bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative determination of short branches in high‐pressure polyethylene by gamma radiolysis
Authors: Kamath Pandurang M. , Barlow Anthony 
Published: April 2003

AbstractA careful study of the radiolysis products of a series of ethylene α‐olefin copolymers and ethylene homopolymers has shown that if a correction is applied, to take into account the fragments arising from scission at chain ends, the remaining products can be quantitatively accounted for as entirely due to scission of side branches introduced onto the backbone chain by the α‐olefin comonomer. The cleavage of branches takes place, for all practical purposes, exclusively at the branch points at which the branches are attached to the backbone chain. The same data together with similar radiolysis data of poly(3‐methyl pentene‐1) and poly(4‐methyl pentene‐1) have further shown that all branches cleave with equal efficiency, regardless of their length. Radiolysis does, therefore, provide a reliable and convenient tool for the quantitative characterization of high‐pressure polyethylene with regard to the unique short‐chain branching distribution that is characteristic of each.
Radical‐initiated copolymerization of carbon monoxide and ethylenimine in the presence of ethylene
Authors: Kagiya Tsutomu , Ichida Taizo , Narisawa Shizuo , Fukui Kenichi 
Published: April 2003

AbstractThe radical‐initiated copolymerization of carbon monoxide and ethylenimine in the presence of ethylene was studied quantitatively. Carbon monoxide copolymerized with difficulty with ethylenimine with α,α′‐azobisisobutyronitrile as radical initiator. In the presence of a small amount of ethylene, however, a remarkable amount of crystalline powdery poly‐β‐alanine (nylon 3) was obtained. The crystalline copolymer, which mainly consists of nylon 3 and contains a small amount of nylon 5 and other substances of higher homologous nylon structure, was obtained in the presence of a large amount of ethylene. This copolymer scarcely contained any ketone structure. Increasing the total feed of the equimolar mixture of the monomers increased the conversion of total monomer and nylon 3 content in the copolymer formed. The effect of increasing carbon monoxide content in this system was to increase both the conversion and the nylon 3 content in the copolymer. In both cases the copolymers were almost identical with nylon 3. Increased ethylene content in the monomer feed, however, increased the conversion and the content of higher homologous nylon structures, such as nylon 5 and 7. From the results it was concluded that ethylene was involved not only in the propagation reaction but also particularly in the initiation reaction.
The determination of randomness in copolyesters by high resolution nuclear magnetic resonance
Authors: Yamadera Reizo , Murano Masao 
Published: April 2003

AbstractHigh‐resolution nuclear magnetic resonance (NMR) spectra of several kinds of polyesters were measured. Proton signals due to heterolinkages could be observed in some copolyesters, and the average sequence length and the degree of randomness in the copolyester were calculated from the intensities of their signals. A process in the transesterification reaction between two kinds of homopolyester was pursued with the NMR spectra. Random copolyester is formed by the ordinary molten‐state copolycondensation and also during the transesterification reaction between two kinds of homopolyester.
Dehydrochlorination reactions in polymers. Part II. Chlorinated polystyrene
Authors: Haldon R. A. , Hay J. N. 
Published: April 2003

AbstractThe dehydrochlorination of chlorinated polystyrene was studied in the temperature range 120–220°C., when HCl was the sole volatile product. The dehydrochlorination was accompanied by the slow development of color and chain scission. The elimination rate fell too rapidly with reaction extent to be accounted for by reduction of reagent. Solution studies in o‐dichlorobenzene indicated that the reaction was initially first‐order in polymer concentration but was retarded by the polyene reaction products. The overall elimination was interpreted as a radical process in which the product was an active retarder. These observations are also valid for the elimination of HBr from brominated polystyrene.
Syntheses of polymerizable dyes and their graft copolymerization to cellulose and polypropylene fibers
Authors: Uno K. , Iwakura Y. , Makita M. , Ninomiya T. 
Published: April 2003

AbstractVarious methacrylic ester derivatives were synthesized from glycidyl methacrylate and aromatic amines or phenol. The homopolymerization and graft copolymerization of these compounds were carried out using azobisisobutyronitrile. These methacrylic derivatives reacted with diazonium salts to give azo compounds which have a double bond. These vinyl azo compounds gave homopolymer and graft copolymer with cellulose or polypropylene fibers.
Photochemistry of poly(tert‐butyl acrylate). Effect of ester spatial conformation on the cycloelimination process
Authors: Monahan Alan R. 
Published: April 2003

AbstractA preferred geometric isomer was found to exist for the Norrish type II photocycloelimination of isobutene from poly(tert–butyl acrylate). A detailed analysis of infrared spectroscopic and kinetic data under thin film conditions is consistent with the mechanism:
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i.e., a photoinduced rotational equilibrium is established between the cis and trans ester spatial conformations, with isobutene elimination occurring from the cis form. In the glassy state of the polymer, an activation energy of 3.0 kcal./mole was obtained for the elimination step. Energy transfer experiments with naphthalene, benzophenone, and oxygen resulted in a significant decrease in the isobutene yield. This indicates that reaction occurs at least in part from a triplet state of the carbonyl group in the polymer.
Preparation of fluorine‐containing polyethers
Authors: Trischler Floyd D. , Hollander Jerome 
Published: April 2003

AbstractPolyethers were prepared from 3,3,3‐trifluoro‐1,2‐epoxypropane by using both cationic and anionic initiators. Aluminum chloride and boron trifluoride were the two cationic initiators investigated. The polymer obtained with the use of aluminum chloride contained no functional endgroups other than hydroxyl, while the polymer prepared with boron trifluoride contained some terminal unsaturation. Potassium hydroxide and the monosodium salt of hexafluoropentanediol were investigated as anionic initiators. The polymer obtained by using potassium hydroxide also contained terminal unsaturation, while the polymer prepared with the monosodium salt of hexafluoropentanediol was terminated with primary hydroxyl groups capable of being used in polyurethanes. All polymers had molecular weights in the range from 970 to 4300. A fluorine‐containing polyformal was prepared in high yield by the reaction of hexafluoropentanediol with trioxane. The same polymer was obtained in poor yield by the reaction of hexafluoropentanediol with dibutyl formal. Ring‐opening polymerizations were attempted on two fluorinated cyclic ethers, 2,2,3,3,4,4‐hexafluoropentamethylene oxide and 3,3,4,4‐tetrafluorotetramethylene oxide. There was no reaction with anionic initiators. With most of the cationic initiators, there was no reaction. Boron trifluoride and phosphorus pentafluoride formed complexes with the ether, but would not cause ring opening.
Poly(aryl ethers) by nucleophilic aromatic substitution. I. Synthesis and properties
Authors: Johnson R. N. , Farnham A. G. , Clendinning R. A. , Hale W. F. , Merriam C. N. 
Published: April 2003

AbstractA series of new aromatic polyethers have been prepared by solution condensation polymerization. The synthesis involves the condensation of a dialkali metal salt of a dihydric phenol with an “activated” or negatively substituted aromatic dihalide in an anhydrous dipolar aprotic solvent at elevated temperatures. The reaction is rapid, free of side reactions, and yields polymers of excellent color. Bakelite polysulfone can be prepared in this manner by reaction of the disodium salt of bisphenol A with 4,4′‐dichlorodiphenyl sulfone in dimethyl sulfoxide (DMSO). Only dipolar aprotic solvents are useful for conducting the polymerization. Of these, DMSO and Sulfolane (tetrahydrothiophene 1,1‐dioxide) are the most effective. Water or other competing nucleophiles must be absent if high molecular weight is to be obtained. Besides providing the necessary solubility, this highly polar solvent is believed to be essential in providing the rapid polymerization rates observed. The rates are further found to depend on the basicity of the bisphenol salt and upon the electron‐withdrawing power of the activating group in the dihalide. As is usual for this type of reaction, the difluorides are found to be more reactive than the corresponding dichlorides. Most of the polyethers are amorphous, rigid, tough thermoplastics with high second‐order transitions (Tg). Thermal stability and electrical properties are noteworthy. These and other properties are described for polysulfone, and glass transitions are given for a selected list of the other polyethers.
Poly(aryl ethers) by nucleophilic aromatic substitution. III. Hydrolytic side reactions
Authors: Johnson R. N. , Farnham A. G. 
Published: April 2003

AbstractThe molecular weight of polysulfone, i.e., the aryl polyether that is prepared by the reaction of the disodium salt of bisphenol A with 4,4′‐dichlorodiphenyl sulfone in dimethyl sulfoxide (DMSO) solvent is shown to depend, among other things, on the moisture content of the polymerizing system. In the presence of water, hydrolysis of the sulfone monomer occurs concomitant with the polymerization. This leads to a deviation from the desired 1:1 ratio of coreactant groupings and therefore in attendant reduction in possible molecular weight. The hydrolysis is shown to lead to the formation of the sodium salt of 4‐chloro‐4′‐hydroxydiphenyl sulfone and to a lesser extent polymer derived from self‐condensation of this salt. At low levels this salt is essentially inert towards the principal polymerization at hand but in somewhat greater amounts functions as an effective chain terminator. Similar hydrolysis of polysulfone chloro endgroups is believed to occur under the aqueous conditions of polymerization but to a lesser extent than for the sulfone monomer. It is shown that polysulfone or similar polyethers are subject to chain cleavage by bases in DMSO solvent. The base attacks the activated position para to the sulfonyl group with the formation of a chain terminating in a bisphenol A type phenolic group and a chain terminating in a phenolic group of the bisphenol S (p‐hydroxyphenyl sulfonyl) type. It is shown that cleavage is probably not important under normal conditions of polymer formation. The effect of these hydrolytic side reactions on the attainment of high molecular weight under conditions of imperfect reaction stoichiometry is shown to be consistent with the above conclusions.
Syntheses of optically active polymers by condensation polymerization of d‐tartaric acid with some diamines
Authors: Minoura Yuji , Urayama Shigeru , Noda Yuzuru 
Published: April 2003

AbstractIn order to synthesize optically active polymers which have asymmetric carbon atoms in the polymer main chain, polyamides were synthesized at high temperatures by the condensation of the salt prepared from d‐tartaric acid with diamines, such as hexamethylenediamine, o‐, m‐, and p‐phenylenediamine. Effects of the solvent, polymerization time, intrinsic viscosity, and pH on the degree of the specific rotation of polyhexamethylene‐d‐tartaramide, were investigated. From the results of hydrolyses of the polymers, it was found that d‐tartaric acid is not racemized during condensation polymerization.
Anionic graft polymerization of methyl acrylate to protein functional groups
Authors: Krull L. H. , Friedman Mendel 
Published: April 2003

AbstractGraft polymerization of methyl acrylate to functional groups in proteins was studied with model compounds and with whole gluten proteins. Polymerization was carried out in the presence of sodium hydride or sodium in dimethyl sulfoxide. Initiation proceeds by an anionic mechanism, and the rate‐determining step is the production of the initially formed carbanion. The rate of disappearance of methyl acrylate was followed via gas chromatography. Amino acid analyses indicated that the functional groups of the amino acids, as well as the peptide bonds, were acting as the initiation sites in proteins. Reaction rates of the functional groups were determined on model compounds in the presence of sodium and sodium hydride. With both the model compounds and the proteins, polymerization was initially rapid and then leveled off, although rates depended on the concentration of activator and acrylate. Methoxyl group analyses of modified model compounds and proteins indicated that from 5 to 10 methyl acrylate residues were introduced per reactive site.
Effect of chemical reagents on the fine structure of cellulose. Part IV. Action of caustic soda on the fine structure of cotton and ramie
Authors: Warwicker J. O. 
Published: April 2003

AbstractAn x‐ray study has been made of the changes in lateral order that take place on the treatment of cotton and ramie with different concentrations of caustic soda at 0 and 20°C. When mercerization conditions are reached it is found that there is an increase in lateral disorder in the fibrils. The x‐ray diagrams from samples treated in the higher concentrations of caustic soda reveal a residual diffraction effect that can be interpreted in terms of a special type of cellulose sheet. This result implies one extreme of lateral disorder that is present in the fine structure of these materials. Indication is given how these lateral disorder phenomena can affect reactivity.
Post‐lactonization of vinyl polymers containing pendent ester and hydroxymethyl groups
Authors: Powell John A. , Whang Jong J. , Owens Frederick H. , Graham Roger K. 
Published: April 2003

AbstractCopolymers of methyl methacrylate with methyl and ethyl α‐hydroxymethylacrylate and with α‐hydroxymethylstyrene have been prepared with free‐radical initiators at temperatures below 80°C. At higher reaction temperatures or under extrusion conditions, alcohol was eliminated and the free hydroxyl content was greatly decreased. All evidence indicates the formation of six‐membered lactone groups in this post‐polymerization reaction: direct evidence for their formation is lacking, however, since neither infrared nor nuclear magnetic resonance spectra could be used to detect lactonization in this system. The loss of activity from 14C ester‐labeled methyl methacrylate copolymer on heating could be correlated with the extent of lactonization. The degree of lactonization is relatively less with copolymers containing higher amounts of hydroxymethyl groups. The resulting polymers exhibit higher heat distortion temperatures and decreased impact resistance when compared to poly(methyl methacrylate). Attempts were made to incorporate similar lactone structures by cyclocopolymerization with methyl methacrylate of α‐methacryloxymethylstyrene or ethyl α‐methacryloxymethylacrylate, but only crosslinked polymers or polymers with pendent unsaturation were found.
Emulsion polymerization of vinyl stearate
Authors: Moore D. E. 
Published: April 2003

AbstractThe polymerization of vinyl stearate in aqueous emulsions with a non‐ionic emulsifying agent and potassium peroxydisulfate as initiator has been investigated by use of a dilatometric method to follow the reaction. In general, the reaction kinetics do not follow the pattern established for styrene. Variation of initiator concentration produced latices containing approximately equal numbers of latex particles, even though the rate of reaction was almost directly proportional to the peroxydisulfate concentration. For a given initiator and monomer concentration polymerization occurs very slowly when the monomer is completely solubilized but as the number of micelles is reduced and the number of emulsion droplets increased, the rate increases to an optimum value, whereafter it decreases. A mechanism is proposed by which the sparsely soluble vinyl stearate reacts and redistributes itself into latex particles of a different size range from the micelles and emulsion droplets originally present.
Polymerization initiated by an electron donor–acceptor complex. Part I. Polymerization of methyl methacrylate initiated by liquid sulfur dioxide–pyridine complex in the presence of carbon tetrachloride
Authors: Matsuda Minoru , Hirayama Takeshi 
Published: April 2003

AbstractThe polymerization of methyl methacrylate can be initiated by a charge‐transfer complex of liquid sulfur dioxide and pyridine in the presence of carbon tetrachloride. The molar ratio of sulfur dioxide and pyridine which participated in the complex was found from a spectrophotometric study to be 2:1. The polymerization proceeds through free‐radical intermediates. The overall rate of polymerization is proportional to the square root of the concentration of the complex, and the values of kp/kt1/2 under the various polymerization conditions were satisfactorily consistent with the literature value. For the activation energy of the overall reaction, 8.2 kcal./mole was obtained, and for initiation, 9.7 kcal./mole was evaluated from the values of kp/kt1/2. It was deduced from a kinetic mechanism for the initiation that a primary radical may be produced from the reduction of carbon tetrachloride by an associated complex consisting of liquid sulfur dioxide–pyridine complex and the monomer.
Anionic copolymerization of styrene and isoprene in cyclohexane
Authors: Worsfold D. J. 
Published: April 2003

AbstractThe copolymerization of isoprene with styrene initiated with sec‐butyllithium in cyclohexane solution has been studied by kinetic methods. The rates of the homopolymerization have been measured by normal methods. The rates of the cross‐propagation reactions were measured by the rate of appearance or disappearance of the ultraviolet absorption of polystyryllithium when the individual chain ends were reacted with the opposite monomer in the absence of the first. The rates of some of the reactions were also measured in the presence of the other monomer. It was found that polyisoprenyllithium reacted with both monomers with a one quarter‐order dependence, and the polystyryllithium with a one half‐order dependence. It was found possible to describe the copolymerization in terms of the four individual rate constants and to predict the initial copolymer composition. It was not found necessary to resort to explanations based on preferential absorption of isoprene around the chain ends to explain the high isoprene content of the copolymer.
Influence of SeOCl2 on the polymerization of propylene by TiCl3–Al(C2H5)3
Authors: Soga Kazuo , Takano Yoshiji , Go Shigeo , Keii Tominaga 
Published: April 2003

AbstractThe influence of SeOCl2 on the polymerization of propylene by TiCl3–Al(C2H5)3, and the temperature dependence of the stereospecificity of the catalyst, TiCl3–Al(C2H5)3, have been investigated. SeOCl2 decreases the rate of polymerization and increase the stereospecificity of the catalyst, which could be explained on the basis of a decrease of the concentration of Al(C2H5)3 accompanied by a reaction between Al(C2H5)3 and SeOCl2. On the other hand, the stereospecificity of the catalyst, TiCl3–Al(C2H5)3, increases gradually with a decrease in polymerization temperature from 40 to 0°C. From these results, we conclude that SeOCl2 exerts no essential influence on the polymerization of propylene by TiCl3–Al(C2H5)3, and that the stereospecificity of the catalyst is attributed mainly to the reducing ability of the organometallic compound.
Synthesis of poly‐3,3‐bis(chloromethyl)‐oxacyclobutane (penton) derivatives
Authors: Minoura Yuji , Shiina Kyo , Yoshikawa Keizo 
Published: April 2003

AbstractThe derivatives of poly‐3,3‐bis(chloromethyl)oxacyclobutane were prepared by the reaction of the chloromethyl group with organic alkali salts at 100–130°C. in dimethyl sulfoxide. Various reagents were used, including sodium cyanide, sodium acetate, sodium thiophenolate, sodium phenolate, sodium methoxide, sodium diethyl malonate, and potassium phthalimide. For all the substitution reactions, the infrared spectra and elementary analyses substantiated the structures of the designated products. The intrinsic viscosities of the derivatives decreased with increasing the reaction time. It was found that the ions of these salts are strong nucleophiles in dimethyl sulfoxide.
Polymerization of vinylbenzamides
Authors: Negishi Sutemi , Tamura Yorikazu 
Published: April 2003

AbstractIn the base‐catalyzed polymerization of p‐vinylbenzamide, hydrogen‐transfer polymerization occurs. The structure of the new polymer was identified. Various effects on the hydrogen‐transfer polymerization of p‐vinylbenzamide were studied. The infrared spectrum of the oligomer has characteristic absorptions of secondary amide, as well as weak absorption of the vinyl group. The oligomer also gives a hydrogen‐migrated polymer with anionic catalysts. From these facts a possible polymerization mechanism was proposed. The hydrogen‐transfer polymerization occurred most readily with the p‐vinylbenzamide, next and to a small extent with the meta‐substituted isomer, and hardly with the o‐substituted isomer. o‐Vinylbenzamide gives 3,4‐dihydroisocarbostyril.
Polymerization of tetraoxane at low concentration catalyzed by BF3·O(C2H5)2
Authors: Miki T. , Higashimura T. , Okamura S. 
Published: April 2003

AbstractIn the solution polymerization of tetraoxane catalyzed by BF3·O(C2H5)2, trioxane and methanol‐insoluble polymer were produced. However, the amounts of these products depend on the nature of solvent used. A critical concentration of tetraoxane is observed for the formation of methanol‐insoluble polymer; at less than this critical concentration of tetraoxane no methanol‐insoluble polymer is obtained, but trioxane is preferentially produced. This critical concentration of tetraoxane is higher in a more polar solvent, so the amount of methanol‐insoluble polymer produced decreases and the amount of trioxane produced increases with increasing the polarity of solvent used. These results may be explained in terms of a stabilization of the active center leading to formation of trioxane by a solvation with solvent.
Mechanisms of propagation, transfer, and short‐chain branching reactions in the free‐radical polymerization of ethylene
Authors: Machi Sueo , Kise Seiichi , Hagiwara Miyuki , Kagiya Tsutomu 
Published: April 2003

AbstractThe propagation, transfer, and short‐chain branching reactions in the free‐radical polymerization of ethylene were studied at temperatures of 20–80°C. under pressures of 160–400 kg. cm.2 by means of two‐stage polymerization with the use of a specially designed reaction vessel. In the first stage, the polymerization was carried out in the presence of AIBN as the initiator, and in the second stage, the propagation occurred with living radicals in the absence of the initiator. In the second stage the polymer yield is shown to increase with reaction temperature and pressure, and the molecular weight of the polymer reached constant values which were dependent upon the temperature when the contribution of the polymer formed in the first stage was very small. It is shown that in the second stage the rate of propagation, transfer, and short‐chain branching are all proportional to the second power of ethylene fugacity, and that the activation energies of these reactions are 5.7, 23.4, and 10.9 kcal./mole, respectively. The polymer has no terminal vinyl group. The mechanism of these reactions is discussed on the basis of kinetic and energetic results.