bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of styrene with titanium tetrachloride and lithium isoamyl
Authors: Deshpande A. B. , Subramanian R. V. , Kapur S. L. 
Published: April 2003

AbstractStyrene has been polymerized at 30°C with the catalyst system titanium tetrachloride‐lithium isoamyl. The rate constant and the activation energy have been determined. The molecular weight as well as the crystallinity decrease with trans ‐stilbene present. This effect was further studied in polymerization experiments with the ZIEGLER catalyst titanium tetrachloride aluminum triethyl.
Anionic telomerizations of butadiene with aromatic hydrocarbons. III. Chemical structure of telomer
Authors: Kume Shouji , Saka Hideo , Takahashi Akikazu , Nishikawa Gen , Hatano Masahiro , Kambara Shu 
Published: April 2003

AbstractThe chemical structure of telomer prepared by anionic polymerization of butadiene with the use of sodium catalyst in toluene/tetrahydroturan mixtures was investigated. These studies indicate that the telomer contains one phenyl group and one aliphatic methyl group in each molecule, which suggests growing anions in polymerization process are end‐methylene anions. The smallest telomer C6H5CH2C4H7 contains predominantly trans‐CHCH unit.
Studies on the structure of polyurethane elastomers. II. High resolution NMR spectroscopic determination of allophanate and biuret linkages in the cured polyurethane elastomer: Degradation by amine
Authors: Okuto Hiroshi 
Published: April 2003

AbstractThe high resolution NMR method which had been proved to be useful for the analysis of the linear polyurethanes was further applied to determine the allophanate and the biuret linkages in the cured polyurethane elastomers. The polyurethane elastomer cured with glycol or diamine was made soluble into DMSO, DMA etc. by degrading the allophanate and the biuret linkages with aliphatic primary amine. The NMR investigation of degradation products thus obtained gave the quantitative informations about the cross‐linkages present before the degradation.
A chemical means of distinguishing between conjugated and conjugated bonds
Authors: Peebles L. H. , Brandrup J. 
Published: April 2003

AbstractPolymers which contain conjugatedbonds (polyenes) cannot be distinguished from polymers containing conjugatedbonds (polyimines) by spectral means alone. A chemical means has been found for distinguishing between polyenes and polyimines. Polyenes can be hydrogenated with the aid of palladium supported on charcoal, whereas polymines cannot. On the other hand, polymines can be oxidized by basic hydrogen peroxide, whereas polyenes cannot. Models used for polyene systems were dehydrochlorinated poly(vinyl chloride) and β‐carotene. A model for the polyimine system was polysuccinonitrile. This polymer will pick up oxygen rapidly to form an imine‐nitrone random copolymer. Since discolored polyacrylonitrile, whether discolored by heat or by base, has a reactivity similar to the imine‐nitrone system, it is concluded that the species responsible for color in polyacrylonitrile consists of a conjugatedsystem and not of a conjugatedsystem.
Elementary reactions of metal alkyl in anionic polymerization. II. Reaction mode of n‐butyllithium in the initiation step of acrylonitrile and methacrylonitrile polymerization
Authors: Kawabata Nariyoshi , Tsuruta Teiji 
Published: April 2003

AbstractThe reaction of n‐butyllithium with acrylonitrile and methacrylonitrile in hexane and tetrahydrofuran was investigated under the usual polymerization conditions. n‐Butane formation and nitrile addition are important under these conditions. Acrylonitrile and methacrylonitrile have nearly the same reactivity towards n‐butyllithium in hexane, but in totrahydrofuran the methacrylonitrile is much less reactive.
Use of cuprous ion and metallic copper as initiators of aqueous vinyl polymerization
Authors: Mitra Bhairab Chandra , Ghosh Premamoy , Palit Santi R. 
Published: April 2003

AbstractCuprous chloride and copper powder (in acid media) initiate the aqueous polymerization of certain vinyl monomers such as methyl methacrylate, ethyl methacrylate, methacrylic acid and styrene but it fails in case of acrylonitrile, methyl acrylate, and acrylic acid under identical conditions. Catalyst exponent of this initiator (in acid aqueous media) with respect to methyl methacrylate is 0.38.Quantitative determination of end‐groups by dye techniques of the polymers obtained shows that about 2 hydroxyl end‐groups per chain are present under acidic conditions in presence of slight traces of oxygen but in rigorous absence of oxygen, very little OH end‐groups are found incorporated.The mechanism of initiation under different experimental condition is discussed.
Über den einfluß ungesättigter verbindungen auf die polymerisation des trioxans
Authors: Von Hermann H. D. 
Published: April 2003

AbstractDie Polymerisation des Trioxans in Gegenwart kleiner Mengen an ungesättigten Verbindungen als Kettenüberträer wird beschrieben. Sie führ zu Polymerisaten mit einein erhöhten alkali‐und temperaturbeständigen Antell. Die Kettenübertragung kann durch eine Anlagerung des Polyoxymethylen‐Kations an die Kohlenstoff‐Doppelbindung und anschlißende Abspaltung eines Protons erklärt werden. Daneben erfolgt in geringern Umfang, eine Copolymerisation, welche die Zunahme des stabilen Polymeranteils bewirkt.Die meisten der untersuchten ungesättigten Verbindungen erniedrigen den Umsatz bei der Trioxanpolymerisation. Als Ursache dafür ist eine aktivitAtshemmende Weebselwirkung zwischen Katalysator und ungesättigter Verbindung anzusehen.
Polymerisation von äthylenoxid mit dem kaliumalkoholat von 4‐benzolazo‐benzylalkohol. II. Die quantitative bestimmung einer übertragungsreaktion
Authors: Kämmerer Von Hermann , Grover Pran Nath 
Published: April 2003

AbstractDie Untersuchung von Polyäthylenoxiden, die mit dem Kaliumalkoholat von 4‐Benzolazo‐benzylalkohol und Äthylenoxid erhalten wurden, ergab, daß nicht jedes Polyäthylenoxidmolekül eine Endgruppc aus dein Polymerisationsstarter enthielt. Die vermutete Übertragungsreaktion mit Wasserspuren wurde folgendermaßen nachgewiesen und quantative bestimint. Eine quantitative Umsetzung der Polyäthylenoxide mit(4‐Benzolazobenzoesä‐)anhydrid gab mittels colorimetrischer Messungen den Gehalt an HO‐Endgruppen. Der Vergleich des Gehaltes an Endgruppen aus dem Starter mit dem HO‐Endgruppengehalt zeigte ein starkes Überwiegen der HO‐Endgruppen. Die Zahlenmittel der Molekulargewichte (M̄n) von Polyäthylenoxidfraktionen, die unter der Annahme berechnct wurden, daß Polymermoleküle mit einer Endgruppe aus dem Starter und einer HO‐Endgruppe neben Polymermolekülen mit zwei HO‐Endgruppen vorliegen, stimmten mit den viskosimetrisch bestimmten Molekulargewichten (M̄η) überein.Daneben lassen sich Molekulargewichte aus den Endgruppen berechnen, die aus dem Starter stammen, ohne eine 4UUbertragungsreaktion zu berücksichtigen. Aus den Gehalten der verschiedenen Endgruppen und aus den verschiedenen Molekulargewichten wird eine Übertragungsgleichung abgeleitet, die der von MAYO gegebenen entspricht.
Anorganische verbindungen als lösungsmittel für polymere und monomere. Polymerisationen in phosphoroxychlorid und thionylchlorid
Authors: Schulz Von Rolf C. , Wolf Rainer 
Published: April 2003

AbstractDie Löslichkeit verschiedener Monomerer, Polymerer und Polymerisationskatalasatoren in anorganischen Verbindungen wurde untersucht. Chloride und Oxychloride des Phosphors und Schwefels zeigten gute Lösungseigenschaften. Thionylchlorid und Phosphoroxychlorid wurden als Lösungsmittel bei der kationischen Polymerisation von Styrol, Isobutylvinyläther, 3,3‐Bis‐(chlormethyl)‐oxetan, Tetrahydrofuran und Epichlorhydrin eingeaetzt. Als geeignete Katalysatoren erwiesen sich hierbei Aluminiumchlorid und Eisentrichlorid. In Phosphoroxychlorid konnten Acrylnitril und Vinylchlorid radikalisch polymerisiert werden.
Copolymerization of methyl methacrylate: With methyl glycidyl itaconate and the reaction of the copolymer with secondary amine
Authors: Ariga N. , Uchiyama M. , Kurosaki T. , Iwakura Y. 
Published: April 2003

AbstractMethyl glycidyl itaconate (MGI) was prepared as a reactive monomer with an epoxy group in the molecule, and it was copolymerized with methyl methacrylate (MMA). The monomer reactivity ratio of MGI to MMA are r1 = 1.73 ± 0.05 (MMA) and r2 = 0.20 ± 0.02 (MGI). Compared with other common vinyl polymers, the copolymerization of MGI with MMA tended to form only a low molecular weight polymer. The inherent viscosity was 0.27.The MMA‐MGI copolymer was treated with an excess of the N‐methylbenzyllamine in dimethylformamide at three temperatures. The rates of the reaction obeyed a simple second order Kinetics. The energy of activation was 13.4 kcal./mole
Copolymerization of cyclic ethers with vinyl compounds. I. Copylymerization of epichlorohydrin, with styrene
Authors: Minoura Yuji , Mitoh Motonori 
Published: April 2003

AbstractThe copolymerization of epichlorohydrin with styrene borontrifluoride etherate was studied in benzene solution. The copolymer is a white solid completely soluble in common organic solvents. The epichlorohydrin content in the copolymer decreases rapidly at the initial stage of copolymerization and then gradually with polymerization time. It is considered that epichlorohydrin at first reacts rapidly with the catalyst to form a soluble polymer rich in epichlorohydrin. When the concentration of epichlorohydrin becomes low, the styrene takes part in the reaction owing to its increasing concentration. Although formation of homopolymeric polyepichlorohydrin must be considered, free polystyrene could not be found; this was confirmed by turbidity investigations of the copolymers.
Über ternäre assoziate als vorstufen des reaktionskomplexes der basenkatalysierten addition von äthylenoxid an phenol
Authors: Erlmeier Von R. , Patat F. 
Published: April 2003

AbstractBei der basenkatalysierten Addition von Äthylenoxid an Phenol in homogener Phase konnten als Vorstufen des kinetisch geforderten trimolekularen. Reaktionskomplexes ternäre Assoziate verschiedener Molekularität nachgewiesen werden. Bei kleinen Phenol und Katalysatorkonzentrationen bestimmt das Gleichgewicht zwischen den Reaktanten und ihrem ternären Assoziat die Reaktionsgeschwindigkeit. Bei großen Phenol‐ und Katalysatorkonzentrationen liegen praktisch nur ternäre Assoziate vor, und die Reaktionsgeschwindigkeit hängt von den Phenol‐Epoxid‐Einheiten in diesen Assoziaten ab.
Polymerisation des trioxans mit aluminiumorganischen verbindungen und titantetrachlorid
Authors: Kabaivanov Von W. , Matewa R. , Natov M. 
Published: April 2003

AbstractEs wird die Polymerisation von Trioxan in Schmelze unter der katalytischen Einwirkung von Organoaluminiumverbindungen und ihrer Gemische mit Titantetrachlorid beschrieben, welche rait guten Ausbeuten zu hochmolekularen Polyoxymethylenen führt. Der Einfluß der Temperatur und der Zeit auf den Polymerisationsprozeß sowic auf den Umsatz wurde bei verschiedenen Verhältnissen des Katalysatorsystems Al(C2H5)2X: TiCl4 antersucht. Es wird angenommen, daß es sich um eine kationische Kettenreaktion handelt.
Copolymerization of tetrahydrofuran with diketene
Authors: Tada Koichi , Yamada Yoshio , Saegusa Takeo , Furukawa Junji 
Published: April 2003

AbstractCopylymerization of tetrahydrofuran (THF) with diketene (DK) was carried out at O°C. using the triethylaluminum/water‐system as catalyst. The produced polymer was a yellow solid. The formation of a copolymer was shown by the existence of THF units in the benzene‐insoluble fraction of the polymeric product. The IR‐spectrum of the benzeneinsoluble fraction had a band which can be ascribed to the crystalline poly‐THF. Furthermore poly‐THF having molecular weights of 1,500 to 3,100 was isolated from the hydrolyzed mixture of the benzene‐insoluble fraction high yield; it has OH‐ and COOH‐end groups. These facts have been taken to assume that the copolymerization of THF with DK leads to the formation of block copolymers instead of random copolymers.
Optisches drehungsvermögen circulardichroismus und ultraviolett‐spektrum des kallikrein‐inaktivators
Authors: Scholtan Von W. , Rosenkranz H. 
Published: April 2003

AbstractDie Wellenlängenabhängigkeit des optischen Drehungsvermögens des Kallikrein‐Inaktivators (KI) (identisch mit dem KUNITZ‐Inhibitor = „pancreatic trypsin inhibitor”︁) läßt sich im Sichtbaren und nahen UV durch die Gleichungen von DRUDE, MOFFITT und YANG bzw. von SHECHTER und BLOUT darstellen. Die Dispersionskonstante λc = 234 mμ und die Konstante b0 = 169 bleiben bei pH‐Änderungen der Lösung zwischen 2 und 12 und ebenso in konzentrierten Harnstofflösungen und Chloräthanollösungen unverändert. Die Sekundärstruktur des KI ist daher unter diesen Versuchsbedingungen beständig.Die Rotationskonstante K und die Konstante a0 sind bei KI‐Präparaten, die mit, Komplexbildnern Assoziate zu bilden vermögen, von der Konzentration und vom pH‐Wert der Lösung abhängig.Zwischen der Größe des spezifischen Drehungsvermögens, der Rotationskonstante K bzw. der Konstante a0 und dem Molekulargewicht dieser Präparate besteht eine Relation. Die Änderung dieser Konstanten wird von der Änderung der Tertiär‐ bzw. Quartärstruktur des KI bedingt.Bei der Denaturierung des KI in alkalischen Lösungen (pH 12,5 und 13) nimmt das Molekulargewicht des KI zu und das spezifische Drehungsvermögen [α]578 ab.Die Kurve der Rotationsdispersion zeigt bei 225 mμ ein Minimum und bel 195 mμ ein Maximum des spezifischen Drehungsvermögens. Der ausgeprägte COTTON‐Effekt ist ein Hinweis dafür, daß Teile des KI‐Moleküls in geordneter Form vorliegen. Die Rotationsdispersionskurve des KI und der Circulardichroismus sind uncharakteristisch für die bekannten Strukturformen (z. B. α‐Helix).Das UV‐Spektrum des KI und der Circulardichroismus werden für verschiedene pH‐ Werte armittelt. Beide Größen werden vor allem vom Tyrosingehalt des KI bestimmt. Im UV‐Spektrum des reinen KI existieren zwei isosbestische Punkte, und zwar bei 271 und 283 mμ.Die Dissoziation der vier Tyrosingruppen erfolgt in zwei Phasen. Zwei Tyrosingruppen zeigen normales Dissoziationsverhalten (apparenter pK‐Wert 10,0). Die Dissoziation der 3. und 4. Tyrosingruppe erfolgt erst in alkalischer Lösung (apparenter pK‐ Wert = 12, 0) und ist irreversibel.
Synthèse de polysiloxanes organofonctionnels, 3. Les poly[(acétoxyméthylméthyl)siloxane]s et leurs modèles
Authors: Reyx Danièle , Guillaume Pierre 
Published: April 2003

AbstractThe capability of halogen displacement by metallic acetates in oxyhalomethylmethylsilanediyle units was studied on linear and cyclic model compounds and on homogeneous and heterogeneous polysiloxanes. By displacement of iodine oxyiodomethylmethylsilanediyle units were specifically and quantitatively transformed into acetoxymethylmethylsiloxane units. This displacement was found to be accompanied by rearrangement of siloxane linkages, however, cleavage of substituted methyl and of vinyl groups, as observed in the displacement of chlorine in oxychloromethylmethylsilanediyle units, was not observed.
Synthesis of polymers with primary amino end groups, 2. Synthesis of polyisoprene with primary amino end groups and poly(isoprene‐b‐γ‐benzyl‐L‐glutamate)s
Authors: Hattori Iwakazu , Hirao Akira , Yamaguchi Kazuo , Nakahama Seiichi , Yamazaki Noboru 
Published: April 2003

AbstractPrimary amine terminated polyisoprene 2 was produced by reaction of anionic living polyisoprene with one of the following protected aminating reagents: N‐(benzylidene)trimethylsilylamine (1a). N‐(1‐phenylpentylidene)trimethylsilylamine (1b), N‐benzylidenebenzenesulfeneamide (1c), or N,N‐bis(trimethylsilyl)‐2‐bromoethylamine (3). Especially with 1a, the terminal amino group was quantitatively introduced at the end of the polymer chain. 2 was found to initiate the polymerization of the N‐carboxy anhydride of γ‐benzyl‐L‐glutamate 5 to afford poly(isoprene‐b‐γ‐benzyl‐L‐glutamate) (6).
Role of cocatalysts in polymerizations initiated with benzyl derivatives of transition metals, 2. Polymerization of styrene
Authors: Martineau Dominique , Dumas Philippe , Sigwalt Pierre 
Published: April 2003

AbstractPolymerization of styrene in toluene solution at 50°C was found not to be initiated with sufficiently pure tetrabenzylzirconium or ‐titanium. However, a cocatalytic effect of water was observed with a maximum rate for a mole ratio H2O/Mt (Mt = Zr or Ti) close to 0,1. No activities were observed for the hypothetical compounds (C6H5CH2)3Mt—O—Mt(CH2C6H5)3. This cocatalytic effect was also observed with tribenzylchlorozirconium (1), tribenzylzirconiooxytriphenylsilane (2), or 6,6‐dibenzyl‐2,2,4,4‐tetramethyl‐1,3,5‐trioxa‐2,4‐disila‐6‐zirconacyclohexane (3). Styrene polymerizations were also initiated by supported catalysts obtained by reaction of Zr(CH2C6H5)4 with aluminium oxide or silicium oxide pre‐dried at various temperatures. The activities of such systems were equal or slightly lower than those obtained with the system Zr(CH2C6H5)4/H2O (mole ratio 10 : 1). The resulting polystyrenes have very high molecular weights with very broad distribution. Copolymerization experiments with methyl methacrylate gave as main product a copolymer containing only 4% of monomeric units of styrene. A discussion of all results led to the conclusion that the main polymerization involves an anionic‐type propagation.
Potentiometric titration of syndiotactic methacrylic acid/dimethacryloylamine copolymers
Authors: Ziegenberg Klaus , Klesper Ernst 
Published: April 2003

AbstractThe potentiometric titration of syndiotactic methacrylic acid/dimethacryloylamine (MMA‐MAI) copolymers is investigated. In contrast to copolymers studied before, MAA‐MAI copolymers possess a highly syndiotactic backbone structure, a compositional statistics known from NMR‐measurements, and a cyclic structure as a part of the chain. The statistics of the MAA‐units and MAI‐rings is nearly random with respect to the formation of imide rings, the rings introducing a trans and a gauche conformation for each ring. Plots of the apparent pK (pKapp) versus the degree of ionization α, or versus log [(1‐ α)/ α], indicate a change from a relatively dense coil (a‐state) to an extended coil (b‐state) when α is increased. The decisive parameter for pKapp in the b‐state and for the conformational transition of the a‐state to the b‐state is the charge density on the chain β. The transition takes place for all copolymer compositions in an interval of Δβ ≈1 but the interval is situated at lower absolute values of β for the copolymers with higher contents of MAI‐rings. The Δβ at lower β may be either due to a decrease in intramolecular attraction or to a higher electrostatic repulsion. The free enthalpy of the conformational transition is, however, approximately the same for copolymers with different MAI contents. This constancy of the free enthalpy points to a conformational transition which is energetically not much different for the MAA‐ and the MAI‐units in the chain.
Thermoelastic behaviour of segmented polyurethane elastomers
Authors: Dzierża Wilslaw 
Published: April 2003

AbstractThermoelastic (stress‐temperature) measurements in elongation were conducted on polyurethane elastomers of different chemical structure. Values of the temperature coefficient d In

of the unperturbed dimensions of the network chains and the fraction fe/f of the stress, which is due to energetic effects, were calculated from measurements of unswollen samples. The elastomers displayed some deviations in the thermoelastic behaviour from that predicted by the theory. It is found that the extent of those deviations depends on the chemical structure and the contents of stiff and soft segments in the polyurethane rubbers studied.
Radical polymerization of methyl methacrylate initiated by the liquid crystalline compound cholesteryl oleyl carbonate
Authors: Deshpande Dinkar D. , Aravindakshan Perincheery 
Published: April 2003

AbstractPolymerization of methyl methacrylate (MMA) and vinyl acetate (VAc) at 30, 55, 65, 75, and 85°C in the presence of the cholesteryl liquid crystal compound cholesteryl oleyl carbonate (CHOC) are reported. The conversion increases, whereas the molecular weight remains constant, with increase in concentration of CHOC in the range 0,2 to 0,6 mol‐%. The activation energy for the polymerization of MMA was found to be 66,3 kJ/mol. The polymerization is inhibited in the presence of the radical scavengers 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and hydroquinone. VAc does not polymerize in the presence of CHOC for 20 h at 65°C. The interaction between MMA and CHOC is investigated by viscometry of toluene solutions and by UV spectrophotometry of CCl4 solutions. The equilibrium constants and the molar absorption coefficients for a 1:1 complex for MMA‐CHOC and for a 2:1 complex for VAc‐CHOC are reported. A plausible mechanism for the spontaneous polymerization of MMA in the presence of CHOC is presented. The tacticities of the polymers formed in the presence of CHOC are discussed.
Polymerization of aromatic methacrylates to high degrees of conversion
Authors: Połowiński Stefan , Tarkowska Sylvia 
Published: April 2003

AbstractPolymerizations of 2,4,6‐tribromophenyl methacrylate (1a), p‐tolyl methacrylate (1b), p‐cyclohexylphenyl methacrylate (1c), and p‐methoxyphenyl methacrylate (1d) were carried out up to conversions higher than 99%. The kinetics of the process was followed by the refractometric technique using a He‐Ne laser as light source. The influence of the concentration of initiator on the appearing of the gel effect was examined, taking the polymerization of 1a as an example.
Modifizierte ionenaustauscherharze — synthese und eigenschaften, 2. Synthese sulfoethylierter und sulfopropylierter styrol‐divinylbenzol‐harze
Authors: Döscher Frank , Klein Joachim , Pohl Fritz , Widdecke Hartmut 
Published: April 2003

AbstractSulfomethylated and sulfopropylated resins were prepared by polymer analogous reactions, starting from macroporous poly(styrene‐co‐divinylbenzene) matrices. Different reaction paths were used in the synthesis. It could be shown that sulfoalkylation can be achieved directly by reaction of the polystyrene resins with sultones. Alternatively, haloalkylated matrices were prepared and by halogen/sulfo‐substitution the corresponding ion exchange resins.
A correlation of anodic peak potentials with HOMO energies of various monomers
Authors: Akbulut Ural , Toppare Levent , Türker Lemi 
Published: April 2003

AbstractElectroinitiated cationic polymerization of olefins can be initiated by direct electron transfer from the highest occupied molecular orbital (HOMO) of monomers, by constant potential electrolysis. Potentials, at which some monomers lose electrons, were measured by cyclic voltammetry. Measurements were made on a Pt electrode versus Ag0/Ag+, in acetonitrile. The measured anodic peak potentials (Ep,a) were correlated to HOMO energies (ϵm), calculated by Hückel molecular orbital (HMO) considerations for coplanar molecules. For methyl‐substituted monomers the ω‐technique was also applied. A linear equation has been developed for Ep,a as a function of ϵm, for styrene derivatives having +I and +E substituents.
Polybutadiène hydroxytéléchélique, 6. Cinétiques et thermodynamique de condensation de quelques monoalcools et du polybutadiéne hydroxytéléchélique anionique avec les monoisocyanates en l'absence de catalyseur
Authors: Ghafari Mahmoud El , Pham Quang‐Tho 
Published: April 2003

AbstractThe kinetics and thermodynamics of the spontaneous condensation between monoalcohols (trans‐2‐hexene‐1‐ol, 1‐octanol, geraniol) and commercial hydroxytelechelic polybutadiene G1000 with propyl isocyanate and phenyl isocyanate in toluene were examined. In all the condensations studied, the third order law is fulfilled. Deviations from the second order law are observed for conversions higher than 60 to 80%. In all cases, autoassociation of the alcohols plays an important role. The rate constants increase with decreasing concentration of hydroxyls and autocatalysis is noticeable. In comparison with the monoalcohols, the different behaviour of the G1000 diol should be due to its trend to be strongly associated by its two hydroxylated chain ends.