bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cationic copolymerization of cyclic ethers with vinyl compounds. III. Polymerization of styrene in the presence of polyepichlorohydrin
Authors: Minoura Yuji , Mitoh Motonori 
Published: April 2003

AbstractStyrene was polymerized in the presence of polyepichlorohydrin with borontrifluoride etherate as a catalyst. The product was fractionated and it was found that a copolymer of styrene and epichlorohydrin was formed. The activation energy for the incorporation of styrene is 26 kcal/mole which is higher than that usually found in cationic polymerizations. A possible mechanism for the formation of the copolymer is discussed.
Spektroskopische Untersuchungen an polymeren Donator‐Acceptor‐Komplexen und Synthese von polymeren Elektronendonatoren. II. Polymere und monomere Derivate von p‐Anisidin, p‐Phenylendiamin und Benzidin
Authors: Klöpffer Von Walter , Tacheci Heinrich , Willicks Winfried 
Published: April 2003

AbstractEs wurden verschiedene Typen von Polymeren hergestellt, die als Grundeinheiten Elektronendonatoren, und zwar Derivate des p‐Anisidins, des p‐Phenylendiamins und des Benzidins enthalten. Durch Zusatz verschiedener monomerer Elektronenacceptoren unterschiedlicher Elektronenaffinität wurden Donator‐Acceptor‐Komplexe dieser Polymeren erhalten und deren Absorptionsspektren in Lösung und im festen Zustand aufgenommen.Die Komplexe der polymeren p‐Phenylendiamin‐ und Benzidinderivate mit starken Acceptoren enthalten Radikalkationen, ähnlich wie die starken monomeren DA‐Komplexe.
Studies on polymers from cyclic dienes. VIII. Cationic polymerization of 1.3‐[dimethylcyclopentadiene] and a general mechanism for cationic polymerizations of cyclopentadiene derivatives
Authors: Asc Chuji , Ohara Osamu 
Published: April 2003

AbstractPolymerization of 1.3‐dimethylcyclopentadiene was carried out with FRIEDEL‐CRAFTS and ZIEGLER‐type catalysts. All polymers obtained were soluble. The polymers had 45 to 55% 1.4‐structure and 55−45% 3.4‐structure. The polymerization appears to go through a tertiary carbonium ion, in contrast to that of monosubstituted cyclopentadienes. In copolymerization of 1.3‐dimethylcyclopentadiene (M1) with cyclopentadiene (M2), the former showed higher reactivity: r1 = 6.85 ± 1.10, r2 = 0.30 ± 0.10, at −78°C.Comparison of the structures of polymers obtained by cationic polymerization of substituted cyclopentadienes revealed a general mechanism which explains the mode of the monomer addition.
Pulsradiolytische messung der geschwindigkeitskonstanten der kombination von polyäthylenoxid‐radikalen in wäßriger lösung
Authors: Borgwardt Von U. , Schnabel W. , Henglein A. 
Published: April 2003

AbstractOH‐Radikale aus der Radiolyse des Wassers greifen gelöstes Polyäthylenoxid unter Bildung seitenständiger Makroradikale an. Die UV‐Absorption dieser Radikale wurde untersucht. Aus dem Abklingen der Absorption nach einem kurzen Strahlpuls ließ sich die Geschwindigkeitskonstante der Kombination zweier Makroradikale errechnen. Die Geschwindigkeitskonstante wurde für Polyäthylenoxide verschiedenen Polymerisationsgrades (2 bis 3000) bestimmt. Sie nimmt mit steigender Kettenlänge ab. Die Ergebnisse werden verglichen mit Theorien von BENSON und NORTH sowie von BAGDASARIAN über die Abhängigkeit des Kettenabbruchs von Polymerisationen von der Kettenlänge der Makroradikale.
Thermal Stability of Polysulphone
Authors: Davis A. 
Published: April 2003

AbstractPolysulphone, prepared from 2.2‐bis(4‐hydroxyphenyl)propane and 4.4′‐dichlorodiphenyl sulphone, degrades when heated at 380°C i. vac. The mol. wt. increases with time of heating until after about 3 hrs gelation occurs. In addition to crosslinking scission processes have been shown to be important. Degradation is also accompanied by the evolution of gas – mainly SO2 and CH4. Other products include a number of substituted diphenyl ethers, phenol, the major non gaseous product, and a variety of other phenols. Solutions of the degraded polymers react with DPPH and suggest the accumulation of hydroxyl groups with time of heating. The range of products indicates that the ether, isopropylidene and sulphone groups linking the phenylene rings are involved in the degradation. The rates of the crosslinking, scission, hydroxyl accumulation and gas evolution processes have been evaluated and the possible reactions underlying these processes discussed.
The apparent partial compressibility of polymers and biopolymers in pure solvents as measured in the analytical ultracentrifuge
Authors: Dayantis Jean 
Published: April 2003

AbstractThe apparent partial compressibilities (APC) of the following polymers dissolved in various solvents were measured: polystyrene in benzene, in toluene and in chloroform; polymethyl‐methacrylate (PMMA) in benzene; poly‐L‐benzyl‐glutamate (PLBG) in dimethyl‐formamide (DMF) and lysozyme (egg white) in water. The measurements were carried out in an analytical ultracentrifuge using Schlieren optics to determine the baseline elevation as a function of the rotor angular speed. The APC value obtained for polystyrene in toluene is the same as that previously reported by ANDERSON who used a piezometric technique. The APC value of polystyrene in chloroform, however, is significantly lower. This is ascribed to solvation of the polystyrene segments by chloroform molecules. The APC value of PLBG in DMF is more than twice that of lysozyme in water. Both polymers having helicoidal structures, the lower value for lysozyme is presumably a consequence of hydration.The incidence of solvation effects on the FLORY‐HUGGINS interaction parameter χ is discussed in some detail.
Sur les systèmes catalytiques TiCl4‐Air3. II. Étude cinétique de la copolymérisation propylène‐butène‐1
Authors: Laputte Robert , Guyot Alain 
Published: April 2003

AbstractL'activité catalytique de système résultant de la réaction de TiCl4 avec Al(C2H5)3 effectuée in situ, vis‐à‐vis de l'homopolymérisation et de la copolymérisation du propylène et du butène‐1, a été mesurée à partir des vitesses initiales. L'influence des divers paramètres (température, concentration totale et concentration relative des constituants du système catalytique, additifs) a été examinée. En général, la réaction admet l'ordre 1 par rapport au monomère, l'ordre 2 par rapport à TiCl4 et les taux de réactivités sont: rp = 2,4 ± 0,4 (propylène) et rB = 0,5 ± 0,2 (butène‐1) pour le maximum d'activité. On propose que les catalyseurs comportent une distribution de sites d'activité et de spécificité variées.
Investigations on conformations of block and of random copolymers in dilute solution
Authors: Dondos Anastasios , Rempp Paul , Benoît Henri 
Published: April 2003

AbstractInvestigations on the viscosity behavior of well characterized block and random copolymers were carried out in a number of solvents. Account was taken of the expansion of the corresponding individual homopolymers in each of the chosen solvents. It was shown thus that for block copolymers heterocontact interactions do not affect the dimensions of the macromolecular coils. This confirms the “segregated” conformations of block‐copolymers, characterized by a very low number of intramolecular heterocontacts.On the contrary, for random copolymers the χAB term does not only affect the expansion but also the unperturbed dimensions of the molecule. The heterocontact interactions are, as expected, strongly solvent dependent, and a relation was established between the expansion increment and the critical demixtion volume of the corresponding homopolymers.
Charakterisierung adsorbierter makromolekülschichten durch ellipsometrie
Authors: Killmann Von Erwin , Wiegand Hans‐Günter 
Published: April 2003

AbstractDie Adsorption von Polyäthylenglykolen und Polyvinylpyrrolidon aus wäßrigen und methanolischen Lösungen heraus an glatten Chromoberflächen wird bei verschiedenen Temperaturen in einem weiten Konzentrationsbereich mit Hilfe eines Ellipsometers in situ untersucht.Die gemessenen Adsorptionszeitkurven und Isothermen für die adsorbierte Menge, die Dicke und Dichte der adsorbierten Schicht werden in Abhängigkeit von den Versuchsparametern diskutiert und daraus Vorstellungen über den Adsorptionsmechanismus und die Struktur der adsorbierten Schicht entwickelt. Bei niedriger Lösungskonzentration erfolgt die Adsorption in Schichten hoher Konzentration und geringer Dicke. Bei zunehmender Lösungskonzentration richtet sich das zunächst relativ flach aufliegende Molekül auf, so daß die Adsorptionsschicht dicker und weniger konzentriert ist.
Polymerization of cyclic SCHIFF's bases
Authors: Harada Kunihiro , Mizoe Yoji , Furukawa Junji , Yamashita Shinzo 
Published: April 2003

AbstractPolymerization of various cyclic SCHIFF's bases by cationic catalysts was attempted. It was found that a five membered cyclic SCHIFF's base such as 5.5‐dimethylpyrroline‐Δ1 gives a powdery product having a molecular weight of about 1,000 while six membered ones cannot be polymerized at all. Although the structure of the polymer obtained is much complicated, it was confirmed by various analytical techniques that the polymer contains some units arising from ring‐opening polymerization of 5.5‐dimethylpyrroline‐Δ1.
Theory of vapor pressure osmometry when ambient solvent vapor is unsaturated
Authors: Kamide Kenji , Sugamiya Ken , Nakayama Chozo 
Published: April 2003

AbstractThe general theory of the vapor pressure osmometry has been established, as an extension of the KAMIDE and SANADA theory, in the case when ambient vapor phase is unsaturated. The temperature difference (Tn–Tv)s at the steady state between a solution drop and a solvent drop can be expressed in a form of virial expansion of concentration c in the form:
with

equation image

Tn and Tv are the temperatures of the solution and solvent drops, respectively, M1 the molecular weight of the solute, A2,v the second virial coefficient, R the gas constant, Ts the temperature of ambient vapor phase, δH the molar heat of condensation of the solvent, k1n and k2n the coefficients of heat transfer at the interfaces between vapor and the solution drop and between the solution and the thermistor, respectively, A1n the surface area of the solution drop, A2n the surface area of the thermistor in contact with the solution. P0(Ts) saturated vapor pressure of the solvent at the temperature Ts, k′ the saturation coefficient defined by the ratio of the real unsaturated pressure of ambient vapor phase to the saturated pressure at the same temperature, and V0 the molar volume of the solvent.Theoretical examination of k′ showed the difference between Ks and Ks is negligible, i.e., the first equation usually reduces to the corresponding equation derived previously by assuming that the ambient vapor phase is saturated.
On the etherification reactions of polyoxymethylene hydrate with orthoesters
Authors: Okaya Takuji , Imada Takanobu , Matsubayashi Kanji 
Published: April 2003

AbstractThe etherification of polyoxymethylene hydrate with several orthoformates and orthobenzoates in the presence of LEWIS acids was studied. Reactivities of orthoesters were lowered as the alkoxy groups of orthoesters were higher. Intrinsic viscosities of polyoxymethylene decreased remarkably in the etherifications. The stabilities of orthoesters to LEWIS acids were also studied in connection with the reactivities in the etherifications. Methyl orthoester which showed high reactivity in the etherification decomposed catalytically in the presence of LEWIS acid. On the other hand, higher orthoesters whose reactivities were rather low did not decompose catalytically. The catalysts were assumed to be converted into less reactive compounds while catalyzing the etherification. The mechanism of etherification involving main chain scission of the polyoxymethylene is discussed.
The radiation induced reactions of aqueous polyethylene oxide solutions. II. Intrinsic viscosity changes in the pregel region
Authors: Stafford J. W. 
Published: April 2003

AbstractA model is proposed for the interpretation of molecular weight changes occurring in the pregel region of irradiated dilute aqueous polymeric systems. The model is, in principle, related to and gives results compatible with the molecular weight changes occurring during condensation polymerisation. On the basis of the above model and the ZIMM‐KILB theory of branching effects on intrinsic viscosity, calculated intrinsic viscosities agree satisfactorily with results for low molecular weight material only when allowance is made for intramolecular crosslinking and a drastic reduction in the rate of intermolecular crosslinking with dose for doses close to the gel dose. A similar quantitative approach is not possible for higher molecular weight material because of the high branching densities involved. A qualitative approach shows that many features of the radiation induced behaviour of intrinsic viscosities can be explained by the proposed model. For concentrations below the critical concentration, a treatment based on diffusion control of intermolecular crosslinking was found to be satisfactory.
The radiation induced reactions of aqueous polyethylene oxide solutions. V. Systems containing dioxane
Authors: Stafford J. W. 
Published: April 2003

AbstractThe radiation induced variations in intrinsic viscosity for concentrated aqueous solutions of polyethylene oxide containing relatively high proportions of dioxane show features which may be indicative of additive effect on water‐polymer interactions. In solutions more dilute in polymer and dioxane, the data can be treated in terms of competition between polymer and additive for hydrogen abstracting radicals and competition between dioxanyl radicals and the crosslinking process for macroradicals.
Free‐radical polymerization of methyl methacrylate in the presence of aluminium chloride
Authors: Bamford C. H. , Brumby S. 
Published: April 2003

AbstractA study has been made of the influence of chloride on the free‐radical polymerization of methyl methacrylate at 25°C; the reaction was photoinitiated (λ = 3650 Å) by azo‐bis‐isobutyronitrile or benzoyl peroxide. At a concentration of 0.18 mole · l−1, aluminium chloride increases the velocity coefficient of propagation by 70%, approximately, but the increase in the overall rate of polymerization is less than this on account of retardation. Transfer reactions are important in the presence of aluminium chloride, and it is likely that the observed retardation arises from low reactivity of transfer radicals in reinitiation. It is suggested that the transfer agent is a complex between methyl methacrylate and aluminium chloride.In our experiments aluminium chloride had no significant effect on the rate of initiation.
Préparation de gels réticulés par copolymérisation séquencée anionique du styrène avec le divinylbenzène
Authors: Weiss Par Paul , Hild Gérard , Herz Jean , Rempp Paul 
Published: April 2003

AbstractLa préparation de gels réticulés peut être effectuée par copolymérisation séquencée anionique de styrène et de divinylbenzène, sous l'action d'un promoteur bifonctionnel, en milieu aprotique et en atmosphère inerte. Les gels sont caractérisés par leur taux de gonflement maximum. La masse moléculaire moyenne du polystyrène «parent», la concentration globale de la solution, au moment de la réticulation, et la proportion de DVB mise en jeu constituent les trois paramètres qui déterminent la porosité et la structure même du gel. On peut donc préparer à volonté des réticulats homogènes de porosités très différentes.Dans un tel gel la distribution des tailles des mailles est fort étroite; la synérèse peut être aisément évitée; la signification physique du «point de gel» est bien établie. Ces trois propriétés de la réticulation anionique ne se retrouvent pas dans les gels préparés par voie radicalaire et justifient l'étude de ces gels.
Polymerization of epoxyorganosilanes. III. Copolymerization with glycidyl ether
Authors: Koinuma Hideomi , Inoue Shohei , Tsuruta Teiji 
Published: April 2003

AbstractGlycidyl ether with a trimethylsilyl group, i.e. (2.3‐epoxypropoxy)trimethylsilane was copolymerized cationically with alkyl glycidyl ethers by use of boron trifluoride etherate and triethylaluminum/water (1:0.5) system as catalysts. The results offered suggestions not only on the specific effect of the silicon substituent adjacent to the oxygen atom but also on the effect of substituents on the reactivities of glycidyl ethers in the cationic copolymerization.
Polymerizations initiated by boron fluoride etherate. Part I. Water co‐catalysis in the polymerization of styrene
Authors: Giusti P. , Andruzzi F. , Cerrai P. , Possanzini G. L. 
Published: April 2003

AbstractWater cocatalysis in the polymerization of styrene by boron fluoride etherate in ethylene and methylene dichloride has been studied at 25°C under vacuum.The results show clearly a strong cocatalytic effect by water on this polymerization. The curves relating the rate of polymerization to the ratio [H2O]/[BF3 · Et2O] for three different initial monomer concentrations present well defined maxima, whose height and position are approximately linear functions of the monomer concentration.The effects of water in experiments with successive additions of monomer and on molecular weight have been also investigated.The results are interpreted on the basis that the possible complexes of boron fluoride with water and diethyl ether have different catalytic activities.
Herstellung und eigenschaften gering vernetzter, noch löslicher copolymerer (mikrogele) aus styrol und bisacrylsäurephenylestern
Authors: Kämmerer Von Hermann , Mück Karl‐Friedrich 
Published: April 2003

AbstractDie radikalische, vernetzende Polymerisation von Mischungen aus Styrol und Bisacrylsäurephenylestern gab unter bestimmten Bedingungen in Toluol oder Dioxan lösliche Copolymere. Die photometrische Analyse der durch die Vernetzer zusätzlich eingebrachten Extinktionen im UV‐Gebiet zeigte das Zutreffen des BOUGUER‐LAMBERT‐BEERschen Gesetzes. Mittels der fraktionierenden Fällung wurde eine Reihe der erhaltenen Copolymeren in Fraktionen zerlegt. Die Fällungsfraktionierung erfolgte nach dem Molekulargewicht, wie osmotische Bestimmungen des Molekulargewichts zeigten. Je höher das Molekulargewicht der Fraktionen war, um so größer waren ihre STAUDINGERschen Indices ([η]‐Werte). Es konnte gezeigt werden, daß die Vernetzer in den Copolymeren statistisch covalent eingebaut waren.
Polycondensation of ω‐aminoalkylamino acid esters
Authors: Asahara Tomohiko 
Published: April 2003

Abstractω‐Aminoalkylamino acid esters of the following formula

were synthesized from diamines and methyl acrylate. Polycondensation at room temperature gave a highly crystalline oligo(amide amine), whereas an amorphous polymer was obtained by heating the monomer at elevated temperatures. The higher molecular weight polymer was obtained by thermal polycondensation of the crystalline oligomer. It was concluded that β‐fission of the chain partially occured by reversible MICHAEL reaction in the thermal polymerization. Kinetics of the polycondensation were also studied.
Anionic polymerization of aldehydes. II. Equilibrium polymerization of chloral
Authors: Mita Itaru , Imai Isao , Kambe Hirotaro 
Published: April 2003

AbstractAnionic polymerization of chloral at low temperature was found to be living and an equilibrium between polymerization and depolymerization was reached easily provided that the degree of polymerization of polychloral was not too high. True equilibrium monomer concentration and polymer yields were obtained only when an end‐capping reaction was carried out at the polymerization temperature because the non end‐capped living polymer was depolymerized immediately at room temperature. When the degree of polymerization of polychloral attained a certain critical value, polymerization did not proceed further due to occlusion of living ends and consequently a true equilibrium did not hold. From the temperature dependence of the equilibrium monomer concentration, the changes in enthalpy and entropy as well as the ceiling temperature for the polymerization of chloral in THF were determined as −3.5 kcal/mole, −12 cal/deg. mole and 11°C respectively.
Die herstellung einiger gekennzeichneter, aliphatischer azoverbindungen und ihre anwendung als initiatoren der polymerisation
Authors: Kämmerer Von H. , Sextro G. 
Published: April 2003

AbstractEs wird die Herstellung von vier Azoverbindungen beschrieben, die sich zum Teil vom α.α′‐Azo‐(isobuttersäurenitril) ableiten. Zwei Verbindungen geben bei der Polymerisation von Methacrylsäuremethylester und Styrol Endgruppen, die in den Polymeren photometrisch leicht zu bestimmen sind; für eine wird gezeigt, daß sie die Polymerisation von Styrol startet, ohne daß störende Nebenreaktionen auftreten. Die beiden anderen Azoverbindungen sind wegen ihrer hohen Zersetzungspunkte geeignet, radikalische Polymerisationen bei höheren Temperaturen auszulösen (160°C).
Viscosities of dilute solutions of poly (methyl methacrylate) and poly (ethyl methacrylate) in organic solvents
Authors: Vasudevan Padma , Santappa M. 
Published: April 2003

AbstractPoly(methyl methacrylate) and poly(ethyl methacrylate) prepared by a benzoylperoxide catalysed polymerization process were fractionated. The variation of the intrinsic viscosity and HUGGINS' constant with temperature, molecular weight and solvent was studied. From the viscosity data the thermodynamic interaction parameters χ, ψ, k etc., and the solubility parameter of the polymers were evaluated and discussed.
Polymere mit phosphor‐stickstoff‐bindungen1
Authors: Horn Von Hans‐Georg 
Published: April 2003

AbstractDie Synthese und Eigenschaften von 1.3‐Dimethyl‐2.4‐dithio‐2.4‐diazido‐1.3‐diaza‐2.4‐diphosphetidin werden beschrieben. Für die chemische Verschiebung dieser Verbindung werden −58,5 ppm gefunden. Für νas(NNN) findet man 2160 cm−1, für νsym(NNN) 1250 cm−1. Bei der Umsetzung dieses Azids mit Bis‐diphenylphosphino‐methan oder 1.2 Bis‐diphenylphosphino‐äthan werden Polymere mit Molekulargewichten bis zu 2600 erhalten. Die Polymeren zersetzen sich bei Temperaturen um 100°C.
Étude conductimetrique du système catalytique fluorure de bore‐éthérate/accepteurs π‐électroniques
Authors: Velichkova Par Roumyana S. , Panayotov Ivan M. 
Published: April 2003

AbstractThe effect of strong π‐electron acceptors on the ion equilibrium in the system boron fluoride‐diethyl etherate (BFE)/ethylene dichloride was investigated by means of conductivity measurements. The acceptors used were tetracyanoethylene (TCNE) and 1.3.5‐trinitrobenzene (TNB) in amounts commensurate with the catalyst concentration. In the solvent used BFE behaves as a weakly dissociated electrolyte with a dissociation constant of about 1.64·10−9 mole/l. The electron acceptors presented increase the equivalent conductance of the system. The dissociation constants in the presence of TNB and TCNE are 2.88·10−9 and 3.25·10−9 mole/l., respectively. Plots of log λ vs. log c for each of the systems show two straight parts with different slopes, which indicates a change in the electrolyte behaviour. This relative increase in conductivity with increasing concentration can be due to association between ion pairs and free ions.
Mechanical properties of polyacrylic acid in aqueous solution
Authors: Konno Akira , Kaneko Motozo 
Published: April 2003

AbstractThe pH and temperature dependence of the rigidity and the dynamic viscosity was observed for polyacrylic acid in aqueous solution. For sodium polyacrylate in aqueous solution, the effects of the concentration of the solution and of the amounts of added monovalent and divalent cations on the mechanical properties were measured at various temperatures. The rigidity for these solutions shows a maximum value at a certain pH or at particular temperature. The observed behavior may be explained by the proton or charge fluctuations between identical ionizable carboxyl groups.