bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of chemical reagents on the fine structure of cellulose. Part I. Action of diazomethane
Authors: Spedding H. , Warwicker J. O. 
Published: April 2003

AbstractAn infrared and x‐ray study of the action of diazomethane on the fine structure of ramie and regenerated cellulose (fiber and film) has been made. It has been found that the methylation process affects the disordered regions, and also parts of the structure that are sufficiently highly ordered to be detected by x‐ray methods but whose hydrogenbond order is too low to be detected by the infrared‐deuteration technique. The effect of partial methylation on the hydrogen bonding in the noncrystalline regions is described and discussed. The conclusion drawn from the results is that diazomethane can react in the noncrystalline and the imperfectly crystalline regions, but not in the highly ordered crystalline regions.
Studies in condensed phosphates. Part VII. Metachromatic reactions of sodium polymetaphosphate and its derivatives
Authors: Mehrotra R. C. , Gupta V. S. 
Published: April 2003

AbstractMetachromatic behavior of the complex metaphosphates is almost identical to that of Graham's salt and is quite different from that of either simple or mixed trimeta‐ or other lower phosphates. With toluidine blue, the wavelength of maximum absorption shifts from 630 to 530 mμ in all the above cases. Addition of calcium or barium chlorides did not show any change in the optical density or wavelength of maximum absorption except at 4.0 × 10−4M barium chloride concentration.
Cyclo‐ and cyclized diene polymers. I. Polymerization of conjugated dienes to ladder cyclo‐polymers with complex catalysts
Authors: Gaylord N. G. , Kössler I. , Štolka M. , Vodehnal J. 
Published: April 2003

AbstractPolymerization of isoprene, butadiene, and chloroprene with complex catalysts consisting of alkyl or arylmagnesium bromide or triethylaluminum and excess TiCl4 leads to the formation of powdery, insoluble, probably crosslinked polymers with high density and high heat resistance (>370°C). The structure of these polymers differs from that of those prepared at higher molar ratios of organometallic compound to titanium tetrachloride. The infrared analysis of the powdery polymers and comparisons with the spectra of cyclized 3,4‐polyisoprene and cyclized 1,4‐cis‐polyisoprene indicate that the polymer chain consists of fused six‐membered saturated rings in the form of a linear ladder or spiral ladder structure. The residual linear segments with 1,4 units, present in the predominantly cyclic polymers, may be isomerized to a cyclic form by the action of H2SO4. Removing the linear segments from the polymer chain further improves the heat resistance. It is proposed that the cyclic structure is formed during the polymerization from 1,2‐polymer and not as a result of the action of catalyst components on primarily formed linear chains. The cyclic structure may be ascribed to all three investigated polymers.
Polymerization of chlorinated diphenylsiloxanes
Authors: Ganci James B. , Bettelheim Frederick A. 
Published: April 2003

AbstractChlorinated diphenylsiloxanes were prepared by acid‐ and base‐catalyzed polymerization of the corresponding diols in polar organic solvents. Under mild conditions, cyclic tetramers were isolated. More forcing conditions in the presence of base yielded resins containing largely cyclic species which showed extensive cleavage of the phenyl groups. The order of the phenyl group cleavage among the polymers indicated that the inductive effect of the substituent halogen plays a dominant role.
Thermal stability of the copolymer of sulfur dioxide and cis,cis‐1,5‐cyclooctadiene
Authors: Frazer A. H. 
Published: April 2003

AbstractThe copolymer of sulfur dioxide and cis,cis‐1,5‐cyclooctadiene has been synthesized under a variety of conditions and pyrolyzed. Degradation of this copolymer followed first‐order kinetics to a first approximation at 220°C. or above. Random cleavage of the polymer chain accompanied the pyrolysis as it was carried out in these experiments. Pyrolysis of the copolymer up to 75% loss of weight yielded the monomers as cracking products and in the mole ratio of the copolymer composition.
Experimental data on dilute polymer solutions. Hydrodynamic properties and statistical coil dimensions of poly(n‐butyl methacrylate). Part II
Authors: Van Leemput R. , Stein R. 
Published: April 2003

AbstractViscometric measurements were carried out on poly(n‐butyl methacrylate) fractions in chloroform, benzene, toluene, and dioxane. Light‐scattering and viscometric measurements on these fractions were carried out in isopropanol over a narrow range of temperatures. The Flory‐Fox Θ‐temperature was obtained by graphical interpolation on a plot of the second virial coefficient versus the reciprocal of the absolute temperature. Values of Φ, calculated according to the Flory‐Fox equation were found to be abnormally low, notwithstanding the application of heterodispersity corrections, a mean value of 1.62 × 1023 being found in isopropanol in the temperature range investigated. The dependence of [η] on the mean radii of gyration is found to be less than that predicted by the Flory‐Fox theory. The light‐scattering dimensions systematically appear to be too large in the ideal solvent, a discrepancy that cannot be explained by accumulated experimental factors.
Density gradient centrifugation of a graft copolymer
Authors: Ende H. A. , Stannett V. 
Published: April 2003

AbstractA well‐defined graft copolymer of polystyrene and cellulose acetate has been investigated using the density gradient ultracentrifugation method. The initial sample showed two peaks. These were found to be pure graft copolymer and polystyrene; the latter was easily removed by further extraction of the mixture with benzene. The composition of the graft copolymer was determined from the buoyant densities of the graft and the two homopolymers and found to be 49% polystyrene, 51% cellulose acetate compared with 44.1 and 55.9%, respectively, estimated from the weight loss after acid hydrolysis.
The effect of simultaneously occurring processes on the course of polymer crystallization
Authors: Banks W. , Sharples A. , Hay J. N. 
Published: April 2003

AbstractThe possibility that simultaneously occurring processes may account for the anomalous fractional values of the Avrami exponent found in recent polymer crystallization experiments is considered, and, on balance, rejected. A more likely explanation is that one of the assumptions used in deriving the Avrami equation is at fault. This leads to the conclusion that the Avrami parameters cannot be used diagnostically to provide information on crystallization mechanism, as has been considered to be the case in the past.
Fracture processes in polymeric materials. V. Dependence of the ultimate properties of poly(methyl methacrylate) on molecular weight
Authors: Berry J. P. 
Published: April 2003

AbstractThe influence of molecular weight on the fracture surface energy, Young's modulus, tensile strength, and inherent flaw size in poly(methyl methacrylate) has been determined. In common with other mechanical properties, the dependence of the fracture surface energy on molecular weight can be represented by γ = A – (B/M), where M is the molecular weight, and A and B are arbitrary constants. By extrapolation, the upper limiting value is 1.55 × 105 ergs/cm.2, while the surface energy, and hence the tensile strength, should become zero for a polymer of molecular weight 25,000. This value is in good agreement with that found directly from brittle strength measurements.
X‐ray‐induced polymerization of diphenylvinylphosphine oxide
Authors: Allcock H. R. 
Published: April 2003

AbstractDiphenylvinylphosphine oxide was polymerized in the molten state by x‐irradiation to give polymers with molecular weights up to 10,000. The results of variations in total radiation dose, dose rate, and temperature, are consistent with a free radical polymerization mechanism in which chain transfer is important. Infrared spectra of the polymers provided evidence that phenyl groups are involved in the chain transfer processes.
Kinetic study of the polymerization of α‐d‐styrene and/or styrene by homogeneous catalysis. Part I
Authors: Overberger C. G. , Diachkovsky F. S. , Jarovitzky P. A. 
Published: April 2003

AbstractIncreases in the rates of polymerization of α‐d‐styrene and/or styrene by homogeneous catalysis with the (C5H5)2TiCl2–Al(C2H5)2Cl catalyst system were shown to be directly proportional to the α‐d‐styrene monomer concentration. These rate increases were explained by an increase in the concentration of active centers. Polymer intrinsic viscosities were shown to be independent of the α‐d‐styrene monomer concentration. Changes in the polymerization rates were correlated with observed changes in the catalyst composition measured spectrophotometrically. A scheme is suggested to explain the observed results.
Configuration and hydrodynamic properties of fully acetylated guaran
Authors: Koleske Joseph V. , Kurath Sheldon F. 
Published: April 2003

AbstractFully acetylated guaran, (guaran triacetate, GTA), was fractionated and the fractions in the weight‐average degree of polymerization range of 171 to 12,400 were characterized by light scattering and viscometry. At high molecular weights, non‐Newtonian flow was observed and after appropriate correction the intrinsic viscosity was found to be independent of shear gradient. Analysis of viscosity results according to the theory of Kurata and Yamakawa indicated that at high molecular weights the molecule is nondraining and that excluded volume effects are absent. Polymolecularity was estimated from ultracentrifuge and osmotic pressure measurements on certain key fractions and in the case of one fraction it was possible to determine the distribution of molecular weights and to demonstrate the validity of the Zimm‐Schulz distribution. The ratio of the mean square radius of gyration to the molecular weight was found to decrease with increasing molecular weight indicating a non‐Gaussian behavior that cannot be accounted for by the Porod‐Kratky chain model. The dependence of radius of gyration on chain length is identical to that observed for hydroxyethyl cellulose and cellulose tricaproate indicating that the β‐1,4‐linked D‐glucose chain of cellulose and the β‐1,4‐linked chain of GTA have similar configurations, in spite of chemical and structural differences between the anhydro sugar units. The α‐1,6‐linked D‐galactose side groups on every other mannose unit of GTA do not appear to affect main chain configurations to any great extent. Equivalent bond lengths calculated from intrinsic viscosity and from light scattering indicate that it is necessary to distinguish between the hydrodynamic and light‐scattering radius of gyration The Flory coefficient calculated from the light‐scattering radius of gyration was found to increase with increasing molecular weight. When the hydrodynamic radius of gyration was used in the calculation, agreement with the theoretical Flory constant was within experimental error.
Calculation of copolymerization reactivity parameters from product probabilities
Authors: Ham George E. 
Published: April 2003

AbstractThe premise is examined that there exists for each monomer in copolymerization a reactivity parameter p, such that a product probability may be calculated for any combination of three monomers in binary or ternary polymerization, where = Pab‐PbcPca = PacPcbPba. The consistency of this equation and its derived equation, r12r23r31 = r13r32r21, with the Q–e scheme is demonstrated. Simplified equations are presented relating monomer and copolymer composition for any number of monomers: a/b = Pba/Pab, a/c = Pca/Pac,…, up to a/j = Pja/Paj, where j is the final component in the copolymerization and each probability includes possibilities of reaction of a given radical with monomers a–j.
Prediction of ionic copolymerization reactivity ratios
Authors: O'Driscoll Kenneth F. 
Published: April 2003

AbstractIt is shown that it is possible to predict the reactivity ratios for the copolymerization of a given monomer pair if each monomer has been separately copolymerized with a third monomer, and the product of the reactivity ratios of one of these separate copolymerizations is equal to unity. This latter condition is frequently met in ionic copolymerizations and is sometimes true in free radical copolymerizations. Literature data for five trios of monomer are examined to show the validity of the predictions.
Kinetics and mechanism of the trialkylboron‐catalyzed polymerization of methyl methacrylate in the presence of oxygen
Authors: Hansen Richard L. 
Published: April 2003

AbstractThe rate of the bulk polymerization of methyl methacrylate catalyzed by triethylboron‐oxygen was investigated. The rate was studied as a function of initial triethylboron and oxygen concentrations as well as temperature. The effect of hydroquinone was determined. The polymerization rate was also investigated using several other trialkylboranes. The initial rate of the triethylboron‐catalyzed polymerization was found to depend on the square root of the oxygen concentration and on the square root of the difference between the triethylboron and oxygen concentrations. The rates at higher conversions were consistent with an initiation mechanism requiring consideration of reactions at all three boron–carbon bonds. An initiation mechanism involving oxidation to peroxide followed by a reduction utilizing unoxidized boron–carbon bonds is advanced. Ethyl radical, produced in this reduction, is the initiating species. The overall activation energy taken from initial rates was 2.4 ± 0.3 kcal./mole in the range 0–45°C. A very slow polymerization with triethylboron was observed in the absence of oxygen. Hydroquinone behaved as a typical inhibitor for the aerobic polymerization but did not inhibit the polymerization in the absence of oxygen.
Ionic copolymerization of styrene and p‐methylstyrene
Authors: Phillips B. D. , Hanlon T. L. , Tobolsky A. V. 
Published: April 2003

AbstractThe copolymerization of styrene and p‐methylstyrene has been initiated by Friedel‐Crafts metal halides, benzoyl peroxide, a Ziegler catalyst from triethylaluminum and titanium tetrachloride, alkali metal dispersions, and alkali metal‐naphthalene complexes in a variety of polar and nonpolar solvents. The composition of the initial copolymer from an equimolar monomer mixture was used as the basis for comparison of these systems. By a suitable choice of initiator and solvent, the copolymer composition was varied within the range 25–79 wt.‐% styrene. Cationic catalysts yield copolymers with low styrene contents while anionic and electron transfer initiator produce copolymers with high styrene contents. The compositions of the initial copolymers are briefly discussed in relation to the ionic character of the growing polymer–gegenion ion pair and the polarity of the reaction medium.
Polymerization in liquid sulfur dioxide. Part XXII. Comparison of retarding effects of bases on the radical polymerization of acrylonitrile in liquid sulfur dioxide
Authors: Matsuda Minoru , Tokura Nichiro 
Published: April 2003

AbstractThe radical polymerization of acrylonitrile was carried out in liquid sulfur dioxide and in benzene, with addition of aniline, dimethylaniline, dimethyl‐0‐toluidine, and diethylaniline to these systems. The temperatures of polymerization were 40, 50, and 60°C. It was found that the chain transfer reaction occurs more easily in liquid sulfur dioxide than in benzene; this was attributed to the differences in the polarity of the terminal radical of the growing chain in both solvents. The difference of activation energies due to the difference of bases is not so large. The frequency factors are rather important in both solvents for chain transfer reactions. The isokinetic relation is also discussed.
Homopolymers and terpolymers of 5,7‐dimethyl‐1,6‐octadiene
Authors: Wilbur J. M. , Marvel C. S. 
Published: April 2003

AbstractPolymerization of 5,7‐dimethyl‐1,6‐octadiene with a 2/1 molar ratio of triisobutylaluminum/vanadium oxychloride, triisobutylaluminum/titanium tetrachloride or triisobutylaluminum/vanadium tetrachloride affords an elastic homopolymer. Attempted polymerization of the isomeric 3,7‐dimethyl‐1,6‐octadiene under the same conditions failed. Elastomeric terpolymers of ethylene, propylene, and 5,7‐dimethyl‐1,6‐octadiene have been prepared with these same coordination catalysts.
Endgroup studies in persulfate‐initiated vinyl polymer by dye techniques. Part I. Initiation by persulfate alone
Authors: Ghosh Premamoy , Chadha Subhash Chander , Mukherjee Asish R. , Palit Santi R. 
Published: April 2003

AbstractQuantitative determination of endgroups of poly(methyl methacrylate), polystyrene and poly(vinyl acetate) obtained by aqueous initiation with K2S2O8 under varied conditions have been made by the application of two sensitive dye techniques, called the dye partition technique and the dye interaction technique. The description of the dye techniques are given in detail. Sulfate (OSO3−) and hydroxyl (OH) endgroups are generally found to be incorporated in the polymers to an average total of 1.5 to 2.5 endgroups per polymer chain. Hydroxyl endgroups are always present to a fairly large extent. The proportion of sulfate endgroups in polymers is highly dependent on the pH of the polymerizing medium; it increases with the alkalinity of the medium and sharply decreases under acid conditions.
Copolymerization of 4‐cyclopentene‐1,3‐dione with acrylonitrile and methyl methacrylate
Authors: Hamb F. Lynn , Winston Anthony 
Published: April 2003

AbstractThe copolymerization of acrylonitrile and methyl methacrylate with 4‐cyclopentene‐1,3‐dione (M2) is reported. The copolymers were prepared by heating the monomer feeds in sealed tubes with α,α′‐azobisisobutyronitrile. Infrared bands for both the β‐diketone and the nitrile, in the case of acrylonitrile, or ester, in the case of methyl methacrylate, indicated that copolymerization had occurred. The acrylonitrile copolymers were insoluble in the common solvents and swelled on treatment with dimethylformamide and dimethylsulfoxide. The methyl methacrylate copolymers were partially soluble in the usual solvents with the solubility and gel content varying with the composition of the copolymers. Solution viscosities indicated high molecular weights. The reduced specific viscosity of the sodium salt of the 0.05 methyl methacrylate copolymer increased with decreasing concentration, a characteristic typical of polyelectrolytes. The compositions of the copolymers were determined from the nitrogen analyses for acrylonitrile copolymers, and the ultraviolet absorption of the β‐diketone for the methyl methacrylate copolymers. The molar extinction coefficient of the β‐diketone structural unit was estimated from a study of model compounds. The reactivity ratios were evaluated by the usual methods. For the acrylonitrile (M1)–4‐cyclopentene‐1,3‐dione (M2) system, r1 = 3.67, r2 = 0.21. For the methyl methacrylate (M1)–4‐cyclopentene‐1,3‐dione (M2) system r1 = 7.4, r2 = 0.083. For each system Q and e values for 4‐cyclopentene‐1,3‐dione were evaluated. The average values are Q = 0.20, e = 1.42. The behavior of 4‐cyclopentene‐1,3‐dione is compared with maleic anhydride and N‐butylmaleimide with respect to the reactivity of the monomer, the reactivity of the radical, and the effective polarity of the double bond.
Molecular configuration and hydrodynamic behavior of poly‐N‐tert‐butylacrylamide in methanol
Authors: Jennings B. R. , Jerrard H. G. 
Published: April 2003

AbstractThe results of a light‐scattering study of six samples of poly‐N‐tert‐butylacrylamide in methanol are presented. Some confirmatory results have been obtained with the use of an ultracentrifuge. The derivation of molecular parameters from Zimm plots and centrifugation data is briefly described. Methanol is found to be a good solvent for poly‐NTBA, in which it behaves as a stiff molecule expanded beyond random flight predictions. The effect of the stiffness on the Zimm plots and on the interpretation of the results is discussed. Values of the weight‐average and number‐average molecular weights (M̄w and M̄n), the z‐average and number‐average radii of gyration (pz2)1/2 and (pn2)1/2 and the corresponding end‐to‐end distances (rz2)1/2 and (pn2)1/2 are found. r2 = 161N̄, where N is the degree of polymerization and r̄ is measured in Angstroms. Values are also obtained for the length of the statistical element, the Kratky‐Porod persistence length, the coiling factor, the molecular expansion factor, the second osmotie virial coefficient, (A2), and the Flory constants Φ and Kv. Equations for the variation of (pn2)1/2 and of A2 with molecular weight are derived: they are (pn2)1/2 = 3.76 × 10−9 M̄n−0.515 and A2 = 0.082 M̄w−0.515, respectively. The value of Φ is considerably less than that normally predicted, and possible reasons for this are suggested. Empirical relations involving the excluded volume effect are mentioned.
Polymerization of acetaldehyde. Part V. Polyaldol condensation of acetaldehyde by alkali metal amalgam as catalyst. II
Authors: Imoto Tatsuya , Matsubara Tsutomu 
Published: April 2003

AbstractIn a previous paper, it was reported that an acetaldehyde polymer of the poly‐(vinylalcohol) type was obtained by polymerization of acetaldehyde with sodium amalgam as catalyst. In the present, more detailed investigation, it was found that the catalyst concentration, the reaction time, the reaction temperature, and the solvent concentration have certain effects on the molecular weight and the yield of polymer. At the early stage of this polymerization, the yield is proportional to the square root of the reaction period. So, at this stage, the reaction may be assumed to be diffusion‐controlled. Several solvents and the two‐stage polymerization have influences upon this polymerization.
Polymerization of higher aldehydes. IV. Crystalline isotactic polyaldehydes: Anionic and cationic polymerization
Authors: Vogl O. 
Published: April 2003

AbstractLow temperature polymerization of aldehydes in solvents of low dielectric constants yields crystalline isotactic polyaldehydes. Alkali metal alkoxides were found to be the best initiators; but alkali metals, alkali metal alkyls, Grignard reagents, lithium aluminum hydride, and aluminum organic compounds also work effectively. Isotactic polyaldehydes were also obtained by cationic initiation (stannic bromide, solid BF3 etherate). The stereoregularity increases with the increase of the space requirements of the side chain.
Electron transfer polymers. XXIII. Interactions of the quinhydrone type in polyvinylhydroquinone solutions
Authors: Kamogawa Hiroyoshi , Giza Yueh‐Hua Chen , Cassidy Harold G. 
Published: April 2003

AbstractAn investigation was made of the pink‐orange color that reaches maximum intensity at the midpoint of the titration of homopolymers of vinylhydroquinone. It was shown that during oxidative titration the hydroquinone absorption at 295 mμ decreases in intensity while quinone absorption at 254 mμ, increases. At the midpoint of the titration absorption at approximately 455 mμ, the pink color, reaches its maximum intensity, with relatively low extinction coefficient. The position of the maxima does not change with extent of oxidation; the specific extinction coefficient is independent of concentration and degree of polymerization, but somewhat dependent on the nature of the solvent. When the functional groups were somewhat separated along the chain by copolymerization with an alternating comonomer, styrene, α‐methylstyrene, or acrylamide, there was no appreciable shift in the ultraviolet absorption peaks with oxidation, but in the visible region the intensity at 455 mμ was greatly decreased, compared with homopolymer, at all degrees of oxidation around the midpoint. Analysis of the spectroscopic data led to the conclusion that the number of quinhydronelike interactions is low relative to the number of groups that are not interacting.