bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemische charakterisierung von elektronen‐bestrahltem polypropylengranulat
Authors: Klee D. , Gribbin D. , Kirch D. 
Published: April 2003

AbstractIn jüngster Zeit wird der Einsatz von elektronen‐bestrahltem Polypropylengranulat als Nukleierungsmittel bei der Extrusion vorgeschlagen. Die vorliegende Arbeit beschäftigt sich mit der chemischen Charakterisierung der elektronen‐bestrahlten Granulate. Da die Bestrahlung unter atmosphärischen Bedingungen stattfindet, werden nicht nur der Zusammenhang von Abbau und Vernetzung, sondern auch Oxidationsprodukte bestimmt. Die oxidative Schädigung findet hauptsächlich in den oberen Moleküllagen statt und führt über peroxidische Zwischenprodukte zur Entstehung von Carbonylgruppen. Neben für funktionelle Gruppen spezifischen Nachweismethoden wird die oberflächen‐spezifische ESCA‐Methode zur Erfassung des Oxidationsgrades und zur indirekten Vinylgruppenbestimmung nach der Bromierung eingesetzt.
Emulsionspolymerisation von vinylchlorid, 10. Einfluß wasserlöuslicher oligomerer auf das dehydrochlorierungsverhalten des polymeren
Authors: Tauer Klaus , Behnisch Jürgen 
Published: April 2003

AbstractDie Dehydrochlorierung unterschiedlicher PVC‐Proben wird mit Hilfe eines Thermoanalyzers, der mit einer konduktometrischen Meßzelle gekoppelt ist, untersucht. Die Messungen erfolgen nichtisotherm. PVC‐Proben unterscheiden sich synthesebedingt in dem Gehalt an niedermolekularen wasserlöslichen Oligomeren. Mit steigender Konzentration der oligomeren Produkte in den Pulvern wird eine erhöhte HCl‐Abspaltung bei niedrigen Temperaturen gemessen. Die Bildung der Oligomeren in Abhängigkeit von der Polymerisationsrezeptur, dem Umsatz und der Monomerkonzentration wird diskutiert.
Modification of gelatin by grafting
Authors: George Anne , Radhakrishnan Ganga , Joseph K. Thomas 
Published: April 2003

AbstractGraft copolymerization of butyl acrylate onto gelatin has been carried out using potassium persulphate as initiator both in aqueous and in water‐acetic acid medium. Kinetic parameters like rate of grafting, percent grafting, and grafting efficiency were determined for the two systems. The grafting was proved by IR spectra of the isolated graft chains which showed amide absorption bands characteristic for the amino acids.
Acetylation behaviour of cotton and bagasse celluloses. III. Upgrading pulps by extraction with sodium hydroxide‐borax solutions
Authors: Abou‐State M. Amine , Helmy Samia A. , El‐Din Nabil M. Safy 
Published: April 2003

AbstractThe presence of borax during alkali refining of pulps increased the solubility of the short‐chain celluloses and hemicelluloses and thus improved their chemical characteristics. Small improvements in the chemical characteristics of cotton linters took place. A stronger effect was observed in case of the dissolving pulp and a more pronounced effect took place in case of the kraft pulp. Cold 20% NaOH refining was more effective than hot 5% NaOH refining. The physical and sub‐microscopic characteristics of linters were mainly affected. Refining lowered the D.P., increased the affinities towards water and alkali, decreased the crystallinity, and improved the reactivity towards xanthation. The presence of borax resulted in a more open and accessible fine structure and better reactivity. Cold refining of the dissolving and kraft pulps resulted in lower reactivity than hot refining and the presence of borax improved the reactivity. It also increased the yield of cellulose acetate. The increase in the solubility of the short‐chain celluloses and hemicelluloses resulting from the presence of borax resulted in better homogenisation of the pulp. This was reflected in better chemical and physical characteristics of the acetate.
Zum einfluß hochdispersen polyvinylchlorids auf die polymerisation aminhaltiger monomerer der acrylreihe
Authors: Eliseeva V. I. , Aslamazova T. R. , Morozova E. M. , Göurnitz E. , Wulf K. , Bischof C. 
Published: April 2003

AbstractDie radikalische Polymerisation von aminhaltigen Acrylmonomeren wird in Anwesenheit von PVC als Füllstoff beschleunigt. Zur Klärung des Effekts wird der Einfluß der PVC‐Konzentration auf die Polymerisationskinetik von Acrylmonomeren mit und ohne Aminogruppe bestimmt sowie durch viskosimetrische und Quellungsmessungen die Immobilisierung der Monomeren am Füllstoff untersucht. Die Ergebnisse bestätigen die Vorstellung von einer spezifischen chemischen Wechelwirkung zwischen PVC und aminhaltigem Monomeren.
Improving the dyeing properties of textiles via utilization of redox systems. II. Dyeing of nylon‐6 with acid dye
Authors: Ibrahim N. A. , Haggag K. , Hebeish A. 
Published: April 2003

AbstractRedox systems based on potassium, sodium or ammonium peroxodisulphate or potassium periodate as oxidant and glucose, thiourea, sodium thiosulphate or potassium pyrosulphite as reductant were incorporated in the dyeing bath of nylon‐6 under a variety of conditions. An acid dye, namely Kiton Scarlet 4 R was used. The colour strength and dye fixation enhanced outstandingly in presence of the redox system, depending upon kind and concentration of the redox components. Raising the dyeing temperature from 30 to 60°C caused significant improvement in colour strength. The same holds true for duration of dyeing up to 60 min. Beside association of the dye with nylon‐6 by salt‐like bond, a free radical mechanism was suggested.
Reactive polymers, 50. The use of porous polymers in the sorption of tricyclic antidepressant in vitro
Authors: Horák D. , S̆vec F. , Kálal J. 
Published: April 2003

AbstractThree types of chemically different macroporous copolymers were investigated with respect to the possibility of their application as potential drug sorbents in blood detoxication and compared with activated charcoal which is used for this purpose in most cases. The measurements with a model drug solution were carried out in a dynamic arrangement under conditions resembling haemoperfusion. The effect of particle size of the sorbent on the rate of sorption and actual capacity of the column was detected and elucidated.
The structure of blends of polyethylene and polypropylene with EPDM elastomer
Authors: Fortelný Ivan , Kovář Josef , Sikora Antonín , Hlavatá Drahomíra , Kruliš Zdeněk , Nováková Zuzana , Pelzbauer Zdeněk , Cbreve;efelín Pavel 
Published: April 2003

AbstractThe structure of polyethylene/ethylene‐propylene‐diene (PE/EPDM) and polypropylene/ethylene‐propylene‐diene (PP/EPDM) blends prepared in the whole concentration range of components by mixing in the melt was investigated. The dependence of the torque in mixing on the composition of the blend is more complicated than reported in the literature. The dependence of morphology on composition is similar for both types of blends. According to the X‐ray scattering measurement EPDM considerably reduces the crystallinity of both PE and PP in the blend.
Die modifikationsspezifische wirksamkeit von keimbildnern in polypropylen
Authors: Moos K.‐H. , Jungnickel B.‐J. 
Published: April 2003

AbstractEs wird über kristallisationskinetische Untersuchungen an isotaktischem Polypropylen berichtet, das mit dem Farbstoff γ‐Chinacridon in unterschiedlichen Konzentrationen versetzt wurde. Durch geeignete Wahl der Präparationsbedingungen konnten Proben mit vorgegebenem Massenverhältnis zwischen kristalliner α‐ und kristalliner β‐Modifikation hergestellt werden. Aus der Analyse des Kristallisations‐ und Schmelzverhaltens konnte, für beide Kristallmodifikationen getrennt, auf die Lamellenseiten‐ und ‐deckflächenenergien der Kristalle gegenüber der eigenen Schmelze sowie gegenüber dem zugesetzten Farbstoff geschlossen werden. Die Ergebnisse belegen, daß durch das γ‐Chinacridon bevorzugt die Bildung von β‐Kristallen gefördert wird; die Stabilität entsprechender Sekundärkeime bis weit über die Gleichgewichtsschmelztemperatur hinaus wird experimentell und theoretisch nachgewiesen.
Poly(oxyethylene) diglycolic acid: A novel blending antistatic agent for polyamide fibres
Authors: Zhao Yao M. , Kimura Yoshiharu , Taniguchi Isoji , Sano Yoshiyuki , Muraoka Youichiro 
Published: April 2003

AbstractPoly(oxyethylene) diglycolic acids (PEO acids) with average molecular weights of Mn = 8 400 (Ia), 3 300 (Ib), and 1 000 (Ic) were used as blending anti‐electrostatic agents for nylon 6 (Ny6) fibres. The blended fibres containing 2.0 and 5.0 wt.‐% of the PEO acids were successfully spun by the melt‐blend spinning process at 260°C. Processabilities of the spinning and the drawing of the as‐spun filaments were little deteriorated compared with those of the Ny6 control. During the spinning block condensation of I and Ny6 occurred by reaction of their mutual end‐groups. The block copolymers produced were distributed in the filament matrix as coarsely dispersed spheres to form sea‐island structures. These fibres showed good antistatic properties; their performances were in the order of Ia > Ib > Ic, which was parallel to the size, not the number, of the islands. The tensile properties of the fibres containing 2.0 wt.‐% of Ia and Ib were comparable with those of the control. The dyeabilities examined for their knits were not seriously affected, either. In addition, it was indicated that the performance of antistatic property was not lost at all after the dyeing and the subsequent repeated washings. This is because I is anchored covalently to the Ny6 fibre matrix by the condensation above.
Preparation and properties of dialysis membranes prepared from a ternary solution of cellulose acetate/acetone/dimethylformamide
Authors: Schauer J. , Pelzbauer Z. , Vacík J. 
Published: April 2003

AbstractDialysis membranes were prepared by casting a solution of cellulose acetate in a mixed solvent acetone/dimethylformamide (1:1) followed by partial evaporation of the solvent from the cast solution at room temperature and by coagulation in icewater. The effect of the polymer concentration in solution and evaporation time of the solvent on tensile strength, morphology, and permeability of the membranes was investigated. Membranes possessing the best mechanical properties are formed from solutions containing 20–28 wt.‐% cellulose acetate and at evaporation times longer than three minutes. The membranes contain the minimal amount of cavities in their lower layer. The permeability of the membranes for low molar mass compounds increases with decreasing polymer concentration in the casting solution and with extension of the evaporation time of the solvent up to ca. 2 min.
Morphologie und eigenschaften schlagzähmodifizierter teilkristalliner polymerer
Authors: Kloos Friedrich 
Published: April 2003

AbstractEs wurden Untersuchungen über die Zusammenhänge zwischen der Morphologie und den Eigenschaften von schlagzäh modifiziertem Polypropylen und Polyoxymethylen durchgeführt. Durch Bestimmung der Volumendilatation bei uniaxialer Deformation wird beim schlagzäh modifizierten Polypropylen ein Übergang von einem Scherfließprozeß zum Crazing festgestellt, wenn die Einfriertemperatur der amorphen Bereiche des Polypropylens unterschritten wird. Beim schlagzäh modifizierten Polyoxymethylen laufen beide Prozesse gleichzeitig ab, wobei das Scherfließen die Kinetik der Deformation festlegt. Durch Beeinflussung der Morphologie bei der Herstellung der Legierungen über Schmelzmischverfahren und über Blockcopolymerisationsverfahren kann ihr Einfluß auf die Deformationsvorgänge überprüft werden. Es ergeben sich ähnliche Gesetzmäßigkeiten, wie sie für amorphe schlagzähe Polymere gefunden werden.
Study on formation, morphology, and properties of Si3N4 and SiC fibers
Authors: Hanna S. B. , Abdel‐Mohsen F. F. 
Published: April 2003

AbstractSilicon nitride and silicon carbide fibers were prepared by firing silicon resin mixed with iron under NH3 flow at 1 500°C. The effect of preparation variables, iron content, flow rate of NH3 gas, and time of heating, on the yield and Si3N4/SiC ratio was studied. The yield of reaction increases considerably with increasing the iron content up to 1.7 wt.‐% iron and decreases slightly beyond this value. The Si3N4/SiC ratio in the yield is affected in the same direction. Heating for a longer time at 1 500°C favours the formation of silicon carbide instead of silicon nitride. The conversion reaction remains constant for the gas flow rates greater than 0.5 1/min.The product has grown dominately in the form of smooth and uniform fibers of a mean diameter of less than 0.3 μm. The electrical resistivity and hardness of silicon nitride and carbide composite material were measured and discussed on the basis of its composition.
Modification of polyethylene with methacrylic acid, III. Wide angle X‐ray scattering and small angle light scattering study of the modificates
Authors: Bryjak Marek , Trochimczuk Witold 
Published: April 2003

AbstractThe structures of membranes obtained from low‐density polyethylene (LDPE) grafted with methacrylic acid (MA) have been studied. Using WAXS and SALS methods it has been shown that introduction of up to 0.5 mol/dm3 of poly(methacrylic acid) (PMA) does not affect the initial structure of PE. It was concluded from SALS measurements that the PMA domains are located in the interspherulite regions of PE.
Synthesis, characterization, and thermal behaviour of new epoxy polyesterimides
Authors: Martínez Pedro‐Alberto , Cádiz Virginia , Mantecón Ana , Serra Angels 
Published: April 2003

AbstractNew epoxy resins have been synthesized by the reaction of diimide‐diacids trimellitimide derivatives containing different aliphatic and aromatic fragments in N‐methyl pyrrolidone (NMP) with their corresponding diglycidylesters, using several molar ratios. The polymer composition has been determinated by chemical and elemental analyses. Their IR, 1H, and 13C NMR spectral data allowed to confirm the structural unit. Epoxy polyesterimides are soluble in polar organic solvents and show good thermal resistance. Differences on the basis of the introduced aliphatic or aromatic fragments were observed.
A new class of photopolymers with pendent dimethylmaleimide groups. III. Comparative study of different photopolymers with pendent olefinic structures including dimethylmaleimide groups
Authors: Finter Jürgen , Haniotis Zeppos , Lohse Friedrich , Meier Kurt , Zweifel Hans 
Published: April 2003

AbstractA series of photopolymers with the same polymer backbone but with different pendent chromophors including four imidyl structural units — dimethylmaleimide, 4‐methyl‐3,4,5,6‐tetrahydrophthalic acid imide, 3,4,5,6‐tetrahydrophthalic acid imide, and 3,4‐dihydro‐1,2‐naphthalene dicarboxylic acid imide — as well as trans‐3‐phenyl propenoyl (cinnamoyl) and 1,3‐diphenyl‐2‐propenonyl (chalcone) units were synthesized by polymer analogous reaction of the corresponding carboxylic acid chloride derivatives with poly(vinyl alcohol). The polymers, sensitized with thioxanthone, were characterized by their minimal exposure energies derived from gel point as well as photographic sensitivity measurements. Quantitative relations between chromophore conversion and exposure were established for unsensitized films of the chalcone and the 3,4‐dihydro‐1,2‐naphthalene dicarboxylic acid imidyl polymer. Upon irradiation with monochromatic 365 nm light the sensitized and unsensitized imidyl polymers proved to be one order of magnitude more sensitive than the chalcone and cinnamoyl polymers.
Tensile deformation of regenerated and native cellulose fibres
Authors: Northolt M. G. , De Vries H. 
Published: April 2003

AbstractThe tensile deformation of well‐oriented cellulose fibres has been reexamined. It is demonstrated that not only the fibre structure but also the deformation mechanism is similar to that found in high performance aramid fibres. An explanation is proposed for the difference between the elastic moduli of cellulose I and II. In view of these results it is possible to assess the prospect for improving the mechanical properties of cellulose fibres.
Étude des propriétés rhéologiques des mélanges de polypropylène‐polystyrène et de polystyrène‐polyéthylène basse‐densité
Authors: Deri Fawaz , Genillon René , May J. F. 
Published: April 2003

AbstractLe but de ce travail est d'examiner les propriétés rhéologiques à l'état fondu des mélanges à base de PP/PS et LDPE/PS. Les mélanges ont été examinés dans le domaine des températures 160–210°C. Les courbes des variations de la viscosité apparente en fonction de la composition à tension et vitesse de cisaillement constante pour le PP/PS présentent un minimum, les courbes des variations du facteur de Barus en fonction de la composition passent par un maximum. Il semble que le domaine de faible viscosité est associé à un domaine de forte élasticité pour les matériaux viscoélastiques examinés.
Theoretical reactivity of tolylene‐2,4‐diisocyanate and tolylene‐2,6‐diisocyanate, and structures of oligomers contained in the products of conversion of tolylene‐2,4‐diisocyanate into urethane and biuret derivatives
Authors: Czerwiński Wojciech , Ciemniak Grażyna 
Published: April 2003

AbstractBy the methods of quantum chemistry it is possible to calculate a number of theoretical quantities dependant on the structure of chemical compounds. In this paper quantum chemical calculations have been done in order to explain quantitatively the differences in the reactivity of isocyanate groups in tolylene diisocyanates and for the account of directions of oligomer formation with definite structures. These quantities have been connected in a simple way with the chemical reactivity of the molecules. The results of calculations made with the INDO semiempirical method are in a very good correlation with results of experimental investigations.
Synthesis of poly(acrylic acid)‐and poly(styrene)‐cyanoethylated cotton graft copolymers using gamma radiation
Authors: Hebeish A. , Zahran A. H. , Rabie A. M. , El‐Naggar A. M. 
Published: April 2003

AbstractSix substrates, untreated cotton (substrate I), alkali‐treated cotton (substrate II), and cyanoethylated cottons having 0.12% N (substrate III), 0.55% N (substrate IV), 0.77% N (substrate V) and 1.24% N (substrate VI) were graft copolymerized with either acrylic acid or styrene at different monomer concentrations and radiation dosages. The effect of using water/methanol mixtures at different ratios as polymerization media for graft copolymerization of the six substrates with styrene on the graft yield was also investigated. Furthermore, moisture regain and dyeability of the six substrates before and after copolymerization were examined. It was found that the graft yield increases by increasing monomer concentration and radiation dose irrespective of the monomer or substrate used. Using water/methanol mixtures as polymerization media was advantageous for grafting of styrene onto the six substrates. Nevertheless, for a given set of polymerization conditions, the graft yield follows the order: substrate VI > substrate V > substrate IV > substrate III > substrate II > substrate I, indicating that presence of cyanoethyl groups in the molecular structure of cotton cellulose affords additional sites for graft polymerization. Poly(acrylic acid)‐cyanoethylated cotton graft copolymers show much higher moisture regain than cyanoethylated cottons particularly when the carboxylic groups of the graft were in the sodium form. The opposite holds true for poly(styrene)‐cyanoethylated cotton graft copolymers which exhibit much lower moisture regain as compared with cyanoethylated cottons. The colour strength of cyanoethylated cotton dyed with direct or reactive dyes decreases significantly after copolymerization with poly(acrylic acid) prior to dyeing. On the other hand, this copolymerization improves the affinity of cyanoethylated cottons for the basic dye and brings about perceptible shade. With respect to poly(styrene)‐cyanoethylated cotton graft copolymers, they acquire higher colour strength than the cyanoethylated cottons when dyed with direct, disperse, and basic dyes but lower colour strength upon dyeing with the reactive dye. Also reported were the moisture regain and dyeability of untreated and alkali‐treated cotton before and after copolymerization with acrylic acid or styrene for comparison.
Viscoelastic behaviour of molten polypropylene/polyethylene blends
Authors: Santamaría A. , Muñoz M. E. , Peña J. J. , Remiro P. 
Published: April 2003

AbstractSome aspects of the viscoelastic behaviour of 10 blends of polypropylene and long branched polyethylene have been studied. Shear viscosity measurements have been carried out at temperatures from 180 to 220°C and shear rates from 1 s−1 to 1 000 s−1. The elasticity has been studied in terms of the extrudate swell, entrance pressure losses, and shrinkage effects. The most striking results are the enormous shrinkage effects observed on the extrudates at 180°C: for some blend compositions the reduction of the initial length of the sample attains a value of 800%.
Systèmes réactifs polyuréthannes bloqués, 4. Cinétique de réaction en présence de tissus de renforcement. Propriétés des matrices correspondantes
Authors: Viollaz François , Lam Thanh My , Pascault Jean‐Pierre , Camberlin Yves 
Published: April 2003

AbstractDie Reaktion von geblockten Isocyanat‐Präpolymeren mit einem aliphatischen Diamin wurde in Gegenwart von faserverstärkenden Materialien (Carbonfasern und Glasfasern mit unterschiedlicher Oberflächenbehandlung) untersucht. Die Molekulargewichte der Polyurethanharnstoffe wurden durch Gelpermeationschromatographie als Funktion der Reaktionszeit gemessen. Niedrigere Molekulargewichte wurden in Gegenwart von Glasfasern erhalten, mit einem einschneidenden Abfall bei rohem Glas.Diese Ergebnisse können durch komplexierende Aminfunktionen auf der Faseroberfläche erklärt werden.
New block copolymers. 1. Synthesis and characterization of an (a–b)n type block copolymer
Authors: Mahato Beni Madhab , Shit Subhas Chandra , Maiti Mrinal M. , Maiti Sukumar 
Published: April 2003

AbstractA new (A–B)n type block copolymer has been synthesized by polycondensation of acidchloride terminated poly(ethylene‐terephthalate) with amine‐terminated butadiene acrylonitrile rubber (ATBN). The acid chloride terminated poly(ethylene‐terephthalate) was synthesized by reacting terephthaloyl chloride with ethylene glycol using N,N‐dimethyl formamide as the solvent. The resulting polymer was characterized by nitrogen analysis, IR and NMR spectroscopy. The solubility characteristics, solution viscosity behaviour, crystallinity, and phase characteristics of the polymer have been studied.
The dielectric behaviour of shellac‐urea‐formaldehyde resins
Authors: Goswami D. N. 
Published: April 2003

AbstractThe Cole‐Cole method has been employed for an analysis of the dielectric relaxation data, obtained by Bhattacharya, of a shellac‐urea‐formaldehyde resin (SUF) in the temperature range 30–100°C. Three relaxation processes were observed for temperatures 30 to 50°C. At 60°C, two relaxation processes were noticed. The relaxations at 70°C and above represented typical Cole‐Cole type. The static dielectric constant, relaxation time and distribution parameter of SUF were found to be greater than those of the unmodified shellac. Marked changes in the above mentioned parameters were observed during a rise of temperature from 70 to 100°C. The results of the present study indicate that some rearrangement in the tertiary disposition of the resin molecules takes place during the rise of temperature from 30 to 100°C.
Re‐analysis of extensional flow data of polymer melts
Authors: Shenoy A. V. , Saini D. R. 
Published: April 2003

AbstractExtensional flow behaviour is very important in polymer processing operations such as fiber spinning and film blowing but there is scanty experimental data in the literature due to inherent difficulties in measurement of the relevant flow parameters. In the present paper, an attempt has been made to correlate the existing available data on the extensional flow of three generic types of polymer melts through a logarithmic plot of modified extensional viscosity function, ηE · MFI, and a modified extension rate, (ε/MFI)2. The method may be extended to other polymeric systems.