bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymer–diluent interactions. III. Polyethylene—diluent interactions
Authors: Coran A. Y. , Anagnostopoulos C. E. 
Published: April 2003

AbstractThe interactions between polyethylene and a number of hydrocarbon diluents were characterized on the basis of the Flory‐Huggins interaction parameter χ and the closely related heat of mixing parameter B. The evaluations of these parameters were based on Flory's statistical‐thermodynamic treatment of the effect of diluents on the melting points of crystalline polymers. Necessary for each evaluation was a single microscopic determination of the depressed melting point of polyethylene in its mixture with a given diluent as indicated by the disappearance of the last visible traces of crystallinity upon slow heating. Each mixture was diluted to an extent that the volume fraction of diluent approximated unity. This permitted the use of a simplified form of the Flory equation. The data obtained from the study of thirty diluents were utilized in an attempt to correlate diluent structure with solvency. Generally, the various types of hydrocarbon diluents can be rated in the following order of increasing solvency: aromatic, alkylaromatic, aliphatic, alicyclic. In addition, it was demonstrated that the value of B for a given diluent can be reliably estimated as a function of a new parameter which is calculated from the diluent structure, density, and an estimated value of the ionization energy. This new parameter also correlates well with the solubility parameter δT.
The use of high pressure to study polymer—solvent interaction
Authors: Ham Joe S. , Bolen Max C. , Hughes James K. 
Published: April 2003

AbstractThe behavior of polymer—solvent systems has been studied as a function of hydrostatic pressure to 3000 atm. The swelling of crosslinked neoprene and crosslinked Hevea has been studied in several solvents, and the temperature of phase separation of polystyrene in cyclohexane has been determined. These measurements permit an indirect evaluation of the volume of mixing that is felt to have advantages over the direct method due to the small magnitude of the effect in polymer systems. In all of the cases studied by the swelling technique, the volume of mixing is negative and tends to be greater in magnitude the better the solvent. For the very poor solvent—polymer system studied by the precipitation technique, a small positive value is obtained. In addition, the compressibility of swollen polymers is compared with that expected from an assumption of additivity and found to be much smaller. These phenomena are presumably the result of a more tightly packed liquid structure within the polymer network. This explanation suggests that the descriptions of the volume of mixing in terms of the apparent specific volume, while certainly formally correct, may be misleading physically. An attempt to relate the observations on these systems to a theory involving a power series expansion in terms of the solvent fugacity was unsuccessful due to the slow convergence of the series.
Light scattering by poly‐L‐xbenzyl glutamate solutions subjected to an electrical field
Authors: Wallach Morton L. , Benoit Henri 
Published: April 2003

AbstractA study has been made of the light scattering of poly‐L‐benzyl glutamate solutions subjected to orientation by an electrical field. Measurements were taken of the effect as a function of the field strength, the angle of observation, the direction of the field, and the frequency of the field. The principal results obtained were the following. (a) The helical molecules are not deformed by the electrical field. (b) The molecular orientation is due primarily to a permanent electric moment whose axial component per monomer unit is of the order of 3 Debye. (c) As predicted by the theory of Burgers, the rotatory diffusion constant was found to vary inversely as the cube of the rod length.
Molecular motion in polystyrene and some substituted polystyrenes
Authors: Odajima A. , Sauer J. A. , Woodward A. E. 
Published: April 2003

AbstractProton magnetic resonance spectra of nine substituted polystyrenes: polymers of o‐methyl, m‐methyl, p‐methyl, p‐chloro‐, 2,4‐dimethyl‐, α,β,β′‐trideutero‐, β‐ deutero‐, 2,6‐dimethyl‐4‐tert‐butyl‐, and p‐tert‐butylstyrene, in addition to five polystyrene samples differing in molecular weight (M̄n's from 1.25 × 105 to ∼35 × 105) or tacticity have been obtained at temperatures from 77 to above 400°Kg. Measurements have also been made on p‐tert‐butyltoluene, 2,4‐dimethylstyrene, and 2,6‐dimethyl‐4‐tert‐butylstyrene. All polymers studied were found to exhibit single‐component derivative line shapes and to undergo rapid motional narrowing with increasing temperature in the region of the glass transition; in this region the line width for atactic polystyrene was found to be essentially independent of molecular weight. At lower temperatures a gradual line narrowing effect was also observed for some of the polymers, even near 77°K., and is attributed to limited phenyl or substituted phenyl group oscillation. This effect was apparent for polystyrene, poly‐α,β,β′‐trideutero‐, poly‐β‐deutero‐ poly‐p‐chloro, and poly‐p‐methylstyrene, less apparent for the o‐ and m‐methyl compounds and the p‐tert‐butyl‐substituted polymer, and absent for the 2,4‐dimethyl and the 2,6‐dimethyl‐4‐tert‐butyl polymers. By a comparison of experimental second moments with approximate ones obtained from theory, it is concluded that rotation of all methyl groups attached directly to benzene ring for all polymers studied is taking place at 77°K. For both p‐tert‐butylsubstituted polymers and the low molecular weight analogs, a motional narrowing process occurs in the ≤77° to 150°K. region, and for all but 2,6‐dimethyl‐4‐tert‐butylstyrene this is attributed to rotation of the methyl groups in the tert‐butyl part of the molecule; for the latter compound, onset of rotation of one of the methyl groups attached directly to the ring in addition to the methyl in the tert‐butyl part is responsible for the line narrowing. The contributions of various proton interactions to the total second moment of polystyrene and its derivatives are discussed.
Synthesis of new monomers and polymers. III. Preparation of poly‐N‐salicylidenevinylamine and derivatives
Authors: Decoene C. , Teyssié Ph. 
Published: April 2003

AbstractBy condensation of polyvinylamine with several aromatic aldehydes, poly‐Schiff bases were obtained, which were practically 100% pure. The polysalicylidenevinylamine and its 5‐chloro‐, 5‐nitro, 4‐hydroxy, and 3‐methoxy derivatives, as well as the poly‐2‐hydroxynaphthylidenevinylamine and the polyfurfurylidenevinylamine were isolated. Their structure was checked by elementary analyses as well as by qualitative and quantitative infrared spectrophotometry. These compounds from interesting polychelates with transition metals.
Diffusion, thermodiffusion, and thermal diffusion of polystyrene in solution
Authors: Meyerhoff G. , Nachtigall K. 
Published: April 2003

AbstractDiffusion coefficients D and Ludwig‐Soret coefficients D′/D of polystyrene in toluene were determined in a convection‐free thermodiffusion cell of 1 to 4 mm. height, 100 mm. length, and at a temperature differences of 0.1 to 0.3°C. The cell had two chambers, thus allowing observation of the concentration gradient alone by optical elimination of the temperature gradient. Philpot‐Svensson and Gouy optical methods were used. Both equilibration from homogeneous concentration to Ludwig‐Soret equilibrium and from this back to homogeneous concentration lead to D and D′/D. The last method, operating with ΔT = 0 gave more exact results. It was possible to measure very low diffusion coefficients (below 10−7 cm.2sec.−1). For sharp fractions the agreement with the free diffusion is good. For broader samples the thermodiffusional D is smaller than D of free diffusion. This difference is in accordance with the different averaging of the two methods. Up to ΔT = 0.3°C. no variation of D′/D with temperature was found. The Ludwig‐Soret coefficients increase with increasing molecular weight M and decreasing concentration. The thermal diffusion coefficient D′ is nearly independent of M and shows only a very slight decline with concentration. The results of our experiments are discussed together with the work of other authors using different techniques.
Determination of the dependence of the ultracentrifugal sedimentation coefficient on concentration by a single experiment
Authors: Gehatia Matatiahu 
Published: April 2003

AbstractThe dependence of the ultracentrifugal sedimentation coefficient s on the concentration has been derived directly from the theory of hydrodynamics for the case of very dilute solutions. The following general expression has been obtained: s = s0(1 − k1c1/3 − k2c), where s0 is the zero value of s and k1 and k2 are constants. If compact and not extremely big molecules are investigated under the usual experimental conditions k1c1/3 ≪ k2c. In such a case the term k1c1/3 can be neglected, and the general expression leads to the well‐known equation: s = s0(1 − k2c). As s depends linearly on c, the constant s0 can be estimated with help of the straight line obtained if s is plotted against c. For very big and elongated particles, however, measured at very high dilutions k1c1/3 ≫ k2c. In this case the approximate equation s = s0(1 − k1c1/3) holds, and for the purposes of extrapolation s must be plotted against c1/3. A method has been developed which enables to decide from one experiment which of the two given equations may be preferred, or if s can be seen as a constant.
Crosslinking of single linear macromolecules
Authors: Kuhn Werner , Balmer G. 
Published: April 2003

AbstractWhen a crosslinking agent is added to a very dilute solution of a linear high polymer, there will be practically exclusively a self linking of the individual statistical coils, i.e., the molecules of the crosslinking agent will link different parts of the same macromolecule, transforming the original linear high polymer into a three‐dimensional network, practically without a change of its molecular weight. The process of self‐linking of a single coil is associated with a contraction of its average external dimensions and therefore with a decrease of the intrinsic viscosity. If the crosslinking produced by the action of v molecules of the crosslinking agent on one linear polymer molecules occurs statistically and if the original linear high polymer molecule is made of Nm statistical chain elements, a decrease of the intrinsic viscosity should occur from the value [η]open to [η]v crosslinks, statist, where \documentclass{article}\pagestyle{empty}\begin{document}$ [\eta ]_{\nu {\rm crosslinks, statist}} = [\eta ]_{{\rm open}} [1 - \nu (\sqrt 2 /\sqrt {N_m } )] $\end{document}. In order to test the validity of this formula a dilute, slightly acid solution of polyvinyl alcohol with M = 100,000 was crosslinked by means of terephthalaldehyde [CHOC6H4CHO]. The agreement of the values of [η] observed in very dilute solution with the theoretical value indicates the actual statistical formation of cycles through the reaction of terephthalaldehyde on dissolved solitary linear polyvinyl alcohol molecules.
Polymer solutions. VIII. A new absolute method of molecular weight determination of polymers from solution viscosities
Authors: Gundiah S. , Kapur S. L. 
Published: April 2003

AbstractAn empirical method for absolute molecular weight determination of polymers from viscosity measurements is described. The essential assumptions of the method are: (a) the Huggins' slope constant for any flexible polymer has a maximum value of 0.5 at the precipitation point; (b) the viscosity—concentration plots for a particular polymer in different solvents (when extrapolated) meet at a common point; (c) the ordinate at the common point of intersection [η]R (when the viscosity function is In ηr/c is identical with the limiting viscosity number for the polymer at the point of incipient precipitation); (d) the value of the ordinate at the common point of intersection [η]R is related to molecular weight by the relation [η]R = 9.0 × 10−4M0.5. The method gives satisfactory results in case of polymers like polystyrene and polymethyl acrylate.
Studies on the configuration and conformation of vinyl‐type polymers. II. Temperature dependence of the infrared spectrum of polyvinyl chloride in solution and stereoregularity
Authors: Takeda Masatami , Iimura Kazuyoshi 
Published: April 2003

AbstractThe temperature dependence of the infrared spectra of polyvinyl chlorides in concentrated cyclohexanone solution has been studied. It is found that the absorbance ratio of the band at 696 cm.−1 to the band at 616 cm.−1, D696/D616, decreased as the measuring temperature was raised. This experimental finding has been interpreted as due to the reversible conformational change of the chain in the syndiotactic sequences of PVC. The syndiotacticity α of PVC was estimated to be in the range of 0.86 to 0.52 with varying of the polymerization temperature from −60°C. to 50°C. The stable conformations of the polymer chain in solution were also discussed.
Molecular weight of polymers from electrical resistivity of solutions
Authors: Purdon J. R. , Morton M. 
Published: April 2003

AbstractAn investigation has been carried out to further establish the usefulness of electrical resistivity techniques for the study of polymerization kinetics, and to determine the extent of molecular weight dependence of electrical resistivity. The resistivity increment, (p − p0)/p0, which may be regarded as the fractional increase in resistivity of a system due to the presence of polymer, was found to be directly proportional to the concentration of polymer in solution. Based on the assumption that conductance in polymeric systems occurs by migration of ionic impurities, the resistivity increment was shown to be identical to the specific local viscosity. A marked dependence of (p − p0)/p0 upon molecular weight was found. The relationships observed provide expressions for determination of molecular weight from resistivity data in the systems: polystyrene‐styrene, polystyrene‐cyclohexane, and poly(methyl methacrylate)‐benzene. Furthermore, these relationships indicate the existence of a “critical packing volume” for the polymer chains in solution. This effect permits a determination of the unperturbed end‐to‐end chain dimension of the polymer (polystyrene) which agrees reasonably well with the published value.
Branching in isoprene polymers of regular structure
Authors: Poddubnyi I. Ya. , Ehrenburg E. G. 
Published: April 2003

AbstractBranching in isoprene polymers with cis‐1,4 content of ∼85% obtained by polymerization in the presence of a complex catalyst and under the action of lithium was determined by studying intrinsic viscosity of polymer fractions in an ideal solvent. It was established that macromolecules of polyisoprenes obtained with a complex catalyst under polymerization conditions commonly used are essentially linear. At the same time, in the polymers studied, there is a fraction (∼10% of the polymer weight) consisting of colloidal size particles formed by highly crosslinked polymer molecules. A rubber sample of the above type prepared with uncontrolled dosage of catalyst components and at elevated temperature proved to be a highly branched polymer. The discovered features in hydrodynamic behavior of macromolecules in benzene solutions suggest that trans units in the macromolecules of polyisoprenes obtained in the presence of the complex catalyst are not randomly distributed along the chain but form comparatively long blocks. The intrinsic viscosity—molecular weight relation in benzene solutions was determined for both types of polymers studied.
Permanganate—oxalic acid as a redox initiator in aqueous media. Part I. The initiating radical and general features
Authors: Palit Santi R. , Konar Ranjit S. 
Published: April 2003

AbstractPolymerization of aqueous methyl methacrylate solution by oxalic acid (4.0 × 10−2 to 0.0625 × 10−2 mole/l.) and permanganate (0.633 × 10−5 to 63.3 × 10−5 mole/l.) system as redox initiator has been studied. Oxalic acid by itself can not initiate polymerization in the dark but does so strongly even in diffuse light or weak illumination. Permanganate can initiate polymerization provided the solution is sufficiently acidic to dissolve the separated colloidal MnO2 which tends to inhibit polymerization. The MnO4−‐oxalic acid system is a powerful redox initiator provided the acid strength (either of added H2SO4 or of oxalic acid itself) is sufficient to dissolve MnO2. The polymer always separates as a coarse coagulum (suspension). The polymers have been examined for endgroups by the dye test as developed in this laboratory. Oxalic acid‐initiated (in sunlight) as also oxalic acid—ferrous ion‐initiated and KMnO4—H2C2O4‐initiated polymers contain carboxyl endgroups. MnO2—H2SO4 acid‐initiated polymers, have been found to contain sulfate endgroups. On increasing the ratio of oxalic acid to permanganate, the carboxyl endgroups tend to decrease, and ultimately very faint test for carboxyl is obtained. This is in agreement with the suggestion made by previous workers that under such conditions carboxyl radical‐producing reactions are suppressed.
Methods of predicting radiation‐induced changes in the mechanical properties of high polymers
Authors: Fritz E. G. 
Published: April 2003

AbstractA discussion is presented of the various problems associated with the formulation of predictive techniques relating to the mechanical response of high polymers to radiation. In particular, dosimetric difficulties and errors arising from disregard of sample variations are analyzed. Criteria for the engineering evaluation of radiation sensitivity are examined. The usefulness of rank correlation in preliminary analysis of radiation effects data is outlined. Typical examples are given of explicit correlations between properties, the application of statistical kinetic theory, and semiempirical and empirical response relationships. The limitations of the various approaches are discussed.
Polymerization in the crystalline state. II. Alkali acrylates and methacrylates
Authors: Morawetz H. , Rubin I. D. 
Published: April 2003

AbstractAlkali acrylates and methacrylates were irradiated with gamma rays from a Co60 source at −78°C. and their subsequent polymerization was studied in vacuo in the temperature range 0 to 155°C. Potassium acrylate proved to be the most rapidly polymerizing solid monomer studied to date; it reacted at 0°C. faster than the lithium salt at 101°C. or the sodium salt at 120°C. The reaction rate of the acrylates decayed rapidly at low polymer yields which were, for long polymerization times, linear in the logarithm of time. The activation energy for the polymerization of potassium acrylate was 16.7 kcal./mole. The chain length of the polymer was independent of the polymer yields in all kinetic runs except one and was an order of magnitude higher for potassium acrylate than for the sodium or the lithium salt. Sodium methacrylate was more reactive than potassium methacrylate; the lithium salt of methacrylic acid was entirely inert. The sodium methacrylate polymerization had an initial accelerating phase. Studies of x‐ray diffraction of the polymerizing potassium acrylate showed only minor changes in the diffraction pattern of the monomer, the size of the unit cell remaining almost unchanged. Poly(potassium acrylate) produced in the solid state showed four diffuse diffraction rings which were not observed in samples prepared from poly(acrylic acid) obtained by polymerizing a benzene solution of the monomer. While the x‐ray data indicated the existence of a separate polymer phase in the polymerizing salts, the pronounced difference in the characteristics of the polymerization process of different salts of the same monomeric anion pointed to a control of the reaction by the geometry of the crystal lattice. The evidence suggests that the polymer lies in an amorphous phase but that the reactive ends of growing chains are anchored in the monomer lattice. Electron spin resonance spectra are similar for irradiated potassium acrylate and sodium methacrylate, but the potassium acrylate spectrum changes gradually from a three‐peak to a single‐peak structure when the sample is heated to 100°C., while the other two salts have spectra which are not affected by a similar heating cycle. The absence of the characteristic ESR spectrum of polymethacrylate radicals in irradiated sodium methacrylate suggests that under the experimental conditions used few of the primary radicals were able to initiate chains. A five‐peak ESR spectrum was observed in irradiated sodium acrylate.
Polymerization in the crystalline state. III. Methacrylic acid and butadiene‐1‐carboxylic acid
Authors: Morawetz H. , Rubin I. D. 
Published: April 2003

AbstractMethacrylic acid polymerized in the solid state leads to a much less syndiotactic polymer than when polymerized in the liquid state. This is taken as additional evidence for the importance of the geometry of the monomer crystal lattice in solid state polymerization. Butadiene‐1‐carboxylic acid polymerizes spontaneously in the solid state to a cross‐linked product, while the sodium, potassium, and barium salts of this acid are stable and polymerize very little, even on gamma‐ray irradiation.
Kinetics of thermal decomposition of dimethyl‐N‐(2‐cyano‐2‐propyl)ketenimine by nuclear magnetic resonance spectroscopy
Authors: Smith P. , Muller N. , Tosch W. C. 
Published: April 2003

AbstractThe kinetics of the thermal decomposition of dimethyl‐N‐(2‐cyano‐2‐propyl)ketenimine, DKI, in benzene solution over the 61–92°C. range have been investigated by means of proton magnetic resonance spectroscopy for quantitative analysis of reaction mixtures. The NMR equipment used comprised a Varian Model 3311 spectrometer, operating at a fixed radio frequency of 56.445 Mcycles/sec. and equipped with the Model V‐K 3506 super‐high‐resolution field‐stabilizing unit and the Model V‐K 3507 slow‐sweep unit. The kinetic data obtained tally closely with those reported earlier for a nitrometric and ultraviolet spectrophotometric study of the thermal breakdown of 2,2'‐azobisisobutyronitrile, AZO, in the same solvent within the 60–80°C. range. Consequently the general mechanism assumed in interpreting the previous results for the AZO decomposition is confirmed. They also agree with all other comparable data available as well as expected. As a natural part of this study, it has been shown that NMR provides reliable and convenient methods of quantitative analysis of reaction mixtures when DKI or AZO is thermally decomposed. One variation of the analytical technique practiced involved comparison of the C13‐sidebands in the NMR spectrum of a major constituent of a mixture with the main spectrum from a minor constituent. This was especially valuable for settling the initial purity of the DKI decomposed and the extent to which side products such as isobutyronitrile, methacrylonitrile, and 2,3,5‐trimethyl‐2,3,5‐tricyanohexane were formed.