bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zum fällungsverhalten von mischungen polymerhomologer substanzen
Authors: Klein Von J. , Wittenberger U. 
Published: April 2003

AbstractMischungen von einheitlichen, homologen Polymerproben wurden in verdünnter Lösung auf ihr Fällungsverhalten untersucht. Es konnte eindeutig gezeigt werden, daß die Beimengung einer niedermolekulareren Polymerkomponente B nicht löslichkeitsvermittelnd, sondern löslichkeitsvermindernd auf eine höhermolekulare Komponente A wirkt. Dabei stellen allein die Partialkonzentrationen der einzelnen Polymerkomponenten das entscheidende Kriterium für das Fällungsverhalten einer Mischung dar.Die aus der Löslichkeitsverminderung resultierende Veränderung der Gleichgewichtskonzentration der Komponente A wird durch einen Aktivitätskoeffizienten f ≥ 1 erfaßt, dessen Größe und Abhängigkeit von den verschiedenen Parametern bestimmt wurden.Die vorliegenden Ergebnisse basieren im wesentlichen auf Untersuchungen in Mischlösern, sie beziehen jedoch Lösungen von Polymeren in einem Θ‐Lösungsmittel mit ein.
Photochemical degradation of cellulose material
Authors: Desai R. L. , Shields J. A. 
Published: April 2003

AbstractCellulose has been irradiated by ultraviolet light. The degradation was followed viscometrically and by weight loss measurements. The changes in the degree of Polymerization and weight of the irradiated material indicated that the degradation is random and follows first order kinetics. It is suggested that chain scission is the primary process yielding glucose and oligosaccharides. Gas chromatography of the volatile products indicated the presence of acetaldehyde, propionaldehyde, methyl formate, acetone, methanol, ethanol, methane and ethane which have not been reported in earlier studies. These compounds could result from further degradation of glucose and oligosaccharides formed during the initial chain scission process.
Modelle und modellreaktionen für die halogenierung von cis‐ und trans‐1.4‐polybutadien. Ein beitrag zur stereochemie der „kopf‐kopf‐polyvinylhalogenide”︁
Authors: Hörhold Von Hans‐Heinrich , Kühmstedt Rolf , Hindersin Peter , Dawczynski Hans , Drefahl Günther 
Published: April 2003

AbstractAls Reaktionsmodelle für cis‐ und trans‐ 1.4‐Polybutadien wurden die all‐cis‐ und all‐trans‐Isomeren von
magnified image
synthetisiert. Die Halogenierung mit Pyridiniumperbromid und Pyridiniumperchlorid führt zu
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die Modelle für Kopf‐Kopf‐Polyvinylhalogenide darstellen. Trans‐Olefine ergeben Strukturelemente mit erythro‐, cis‐Olefine mit threo‐Konfiguration. Aus Infrarot‐ und RAMAN‐Spektren werden die für trans‐ und gauche‐Stellung der benachbarten Halogenatome charakteristischen CX‐Frequenzen ermittelt: trans‐Stellung νCBr 550–560 cm−1 (IR), 595 bis 620 cm−1 (Ra), νCCl 650–660 cm−1 (IR), 670–690 cm−1 (Ra), gauche‐Stellung νCBr 520–535 cm−1 (IR, Ra), νCCl 550–560 cm−1 und 590–610 cm−1 (IR, Ra). Mit diesen Werten wird eine lokale Konformationsanalyse der Halogenierungsprodukte von cis‐ und trans‐1.4‐Polybutadien durchgeführt.
Some remarks on macromolecular asymmetric syntheses
Authors: Farina Mario 
Published: April 2003

AbstractThe probability parameters that govern asymmetric polymerization can be expressed in terms of free energy of activation. In the case of asymmetric MARKOV chains optical purity depends on two factors, one properly related to asymmetric induction, the other to stereoregularity. This treatment shows that in proper conditions ‐ the asymmetric energy being the same ‐ asymmetric polymerization gives rise to products with higher optical purity than the usual asymmetric syntheses.
Polymers and copolymers containing D‐galactose residues
Authors: Black William Aird Peden , Colquhoun Joseph Adams , Dewar Eric Thomas 
Published: April 2003

AbstractPolymers and copolymers based on the 6‐methacrylate ester, the 6‐acrylate ester, and the 6‐O‐allyl ether of 1.2:3.4‐di‐O‐isopropylidene‐α‐D‐galactopyranose (diisopropylidenegalactose), and the 1‐methacrylate ester of 2.3‐O‐isopropylideneglycerol, have been synthesised and characterised by chemical and infrared analysis. Methods have been developed for removing the protecting isopropylidene groups from the polymerised products to reveal the hydrophilic, hydroxylated carbohydrate residues.By comparing the properties (e.g. glass transition temperature, hydrolysis of isopropylidene residues, and crosslinking reactions) of galactose methacrylate and glycerol methacrylate polymers, it is possible to assess the influence of the heterocyclic ring and glycosidic hydroxyl group of the galactose moiety in synthetic polymer systems.A series of galactose methacrylate‐methyl methacrylate random copolymers, containing different proportions of sugar residues, has been prepared, and it has been shown that the hydrophilic properties can be accurately controlled by the amount of galactose methacrylate in the copolymer. The industrial significance of this is discussed.Successful copolymerisations of diisopropylidenegalactose acrylate and methyl acrylate, diisopropylidenegalactose methacrylate and styrene, diisopropylidenegalactose acrylate and acrylonitrile, diisopropylidenegalactose methacrylate and vinyl acetate, and allyl diisopropylidenegalactose and maleic anhydride are described, and in most cases the copolymers have been readily deacetonated and characterised by phenylhydrazone formation.Evidence is presented to show that, in general, the introduction of reducing sugar units is a convenient method of increasing the reactivity and hydrophilicity of synthetic polymers and copolymers.
Optical activity of poly(methacrylic acid) salts with nicotine in aqueous solution
Authors: Michailov Marin , Baldjieva Raina 
Published: April 2003

AbstractThe concentration dependence of the optical activity of nicotine salts of atactic and isotactic poly(methacrylic acid) as well as the nicotine salt of pivalic acid and nicotine in dilute aqueous solutions without added electrolyte has been studied. It was found that [α]λ does not vary linearly with the concentration. The optical activity of the nicotine salt solutions of poly(methacrylic acid) calculated on the basis of the specific rotations of nicotine cation and nicotine base molecule differs appreciably from the measured one. This difference is explained by the assumption of a higher specific rotation of the associated nicotine cation.
The unperturbed dimensions of polymethyl methacrylate
Authors: Gundiah S. , Mohite R. B. , Kapur S. L. 
Published: April 2003

AbstractThe value of KΘ obtained from [η] method is higher than the value of KΘ obtained from the measurements in Θ‐solvent and over 100% higher than the value of KΘ obtained from the data using FOX‐FLORY‐SCHAEFGEN and other equivalent plots. The higher value of KΘ indicates that the unperturbed dimensions of PMMA are 30% higher in bulk than in dilute solutions perhaps due to influence of the microstructure on the unperturbed dimensions of the polymeric chains.
Vinyl polymerization. 236. Inhibiting effect of verdazyl in radical polymerization; mechanism of inhibition reaction
Authors: Kinoshita Masayoshi , Miura Yozo 
Published: April 2003

AbstractVerdazyl, a new type of stable free radical, was found to inhibit effectively the radical polymerization of styrene and methyl methacrylate. Inhibition period measured by dilatomethry was proportional to the concentration of verdazyl. The reaction prodacts formed in the system such as N‐benyl‐verdazyl, N‐2‐(2‐carbomethoxy)propyl‐verdazyl and the deduced reaction product, leucoverdazyl, had no effect on the measurement of inhibition period. 2‐(2‐Cyano)propyl‐verdazyl dissociates at temperatures over 40°C but does not interfere the determination of inhibition period at 30°C. The rate of initiation reaction and the ratio of rate constants, k2p/2kt, which were calculated from the consumption rate ofDPPH and from the relationship between polymerization rate and the degree of polymerization. The absorption of verdazyl, at 720 mμ enables to measure inhibition periods from the change of the intensity of the absorption. Polymerizations of vinyl chloride and acrylontrile were also inhibited by verdazyl. Determination of the inhibition period for vinyl acetate was difficult, because the time‐conversion curves after the inhibition period were not linear. Polymeric verdazyl also inhibits the radical polymerization of Vinyl monomers.
Cationic polymerization and copolymerization of vinylferrocene
Authors: Aso Chuji , Kunitake Toyoki , Nakashima Toshihide 
Published: April 2003

AbstractVinylferrocene was shown to undergo readily cationic polymerization by FRIEDEL‐CRAFTS and other cationic catalysts. The polymers obtained possessed rather low molecular weights, the highest being 3500. In spite of the high reactivity of the ferrocene nucleus towards electrophilic substitution, no mode of propagation other than vinyl addition was detected when the infrared spectra of polymers prepared by cationic and free radical reactions were compared. The electronic spectra of polyvinylferrocene and its oxidized form were similar to those of ferrocene and ferricinium ion, respectively. In the cationie copolymerization with styrene, the latter was incorporated into the polymer only when the styrene content in the monomer feed exceeded 90%. The copolymerization with vinyl isobutyl ether (M2) by BF3OEt2 in toluene at 0°C gave the reactivity ratios: r1 = 0.1 ± 0.1, r2 = 9.7 ± 1.0. The high cationic reactivity of vinylferrocene is consistent with the stability of the α‐ferrocenylearbonium ion inferred from solvolysis and other reactions.
Polymerization of N‐vinylearbazole with vanadium compounds. Part I. Polymerization with vanadium pentoxide and metal vanadates
Authors: Biswas Mukul , Maiti M. M. , Ganguly N. D. 
Published: April 2003

AbstractBulk polymerization of N‐Vinylcarbazole (NVC) has been carried out using vanadium pentoxide as the contact catalyst. The rate of polymerizatlon has been found to depend upon catalyst to monomer ratio. A cationic mechanism has been suggested and the role of V2O5 surface in the polymerization has been tentatively analyzed. The π‐acid characteristies of V5⊕ ion is believed to be involved in initiating the polymerization. The effect of a number of additives on the polymerization rate has been studied, which endorses the cationic mechanism. The catalytic efficiency of a number of metal vanadates for the polymerization of NVC has also been studied. A fairly good correlation between the activity and electronegativity of the metallic moiety has been established.
Triazin‐polymere. II. Polyphenylentriazine
Authors: Greth Von Erich , Elias Hans‐Georg 
Published: April 2003

AbstractDie Kondensation von Benzamidinhydrochlorid mit Acetanhydrid zu 2‐Methyl‐4.6‐diphenyl‐s‐triazin verläuft mit Ausbeuten von mehr als 90%. Die entsprechende Reaktion von Terephthaldiamidindihydrochlorid führt zu in konz. Schwefelsäure löslichem Poly{[6‐methyl‐s‐triazinylen‐(2.4)]‐1.4‐phenylen} mit niedrigem Polymerisationsgrad. Benzamidin‐N‐carbonsäureäthylester geht beim Erhitzen mit 99% Ausbeute in 2‐Hydroxy‐4.6‐diphenyl‐s‐triazin über. Terephthaldiamidin‐di‐N‐carbonsäureäthylester zersetzt sich beim Erhitzen unter Abspaltung von Äthylcarbamat zum unlöslichen weißen Poly{[6‐hydroxy‐s‐triazinylen‐(2.4)]‐1.4‐phenylen}.
Investigations of the structure of ethylene‐propylene and ethylene‐butene copolymer crystals using fuming nitric acid. Part II. The removal of branches by nitric acid
Authors: Holdsworth P. J. , Keller A. 
Published: April 2003

AbstractThe structure of random ethylene‐propylene and ethylene‐butene copolymer crystals has been investigated using fuming nitric acid. This paper is concerned with the removal of branches by nitric acid from crystals grown from two special carbon‐14 labelled copolymers. In addition to changes in branch content, weight losses and changes in long periods, melting behaviour and unit cell spacings which result from nitric acit treatment are reported. The results indicate that branches are contained within the crystalline cores of the lamellar crystals of the ethylene‐propylene and the ethylene‐butene copolymers.
Polymerization of α‐hydroxy‐carboxylic acid anhydrosulfites by tertiary amines or tertiary amides as catalysts
Authors: Inoue Shohei , Tsubaki Kazumi , Tsuruta Teiji 
Published: April 2003

AbstractPolymerization of α‐hydroxyisobutyric acid anhydrosulfite and α‐hydroxy‐chloroisobutyric acid anhydrosulfite is catalyzed at room temperature by tertiary amines (triethylamine, pyridine) or tertiary amides (N.N‐dimethylformamide, N.N‐dimethylacetamide). Polymerization of the latter monomer catalyzed by brucine caused asymmetric selection of the monomer antipodes. Infrared spectra and other studies of the system were made to clarify the mechanism.
Crystallization of polymer‐diluent systems. IV. Polyethylene oxide‐diethyl sebacate system
Authors: Jain N. L. 
Published: April 2003

AbstractThe crystal growth rate data in the polyethylene oxide‐diethyl sebacate system have been analysed, applying nucleation theory. It is shown that with reasonable adjustment in equilibrium melting temperature, Tm, the results follow both 2‐dimensional and 3‐dimensional mechanism as in the case of bulk polymers. No decision about the mechanism, therefore, could be concluded. However, it is shown that polymer‐diluent systems can also be represented on the same single straight line of bulk polymers if proper values for activation energy, ED, and Tm are given to the system.
The Effect of Amines on the Cadmium bis (allyl mercaptide) initiated Polymerisation of Propylene Sulphide
Authors: Morgan D. R. , Wragg R. T. 
Published: April 2003

AbstractAliphatic amines have a marked influence on the polymerisation of propylene sulphide initiated by metal mercaptides. The nature and magnitude of this effect, for cadmium bis (allyl mercaptide) initiated polymerisations, has been determined. The rate of polymerisation is decreased by primary amines and diamines, but increased by secondary and tertiary amines. The molecular weight of the polymer is reduced by primary and secondary amines but is virtually unaffected by tertiary amines.
Über die Polymerisation des 2‐Vinylindazols und einiger Indazolderivate
Authors: Hopff Von Heinrich , Perlstein Paul 
Published: April 2003

AbstractEs wurden ungesättigte Derivate des Indazols hergestellt und auf ihre Polymerisationsfähigkeit untersucht. 2‐Vinylindazol konnte radikalisch und thermisch polymerisiert werden. N‐(α‐Methylvinyl)‐indazol konnte nicht homopolymerisiert werden, dagegen gelang die Copolymerisation mit Styrol (r1 = 0,5; r2 = 0,75). Indazol‐1‐acetyl‐3‐carbonsäurevinylester wurde radikalisch und ionisch in Lösung polymerisiert. Die Glastemperaturen lagen in beiden Fällen bei 150°C. 2‐Vinyl‐6‐nitroindazol war nicht polymerisierbar. 1‐ und 2‐Allylindazol konnten mit n‐Butyl‐Lithium in Tetrahydrofuran polymerisiert werden.
Metal‐containing initiator systems. XIII. Free radical initiation of vinyl polymerization with systems containing metallic tin or tin compounds
Authors: Aoki Shuzo , Shirafuji Chiaki , Kusuki Yoshihiro , Otsu Takayuki 
Published: April 2003

AbstractAn investigation has been made on the polymerization of methyl methacrylate (MMA), with the following initiator systems: 1. binary system of metallic tin and benzyl chloride, 2. binary system of reduced nickel and tin tetrachloride, and 3. benzyltin compounds. All systems were found to initiate the radical polymerization of MMA.The rate of polymerization (Rp) of MMA initiated with tetrabenzyltin in benzene at 80°C may be expressed as follows:

The overall activation energy for this polymerization was estimated to be 12.5 kcal/mole. Tetrabenzyltin was also observed to serve as a photosensitizer in the polymerization of MMA.It was also found that the system metallic tin/benzyl chloride induced selectively the cationic polymerization of isobutyl vinyl ether as well as the radical polymerization of MMA.
Polymerization initiated by an electron donor‐acceptor complex. Part III. Polymerization of methyl methacrylate initiated in the systems containing polymer electron donor, acceptor, and carbon tetrachloride
Authors: Matsuda Minoru , Ishioroshi Yasuhiro 
Published: April 2003

AbstractThe polymerization of methyl methacrylate can be easily initiated in systems containing poly‐2‐vinylpyridine (polymer electron donor), liquid sulfur dioxide (acceptor), and carbon tetrachloride. The various types of polymer electron donors and acceptors which range widely in their electron affinity were also examined. The addition of DPPH causes the retardation; a decrease in the poly‐2‐vinylpyridine concentration or an increase in the monomer concentration leads to a higher molecular weight of poly‐MMA. The values of kp/√kt obtained under the various polymerization conditions are satisfactorily consistent with the literature values, suggesting that the polymerization proceeds through free radical intermediates.
Strahlenchemische Copolymerisation des Styrols mit Vinylchlorid. I. Untersuchungen zum Mechanismus und zur Kinetik der Reaktion
Authors: Ryska Von M. , Schneider Ch. , Hummel D. O. 
Published: April 2003

AbstractVinylchlorid und Styrol wurden bei Temperaturen zwischen −78 und 50°C durch 60Co‐γ‐Strahlung copolymerisiert. Die Zusammensetzung der Copolymeren wurde in Abhängigkeit von der Temperatur und der Zusammensetzung des Monomergemisches bestimmt. Die formalen Copolymerisationsparameter wurden berechnet, und es wurde versucht, aus den IR‐Spektren der Copolymeren qualitative Aussagen über die Verteilung der Monomereinheiten in den unter verschiedenen Bedingungen hergestellten Copolymeren zu machen. Die Ergebnisse weisen darauf hin, daß die Copolymerisation bei Temperaturen von −78 bis +20°C teilweise nach einem radikalischen, teilweise nach einem ionischen Mechanismus verläuft.
Polyamides from unsaturated acids. I. Polyfumaramides from unsubstituted aliphatic diamines
Authors: Mortillaro Luigi , Russo Mario , Credali Lino , Guidotti Vincenzo 
Published: April 2003

AbstractHigh molecular weight polyamides were prepared from fumaric acid dichloride and unsubstituted aliphatic diamines, by the interfacial polycondensation method.The influence exerted by the molar ratio of the reagents, by their concentration, by the acceptor of the acid and by the nature of the organic solvent on both yield and inherent viscosity of the polyfumaramide obtained from trimethylenediamine was studied.The polymers obtained are partially crystalline and infusible; on heating under vacuum they degrade at about 290°C. They are soluble exclusively in strong acids, such as sulphuric and trifluoroacetic acids.
Disubstituierte carbamoyllactame und lactam‐N‐carbonsäureester als aktivatoren für die anionische lactampolymerisation
Authors: Falkenstein Von G. , Dörfel H. 
Published: April 2003

AbstractDurch Umsetzung von N.N‐disubstituierten Carbamidsäurechloriden mit Lactamen und von Lactam‐N‐carbonsäurechloriden mit mehrwertigen Alkoholen wurden bisher nicht bekannte disubstituierte Carbamoyllactame bzw. Lactam‐N‐carbonsäureester hergestellt. Ausgewählte Vertreter beider Substanzklassen erwiesen sich als vorzügliche Aktivatoren für die anionische Lactampolymerisation bei niedrigen Temperaturen (90–150°C). Die Wirksamkeit der Aktivatoren kann durch gezielte Einführung von Substituenten in großer Breite variiert werden.An einfachen Elektronenmodellen werden Möglichkeiten zur Optimierung der Aktivatoraktivität gezeigt. Richtgrößen hierfür sind die HAMMETT‐Substitutionskonstanten, die pKB‐Werte des Carbamoylstickstoffatoms der disubstituierten Carbamoyllactame und die Absorptionsbanden der exocyclischen Carbonylgruppen der Lactam‐N‐carbonsäureester.Die in Gegenwart der neuen Aktivatoren hergestellten Polymerisate zeichnen sich durch besonders günstige mechanische Eigenschaften aus.
Über die verschiedenen mittelwerte des molekulargewichts und die uneinheitlichkeit von naturkautschuk und synthetischem cis‐polyisopren
Authors: Soei Von Ng Tet , Schulz G. V. 
Published: April 2003

AbstractAn Naturkautschuk und einem cis‐Polyisopren von annähernd gleichem [η]‐Wert wurden Molekulargewichtsbestimmungen durch Diffusion‐Sedimentation, Osmose und Lichtstreuung gemacht. Aus den Mittelwerten M̄n (osmotisch) und M̄w (Lichtstreuung) wird die molekulare Uneinheitlichkeit bestimmt. Bei etwa gleichem M̄w (2·106) ist das osmotische Molekulargewicht M̄n bei Naturkautschuk 3,0·105 und beim synthetischen cis‐Polyisopren 6,2·105. Außerdem macht sich beim Naturkautschuk ein nur schwer entfernbarer Anteil von Mikrogelen bemerkbar.Da die Trägheitsradien und die Wechselwirkungsparameter mit den Lösungsmitteln für Natur‐ und Synthesekautschuk sich nur wenig unterscheiden, können technologische Unterschiede zwischen den beiden Polymeren, außer durch Beimengungen von Nichtkautschukbestandteilen, nur durch die unterschiedliche Molekulargewichtsverteilung bedingt sein.
Retardation of free radical polymerization by redox dyes. Effect of 2.6‐dichlorophenol indophenol in the polymerization of methyl methacrylate and styrene
Authors: Kar Indrajit , Mandal B. M. , Palit S. R. 
Published: April 2003

Abstract2.6‐Dichlorophenol indophenol, a redox dye, in its dissociated as well as undissociated form has been found to be a powerful retarder for the free radical polymerization of methyl methacrylate and styrene. The rate constants for the reaction of the dye with polymethyl methacrylate and polystyrene radicals are respectively 8 200 and 17 700 1. · mole−1sec−1 at 60°C. It has been found that for every dye molecule consumed the number of polymer radicals removed from the system lies between 1 and 2.
Chemical transformation of polymers. IV Synthesis of some polymer salts of streptomycin
Authors: Scondac Ioan , Roman‐Dǎneţ Adelheid 
Published: April 2003

AbstractIt is undertaken a qualitative analysis of the double exchange reaction between a polymer salt and a low molecular salt, in which a small size counterion was exchanged against a polyvalent counterion of considerably larger size.It is discussed the influence of the conformational steric hindering effect, the steric hindering effect of two neighbouring substituents, the ionic strength effect, etc., on the transformation degree.For the experiment, the double exchange reaction between the alkaline salts of some types of carboxylic polymers and the streptomycin sulphate has been chosen. According to the synthesis conditions one can obtain soluble and insoluble polymer streptomycin salts.
Die lichtstreuung von teilweise denaturierter DNS
Authors: Schurz Von J. , Gruber E. 
Published: April 2003

AbstractBei geeigneter Auswertung kann man bei Lichtstreuungsmessungen an hochpolymerer Desoxyribonuclein‐Säure eine Feinstruktur beobachten, die als Folge eines „Superknäuels”︁ gedeutet werden kann. Die quantitative Auswertung nach der Theorie von PTITZYN führt bei nativer Lachsspermien‐DNS auf einen Superknäuel, der aus 14 Helixzylindern von jeweils 1060 Å Länge besteht; diese sind durch gelockerte Gebiete verbunden. Durch Vergleich mit dem totalen Molekulargewicht kann der Denaturierungsgrad ermittelt werden.
Zur kinetik der thermischen polymerisation des styrols
Authors: Kirchner Von K. 
Published: April 2003

AbstractKinetische Untersuchungen zur thermischen Polymerisation in verschiedenen Lösungsmitteln und bei verschiedenen Temperaturen werden beschrieben. Der Isotopeneffekt beim 2.4.6‐Trideuterostyrol wird bei verschiedenen Temperaturen und Monomerkonzentrationen bestimmt. Die erhaltenen Ergebnisse stehen mit den Vorstellungen MAYOS über den Startschritt der thermischen Polymerisation in Einklang.