bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stereochemical configurations of polypropenes by high resolution nuclear magnetic resonance
Authors: Stehling Ferdinand C. 
Published: April 2003

AbstractHigh resolution hydrogen NMR spectra of amorphous, stereoblock, and isotactic fractions of polypropylene show distinct differences. The spectra are complex but those of polypropene‐2‐d1 and polypropene‐2,3,3,3‐d4 are simple and easily interpreted. The differences in the spectra of the amorphous, stereoblock and isotactic fractions of the polymers is the result of a difference in the chemical shifts of isotactic and syndiotactic type methylenes. The ratio of the types of methylenes can be estimated from the spectra of polypropene‐2,3,3,3‐d4. In isotactic polymer the concentration of syndiotactic type methylenes is below the limit of detection. Assuming that the inversions in stereochemical configuration are randomly distributed along the polymer chain, the average length of sterically identical segments in stereoblock polymer is about fifteen monomer units. In amorphous polymer the ratio of isotactic to syndiotactic type sequences is approximately one. The spectra of the deuterated polymers show no detectable rearrangement of hydrogen and deuterium atoms in the polymerization.
Metal chelates of polyhydrazides
Authors: Frazer A. H. , Wallenberger F. T. 
Published: April 2003

AbstractTwo all‐aromatic polyhydrazides have been investigated with respect to their propensity to form metal‐chelate bulk polymer, films, and fibers. The aromatic polyhydrazide derived from isophthalic acid was found to give chelate bulk polymer with Ni+2, Ca+2, Ag+1, Hg+2, Pb+2, Zn+2, Cd+2, and Cu+2 which analyze for a 1:1 ratio of hydrazide link:metal ion. Films of the polyhydrazide–metal chelate were prepared by soaking polyhydrazide films in dimethylformamide solutions of metal salts. Tough fibers of the polyhydrazide–metal chelates with such metal ions as Cr+3, Co+2, and Ag+1 were prepared by passing polyhydrazide fiber through dimethylformamide solutions of these metal salts.
Bis(imidazolato)–metal polymers
Authors: Brown G. P. , Aftergut S. 
Published: April 2003

AbstractThe reaction of imidazole and the sulfates of Cu(II), Zn(II), and Co(II) in aqueous NaHCO3 gave products whose analysis corresponded to two imidazole residues per metal atom. The products were insoluble in common organic solvents and had very high melting points. Thermogravimetric analyses revealed that the Co‐ and Zn‐containing materials had unusually high thermal stability, as no loss in weight could be detected below 500–575°C. when heated in nitrogen. The properties led to their formulation as metal coordinate polymers. The electrical resistivity of the products was in excess of 1015 ohm‐cm. at 140°C.
Reactivities of esters of methacrylic acid. Part I. Relative reactivities of esters toward the benzoyloxy radical
Authors: Bevington J. C. , Malpass B. W. 
Published: April 2003

AbstractTracer methods have been used to compare the reactivities of methyl, ethyl, phenyl, benzyl, and cyclohexyl methacrylates toward the benzoyloxy radical at 60°C. Certain of the characteristics of the polymerizations of these monomers are recorded.
Proton resonance spectra and tacticities of some poly(methyl vinyl ethers)
Authors: Brownstein S. , Wiles D. M. 
Published: April 2003

AbstractMethyl vinyl ether has been polymerized by BF3 etherate catalyst under a variety of conditions to obtain polymers of different molecular weights and tacticities. Some properties of these polymers have been compared with those of a sample prepared with a special stereoregulating catalyst at the Hercules Powder Company. The proton magnetic resonance spectra of poly(methyl vinyl ether) in several solvents have been investigated and it has been possible to assign the absorptions by the methoxyl protons to particular steric configurations of the polymer chain. These data have been used to compare the tacticities of the different polymer samples and to establish that good steric control in the propagation reaction is possible with a soluble BF3 etherate catalyst.
Polymer formation through diazonium coupling
Authors: Ravve A. , Fitko C. 
Published: April 2003

AbstractPolymers were prepared through coupling of bisdiazonium salts to polyphenols. Three different polyphenols were employed for this condensation with four aromatic diamines. Products were obtained with molecular weights ranging from below 2,000 to over 20,000. In three of the four condensations carried out, no loss of nitrogen was detected through the coupling reactions, but some nitrogen appeared to have been lost in the fourth case. All polymers obtained were dark in color. The polymers possessing p‐hydroxy azo groups in their makeup occluded water which was held strongly.
ω‐Cyanothiaalkyl polyacrylates: A new class of synthetic rubbers
Authors: Prager Julianne H. , McCurdy Richard M. , Rathmann George B. 
Published: April 2003

AbstractThe synthesis and polymerization of a series of ω‐cyanothiaalkyl acrylates, CH2CHCO2(CH2)mS(CH2)nCN, are described. The length of the side chain and the position of the sulfur atom are varied. Microgelation is found to occur during polymerization, as indicated by viscosity and molecular weight measurements (for 5‐cyano‐3‐thiapentyl polyacrylate at 90% conversion: [η], 0.37 in acetone; M̄w, 600 million). Possible mechanisms of gelation are considered. Glass transition temperatures and solvent swellings are reported as follows: 4‐cyano‐3‐thiabutyl polyacrylate, Tg −24°C., 14% volume swell in benzene; 5‐cyano‐3‐thiapentyl polyacrylate, −50°C., 20% 6‐cyano‐3‐thiahexyl polyacrylate, −58°C., 38% 6‐cyano‐4‐thiahexyl polyacrylate, −58°C., 42% 8‐cyano‐7‐thiaoctyl polyacrylate, −59°C., 120%. The relation between these properties and the structure of the polymers is discussed. The swelling of 5‐cyano‐3‐thiapentyl polyacrylate in eighteen other fluids is given; an estimate (between 10 and 12.5) is made of the solubility parameter of this polymer. Bulk properties are reported for the vulcanizate of 5‐cyano‐3‐thiapentyl polyacrylate.
Copolymerization of tetrafluoroethylene with ethylene induced by ionizing radiation
Authors: Tabata Yoneho , Shibano Hiroshi , Sobue Hiroshi 
Published: April 2003

AbstractRadiation‐induced copolymerization of tetrafluoroethylene with ethylene was carried out. It was found from this investigation that the composition of copolymers varied continuously in a wide range of molar concentrations of one component. The melting point of the copolymers obtained varied continuously with the molar concentration of one component in monomer mixture between the melting points of both homopolymers. The x‐ray diffraction measurements showed that the copolymer obtained was crystalline. The copolymerization proceeds by a radical mechanism. It was concluded that both the energy transfer to ethylene from tetrafluoroethylene during irradiation and great affinity of hydrogen atom for fluorine atom would play an important role in the copolymerization.
Elemental sulfur as a plasticizer for polysulfide polymers and other polymers
Authors: Tobolsky A. V. , Takahashi N. 
Published: April 2003

AbstractIn a recent publication from this laboratory it has been shown that the so‐called elastic sulfur obtained by quick quenching molten sulfur from a temperature of 250°C. to a temperature of about −10°C. is really a mixture of polymeric sulfur and monomeric S8 sulfur, the latter in a metastable condition. The reason why quick quenched sulfur is elastic is because of the plasticizing effect of the liquid S8 sulfur on the polymeric sulfur. In this publication we show that large concentrations of S8 can exist dissolved in a liquid condition in other polymers where it also acts as a plasticizer. In many cases these compositions appear completely stable, i.e., there is no tendency for the dissolved sulfur to crystallize out. The best example is crosslinked polyethylene tetrasulfide polymers. We show that these polymers can retain 40% of dissolved sulfur in the form of liquid S8 over indefinitely long periods of time. We prove that the sulfur is in its elemental form by quantitative extraction with CS2. The specific volume of the dissolved sulfur shows it is in a liquid condition. The mechanical properties of the sulfur plasticized crosslinked polymers are just what would be expected from this type of structure. Preliminary information concerning sulfur in other polymers is presented.
The use of syton 2X colloidal silica as a calibration medium for light‐scattering photometers
Authors: Jennings B. R. , Jerrard H. G. 
Published: April 2003

AbstractDetails are given of studies made on a colloidal silica suspension known as Syton 2X. The studies were carried out to investigate the possibilities of Syton as a calibration medium for light‐scattering photometers. The requisites of a suitable calibration medium are discussed. The same studies were made on another silica suspension, Ludox, which has been much used by others for calibration and the results obtained for the two substances compared. Transmission and angular scattering properties were studied using a spectrophotometer and a light scattering photometer respectively. The calibration constant J of the latter instrument was determined using Syton and Ludox. The values obtained for J were almost identical. The instrument was used to determine the Rayleigh ratios R90 of benzene, toluene, and carbon disulfide for two wavelengths (4358 and 5641 A.). The values compare favorably with those of other workers and are considered very reliable. Weight‐average particle sizes were found with the use of an electron microscope, an analytical ultracentrifuge, and the light‐scattering and transmission data. The electron micrographs showed Ludox and Syton particles to be almost spherical. The particle diameters of Ludox were found to be 199 A. by the electron microscope, 174 A. by the ultracentrifuge, and 195 A. by light‐scattering and transmission measurements. For Syton the corresponding values were 145 A., 142 A., and 142 A., respectively. Depolarization ratios were also determined; in both cases they were small. It is concluded that provided oil‐free samples are used, Syton is a good substitute for Ludox. Its particles are smaller and the solutions are less polydisperse. It is thought that the ultracentrifuge gives low values for particle diameters and that this is possibly due to an incorrect assumption for the frictional coefficient of the sedimenting particles.
Kinetic study of the autoxidation of cellulose suspended in sodium hydroxide solution
Authors: Michie R. I. C. , Neale S. M. 
Published: April 2003

AbstractAn apparatus has been designed to measure small extents of gas absorption by a relatively large volume of liquid under conditions of vigorous agitation. With this apparatus a study has been made of the absorption of oxygen by finely divided cotton cellulose suspended in sodium hydroxide solution at 40°C. over a range of alkali concentration, cellulose content, and oxygen pressure. In one series of experiments cellulose depolymerization was also determined and in another experiment the alkaline autoxidation of β‐methyl cellobioside was followed. During the early stages the reaction is autocatalytic with alkali concentrations above 8N. In the absence of diffusion effects, that is with alkali concentrations below approximately 10N, the steady rate of oxygen absorption is given by the equation,

where [Cell] refers to the weight of cellulose immersed in the solution, [O2] the partial pressure of oxygen, aNaOH the molal activity of the sodium hydroxide, θ[M] a function of the metal ion content and K and K′ are constants. The known characteristics of the autoxidation are consistent with a modified Gee‐Bolland mechanism. Thus a cellulose radical formed as a result of peroxide decomposition reacts with oxygen to form a radical of the type \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm RO}_2^{.} $\end{document}. The last named is likely to be unstable and split off the \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm O}_2^{\bar .} $\end{document} radical ion which is comparatively unreactive but must nevertheless be capable of attacking an ionized cellulose molecule, thus completing one oxidation cycle. In principle a chain reaction could follow but the evidence indicates that a long chain mechanism is not involved, particularly at the stage of attainment of the steady rate.
Intramolecular hydride shift polymerization by cationic mechanism. II. Spectroscopic analysis of poly‐3‐methylbutene‐1
Authors: Kennedy J. P. , Minckler L. S. , Wanless G. , Thomas R. M. 
Published: April 2003

AbstractThe structures of cationically obtained poly‐3‐methylbutene‐1, isotactic poly‐3‐methylbutene‐, and hydrogenated 3,4‐polyisoprene have been investigated by nuclear magnetic resonance and infrared spectroscopy. These studies corroborate the previously proposed structure of an α,α′‐dimethylpropane repeating unit for the cationic polymer and they confirm the conventional 1,2 head‐to‐tail enchainment for the isotactic polymer and for the hydrogenated 3,4‐polyisoprene. The NMR spectra of cationic poly‐3‐methylbutene‐1 and polyisoprene are very similar and show only two peaks. They are quite different from the spectra of isotactic poly‐3‐methylbutene‐1 and hydrogenated 3,4‐polyisoprene. The isotactic product was solubilized by careful pyrolysis to render it amenable to spectroscopic studies. Unfortunately, present‐day NMR spectroscopy does not possess high enough resolution to be useful in the quantitative investigation of mixtures of 1,3 and 1,2 enchainments. The NMR spectrum of polyisobutylene oxide can be used to distinguish cationic poly‐3‐methylbutene‐1 from the isotactic modification and from the hydrogenated 3,4‐polyisoprene. The more important bands have been analyzed and assigned. Isotactic poly‐3‐methylbutene‐1 and hydrogenated 3,4‐polyisoprene both have a conventional 1,2 structure, and their infrared spectra are essentially identical.
Electron spin resonance studies of irradiated single crystals of methacrylamide
Authors: Ueda Hisashi 
Published: April 2003

AbstractIrradiated single crystals of methacrylamide were studied by electron spin resonance. Irradiations were made at 77 and 288°K. and measurements were made at 77, 193, and 293°K. Only chemical changes explain these spectra. The original scission is CC breakage between (CONH2) and CH2C(CH3), and CH breakage between CH2C‐(CONH2)CH2 and H; these small fragments react with methacrylamide and finally produce two free radicals at room temperature. These two free radicals are the ones which propagate or terminate the polymerization. The free radical transformation at the last period of polymerization is concluded to be:
Thermal degradation of poly(m‐diethynylene benzene)
Authors: Newkirk A. E. , Hay A. S. , McDonald R. S. 
Published: April 2003

AbstractPowdered poly(m‐diethnylene benzene) can be dissolved in hot nitrobenzene, and thin clear sheets having a yellow color and a tensile strength approaching 9000 psi can be cast from this solution. When the polymer powder is heated rapidly in vacuo, it explodes gently at about 180°C. to yield carbon, but it can be annealed at 150°C. and then heated to form carbon without the explosive reaction. The major gaseous decomposition products of the explosive reaction are methane and hydrogen. The polymer film can be crystallized in tetrahydrofuran and shows excellent spherulitic growth. The crystalline film as well as aged noncrystalline film degrades when heated rapidly, but without explosive decomposition. Some indication of the mechanism of decomposition is provided by infrared studies of the film pyrolyzed at 100°C. intervals to 600°C. X‐ray diffraction studies show that the polymer may exist in amorphous and crystalline forms In the amorphous form, the diffraction maximum indicates an average interchain separation of 4.28 A., substantially less than for other polymers. Chars prepared by heating the polymer give diffraction patterns similar to those for amorphous carbon blacks. A related substance, poly(p‐diethynylene benzene), is an intractable crystalline powder having a hexagonal unit cell, a0 = 7.74 A., c0 = 8.97 A., containing three monomer units.
Radiation‐induced copolymerization of tetrafluoroethylene with propylene at low temperature
Authors: Tabata Yoneho , Ishigure Kenkichi , Sobue Hiroshi 
Published: April 2003

AbstractRadiation‐induced copolymerization of tetrafluoroethylene with propylene was carried out at low temperature in the liquid phase. The resulting copolymers were found to range from viscous oils to rubberlike materials, depending on the polymerization conditions. It was observed that there are induction periods in these copolymerizations, and that the rate of copolymerization is proportional to the square root of the dose rate. Fluorine contents of the copolymers were determined, and the monomer reactivity ratios in the copolymerization were found to be rC3H6 = 1.0 and rC2F4 = 0.06. The viscosity of the copolymer was measured in tetrahydrofuran at 30°C. Infrared spectra of the copolymers were also measured. It was concluded from these experimental results that the copolymerization proceeds by a radical mechanism.
Heterophase polymerization of 4‐ vinylpyridine with butyllithium
Authors: Spiegelman P. P. , Parravano G. 
Published: April 2003

AbstractThe butyllithium‐initiated polymerization of 4‐vinylpyridine in hydrocarbon media proceeded by an anionic addition mechanism. The colorless, soluble reactants rapidly formed a granular, intensely colored, polymer precipitate at temperatures below −30°C. in heptane and toluene diluents. When the reaction was carried out in an impurity‐free environment, the highly colored reaction mixture remained unchanged for indefinite periods of time, and further addition of monomer produced continued growth of polymer chains. A dilatometric technique was employed to follow the rate of polymerization in toluene media. The experimental methods that were used for manipulation of solutions in vacuo resulted in polymerization (30–50% conversion) during an initial unsteady temperature period followed by a constant temperature interval during which rate measurements were obtained. Initial monomer and initiator concentrations were varied over a fourfold range. Rate measurements were made in the temperature interval −30°C. to +30°C. The dilatometric kinetic experiments together with additional, independent observations established that the rate was proportional to monomer concentration, and to the one half power of the initiator concentration, suggesting an equilibrium complex formation of growing polymeric anions. Rate constants were computed from the values of the rates obtained from the dilatometric kinetic experiments and the square root of the effective initiator concentration. A calculation of the temperature dependence of the rate constants produced an activation energy of 12.7 kcal./mole. As predicted by anionic polymerization theory, the polymer formed in these reactions had a number‐average molecular weight equal to the ratio, (weight of polymer)/(equivalents of initiator). The polymer was fractionated by elution chromatography with tert‐butyl alcohol and benzene solvent–nonsolvent mixtures. The molecular weight distributions of the polymer, constructed from fractionation data, showed a bimodal distribution in two fairly narrow molecular weight ranges. This uncommon molecular weight distribution is due to occlusion of a portion of the active growing chain ends in the polymer precipitate. These trapped reaction sites (which in these experiments amounted to 95% and up of the total initiator concentration) no longer produced chain growth due to the absence of available monomer. The remaining “effective” reaction sites thus grow to high molecular weight and are responsible for the observed kinetics.
α–γ Transition of nylon 6
Authors: Arimoto H. 
Published: April 2003

AbstractThe mechanism of the α‐γ transition of nylon 6 due to iodine treatment and the structure of the γ‐form of nylon 6 are discussed on the basis of results of x‐ray diffraction and polarized micro‐infrared absorption measurements on doubly oriented and iodine‐treated specimens. The plane of the amide group and that of the methylene group are both parallel to the rolled plane, which is parallel to the hydrogen‐bonded molecular sheet in the α‐form of nylon 6. The plane of the amide group is preferentially twisted to a direction roughly perpendicular to the rolled plane on coordination of iodine to the oxygen of the amide group and this preferential orientation of the amide group is retained on the removal of iodine. The preferential orientation of the amide group in the molecule supports the pleated sheet structure proposed by Kinoshita for the γ‐form of polyamides. Infrared bands are examined, the preferential orientation of the amide group being taken into account. The structure of the γ‐form of nylon 6 is composed of pleated sheets of similarly directed molecular chains joined by hydrogen bonds between the adjacent molecules and in such a packing of sheets the directions of molecular chains are alternately inverse along the direction of stacking of sheets.
Investigation of the stereoregularity of poly(vinyl alcohol)
Authors: Fujii Kiyoshi , Mochizuki Takani , Imoto Saburo , Ukida Junji , Matsumoto Masakazu 
Published: April 2003

AbstractStudies of the steric structures of poly(vinyl alcohol), as deduced from studies of the structures of its esters, particularly poly(vinyl formate) are described. Two types of tactic poly(vinyl formate) crystallize with different structures, corresponding to their different molecular structures. Therefore, the type of molecular stereoregularity in poly(vinyl formate) samples can be deduced from an examination of the crystals produced by a given crystallization treatment. From the results of the study of the poly(vinyl formate) crystals, some conclusions can be drawn concerning the steric structure of poly(vinyl alcohol). Crystallizabilities of other tactic poly(vinyl esters) have also been investigated.
Copolymerization of tetrafluoroethylene with isobutene induced by ionizing radiation
Authors: Tabata Yoneho , Ishigure Kenkichi , Oshima Keichi , Sobue Hiroshi 
Published: April 2003

AbstractRadiation‐induced copolymerization of tetrafluoroethylene with isobutene was carried out in the liquid state of the monomers at low temperature. The composition curve of the tetrafluoroethylene–isobutene copolymer was obtained. Infrared spectra, x‐ray diffraction, and melling points of the copolymers obtained were also measured. It was concluded from these experimental results that an alternating crystalline isobutene tetrafluoroethylene copolymer can be obtained by a radical process induced by ionizing radiation. This seems to be the first case in which an alternating crystalline copolymer was obtained by a radical mechanism over an extremely wide range of molar concentration of the components in the monomer mixture.
Preparation and polymerization of vinyl esters of cyclic and polychloro fatty acids
Authors: Marvel C. S. , Hill J. C. , Cowan J. C. , Friedrich J. P. , O'Donnell J. L. 
Published: April 2003

AbstractHomopolymers and vinyl chloride copolymers have been prepared from the vinyl esters of mixed hydrogenated cyclized linolenic acid, 9,10‐dichlorostearic acid, 9,10,12,13‐tetrachlorostearic acid, 13,14‐dichlorobehenic acid, 9(10)‐phenylstearic acid and technical behenic acid. Vinyl 13,14‐dichlorobehenate (29%)‐vinyl chloride (71%) gave a copolymer with a brittle temperature of ‐2°C. All of the other copolymers with vinyl chloride had brittle temperatures of 16°C. or higher and behaved more like rigid plastics.