bluuebunny/crossref_metadata_2025_split huggingface dataset:
Room temperature polymerization of glycidol
Authors: Sandler Stanley R. , Berg Florence R. 
Published: April 2003

AbstractGlycidol has been shown to be easily polymerized at room temperature in the presence of triethylamine, pyridine, lithium hydroxide, potassium hydroxide, sodium hydroxide, sodium methoxide, sodium amide, and other catalysts. Its reactivity with these catalysts is vastly greater than that of propylene oxide. Evidence is presented to support the structural assignment for polyglycidol and the mechanism of polymerization.
Radiation‐induced solid‐state copolymerization of maleic anhydride and acenaphthylene
Authors: Shimizu Akira , Hayashi Koichiro 
Published: April 2003

AbstractRadiation‐induced solid‐state copolymerization of the maleic anhydride–acenaphthylene system was carried out for the purpose of studying the solid‐state polymerization of vinyl compounds in a binary system. Melting point measurement confirmed that this binary monomer system forms a eutectic mixture in the solid state. The solid‐state polymerization of these monomers proceeds at maximum rate at the eutectic composition, and the polymerization products consist of a mixture of polyacenaphthylene and 1:1 maleic anhydride–acenaphthylene alternating copolymer. Since the 1:1 copolymer was obtained in solution polymerization also and maleic anhydride did not homopolymerize in solid state, it is considered that the solid‐state copolymerization of maleic anhydride and acenaphthylene occurs in a liquidlike state at the boundary of the two monomer crystals.
Isomorphism in copolyamides of long repeating chain units containing oxa‐ and thia‐alkylene linkages
Authors: Saotome Kazuo , Komoto Hiroshi 
Published: April 2003

AbstractVarious copolyamides of long repeating chain units were prepared from hexamethylenediamine (HMDA) and p‐xylylenediamine (PXDA) with aliphatic dicarboxylic acids of three structural types: α,ω‐alkanedioic, α,ω‐oxaalkanedioic, and α,ω‐thiaalkanedioic acids. Both binary and ternary combinations of these dicarboxylic acids having the same number of chain atoms with the diamine afforded highly crystalline copolyamides. In all cases of these copolymers, the plots of the melting points versus the compositions are expressed by linear relations, even in the ternary systems. For example, the melting points of the copolyamides of HMDA with 6‐oxaundecanedioic and 6‐thiaundecanedioic acids are practically unchanged in all ranges of composition. The same relation is also observed in the corresponding copolyamides of PXDA. The relation between the densities and the composition is plotted with good linearity in every case. From x‐ray examination, the lattice spacings of each copolyamide are ascertained to be unchanged by the composition. These results reveal that methylene, ether, and thioether linkages are in the relation of isomorphous replacements for each other in these copolyamide systems. Moreover, the linear relationship between the melting point and the composition is explained by assuming that the entropy of fusion in these copolyamides changes linearly according to the change of the composition.
Polymerization of butene‐2 with isomerization to butene‐1
Authors: Otsu Takayuki , Shimizu Akihiko , Imoto Minoru 
Published: April 2003

AbstractAn attempt has been made to prepare a high molecular weight isotactic polybutene‐1 from cis‐ or trans‐butene‐2. Polymerization of butene‐2 did not occur due to the steric effect of the substituents. In the presence of TiCl3–Al(C2H5)3 catalyst, however, both butene‐2 monomers were found to polymerize at a slower rate than butene‐1 and to give polymers consisting of the repeating unit of butene‐1. From the gas chromatographic determination of the isomer distribution of the butenes recovered after the polymerization, it was found that the butenes isomerized, in the presence of the catalyst system containing TiCl3, to approach the thermodynamic equilibrium mixture of butene‐1, cis‐butene‐2, and trans‐butene‐2. It was also found that the rates of polymerization of butene‐2 for the catalyst systems used were proportional to the isomerization rates. These results show that butene‐2 isomerizes first to butene‐1 which has less steric hindrance and then polymerizes as butene‐1, through ordinary vinyl polymerization by a coordinated anionic mechanism. This type of polymerization was observed in some other linear β‐olefins such as n‐pentene‐2 and n‐hexene‐2.
Studies on Ziegler‐Natta catalysts. Part III. Composition of the nonvolatile product of the reaction between titanium trichloride and trimethylaluminum or dimethylaluminum chloride
Authors: van Looy H. M. , Rodriguez L. A. M. , Gabant J. A. 
Published: April 2003

AbstractThe surface product formed in the reaction between TiCl3 and Al(CH3)3 has been studied. Stoichiometric data, CH3/CD3 exchange, and infrared spectra permit the conclusion that the surface product is essentially a compound having the formula
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A model structure is proposed for this compound, valid for the 001 face of α‐TiCl3. In it the titanium and chlorine atoms maintain the positions which they occupy in the α‐TiCl3 lattice. One of the methyl groups protrudes from the surface whereas the other occupies the chlorine vacancy created during the reaction in the chlorine surface layer. A different sterism of the methyl groups is compatible with the experimental result that half of the methyl groups are very easily exchanged whereas the other half are not touched by the exchanging agent. According to this model it has to be assumed that the titanium atoms in the 001 plane, by far the largest face of the α‐TiCl3 crystal, are not accessible. A similar model, loading to equivalence conclusions is proposed for β‐TiCl3. The infrared spectra of Al(CH3)3, Al(CD3)3, AlCl(CH3)2, AlCl(CD3)2, AlCl2CH3, AlCl2CD3, TiCl3CH3, TiCl3CD3, Hg(CD3)2, and Zn(CD3)2 are discussed. Spectra of surface products formed on interaction of some of these compounds with TiCl3 are given.
Polymers from vinyl esters of perhydrogenated rosin
Authors: Liepins R. , Marvel C. S. 
Published: April 2003

AbstractVinyl esters of tetrahydro acids from perhydrogenated rosin have been homopolymerized; copolymerized with vinyl chloride, vinyl acetate, butadiene; and terpolymerized with styrene and acrylonitrile. Materials containing such vinyl esters of tetrahydro acids can be readily crosslinked with peroxide.
Anionic copolymerization of styrene and 1,1‐diphenylethylene
Authors: Ureta E. , Smid J. , Szwarc M. 
Published: April 2003

AbstractKinetics of anionic copolymerization of styrene (S) and 1,1‐diphenylethylene (D) were investigated in THF. The rate constant of addition of D to living polystyrene was found to be k1,2 ± = 250 l./mole‐sec. for , Na+ ion‐pair, and that for the free , Na+ ion is k1,2−∼400,000 l./mole‐sec. Both values refer to 25°C. The addition of styrene to D−, Na+ was found to be reversible:
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and k2,1 was determined by three different methods to be ∼0.5–0.7 l./mole‐sec. Studies performed in a stirred‐flow reactor led to k‐21 = 13 sec. −1 and K21 ∼ 5 × 10−2 l./mole. An alternating copolymer is obtained in the presence of a large excess of 1,1‐diphenylethylene.
Polyelectrolytic character of amylose. I.
Authors: Doppert H. L. , Staverman A. J. 
Published: April 2003

AbstractElectrophoresis and titration experiments on amylose solutions and gels are described. The experimental results clearly demonstrate the negative charge of the amylose molecules at pH values of 11 and higher. With the assumption that a monomer unit can carry one charge only, pK's of amylose are calculated. The agreement between the pK's of amylose and glucose forms an indication that hydroxyl groups dissociate in the above‐mentioned pH range.
Cyclo‐ and cyclized diene polymers. XII. Cationic polymerization of isoprene
Authors: Gaylord N. G. , Matyska B. , Mach K. , Vodehnal J. 
Published: April 2003

AbstractPolymerization of isoprene with Lewis acids in n‐heptane is a process leading to a quasiequilibrium which is characterized by very low conversions. Polymerization rates in aromatic solvents are much higher due to extensive chain transfer with solvent with regeneration of the original active centers. The rate of monomer disappearance in benzene or toluene when aluminum bromide is the catalyst is second order with respect to monomer concentration. The reaction order with respect to the catalyst depends on the reaction conditions; at constant monomer concentration it is approximately one. Polymerization rates in halogenated solvents with the use of syringe techniques are much higher than those in aromatic solvents. Polymers obtained with various cationic catalysts ranged from oils to white powders having molecular weights up to more than 100,000 depending on reaction conditions. All polymers exhibited infrared spectra characteristic of cyclopolydienes, and the content of linear structures usually did not exceed 20%, irrespective of the nature of the catalyst or solvent. In solvents of higher polarity, such as o‐dichlorobenzene, more linear structures were detected. Among residual linear forms the trans‐1,4 addition was found to prevail. Residual unsaturation in polymers did not exceed 30%.
Kinetic study of heterogeneous polymerizations of styrene and/or β,β‐d2‐styrene by Ziegler‐Natta catalysis
Authors: Simon A. , Jarovitzky P. A. , Overberger C. G. 
Published: April 2003

AbstractSubstantial concentrations of tetravalent titanium have been shown to exist in a TiCl4—Al(C2H5)3—benzene catalytic system for catalyst aging times ≥ 20 min. at 60°C. Substitution of β,β‐d2‐styrene for styrene with the above catalysic system appears to have no effect on either rate of polymerization or product intrinsic viscosities. These phenomena support a mechanism of chain propagation and termination as suggested earlier.
ESR study of free radicals formed by γ‐irradiation of poly(ethylene terephthalate)
Authors: Campbell D. , Araki K. , Turner D. T. 
Published: April 2003

AbstractFree radicals formed by γ‐irradiation of oriented samples of poly(ethylene terephthalate) (PET) were studied at 25°C. by ESR spectroscopy. The G value for trapped free radicals is 0.02. The predominant radical is identified as $\text{O} - \text{\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{C} H} - \text{CH}_\text{2} - \text{O} -$, and a minor component of the spectrum is tentatively assigned to the radical COĊ6H3CO. The absence of cyclohexadienyl type radicals is discussed. Previously reported dose rate effects in PET are explained by reference to a chain reaction involving β‐bond scission of the radical $\text{O} - \text{\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{C} H} - \text{CH}_\text{2} - \text{O} -$.
Alternation Tendency in Copolymerization
Authors: Tada Koichi , Fueno Takayuki , Furukawa Junji 
Published: April 2003

AbstractThe number fractions of the alternate diads and triads and the average length of the alternate sequence may be used as the indices of the alternation tendency of binary copolymerizations. It is shown that these indices take on maximum values when the monomer feed ratio is such that [M1]/[M2] = (r2/r1)1/2. The physical significance of the customary measure of the alternation tendency r1r2 is discussed.
Elastic properties and network structure in silicone gum vulcanizates
Authors: Bobear W. J. 
Published: April 2003

AbstractA model of a rubber network formed from finite, linear polymer chains is treated, using expressions from accepted elastic theory as well as relationships that have been less generally used or only implied. The resultant empirical mathematical expressions conform very closely to the predictions of the simple kinetic theory of rubber elasticity and are mathematically consistent, in that the major properties and measurements are interrelated, and apparent inconsistencies in the literature are reconciled. As a consequence, an empirical equation is developed for the relationship between elastic properties and network structure in silicone gum vulcanizates. This equation is then applied to the estimation of peroxide crosslinking efficiencies.
Kinetic and equilibrium phenomena in the system: Acetone vapor and polycarbonate film
Authors: Kambour R. P. , Karasz F. E. , Daane J. H. 
Published: April 2003

AbstractAmorphous films of Lexan polycarbonate have been exposed to acetone vapor at controlled temperatures and partial pressures in order to study sorption kinetics and thermodynamics and polymer crystallization behavior. Sorption isotherms show a discontinuity is slope at or near the depressed glass transition, which itself was identified by torsion pendulum measurements. Crystallization abruptly begins to occur at partial pressures equal to or slightly above that of the solubility transition and is manifested by delayed desorption and whitening phenomena. In this process 20% crystallinity is usually developed, as measured by calorimetry which, however, produces a 40% drop in acetone solubility. Although the depressed glass temperature is near 0°C. in saturated atmospheres—a drop of 145°C.—the melting point is only depressed 60 or 70°C. Such disparity probably accounts for the enhanced polycarbonate crystallization rate in acetone over that in the dry bulk polymer above the normal Tg.
Relaxation phenomena in concentrated polyelectrolyte solution. II
Authors: Nishida Noboru 
Published: April 2003

AbstractDynamic viscoelastic properties of 10 and 20% aqueous solutions of sodium polyacrylate were studied by the electromagnetic transducer method at 500 cps in the temperature range of 0–50°C. These solutions distinctly showed a relaxation phenomenon in this temperature range which was also affected by addition of such compounds as sodium chloride, urea, and dioxane. An anomalous behavior that cannot be explained as due to the relaxation phenomenon was observed on the addition of small amounts of these agents. One of the causes of this behavior is ascribed to the ion association in the solution. The static viscosity of the solution was also measured by using a rotating cylinder viscometer and the results compared with the dynamic data.
Light‐scattering study of the molecular weight distribution of polypropylene
Authors: Carpenter Dewey K. 
Published: April 2003

AbstractA light‐scattering study is presented of two isotactic polypropylene samples with broad molecular weight distributions (Mw/Mn = 8.1 and 8.7, respectively) dissolved in α‐chloronaphthalene at 147°C. Incident radiation of 5460, 4358, and 3650 A. was used. The reciprocal intramolecular scattering function, P−1(u) is expressed as a function of the variable [sin(θ/2)/λ′]2. This provides a wider range of experimental values of the variable u = 16π2(b2/6) [sin(θ/2)/λ′]2 than is accessible by the usual technique of using only one wavelength. The shape of the function P−1(u) is closer to that predicted theoretically if the weight distribution function f(N) in the equation

is given by the log‐normal distribution rather than the distribution function of Schulz and Zimm. The method is applicable to polymer samples for which the average molecular weights are too low to be measured by the light‐scattering method of Benoit and Loucheux.
Redox‐initiated vinyl polymerization with thiourea as the reductant
Authors: Mukherjee Asish R. , Pal Runu , Amarendra  , Biswas M. , Maiti Sukumar 
Published: April 2003

AbstractA few redox systems containing thiourea as reductant have been found to be quite effective in initiating vinyl polymerization in aqueous media and polymers obtained in the process have all been found to contain amino endgroups to various extents by the application of dye techniques. Quite a few oxidants have so far been utilized for this purpose; among them are ferric chloride (Fe3+), ethylene dibiguanide complex salts of tripositive silver (Ag3+), hydrogen peroxide (H2O2), persulfate (S2O82−), bromate (BrO3−) + hydrochloric acid (HCl). In case of oxidants Fe3+ and Ag3+, amino endgroups are mainly incorporated in polymers; but in case of oxidants H2O2 and S2O82−, fragments of oxidants are also incorporated as hydroxyl and sulfate endgroups. BrO3−, however, forms a very efficient redox‐initiating system with thiourea, as is evidenced by its capability of polymerizing even hydroquinone‐stabilized water‐soluble vinyl monomers at very low temperature (∼0°C.) and at a quite rapid rate. Besides amino endgroups, sulfonate endgroups have also been detected in polymers in this case, and the relative extents of these two types of endgroups depend generally on the acid concentration of the system. Evidences so far collected indicate the generation of SC(NH)NH2 radicals in the system by oxidation of isothiourea, HSC(NH)NH2, and these are incorporated in polymers as endgroups. Sulfonate endgroups may be generated by oxidation of these amino‐bearing endgroups. Suitable initiation mechanisms have been suggested in each case.
High‐pressure reactions. III. Hydrolysis of polyacrylonitrile
Authors: Prince M. , Hornyak J. 
Published: April 2003

AbstractPolyacrylonitrile prepared from γ‐irradiated monomer was found to react readily with water over a pressure range of 5,130–34,200 atm. to yield polyacrylamide, while polymer prepared by conventional free‐radical catalysts will not hydrolyze under the same conditions. Reaction rates at 85°C. were measured; hydrolysis was extremely rapid at higher temperatures. Results are presented to indicate the radical nature of the reaction. Addition of a free‐radical source increases the amount of hydrolysis. Pressure has an effect on the properties of the resulting polyacrylamide.
Emulsion polymerization of acrylonitrile. Part II. Mechanism of emulsion polymerization of acrylonitrile
Authors: Izumi Zenzi 
Published: April 2003

AbstractThe mechanism of emulsion polymerization of acrylonitrile has been studied by measuring by dilatometry and electron microscopy the adsorption of monomer into polymer particles and polymerization characteristics such as rate, degree of polymerization, the growth of the particle during polymerization, and the degree of dispersion. In the emulsion polymerization of acrylonitrile, new particles are formed during polymerization at a rate which is proportional to the rate of polymerization and the ratio of unreacted monomer. The total amount of monomer adsorbed on or in the polymer particles is rather small, but the concentration on or in the polymer particles is sufficiently high and proportional to the monomer concentration in aqueous phase. The polymerization proceeds concurrently on or in the polymer particles and in aqueous phase, but the three loci may be continuous rather than discrete. A reaction scheme is introduced here which shows the coexistence of polymerizations on or in the polymer particles and in the aqueous phase.
Phenyl‐substituted polyquinoxalines
Authors: Hergenrother Paul M. , Levine Harold H. 
Published: April 2003

AbstractFour phenyl‐substituted polyquinoxalines have been prepared by the reaction of combinations of two tetraamines, 3,3′‐diaminobenzidine and 3,3,′4,4′‐tetraaminodiphenyl ether, with two bisbenzils, 4,4′‐dibenzil and 4,4′‐oxydibenzil. The polymers were prepared by melt and solution polymerizations. Melt condensations were performed at 180, 220, and 280°C. and samples were periodically removed and characterized. The solution polymerizations consisted of two stages, initially forming an intermediate molecular weight polymer (ηinh 0.6–1.0) which was advanced at 400°C. to final polymer (ηinh 1.5 to 2.2). Clear yellow films, cast from m‐cresol solution, exhibited good toughness and flexibility. The phenyl‐substituted polyquinoxalines exhibited excellent oxidative and thermal stability. Polymer decomposition temperatures in air were generally about 550°C. Isothermal aging at 371°C. (700°F.) in air showed weight retentions as high as 93 and 50% after 100 and 200 hr., respectively. Weight‐average molecular weight determination by light‐scattering technique on a polymer with an ηinh of 2.16 suggested a value of 247,000. Certain physical properties of the phenyl‐substituted polyquinoxalines are compared with those of the corresponding ordinary polyquinoxalines to illustrate the advantageous effect of introducing a phenyl group on the quinoxaline ring.
Synthesis and properties of polyimidazopyrrolones
Authors: Bell Vernon L. , Jewell Robert A. 
Published: April 2003

AbstractThe preparation of polyimidazopyrrolones by three general synthetic methods has been presented. The effects of structure, conversion temperature, and conversion environment were determined. The polyimidazopyrrolones were shown to retain useful mechanical properties at elevated temperatures, after severe chemical treatment and after unusually high exposure to ionizing radiation. Thermogravimetric analysis of the polymers indicated the effect of structure on oxidative stability was relatively minor; furthermore, the relative stabilities of a series of eight polymers in air were not directly comparable to the order of stability in a vacuum environment.
Elastic behavior, birefringence, and swelling of amorphous polyethylene networks
Authors: Gent A. N. , Vickroy V. V. 
Published: April 2003

AbstractPolyethylene networks were prepared by γ‐irradiation of linear polyethylene, both molten and crystalline. The elastic and photoelastic properties of the networks were studied at high temperatures, i.e., in the molten state. The equilibrium swelling was also measured in several solvents. Values of the crosslinking efficiency G of γ‐radiation, the molecular, weight Me between entanglements, the optical anisotropy α of the equivalent random link, and the polymer‐solvent interaction parameter μ are deduced. Samples prepared by irradiation in the amorphous state showed markedly non‐Gaussian elastic behavior. The presence of a large non‐Gaussian term in the optical anisotropy is also deduced. The value of α obtained for swollen samples, which showed substantially Gaussian elastic behavior, was 3.9 × 10−24 cm.3, about one‐half of that obtained for dry samples. It corresponds to an equivalent random link of only about 5 CH2 units, on the basis of Denbigh's values for bond polarizabilities. The samples prepared by irradiation in the crystalline state showed lower values for α, which also depended upon the degree of crosslinking. This is attributed to the nonrandom chain configurations prevailing at the time of crosslinking. The same samples were found to show more nearly Gaussian elastic behavior, which is attributed to the same cause.
Annealing and melting of poly‐4‐methylpentene‐1 single crystals
Authors: Morrow D. R. , Richardson G. C. , Kleinman L. , Woodward A. E. 
Published: April 2003

AbstractThe effects of thermal treatment at temperatures in the 177–250°C. range for 2 hr. on solution‐grown single crystals of poly‐4‐methylpentene‐1 have been studied by using electron microscopy. Crystals were grown both from 0.02% pentyl acetate solution at 110°C. and from 0.02% toluene solutions at temperatures less than 80°C. A number of distinct types of crystals have been obtained in the same or in separate solutions depending on the crystallization conditions. These crystals have some morphological characteristics in common such as a square outline with well‐defined faces. The contrasting features include such things as a marked difference in relative size, with the smaller crystals showing extensive overgrowth and collapse markings. Observations by means of differential scanning calorimetry (DSC) on the melting behavior of these various crystals show the presence of distinct and characteristic melting points. The effects of a given thermal treatment depend on the type of crystals used, with the larger crystals showing greater stability. The first effects are the appearance of lines, notches at the edges, and holes. An increase in temperature results in an increase in these effects with the formation of fibrillar structures. Consideration is given to the influence of molecular conformation and molecular chain folding on the observed results.