bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Polymerization 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

OH‐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

Polysulphone, 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

The 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

L'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

Investigations 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

Die 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

Polymerization 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

The 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

The 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

A 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

The 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

A 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

La 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

Glycidyl 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

Water 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

Die 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

ω‐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

Anionic 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

Es 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

Poly(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

Die 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

The 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

The 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.
Polythiolester. II. Polythiolactid
Authors: Bührer Von Heinrich G. , Elias Hans‐Georg
Published: April 2003

Thiomilchsäure‐S‐carbonsäureanhydrid (4‐Methyl‐1.3‐oxathiolan‐2.5‐dion, 3‐Thia‐4‐methylbernsteinsäureanhydrid, TMSCA) wurde mit verschiedenen optischen Reinheitsgraden (D93L7, D50L50, D29L71) synthetisiert. Racemisches TMSCA besitzt einen Schmelzpunkt von 46°C, optisch reines (D‐ oder L‐)TMSCA einen von 62°C. TMSCA polymerisiert im festen Zustand (Sublimation, Umfällen). Primäre und sekundäre Amine sowie Wasser sind Polymerisationsinitiatoren; die Polymerisationsgeschwindigkeit ist aber in Dioxan‐Lösung sehr gering. Tertiäre Amine initiieren nicht. Optisch aktive Amine induzieren eine stereoselektive Polymerisation. D93L7‐Polythiolactid weist nach Messungen der optischen Rotationsdispersion in Chloroform keine Helixstruktur auf. (−)‐Dithiolactid wurde zu Vergleichsmessungen durch Pyrolyse von Polythiolactid synthetisiert.
The synthesis and properties of some aromatic polythioethers
Authors: Baron Arthur L. , Blank David R.
Published: April 2003

Polyarylene sulfides have been prepared from 4.4′‐biphenyldithiol and 4.4′‐biphenyl‐ether dithiol by reaction with 4.4′‐dichlorodiphenylsulfone. These polymers were oxidized to the corresponding polysulfoxides using hydrogen peroxide. The thermal properties of the polysulfoxides prepared were investigated and compared with those of their polythio‐ether precursors.
Reactivity of mono‐epoxides toward silk fibroin
Authors: Shiozaki Hideki , Tanaka Yoshio
Published: April 2003

The addition reaction of various mono‐epoxides such as epichlorohydrin, glycidol, allylglycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, propylene oxide, styrene oxide, hexadecene oxide, and vinyl cyclohexene monoepoxide with silk fibroin was investigated in the presence of some salts in different solvents at 30–80°C. Histidine, lysine, arginine, aspartic acid and glutamic acid, serine and tyrosine reacted. The weight gains decreased with increasing solubility parameter of the solvents, reached a minimum value at about 10 or at the solubility parameter of the epoxide, and then increased with the parameter. The salt effects on the epoxide‐silk reaction were described partly by the hydration ability or by the acidity of the cations, and also by the basicity or the nucleophilicity of the anions. The substituent effects of the epoxide on the add‐ons were elucidated by the modified TAFT equation, (log k − log k0)/σ* = ρp + ρsEs/σ*, where k0 and k are the rate constants for the reaction of a given compound and for the same reaction of one of its derivatives; σ* is the polar substituent constant characteristic of the substituent, Es is the steric substituent constant, and ρp and ρs are the reaction constants as measure of the susceptibility of the reaction to the polar and steric effects of substituents.
The hydrodynamic behaviour of amylose tricarbanilate in dilute solution. V. The estimation of the unperturbed dimensions of amylose tricarbanilate from measurements carried out in good solvents
Authors: Banks W. , Greenwood C. T.
Published: April 2003

Theories which separate short‐ and long‐range forces are applied to the experimental results for amylose tricarbanilate (ATC) in a good solvent (pyridine). The unperturbed dimensions obtained in this manner from light‐scattering, viscosity, and sedimentation measurements are compared with those obtained experimentally using a pyridine/water theta‐mixture. Satisfactory agreement is found when the FLORY‐OROFINO, or KRIGBAUM, treatment of the second virial coefficient is used, and also when the FIXMAN expression is applied to the measured coil dimensions. The apparent good agreement between the measured unperturbed dimensions and those obtained by means of the COWIE‐BYWATER treatment of the frictional coefficient is shown to be fallacious. Application of the STOCKMAYER‐FIXMAN treatment to viscosity measurements also leads to erroneous coil dimensions. Deviations from the hydrodynamic theories are shown to be due to the ATC macromolecule behaving as a partially free‐draining coil.

Basic criteria to be satisfied in order to determine the unperturbed coil dimensions of polymers from measurements made in a good solvent are suggested.
Solvent effects in radical copolymerization. I. Acrylamide
Authors: Saini Guido , Leoni Alvaro , Franco Simone
Published: April 2003

Acrylamide has been free radical copolymerized with styrene and methyl methacrylate at 70°C in different solvents (dioxane, dioxane/ethanol mixture, ethanol). A strong influence of the solvent on the copolymer compositions has been observed; particularly copolymers richer in acrylamide have always been obtained in dioxane.

These results indicate that the nature of the solvent (polarity, dielectric constant etc.) could affect the polarity and the reactivity of the acrylamide double bond as well as the stability of the growing radical. Other factors are also discussed.
Stereokontrolle. V. Radikalische Polymerisation von vinylformiat
Authors: Elias Hans‐Georg , Riva Marcello , Göldi Paul
Published: April 2003

Vinylformiat wurde in Substanz, Aceton, Chloroform bzw. Dimethylformamid bei Temperaturen zwischen +60 und −20°C radikalisch polymerisiert. Aus der Temperaturabhängigkeit des Verhältnisses Xi/Xs an isotaktischen und syndiotaktischen Diaden wurde die Differenz der Aktivierungsenthalpien (ΔHi≠ − ΔHs≠) bzw. ‐entropien (ΔSi≠ − ΔSs≠) für die Polymerisation in den einzelnen Lösungsmitteln berechnet. Zwischen (ΔHi≠ − ΔHs≠) und (ΔSi≠ − ΔSs≠) besteht ein Kompensationseffekt. Aus der Kompensationstemperatur T0 = 344°K der Stereokontrolle wird geschlossen, daß die Stereokontrolle mindestens teilweise durch Wasserstoffbrückenbindungen im übergangszustand bedingt ist.
Solvent effect in radical copolymerization. II. N.N‐dimethyl acrylamide
Authors: Saini Guido , Leoni Alvaro , Franco Simone
Published: April 2003

The free radical copolymerization of N.N‐dimethyl acrylamide with styrene or methyl methacrylate has been carried out at 70°C in solvents of different dielectricity constants. The present work does not show the strong solvent influence on copolymer compositions previously found for acrylamide copolymerizations. The influence of the presence of two alkyl groups on the amidic nitrogen is discussed. The calculated copolymerization parameters agree with the values obtained by other authors.
Bestimmung des Wechselwirkungsparameters χ und des Molekulargewichtes Mc an vernetzten Polymeren
Authors: Mula Angelo , Chinellato Luigi
Published: April 2003

Es wird eine Methode beschrieben, die die Bestimmung des Wechselwirkungsparameters Polymer‐Quellungsmittel χ und des Mol.‐Gew. Mc zwischen zwei Netzpunkten direkt an vernetzten Polymeren erlaubt.

Die Methode beruht auf Messungen der Drücke, die das vernetzte Polymere ausübt, wenn es in einem geschlossenen Volumen quillt.

Die Methode wird auf Naturkautschuk, Acrylnitril/Butadien/Styrol‐Copolymeres (ABS) und Polyurethan angewandt, und die Ergebnisse werden mit Literaturangaben verglichen.
Estimation of endgroups in poly(vinyl acetate) and the corresponding poly(vinyl alcohol) to study the hydrolysis reaction
Authors: Vidyarthi Dinesh K. , Mukhopadhyay Sailes , Palit Santi R.
Published: April 2003

The mode of branching in poly(vinyl acetate) has been studied using reverse dye partition (RDP) technique developed in this laboratory. It has been observed that during hydrolysis of poly(vinyl acetate) the degree of polymerization of the polymer decreases in all cases. This degradation is found to be erratic. It may be caused by the separation of branches which were connected to the main chain through ester linkage. This idea has been confirmed by the detection of average one carboxyl endgroup in the resulting shorter polymer chains.

The change in the number of endgroups in the parent and the corresponding hydrolysed polymer has been used as a tool for the estimation of number of branches in poly(vinyl acetate) molecules.
Zur Problematik der Endgruppenbestimmung nach Abbruch der Ziegler‐Natta‐Polymerisation mit Jod oder tritiiertem Alkohol. 10. Mitt. Zur Polymerisation mit metallorganischen Mischkatalysatoren
Authors: Schnecko H. , Jung K. A. , Grosse L.
Published: April 2003

Beim Abbruch der Polymerketten in heterogenen Ziegler‐Natta‐Systemen mit Jod zeigt sich, daß die Bestimmung der Jodendgruppen durch mikroanalytische Titration zu den gleichen Ergebnissen führt wie die Neutronenaktivierungsanalyse. Die J‐Bestimmung in Blindproben führt zu der Erkenntnis, daß die Temperaturabhängigkeit des Abbruches mit Jod und mit Alkohol ganz verschieden ist.

Für den an sich zu bevorzugenden Kettenabbruch mit tritiiertem Alkohol zeigt sich, daß die Bestimmung des scheinbaren Isotopeneffektes in jedem Fall erneut durchzuführen ist; dabei können ganz unterschiedliche Werte erreicht werden. Schließlich wird beim Abbruch mit tritiiertem Alkohol gefunden, daß die Metall‐Polymerbindungen bevorzugt reagieren und schon mit geringen Mengen an Abbruchreagenz vollständig abgebrochen werden.
Etude par diffusion de la lumière et par équilibre de sédimentation en gradient de densité de l'hétérogénéité en composition des copolymères statistiques
Authors: Lamprecht J. , Strazielle Cl. , Dayantis J. , Benoit H.
Published: April 2003

On a examiné le problème que pose la détermination expérimentale de la polydispersité en composition des copolymères statistiques azéotropes par les méthodes de la diffusion de la lumière et de l'équilibre de sédimentation en gradient de densité. Cette étude a été réalisée sur deux échantillons de copolymères statistiques styrène/méthacrylate de méthyle. On a montré en particulier que la méthode de la diffusion de la lumière reste valable pour déterminer les hétérogénéités en composition mais qu'elle présente certaines difficultés dans sa réalisation pratique.
Flüssige phasenpaare zur fraktionierung hochmolekularer polymethacrylsäureester
Authors: Tavel Peter V. , Bieri Vinzenz
Published: April 2003

Flüssige Phasenpaare zur Gegenstromfraktionierung hochmolekularer Polymethacrylsäureester (Mol.‐Gew. 60 000–600 000) nach dem Molekulargewicht und nach Estergruppen sind auf möglichst rationelle Weise gesucht worden. Als geeignet haben sich fast kritische Phasenpaare von Mehrkomponenten‐Systemen erwiesen. Sie bestehen aus einem Polymerlösungsmittel und zwei verschieden polaren Komponenten, die sich gegenseitig nicht mischen, wohl aber mit dem Polymerlösungsmittel. Eine 4. Lösungsmittelkomponente ist erforderlich, um für die multiplikative Verteilung günstige Verteilungskoeffizienten einzustellen oder das Polymere in die Gegenphase überzuführen. Sie entscheidet, in welcher Phase sich das Polymere anreichert, während der Abstand des Phasenpaares vom kritischen Punkt, gemessen am Phasendichteunterschied, die Größe des Verteilungskoeffizienten und die Lösungskapazität bestimmt. Für die Verteilung von Polymethacrylsäuremethyl‐und‐ äthylestern eignet sich das fast kritische System aus n‐Hexan/Aceton/Wasser. Der Methylester geht vollständig in die polarere, der äthylester in die unpolarere Phase. Bei Zugabe kleiner Mengen Benzol bzw. Essigsäure treten die Ester vollständig in die Gegenphase über. Diese Mengen sind vom Molekulargewicht des Polymeren unabhängig. Mit Phasenpaaren richtig eingestellter Zusammensetzung läßt sich ein Gemisch des Methyl‐ und äthylesters im Scheidetrichter durch 1–2 maliges Ausschütteln quantitativ trennen. Methyl/äthyl‐Mischester zeigen Verteilungskoeffizienten, die zwischen denjenigen der reinen Ester liegen. Die Phasenpaare sollten für die Fraktionierung von Mischestern nach ihrem Gehalt an Estergruppen geeignet sein. Hierzu sind aber besondere Verteilungszentrifugen erforderlich, die in Entwicklung begriffen sind.
Studies in addition polymerization in mixed solvent system part VI. Chain transfer of aromatic amines in the polymerization of methyl methacrylate
Authors: Bhattacharyya Bhupati Ranjan , Nandi Uma Shankar
Published: April 2003

Chain transfer constants of amines have been determined in the polymerization of methyl methacrylate using the mixed‐solvent method. The transfer constants are in the order of aniline < methyl aniline < dimethyl aniline. The chain transferring ability of amines has been explained in the light of the polar structure of the transition state. Substitution enhancing electron donating capacity of the amine nitrogen results in higher transferring ability. The decrease in the rate of polymerization due to amines, is in the same order as that of chain transferring capacity and is explained on the basis of hyperconjugation. The estimation of amino end group in the polymer by dye‐partition technique supports the mechanism suggested for transfer reaction of amines.
The role of oxygen in the oxidative polymerization of 2.6‐xylenol catalyzed by copper‐amine complexes
Authors: Tsuchida Eishun , Kaneko Masao , Nishide Hiroyuki
Published: April 2003

The role of oxygen in the oxidative polymerization of 2.6‐xylenol by copper‐amine complexes was studied. It was found that using an excess of a copper‐pyridine (Py) complex the polymerization proceeds even in the absence of oxygen, but that with an excess of a copper‐aliphatic amine (n‐butylamine or diethylamine) complex, oxygen is indispensable for the coupling to occur. It is concluded that oxygen promotes the electron transfer from the coordinated monomer to the metal ion or the dissociation reaction of the activated monomer, probably by forming a complex with the intermediate. Due to the π electron‐accepting property of the Py ring the Py‐copper complex is active even in the absence of oxygen. On the other hand, the aliphatic amine‐copper complex is active only when oxygen, which has an electron‐accepting ability, is coordinated. According to the kinetic equation derived on the basis of complex formation between oxygen and the catalyst, the reciprocal of the reaction rate constant (k2) is proportional to the reciprocal of the partial pressure of oxygen in the system; this is in agreement with the experimental results. The effect of the solvent (Py and o‐dichlorobenzene) is discussed.
Studies on homologous series of oligomeric antioxidants derived from p‐cresol/formaldehyde condensates. III. Evaluation in an ethylene/propylene copolymer
Authors: Huglin M. B. , Kay Edna , Knight G. J. , Wright W. W.
Published: April 2003

The effectiveness of compounds of the type
magnified image
as antioxidants in an ethylene/propylene (EP) copolymer has been examined and the results compared with those for some commercial high molecular weight antioxidants. Increasing the mol. wt. of the additive was found to improve its antioxidative efficiency and also to reduce the degree of interference with cure. Comparison with the results of earlier work1 showed that the efficiency of the antioxidants was affected by the nature of the polymer substrate.
Réaction de substitution nucléophile sur le polyméthacrylate de méthyle. I. Réaction du méthylsulfinyl sodium à température ambiante
Authors: Arranz F. , Galin J. C.
Published: April 2003

Nous avons étudié la réaction du méthylsulfinyl sodium (dimsylsodium) sur le polyméthacrylate de méthyle en solution homogène dans le diméthylsulfoxyde. A température ambiante et pour des degrés de substitution inférieurs à 30%, les réactions secondaires de cyclisation intramoléculaires sont négligeables; la substitution nucléophile s'effectue alors de façon sélective sur les groupements ester, sans dégradation ni réticulation, pour conduire avec des rendements quantitatifs à des copolymères binaires, homogènes en composition, porteurs de groupements latéraux céto‐β‐sulfoxyde, COCH2SOCH3, dont le méthylène activé présente une acidité assez élevée.

L'étude morphologique de ce copolymère en solution diluée dans le diméthylformamide montre que les dimensions non perturbées et le coefficient de rigidité de la chaǐne du copolymère demeurent voisins de ceux du polyméthacrylate de méthyle initial, mais que, par contre, les interactions polymère—solvant sont devenues bien plus intenses dans le cas du copolymère par suite des possibilités de solvatation spécifique des unités substituées céto‐β‐sulfoxyde.
Über die elementarprozesse bei der anionischen polymerisation des styrols in tetrahydropyran (THP)
Authors: Böhm L. L. , Schulz G. V.
Published: April 2003

Kinetische und konduktometrische Messungen am System Polystyrl‐Natrium in THP werden mit dem Ziel durchgeführt, alle in dem früher vorgeschlagenen dreiteiligen Reaktionsschema vorkommenden thermodynamischen und kinetischen Parameter zu bestimmen und mit den in anderen Lösungsmitteln gefundenen Werten zu vergleichen. Es zeigt sich, daß die Geschwindigkeitskonstanten der Monomeraddition an das Kontaktionenpaar, das solvatgetrennte Ionenpaar und das freie Anion, die sich um Größenordnungen unterscheiden, vom Lösungsmittel nur geringfügig beeinflußt werden. Der ungewöhnlich große Einfluß der Lösungsmittel auf die Polymerisationsgeschwindigkeit geschieht durch Verschiebung der Gleichgewichte zwischen den genannten Formen der Kohlenstoff‐Natriumbindung.
Studies on the mechanism of the ring opening polymerization of cycloolefins with particular reference to cycloolefin copolymerizations
Authors: Dall'Asta G.
Published: April 2003

The ring opening polymerization of cycloolefins in the presence of widely different transition metal catalysts leads to unsaturated polyalkenamers. The evolution of this reaction and of the catalysts is illustrated.

Cycloolefin copolymerizations have allowed to elucidate aspects concerning the site of ring opening for different catalysts and classes of cycloolefins. Further studies and observations refer to the transition state and to the stereochemistry of the cycloolefin coordination.

The comparison of the cycloolefin copolymerization and the cycloolefin insertion into preformed polyalkenamers allows deductions concerning the permanence of the catalytic centers.

Some properties of regular model polymers derived from hydrogenated poly(methylalkenamer)s are compared with those of the corresponding ethylene/propylene copolymers.
Aqueous polymerization of methacrylamide initiated by KMnO4/H2C2O4 redox system
Authors: Misra G. S. , Gupta C. V.
Published: April 2003

The polymerization of methacrylamide initiated by potassium permanganate/oxalic acid redox system has been studied at 35 ± 0.2°C in a nitrogen atmosphere. The rate of polymerization is independent of the activator (oxalic acid) concentration within the range 5·10−3 to 10·10−3 mole·1−1, except at very high (above 10·10−3 mole·1−1) or at very low (below 5·10−3 mole·1−1) concentrations of the activator. The rate varies linearly at low monomer concentration (up to 5.87·10−2 mole·1−1). The catalyst exponent decreases from nearly unity (0.91) to 0.66 with increase in concentration of the catalyst (KMnO4) probably due to participation of primary radicals in the termination of the growing chain. The addition of strong acid (H2SO4) within the range 5 · 10−4–15 · 10−4 mole · l−1, shows a constant pH of 2.7 resulting in no change in initial rate. With activator alone (H2C2O4 · 2H2O), within the pH range 2.7 to 2.9 an optimum is observed. The initial rate increases with increase in polymerization temperature. The overall energy of activation as calculated from the ARRHENIUS plot has been found to be 15.1 kcal · mole−1 within the temperature range 30–50°C.

Organic solvents (water miscible only) depress the initial rate and the maximum conversion. Small amounts of neutral salts (KCl and Na2SO4), however, show no appreciable effect on the polymerization rate, but small amounts of manganous salts (MnSO4) can increase the initial rate to a considerable extent. High concentrations of MnSO4 result in termination of the growing chain. A complexing agent, Na2F2, decreases the initial rate but increases the maximum conversion. Introduction of fresh catalyst at intermediate stages of polymerization increases both the rate of the reaction and the conversion.
Computer simulation of successively solutional fractionation of macromolecules
Authors: Kamide Kenji , Sugamiya Ken
Published: April 2003

The successive solution fractionation (SSF) (i.e., the successive solvent extraction of coacervate) was simulated by using an electronic computer. A polymer having the most probable distribution of number average degree of polymerization, X0n = 150, and weight average degree of polymerization, X0w = 300, was hypothetically fractionated, on the basis of the generalized FLORY‐HUGGINS‐FUJISHIRO theory in which the concentration dependence of the polymer/solvent interaction parameter, expressed as p, was taken into account. As p is increased the composition of the fraction with a larger degree of polymerization (X), obtained by SSF, decreased, while the smaller X region remained almost constant. The composition of the fraction in the region of the smaller X is much smaller than that obtained from successive precipitation fractionation (SPF). The fractionation data (Xw and the amount of the fraction) were analyzed according to the treatment of SCHULZ and of KAMIDE et al. The results revealed that the first one is preferable to the second one in the case of SSF. The broadness of the molecular weight distribution in the fraction markedly decreased with decrease in the initial concentration of polymer, v0p, if v0p was higher than 0.1%. An asymtotic, limiting value for Xw/Xn of an extremely small fraction of polymer, separated by SSF, was appreciably larger than that from SPF, but the corresponding value for the standard deviation was zero. The molecular weight distribution of the fractions becomes narrower as their amount is smaller. This behaviour is in contrast to the case of SPF. In SSF, a decreasing in the relative amount of each fraction, besides that of an initial concentration, effectively enables fractions of narrow distribution to be obtained.
The radical initiation of vinyl polymerization by α.α.α′.α′‐Tetrasubstituted dibenzyls
Authors: De Jongh H. A. P. , De Jonge C. R. H. I. , Huysmans W. G. B. , Sinnige H. J. M. , De Klein W. J. , Mijs W. J. , Jaspers H.
Published: April 2003

The radical polymerization of styrene, methyl methacrylate and acrylonitrile is initiated by α.α′‐dicyanodibenzyls α.α′‐disubstituted with ester, nitrile, amide or phenyl groups in the temperature range 60 to 100°C and by α.α.α′.α′‐tetracarboxymethyldibenzyl at 100 to 110°C. Vinylacetate and vinylchloride show a low reactivity.

The overall polymerization rate constants Kp have been determined dilatometrically for styrene initiated by a large number of dibenzyls and comparable peroxides. The styrene polymerization curves are generally comparable with those of peroxides. A notable exception is tetracyanodibenzyl.

The strong influence of α‐ and ring‐substituents in the dibenzyls on the styrene polymerization rate is discussed. The stereochemistry is also important : the meso α.α′‐dicyanodibenzyls α.α′‐disubstituted with ester groups give a 2.5 to 3.5 fold faster polymerization than their dl isomers.

The initiator efficiency is related to the kd values, determined from NMR line width measurements. The α.α′‐ dicyanodibenzyls α.α′‐disubstituted with ester groups are good initiators, while those with phenyl groups and nitrile groups are inefficient.

Relevant to initiation and termination, the 1.2‐addition of some of the dimers to styrene at 120 to 150°C has been studied with chemically induced dynamic nuclear polarization (CIDNP).
Versuche zur darstellung von azo‐polymeren durch photochemische polykondensation
Authors: Bössler Hanns Henning , Schulz Rolf C.
Published: April 2003

Es wurde versucht, die Photolyse von aromatischen Aziden zur Darstellung von Polymeren auszunutzen. Zu diesem Zweck wurden mehrere Bis‐Azide hergestellt und in verschiedenen Lösungsmitteln bestrahlt, wobei die berechnete Menge Stickstoff abgespalten wurde. Die meisten der tiefgefärbten Bestrahlungsprodukte sind unlöslich; bei bestimmten Ausgangsverbindungen konnten in Dichloressigsäure lösliche Anteile erhalten werden. Auf die Struktur der Bestrahlungsprodukte kann durch Vergleich der Spektren dieser Lösungen mit denen einer Modellverbindung geschlossen werden.
Über synthese und reaktionen mono‐und difunktioneller thiocarbonsäure‐trimethylsilylester
Authors: Kricheldorf Hans Rytger , Leppert Elmar
Published: April 2003

Durch Umsetzung von Carbonsäurechloriden oder ‐anhydriden mit Hexamethyldisilthian lassen sich Thiocarbonsäure‐trimethylsilylester (I und II) herstellen. Die Silylester I und II reagieren mit verschiedenen elektrophilen Reagenzien, z B. mit Säurechloriden und Alkylbromiden unter Eliminierung von Halogensilan, wobei stets Thiocarbonsäure‐S‐acyl‐oder ‐S‐alkylderivate entstehen. Aus α.ω‐Dithiocarbonsäure‐trimethylsilylestern (II) und den zugehörigen Dicarbonsäurechloriden wurden bisher noch nicht beschriebene Polyacylsulfide gewonnen; bei der Umsetzung mit Piperazin‐bis‐carbonylchlorid entstehen Polyamide (s. Summary).
Comparison of some statistic parameters of the most probable and the tung distributions with respect to the molecular heterogeneity
Authors: Sibiński Henryk
Published: April 2003

Some important parameters of the most probable and the TUNG distributions with respect to the molecular heterogeneity have been compared. Furthermore an interpretation method of the fractionation data has been given allowing to decide relatively simply and quickly whether the tested distribution is either of the most probable or the TUNG type.
Polymere aus Nitrilen. II. Einige Polykondensationsreaktionen des 2.5‐Diimino‐pyrrolidins, Imino‐pyrrolidons, Succinimids, 5‐Chlor‐2‐imino‐1‐pyrrolins und Bernsteinsäuredinitrils
Authors: Wöhrle D.
Published: April 2003

Erhitzen von 2.5‐Diimino‐pyrrolidin, Imino‐pyrrolidon oder 5‐Chlor‐2‐imino‐1‐pyrrolin in Substanz oder in hochsiedenden Lösungsmitteln führt in einer Polyselbstkondensation zum dunkel gefärbten Poly(1‐pyrrolin‐2‐yl‐5‐ylidennitrilo). Die Umsetzung von Bernsteinsäuredinitril, Succinimid oder 2.5‐Diimino‐pyrrolidin mit aromatischen Diaminen wie z. B. p‐Phenylendiamin ergibt in einer Polykondensationsreaktion dunkel gefärbte Polymere. Halbleitereigenschaften (σ300°K ∼10−8 bis 10−15 Ω−1cm−1) und thermische Analysen werden beschrieben.