bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soluble homopolymers and copolymers from 2,6‐disubstituted‐1,6‐heptadienes
Authors: Milford G. N. 
Published: April 2003

AbstractA method is described for the preparation of high molecular weight, soluble homopolymers from 2,6‐disubstituted‐1,6‐heptadienes. Contrary to expectation, the disubstituted heptadienes readily form soluble, high molecular weight copolymers with vinyl‐ and acrylate‐type monomers if dilute solutions are employed and polymerization is not too rapid. The absence of unsaturation in copolymers and their excellent solubility indicates that the disubstituted heptadienes polymerize by an intramolecular‐intermolecular mechanism even in the presence of reactive monomers.
Molecular weight distribution of anionically polymerized α‐methylstyrene
Authors: McCormick Herbert W. 
Published: April 2003

AbstractThe molecular weight distribution of anionically polymerized α‐methylstyrene has been measured by sedimentation velocity analysis. Molecular weight dependence of sedimentation constants and solution viscosities are reported. It is shown that the molecular weight distribution of poly‐α‐methylstyrene made by sodium complex is very narrow. Formation of a two‐peaked distribution polymer is reported; the data give support to the mechanism of double‐ended polymer propagation.
Ch2‐rocking vibrations and structural correlations of poly(ethylene glycols)
Authors: White Horace F. , Lovell Channing M. 
Published: April 2003

AbstractInfrared absorption spectra of ethylene glycol and various higher molecular weight poly(ethylene oxides) have been obtained both in the liquid and solid phases. The similarity of the solid and liquid phase spectra for the poly(ethylene oxides) suggest that these materials exist in essentially the same conformation (gauche) in both phases. The disappearance of a band similar to one in liquid ethylene glycol with increasing molecular weight suggests a molecular weight dependence of a trans conformation. Oriented high molecular weight poly(ethylene oxide) spectra are consistent with recent x‐ray diffraction studies.
Alkaline hydrolysis of methacrylic acid–ester copolymers
Authors: Smets G. , de Loecker W. 
Published: April 2003

AbstractThe alkaline hydrolysis of six different copolymers of methacrylic acid and methyl methacrylate having acid contents of 28.9, 49.5, 58.5, 66, 72, and 83 mole‐% was studied. At pH values smaller than 12.5 the reaction mechanism is principally intramolecular, as a result of neighboring acid‐ester group interactions. Both the chemical composition and the stereochemical configuration of the polymers exert a strong influence on the course of the reaction. In strongly alkaline medium, the hydrolysis results primarily from the external action of hydroxyl ions, except in the case of a copolymer containing 83 mole‐% acid, in which the reaction again results essentially from an intramolecular mechanism.
The copolymerization characteristics of vinylene carbonate, γ‐crotonolactone and methyl bicyclo(2,2,1)‐2‐heptene‐5‐carboxylate
Authors: Judge Joseph M. , Price Charles C. 
Published: April 2003

AbstractThe copolymerization of three cyclic vinylene monomers has been investigated. For vinylene carbonate, we found Q = 0.005, e = −0.8, and for methyl bicyclo(2,2,1)‐2‐heptene‐5‐carboxylate, Q = 0.02, e = 0.0. A convenient preparation of γ‐crotonolactone is reported, but no satisfactory copolymerization for this material was found.
Allyl polymerization. V. Effective chain transfer in the polymerization of 3‐buten‐2‐‐yl acetate. Polymerization of 3‐buten‐2‐‐ol
Authors: Gaylord Norman G. , Kujawa Francis M. 
Published: April 2003

AbstractThe bulk polymerization of 3‐buten‐2‐yl acetate with benzoyl peroxide as catalyst at 80°C. is characterized by degradative and effective chain transfer. Effective chain transfer constitutes 86% of the total transfer reactions. The polymerization results in a polymer with a DP of 2.8, independent of initial catalyst concentration, and in any given polymerization the disappearance of monomer is a linear function of the disapperance of peroxide, i.e., dM/dC is constant, and decreases linearly with increasing catalyst concentration, extrapolating to 38.1 at zero catalyst concentration. The values of dM/dC and conversion to polymer are higher with 3‐buten‐2‐yl acetate than with allyl acetate. The polymer from the α‐methylallyl ester contains approximately one double bond for every three monomer units at 2% peroxide concentration. The decomposition of benzoyl peroxide in 3‐buten‐2‐yl acetate is more rapid than in the allyl ester and is characterized by considerable induced decomposition. The decomposition of peroxide in methyl vinyl carbinol is extremely rapid and the conversion of monomer to polymer is very low.
Nuclear magnetic resonance and molecular motion in polymethyl acrylate, polymethyl methacrylate, and polyethyl methacrylate
Authors: Sinnott K. M. 
Published: April 2003

AbstractThe proton magnetic resonance in polymethyl acrylate, polymethyl methacrylate, and polyethyl methacrylate has been studied between 77 and 400°K. The second moments of the absorption lines are compared with the values calculated for some of the modes of molecular motion possible in these polymers. This comparison leads to the conclusion that motion of the ester methyl and ethyl groups in the respective polymers occurs below 77°K. and that motion of the main chain methyl groups in polymethyl methacrylate and polyethyl methacrylate occurs above 130°K. This interpretation of the results is shown to be in agreement with previous measurements of the mechanical and dielectric properties of these polymers. The shape of the absorption line observed in polymethyl methacrylate at 77°K. was reproduced by a suitably weighted superposition of the absorption lines of rigid and rotating methyl groups and a rigid methylene group confirming that motion of one methyl group occurs below 77°K. in polymethyl methacrylate.
Ultrasonic degradation of polystyrene. Part 1. A proposed mechanism for degradation
Authors: Gooberman G. 
Published: April 2003

AbstractThe ultrasonic degradation of macromolecules can be considered to be caused by the rapid pressure changes accompanying the shock wave radiated from a collapsed cavity. Assuming that all the cavities are identical and that the shock wave is similar to that generated by an underwater explosion of TNT, rate constants for the degradation of polystyrene in benzene have been found as a function of molecular weight. The variation in the limiting molecular weight with ultrasonic intensity has been calculated and shown to agree with that obtained experimentally. The theory indicates that the maximum pressure reached during the collapse of a cavity is about 1600 atm.
The ferrous chelates of polyaminocarboxylic acids as initiators in the emulsion polymerization of styrene. I
Authors: Bond Joan , Jones T. I. 
Published: April 2003

AbstractThe ferrous iron–ethylenediaminetetraacetic acid–hydrogen peroxide‐initiated emulsion polymerization of styrene has been investigated, potassium palmitate being used as emulsifying agent. It was found that there was acritical concentration of iron, 0.01 part of ferrous iron per 100 parts of monomer, above which the zero‐order rate of polymerization was not appreciably increased. The rate is also proportional to the square root of the hydrogen peroxide concentration and to the soap concentration to the 0.6 power.
The ferrous chelates of polyaminocarboxylic acids as initiators in the emulsion polymerization of styrene. II
Authors: Bond Joan , Jones T. I. 
Published: April 2003

AbstractThe polyaminocarboxylic acids, ethylenediaminetetraacetic acid (EDTA), methylethylenediaminetetraacetic acid (MeEDTA), diethylenetriaminepentaacetic acid (DTPA), and cyclohexanediaminetetraacetic acid (CDTA) have been used to chelate the iron in the system ferrous iron–hydrogen peroxide when it is used as an initiator for the emulsion polymerization of styrene. In each case, the zero‐order rate of polymerization decreased from pH 0.5, when it was identical to that in the absence of any chelating agent, to a minimum value in the pH region 3.5–6.5, after which it rose again. In acid solution the results are not the same as those anticipated from the redox potentials of the ferrous–ferric–chelating agent system at various pH values, and this has been found to be due to the dissociation of the iron chelate at a low pH.
The statistical analysis of polymer fractionation data. Part I
Authors: Booth C. , Beason L. R. 
Published: April 2003

AbstractThe analysis of simple successive polymer fractionation data by conventional and statistical methods is discussed. The fractionation model originating in the Flory‐Huggins theory of polymer solutions is used to test the alternative methods. The direct statistical methods are shown to be superior to alternative procedures. Such methods approximate the individual fraction distributions by simple statistical distributions (binomial or generalized exponential), the parameters of which are calculated directly from a knowledge of two average molecular weights (M̄n and M̄w).
Stereospecificity and electric polarization in high polymers
Authors: Bacskai R. , Pohl H. A. 
Published: April 2003

AbstractThe electric polarization of a polymer is shown to depend upon the steric order along the chain. This is in accord with the previously observed electric polarization behavior of diastereomers. Solution measurements of the molar polarization of polymethyl methacrylates in benzene gave values of 32 ± 0.5 cc./mole for syndiotactic, and 41 ± 0.5 cc./mole for isotactic material, with atactic polymer showing intermediate values. It is believed therefore that the polarizability method can form a means of differentiating and interpreting the behavior of polar stereospecific polymers.
Molecular weight distribution in anionic polymerization involving a chain transfer to monomer
Authors: Litt M. , Szwarc M. 
Published: April 2003

AbstractPolymerization involving a chain transfer to monomer but not involving a termination step was discussed. Such a polymerization produces a mixture of dead and living polymeric molecules, and the resulting molecular weight distribution was calculated both for polymers initiated on one end and those initiated on both ends. The results permit calculation of number and weight average degree of polymerization. Application of these results to polymerization of isoprene permits the approximate evaluation of the chain transfer to monomer constant for anionic polymerization of isoprene and estimation of the parameter α in the relation [η] = K · [DPn]α.
Crystalline modifications of cellulose. Part IV. Determination of x‐ray intensity data
Authors: Mann J. , Roldan‐Gonzalez L. , Wellard H. J. 
Published: April 2003

AbstractThe intensities of x‐ray reflections from ordered regions of Cellulose I (ramie) an Cellulose II (Fortisan) have been determined by photometering the x‐ray diagrams. The results are reported as intensities of resolvable reflections, to provide a basis for comparison with postulated crystal structures to be described in Part V of this series. In many cases reflections from several crystallographic planes could not be resolved and the total intensity for the group of reflections is given. This procedure does not make full use of the experimental results; the factors which would have to be taken into account in a more complete interpretation of the data are discussed.
Crystalline modifications of cellulose. Part V. A crystallographic study of ordered molecular arrangements
Authors: Jones D. W. 
Published: April 2003

AbstractWith the arrangements of molecular chains postulated in Part III as a basis, crystal structures for the ordered regions of ramie and regenerated celluloses have been set up. Comparison of the (hkl) x‐ray intensities calculated for cellulose I structures with the measurements reported in Part IV reveals serious discrepancies on the first layer‐line. From extensive calculations over a range of structures, it appears that no conventionally ordered structure built from a P21 unit cell of approximate dimensions 8.2 × 10.3 × 7.9 A., β = 84°, can be expected to yield as weak (h1l) planes as are observed. An element of randomness in the polarity of the chains would diminish the discrete intensities on the higher layers relative to the (h0l) reflections and so be more in accord with experiment. For cellulose II, attention was concentrated on antiparallel chain structures with the r shift near 0.29. Although the overall agreement was better than for cellulose I, such structures did not account for the very weak low‐order (h1l) reflections observed. The disparity was not reduced by types of disordering acceptable on stereochemical and spectroscopic grounds. The major part of the disagreement is tentatively attributed to regarding the observed coherent scattering as emanating from fully ordered unit cells of the accepted dimensions and symmetry, and to neglecting contributions from oriented amorphous regions.
Absolute rate theory for spherulite growth of polymeric substances
Authors: Hirai Nishio 
Published: April 2003

AbstractThe rate of spherulite growth has been measured for various polymers. Several authors have developed the theory for the rate with emphasis on its temperature dependence but without reference to its absolute value. In this paper, a theory of the absolute rate of growth is put forward on the basis of the perfect crystal growth mechanism of Volmer‐Frenkel and the absolute reaction rate theory of Eyring. The linear rate of growth, G is given by

For typical polymers, this equation is approximated by

where d1 is the diameter of the polymer molecular, d3 the length of the segment, ηL the local viscosity near the crystal surface, ΔHm the heat of fusion for a mole of segments, Tm° the equilibrium melting temperatures, and ΔT = Tm° – T. The glass temperature for the local viscosity is assumed to be lower by δTg than that for usual viscosity, and the equilibrium melting temperature Tm° is assumed to be 5° higher than the apparent melting point Tm. The values of G calculated by this theory show good agreement with observed values for polyethylene succinate and nylon 6.
A study of the deuterium isotope effect in antioxidant activity
Authors: Shelton J. Reid , McDonel E. T. , Crano John C. 
Published: April 2003

AbstractIn an attempt to correlate the conflicting reports in the literature with regard to the presence of a deuterium isotope effect in antioxidant activity, this study was undertaken to investigate the factors on which this effect depends. It was found that variations in the magnitude and direction of the isotope effect in a study of this type could be brought about by varying each of the following factors separately: (1) concentration of the antioxidant; (2) temperature of the oxidation run; (3) nature of the antioxidant. The reason for the dependence of the isotope effect on these factors is thought to be the possibility for direct oxygen attack on the antioxidant, yielding radicals capable of beginning a kinetic chain. This study also demonstrated the amazing ease of exchange of the labile hydrogen on the antioxidant for deuterium in the presence of the inert organic solvent and heavy water. This is the basis for a very simple new procedure which was developed for the preparation of deuterated antioxidants. It also emphasizes that in an attempt to discover an isotope effect in antioxidant activity all water must be continuously excluded from the system. The isotope effects demonstrated in this and a previous study support the hydrogen abstraction mechanism for antioxidant activity.
The butyllithium‐initiated polymerization of 1,3‐butadiene
Authors: Kuntz Irving , Gerber Arthur 
Published: April 2003

AbstractThe structure of polybutadiene prepared by butyllithium initation in n‐heptane has been studied by four infrared procedures. A typical polymer prepared by n‐butyllithium at 30° gave values of 48–58% trans‐1,4‐ and 33–45% cis‐1,4‐, and 7–10% 1,2‐addition, depending on the particular analytical technique used. Iso‐ or n‐butyllithium gave polybutadienes with the same structure. Polymer stereochemistry is independent of monomer and initiator concentration and extent of polymerization conversion. Polybutadiene prepared in experiments from 4 to 80° showed the same structure. Polymerization in the presence of small amounts of ethers yields 1,2‐addition as the major structural unit. These results contrast with the reported behavior of isoprene in similar polymerizations where increasing alkyllithium concentration and reaction temperature increase the amount of 3,4‐addition and decrease the amount of cis‐1,4‐structure. Possible reaction routes for these transformations are discussed.
A theory of the thermodynamic behavior of nonelectrolyte solutions. III. The osmotic pressure of polymer solutions
Authors: Maron Samuel H. , Nakajima Nobuyuki 
Published: April 2003

AbstractData on the osmotic pressures of both dilute and concentrated polystyrene and polyisobutylene solutions in various solvents have been examined in terms of Maron's theory. It is shown that for each polymer‐solvent system at a given temperature the behavior over the entire concentration range studied can be characterized by a single interaction parameter μ, whose dependence on volume fraction v2 of polymer is given by

where μ° and σ° are constants. For two systems, where data are available, this linear relationship has been found to hold from v2 = 0 up to v2 = 0.90. With this relationship for μ, Maron's theory leads to functional plots for dilute solutions which are linear even in systems where the usual II/C vs. C plots are not straight lines. These plots yield the molecular weights from the intercepts and the quantities (μ° − σ°) from the slopes. However, the individual values of μ° and σ° cannot be obtained from dilute solution data. To arrive at these, data are required at concentrations higher than those customarily used for molecular weight determinations. The μ°'s show values which are frequently larger than 0.50 and which vary quite appreciably with change of solvent or temperature. Similarly the σ°'s are quite sensitive to these variables, and both positive and negative values have been observed for this quantity. On the other hand, the difference (μ° − σ°) is much less sensitive to these variables and consistently yields values of 0.50 or less. It is also shown that the parameter χ of the Flory‐Huggins theory does not measure explicitly the interactions in either dilute or concentrated solutions. Consequently, the dependence of χ on solution variables does not reflect directly the effect of such variables on the polymer‐solvent interactions in solution.
Transitions in ethylene polymers
Authors: Nielsen Lawrence E. 
Published: April 2003

AbstractA study of polyethylenes and ethylene–vinyl acetate copolymers by dynamic mechanical mesurements gives new information on the transitions in polyethylene polymers. The melting points agree with the predictions of Flory's theory. The alpha transition is shown to be due to the melting of crystallites containing ethylene sequences of lengths near the average sequence lengths; this transition is related to the lengths of crystallites. The beta transition is not necessarily due to branch points, as a number of noncrystallizable groups produce beta transitions at the same temperature. The beta transition degenerates into the gamma transition if the crystallinity is destroyed.
Polymerization of dichlorophosphinic nitrides
Authors: Konecny Jan O. , Douglas Catherine M. , Gray Marilee Y. 
Published: April 2003

AbstractPolymerization of the dichlorophosphinic nitride trimer, catalyzed by benzoic acid, ether, ethanol, or methanol, is first order in the trimer. With methanol and benzoic acid as catalysts, but not with ether, the first‐order rate constants increase linearly with catalyst concentration. Solution polymerization in benzene is somewhat slower than bulk polymerization.
A kinetic analysis for the free‐radical crosslinking of saturated polymers
Authors: Miller A. A. 
Published: April 2003

AbstractA general expression for the crosslinking efficiency in saturated polymers by added free‐radical initiators is derived on the basis of a steady‐state kinetic treatment of the following reactions: (a) dissociation of initiator to form R· radicals; (b) transfer to produce P· polymer radicals; and (c) the three recombination reactions of P· and R· radicals, only one of which (P· + P·) produces a polymer crosslink. The instantaneous crosslinking efficiency (crosslinks formed per molecule of initiator decomposed) is given by: C = (k[I]1/2 + 1)−2, where [I] is the instantaneous concentration of initiator and k is constant for a given polymer–initiator system at constant temperature. Depending on the value of k[I]1/2 compared to unity, C may vary from zero to unity. An average value C̄ of C and therefore the crosslink concentration for any degree of decomposition of the initiator is given by an integrated form of the above expression. These kinetic expressions are confirmed by experimental results on the crosslinking of a polydimethylsiloxane polymer by benzoyl peroxide at 125°C. (previously reported work) and by dicumyl peroxide at 170°C. (present work). Both experiment and theory suggest that with polymers such as dimethylsiloxanes, which are more resistant to free‐radical attack, ionizing radiation may have unique advantages over conventional chemical initiators for the production of polymer radicals for crosslinking or graft polymerization.
Ultrasonic degradation of polymer molecules in solution: Some comments on recent papers
Authors: Ovenall Derick W. 
Published: April 2003

AbstractRecent papers on the ultrasonic degradation of polymer molecules in solution are discussed. It is pointed out that the use of the Staudinger equation to derive weight‐average degrees of polymerization from the viscosities of benzene solutions of polystyrenes is a source of error, since these solutions have been found to obey the Houwink equation. Some measurements of degradation rates by the use of diphenyl picryl hydrazyl as a free radical scavenger are considered, and it is concluded that they can be fitted almost equally well by two different rate equations.
Tracer techniques for the determination of monomer reactivity ratios. I. A direct counting technique applied to the styrene–methacrylate copolymerization
Authors: Wiley Richard H. , Sale Edwin E. 
Published: April 2003

AbstractA direct counting technique has been evaluated and used for the determination of monomer reactivity ratios. Windowless gas‐flow counting of polymer samples plated directly on planchets gave reproducible counting rates and nearly linear self‐absorption curves in the 8–25 mg./planchet range. Copolymer composition data obtained by radioactivity assay on a series of styrene C14/methyl methacrylate copolymers gave monomer reactivity ratios of r1 = 0.48, r2 = 0.46 at 60° and r1 = 0.60, r2 = 0.55 at 132°; these values are in good agreement with previously recorded values.
Tracer techniques for the determination of monomer reactivity ratios. II. Monomer reactivity ratios in copolymerizations with divinyl monomers
Authors: Wiley Richard H. , Sale Edwin E. 
Published: April 2003

AbstractMonomer reactivity ratios have been determined for styrene (r1 = 0.35)–ethyleneglycol dimethacrylate (r2 = 0.65) and styrene (r1 = 0.65)‐m‐divinylbenzene (r2 = 0.60), a tracer technique being used to determine the copolymer composition. The data for these divinyl monomers give intersect plots with three different monomer ratios which determine the reactivity ratios. The usual two‐component copolymerization equation is modified by the use of 2M2 for the M2 term where M2 is the mole percent of the divinyl monomer in the charge. Similar data for p‐divinylbenzene do not locate a unique set of reactivity ratios. It is concluded that the copolymerization behavior of symmetrical divinyl monomers in which the vinyl groups do not interact can be evaluated through use of the two‐component copolymerization equation.