bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rheological properties of poly‐α‐olefin melts
Authors: Shirayama Kenzo , Matsuda Tadashi , Kita Shin‐Ichiro 
Published: April 2003

AbstractIn order to investigate the influence of the side‐chain‐length on the melt viscoelasticity of the hydrocarbon polymers, dynamic viscosity η′, dynamic rigidity G′ and apparent viscosity ηa of a series of six different poly‐α‐olefins have been measured with a rotating cylinder‐type rheometer.The molecular weight dependence of η′ and ηa was relatively greater at lower shear rate. At fixed shear rate and temperature, η′, G′, and ηa for each polymer sample were expressed by the form of KM. The values of K decreased with increasing side‐chain length and the values of α were approximately 3–4 for all the samples studied.η′ vs. ω G′ vs. ω and ηa vs. γ curves at different temp. (130–230°C) could be superposed according to the usual time‐temperature superposition method, and the shift factors aT obtained from η′, G′, and ηa were practically the same.The flow activation energies obtained from aT first increased with increasing side‐chain length in going from polyethylene to polyhexene‐1, and thereafter decreased in going from polyhexene‐1 to polyoctadecene‐1. They were all lower than that of high pressure polyethylene.These results appear to support the idea that the branching structure of high pressure polyethylene is much more complicated than the side‐chain structure of poly‐α‐olefins.
Über die aktivität von katalysatorgemischen aus metallorganischen verbindungen und thalliumtrichlorid bei der trioxanpolymerisation
Authors: Glavčev I. , Kabaivanov V. , Natov M. , Šperov I. 
Published: April 2003

AbstractDie Untersuchung der katalytischen Aktivität von Gemischen aus unterschiedlichen metallorganischen Verbindungen und Thalliumchlorid bei der Trioxanpolymerisation ergab, daß sie vom Ionencharakter bzw. von der Art der metallorganischen Verbindung abhängig ist. Die aktivsten Katalysatorgemische bilden sich aus Thalliumchlorid und organischen Verbindungen von Magnesium und Aluminium mit 22–34% Ionencharakter. Beim Vermengen von Thalliumtrichlorid mit metallorganischen Verbindungen bilden sich Komplexe mit dem unbeständigen Tl3⊕, deren Konzentration zeitlich abnimmt. Am schnellsten vollzieht sich die Konzentrationsabnahme von Tl3⊕ in den katalytisch aktivsten Gemischen. Untersucht wurde ferner der Einfluß des Wassergehalts im Monomeren auf den Polymerisationsvorgang.
The polymerisation of propylene oxide by organomagnesium compounds
Authors: Stafford J. W. 
Published: April 2003

AbstractDiethyl magnesium as a diethyl etherate‐dioxanate complex polymerises propylene oxide in a diethyl ether solution to very high molecular weight crystalline polymer. Magnesium dibromide diethyl etherate polymerises propylene oxide in diethyl ether to low polymer. Ethyl magnesium bromide diethyl etherate polymerises propylene oxide in diethyl ether in four distinct kinetic stages. In the first two kinetic stages, polymer similar to that produced by diethyl magnesium is obtained in very low yield. Polymer of Mv ≈ 10,000 to 15,000 in yields up to 50% is produced in the next two stages. Above a certain catalyst concentration, the second stage is characterised by gel formation and precipitation. The third kinetic stage, during which most of the eventual polymer yield is produced, occurs with breakdown of the gel and redissolution of the precipitate, a similarity with polymerisation of propylene oxide by magnesium dibromide. With the ethyl magnesium bromide polymerisation, above the aforementioned catalyst concentration, change of catalyst concentration or solvent affects only the initial polymerisation stage kinetically.
Synthese und chemische Eigenschaften einiger Copolymerisate von 8‐Hydroxy‐5‐vinyl‐chinolin‐Derivaten. 2. Teil: Amphotere Kationenaustauscher
Authors: Manecke Georg , Aurich Hans‐Peter 
Published: April 2003

Abstract5‐Vinyl‐8‐benzyloxy‐chinolin bzw. ‐chinaldin wurden mit Divinylbenzol copolymerisiert. Die vernetzten Produkte wurden mit verdünnter Salzsäure entbenzyliert. Durch polymeranaloge Bromierung wurde ein Teil der Harze modifiziert. Die Aufnahmefähigkeit der Harze für Cu2⊕‐, Ni2⊕‐ und Zn2⊕‐Ionen wurde untersucht, und die hohe Austauschkapazität für diese Ionen wird diskutiert.
L'isocaoutchouc. Etude des paramètres de cyclisation et d'isomérisation
Authors: Pinazzi C. P. , Brossas J. , Clouet G. 
Published: April 2003

AbstractCette étude présente une nouvelle préparation du méthylènecyclobutane qui permet d'obtenir avec une grande pureté ce monomère. La polymérisation du méthylènecyclobutane suivant un processus de Ziegler‐Natta ternaire y est étudiée en détail, ce qui a permis de mettre en évidence que le polymère à double liaison exo passait par le stade endo avant de se cycliser. Enfin, nous avons commencé une modification chimique de l'isocaoutchouc et notamment une ozonisation qui a donné une polycétone linéaire.
Influence of the stereoselectivity of the polymerization process on the optical activity of isotactic copolymers of enantiomeric α‐olefines
Authors: Bonsignori Osvaldo , Luisi Pier Luigi , Suter Ulrich 
Published: April 2003

AbstractThe molar optical activity [Φ]D of isotactic copolymers of enantiomeric α‐olefins as a function of the monomer optical purity P has been calculated for a particular kinetic model of stereoselectivity. According to this model, the catalyst is considered a racemic mixture of dissymmetric enantiomeric catalytic centers, able to discriminate between the two enantiomeric comonomers.The calculations have been performed for copolymers of (S)‐ and (R)‐4‐methyl‐1‐hexene and of (S)‐ and (R)‐3.4‐dimethyl‐1‐pentene. The stereoselectivity has been related to the auxiliary parameter c, defined as the ratio between the two rate constants which determine the insertion of (R) and (S) monomers to the catalytic centers. The patterns of [Φ]D versus P calculated for different c values are rather close one to the other in the region of low stereoselectivity (c > 0.6). These results confirm that optical activity is not very sensitive to the features of the stereoselectivity of the copolymerization process. It is pointed out, however, that more useful information could be obtained from the study of the temperature coefficient of optical activity, particularly if more suitable polymeric structures are chosen.
Physical properties of poly‐1‐methyloctamer, a model of the ethylene/propylene copolymer
Authors: Gianotti G. , Dall'asta G. , Valvassori A. , Zamboni V. 
Published: April 2003

AbstractInvestigation of ethylene/propylene random copolymers of constant overall composition has shown that some physical properties strongly depend on the intramolecular distribution of the monomeric units. In order to elucidate the relationships between monomer distribution and properties, a copolymer model was prepared by ring‐opening homopolymerization of 3‐methylcyclooctene and successive hydrogenation of the double bonds. Its structure
magnified image
may be considered as that of a copolymer in which one propylene and three ethylene units regularly alternate. Some physical, in particular thermodynamic properties of the model compound were investigated and compared with those of a random copolymer of the same overall composition.
Hydrodynamic properties and unperturbed dimensions of poly‐4‐chlorophenylmethacrylate in various solvents
Authors: Tricot M. , Desreux V. 
Published: April 2003

AbstractEight fractions of poly‐4‐chlorophenylmethacrylate prepared by radical polymerization have been studied by viscosity in various solvents, by sedimentation, osmotic pressure and light‐scattering in benzene.The average unperturbed dimension was obtained in different ways with a good agreement, although the molecular weight range is large. The results as compared with those given for other polymethacrylic esters of the same type show that the effect of a para‐substitution in the phenyl group has little effect on the flexibility of the chain.
Studies in addition polymerization in mixed solvent system part V. Chain transfer of short chain aliphatic alcohols in the polymerization of methyl methacrylate and styrene
Authors: Bhattacharyya Bhupati Ranjan , Nandi Uma Shankar 
Published: April 2003

AbstractStudies on Polymerization in the presence of alcohols has been carried out using mixed solvent system. It is observed that chain transferring capacity of the aliphatic alcohols do increase with the size of the alkyl group, the order being methyl alcohol < ethyl alcohol < n‐propyl alcohol < iso‐propyl alcohol. The results indicate that α‐hydrogen abstraction from the substrate is effective. The chain transfer constants obtained from the conventional plot of 1/P̄ against S/M is in fair agreement with the values computed from the estimation of hydroxyl end group in the polymer by dye‐partition technique. The increasing transfer constant values in the alochol series with increase in the number of carbon atoms is explained on the basis of probability of available hydrogen atom in the alkyl group. It is also observed that the chain transfer values are affected due to precipitation of polymer. Thermodynamic parameters have been computed from the chain transfer values of alcohols at different temperatures.
Carbon‐13 nuclear magnetic resonance spectroscopy of polypropylene
Authors: Inoue Yoshio , Nishioka Atsuo , Chûjô Riichirô 
Published: April 2003

AbstractThe proton decoupled natural abundance 13C (designated as 13C‐{1H}) high resolution nuclear magnetic resonance spectra were measured for polypropylene at 25.1 MHz. The samples used were 4 polymers of different tacticity. The spectra of methylene carbon split corresponding to diad and partially tetrad placements. The spectra of methyl carbon of stereoblock type polymer clearly split corresponding to pentad placements. These splittings were tentatively assigned. The relation between the relative intensities of pentad placements, namely,

was not satisfied. As the causes of this inequality, several possibilities were pointed out.The triad microtacticity of highly isotactic polymers determined from 13C‐{1H} spectra were compared with the results of n‐heptane extraction and good correspondence within experimental error were obtained. The discrimination of configurational sequences of polypropylene by 13C‐{1H} spectra at 25.1 MHz is equal or superior to that possible in 1H spectra at 220 MHz. However, the two peaks assigned to methine carbon showed abnormal intensities.
Reaction products of diphenyl sulfide with formaldehyde. Formaldehyde resins. 98
Authors: Kunieda Norio , Suzuki Akira , Kinoshita Masayoshi , Imoto Minoru 
Published: April 2003

AbstractThe acid‐catalyzed condensation of formaldehyde and diphenyl sulfide was carried out in benzene in the presence of p‐toluene sulfonic acid. From the products, four poly(methylene diphenyl sulfides) of the following structures were isolated.
magnified image
Synthesis and thermal characterization of cross‐linked Ti, Zr and Hf polyesters from poly(acrylic acid)
Authors: Carraher Charles E. , Piersma John D. 
Published: April 2003

AbstractThe synthesis of cross‐linked polyesters from the condensation of poly(acrylic acid) with Group IV B dicyclopentadiene dichlorides via the interfacial and solution techniques is described. The polyesters are believed to contain the following repeating units:
magnified image
Thermal properties of the polyesters were studied by Differential Scanning Calorimetry and Thermal Gravimetric Analysis.
Evaluation of the hydrocarbon condensation polymerisation reaction by means of model compounds. I. The reaction with n‐alkyl‐bromides
Authors: Davis A. , Richards D. H. , Scilly N. F. 
Published: April 2003

AbstractThe title polymerisation involves the reaction in tetrahydrofuran of α‐methylstyrene (M) with lithium in the presence of an alkyl dihalide (RX2) to form copolymers. This paper describes a method of studying the effect of changing the experimental parameters on the structure of these copolymers by replacing the dihalide with the corresponding monohalide (HRX). The study is confined to n‐alkyl bromides and the relative amounts of the molecules HR–RH and HRMnRH (where n = 1, 2, and 3) have been determined by g.l.c. By this means it is shown that the reaction is diffusion controlled and the rate proportional to lithium surface area. At 1 : 1 monomer : monohalide stoichiometry (equivalent to 2 : 1 monomer : dihalide in the polymer system) the product is ∼ 90% HRM2RH indicating that the copolymer under these conditions is highly regular with the repeat unit [M–M–R] predominating. The system is extremely sensitive to the reactant ratio and small deviations from stoichiometry result in significant reductions in dimer yield.
Evaluation of the hydrocarbon condensation polymerisation reaction by means of model compounds. II. The reaction of with n‐alkyl chlorides and iodides, and sec‐ and tert‐alkyl bromides
Authors: Davis A. , Richards D. H. , Scilly N. F. 
Published: April 2003

AbstractThe title polymerisation involves the reaction in tetrahydrofuran of α‐methylstyrene (M) with lithium in the presence of an alkyl dihalide (RX2) to form copolymers. Replacement of the dihalide by the analogous monohalide RX gives small molecules, the relative amounts of which furnish information on the polymerisation process and the resulting structures of the copolymers. This paper describes the use of n‐alkyl iodides and chlorides, and sec‐ and tert‐bromides in this regard.n‐Alkyl iodides were found to behave in a similar manner to n‐alkyl bromides (Part I) with high yields of the dimer HRM2RH being obtained at 1 : 1 M stoichiometry. On the other hand, n‐alkyl chlorides gave a variety of additional products under these conditions and a structural analysis of these materials showed that they resulted from reactions involving n‐alkyl lithium which was formed by the chloride reacting directly with the lithium. This difference in behaviour is explained in terms of the high strength of the carbon‐chlorine bond and implies that copolymers prepared with dichlorides are less regular than those obtained with dibromides.sec‐ and tert‐bromides also gave a variety of products at equimolar stoichiometry and this was shown to be due to the β‐hydrogen elimination reaction becoming significant. Elimination was most prominent with the tert‐bromides, accounting for about 60% of der termination reaction of the dimer.
Polymerization of methyl methacrylate in the presence of ferric nitrate
Authors: Narita Hiroshi , Sakamoto Yoshiaki , Machida Seishi 
Published: April 2003

AbstractThe polymerization of methyl methacrylate in the presence of ferric nitrate was studied. In spite of the conventional concept that the ferric salt is an inhibitor, the rate of polymerization was found to increase with increasing concentration of ferric nitrate in the range below 1.0·10−3 mole·1−1, and is represented by

An interaction between methyl methacrylate and ferric salt was detected by means of visible and infrared absorption spectra. As the effect of ferric salt shows up in the CO band rather than CC band, the ferric salt is considered to coordinate to the oxygen of the carbonyl group of methyl methacrylate to form a complex. The polymerization reaction proceeds via a radical mechanism, and probably is initiated by the decomposition of the complex. On the copolymerization of methyl methacrylate with styrene and methacrylamide, no effect of ferric salt is observed with respect to the compositions of the resulting copolymers. It is considered that the ferric salt initiates the polymerization only within a range of its lower concentrations. At higher concentrations, the ferric salt terminates the polymerization.
The development of a cryoscopic apparatus
Authors: Stepto R. F. T. , Waywell D. R. 
Published: April 2003

AbstractThe development and use of a cryoscopic apparatus are described. Temperatures are simply measured by means of a thermistor and WHEATSTONE bridge. However, the thermal conditions within the cryoscopic cell during freezing were closely controlled with the result that a quick and accurate method for determining a series of freezing points without supercooling was made possible. The apparatus and method have been tested using solutes of molecular weights up to 2000.
Radical terpolymerization of vinyl sulfide, vinyl ether, and maleic anhydride. Evaluation of the reactivities of vinyl sulfide and vinyl ether alternative copolymerization. IV
Authors: Inoue Hiroshi , Otsu Takayuki 
Published: April 2003

AbstractThe terpolymerizations of maleic anhydride (MAn), vinyl sulfide (VS) and vinyl ether (VE) initiated by α.α′‐azobisisobutyronitrile were investigated in order to evaluate the reactivities of VS and VE toward poly(MAn) radical. Since both VS and VE undergo alternative copolymerization with MAn, these terpolymerizations were approximately treated on the basis of the free propagation and complex propagation mechanisms. From the treatment of the free propagation mechanism in which only three free monomers can participate, the reactivity of the free VS toward attack of the poly(MAn) radical was found to be 4.24 to 6.63 times higher than that of free VE, and the difference in activation energy was 1.5 kcal/mole. The higher reactivity of VS than VE might be explained by the 3 d orbital resonance between the propagating radical and the adjacent sulfur atom in VS. According to the complex propagation mechanism in which only two complexed monomers can participate, the reactivity ratios of the MAn/VS and MAn/VE complex monomers were also determined. It was found that the former complex was more reactive than the latter complex toward the poly(MAn) radical.
Fließverhalten und molekulare struktur von polymeren und ihren lösungen eine systematik quantitativer beziehungen
Authors: Hoffmann M. 
Published: April 2003

AbstractViskositäten bei kleinen und hohen Schubspannungen, kritische Schubspannungen der Strukturviskosität, Gummimoduli verhakter Polymerer, Konzentrationen beginnender Verhakung und Grenzviskositätszahlen hängen von Strukturparametern in quantitativer (Molekulargewicht, Uneinheitlichkeit, Konzentration, chemische Natur bzw. Kettendicke) oder in bisher erst qualitativ erkannter Weise (verschiedene Verzweigung, chemische Uneinheitlichkeit, Sequenzstruktur, Phasentrennung und Kristallisation) ab.Mehrere neue Gesetze werden mitgeteilt. Alle Beziehungen sind stärker untereinander verknüpft als bisher angenommen wurde und liefern einige phänomenologisch vergeblich gesuchte Gesetze für das Verhalten von Mischungen und Lösungen.
Synthese, thermostabilität und elektrische eigenschaften von tiefgefärbten polymeren mit anellierten phthalocyaninartigen systemen
Authors: Wöhrle Dieter , Kossmehl Gerhard , Manecke Georg 
Published: April 2003

Abstract2.5‐Diamino‐3.4‐dicyanthiophen wurde mit Terephthalsäuredichlorid zu einem Polyamid und mit Thiophen‐2.5‐dicarbaldehyd zu einem Polyazomethin umgesetzt. An beide Polymere konnte durch Reaktion mit Phthalodinitril und Kupferacetylacetonat ein phthalocyaninartiges System anelliert werden. Durch diese Anellierung wurde die thermische Stabilität der Polymeren gesteigert. Die elektrische Leitfähigkeit der beschriebenen Polymeren wurde mit einer neuen Meßzelle gemessen, die die Messung in jeder beliebigen Atmosphäre oder im Vakuum bei Drücken bis zu 5000 kp · cm−2 und bei Temperaturen bis zu 150°C gestattet.
Crystal structure of oligourethane. III. Crystal structure of acetoxy(pentamethyleneurethane) dimer
Authors: Tagawa Hiroyuki , Wada Eiichi , Sakurai Tosio 
Published: April 2003

AbstractThe crystal structure of acetoxy(pentamethyleneurethane) dimer,

was studied by the X‐ray diffraction method. The crystal is triclinic with

The diffraction patterns clearly show the existence of a subcell which is also triclinic with two (CH2)2 units in the unitcell. The subcell structure was determined by use of special non space group extinctions. The proposed crystal structure is that each of the two molecular chains in the main unit cell is connected side by side with other chains in the neighbouring cells by two hydrogen bonds to form molecular sheets parallel to the bs cs plane.
Condensation polymerization of nucleotide analogues
Authors: Seita Toru , Yamauchi Kiyoshi , Kinoshita Masayoshi , Imoto Minoru 
Published: April 2003

Abstract3‐(9‐Adenyl)‐, 3‐(3‐adenyl)‐, 3‐(9‐hypoxanthyl)‐ and 3‐(3‐hypoxanthyl)‐2‐hydroxypropyl dihydrogenphosphates were condensed in the presence of a large excess of N.N′‐dicyclohexylcarbodiimide (DCC). The major part of the oligomeric products is soluble in water and has a molecular weight of more than 1000 according to gel‐filtration measurement. The absorption spectra show 3% of hypochromism for mixtures of the oligo‐3‐(9‐adenyl)‐2‐hydroxypropyl phosphate with denaturated yeast RNA or sperm DNA.
Ionic polymerization of cyclic ethers. II. Bulk polymerization of β‐methylglycidaldehyde in the presence of aluminum isopropoxide as a catalyst
Authors: Jedliński Zbigniew , Majnusz Jerzy 
Published: April 2003

AbstractIn the course of further investigations of ring‐opening polymerizations we have studied the bulk polymerization of β‐methylglycidaldehyde (βMG) by aluminum isopropoxide at 20 and 50°C.The polymerization proceeds in two distinct stages. In the first stage the α.β‐epoxybutyl ester of α.β‐epoxybutyric acid (2.3‐epoxy‐n‐butyl‐1′.2′ ‐epoxybutyrate) (DßMG) is formed by a TISHCHENKO‐CLAISEN reaction.In the second stage this ester gives a polyether (PßMG) by polymerization of the epoxy groups adjacent to the ester carbonyl. The pendent epoxy‐butyl groups are attached to the polyether by an ester linkage. Mechanisms are proposed for the formation of dimer and polymer.
Kinetik der radikalischen copolymerisation α‐substituierter styrole mit styrol. 1. Teil. Copolymerisation von α‐methylstyrol mit styrol oberhalb der ceiling‐temperatur von α‐methylstyrol
Authors: Fischer J. P. 
Published: April 2003

AbstractDie radikalische Copolymerisation von α‐Methylstyrol mit Styrol läßt sich im Temperaturbereich von 60–150°C nach Gleichungen beschreiben, die WITTMER unter der Annahme abgeleitet hat, daß die Additionsreaktionen von α‐Methylstyrol reversibel sein können.Hierbei genügt es, im Temperaturbereich von 60–110°C lediglich die Reversibilität von α‐Methylstyrol‐Additionsschritten an ein Kettenende mit α‐Methylstyrol als letzter Monomereinheit zu berücksichtigen. Für 150°C als Reaktionstemperatur ergibt sich, daß auch die Addition von α‐Methylstyrol an ein Styryl‐Kettenende meßbar reversibel ist, jedoch mit einer Gleichgewichtskonstante, die um einen Faktor 30 unter der für die α‐Methylstyrol‐Homopolymerisation liegt.Aus der Retardierung der Styrolpolymerisation durch geringe Zusätze von α‐Methylstyrol werden die einzelnen Geschwindigkeitskonstanten und Aktivierungsenergien des Kettenwachstums und der Depolymerisation abgeschätzt.
Long chain branching and solution properties of low density polyethylene
Authors: Hama Tomohiko , Yamaguchi Kinya , Suzuki Tadao 
Published: April 2003

AbstractThe intrinsic viscosity, osmotic pressure and light scattering of solutions of fractionated samples of low density polyethylene (LDPE) were measured to study its long chain branching. The following relation was obtained between the two branching indices:

gη is the ratio of the intrinsic viscosities of the branched and linear polymers with the same molecular weight, and gs is the corresponding ratio of the radii of gyration. The average number of long branches per molecule, nw, was calculated according to the theory of ZIMM and STOCKMAYER derived for random branching, and it was found that the dependence of nw on the molecular weight is expressed by

with α = 0.85.This relation indicates that the long branching frequency or density decreases gradually with molecular weight for LDPE.