bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of hydrostatic pressure on the electrical conductivity of FEF carbon black‐loaded sbr vulcanizates
Authors: Nasr G. M. , Amin M. , Osman H. M. , Badawy M. M.
Published: April 2003

The electrical conduction was investigated in styrene butadiene rubber (SBR‐1502) loaded with different concentrations of fast extrusion furnace (FEF) black (70, 80, 90, and 100 phr). On the bases of Holm's model, a qualitative description for the electrical conduction through these composites was sought. The pressure coefficient K was calculated and found to be strongly dependent on the carbon black concentrations.
Humidity dependence of the electric characteristics of quaternized 4‐vinylpyridine‐styrene copolymer/perchlorate complexes
Authors: An Heishoku , Hirata Mitsutoshi , Yosomiya Ryutoku , Yaoquan Xin
Published: April 2003

The dependence of electrical characteristics of copolymer complexes on ambient humidity was studied for complexes of quaternized 4‐vinylpyridine‐styrene copolymer/perchlorate complexes. When the 4‐vinylpyridine content in the copolymer increased, a linear decrease in resistivity was found. From this behaviour, it is concluded that the resistivity can be freely set by variation of the 4‐vinylpyridine content in the design of a sensor material. Furthermore, the resistivity was the smallest in the HClO4 complex and successively became large in the order of the KClO4 complex and the LiClO4 complex. From the electrochemical aspect, it was cleared that the degree of dissociation of the counterion exerted influence upon the resistivity of these complexes.
Thermal behaviour of starches and their graft copolymers with polyacrylonitrile
Authors: Patel A. R. , Patel M. R. , Patel K. C. , Patel R. D.
Published: April 2003

Thermal behaviour of twelve different starches and their graft copolymers with polyacrylonitrile (PAN) from granular and gelatinized state, has been examined by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). All the starches exhibit two endotherms around 65 and 260°C and an exotherm around 335°C. The graft copolymer from granular starch shows a weak endotherm around 65°C and an exotherm around 300°C, while gelatinized starch exhibits the characteristic exotherm of PAN at about 250°C along with the exotherm of graft product at 300°C. Scanning electron microscopic studies were carried out to explain the endotherms of starch at 65°C and 265°C. The former one may be due to heat of dehydration while the latter one is attributed to the fusion of crystallites in the starch. Legumine starches seem to have a specific property of retaining moisture even if they are grafted in gelatinized state.
Oxidation of polyethylene in closed mixing chamber
Authors: Fodor Zsolt , Iring Margit , Pukánszky Béla , Kelen Tibor , Tüdős Ferenc
Published: April 2003

The degradation of commercial LDPE was studied under dynamic conditions which simulate the processing. Dynamic oxidation above 140°C is similar to static oxidation under low oxygen pressure both having strong diffusion control. Fragmentation and crosslinking (mainly CC bonds) compete in the process. The hydroperoxides predominate at the beginning of the mixing. Their quantity rapidly decreases while that of oxo groups increases and becomes predominant.

Below 140°C, the conditions are resembling to static oxidation performed under higher oxygen pressure but the process is still somewhat diffusion controlled. The change in the molecular mass is not considerable in the process. The hydroperoxides predominate among the functional groups formed. Their ratio is constant during mixing. The effect of mechanical stress is not considerable.

An increase in the mixing speed resulted in an increase in the rate of the processes studied above.

The higher the total amount of oxygen incorporated in the PE, the smaller is the remaining oxidative stability.
Radiation initiated grafting on fluoro polymers, IV. Influence of morphology and structure of homogeneous and porous PVF2 films on the preirradiation grafting with N‐vinyl‐pyrrolidone in aqueous solution
Authors: Niemöller Axel , Ellinghorst Guido
Published: April 2003

The radiation induced grafting of N‐vinylpyrrolidone in aqueous solution on poly(vinylidene fluoride) (PVF2) films by preirradiation technique using 160 keV electrons has been investigated. Two kinds of homogeneous films have been grafted under the same experimental conditions: unoriented PVF2 films show an isotropic volume increase by grafting and a low saturation grafting yield (SGY): biaxially oriented PVF2 films only increase in their thickness by grafting and reveal a relatively high SGY. This behaviour has been correlated to the morphology of the films. Likewise, porous PVF2 films as obtained by phase inversion process for membrane preparation were grafted under similar conditions as homogeneous films. Porous films prepared from different solvents exhibit different SGYs under given grafting conditions; this phenomenon has been attributed to the structure of the films. Obviously, polymerization is heterogeneous and termination reactions easily take place in the solution containing micropores. The hydrophilicity of the graft membranes increases with SGY. Low grafting yields (up to 7%) lead to an increase in product flux in ultrafiltration experiments and a slightly improved separation of poly(ethylene glycol) solutions especially in the low molecular weight range.
Untersuchungen zur thermodynamischen verträglichkeit von polyethylen hoher dichte (HD PE) und polyethylen niederer dichte (LD PE) in schmelzezustand, II. Die spezifische freie mischungsenthalpie
Authors: Freytag Ulrich , Radusch Hans‐Joachim
Published: April 2003

Aus den Löslichkeitsparametern von HD PE und LD PE wurde ihr temperaturabhängiger Flory‐Huggins‐Wechselwirkungsparameter χ12 und daraus wiederum nach Flory‐Huggins die spezifische freie Mischungsenthalpie ΔGm/V eines HD PE/LD PE‐Systems berechnet. Unter Zuhilfenahme des „reptation”︁‐Modells und der Einstein‐Relation wurde die Diffusionsgeschwindigkeit der PE‐Moleküle abgeschätzt. Die Triebkraft dieser Diffusion ist proportional der spezifischen freien Mischungsenthalphie. Die Ergebnisse zeigen, daß diffusionskontrollierte Entmischungserscheinungen in einer HD PE/LD PE‐Mischung im Schmelzezustand nicht ablaufen. Das bedeutet, daß die Morphologie der Mischungen im Schmelzezustand nur durch die Mischbedingungen im Zusammenspiel mit den Fließeigenschaften der Komponenten festgelegt wird.
Effect of the structure of slightly crosslinked polyurethanes on their thermal stability
Authors: Kościelecka Alicja , Dzierz̊ra Wiesław
Published: April 2003

Polyurethanes slightly crosslinked with allophanate and CC linkages have been prepared by reaction of 4,4′‐diphenylmethane diisocyanate with poly(ethylene adipate) and poly(ethylene maleate) as well as with terephthalic‐adipic copolyesterdiol and some low molecular diols.

Data obtained from isothermal and dynamic thermogravimetric analysis carried out in an inert atmosphere indicate that the thermal stability of polyurethanes is independent on the crosslinking density and the structural characteristics of crosslinks and hard segments.
Oxirane ring opening with imide‐acids
Authors: Soler Héctor , Cádiz Virginia , Serra Angels
Published: April 2003

A study with model compounds was made by 13C‐NMR in order to confirm the two possible sites of attack on an oxirane ring by a carboxylic acid serie. In all cases the presence of signals corresponding to normal and abnormal opening of the ring was detected. Thus, two different methods to quantify the obtained primary and secondary alcohol amounts were used. It was found that the less primary alcohol was obtained the more nucleophilic the carboxylic acid is.
Solute permeation through perfluorocarboxylate membranes
Authors: Kawagoe Jun , Satoh Mitsuru , Iijima Toshiro
Published: April 2003

The sorption and permeability of tetraalkylammonium chlorides and alkali chlorides in perfluorocarboxylate membranes were determined. The water content and density of the membranes were found to change with treatment in boiling water and with different tetraalkylammonium cations as counterions for the carboxylate fixed charge. This is attributed to a change in the structure of the membrane matrices. DSC measurements suggested the existence of three distinct phases in the membranes, i.e. a free water phase, a bound water phase, and nonfreezable water. The nonfreezable water was assumed to be in the fluorocarbon phase. The permeability sequence of the tetraalkylammonium chlorides was found to be TEACl > TMACl > TBACl. To interpret the results, a parallel permeation model was proposed.
Reaction of cellulose‐poly(glycidyl methacrylate) with methylamine
Authors: Abo‐Shosha Mohamed Husein Hassan , Ibrahim Nabiel Abd El‐Basset
Published: April 2003

Cellulose‐poly(glycidyl methacrylate) copolymer was reacted with methylamine. Factors affecting the reaction, such as methylamine concentration, liquor‐to‐material ratio, pH, temperature, and time were studied. The general kinetics of the process was reported, and a mechanism of the reaction was suggested. Potentiometric titration of the product showed that it was a weak base anion exchanger having a pKb of 7.4.
Solution properties of ultrahigh molecular weight polymers, 15. A viscometric study of poly(isobutyl methacrylate) in different solvents
Authors: Simionescu Bogdan C. , Ioan Silvia , Flondor Aurelia , Simionescu Cristofor I.
Published: April 2003

The paper extends previous studies on ultrahigh molecular weight synthetic polymers. The intrinsic viscosities and the viscosity constants of poly(isobutyl methacrylate) fractions were obtained by the methods of Huggins, Kraemer, Martin, Schulz‐Blaschke, and Fedors in CCl4 and C6H6 at 25°C. It was observed that the method of Fedors is not very sensitive to the possible errors appearing in estimating the relative viscosities in higher concentration domains. This method yields intrinsic viscosity values close to the mean values obtained from the other five methods and to the values calculated according to the averaging procedure suggested by Sakai. The transition concentrations separating the concentration domains (diluted‐semidiluted) and the Mark‐Houwink constants were obtained.
Radiation grafting of hydrophilic monomers onto poly(4‐methylpentene‐1), II. Grafting of long chain monomers and physical properties of the grafted films
Authors: Soebianto Yanti S. , Yoshii Fumio , Makuuchi Keizo , Ishigaki Isao
Published: April 2003

Radiation grafting of 2‐hydroxyethyl methacrylate (HEMA) and methoxytetraethyleneglycol methacrylate (M4G) on low crystallinity poly(4‐methylpentene‐1) (TPX) has been investigated. Grafting yield increased with increasing pre‐irradiation dose, grafting temperature, and monomer concentration. Grafting rate depends on length of molecular chain in the monomers and decreases with increasing chain length. The grafting yields of electron beam irradiated samples were higher than those of γ‐irradiated ones because of higher radical concentration. Tensile strength of the grafted film in the dried state increased and the elongation at break decreased with increasing degree of grafting. On the other hand, in the wet state, the tensile strength and elongation at break decreased with increasing the degree of grafting due to the lack of hydrogen bonds between the grafted chains caused by increased water absorption.
Properties of the polyacrylic acid resin duolite es 346 containing amidoxime anchor groups with respect to the separation of uranium from sea water
Authors: Lieser K. H. , Erboy M. , Thybusch B.
Published: April 2003

Loading curves, rate of exchange and distribution coefficients of Duolite ES 346 are determined for UO22+, Cu2+ and Fe3+, using simulated sea water. The crude resin gives off ammonia into solution which leads to precipitation of uranyl ions and high apparent distribution coefficients. With the purified resin the following distribution coefficients are measured at pH 8.1: Kd(UO22+) ≈ Kd(Cu2+) ≈ Kd(Fe3+) ≈ 0.6 · 104 ml/g. This leads to a loading of the resin in sea water of pH 8.1 with uranium only to about 20 μg per g of resin.
Sorbents prepared from a composite reactive carrier based on bead cellulose and poly(ethylenemethacrylate‐toluenesulfonate)
Authors: Lenfeld Jiří , Štamberg Jiří
Published: April 2003

A composite reactive carrier consisting of bead cellulose and poly(ethylenemethacrylate‐toluenesulfonate) was modified by reactions with sodium sulfite, dimethylaminoethanol, polyethyleneimine, thiourea (followed by hydrolysis with KOH), phenol, and pyrogallol (followed by mercuration with mercury(II) acetate (CH3COO)2Hg) to functional sorbents containing sulfonic, quaternary ammonium, imine, thiol, and Hg+ ion exchange groups. The modification is accompanied by a hydrolytic splitting‐off of the reactive tosyl group. The hydrolysis is supported by the presence of water in the reaction medium and its degree increases with the reaction temperature. The highest conversion was reached in the formation of the thiol sorbent. Its sorption properties were investigated by the sorption of Ag+ ions. The observed high rate of sorption is a consequence of the hydrophilizing effect of the cellulose component of the composite sorbent.
Synthesis and properties of 4‐vinyl pyridine grafted SBS used as charged mosaic membrane
Authors: Hsiue G. H. , Yeh Z. K.
Published: April 2003

The grafting of 4‐vinyl pyridine onto styrene‐butadiene‐styrene triblock copolymer by irradiation was studied. Cationic and anionic groups were introduced by sulfonation and methylation to obtain a charged mosaic membrane.

The experiments showed an increased rate of grafting with the increase of irradation dose. The best concentration of monomer was at 20%.

After grafting, the contact angle and the water content were tested and morphology studies were performed.

Furthermore, the tensile strength of this membrane increased with increased percentage of grafting. After testing, the charged mosaic membrane had a reduced potential. Its anionic and cationic exchange capacitites were between 0.12 to 0.13 meq/g, and 0.24 to 0.343 meq/g, respectively. The ratio of exchanged capacity was up to 0.509. KCI and urea can be separated by dialysis. In the determination of a piezodialysis, the salt enrichment reached a percentage of 10.3.
Synthesis and properties of polyamine‐imides containing phenoxaphosphine units
Authors: Subramaniam Prema , Srinivasan Mahalingam
Published: April 2003

Polyamine‐imides were synthesized by polycondensation reaction of bis‐N‐methyl‐olimides and diamines. The reactions were carried out in the aprotic polar solvent dimethylacetamide (DMAc) and polymers with inherent viscosities ranging between 0.36–0.75 dl/g were obtained. The polymers were degraded by conc. H2SO4. All the polymers were characterized by elemental analysis, IR‐ and 1H‐NMR spectroscopy, density, solubility, crystallinity, and thermal analysis.
Modified starch‐natural rubber blend, I. Cyanoethylation of xanthated starch
Authors: Hota Arun K. , Adhikari Basudam , Maiti Mrinal M.
Published: April 2003

Common wheat flour starch was subjected to xanthation followed by cyanoethylation at various levels of carbon disulfide and acrylonitrile to prepare modified starchnatural rubber masterbatches. Mutual influences of the extents of equilibrium xanthation and cyanoethylation on each other have been studied. The results have been explained on the basis of a definite interaction between xanthate group and free acrylonitrile in which both the steric factors and higher electrophilicity of acrylonitrile lead to the decomposition of xanthate groups and reduced the extent of cyanoethylation.
Aktivkohle aus Phenolharz mit gepreßten Olivenkernen als Füllstoff
Authors: Simitzis Johannis
Published: April 2003

Eine neue Aktivkohle wurde aus Phenolharz (Novolak‐Typ), gefüllt mit gepreßten Olivenkeren, hergestellt. Letztgenanntes Material ist ein landwirtschaftliches Nebenprodukt, das in großen Mengen jährlich hauptsächlich in Mittelmeer‐Ländern anfällt. Beide Materialien wurden in verschiedenen Verhältnissen gemischt, gehärtet und bis 1000°C carbonisiert. Der Gewichtsverlust und die Schrumpfung der Proben beim thermischen Abbau wurden gemessen. Die spezifische Oberfläche der kohlenstoffhaltigen Rückstände in verschiedenen Formen (z. B. als Pulver oder zylindrische Körper) wurde bestimmt. Die Adsorptionsfähigkeit der hergestellten kohlenstoffhaltigen Materialien in Bezug auf den Farbstoff Methylenblau in wäßrigen Lösungen wurde untersucht, und es wurde festgestellt, daß der Adsorptionsprozeß gemäß der Freundlich‐Gleichung stattfindet.
Oberflächenspannung von Poly(n‐butylmethacrylat)‐und Poly(n‐butyl‐ran‐methylmethacrylat)‐Schmelzen
Authors: Pigłowski Jacek
Published: April 2003

Die Oberflächenspannungen sowie die Temperaturkoeffizienten der Oberflächenspannung von Poly(n‐butylmethacrylat) und zweier Copolymerisate aus Methylmethacrylat und Butylmethacrylat wurden im Temperaturbereich zwischen 180 – 230°C untersucht. Das Vorhandensein von Butylmethacrylatsequenzen in den Copolymeren senkt deutlich die Oberflächenspannung. Die Konsequenzen dieses Verhaltens für die Verwendung von Methacrylatcopolymeren als Verarbeitungshilfsmittel für Hart‐PVC werden diskutiert.
Verträglichkeit zwischen Methacrylat‐homo‐ und Copolymeren
Authors: Pigłowski Jacek , Kozłowski Marek
Published: April 2003

Die Mischbarkeit von verschiedenen Systemen aus Polymethylmethacrylat (PMMA), Polybutylmethacrylat (PBMA) und Poly(methylmethacrylat‐co‐butylmethacrylat) (P(MMA‐co‐BMA)) wurde untersucht. PMMA und PBMA sind miteinander nicht mischbar. Die untersuchten Homopolymeren und entsprechende Methacrylatcopolymere bilden ebenfalls heterogene Systeme. Einphasige Mischungen aus PMMA und PBMA sind nur über Copolymerisation erreichbar.
Ethylene insertion with soluble Ziegler catalysts. III. The system cp2TiMeCl/AlMe2Cl/13C2H4 studied by 13C‐NMR spectroscopy. The time‐development of chain propagation and oligomer distribution
Authors: Mynott Richard , Fink Gerhard , Fenzl Wolfang
Published: April 2003

The development of the oligomer distribution during the polymerization of 13C‐enriched ethylene by the soluble Ziegler catalyst system Cp2 TiMeCl/AlMe2Cl was followed by 13C‐NMR spectroscopy. The assignment of the signals from the growing chains is described in full. It is shown that the rate of consumption of ethylene and Cp2 TiMeCl and the rate of formation of new chains can be monitored directly from the spectra. The concentrations of Ti‐propyl and Ti‐pentyl species during the polymerization were followed spectroscopically; both attain a steady state concentration. The relative rates were determined for the insertion of ethylene in the Ti‐carbon bond of Ti‐Me, Ti‐Pr and Ti‐Pe. These results give a detailed insight into the way that the oligomer distribution develops and provide a basis for its computer simulation. They also provide an independent proof that the dynamic model for the mechanism of ethylene polymerization with soluble Ziegler catalysts of the type Cp2 TiRCl/AlRnClm is correct.
Corrélations entre les propriétés viscoélastiques d'un composite verre‐epoxy et la présence d'un agent de pontage amino‐silane à la surface des fibres
Authors: Chauchard J. , Chabert B. , Jeanne P. , Nemoz G.
Published: April 2003

Dynamic, mechanical, and thermal properties were determined for unidirectional glass fibre reinforced resins. By an out axis study, it is possible to show the particular influence of a silane coupling agent on the mechanical and physical properties of composites. This agent increases the modulus of elasticity, the relaxation times, and the apparent activation energy in the rubbery state.
Synthesis and thermal stability of polyesters and polyamides fromβ‐(2‐methoxy‐5‐methylphenyl) glutaconic acid, diols, and diamines
Authors: Mehta Ashok M. , Dave Harshad R. , Patel Rajni M.
Published: April 2003

Some polyester and polyamide resins were prepared by condensing β‐(2‐methoxy‐5‐methylphenyl) glutaconic acid with diols and diamines. The polycondensates were characterized by IR, TG, DSC, VPO, and elemental analysis. Some polycondensates were found to be soluble in acetone, dimethylformamide, and dioxane. All polymers were found to decompose in the range of ≈200 to ≈600°C. Their softening points are in the range of ≈ 90 to ≈ 190°C. They are brown black in colour. The kinetics of decomposition were studied. The kinetic parameters were evaluated by the method of Broido. It is observed that the energy of activation of polycondensates depends upon the presence of diol and diamine components in the polymer.
Effects of reaction conditions on bromination of atactic poly(propylene)
Authors: Mukherjee Ananda K. , Mohan Anita
Published: April 2003

Effects of various reaction conditions on bromination of atactic poly(propylene) (APP) in carbon tetrachloride solution were studied. It was found that with the increase of the reaction time the extent of bromination increases. Also with an increased dilution of APP the rate of bromination increased following a bromination order of 0.66 with respect to APP concentration. This has been ascribed to initial replacement of the hydrogen at the tertiary carbon atoms followed by enhanced ease of abstraction from the neighbouring secondary and primary carbon atoms. The apparent activation energy was found to be 11.9 kcal/mol. The rate of bromination increases with an increase of the APP: Br2 molar ratio up to 1 : 1, beyond which the rate becomes independent of this ratio. Mechanism of bromination appears to be an initial substitution of tertiary H‐atoms by bromine radicals followed subsequently by replacement of secondary and primary H‐atoms via either progressive substitution or elimination‐addition. IR spectra confirm the presence of bromine in the samples.
Reactive olefinic copolymers. New developments and applications
Authors: Hert Marius , Guerdoux Lionel , Lebez Jean
Published: April 2003

Research work on reactive olefinic copolymers at CdF Chimie, has been followed since 1984 by the commercial development of a family of ethylene‐maleic acid anhydride (MAA) and acrylic ester terpolymers. These terpolymers cover a wide range of grades going from semi‐crystalline thermoplastics to elastomers, depending on comonomer content.

Thus these products have found applications in various fields (coextrusion, lamination, toughening of blends, hot‐melts, powder coating etc.).

Outstanding properties are obtained in several applications owing to the chemical reactivity of MAA with substrates in coextrusion and coating and with polymer matrices in blends. Chemical crosslinking, easy to perform with terpolymers, is a way to improve the high temperature mechanical properties (in wires and cables, pipes, hot‐melts etc.).
Influence of grafting on the thermodynamic parameters and stability constants of some intermacromolecular complexes of poly(methacrylic acid) and a graft copolymer
Authors: Chatterjee Saroj Kumar , Yadav Jai Bhagwan , Sethi Kuldip Raj
Published: April 2003

Stability constants and thermodynamic parameters (e.g. ΔH° and ΔS°) have been determined for intermacromolecular complexes of poly(methacrylic acid) and poly(acrylamide) (PAm)/poly(vinyl alcohol) (PVA) graft copolymer. These values have been compared with those obtained for the intermacromolecular complexes of corresponding homopolymers (e.g. PAm and PVA). Influence of grafting on these parameters has been explained on the basis of more favourable cooperative binding with the graft copolymer.
Analytische Untersuchung einer Polymerlegierung aus Polyamid und Ethylencopolymeren
Authors: Braun D. , Illing W.
Published: April 2003

Aus Polyamid 6 (PA 6) und einem Copolymeren aus Ethylen und Acrylsäure (EAA) wurde im Gewichtsverhältnis 90/10 eine Polymerlegierung in einem Zweiwellenextruder unter dem Einfluß von hohen Scherkräften und Temperaturen hergestellt. Das entstandene Mehrphasensystem aus PA 6, EAA und Pfropfcopolymeren wurde durch REM‐Aufnahmen, DTA, GPC, IR, NMR, Extraktion mit für die Ausgangsprodukte spezifischen Lösungsmitteln und Bestimmung der reaktiven Gruppen untersucht.
Collagen‐based bioadhesive barnacle cement mimic I. Chemical and enzymatic studies
Authors: Kaleem K. , Chertok F. , Erhan S.
Published: April 2003

A biomedical adhesive that can bind to calcified tissues without drying and prior acid etch has been developed. The adhesive was prepared from commercially available gelatin, by first modifying its backbone to increase its phenolic content. This was achieved by reductive alkylation using phenolic aldehydes. Gelatin, modified this way, functions as a substrate for polyphenol oxidase and crosslinking takes place. A concentrated solution of gelatin and the enzyme, together with amines, can bond bone slices.
Matériaux Composites à Base de Bois Rétifié: Contribution à i'Etude des Propriétés Rhéologiques à i'Etat Fondu en Régime Stationnaire
Authors: Jaziri M. , May J. F. , Bourgois J. , Guyonnet R.
Published: April 2003

L'étude des propriétés rhéologiques à l'état fondu de matériaux composites à base de farines de bois ou de bois rétifié et de polyéthylène basse densité apolaire ou de copolymères d'éthylène polaires, a été effectuée à différentes vitesses de cisaillement. Le comportement des mélanges varie avec le degré de torréfaction du bois et la nature polaire ou apolaire de la matrice. Une interprétation de ces différences de comportement, basée sur les interactions fibres‐matrices, a été proposée. Des mesures d'essais mécaniques, effectuées sur des éprouvettes composites, confirment les résultats présentés à l'état fondu.
Synthesis of chiral polymers with pendant aminobornanol derivatives
Authors: Liu Jui‐Hsiang
Published: April 2003

A series of diastereoisomeric amino bicyclo [2,2,1] heptane derivatives was synthesized from ( + )‐camphor. Further treatment of aminobornanols with triethyl orthopropionate yielded chiral oxazolines, which were found to be efficient for the asymmetric induction of carboxylic acids. Synthesis and polymerization of the new chiral oxazolinebornyl methacrylates derived from aminobornanols was carried out. Effects of temperature, solvents, and molar ratio of the reagent on the synthesis of the linear chiral and of the insoluble cross‐linked chiral polymers were also discussed.
Radical copolymerization and terpolymerization of 1,1,2,3,4,4‐hexafluoro‐1,3‐butadiene with alkylvinyl ethers, alkenes, and methyl‐2,3,3‐trifluoroacrylate
Authors: Žůrková E. , Bouchal K. , Kálal J. , Chvátal Z. , Dědek V.
Published: April 2003

Copolymere von 1,1,2,3,4,4‐Hexafluor‐2,3‐butadine (HFB) mit n‐Alkylvinylethern(AVE) (Alkyl = Butyl, Propyl, Ethyl and Glycidyl) order mit Alkenen wie isobuten, Ethylen and Propylen wurden durch radikalische Lösungscopolymerisation unter Verwendung von peroxidischen Neidertemperatureinition synthesiert. Die Polymerisation verlief nach radikalischem Mechanismus and wurse durde durch die Zugable vo 1,2‐Diphenyl‐2‐pikryl‐hydrazyl völling inhibiert. Die Anfangsgeschwindigkeit der Copolymerisation hing von der Gesamtkozentration der Monomeren and von von dem Verhältnis [HFB] zu [AVE] ab; die maximale Reaktiongeschwindigkeit wurde bei etea äquimolaren Konzentrationsverhältnissen der monomeren erzielt.

Durch die untersuchung der Struktur der copolymeren HFB‐AVE wurde die alter‐neirende Anordnung der Hexafluorobutadien‐and Vinylethereinheinten in der Copolymerkette nachgewiesen. Durch die radikalische Lösungsterpolymerisation des Monomerensystems HFN‐AVE Methyl‐2,3,3,‐trifluoracrylet (MTFA) wurden Terpolymere des Typus–[HFB]x‐[AVE]y‐[MTFA]z –synthetisirt, deren Struktur einer alternierrenden Anordnung von Perfluor‐ (HFB and MTFA) and Vinylethereinheiten entspricht. Durch alkalische hydrolyse der Trifluoracrylateinheiten wurden die entsprechenden Terpolymeren der Triflurocrylsäure synthesiert.
Zur radikalisch initiierten Copolymerisation von Ethylen, I. Ethylen‐Propylen‐Copolymerisate
Authors: Payer Wolfgang
Published: April 2003

Wachsartige Copolymerisate aus Ethylen und Vinylacetat werden in der Mineralölindustrie als Fließverbesserer für Mitteldestillate eingesetzt. Es sollte geprüft werden, ob sich mit anderen analog zusammengesetzten Copolymeren die gleichen Effekte erzielen lasen. Hierzu wurde die Copolymerisation von Ethylen und Propylen unter Drücken von 150 und 200 MPa bei Temperaturen von 160 und 200°C untersucht.

Die Initiierung der Reaktion gelingt problemlos durch Peroxide, wobei mit steigendem Propylen‐Anteil im Reaktionsgemisch eine Erhöhung der Initiatormenge erforderlich ist. Die mittlere Molmasse der Produkte ist vom Propylen‐Gehalt abhängig. Sie kann darüber hinaus durch die Verwendung von Kettenübertragungsmitteln gezielt eingestellt werden. Die Ethylen‐Propylen‐Copolymerwachse zeigten im Vergleich zu den analog zusammengesetzten Ethylen‐Vinylacetat‐Copolymerwachsen nur eine begrenzte Wirksamkeit als Fließverbesserer in Mitteldestillaten.
Depolarization current of novolac phenol‐formaldehyde resins doped with 1,4‐diazabicyclo [2.2.2] octane
Authors: Topić Mladen , Moguš‐Milanković Andrea , Katović Zvonimir
Published: April 2003

Mixtures of novolac phenol‐formaldehyde (NPF) resins and 1,4‐diazabicyclo [2.2.2] octane (DABCO) were polarized at different temperatures applying different d. c. electric fields. Thermally stimulated depolarization current (TSDC) measurements performed from 298 to 373 K showed a dipolar α peak and a space charge α peak as in pure NPF. The addition of DABCO decreases the magnitude of the α peak and the activation energy of the dipolar relaxation but increases the background current and the magnitude of the α peak significantly. The maximum of the α peak is only slightly shifted towards higher temperatures. New aspects in the analysis of the background current by consecutive heating and cooling experiments are considered. The results obtained show an increase in concentration of trapping sites due to the heterogeneity of the mixed systems. The proposed interactions between nitrogen from DABCO and hydroxy groups from NPF are discussed.
Determination of ethylene‐propylene rubber in crosslinked blends with 1,4‐polybutadiene
Authors: Hummel Klaus , Stelzer Franz , Hobisch Gerald , Hartmann Barbara
Published: April 2003

Crosslinked blends of ethylene‐propylene rubber (EPR) and 1,4‐polybutadiene (BR) were investigated by metathesis degradation of the BR component; the percentage of EPR was determined by weighing the polymeric residue. The metathesis reaction was carried out with an excess of 1‐octene in the presence of the catalyst WCl6/(CH3)4Sn. In crosslinking with dicumyl peroxide, the best results were obtained with 10 to 30 wt.‐% of EPR and medium crosslinking degrees. Analysis of sulphur vulcanizates (received with the accelerator N‐cyclohexyl‐2‐benzothiazyl sulphenamide) gave tolerable results only for low sulphur contents (1.5 wt.‐%). Determination of EPR was also possible in non‐crosslinked blends with BR.
Fließverhalten von Mischungen aus chloriertem Polyethylen und Polymethylmethacrylat
Authors: Braun P. , Mennig G. , Paredes E.
Published: April 2003

Das Fließverhalten von Mischungen aus chloriertem Polyethylen (PEC) und Polymethylmethacrylat (PMMA) wird in Form von Fließkurven dargestellt. Die Ergebnisse der rheologischen Messungen werden anhand der sich ausbildenden Morphologie diskutiert. Es zeigt sich, daß die untersuchten Mischungen aus PEC/PMMA mit Chlorierungsgraden bis 40 Gew.‐% Cl das charakteristische Verhalten von unverträglichen (2‐phasigen) Mischungen mit teilweise fein dispergierter zweiter Phase liefern. Vergleichend wird die Stoffkombination PE/PMMA betrachtet, wobei die PE‐Sorten jeweils die unchlorierten Ausgangsprodukte darstellen. Der Einfluß der Chlorierung auf das Fließverhalten und die zweiphasige Struktur ist deutlich festzustellen.
The laser flash‐initiated polymerization as a tool of evaluating (individual) kinetic constants of free radical polymerization, 3. Information from degrees of polymerization
Authors: Olaj Oskar Friedrich , Bitai Irene
Published: April 2003

Equations are derived for the number average and the weight average degrees of polymerization for the polymer forming in a laser‐initiated photo‐polymerization under pseudostationary conditions when termination occurs by disproportionation or recombination and if chain transfer is negligible. Analysis of the degrees of polymerization at various pulse separations leads to information on the rate coefficient of propagation (kp) and on the product kt ρ (kt = rate coefficient of bimolecular chain termination, ρ = concentration of primary radicals produced in each flash). As kp2/kt may be evaluated from the rate and the weight average degree of polymerization P̄w of a single pseudostationary experiment, at least in principle, a complete resolution into individual constants may be achieved. It is demonstrated in an example that the data obtained in this way for the polymerization of styrene at 25°C are well consistent with those originating from other methods.
Gemeinsame Kondensation von Harnstoff, Melamin und Formaldehyd. II. Modellreaktionen
Authors: Braun Dietrich , Ritzert Hans‐Josef
Published: April 2003

Anhand von Modellreaktionen von teilweise blockierten Melamin‐ und Harnstoff‐derivaten mit Formaldehyd wurde die gemeinsame Kondensation von Harnstoff, Melamin und Formaldehyd studiert. An den Modellsystemem Harnstoff/Benzoguanamin/Formaldehyd und Dimethylharnstoff/2‐Amino‐4,6‐di‐(N‐methylanilin)‐1,3,5‐triazin/Formaldehyd konnten mit Hilfe der Gelchromatographie, IR‐Spektroskopie und Thermogravimetrie chemische Brücken zwischen den Triazin‐ und Harnstoffkomponenten, also Cokondensate, festgestellt werden.

Auch beim System Harnstoff/Melamin/Formaldehyd konnten durch Pikratfällung der Triazinkomponenten und Urease‐Spaltung dieses Niederschlages Cokondensate nachgewiesen werden.
Small‐angle X‐ray investigations of defined multiblock (b‐styrene‐bisphenol a carbonate) copolymers
Authors: Włochowicz Andrzej , S̀lusarczyk Czesław , Strobin Grażyna , Dems Andrzej
Published: April 2003

The separation of phases in defined multiblock (b‐styrene‐bisphenol A carbonate) copolymers was analyzed by small‐angle X‐ray scattering. It was found that these copolymers form typical microdomain structures. For copolymers containing 0.34 and 0.47 wt.‐parts polycarbonate (PC) the microdomains are arranged in the face‐centred cubic macronetwork. The distance between domains decreases with increasing concentration of polycarbonate. The copolymer containing 0.767 PC has lamellar structure. The thickness of the domain‐boundary interphase was quantitatively estimated by analyzing a systematic deviation of the scattering curves at large angle tail from the Porod's law. The thickness of the transition layer decreases with increasing concentration of polycarbonate.
Antioxidants and stabilizers, 107. Reaction of N‐phenyl‐1,4‐benzoquinoneimine with the 1‐cyano‐1‐methylethyl‐radical
Authors: Taimr Luděk , Prusíková Miluše , Hanuš Vladimír , Pospíšil Jan
Published: April 2003

The reaction of N‐phenyl‐1,4‐benzoquinoneimine (I)

Decoding of abbreviations see p. 103/104.

and 4‐hydroxydiphenylamine (II) with the carbon centred 1‐cyano‐1‐methylethyl radical (R·) was studied in connection with an investigation of the action mechanism of industrial antidegradants, such as N‐phenyl‐N′‐sec‐alkyl‐1,4‐phenylenediamines. The mixture of I and II reacts very readily with R·, giving rise to III, VI, and VIII. I alone reacts much slowlier, and the reaction mixture contains more products. IV and VII were identified along with III. Under the conditions used, II alone does not react at all. IV exists in two isomeric forms, syn and anti. VIII is very labile; XI was isolated from its transformation products. Reduction of IV gives V, which is labile, similarly to VIII.
On the structure of macroreticular styrene‐divinylbenzene copolymers
Authors: Poinescu Ignat , Vlad Cristina , Carpov Adrian , Ioanid Aurelia
Published: April 2003

The influence of the removal of various diluents, pore forming agents from the porous styrene‐ethylstyrene‐acrylonitrile‐divinylbenzene copolymers on the structure of the matrix was investigated by several methods. The most advantageous pathway to preserve the initial structural edifice of the porous networks performed in the presence of solvating diluents consisted in the removal of the inert media with methanol as it was noticed from the experimental data. If the steam treatment is applied, the collapse effect takes place and the anion exchangers prepared from such matrices exchange/adsorb less dye stuff by comparison with ones formed from beads treated with methanol, because the pore size was changed. It was also noticed that the porous copolymers performed in the presence of the solvating diluents (mixtures of solvatings and precipitants) swell very well in methanol though it is a precipitating medium for the polystyrenic macromolecular chains.
Ozoninduzierter Abbau von Polyoxymethylen
Authors: Braun D. , Müller I.
Published: April 2003

Proben von unstabilisiertem und mit den Antiozonantien N‐Isopropyl‐N′‐phenyl‐p‐phenylendiamin (IPPD) und Bis‐(1,2,3,6‐tetrahydrobenzaldehyd)‐pentaerithrityl‐acetal (Vulkazon AFS) stabilisiertem Polyoxymethylen wurden unter mechanischer Belastung in einer Klimakammer ozonisiert. Die Schädigungen auf der Oberfläche wurden IR‐spektroskopisch und rasterelektronenmikroskopisch untersucht. Während der Ozonisierung von POM bildet sich eine geschädigte Schicht, deren Dicke mit zunehmender Ozonisierungszeit wächst. Hierbei wird das Polymere an den Acetalbindungen angegriffen, wodurch Ketten gespalten werden und Oligomere entstehen.
Heat stability of styrene‐zinc acrylate copolymers
Authors: Włochowicz Andrzej , Eder Marek
Published: April 2003

The dependence of glass temperature on the heating rate and the composition for styrene‐zinc acrylate copolymers has been investigated by differential scanning calorimetry. Thermogravimetry was used in order to examine these copolymers undergoing pyrolysis in an atmosphere of air at three different heating rates. Thermal decomposition of ionomers is a three‐stage process. The orders and activation energies have been determined for each stage of decomposition using the computer programs based on the methods of Kissinger, Freeman‐Carrol, and Ozawa. It was found that the heat stability is lowered by the ionic groups.
Light scattering studies of aqueous solutions of a new flocculation agent from polyacrylonitrile and dicyandiamide
Authors: Dautzenberg Herbert , Gohlke Ulrich , Rother Gudrun
Published: April 2003

The molecular parameters of the flocculation agent from polyacrylonitrile and dicyandiamide (PAN‐DCD) were determined in dimethylsulfoxide. In acidic and alkaline aqueous solutions (0.1 N) PAN‐DCD is weakly aggregated, additionally a small fraction of polymer exists as highly aggregated particle component. A shift of the pH‐value in direction to the neutral range leads immediately to particle growth, which is finished at pH 3, coming from the acidic range and pH 10, coming from the alkaline one. After the passage of the neutral range disaggregation occurs. Flocculation can also be induced by addition of salt.

The structural parameters of the particles were determined by a detailed analysis of the light scattering curves. Results obtained give information about the flocculation mechanism.
Highly dispersed Ni catalysts on carbon from thermal decomposition of cellulose‐hydrous nickel gel membrane
Authors: Ishiyama Jun‐ichi , Shirakawa Tetsuo , Kurokawa Yoichi , Imaizumi Shin
Published: April 2003

Ultra fine particles were impregnated by using a finely porous cellulose gel membrane. The impregnated gel membrane is a green transparent one and looks like a solid solution. Highly dispersed Ni catalysts on carbon were obtained from thermal decomposition of these gel membranes. The particle size is in the range of several nm to a few ten nm. They show interesting catalytic properties for hydrogenation of olefins such as cyclooctadiene.
Selective ethylene adsorbent composed of copper(I) chloride and polystyrene resin having tertiary amino groups
Authors: Komiyama Makoto , Kurima Kazunori , Hirai Hidefumi
Published: April 2003

Selective adsorbent for ethylene is prepared from copper(I) chloride and a macroreticular type polystyrene resin having tertiary amino groups. The adsorbent rapidly adsorbs ethylene at 20°C under 1 atm. The adsorbed ethylene is readily desorbed by subjecting the adsorbent to a reduced pressure (3 mm Hg) at 20°C. The ethylene adsorbing capacity of the adsorbent is 5.5 times as large as the adsorbing capacity for ethane. The present adsorbent exhibits no measurable adsorptions of nitrogen and hydrogen at 20°C under 1 atm, and thus is applicable to selective separation of ethylene from mixtures containing these gases and ethane.
Styrene‐divinylbenzene copolymers. VI. Porosity formation in the presence of toluene‐cyclohexanol mixtures as inert diluents
Authors: Okay Oǧuz
Published: April 2003

Porosity formation by suspension copolymerization of styrene‐divinylbenzene (S‐DVB) in toluene‐cyclohexanol mixtures was investigated. The total porosity of the copolymers increases and their volume swelling ratio in toluene decreases as the DVB concentration in the starting monomer mixture increases and the solvating power of the polymerization medium decreases. The volume fraction of the diluent separated out of the network phase, vD, was found to be constant after passing a critical amount of DVB and the diluent. The limiting value of vD is only dependent on the solubility parameter difference of the polymer and the diluent. Thus, if sufficient amounts of DVB and diluent are present during the network formation, the maximum porosity of S‐DVB copolymers can be predicted from the solubility parameters of the components.
Styrene‐divinylbenzene copolymers. VII. Stability of the porous structures formed in toluene — cyclohexanol mixtures
Authors: Okay Oǧuz
Published: April 2003

The pore stability of styrene‐divinylbenzene (S‐DVB) copolymers prepared in toluene‐cyclohexanol mixtures as inert diluents was investigated as a function of the DVB concentration, diluent composition, and dilution. The stability of the porous structures increases with increasing DVB concentration and, to some extent, with increasing dilution. At a fixed degree of equilibrium volume swelling in toluene, the pore stability also increases with increasing with increasing solvating power of the diluent. The density of S‐DVB copolymers increases during the sulfonation reaction with chlorosulfonic acid, but the stability of porosity remains unchanged.
Zero‐shear viscosity of dilute to moderately concentrated solutions of cellulose acetate phthalate
Authors: Sinha Vijay K. , Patel Kirit H. , Trivedi Harikrishna C.
Published: April 2003

The zero‐shear viscosities of dilute to moderately concentrated cellulose acetate phthalate solutions in DMF were measured at different temperatures and the viscosity data were analyzed in terms of Martin's and Fedor's relationships. The [η] values obtained due to the relationships of Martin and Fedor were found to be in very good agreement. The viscosity‐concentration data were also generalized in terms of reduced variables. The temperature dependence of viscosities was expressed by the Frenkel‐Eiring equation and the free energy of activation (ΔGv), heat of activation (ΔHv), and entropy of activation (ΔSv) of the viscous flow of polymer solutions were calculated. It has been observed that the activation energy for viscous flow increases and the activation entropy decreases with concentration of polymer solutions.
Copolymerization of acrylonitrile with maleamic acid derivatives and with carboxyphenylmaleimide
Authors: Elsabee Maher Z. , Mikhael Michael G. , Sabaa Magdy W. , Yassin Ahmady A.
Published: April 2003

Acrylonitrile was copolymerized with two N‐arylmaleamic acids and with N‐3‐carboxyphenylmaleimide in dimethylformamide (DMF) using azobisisobutyronitrile as initiator. The reactivity ratios and the Q‐e parameters of these monomers were estimated, and the resulting copolymers were characterized by viscosity measurements and thermal analysis. Thermogravimetry and differential thermal analysis data showed an improvement in the thermal behaviour of the investigated copolymers compared with that of poly(acrylonitrile). Mechanisms illustrating the role of both the acidic group and the maleimide ring in the nitrile oligomerization were proposed. The produced copolymers showed an excellent affinity towards basic dyes and better color fastness towards UV light.
Cyclodehydration of bismaleamic acids
Authors: Varma I. K. , Tiwari Ranjana
Published: April 2003

The paper describes thermal and chemical cyclodehydration studies of bismaleamic acids prepared by reacting 4,4′‐diaminodiphenyl methane (DADPM), 4,4′‐diaminodiphenyl ether (DADPE), and 3,3′‐diaminodiphenyl sulfone (DDS) with maleic anhydride and 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride. Thermal cyclisation was carried out by heating the bismaleamic acids at 120 – 140°C for 1 – 4 h. Chemical cyclisation was carried out by treating the bismaleamic acids with NaOAc/Ac2O to give bismaleimides BTM, BTE, and BTS, respectively. The products of thermal and chemical cyclisation were characterized by determination of acid number. Percentage conversion of bismaleamic acid to imide was found to be higher at higher temperatures for the same duration of thermal treatment. Elemental analysis and acid number indicated incomplete cyclisation of bismaleamic acid on thermal treatment. IR spectra of samples confirmed the disappearance of amide groups on cyclodehydration. In DSC traces of bismaleamic acids a broad endothermic peak due to imidization reaction was observed. Thermogravimetric analysis of uncured and isothermally cured samples was carried out in nitrogen atmosphere. Improvement in thermal stability was observed on curing.
Studies on aqueous polymerization of acrylonitrile. Peroxodisulfate‐thiourea redox system
Authors: Misra M. , Mohanty A. K. , Singh B. C.
Published: April 2003

An investigation on kinetics of aqueous polymerization of acrylonitrile (AN) initiated by peroxodisulfate‐thiourea redox system has been carried out in the temperature range of 40° to 50°C. The concentration effect of thiourea, monomer, peroxodisulfate on polymerization rate and percentage of conversion has been studied. The effect of some inorganic salts and different organic solvents on polymerization rate has also been investigated. The isolated polymer has been characterized by IR spectra. A suitable kinetic scheme has been proposed and appropriate rate expressions have been derived and explained in the light of experimental findings.
Shape‐memory pore structure in porous crosslinked polystyrenes
Authors: Takeda Kunihiko , Akiyama Minoru , Yamamizu Takafumi
Published: April 2003

Porosity of porous crosslinked polystyrenes was examined by the pressurized‐mercury intrusion method. Various aftertreatments of those polymers revealed interesting results of behaviors of “fixed pores”, whichS indicates pores measurable by this method: (1) fixed pores were found to diminish or vanish by swelling them with ethylene dichloride (EDC) as a good solvent or by heating them above the glass transition temperature (Tg), but (2) those pores were observed to reappear after the polymers treated above were swollen again with EDC, followed by replacing EDC with methanol as a poor solvent. This implies that the fixed‐pore structure has been memorized like a shape‐memory alloy.