bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationship between stereostructure of poly(vinyl alcohol) and its acetalization reaction
Authors: Shibatani Kyoichiro , Fujii Kiyoshi , Ōyanagi Yasuji , Ukida Junji , Matsumoto Masakazu 
Published: June 2010

AbstractBy measurement of peak areas in the dioxymethylene region of high‐resolution NMR spectra of partly formalized poly(vinyl alcohol), PVA, the relationship between tacticity of PVA, rate of formalization reaction, and stereochemical configuration of poly(vinyl formal) was studied. Formation of cis‐formal at an isotactic part of a PVA chain is faster than that of trans‐formal at a syndiotactic part. When the reaction is allowed to continue for a long period, the migration of formal rings from syndiotactic to isotactic portions is observed. Partition of formal rings in partly formalized PVA into cis and trans types is discussed in connection with the tacticity of original PVA and degree of formalization. The rate‐determining step of acetalization reaction is also discussed.
New polymers derived from dihydrazine derivatives
Authors: Takahashi Hiroshi , Hasegawa Masaki , Okada Akira 
Published: June 2010

AbstractNew types of N‐substituted polyureas and N‐substituted polysemicarbazides were prepared from the reaction of 1,6‐bis‐[α(or β)‐N‐substituted hydrazino]hexane or 4,4′‐bis‐[β‐N‐substituted hydrazino]diphenyl methane with diisocyanate. These hydrazine derivatives were derived from dihydrazine with diphenyl carbonate or phenyl benzoate. Successful results were obtained in solution polymerization. The polymers are soluble in N,N‐dimethyl formamide, m‐cresol, and hexamethyl phosphoramide, and show relatively high polymer melting temperature. The reactivity of the carbophenoxy group in the polymer side chain was also examined.
ESR studies of polypropylene with different stereospecificities
Authors: Kusumoto Naoshi 
Published: June 2010

AbstractIsotactic (IPP), syndiotactic (SPP) and atactic (APP) polypropylene were irradiated by gamma‐rays of 60Co at −196°C., and ESR spectra were subsequently examined in conjunction with the stereospecificities and regularities of the polymers. All the polymers showed similar broad spectra at −196°C. APP gave a well‐resolved sextet spectrum above −40°C., which vanishes at about −10°C., owing mainly to its glass transition. IPP and SPP showed different spectra characteristic of their stereospecificities in the crystalline phase above room temperature. It was concluded that the radical species at room temperature are identical in IPP and SPP except for their steric conformations. The coupling constants of protons of the radical of SPP were determined in comparison with those reported for IPP, assuming the allyl‐type radical CH(CH3)CHCH(CH3)CHCH(CH3)2. The decay process of the radicals was found to be a second‐order reaction. The study shows that only the spectrum of IPP exhibits a singlet when the sample is kept at room temperature in vacuum. The spectrum of SPP is easily saturated compared with that of IPP when the power of the oscillating magnetic field is increased.
N‐substituted styrene–maleimide interpolymers
Authors: Pratt R. J. , Strand R. C. 
Published: June 2010

AbstractThe classic method of converting anhydrides to imides by reaction with ammonia or amines was applied to low molecular weight co(styrene–maleic anhydride) polymers. In preference to direct‐melt, solid–gas, and solid–liquid reactions, an in situ esterification step with amyl alcohol as solvent and reactant was employed for the imide synthesis. In this manner the reaction system was kept fluid, homogeneous, and selective even with difunctional reactants. This procedure was applied to ammonia, octadecylamine, dimethylaminopropylamine, and monoethanol‐amine. The maleimide copolymer resulting from ammonia was converted to hydroxmethyl, chloromethyl, pyridyl chloromethyl, aminoethyl, dimethylamino, and glycidyl derivatives.
Grafting of poly(vinyl acetate) to granular corn starch
Authors: Brockway C. E. 
Published: June 2010

AbstractVinyl acetate forms graft copolymer with granular corn starch when initiated by peroxide plus activator in an aqueous slurry of the starch. Grafting efficiencies are less than 50%, much lower than realized with either acrylonitrile or methyl methacrylate under comparable conditions. Grafting efficiency can be raised by including with the vinyl acetate a minor amount of comonomer. Among the comonomers used, methacrylic acid and methyl methacrylate were particularly effective for increasing the grafting of vinyl acetate.
Chemical modification of wheat gluten proteins and related model systems
Authors: Wall J. S. , Friedman M. , Krull L. H. , Cavins J. F. , Beckwith A. C. 
Published: June 2010

AbstractSelected chemical modifications of wheat gluten protein were conducted to provide basic information on its chemistry and behavior and to improve it for various applications. Wheat gluten protein was subjected to acid‐catalyzed methanolysis of the numerous side‐chain amides of the glutamine residues. The formation of γ‐glutamyl methyl ester groups decreased the solubility of the protein in polar solvents and enhanced it in less polar solutions. Reduction and reoxidation of the disulfide bonds of cystine in gluten caused marked changes in the conformation and intermolecular crosslinking of the proteins. The rate and products of reoxidation were determined by concentration of the protein, nature of the solvent, and amino acid composition of the proteins. The rate of alkylation of polar functional groups of proteins by α,β‐unsaturated compounds such as acrylonitrile was shown to be determined by the pH, polarity, steric environment, and relative nucleophilicity of the specific group. According to these observations it may be possible to establish conditions in which sulfhydryl groups on proteins could be preferentially alkylated or extensive alkylation of other groups could occur. The polymerization grafting of methyl acrylate to gluten was accomplished by anionic mechanisms in a homogeneous system containing aprotic solvents. Grafting was found to occur on most functional groups.
Some properties of collagen modified by the Mannich reaction
Authors: Feairheller S. H. , Taylor Maryann M. , Gruber Helen A. , Mellon E. F. , Filachione E. M. 
Published: June 2010

AbstractThe Mannich reaction of several aliphatic active hydrogen compounds with formaldehyde and collagen, the principal protein of animal hides and skins, was investigated. These reactions were all carried out under extremely mild conditions: aqueous solutions buffered at about pH 4 and at or slightly above room temperature. The sites of the reaction in the protein were found to be the lysine, hydroxylysine, and histidine residues. The extent of the reaction and the effects of various factors on the reaction also were determined. Although polyfunctional active hydrogen compounds were used, there was little indication that cross‐linking had taken place. With acetylacetone and methyl acetoacetate the evidence indicated that dihydropyridines were formed. The extent of such a reaction was calculated from ultraviolet absorption data and from the amino acid analysis of the chemically modified proteins. The results of the two methods were in extremely good agreement with each other. With malonic acid a product was formed that offers potential for practical application. A number of new compounds were found in the hydrolyzate of the product. Two of these were identified as N ϵ‐(β‐carboxyethyl)‐L‐lysine and Nϵ, Nϵ‐bis(β‐carboxyethyl)‐L‐lysine.
Acryloylpolystyrene
Authors: Leavitt F. C. , Rubens L. C. 
Published: June 2010

AbstractReactive pendant acryloyl groups can be substituted for hydrogen in the para position on the phenyl groups in polystyrene. Acylation of the polymer with β‐chloropropionyl chloride in solution is followed by dehydrochlorination, yielding acryloylpolystyrene (AP resins). Both the molecular weight of the polymer and the number of acryloyl groups per polymer molecule can be varied over wide limits. AP resins dissolve readily in vinyl aromatic monomers and copolymerize readily with them to yield clear, colorless, infusible polymers with good strength properties. The rate of copolymerization of these mixtures increases with both the number of acryloyl groups and the amount of acryloylpolystyrene in solution. These resins are similar in polymerization behavior and strength properties to the unsaturated polyesters used for production of glass‐reinforced plastics. In addition, the acryloyl groups are available for other reactions in a manner comparable to that of monomeric analogues.
Chlorination of preformed polyethylene film
Authors: Luttinger Manfred , Cooper Charles W. , Hungerford Gordon P. 
Published: June 2010

AbstractSubstantial chlorination of polyethylene (PE) films has been accomplished, making available films having wide varieties of physical properties. The reaction of thin PE films of 0.918 to 0.935 g./cm.3 density was investigated in an atmosphere of Cl2 and in a liquid medium saturated with Cl2. Chlorine contents from 10 to 30% in low‐density films and up to 45% in medium‐density films were obtained by reaction in the gaseous phase. By the use of various light sources in conjunction with peroxydic catalysts chlorine contents of up to 70% were achieved in glacial acetic acid. In the gaseous atmosphere the tendency of the reaction rate to decrease after light chlorination suggests that diffusion may be the limiting factor here. In the liquid medium the barrier to substitution above 65 to 70% appears to have a thermodynamic basis. The tensile strength and stiffness of the films pass through a minimum below 40% chlorine content and are affected by the reaction temperature. Mildly chlorinated films that have reacted at 40°C. do not exhibit a marked change in tensile properties, suggesting possible chain scission or a decrease in crystallinity on chlorination at elevated temperatures. Significant increases in the fusion point of PE are realized even with low substitutions of chlorine.
Reactions at the terminal vinyl group in Phillips‐type polyethylene
Authors: Zeitlin R. J. 
Published: June 2010

AbstractPolyethylene is commonly considered an inert aliphatic hydrocarbon similar to the lower alkanes. When produced by the Phillips process, it does contain one terminal vinyl group. The reaction in the melt with dibutyl maleate initiated by tert‐butyl hydroperoxide was studied in a Brabender Plastograph. Comparative reactions of alkanes, 1‐alkenes, and 2‐alkenes of low molecular weight with dibutyl maleate were also carried out. An appreciable addition of dibutyl maleate to vinyl groups occurred with Phillips polyethylene, 1‐decene, and 1‐octene, but not with 2‐octene or octane. Dibutyl succinate also is a principal product of the reaction. Polyethylene modified by chemical reaction with dibutyl maleate has greatly increased elongation and environmental stress‐crack resistance and lowered flexural modulus and brittle temperature.
Oxidation of butadiene polymers
Authors: Bevilacqua E. M. 
Published: June 2010

AbstractButadiene polymers and copolymers undergo both scission and cross‐linking during thermal oxidation, the scission exceeding the crosslinking by a small amount. As a result initially soluble polymer develops gel and insoluble polymer develops sol. A limiting solubility is reached rapidly. This affords a quantitative estimate of the scission‐to‐cross‐linking ratio. Vulcanization with sulfur and accelerators causes a much more complex change on oxidation, not easily described by solubility analyses. Reaction with sulfur causes an excess of crosslinking over amount of scission during oxidation. Formic acid is a major low molecular weight product of oxidation. Higher molecular weight fragments include acetone and acetaldehyde; others have not been identified. These products do not provide the helpful clues to the oxidation mechanism afforded, for example, by levulinaldehyde in the case of polyisoprene.
The hydrogenation of poly‐2‐alkylbutadienes
Authors: Gregg E. C. 
Published: June 2010

AbstractComplete hydrogenation of cis‐polyisoprene has been effected at 240°C. and 3,600 psi of hydrogen pressure over Raney nickel for 48 hr. Only a moderate amount of polymer breakdown occurred. High molecular weight hydrogenated polyisoprene was obtained by fractionating the hydrogenated polymer. Under similar conditions trans‐polyisoprene, poly‐2‐ethylbutadiene, poly‐2‐n‐propylbutadiene, poly‐2‐n‐pentylbutadiene and poly‐2‐(2‐methyl‐2‐penten‐5‐yl) butadiene were completely hydrogenated. No rearrangement of the polybutadienes as a result of hydrogenation was observed.
Shell model calculations of translational and rotational frictional coefficients
Authors: Bloomfield Victor A. , Filson Don P. 
Published: June 2010

AbstractPrevious work has shown that it is possible to calculate the translational and rotational frictional coefficients of complex structures by modeling them by a surface shell of spherical elements. The basic equations of this shell model method and its application to spheres, prolate ellipsoids of revolution, proteins, and viruses, are reviewed here. Several new results are also presented. It is demonstrated analytically that the rotational frictional coefficient for a sphere, calculated according to the shell model, agrees with the Stokes‐Kirchoff law. The rotational frictional coefficients of right circular cylinders have been calculated by digital computation; end effects are less marked than they are according to a theory of Broersma. Finally, the sedimentation behavior of various geometrical arrays of oligomeric aggregates of spherical subunits has been tabulated, to facilitate application to multichain protein systems.
Computer solution of gel–crosslink relations
Authors: Kang H. Y. , Saito O. , Dole M. 
Published: June 2010

AbstractUse of the Wesslau molecular weight distribution equation in the equations relating production of gel to total radiation dose leads to equations that can be solved only by means of computer techniques. This solution has been carried out for a number of initial values of the weight‐average to number‐average molecular weight ratios and for a number of ratios of chain degradation G values to crosslink G values. It is shown that the initial slope of the curve of s + s1/2 versus rg/r, where s is the soluble fraction after a dose r, and rg is the dose to the gel point, can be related to the type of initial molecular weight distribution in the polymer. For the first time definite evidence of an increase of the crosslinking rate with dose has been obtained.
The alteration of molecular weight distributions of polymers by ultrasonic energy
Authors: Heymach George J. , Jost Donald E. 
Published: June 2010

AbstractMethods of producing selected monodispersed samples of addition polymers have gained importance in many phases of polymer research. The ability of cavitation resulting from intense ultrasonic energy selectively to degrade polymers by fracturing longer chains at a faster rate than shorter chains is investigated as a means of sharpening molecular weight distributions. Conflicting degradation theories and experimental findings are reviewed, and new degradation models based on reasonable degradation mechanisms are developed. An IBM 7040–1401 computer was used to simulate degradation for these models. The solutions show in detail how molecular weight distributions are shifted and altered, depending on the kinetic expression used. In all the cases investigated monodispersity is first seen to decrease and then increase as a function of time.
Applicability of HLB system in selecting emulsifiers for emulsion polymerization of vinyl chloride
Authors: Testa F. , Vianello G. 
Published: June 2010

AbstractThe choice of the proper emulsifier in the emulsion polymerization of vinyl chloride is very complicated since it greatly affects not only the reaction proceeding but also the physical‐chemical and technological properties of the final product. Greth and Wilson successfully applied in the emulsion polymerization of styrene and vinyl acetate the choosing method of emulsifiers based on their HLB value. The scope of this work was to ascertain if the HLB system could be employed in the emulsion polymerization of vinyl chloride which, due to several features, is different from that of styrene and vinyl acetate. By blending together pairs of emulsifiers of different HLB values it was possible to prepare three series of emulsifier blends covering a wide range of HLB values. The most important properties of the emulsion polymerization of vinyl chloride, i.e., conversion rate, latex stability, particles size, and distribution were plotted against HLB values of emulsifier blends. No bell‐shaped curves were obtained, as should be expected, but the properties considered seemed to depend rather upon the amount of the blend component that strongly affects the polymerization, i.e., Empicol and Na‐laurate. It may be that the poly (vinyl chloride) insolubility in its monomer changes the properties of the latex particle so that it does not follow the emulsification laws on which the HLB system is based.
The characterization of monodisperse polystyrene latices
Authors: Shaw J. N. 
Published: June 2010

AbstractFour monodisperse polystyrene latices, containing particles of diameter ca. 2400 Å, were prepared using hydrogen peroxide and potassium persulfate as initiators and sodium dodecanoate, sodium mono‐dodecyl phosphate, and dodecylamine hydrochloride as emulsifiers. These latices were characterized by electron microscopy, gas adsorption, and microelectrophoresis. The results obtained by the first two techniques indicated that the particles were essentially nonporous rigid spheres. Electrokinetic procedures were used to characterize the ionogenic groups on the latex particles. In addition to the emulsifier molecules, other groups, namely carboxylic acid groups, were found to be present on all of the latices, irrespective of the nature of the initiator or umulsifier used to produce them, Electrophoresis also revealed that the emulsifiers could be removed from the latex dispersions by dialysis, leaving systems with these carboxyl groups as an integral part of the particle surfaces. By electrokinetics, the surface pK value of these unknown acid groups was 4.64. It was also established by radiochemical methods, combined with microelectrophoresis, that sodium dodecanoate was removable by dialysis from polystyrene latices. Before dialysis the concentration of the free emulsifier was below the critical micelle concentration. The latter experiments also suggested that the construction of adsorption isotherms from electrokinetic data is of doubtful validity. The integral carboxyl groups were probably produced by polymer oxidation during polymerization.
Studies of adsorption onto synthetic latices
Authors: Brodnyan John G. , Kelley E. Lloyd 
Published: June 2010

AbstractDespite the importance of reactions at the polymer‐water interface of synthetic latices very little work has been reported on the adsorption of surfactants or water‐soluble macromolecules at this site. In the studies reported here the adsorption isotherms of sodium lauryl sulfate onto polystyrene and poly(n‐butyl methacrylate) and of hydroxyethyl cellulose onto poly(n‐butyl methacrylate) are shown to be of the Langmuir type. Other water‐soluble macromolecules and latex substrates were studied at a single macromolecule content and a single latex solids level. The effective surface area of the sodium lauryl sulfate molecule, at the critical micelle concentration, was found to be 58.5 Å2 for both polystyrene and poly(n‐butyl methacrylate). This is in good agreement with results obtained by soap titration. The adsorption of macromolecules is strongly influenced by macromolecule type as well as by the latex substrate, i.e., the type of surfactant on the latex surface as well as the polymeric composition of the latex.
Displacement of hydrophilic colloids from particle interfaces
Authors: Kreider R. W. 
Published: June 2010

AbstractThe viscosity increase observed when hydrophilic colloids are added to latex/pigment systems indicates strong interaction between particles and macromolecules. The interaction is caused by partial adsorption of the macromolecule with a segment free to expand to a nearby particle to form a rigid network. Attempts were made to displace macromolecules from PVAc copolymer and pigment particles. Displacement of the hydrophilic colloid from the particles into the water phase reduced shear stress as demonstrated by flow curves obtained with the Haake Rotovisco. Rheological measurements with the latex serums obtained by ultracentrifuging and reconstruction of the latex aqueous phases confirmed that the abnormal viscosity increase in the latex is caused by link formation. Nonionic surfactants are amphipathically adsorbed at the particle interface and the macromolecules appear to hydrogen bond to the surfactant hydrophile. Segments of the macromolecules remain free, however, to project into the water phase and form linkages. Post‐addition of anionic surfactants from an homologous series produced marked rheological changes in latex/pigment systems. The disarrayed existence of the macromolecules in the water phase produces flow curves that are consistent with those of the hydrophilic colloid dissolved in water.
The helical structure of a β‐D‐1,3‐xylan
Authors: Atkins E. D. T. , Parker K. D. 
Published: June 2010

AbstractA structure determination is described of a naturally occurring non‐cellulosic polysaccharide which is found in the cell wall of some siphoneous green algae. The structure consists of three β‐1,3‐linked xylan polymer chains intertwining, each helical chain having exactly six residues in a pitch of 18.36 Å. The evidence is in favor of right‐handed helices with stoichiometrically bound water. There is a novel interchain hydrogen bond system at the center of the structure.
Simulation of the gel structure of regenerated cellulose film
Authors: Haskell V. C. 
Published: June 2010

AbstractThere is a growing body of experimental evidence that regenerated cellulose in the gel state is like a random network of microfibrils perfused by water. If this is true, the properties of both the gel and dried structures should be profoundly influenced by the geometrical properties of the network. In this work a computer program was developed with which a random interconnected network of linear structural elements could be generated. During collapse of the network in the thickness direction, which simulated drying, new junctions were formed which could lock in strains imposed on the structure during drying. From the results geometric explanations were proposed for the dimensional instability of cellulose film in varying humidities, for the mechanical behavior of the film, and for the effect of softening and of crosslinking on film properties.
An approach to biosynthesis of organic superconductors
Authors: Kagan Norman E. 
Published: June 2010

AbstractAs a striking similarity exists between the structures of the proposed organic superconductors and certain naturally occurring products of biological activity, it seems reasonable to ask whether Nature has already utilized this phenomena in a living system or whether she might be induced to do so. One test of this hypothesis would be to establish an artificial environment whereby a selective advantage is given to those organisms which show signs of macroscopic superconductivity. An experiment will be described in which bacteria are screened and bred for traits such as heightened conductivity and diamagnetism in an attempt to evolve cells with these properties.