bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radical reactions initiated by chelate complexes of transition metals. II. Radical polymerization of styrene
Authors: Bartoň J. , Lazár M. 
Published: April 2003

AbstractBis‐(–)ephedrine copper(II) chelate initiates styrene polymerization in the presence of halogen compounds. Among the halogen compounds examined, the highest rate of Polymerization was found in the system bis‐(–)ephedrine copper(II) chelate‐carbon tetrachloride. The polymerization rate for constant carbon tetrachloride concentration can be described by the equation Rp = k [chelate]n with the exponent n = 0.26. For molar ratios of chelate over carbon tetrachloride equal to, or smaller than one, the rate of polymerization is practically independent of carbon tetrachloride concentration. In the case that [CCl4] < [Chelate] the dependence of the polymerization rate of the concentration of carbon tetrachloride can be expressed by the equation Rp = k[CCl4]n where n = 0.30. While bis‐(–)‐ephedrine copper(II) chelate acts as a retarder in styrene polymerization initiated with 2.2′‐azobisisobutyronitrile, it has a rate increasing effect in the dibenzoylperoxide initiated polymerization. In the first case the decrease of polymerization rate was attributed to the reaction of radicals with the chelate, while this is outdone by the catalytic effect of bis‐(–)ephedrine copper(II) chelate on benzoylperoxide decomposition in the second case.
Radical reactions initiated by chelate complexes of transition metals. III. Grafting of polymers containing halogen atoms
Authors: Bartoň J. , Lazár M. , Nemček J. , Maňásek Z. 
Published: April 2003

AbstractPolymerization of styrene is initiated by bis‐(–)ephedrine copper(II) chelate in presence of halopolymers and telomers containing terminal halogen atoms. The rate of polymerization at constant concentration of the chelate depends on the specific halopolymer used and its concentration i.e. on the concentration of halogen atoms in the polymerization system. It is suggested that initiation results from interaction of the chelate with the halogen atoms of the halopolymer leading to formation of reactive centres at the halopolymer. These centres are able to give rise to formation of graft and block copolymers in presence of suitable vinyl monomers.
Effects of aminoalcohol and alkoxyalcohol on the n‐butyllithium‐initiated polymerization of methyl methacrylate
Authors: Maruhashi Motokazu , Takida Hiroshi 
Published: April 2003

AbstractThe effects of the addition of aminoalcohols or alkoxyalcohols on the n‐butyllithium initiated polymerization of methyl methacrylate in toluene were studied. Stereoregulating behavior in the polymerization was affected remarkably by these additives. The addition of 2‐diethylaminoethanol, 2‐ethoxyethanol or tetrahydrofurfurylalcohol favored formation of syndiotactic type polymer in the polymerization at −78°C. On the other hand, isotactic type polymer was obtained by the addition of 3‐diethylainino‐1‐propanol or 1‐diethylamino‐2‐propanol.The influences of polymerization temperature and solvent were also investigated. In the polymerization with n‐butyllithium‐tetrahydrofurfurylalcohol system, these varibles affected scarcely on the stereoregularity of polymers, and considerably syndiotactic‐rich polymer was prepared even at 0°C, both in toluene and in tetrahydrofuran.It is confirmed by gas‐chromatographic analysis, electronic spectra, and the results of polymerization that the catalyst system consists of n‐butyllithium and lithium alkoxide of aminoalcohols or of alkoxyalcohols.
The solution properties of poly‐o‐chlorostyrene
Authors: Matsumura Kimiyoshi 
Published: April 2003

AbstractThe solution properties of poly‐o‐chlorostyrene in toluene were measured by means of light‐scattering and viscosity method, and the results were compared with those obtained from other polystyrene derivatives.The dependence of the intrinsic viscosity, the second virial coefficient and the end‐to‐end distance of the polymer chain on the molecular weight is follows:

These relationships do not differ substantially from those of other polystyrene derivatives.The unperturbed dimension of poly‐o‐chlorostyrene was calculated. Results showed that the polymer chain of poly‐o‐chlorostyrene at the theta state, {<L2>o/<L2>f}1/2 = 2.42, was more extended than that of poly‐p‐chlorostyrene, {<L2>o/<L2>f}1/2 = 2.15 to 2.30.
Vinyl compounds of nucleic acid bases. III. Polymerization and copolymerization of N‐vinyl and β‐methacryloyloxyethyl compounds of nucleic acid bases and their polymer‐polymer interactions
Authors: Kondo Koichi , Iwasaki Hiroshi , Nakatani Koichi , Ueda Nasuo , Takemoto Kiichi , Imoto Minoru 
Published: April 2003

Abstract9‐Vinyladenine, 1‐vinyluracil, 1‐vinylthymine, and β‐methacryloyloxyethyl derivatives of uracil, thymine and adenine were polymerized and copolymerized with acrylamide, maleic anhydride, and vinylpyrrolidone in different solvents. The polymer‐polymer interactions were measured by a spectrophotometric method. Poly(9‐vinyladenine) gave a hypochromic effect with ribonucleic acid in aqueous solution.
Investigations of the structure of ethylene‐propylene and ethylene‐butene copolymer crystals using fuming nitric acid. Part I. The molecular weight distribution of degraded copolymer crystals
Authors: Holdsworth P. J. , Keller A. , Ward I. M. , Williams T. 
Published: April 2003

AbstractThe effect of fuming nitric acid on single crystals of random ethylene‐propylene and ethylene‐butene copolymers has been investigated. In this paper changes in the molecular weight distributions which occur when such copolymer crystals are treated with fuming nitric acid will be described. The changes were examined using Gel Permeation Chromatography. It is shown that in all cases the changes in molecular weight distribution are similar to those observed when crystals of linear polyethylene are treated correspondingly. It is concluded that the copolymer crystals have a chain folded structure very similar to that of single crystals of linear polyethylene.A qualitative correlation between the changes in molecular weight distribution and changes in the melting behaviour of degraded polymer crystals will also be described.
Investigations of the structure of ethylene‐propylene and ethylene‐butene copolymer crystals using fuming nitric acid. Part III. The effects of nitric acid on the physical properties of single crystal mats of ethylene copolymers
Authors: Holdsworth P. J. , Keller A. 
Published: April 2003

AbstractThe structure of crystals of random ethylene‐propylene and ethylene‐butene copolymers has been investigated using fuming nitric acid. This paper is concerned with the effect of nitric acid on crystals grown from a series of copolymers. The weight losses and changes in long period, heats of fusion and unit cell spacings which result from acid treatment are reported. From these results and using the results reported in the earlier papers of this series it is concluded that crystals grown from both ethylene‐propylene and ethylene‐butene copolymers are very similar in structure to linear polyethylene single crystals apart from the fact that branches are contained within the crystalline cores of the copolymer crystals. It is shown that there are some differences between the way that ethylene‐butene and ethylenepropylene crystals are attacked by nitric acid, and a possible reason for this is suggested.
Kinetics and mechanism of the alkali‐catalysed condensations of di‐ and tri‐ methylol phenols by themselves and with phenol
Authors: Francis D. Joseph , Yeddanapalli L. M. 
Published: April 2003

AbstractThe kinetics of the alkali‐catalysed condensations of 2.4‐ and 2.6‐dimethylol phenol and 2.4.6‐trimethylol phenol by themselves and with phenol has been studied under various experimental conditions. The observed higher rates of self‐condensation of the methylol phenols have been explained on the basis of the relative reactivities of ortho and para methylol groups and the reactivities of the free nuclear positions in methylol phenols and phenol. A mechanism of the condensation reactions is also proposed.
Metal‐containing initiator systems. XII. Vinyl polymerization by pentacyanobenzylcobaltate(III) and by the binary systems of pentacyanocobaltate(II) and organic halides
Authors: Aoki Shuzo , Shirafuji Chiaki , Otsu Takayuki 
Published: April 2003

AbstractPentacyanobenzylcobaltate(III) acts as an effective initiator for the polymerization of methyl methacrylate (MMA), styrene, acrylonitrile, and vinyl acetate, and the initiating radical is assumed to be the benzyl radical produced from homolysis of the Carbon‐cobalt bond. The binary systems of pentacyanocobaltate(II) and some organic halides were also found to serve as initiators for the MMA polymerization. The initiating activity of these systems increased with decreasing dissociation energy of the carbon‐halogen bond in the halides. The polymerization of MMA and styrene by pentacyanobenzylcobaltate(III) was accelerated in the presence of benzyl bromide.
Permeability of solutes through hydrated polymer membranes. Part III. Theoretical background for the selectivity of dialysis membranes
Authors: Yasuda H. , Peterlin A. , Colton C. K. , Smith K. A. , Merrill E. W. 
Published: April 2003

AbstractThe diffusional transport of aqueous solutes through water swollen polymer membranes is examined by the concept of the free volume of the water‐polymer systems, Vf,13. The relative diffusivity (D in membrane/D in water) can be expressed by the product of the probability factor of finding holes of equal or larger cross section, q, than the cross section of solute, q2, (sieve mechanism) and the free volume factor. An analysis of experimental data indicates that within the range of solute size investigated (up to albumin) the sieve mechanism is not yet playing a role in homogeneous cellulosic membranes. The main reduction of permeability of larger solutes is caused by the free volume term which is an exponential function of the negative cross section of the solute, q2, exp (–Bq2/Vf,13). In porous membranes, however, the sieve mechanism alone is responsible for the selectivity.
Alternating copolymerization of phthalic anhydride and propylene oxide by dialkylzinc
Authors: Inoue Shohei , Kitamura Kazuyuki , Tsuruta Teiji 
Published: April 2003

AbstractThe mechanism of alternating copolymerization of propylene oxide with phthalic anhydride catalyzed by dialkylzinc is discussed. Dialkylzinc and phthalic anhydride form a complex which exhibits reactivity with propylene oxide to form alkylzinc alkoxide. Alkylzinc alkoxide thus formed reacts preferentially with phthalic anhydride in the presence of propylene oxide, giving alkylzinc carboxylate. Alkylzinc carboxylate then reacts selectively with propylene oxide to reproduce alkylzinc alkoxide. Repetition of these two reaction steps results in the formation of highly alternating polyester‐copolymer.
Bis‐trimethylchinon‐1.4‐yl‐alkane als modellsubstanzen für polymere hydrochinon‐chinon‐redoxysysteme. VI. Synthese und untersuchung des redoxverhaltens durch potentiometrische titration und polarographie
Authors: Förster Von H. J. , Manecke G. 
Published: April 2003

AbstractEs wurden das Bis‐trimethylchinon‐1.4‐yl‐methan, ‐äthan und ‐propan als symmetrisch aufgebaute, tetravalente Modellsubstanzen für polymere Hydrochinon‐Chinon‐Redox‐systeme synthetisiert. Die Verbindungen wurden durch potentiometrische Titration und Polarographie untersucht. Die Titrationskurven und Polarogramme werden theoretisch gedeutet. Die gegenseitige Beeinflussung der bivalenten Redoxeinheiten wird mit Hilfe eines induktiven Modells diskutiert.
Über oligomere und polymere 2.5‐dimethoxyphenylen‐vinylene
Authors: Manecke Von G. , Zerpner D. 
Published: April 2003

AbstractPoly‐2.5‐dimethoxyphenylen‐(1.4)‐vinylen und eine Reihe oligomerer 1.4‐verknüpfter Modellsubstanzen der Formel 2.5‐(CH3O)2‐4‐RC6H2CHCH[2.5‐(CH3O)2C6H2CHCH]n2.5‐(CH3O)2‐4‐R (n = 0 bis 4; R  CH3, H, CHO) wurden synthetisiert. Poly‐2.5‐dimethoxyphenylen‐(1.3)‐vinylen und die 1.3‐verknüpften Oligomeren (n = 0, 1; R  H, CHO) wurden ebenfalls erhalten. Die Darstellung der Verbindungen erfolgte mit Hilfe der WITTIGschen Reaktion aus Triphenylphosphoniumsalzen wie 2.5‐(CH3O)2C6H3CH2P(C6H5)3Br, 2.5‐(CH3O)2C6H21.3‐[CH2P(C6H5)3Br]2 oder 2.5‐(CH3O)2‐4‐CH3C6H2CHCH2.5‐(CH3O)2C6H2‐4‐CH2P(C6H5)3Br und Aldehyden wie 2.5‐Dimethoxyisophthalaldehyd, 4.4′‐Diformyl‐2.2′.5.5′‐tetramethoxystilben oder 4‐Formyl‐4′‐methyl‐2.2′.5.5′‐tetramethoxystilben. Hydrierung der Vinylen‐Brücken bei den Verbindungen mit n = 1 ergab die zu erwartenden 2.5‐Dimethoxyphenylenäthylene. Die Entmethylierung der 2.5‐Dimethoxyphenylenvinylene bzw. ‐äthylene (n = 1) führte in den meisten Fällen zu den entsprechenden Hydroxy‐Verbindungen.
Über aromatische polyamide mit heterocyclischen ringsystemen
Authors: Künzel Von H.‐E. , Wolf G. D. , Bentz F. , Blankenstein G. , Nischk G. E. 
Published: April 2003

AbstractZur Herstellung von hochmolekularen aromatischen Polyamiden, die in polaren Lösungsmitteln löslich sind, wurden neue aromatische Diamine mit Oxdiazol‐, Triazol‐, Thiadiazol‐, Thiazol‐, Hydantoin‐, Chinazolon‐ und Chinazolindion‐Ringsystemen, die zum Teil auch noch Äther‐ oder Sulfongruppen enthalten, mit aromatischen Dicarbonsäuredichloriden (z. B. Iso‐ oder Terephthaloyldichlorid) in polaren organischen Lösungsmitteln (z. B. N.N‐Dimethylacetamid oder N‐Methylpyrrolidon) umgesetzt.Es konnten Fäden und Fasern hergestellt werden, die eine sehr gute Festigkeit und eine hohe Temperaturbeständigkeit aufweisen. Polyamide aus Diaminen mit Chinazolindion‐Ringsystemen waren thermisch am beständigsten und zeichnen sich außerdem durch eine sehr geringe Brennbarkeit aus.Aus ihren Lösungen in polaren Lösungsmitteln lassen sich die neuen Polyamide auch zu geschmeidigen, hochtemperaturbeständigen Filmen verarbeiten.
Polymérisation anionique du sulfure d'isobutène. Préparation de copolymères statistiques et séquencés
Authors: Boileau Par Sylvie , Sigwalt Pierre 
Published: April 2003

AbstractDes homopolymères cristallins du sulfure d'isobutène (épithio isobutane) ont été obtenus par polymérisation anionique, ainsi que des copolymères statistiques et séquencés avec le sulfure de propylène. Les copolymères solubles ont des masses moléculaires en accord avec les masses théoriques, ce qui montre que la polymérisation se produit sans réaction de terminaison.Les amorceurs conduisant à des polymères bifonctionnels (renfermant deux centres actifs) comme le naphthalène‐sodium ou le naphthalène‐potassium, ont donné des copolymères à trois séquences, dont deux séquences cristallines de polysulfure d'isobutène. Ces copolymères sont insolubles dans le toluène à 37°C, alors que des copolymères de même masse moléculaire et de même composition, mais renfermant seulement deux séquences, sont solubles. Ceci montre l'influence sensible sur les propriétés physiques des différents types d'association intermoléculaire par l'intermédiaire de réseau cristallin.
Über polyenarylene und polyenheteroarylene. 2. Mitt.: Poly‐[thienylen‐(2.5)‐äthenamer‐alt‐phenylen‐(p,m,o)‐äthenamer] und einige oligomere. Synthese, spektrales verhalten und elektrische leitfähigkeit
Authors: Kossmehl Von Gerhard , Härtel Manfred , Manecke Georg 
Published: April 2003

AbstractBei der WITTIG‐Reaktion von 2.5‐Bis‐(triphenylphosphoniomethyl)‐thiophen‐dichlorid mit Terephthalaldehyd, Isophthalaldehyd und Phthalaldehyd wurden die Poly‐[thienylen‐(2.5)‐äthenamer‐alt‐phenylen‐(p,m,o)‐äthenamere] erhalten. Diese Polymeren enthalten endständige Aldehydgruppen. Analog wurden die Poly‐[phenylen‐p‐äthenamer‐alt‐phenylen‐(p,m,o)‐äthenamere] hergestellt sowie einige Oligomere mit 3 Aromatenbausteinen und 2 Vinylengruppen sowie 5 Aromatenbausteinen und 4 Vinylengruppen. Diese Polymeren und Oligomeren sowie das Poly‐[thienylen‐(2.5)‐äthenamer] wurden durch UV‐Spektren, Spektren des sichtbaren Bereiches, IR‐Spektren und Massenspektren charakterisiert. Es wurden auch Untersuchungen mit Röntgenstrahlen zur Ermittlung des Festkörperaufbaus angestellt. Alle Oligomeren und Polymeren wurden auf ihre elektrische Leitfähigkeit untersucht.
Poly‐p‐xylyliden. Synthesen und beziehungen zwischen struktur und elektrophysikalischen eigenschaften
Authors: Hörhold Von Hans‐Heinrich , Opfermann Johannes 
Published: April 2003

AbstractPoly‐p‐xylyliden (I) wird durch bifunktionelle Carbonylolefinierung von Terephthalaldehyd nach der WITTIGschen Reaktion und mitp‐Xylylen‐bis‐[phosphonsäurediäthylester] sowie durch Dehydrochlorierung vonp‐Xylylendichlorid mit Natriumhydrid in Dimethylformamid und mit Kaliumamid in flüssigem Ammoniak hergestellt und vergleichend untersucht. Methyl‐ und methoxysubstituierte Poly‐p‐xylylidene (II) und (III) werden aus 2.5‐Bis‐[chlormethyl]‐p‐xylol und ‐hydrochinondimethyläther erhalten. I—III werden durch IR‐ und Reflexionsspektren und durch Thermogravimetrie analysiert.magnified imageDie Polyxylylidene I—III besitzen Halbleitereigenschaften und Photoleitfähigkeit. Typische Werte für die Dunkelleitfähigkeit und Aktivierungsenergie von I sind σ400°K ≈ 10−15Ohm−1cm−1und ED= 2,4 eV.Absorptions‐ und Leitfähigkeitsspektren fallen in den gleichen Spektralbereich, wobei die Photoleitfähigkeit an der langwelligen Kante der Absorption ein Maximum besitzt. Die Anregungsenergie für die Grenze der Photoleitung von I, E0= 2,35 eV, besitzt dieselbe Größe wie EDund ist annähernd in Übereinstimmung mit dem theoretisch berechneten Wert für den π–π*‐Übergang des isolierten Makromoleküls. Bei den substituierten Polyxylylidenen II und III ergeben sich entsprechende Beziehungen.Ferner wird zur näheren Charakterisierung der Leitungsphänomene die Abhängigkeit des Photostromes und dessen Relaxationszeit von der Spannung, der Temperatur und der Bestrahlungsstärke gemessen sowie die Photoleitfähigkeit bei kombinierter optischer Anregung und der Einfluß von Sauerstoff auf die Photoleitung untersucht.
Free radical polymerization of unconjugated dienes. IX. Kinetic evidence of formation of five and six membered rings in the free radical polymerization of divinylether
Authors: Guaita Marino , Camino Giovanni , Trossarelli Luigi 
Published: April 2003

AbstractSome kinetic relationships between the monomer concentration and the composition of the polymers from 1.4‐dienes, in terms of monomeric and structural units, are derived taking into account all the cyclization reactions which can occur in the course of the chain growth. These relationships are applied to the results of the analytical determination of the residual unsaturations in the products of the free radical polymerization at 70°C of divinylether in benzene solutions. It is shown that the chain growth takes place exclusively by addition of cyclic radicals onto monomer molecules. Evidence is given that both five and six membered rings are formed in the cyclization steps.
Structure of solution grafted polybutadiene
Authors: Wetton R. E. , Moore J. D. , Fox B. E. 
Published: April 2003

AbstractThree different polybutadienes possessing widely different vinyl and cis monomer structures have been grafted with methyl methacrylate in solution using both benzoyl peroxide and azobisisobutyronitrile catalysts. Careful fractionation and backbone degradation techniques together with molecular weight determinations lead to the conclusions that both catalysts gave graft copolymer in the 10% rubber solutions used. Benzoyl peroxide always gave better graft efficiencies, (as did high vinyl and to a lesser extent high cis polybutadiene). The molecular weight of the polymethylmethacrylate grafts are slightly lower than those of homopolymers polymerized under the same conditions indicating < 20% grafting by chain transfer and termination mainly by disproportionation.
Molecular weight distribution of crystalline polypropylene
Authors: Yamaguchi Kinya 
Published: April 2003

AbstractThe molecular weight distribution of several polypropylene samples was studied by the column elution method. With the exception of a lower molecular weight sample, the molecular weight distribution curves were found to be well described by a revised log‐normal function presented by DAVIS et al. The molecular weights Mw and Mn observed by direct measurements for the whole polymers were in good agreement with the corresponding ones calculated from their molecular weight distribution curves according to this function. Moreover, no anomalous relation was found between the solution viscosity and the molecular weight for several unfractionated polymers and their high molecular weight fractions. These results reveal that there exists no long chain branch even in the high molecular weight region, and that the approximation of the distribution pattern by this revised lognormal function sufficiently characterizes polypropylene samples. The values of Mw/Mn of all samples studied were within a narrow range from 6 to 9, and no distinct dependency of the molecular weight distribution on the average molecular weight was observed.
The mechanism for the oxidative polymerization of p‐phenylenediamine in aqueous solution of iron chelate
Authors: Tsuchida Eishun , Kaneko Masao , Kurimura Yoshimi 
Published: April 2003

Abstractp‐Phenylenediamine (PD) was oxidatively polymerized in an aqueous solution of iron chelates, e.g., the Fe(III)‐salt of ethylenediaminetetraacetic acid; poly(azophenylene) was formed as a black powder.The ferric chelate is effective for the polymerization, and the polymer yield is proportional to the oxygen consumption. As a rule, the rate of polymerization reaches a maximum at pH 7–8.The electrochemical potential of the system changes rapidly during the initial stage of the polymerization and reaches an equilibrium value within several minutes. This shows that the polymerization proceeds while the equilibrium of ferric and ferrous chelates is maintained.The mechanism of the polymerization is considered to involve an equimolar coordination of the unprotonated species of PD to the ferric chelate, thus forming a mixed complex. PD is activated by electron transfer to the ferric ion which is thereby reduced to the ferrous ion, and the activated PD molecules couple with each other. The ferrous chelate is then oxidized by oxygen to the ferric chelate and may act as a catalyst again.The rate‐determining step of the polymerization is the oxidation reaction of ferrous to ferric chelate by oxygen. However, the rate of the polymerization is also affected by the equilibrium between the iron chelate and PD in the polymerization system.
Polyaddition reactions of SCHIFF's bases and diisocyanates
Authors: Harada Kunihiro , Mizoe Yoji , Furukawa Junji , Yamashita Shinzo 
Published: April 2003

AbstractNew polymers were obtained by polyaddition reactions of various SCHIFF's bases and diisocyanates. The structure of the polymers obtained was investigated by model reactions and thermal analysis. The results show that there are several reaction modes in these polyaddition reactions and the polymers hardly have the simple and regular structure.
Synthese von Äthylenterephthalat‐oligomeren mit hilfe von tert‐butylschutzgruppen,
Authors: Pénisson Von René , Zahn Helmut 
Published: April 2003

AbstractTerephthalsäure‐mono‐tert‐butyloxyäthylesterchlorid ist ein geeignetes Ausgangsprodukt zur Synthese von äthylenterephthalat‐Oligomeren, da eine selektive Abspaltung der tert‐Butylschutzgruppe mit Trifluoressigsäure neben den Terephthalsäureglykolesterbindungen gelang. Versuche, pleionomere äthylenterephthalate durch eine MERRIFIELD‐Synthese mit dem tert‐butylgeschützten Säurechlorid als Baustein aufzubauen, verliefen unbefriedigend.