C to give polybenzoxazinone‐imides in the second step. The obtained polymers have been characterized by IR absorption, elemental and thermogravimetric analyses. From 10% polymer solution flexible and transparent films have been cast with good mechanical and insulating properties.
High‐temperature polymers polybenzothiazole‐amide‐imides
Authors: Neamţu Gabriela , Mandric G. , Zugrǎvescu I.
Published: April 2003

A series of new polymers containing benzothiazole, imide and amide units in macromolecular chains were prepared. The polymers were synthesized by low temperature polycondensation of aromatic diamines containing benzothiazole rings with diacid chlorides containing preformed imide rings. The obtained polymers are soluble in aprotic dipolar solvents and they have high molecular weights (ηinh = 0.4−1.2 dl/g), high thermal stability up to 400°C and good chemical resistance. From 10% polymer solutions flexible and transparent films have been cast with good physicomechanical properties.
Preparation of silica by acid dissolution of sepiolite and study of its reinforcing effect in elastomers
Authors: Hernández L. González , Rueda L. Ibarra , Diaz A. Rodriguez , Antón C. Chamorro
Published: April 2003

The preparation of amorphous silica by acid treatment of a natural magnesium silicate and its use as reinforcing filler for NR and SBR compounds are studied. Limited to the treatment with nitric acid, the rate constants at different temperatures and acid concentrations and the activation energy are calculated, as a function of percentage of extracted magnesium.

The resulting material is basically an amorphous silica (92.5% SiO2), as shown by X‐ray analysis, that keeps the fibrous morphology of the original mineral. According to a preliminary technological study the resulting silica is a suitable reinforcing filler for general purpose rubbers; a comparison between the experimental results and those obtained with a commercial fine particle precipitated silica was made. Using a SBR compound the effect of silane coupling agents on the new silica was studied.
Polymerization of glycidyl methacrylate, methacrylic acid, acrylamide and their mixtures with cotton fabric using fe2+‐thioureadioxide‐H2O2 redox system
Authors: Waly A. , Abou‐Zeid N. Y. , El‐Alfy E. A. , Hebeish A.
Published: April 2003

Polymerization of glycidyl methacrylate (GMA), methacrylic acid (MAA), acrylamide (Aam) and their binary mixtures with cotton cellulose fabrics using Fe2+‐thioureadioxide‐H2O2 redox system was investigated under a variety of conditions. While temperatures of 50, 80, 65, and 95°C constituted the optimal polymerization temperature for GMA, MAA, Aam and GMA/MAA (8:2), respectively, maximum polymerization of GMA/MAA (2:8), Aam/MAA (8:2) and Aam/MAA (2:8) occurred at 75°C. The polymerization reaction proceeded initially very fast then levelled off irrespective of the monomer or monomer mixtures used. However, the magnitude of the polymer add‐on at levelling off of polymerization followed the order GMA > GMA/MAA (2:8) ≥ GMA/MAA (8:2) > Aam/MAA (2:8) ≥ MAA ≥ Aam/MAA (8:2) > Aam. The polymer add‐on enhanced by increasing the H2O2 concentration up to a certain limit and then decreased. The same situation was encountered with respect to thioureadioxide concentration. The involvement of the epoxy ring of GMA with MAA during polymerization of their mixture with cellulose occurred only at a higher ratio of GMA in the mixture. Also a significant contribution of Aam in the polymer add‐on obtained with a Aam/MAA mixture could only be achieved at a higher ratio of Aam in this mixture.
Catalytic effect of nickel metal and some of its compounds on the aqueous polymerization of methyl methacrylate
Authors: Moustafa A. B. , Rabie A. M. , Badran A. S.
Published: April 2003

Polymerization of methyl methacrylate (MMA) in water was carried out in presence of nickel metal powder, some of its oxides and salts at temperatures of 40, 50, and 60°C using sodium bisulfite as an initiator. It has been found that nickel metal powder retards the polymerization reaction, and increases the apparent activation energy from 6.4 kcal/mol to 13.3 kcal/mol, while nickel salts and nickel oxides were found to catalyze the polymerization process. Nickel nitrate was found to have the highest catalytic effect and resulted in the formation of the least average molecular weights. Nickel sulfate resulted in obtaining the least salt catalytic effect and the highest average molecular weight.
Polymerization of lactams, 43. Hydrolytic copolymerization of 6‐caprolactam with 12‐dodecanelactam
Authors: Alijev Rizo , Kondelíková Jaroslava , Moucha Antonín , Králíček Jaroslav
Published: April 2003

The copolymerization of 6‐caprolactam with 12‐dodecanelactam with 2 mol‐% 6‐aminocaproic acid as the initiator was investigated at 260°C within a broad concentration range of both comonomers. With increasing content of 12‐dodecanelactam in the initial mixture the equilibrium content of the copolymer increased and the rate of copolymerization decreased. In the initial stage of copolymerization 12‐dodecanelactam disappeared very quickly from the initial mixture; it was not incorporated into the copolymer directly, but through oligomers, probably through a cyclic dimer.

The effect of temperature on the copolymerization process was examined for an equimolar composition of the initial mixture. It was demonstrated that starting with the polymerization temperature of 260°C, the copolymers underwent degradation on long‐termin heating. At 280°C, degradation occured already after 50 h of polymerization. The apparent activation energy of copolymerization, 62 kJ/mol, was calculated from the temperature dependence.
Styrene‐divinylbenzene copolymers, IV. Structure and texture changes during synthesis
Authors: Chung David‐Y. D. , Bartholin Michel , Guyot Alain
Published: April 2003

Styrene‐divinylbenzene macroporous resins were prepared with the same composition (13% DVB), but varying diluent amount of benzyl alcohol. From sample analysis, the copolymerization kinetics concerning both monomer consumption and residual double bond amount were determined. Porous texture and morphology analyses by BET

Brunauer, Emmett, Teller.

, BJH

E. P. Barrett, L. G. Joyner, P. P. Halenda, J. Am. Chem. Soc. 73 (1951) 373.

, Mercury porosimetry, and scanning electron microscopy were carried out, too. Depending on diluent amount, the final product is classified as inside or outside the macroporous domain. Texture evolution is clearly different for the two classes of products, although their chemical evolutions are almost the same. A qualitative discussion of porous texture formation is presented, based on occurrence of three critical events: gelation, phase separation and molecular overlap.
Effect of solvents and chain transfer agents on grafting on polyethylene films
Authors: Ivanova Latinka , Boudevska Hrisanta
Published: April 2003

Photosensitized and with UV‐light irradiated low‐density polyethylene was crosslinked and grafted with methacrylic acid at 95 and 96°C in the presence of toluene and chain transfer agents like tert‐dodecyl mercaptan and carbon tetrachloride.

The effect of the concentration of toluene and of chain transfer agents on the graft level has been studied. The graft level can be regulated varying the concentration of toluene and chain transfer agents.

Low electrical resistance was obtained at a low concentration of the chain transfer agent and 30% toluene in methacrylic acid. Pore sizes and tensile strengths change in wider range by grafting in the presence of toluene than using chain transfer agents.
A generalized computer simulation model for obtaining sol‐gel distributions in infinite polymeric networks
Authors: Swaminathan V. , Madhavan N. S. , Sukumaran Nair C. G.
Published: April 2003

Computer simulation is well‐known to be a very efficient and powerful tool, applicable to a wide variety of situations. The present paper is concerned, in some detail, with a computer simulation model for obtaining the sol and gel fractions in polymeric networks. Apart from yielding the values of these parameters, even in situations that are characterized by a considerable amount of complexity, and where, as a consequence, the relevant mathematical procedures have not yet reached a stage of finality, the model developed in this paper can be of value in arriving at a satisfactory overall perspective of the chemical process as a whole. It yields results which enables one to answer such questions as where a crosslinking can occur or how the sol is distributed. Appropriate modifications that are called for in the model in investigating more complex situations are also indicated in the paper.
Polymerization of allyl methacrylate with nylon 6 using benzoyl peroxide as initiator
Authors: Khalil M. I. , Abdel‐Hay F. I. , Hebeish A.
Published: April 2003

Polymerization of allyl methacrylate with nylon 6 using benzoyl peroxide as initiator was carried out under different conditions. The polymer add‐on was dependent upon allyl methacrylate and benzoyl peroxide concentrations, polymerization time and temperature as well as addition of metallic salts or organic solvents. The polymer add‐on increased by increasing benzoyl peroxide concentration up to 0.5 mmol/l then decreased by further increase in peroxide concentration, whereas it increased as the allyl methacrylate concentration increased from 80 – 300 mmol/l. A polymerization temperature of 85°C constituted the optimal temperature, below or above this temperature resulted in lower polymer add‐on. The effect of polymerization time was related to the polymerization temperature, no induction period occured at 95°C in contrast to 15 and 30 minutes at 85°C and 75°C, respectively. The incorporation of Cu+ +ions in the polymerization system improved the magnitude of polymer add‐on. A similar situation was encountered with Fe+ + + and Li+ ions. Using a water/organic solvent mixture as a polymerization medium was advantageous in enhancing polymer add‐on provided that the organic solvent did not exceed 1% in case of ethanol and isopropanol and 4% in case of methanol.
Effect of cations and anions of some metal salts in the aqueous polymerization of methyl methacrylate
Authors: Moustafa A. B. , Badran A. S.
Published: April 2003

It has been found that the catalytic effect of the salts of some metals (copper, iron, nickel, cobalt, manganese and sodium) on the aqueous polymerization of methyl methacrylate initiated by sodium bisulfite) is attributed to the cations as a major catalytic effect and to the anions as a minor catalytic effect. The highest average molecular weights were those obtained in presence of sodium salts and the least average molecular weights were those obtained in presence of copper and iron salts.
Bestimmung von starker neben schwacher säure in polyurethan‐dispersionen mit SO‐ und COO− ‐gruppen
Authors: Lorenz O. , Breidenich N. , Denter U. , Reinmöller K.‐H. , Rose G.
Published: April 2003

Es wurden Dispersionen von Polyetherurethanionomeren mit einem bekannten Gehalt an SO‐ und COO−‐Gruppen hergestellt. Nach Kationenaustausch der Dispersion gegen H+ läßt sich der Gehalt an starker und schwacher Säure durch konduktometrische Titration mit NaOH insbesondere in Gegenwart eines Neutralsalzes (KBr) quantitativ bestimmen. Potentiometrisch wird in Gegenwart von KBr die Summe an starker und schwacher Säure quantitativ erfaßt, nicht jedoch die Einzelanteile, da sich ein Teil der COOH‐Gruppen wie starke Säure verhält. Der KBr‐Zusatz erhöht insbesondere die Säurestärke der starken Säure und verbessert dadurch die Erkennung der Endpunkte. Nach Kationenaustausch gegen Ag+ läßt sich die Summe an starker und schwacher Säure durch konduktometrische Titration mit NaCl bestimmen, da der Ionenaustausch gegen Ag+ quantitativ verläft. COO−‐Gruppen lassen sich durch konduktometrische Verdrängungstitration mit HCl erfassen.

Die bei der Synthese gebildeten Polyelektrolyte können nach Ausfrieren der Dispersion mit den genannten Verfahren im Serum bestimmt werden. Die Abtrennung der Polyelektrolyte mit COO−‐Gruppen durch Anionenaustausch verläuft im Gegensatz zu Polyelektrolyten mit SO‐Gruppen im allgemeinen nicht quantitativ.
Surfactant properties of unsaturated polyesters
Authors: Yu Y.‐Ch. , Funke W.
Published: April 2003

The emulsifying properties of unsaturated polyesters (UP) have been studied. The composition of the UP was varied between ratios of ester groups/carbon chain atoms of 1:3 and 1:5. Surfactant properties of UPs are limited to a certain range of molecular weight, which depends on the UP structure. Aqueous solutions of potassium or triethylammonium salts of the UP solubilize lipophilic monomers like styrene. Depending on the method of emulsifying, normal or multiple emulsions were obtained. By continuous agitation or more rapidly by ultrasonic treatment the multiple emulsion may be transformed to a normal emulsion.
Modified phenol formaldehyde‐(s‐triazine)‐poly(methyl methacrylate) copolymer
Authors: Jayabalan M.
Published: April 2003

A modified phenol formaldehyde‐(s‐triazine)‐PMMA copolymer was prepared to blend polymers which will withstand the adverse effect of UV, vacuum, and heat. The copolymer was characterized for its stability under UV, vacuum, and heat. Crosslinking was found to occur both in UV, vacuum, and thermal exposure. It was detected from the solubility and swelling value. The stabilizing effect of PMMA, the s‐triazine ring, and Phenol formaldehyde was also discussed briefly.
Immobilisierung von corynebakterium simplex in thioliertem polyvinylalkohol zur mikrobiologischen steroidumwandlung
Authors: Manecke Georg , Beier Wilfried
Published: April 2003

Polyvinylalkohol wurde durch polymeranaloge Reaktion mit 3‐Mercaptopropionsäure zu einem zum Einschluß von Mikroorganismen geeigneten Polymeren derivatisiert.

Die Eignung des Polyvinylalkohol‐Derivats zur Immobilisierung von Mikroorganismen wurde mit Corynebakterium simplex (A.T.C.C. 6946) überprüft. Mit den Immobilisaten, die Steroid‐Δl‐Dehydrogenase‐Aktivität zeigten, wurde Hydrocortison zu Prednisolon dehydriert.

Die Δl‐Dehydrogenase‐Aktivität der immobilisierten Zellen erhöhte sich durch Enzyminduktion mit Hydrocortison.

Die Aktivität der Immobilisate wurde in Abhängigkeit von der Zell‐, Substrat‐ und Cofaktorkonzentration, des pH‐Wertes und der Temperatur untersucht.

Die Halbwertszeit der Immobilisate wurde mit und ohne Nährmedium bestimmt. Die Aktivität der Corynebakterium simplex‐Immobilisate betrug 200 μmol · g−1 h−1.
Stark basische, guanidinium‐ionen enthaltende ionentauscher
Authors: Schindlbauer Hellmuth , Anderer Johann
Published: April 2003

Polyethylenimin reagiert in saurer Lösung mit Guanidiniumsalzen zu wasserlöslichen Polymeren, bei denen hauptsächlich die primären Aminogruppen durch Guanidinium‐Ionen ersetzt sind. Bei Vernetzung dieser Makromoleküle mit Formaldehyd entstehen stark basische Ionentauscher mit hoher Kapazität, die auch Aniontenside aus wässerigen Lösungen zu entfernen vermögen.
Effects of lead salts on thermal poly(vinyl chloride degradation)
Authors: Nagy Tibor Tamás , Turcsányi Béla , Kelen Tibor , Tüdős Ferenc
Published: April 2003

The effect of lead salts (lead stearate, tribasic lead sulfate and tribase/stearic acid) on the thermal degradation of PVC was studied in trichlorobenzene (TCB) solution and under dynamic conditions in a mixing chamber. It was established that lead stearate directly reduces the HCl elimination rate (mainly by diminishing the zip length) whereas the tribase is acting only as HCl acceptor. In presence of stearic acid the tribase becomes a true stabilizer.

At the end of the induction period rapid increase of the zip length and transiently high HCl elimination rates were observed. The consequences of these on the possible mechanism of stabilization are discussed.
Modification change during spherulitic growth of polypropylene
Authors: Varga Jozsef
Published: April 2003

Isothermal crystallization of polypropylene in two temperature steps has been investigated by means of polarizing optical microscopy. On the edges of growing β‐spherulites a β → α modification change is observed when the temperature is raised beyond 140°C. The growth rate of the β‐modification exceeds that of the β‐modification above this temperature. Kinetic conditions are, therefore, attained for the β → α transition. Altering the crystallization conditions (T < 140°C) the α → β transition can also be induced. The modification change gives rise to the formation of characteristic twin‐spherulites. The boundary of the modifications corresponds to the shape of limacon of Pascal. Regions of the modifications developed at two different temperatures in a twin‐spherulite show separate melting.
Copolymerization of 2,6‐dimethoxy‐ and 2,6‐dimethylphenol and effect of the copolymer structure on the thermodynamic properties in the solid state
Authors: Jauhiainen Tuure‐Pekka
Published: April 2003

2,6‐Dimethoxyphenol and 2,6‐dimethylphenol have been copolymerized using the Ag2O‐triethylamine complex as catalyst. The products are random copolymers with wide molar mass distributions, M̄w/M̄n from 2.3 to 3.5. The larger size of the methoxy group than that of the methyl group has no effect on the reaction rate.

The heat capacities of the copolymers can be calculated from the values of the homopolymers to an accuracy of within ± 1% from 160 to 280 K.

ΔCp at Tg for the copolymers changes linearly from the value of poly(oxy‐2,6‐dimethoxy‐1,4‐phenylene) to that of poly(oxy‐2,6‐dimethyl‐1,4‐phenylene) and the glass transition temperatures of the copolymers can be described by the equation of Couchman:

\documentclass{article}\pagestyle{empty}\begin{document}$${\rm K} = \Delta {\rm C}_{{\rm p} 2} / \Delta {\rm C}_{{\rm p} 1}.$$\end{document}
Effect of bromine and phosphorus substituents on the glass transition properties of some substituted poly(oxy‐1,4‐phenylenes)
Authors: Jauhiainen Tuure‐Pekka
Published: April 2003

Poly(oxy‐2,6‐dimethoxy‐1,4‐phenylene) and poly(oxy‐2,6‐dimethyl‐1,4‐phenylene) have been modified by addition of bromine‐ and phosphorus‐containing groups to the backbone phenylene rings and the aliphatic side chains. Heat capacities of the pure and modified polymers in the glass transition region have been measured by DSC.

The stiff bromine substitutent in the phenylene ring increases the glass transition points of both homopolymers. The increase follows within experimental error Couchman's equation for mutually miscible polymers. The effect of bromine in poly‐(oxy‐2,6‐dimethyl‐1,4‐phenylene) is considerably greater than in poly(oxy‐2,6‐dimethoxy‐1,4‐phenylene).

The effect of the substitutents on the glass transition points and ΔCp values at Tg of poly(oxy‐1,4‐phenylenes) is discussed.
Modifizierte ozonolyse zur bestimmung von internen doppelbindungen in polyvinylchlorid
Authors: Braun D. , Bezdadea E. , Holzer G. , Sonderhof D.
Published: April 2003

Die Bestimmung der internen Doppelbindungen in PVC ist durch oxidative Spaltung mit Ozon in Tetrachlorethan (TCE)‐Lösung bei − 20°C schnell und einfach möglich, indem die Grenzviskositäten der vor und während der Ozonolyse entnommenen Proben direkt im Reaktionsmedium ermittelt werden. Die zur Berechnung der Molekulargewichte benötigten und mit einer Reihe von PVC‐Eichsubstanzen für TCE ermittelten Konstanten der Viskositäts‐Molekulargewichts‐Beziehung sind K = 0,027 [cm3/g] und α = 0,75. Durch 1H‐NMR‐spektroskopische Untersuchung von Modellverbindungen wie Ölsäure und niedermolekularen Anteilen aus PVC konnte ein Einblick in den Mechanismus der ozonolytischen Spaltung unter den ausgearbeiteten Reaktionsbedingungen erhalten werden.
Molecular weight of polymers. Errors involved in osmotic and viscometric measurements
Authors: Jadraque Daniel , Pereña José
Published: April 2003

The errors associated with the determinations of number average molecular weights through osmotic measurements and intrinsic viscosities through viscometric measurements are calculated by statistical computing. They are compared with the results previously obtained by means of graphical extrapolations, showing the advantages of the proposed method.
Untersuchungen zur struktur von emulsions‐polyvinylchlorid
Authors: Zecha Helmut , Zenke Ingrid , Purz Hans‐Joachim , Bischof Claus
Published: April 2003

Über typische Strukturmerkmale von Suspensions‐ und Masse‐PVC sowie deren Zusammenhang zur Synthese und Verarbeitung ist schon mehrfach berichtet worden, wobei nach Geil Körner, Aggregate, Partikel, Domänen und Mikrodomänen unterschieden werden können.

Unsere elektronenmikroskopischen Untersuchungen beziehen sich auf Emulsions‐PVC‐Pulver, welche durch Sprühtrocknung von wäßrigen PVC‐Latices hergestellt und zur Pastenverarbeitung verwendet werden: Die Pulver‐Körner sind Aggregate aus den Latex‐Partikeln, deren Aufbau durch die Bedingungen beim Sprühtrocknen festgelegt wird. Die Kornstruktur verändert sich infolge der Verpastung und der anschließenden Gelierung. Mit steigender Geliertemperatur zerfallen die PVC‐E‐Körner, die Partikeln ordnen sich dicht gepackt an und verlieren schlierjlich weitgehend ihre Individualität. Infolge der Diffusion des Weichmachers in die Partikeln wird eine Strukturierung der Partikeln in Mikrodomänenbereiche deutlich sichtbar. Für PVC‐Gelate sind die Mikrodomänen das dominierende Strukturmerkmal.
Bestimmung der entmischungstemperaturen von polymerlösungen durch differentialthermoanalyse
Authors: Müssig Bernhard , Wochnowski Horst
Published: April 2003

Die Entmischung von Polymerlösungen zur Bestimmung der Theta‐Temperatur kann über eine Enthalpieänderung verlaufen. Daher wurde zunächst versucht, auf kommerziell erwerbbaren Geräten der Differentialthermoanalyse Phasentrennungswärmen zu registrieren. Da hierbei keine Effekte beobachtet wurden, ist eine neue, dem Problem angepßte Differentialthermomdyse‐Apparatur angefertigt worden. Am Beispiel von Poly‐n‐butylmethacrylat in Isopropanol konnte eine Entmischungstemperatur von 292,6 K bestimmt werden. Dieser Wert stimmt recht gut mit dem aus nephelometrischen Messungen gewonnenen (293,0 K) überein.
Functional monomers and polymers, 98. Asymmetric induction by chiral polymers containing bornyl groups
Authors: Liu Jui Hsiang , Kondo Koichi , Takemoto Kiichi
Published: April 2003

In order to determine the catalytic ability of the polymers containing chiral bornyl groups to the asymmetric induction, the asymmetric addition reaction of dodecanethiol to isopropenyl methyl ketone was studied using synthetic chiral polymers having pendant bornyl groups, in comparison with the case of using a monomeric model compound, i.e. d‐bornyl acetate, and also poly(methyl methacrylate). It was found that the polymers having chiral borynl groups were effective for the asymmetric induction, and the optical yield depended on the bornyl group content in the polymers.