bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation, copolymerization kinetics, and viscoelastic behavior of copolymers of 1,3‐butadiene and 1,4‐diphenyl‐1,3‐butadiene
Authors: Hsieh H. L. , Kraus Gerard 
Published: April 2003

Abstract1,4‐Diphenyl‐1,3‐butadiene reacts readily with sec‐butyllithium in toluene to form adducts. Although this 1,4‐substituted conjugated diene did not homopolymerize or copolymerize with styrene, with butadiene it formed copolymers having compositions varying from one end of the chain to the other. The monomer reactivity ratios found were r1 = 8.2, r2 = 0 in toluene and r1 = 2.1, r2 = 0 in toluene–tetrahydrofuran (0.2%) solution. The intramolecular composition distribution of these polymers varied from an initial butadiene‐rich composition, dependent on the ratio of monomers charged, to the equimolar composition of the alternating copolymer. In spite of this compositional heterogeneity, the crosslinked polymers exhibited a single glass transition characteristic of the mean composition. A secondary, high‐temperature dispersion observed in the dynamic viscoelastic properties of some of the products is shown to be attributable to network topological effects.
Sulfur‐containing polymers. VII. Alternating copolydisulfides
Authors: Kobayashi Norio , Fujisawa Tamotsu 
Published: April 2003

AbstractA variety of copolydisulfides have been synthesized in high yields by the fragmentation polymerization of bis(sulfenyl thiocarbonates) with dithiols in the presence of triethylamine. The structures of the copolymers were investigated by x‐ray and NMR studies. Alkylene–arylene copolydisulfides were alternating. Alkylene–arylene copolymers derived from arylene dithiols were alternating, and those prepared from alkylene dithiols were generally random. It was concluded that the present procedure makes it possible to prepare various kinds of alternating copolydisulfides by using appropriate combinations of a bis(sulfenyl thiocarbonate) and a dithiol.
Dichloromaleimide chemistry. IV. Preparation of poly(maleimide–ethers) from the reaction of bisdichloromaleimides with bisphenols
Authors: Relles H. M. , Schluenz R. W. 
Published: April 2003

AbstractA newly discovered reaction between phenols and dichloromaleimides has led to the synthesis of a new class of polymers of high molecular weight. These materials, represented by the general formula may be called poly(maleimide–ethers). Unlike polyimides,
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these materials are soluble in appropriate solvents and may be cast or compressionmolded into tough, flexible films.
Preparation and properties of polysulfonamideimides
Authors: Imai Yoshio , Okunoyama Hikaru 
Published: April 2003

AbstractA new class of polysulfonamideimide has been synthesized by the two‐step cyclopolycondensation of 4‐chlorosulfonylphthalic anhydride with aliphatic and aromatic diamines. The polycondensation‐addition reaction proceeded through the formation of poly(sulfonamideamide acids), and a subsequent thermal or chemical cyclodehydration of the precursor polymers yielded polysulfonamideimides. The poly(sulfonamide amide acids) having inherent viscosity in the range of 0.1–0.7 in dimethylacetamide were obtained in high yield. All of the polymers were soluble in polar aprotic solvents and in basic solvents. Aromatic polysulfonamideimide derived from bis(4‐aminophenyl) ether began to decompose at around 350°C in air as determined by differential thermal analysis and thermogravimetric analysis.
Solution decomposition of poly(vinylidene chloride): Effect of solvent and evolved HCl
Authors: Agostini D. E. , Gatzke A. L. 
Published: April 2003

AbstractThe effect of HCl on the rate of thermal decomposition of poly(vinylidene chloride) (PVDC) in nitrobenzene solution was measured with the object of determining the catalytic activity of HCl. Unlike those reports dealing with PVC decompositions, this study shows that in the absence of a cocatalyst, molecular HCl does not catalyze the decomposition of PVDC. In the presence of metals which can react with HCl to form Lewis acids (e.g., Fe0), a strong accelerating effect was observed. The uncatalyzed reaction shows a large rate increase with increasing polarity of the solvent, suggesting that in nitrobenzene the decomposition is mainly heterolytic in nature.
Cationic polymerization of α,β‐disubstituted olefins. Part 17. Effect of polymerization conditions on the reactivity of alkenyl ethers relative to vinyl ethers
Authors: Higashimura Toshinobu , Kawamura Kazumitsu , Masuda Toshio 
Published: April 2003

AbstractIn order to clarify the propagation reaction, vinyl ether was copolymerized with the corresponding alkenyl ether under various conditions. cis‐Propenyl ether (cis‐PE) was several times more reactive than trans‐PE and the corresponding vinyl ether in the copolymerization catalyzed by BF3 · O(C2H5)2 in toluene. However, the reactivity of cis‐PE relative to trans‐PE and the vinyl ether was found to be greatly decreased with increasing polarity of the solvent and to be very close to unity in such polar solvents as nitroethane. On the other hand, the reactivity of trans‐IBPE relative to IBVE was scarcely changed by polymerization conditions. Also, the nature of the initiator and polymerization temperature affect the reactivity of cis‐PE relative to the vinyl ether. These phenomena were explained by the relative stability of the bridged and open car bonium ions based on the polarity of the solvent and steric hindrance due to substituents in the trans isomer.
Polymerization of N‐vinylcarbazole in presence of carbon tetrabromide. III. Oxygen‐induced photodimerization in methanol solution
Authors: Kauffmann H. F. , Breitenbach J. W. , Olaj O. F. 
Published: April 2003

AbstractThe rate of photochemical dimerization of N‐vinylcarbazole (NVC) in methanol solution which takes place only in the presence of oxygen is greatly increased by addition of carbon tetrabromide (CTB). Similar high rates are obtained with sensitizers like benzil and biacetyl. The mechanism of formation of the cyclic dimer, trans‐1,2‐dicarbazole‐9‐yl‐cyclobutane (I), and of the open‐chain dimeric dimethoxy derivative, 1,4‐dicarbazole‐9‐yl‐1′,4′‐dimethoxy‐n‐butane (II), is discussed in some detail.
Polyamides from trans‐4‐octen‐1,8‐dioic and trans‐2‐trans‐6‐octadien‐1,8‐dioic acids
Authors: Lanzetta N. , Maglio G. , Marchetta C. , Palumbo R. 
Published: April 2003

AbstractNovel polyamides from trans‐4‐octen‐1,8‐dioic acid (4‐OD) and trans‐2‐trans‐6‐octadien‐1,8‐dioic acid (2,6‐ODD) ad linear aliphatic diamines or piperazine were prepared in good yields by low‐temperature polycondensation. The polymers obtained were investigated by infrared spectroscopy, x‐ray diffraction, and differential scanning calorimetry. Polyamides from 4‐OD show high molecular weights and crystallinities and Tm above 500°K, whereas those from 2,6‐ODD are very weakly crystalline and decompose without melting in nitrogen at temperatures higher than 550°K. DSC studies revealed in the case of 4‐OD polymers with odd diamines, a multiple peak phenomenon in the melting region, strongly dependent from the heating rate. Some hypotheses consistent with this behavior are briefly discussed, and it is concluded that the phenomenon arises from melt recrystallization occurring during the DSC scan.
Radiation‐induced polymerization of glass‐forming systems. IV. Effect of the homogeneity of polymerization phase and polymer concentration on temperature dependence of initial polymerization rate
Authors: Kaetsu Isao , Ito Akihiko , Hayashi Koichiro 
Published: April 2003

AbstractThe effect of homogeneity of polymerization phase and monomer concentration on the temperature dependence of initial polymerization rate was studied in the radiation‐induced radical polymerization of binary systems consisting of glass‐forming monomer and solvent. In the polymerization of a completely homogeneous system such as HEMA–propylene glycol, a maximum and a minimum in polymerization rates as a function of temperature, characteristic of the polymerization in glass‐forming systems, were observed for all monomer concentrations. However, in the heterogeneous polymerization systems such as HEMA–triacetin and HEMA–isoamyl acetate, maximum and minimum rates were observed in monomer‐rich compositions but not at low monomer concentrations. Furthermore, in the HEMA–dioctyl phthalate polymerization system, which is extremely heterogeneous, no maximum and minimum rates were observed at any monomer concentration. The effect of conversion on the temperature dependence of polymerization rate in homogeneous bulk polymerization of HEMA and GMA was investigated. Maximum and minimum rates were observed clearly in conversions less than 10% in the case of HEMA and less than 50% in the case of GMA, but the maximum and minimum changed to a mere inflection in the curve at higher conversions. A similar effect of polymer concentration on the temperature dependence of polymerization rate in the GMA–poly(methyl methacrylate) system were also observed. It is deduced that the change in temperature dependence of polymerization rate is attributed to the decrease in contribution of mutual termination reaction of growing chain radicals to the polymerization rate.
Copolymerization of 1,6‐anhydroglucose and 1,6‐anhydromaltose derivatives
Authors: Lindenberger William H. , Schuerch Conrad 
Published: April 2003

AbstractThe copolymerization of 1,6‐anhydro‐2,3,4‐tri‐O‐(p‐methyl‐benzyl)‐β‐D‐glucopyrnose [TXGL, M1] with 1,6‐anhydro‐2,3‐di‐O‐benzyl‐4‐O‐(2,3,4,6‐tetra‐O‐benzyl‐α‐D‐glucopyranosyl)‐β‐D‐glucopyranose [HBMA, M2] has been studied as a method of producing dextrans of controlled composition with a linear backbone and randomly distributed single glucose units as side chains. Copolymers of intrinsic viscosities ranging from 0.51 to 0.05 dl/g are produced. The copolymerization appears to follow classical copolymerization theory but is affected adversely by the low reactivity of the maltose derivative. Reactivity ratios have been calculated for runs catalyzed by 10 mole‐% and 20 mole‐% phosphorus pentafluoride (PF5): r1 = 1.91 ± 0.35, r2 = 0.28 ± 0.25 and r1 = 2.21 ± 0.15, r2 = 0.21 ± 0.10, respectively.
Cationic copolymerization of 2‐vinyl‐1,3‐dioxane with styrene and 1,3‐dioxolane
Authors: Okada Masahiko , Uno Masaaki , Sumitomo Hiroshi 
Published: April 2003

AbstractCopolymerization of 2‐vinyl‐1,3‐dioxane with styrene and 1,3‐dioxolane was carried out in methylene chloride at 0°C with triethyloxonium tetrafluoroborate as an initiator. Random copolymers were obtained from both of these monomer pairs, but attempted copolymerization of 2‐vinyl‐1,3‐dioxane with 3,3‐bis(chloromethyl)oxetane under similar conditions resulted in the homopolymer of the latter monomer. There were three structural units of 2‐vinyl‐1,3‐dioxane in these copolymers as in its homopolymer: the “ester” unit, which was formed by vinyl addition with hydride shift followed by ring‐opening rearrangement, the “vinyl” unit produced by ring‐opening reaction, and the unit with a pendant 1,3‐dioxane ring formed by simple vinyl addition. The fractions of the ester and vinyl units to the total 2‐vinyl‐1,3‐dioxane units in the copolymer of 2‐vinyl‐1,3‐dioxane with styrene decreased with decreasing 2‐vinyl‐1,3‐dioxane content. On the contrary, the fraction of the vinyl unit in the copolymer of 2‐vinyl‐1,3‐dioxane with 1,3‐dioxolane increased slightly with decreasing 2‐vinyl‐1,3‐dioxane content, while that of the ester unit decreased. The reactivities of the propagating species are discussed on the basis of these results.
Anionic copolymerization of isocyanates with ketenes
Authors: Dyer Elizabeth , Sincich Eugene 
Published: April 2003

AbstractDiphenyl‐, phenylethyl, and phenylmethylketene have been copolymerized with phenyl isocyanate by use of sodium naphthalene in dimethylformamide (DMF) at −45°C. Reactivity ratios of phenyl isocyanate (r2) with diphenylketene (r1) were r1 = 0.10, r2 = 0.29; with phenylethylketene (r1) were r1 = 1.6, r2 = 0.10; and with phenyl methyl ketene (r1) were r1 = 4.8, r2 = 0.02. The same initiator and solvent system were used for homopolymerization of phenylethylketene and copolymerization with m‐chloro‐, p‐chloro‐, p‐methoxy‐, and m‐methoxyphenyl isocyanate as well as with phenyl isocyanate. Molecular weights ranged from 1740 to 4000. The effect of substituents on the order of isocyanate incorporation into the copolymer was m‐Cl = p‐Cl > m‐MeO > H > p‐MeO. Phenylethylketene was also copolymerized with m‐methoxyphenyl, p‐methoxyphenyl, and p‐tolyl isocyanate in tetrahydrofuran (THF) at −78°C. Molecular weights ranged from 2800 to 10,500. The least reactive isocyanate was incorporated into the copolymer to a greater extent in this solvent than in the more polar DMF. DTA showed the presence of crystallinity only in polymers of high isocyanate content. The ketenes copolymerized less readily with alkyl isocyanates, such as ethyl, n‐butyl, n‐hexyl, and cyclohexyl isocyanate, than with the aromatic isocyanates when sodium naphthalene was used in either DMF or THF.
Synthesis of block copolymer with polystyrene and nylon units
Authors: Shimura Yukio , Ikeda Noboru 
Published: April 2003

AbstractBis‐ε‐aminocaproylaminocaproylhexamethylenediamine (I) was synthesized as an analog of 6‐nylon pentamer diamine, and its incorporation into block copolymers was studied with the use of α,ω‐dihydroxyl, α,ω‐bisdimethylchlorosilyl, and α,ω‐diepoxy polystyrene. In the course of the experiments, the stability and the reactivity of 4,4′‐diphenylmethane diisocyanate and tetramethylene diisocyanate in aprotic dipolar solvents were examined by infrared spectroscopy. The only usable solvent, N‐methylpyrrolidone, was found still inadequate for the synthesis involving I, diisocyanate, and α,ω‐dihydroxyl polystyrene. A block copolymer having Mn = 18,000 was obtained by the reaction of I and α,ω‐diepoxy polystyrene. All Tg values of the block copolymers were above 90°C, higher than for polystyrenes with corresponding molecular weight.
Alternating copolymer of styrene–acrylonitrile obtained with vanadium‐based complex catalyst in presence of monomers
Authors: Deshpande A. B. , Rajan C. R. , Kapur S. L. 
Published: April 2003

AbstractVanadium‐based catalyst complexes prepared in the presence of monomers have been used for the copolymerization of styrene and acrylonitrile. VOCl3–Al(i‐C4H9)3 catalyst system seems to yield an alternating copolymer. The copolymers are easily soluble in DMF and have low softening points.
Semiconducting polymers based on charge‐transfer complexes. II. Crystal structure of poly‐N‐4‐[4‐(methylthio)phenoxy]butyrylethylenimine
Authors: Summers James W. , Litt Morton H. 
Published: April 2003

AbstractOf the two electron‐donor‐containing polymers whose synthesis was described in Part I of this series, one was crystalline. This polymer, which contains (methylthio)phenoxy electron‐donating groups on the side chains of an N‐acyl‐substituted polyethylenimine, could be indexed in a triclinic unit cell of dimensions a = 4.35 Å, b = 24.0 Å, c = 12.7 Å, and α = β = γ = 90°. The polymer has the side chains alternating on each side of the polymer backbone. They extend to form at 24.0 Å repeat in that direction. The thickness of the ribbonlike molecule is 4.35 Å, while the repeat distance along the polymer backbone is 12.7 Å, which includes four monomer units.
Stereospecific polymerization of acetaldehyde by R2AlOR′ catalyst
Authors: Yasuda H. , Fujita K. , Yamamoto S. , Tani H. 
Published: April 2003

AbstractStereospecific polymerization of acetaldehyde was examined by using four possible purified diethylaluminum butoxides, (Et2AlOBu)2 [Bu = n‐, i‐, sec‐, or tert‐Bu], as catalyst. These catalysts gave isotactic polyacetaldehyde quantitatively irrespective of the degree of branching of the butyl group, only when an optimum amount of water (about 0.03 mole/mole of catalyst) was added to the purified acetaldehyde monomer. Quite similar results were obtained for organozinc catalysts. These results indicate that water is an indispensable cocatalyst in the polymerization reaction with organoaluminum and zinc catalysts. An novel coordinate cationic mechanism was proposed for the stereospecific polymerization of acetaldehyde with organoaluminums, based on the above phenomena and on the inactivation of the catalyst by forming a complex with a strong Lewis base.
Characterization of networks from the peroxide cure of polybutadiene. II. Kinetics and sol–gel
Authors: Hergenrother William L. 
Published: April 2003

AbstractThe kinetics of cure of polybutadiene with molecular weights varying from 12,500 to 92,000 g/mole and containing 23–93% of 1,2 microstructure were investigated at two levels of dicumyl peroxide and two temperatures. The relative rates of termination were determined as a function of vinyl content and of reactive additives. Sol‐gel measurements showed that molecular weights between crosslinks of less than 100 g/mole could be obtained. Network formation was found to be a polymerization process in which each free radical formed started only one crosslink chain. However, at high initiator levels chain scission did occur during cure.
Thermal degradation of poly(vinyl chloride). II. Degradation mechanism based on decomposition energetics
Authors: Gupta V. P. , St. Pierre L. E. 
Published: April 2003

AbstractOn the basis of the measured activation energies for radical and HCl generation in four poly(vinyl chlorides) of controlled structures, an overall mechanism of degradation is proposed. The mechanism is a chain reaction involving a β‐chloro elimination from a radical‐containing polymer molecule. Molecules containing tertiary CCl bonds are shown to undergo a fast initiation. Those containing tertiary CH bonds are also demonstrated to be highly unstable, but the instability is not associated with the initiation step.
Evaluation of mass transfer rate during Ziegler‐Natta propylene polymerization
Authors: Keii Tominaga , Doi Yoshiharu , Kobayashi Hiromu 
Published: April 2003

AbstractMass transfer which affects the rate of propylene polymerization with titanium trichloride–triethylaluminum, has been evaluated by use of a new method developed for this heterogeneous reaction. The polymerization was carried out with the usual flask reactor equipped with a paddle stirrer; the rate of gas absorption into the polymerization slurry was proportional to stirring speed and the reciprocal of the total amount of polymers produced. It has been confirmed that the polymerization rate separated from the absorption rate is purely kinetic (propagation), and an effective physical process, such as monomer transfer through a polymer film covering the catalyst surface, no longer exists.
Polymerization of vinyl chloride in the presence of precipitants. II.
Authors: Arita Koichiro , Stannett V. T. 
Published: April 2003

AbstractThe kinetics of the radiation‐induced polymerization of vinyl chloride in the presence of precipitants has been successfully described by a one‐parameter equation as follows,

where ϕ0 is initial monomer volume fraction, X is conversion, t is time, and k is reaction constant. The equation was confirmed for extensive conditions of temperatures and monomer concentrations in the case of polymerization in methanol. The degree of polymerization was related with the reaction constant k, initial monomer volume fraction ϕ0, monomer chain transfer constant Cm, conversion X, and the initiation rate I as follows,

The factors which determine the value of the reaction constant k were elucidated through measurements of the reaction constant k and the degree of polymerization DPn.
Thermomechanical behavior of a polyphenylimide‐quinoxaline
Authors: Augl Joseph M. , Booth Hubert J. 
Published: April 2003

AbstractLinear polyphenylimide‐quinoxalines (PPIQ) can be crosslinked by isothermal heat treatment in an inert atmosphere. To show this, three polyphenylimide‐quinoxalines were prepared which differed only in molecular weight and polymer chain endings. Apparent activation energies of thermal crosslinking were then obtained from the rates of change of Tg as a function of time and temperature. The values (60 kcal/mole) were essentially the same as those for the thermal degradation of the same polymer in vacuum. Differences in polymer molecular weight had a distinct effect on the rates of change of Tg but the polymer chain ends seemed to have a lesser effect than previously observed on polyphenylquinoxalines (PPQ). Nevertheless, the rate of change in Tg is greater for PPIQ than for PPQ of a similar molecular weight. This indicates that the imide portion of the polymer chain leads to faster crosslinking under isothermal conditions.
Crystallization‐induced reactions of copolymers. I. Ring‐size isomerization of poly(ester acetals)
Authors: Lenz R. W. , Martin E. , Schuler A. N. 
Published: April 2003

AbstractThe isomerization reactions of five‐ and six‐membered acetal rings in copolyesters containing these structures along the backbone were studied both in the melt and in the semicrystalline solid state. For the latter, isomerization of the solid copolymer at a temperature well below the melting point was in a direction opposite to that expected from the data for the acetal ring equilibration in a homogeneous melt. This apparent anti‐equilibrium behavior was rationalized on the basis of the continuous removal of the five‐membered ring units by crystallization during the reaction, thereby forcing the reaction in the direction controlled by the ability of that unit to crystallize, irrespective of the normal thermodynamic properties of the reaction itself. The probable requirements to be met for the operation of this type of crystallization‐induced reaction are discussed.
Stereostructure of oligomeric polyisoprenyllithium in tetrahydrofuran
Authors: Lachance P. , Worsfold D. J. 
Published: April 2003

AbstractThe oligomer of polyisoprenyllithium, 2,5,5‐trimethylhexen‐2‐yllithium, formed from tert‐butyllithium and one molecule of isoprene in benzene has a structure similar to that of higher members of the series and also similar properties. In THF only one stereoisomer is stable, and an attempt is made to determine its stereostructure. The lithium compound was converted at low temperature to the acid, and this by a series of steps in which the structure was monitored to the acid's parent hydrocarbon 3,6,6‐trimethyl‐3‐heptene. This was then compared with a synthesized sample of this hydrocarbon of known structure. In this way it was shown that the original lithium compound had a cis configuration in tetrahydrofuran solution.
Photocopolymerization of methacryloyl‐L‐valine methyl ester with maleic anhydride
Authors: Nishihara Koji , Suzuoka Akihiro , Sakota Naokazu 
Published: April 2003

AbstractMethacryloyl‐L‐valine methyl ester (MAVM) and maleic anhydride (MAn) were photopolymerized without initiator in dioxane at 35°C. Copolymer having a 1:1 molar ratio of the monomers was obtained regardless of both molar ratio of monomers in the feed and polymerization time. The circular dichroism (CD) spectrum of the copolymer before and after hydrolysis showed the induction of asymmetric centers into the polymer main chain. Spectroscopic and kinetic studies suggested the alternating and stereoregular copolymerization of MAVM and MAn, in which a charge transfer complex with a 1:1 molar ratio of monomers participated.