bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of molecular motions on radiation‐induced reactions in polymers
Authors: Wündrich Konrad
Published: April 2003

There have been several investigations dealing with the influence of the glass transition on the rate of radiation‐induced reactions, especially the crosslinking reaction. On the other hand, no correlation has been reported between secondary transitions and the variation of a reaction rate. In the present work, the degradation of poly(methyl methacrylate) in the temperature range of −196 to 160°C has been studied. Two breaks in the Arrhenius plot were found. The first one is located at −5°C and can be correlated with the γ transition, which has been assigned to the hindered rotation of the ester group whose scission initiates the degradation. It is concluded that the thermal excitation of the bond rotation can either increase the scission rate or decrease the recombination rate of reactive intermediates by expanding the cage of the surrounding molecules. If the second mechanism occurs, the rotation of the α‐methyl group should also be expected to favor the degradation. However, a second break in the Arrhenius plot was found at −130°C, and therefore significantly above the δ transition. The influence of this motion is therefore not clear. Certain radiation‐induced reactions of poly(vinyl chloride), known from literature, seem to be influenced by a secondary transition. It is concluded that secondary transitions may be significant for scission reactions. This suggests, with respect to the known significance of the glass transition, that the various types of molecular motions in polymers may influence radiation‐induced reactions.
Dynamic light‐scattering study of an ethylene–methacrylic acid copolymer and its salt
Authors: Prud'homme Robert E. , Stein Richard S.
Published: April 2003

Dynamic light‐scattering experiments were performed on an ethylene–methacrylic acid copolymer and its sodium salt. The in‐phase ΔI′ and out‐of‐phase ΔI″ components of the light scattering were measured in a temperature range between 25 and 65°C for both samples. No transition is seen in this temperature interval for the acid, but a clear transition occurs around 40°C for the salt. This transition is associated with the softening point of the ionic domains present in the sample.
Light scattering from assemblies of spherulites
Authors: Prud'homme Robert E. , Stein Richard S.
Published: April 2003

A general equation describing the small‐angle Hv light‐scattering intensity for a system of N undeformed spherulites located at random within the sample and taking into account the truncation and interference effects is given. Scattering contour plots or radial scans are reported for various arrangements of the N spherulites. The results show that the interference effect may explain the speckled appearance of the experimental patterns. Moreover, the interference and truncation effects (for the special cases where truncation is considered here) do not seem to shift the position of the maximum scattering angle of the cloverleaf pattern as calculated from the single spherulite theory. Finally, the calculations show that the truncation effect increases the relative intensity of the pattern at large and low scattering angles and at azimuthal angles 0 and 90°C, as compared with the intensity at the position of maximum scattering angle.
Random grafting statistics in graft distribution analysis
Authors: Tung L. H. , Wiley R. M.
Published: April 2003

Graft distribution functions have been derived from random grafting statistics. Among the functions, the weight fraction of ungrafted backbone chains, the molecular weight distribution of the ungrafted backbone chains and the GPC apparent molecular weight distribution of the graft copolymer have been found to agree with experimental values determined for a graft copolymer system in which grafting was expected to be random. The other functions, which are not directly measurable, are therefore probably also correct. In analytical work the entire set of graft distribution functions may be computed for a graft copolymer system from the following experimental data: (1) molecular weight distribution of the starting backbone chains; (2) the chemical composition of the mixture of the graft copolymer and ungrafted backbone; (3) the graft side‐chain molecular weight distribution, which may be assumed to be identical to that of the ungrafted homopolymer separable from the reaction mixture.
Experimental evidence for a low‐lying torsional mode in polymers
Authors: Madding R. P. , Fehl D. L. , Dillinger J. R.
Published: April 2003

Longitudinal and transverse sound velocities have been measured in several samples of polystyrene crosslinked with various weight percentages of divinylbenzene. Specific heats of these same samples have been measured previously. These data obtained calorimetrically, together with similar data obtained by others for some other polymers, can be accounted for by postulating the existence of a fourth mode of vibration with a velocity close to that measured for the two transverse modes. It is suggested that this fourth mode is one arising from the torsional coupling of the side groups along the backbone chain of the polymer molecule.
Dielectric relaxations and molecular motions in poly(vinylidene fluoride) with crystal form II
Authors: Nakagawa Koichi , Ishida Yoichi
Published: April 2003

Molecular motions in poly(vinylidene fluoride) were studied by dielectric measurements. Of the three relaxation processes, the αa and the αc were studied. The αa relaxation was attributed to the molecular motions in the amorphous regions and the αc relaxation to molecular motions in the crystalline regions and their surfaces. The relaxation time and the magnitude of the αa absorption were analyzed on the basis of the Adam‐Gibbs theory of the temperature dependence of the size of the cooperatively rearranging region. As a result it was concluded that the molecular structure of crystal form II holds locally, even in the amorphous regions. The relaxation time and the magnitude for the αc absorption were analysed on the basis of the two‐site model. It was concluded that the αc relaxation is attributable not only to molecular motions in the folds of the lamellar crystals, but also to those in the interior of the crystal; the folded chain is relatively mobile, while the molecular chain in the interior of the crystal executes restricted rotation around the chain axis.
Mass and momentum transfer in polymers. II. Effects of concurrent sorption or desorption of penetrant on tensile creep of an amorphous polymer
Authors: Machin D. , Rogers C. E.
Published: April 2003

Techniques have been developed for the prediction of tensile creep behavior of rubbery amorphous polymers with concurrent sorption or desorption of penetrant. The procedures require knowledge of polymer–penetrant interdiffusion behavior and the creep behavior of dry polymer and of polymer swollen to equilibrium. The techniques are based upon a moving boundary treatment, proposed by Kishimoto and Fujita, which has been modified and extended to consider two types of boundary definition, desorption in addition to sorption, and extension of the analysis to longer times. Calculated curves for the concurrent processes of diffusion and creep in the systems poly(n‐butyl methacrylate) with ethanol, methyl ethyl ketone, or benzene vapors at 23°C agree to a good approximation with those measured directly. Diffusion coefficients calculated from the measured concurrent curves also are comparable with those measured directly in previous studies. The techniques are useful initial procedures which, with some further modification or extension, should lead to a more general description of concurrent mass and momentum transfer in polymer–penetrant systems.
Mass and momentum transfer in polymers. III. Effects of liquid penetrants on tensile stress relaxation of amorphous polymers
Authors: Machin D. , Rogers C. E.
Published: April 2003

Sorption, diffusion, swelling, and tensile stress relaxation measurements were made at room temperature (23°C) for the systems poly(n‐butyl methacrylate) (PBMA) with liquid methanol and ethanol, and poly(methyl acrylate) (PMA) with liquid water. Stress relaxation curves for the fully swollen polymers could be superimposed approximately with those for the dry polymers by appropriate shifting along the long axes. For PMA–water the measured curve for stress relaxation with concurrent sorption could be predicted accurately by using a moving boundary theory with data measurements of stress relaxation of the unswollen and swollen polymer combined with sorption data. The modified moving boundary theory is generalized to include the effects of dimension changes through swelling and the larger effects of plasticization associated with sorption of liquids. This improved theory accurately predicts measured curves of stress relaxation with concurrent sorption for the PBMA–alcohol systems from individual stress relaxation, sorption, diffusion and swelling data. The general approach should be applicable to other amorphous polymer–liquid swelling agent systems. The anisotropic nature of swelling of polymer films and its effect on calculated diffusion coefficients are discussed briefly.
Molecular weight distribution and molecular structure of polyethylene produced by radiation‐induced polymerization
Authors: Yamaguchi Kouichi , Wada Takeshi , Maruyama Shinsaku , Takehisa Masaaki
Published: April 2003

The molecular weight distribution of polyethylene produced by radiation was calculated according to a kinetic scheme. The calculated molecular weight distribution was compared with the results deduced from gel‐permeation chromatography. The observed distribution curve from GPC was broader and showed a lower degree of polymerization than the calculated one. Discrepancies between observed and calculated curves can be explained if the polymer contains nonsteady‐state products and if the reaction mechanism includes chain transfer to dead polymer. By this reaction long‐chain branching would occur. Several long‐chain branches per polymer molecule were indeed found, as inferred from solution properties.
Crystal structure of polychlorotrifluoroethylene
Authors: Mencik Zdenek
Published: April 2003

The crystal structure of polychlorotrifluoroethylene has been studied. The pseudohexagonal lattice parameters are a = 6.438, c = 41.5 Å. The polymer chain is found to be helical with on the average 16.8 monomer units in one turn of the helix (equal to c). The skeletal angles on the CF2 and CFCI atoms are found to differ by 5 to 7 degrees. The polymer chain is found to accommodate these alternating angles by twisting around the axis of the helix. The result of the x‐ray diffraction study agrees best with the assumption that the polymer is atactic with random position of the chlorine substituent. This randomness affects the microstructure of the polymer chain to such an extent that the diffraction effects are those of a system of continuous helices.
Scattering from truncated spherulites
Authors: Prud'Homme Robert E. , Stein Richard S.
Published: April 2003

A general two‐dimensional theory is derived to explain the light scattering from truncated spherulites. The severity of the truncation is expressed by a statistical parameter σ2/ā2 which is the ratio of the variance σ2 of the size of the spherulite to the square of its average size ā. The Hv light‐scattering patterns are calculated for different values of the truncation parameter. It is observed that the truncation decreases the position of maximum scattering intensity of the pattern. It also increases the scattering intensity at small and large angles, but reduces it at intermediate angles. For a spherulitic polyethylene sample, the truncation parameter is found to equal 0.100 ± 0.030 as measured microscopically. The theory can also be used to calculate light‐scattering patterns from row‐nucleated spherulites. If it is assumed that the interference effect averages out to zero when a large number of spherulites is involved, a single “sliced” spherulite model can be used. Then, the scattering intensity per unit area decreases as the “slice” becomes very thin.
Thermoelasticity of stretched elastomers under small torsions: Effects of crosslinking, extension, and swelling
Authors: Gent A. N. , Kuan T. H.
Published: April 2003

By using a simple version of Treloar's torsion method the internal energy contribution Me to the restoring couple M has been determined for stretched testpieces subjected to small torsions. Values obtained for Me/M decreased significantly with increasing extension. Corresponding decreases were observed on swelling, but no specific effect of swelling liquids could be detected. The degree of crosslinking had no effect on Me/M. Thus, Me/M at small strains appears to reflect a characteristic molecular property, largely independent of local environment, network density, or type of deformation, as Flory has maintained. The present values are generally consistent with previously published data, except in the case of polyethylene, for which a much larger negative value is obtained, i.e., −1.6 compared to −0.5. The reason for this discrepancy is not known.
Polymerization during crystallization of selenium
Authors: Coughlin Michael C. , Wunderlich Bernhard
Published: April 2003

The crystallization of selenium from the melt has been studied as a function of time at 90, 126, and 200°C by following the density and the concentration of Se8 rings. The crystallization is shown to involve crystallization of the polymeric species in the melt and, especially at later stages of the crystallization, crystallization during polymerization. A kinetic scheme has been developed which permits the description of the experimental data.
Relative rates of creep and relaxation in shear, elongation, and isotropic compression
Authors: Markovitz Hershel
Published: April 2003

The relative rates of relaxation and creep in shear, elongation, and isotropic compression are discussed in terms of the theory of linear viscoelasticity. Exact expressions are given for the creep rates; for the relaxation rates approximations are found which are useful in the glassy range where the amount of relaxation is small. Among the results of interest is the relation:

valid if d In B/d In t is less than d In J/d In t as is intuitively expected and experimentally found. Here J(t), E(t), and B(t) are the shear, tensile, and bulk creep compliances, respectively. For polymers in the rubbery and flow regions, (d In J/d In t)/(d In D/d In t) is very close to 1(usually within 0.01%); in the glassy region, it is unlikely to be greater than 1.2.
Generalized characterization of relaxation properties and high elasticity of polymeric systems
Authors: Isayev A. I.
Published: April 2003

Measurements of apparent viscosity, normal stress coefficient, and storage and loss moduli have been used to determine the characteristic relaxation time. The ratio of the characteristic relaxation time θin corresponding to a given deformation rate ˙γ to that of the initial state θe is found to be a function of ˙γθin. For a wide range of polymeric systems, the ratio of normal stress to the initial high elasticity modulus and to the high elastic deformation γe are the same function of ˙γθin. It has been established that γe, like other viscoelastic characteristics of polymer systems, is determined by the relaxation properties and their variation due to deformation. The dependence of γe on θe/θin is common to a wide range of polymeric systems. The generalized characteristics were independent of the nature of the polymeric chain, molecular weight, molecular weight distribution, temperature, polymer concentration in solution, and solvent type. These results allow us to describe approximately normal stresses and high‐elastic deformations as functions of shear rate and storage and loss moduli as functions of frequency, if we know θin the relation between shearing stress and shear rate.
Determination of atomic stress distribution in stressed polymers by infrared spectroscopy
Authors: Vettegren V. I. , Novak I. I.
Published: April 2003

An attempt was made to evaluate stresses on chemical bonds in axially stressed polymers from the shift of skeletal vibration frequencies in chain molecules. The maximum stress on chemical bonds was found to be at least ten times the average stress on the specimen.
The nature of dielectric losses in H‐Film
Authors: Wrasidlo W. J.
Published: April 2003

Based upon the high‐temperature solid‐state dielectric behavior of H‐Film and supporting evidence from infrared spectroscopy, heat capacity, thermal expansion, and dynamic mechanical measurements, it is concluded that the actual chemical structure of H‐Film is far more complex than previously expected. The very unusual thermal properties of this polymer, such as lack of a glass transition temperature, its extreme insolubility, and high dielectric losses above 250°C with only weakly corresponding mechanical losses, suggest that in addition to the pyromellitimide repeat unit, a significant part of the structure consists of amide groups, probably in the form of crosslinks.
Carbon‐13 spin‐lattice relaxation study of linear polymers in solution
Authors: Inoue Yoshio , Nishioka Atsuo , Chûjô Riichirô
Published: April 2003

Proton‐decoupled, partially relaxed, Fourier‐transform NMR of 13C in natural abundance was used to determine spin‐lattice relaxation times of individual carbons of polyisobutylene, polyacrylonitrile, poly(vinyl chloride), and poly(vinyl alcohol) in solution. It is shown that the relaxation times are independent of the difference in stereochemical configuration. From the values of the nuclear Overhauser enhancement factor it is shown that the relaxation times are independent of the difference in stereochemical configuration. From the values of the nuclear Overhauser enhancement factor it is shown that the excess spin energy from equilibration of all the 13C, even of quaternary carbons, in the polymers dealt with here is transferred to the lattice mainly through 13C‐1H dipolar interactions. It is shown that the segmental motions responsible for the spin‐lattice relaxation of the polymer skeleton in solution can be described by the isotropic model within a good approximation, except for poly(vinyl alcohol) at low temperature. The activation energies of skeletal and internal methyl motions are estimated from the temperature dependence of the correlation time. Differences in the 13C line widths for individual carbons of polyisobutylene are discussed briefly.
Energy storage in drag‐reducing polymer solutions
Authors: Kohn Michael C.
Published: April 2003

A new theory, which relates viscous drag reduction to the energy stored by polymer molecules subjected to a fluctuating wall shear rate, is proposed for the origin of the Toms effect. The strain energy densities of several polymer solutions were estimated from bead‐spring theory. The requisite molecular polymers were optimized by a least‐squares fit of calculated to observed intrinsic viscosities. Friction reduction was found to be a monotonic function of the strain energy density for a given polymer–solvent combination. The correlation was independent of molecular weight and concentration for pipes of 0.5–2.0 in. diameter. Differences between the points of onset of drag reduction for different polymer–solvent combinations may be due to the unequal effect of internal viscosity.
Thermal fracture of plastics
Authors: Cross A. , Haward R. N.
Published: April 2003

The extension and fracture under tension of poly(vinyl chloride) strips of different lengths have been studied. It was found that, in spite of decreasing strain rate, long pieces are subject to a type of brittle fracture (necking rupture) occurring immediately after neck formation. This result, which could be expected from previous work, is shown to depend on the elastic energy stored in the longer test pieces. This energy is converted to heat under conditions of neck formation, leading to a temperature rise of 24 ± 4°C, determined by a thermal imaging system. With short test pieces the rise in temperature is much smaller, and a transition to stable neck propagation occurs. Optical and electron micrographs provide additional evidence of heating at the fracture surface. A semiquantitative treatment of the adiabatic process gives upper and lower limits for the predicted temperature change neglecting thermal losses. It is also possible to estimate a minimum length for the initiation of adiabatic deformation. Both calculations give results in reasonable agreement with experiments. Observations with polycarbonate show a similar length effect at low temperatures.
Crystallization‐induced reactions of copolymers. IV. Ester‐interchange reorganization of poly(ethylene terephthalate‐co‐2‐methylsuccinate)
Authors: Lenz R. W. , Go S.
Published: April 2003

The application of ester‐interchange reactions to the crystallization‐induced reorganization of random to block copolymers, which was demonstrated in the previous paper of this series, was followed quantitatively in this investigation. Structural changes based upon dyad compositions in copolyesters of terephthalic acid and 2‐methylsuccinic acid with ethylene glycol were determined by high‐resolution NMR. Sequence length distributions so calculated were related to the effects of copolymer composition, catalyst concentration, and reaction temperature on the rate of the ordering process and to the effect of structure on crystalline properties.
Simultaneous polymerization and formation of polyacetylene film on the surface of concentrated soluble Ziegler‐type catalyst solution
Authors: Ito Takeo , Shirakawa Hideki , Ikeda Sakuji
Published: April 2003

A direct method of simultaneously polymerizing and forming acetylene monomer to produce uniformly thin films of polyacetylene was investigated in terms of catalyst system, catalyst concentration, and polymerization temperature. The best catalyst was a Ti(OC4H9)4–Al(C2H5)3 system (Al/Ti = 3–4) and the critical concentration was 3 mmole/l. of Ti(OC4H9)4. Below the critical concentration, only a solid or a powder was obtained. The configuration of the polymers obtained depends strongly upon the polymerization temperature. Thus an all‐cis polymer was obtained at temperatures lower than −78°C, whereas an all‐trans polymer resulted at temperatures higher than 150°C. Observations either in an electron microscope by direct transmission or in a scanning electron microscope showed that the film is composed of an accumulation of fibrils about 200–300 Å in width and of indefinite length.
Photoreactions of N‐vinylcarbazole induced by metal salts. II. Further studies on the photocationic polymerization sensitized by sodium chloroaurate(III) in nitrobenzene
Authors: Asai Michihiko , Tazuke Shigeo , Okamura Seizo
Published: April 2003

Further investigations of the photopolymerization of N‐vinylcarbazole(VCZ) sensitized by sodium chloroaurate(III) in nitrobenzene were undertaken under irradiation of near‐ultraviolet light at 30°C. Copolymerization with isobutyl vinyl ether and the kinetic behavior of polymerization were studied. These propagation and chain‐breaking features were discussed in comparison with those obtained in the thermal polymerization. Electron spin resonance spectroscopy was conducted at 77°K in various systems.
Radiation‐induced emulsion polymerization of ethylene. II. Effect of potassium myristate concentration and dose rate on the rate of polymerization in connection with polymer properties, kinetics, and mechanism
Authors: Senrui Shiro , Suwa Takeshi , Takehisa Masaaki
Published: April 2003

Radiation‐induced emulsion polymerization of ethylene with potassium myristate as an emulsifier was studied in connection with the kinetics and the mechanism. The molecular weight of polymer was relatively low, of the order of 103, when a sufficient amount of emulsifier was used. However, polyethylene gel was produced in the absence of a sufficient amount of emulsifier. The rate of polymerization was proportional to the 0.5 power of dose rate and increased slightly with increasing emulsifier concentration. The rate of seeded polymerization followed a similar trend to that for conventional polymerization. Kinetic analysis of these results suggests that the escape of radicals produced by chain transfer of propagating radical with the emulsifier and the monomer from polymer particles into the aqueous phase plays an important part in the rate of polymerization. The melting temperature and the crystallinity of the polymer significantly decreased with increasing polymerization temperature in the range 40–60°C.
Radiation‐induced emulsion polymerization of ethylene. III. Emulsion polymerization with ammonium perfluorooctanoate as the emulsifier
Authors: Senrui Shiro , Suwa Takeshi , Takehisa Masaaki
Published: April 2003

Radiation‐induced emulsion polymerization of ethylene with ammonium perfluoro‐octanoate as an emulsifier was studied in order to elucidate the effect of the number of polymer particles. Owing to the stable structure of the emulsifier from a radical attack, no CF bond was detected in the polyethylene as expected. The polyethylene produced was mostly gel containing a small amount of low molecular weight polyethylene. This may be attributable to chain transfer to the polyethylene. The effects of dose rate and of concentration of the emulsifier were determined without considering the chain‐transfer reaction to the emulsifier. By considering the escape of the radical which is produced by chain transfer to the monomer from the polymer particle to the aqueous phase at the steady state, the following equation is derived:

The experimental results could be explained by this equation, and the apparent rate constants were obtained.
Anionic polymerization initiators containing protected functional groups and functionally terminated diene polymers
Authors: Schulz D. N. , Halasa A. F. , Oberster A. E.
Published: April 2003

Organolithium reagents substituted with hydroxyl‐carrying mixed acetals (i.e., tetra‐hydropyranyl and α‐ethoxyethyl ethers) have been prepared in high yields and used to polymerize 1,3‐butadiene to various acetal‐terminated polybutadiene polymers. A method is described for converting acetal‐containing polymers into hydroxyl‐containing polymers. The polybutadienes have been characterized with regard to endgroup types, quantitative functionalities, molecular weights, molecular weight distributions, and microstructures. Dihydroxyl terminated polymers are prepared anionically in the absence of gel. Such materials are more suitable from the standpoint of f(OH) and M̄w/M̄n for chain extension studies than are prepolymers prepared by radical methods.
Reaction of polyamine polymer with molecular iodine via charge‐transfer complex formation
Authors: Tomono Tsugikazu , Hasegawa Etsuo , Tsuchida Eishun
Published: April 2003

The reaction of a Mannich base type‐polyamine polymer with iodine (I2) was studied kinetically and thermodynamically in order to clarify the polymer effects in the formation of triiodide ions (I3−). N,N‐Dimethyl‐p‐(4‐methylpiperazinomethyl) aniline and 1,4‐dimethylpiperazine were used as low molecular weight donor model compounds. Triiodide ions are produced from the polyamine–I2 system immediately after mixing the two‐component solutions, while in the systems with I2 and N,N‐dimethyl‐p‐(4‐methyl‐piperazinomethyl)aniline and 1,4‐dimethylpiperazine they are obtained only when relatively high concentrations of both donor and acceptor solutions were mixed. This is explained by the entropic contributions of the polymer chain such as the stacking effect of donor nitrogen atoms, i.e., the increment of local donor concentration around I2 in the reaction field. The relation between the solution behavior of the reaction systems and the rate of formation of I3− ions also supports this kind of polymer effect. The effects of neighboring groups and dielectric constant on the reaction are also discussed.
Processability characteristics of chlorinated poly(vinyl chloride)
Authors: Krishnan M. , Singh Parkash , Thampy R. T. , Gupta V. B.
Published: April 2003

Chlorinated poly(vinyl chloride) (CPVC) is known to have a higher softening temperature than conventional poly(vinyl chloride) (PVC). Its processability characteristics are, however, different; it has been reported that CPVC is more difficult to process. However, only limited information on the processability characteristics is available. This paper describes some studies of the flow behavior of CPVC melts in a capillary rheometer. The true melt viscosity and activation energy were determined between 190° and 210°C for a number of samples, and they appear to be related to the cohesive energy density of the samples. It was observed that melt fracture, i.e., gross distortion of the extrudate, occurs even at low shear rates in samples having a high chlorine content. This has been attributed to the relatively high pressures that have to be used, the pronounced non‐Newtonian nature of the melt, and melt elasticity. It is postulated that melt elasticity could result from crosslinking at the site of the double bond which is known to be formed by dehydrochlorination.
Formation and flocculation of graft copolymer micelles
Authors: Horii Fumitaka , Ikada Yoshito , Sakurada Ichiro
Published: April 2003

Criteria for formation and flocculation of micelles from pure graft copolymers were investigated in single selective solvents by turbidimetry with the use of two series of graft copolymers from poly(vinyl acetate) (PVAC), i.e., PVAC–styrene graft copolymers with one branch and PVAC–methyl methacrylate graft copolymers with one and several branches. These graft copolymers could be completely coagulated through two processes in the selective solvents which had widely different ⊖ temperatures. The first process is the formation of micelles. One sequence, i.e., either backbone or branch of the graft copolymers, becomes desolvated under conditions similar to those for the corresponding homopolymer. This results in formation of the core of the micelle, the other soluble sequence extending from the surface of the core into the solvent phase. As the soluble chains cover the micelle core, no macroscopic phase separation occurs, but a stable dispersion is formed. The second process is that the micelle becomes too unstable to exist as dispersed when the solvency of the medium for the soluble sequence decreases to a certain degree. As a result, flocculation of the micelle finally takes place.
Effect of chain interpenetration on polymer–polymer interaction in solution
Authors: Worsfold D. J.
Published: April 2003

Two series of monodisperse polystyrenes have been prepared with a molecular weight range of 3,000 to 300,000. One series was lightly substituted with dimethylbenzylamine groups, the other with 2,6 dinitro‐4‐benzoyloxyphenol groups. Members of each series were dissolved together in benzene solution in the range of 0.1–30%, and the equilibrium constant for the formation of the ammonium phenolate ion pair measured. Also measured was the corresponding equilibrium constant between comparable small molecular weight analogs, and between these analogs and the substituted polymers. The degree of association found between the models and between the models and the polymers was independent of molecular weight, but deviations were found in the polymer–polymer interaction. Normal equilibrium constants were found at high polymer concentrations indicating that chain interpenetration occurred freely. At low concentrations of polymer, if several links per chain were possible it was found an excess of linkages were formed. If only one link per chain was possible, low degrees of association were found for high molecular weight polymers, but the effect was not as large as a consideration of excluded volumes on a spherical model would predict.
Synthesis of polymers by using divalent metal salts of mono(hydroxyethyl) phthalate: Metal‐containing polyurethanes
Authors: Matsuda Hideaki
Published: April 2003

As difunctional compounds containing an ionic bond in the molecule, divalent metal salts (I) of mono(hydroxyethyl) phthalate were prepared in high purity and high yield. Mg and Ca were selected as divalent metal.
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Metal‐containing polyurethanes containing ionic links in the main chain were synthesized by the polyaddition reaction of I or, I–glycols with diisocyanates. The polyurethane obtained were glassy materials or white powders, depending on the species of diisocyanates and glycols. Close agreement between observed and calculated values of metal content of the polyurethanes were obtained. The viscosities (in dimethyl‐formamide) of the polyurethanes decreased markedly with increasing of metal content. Moreover, the decomposition temperatures were lowered by introduction of metals into the polyurethanes. However, the decomposition rates of metal‐containing polyurethanes were lower than those of polyurethanes not containing metal.
Synthesis of polymers by using divalent metal salts of mono(hydroxyethyl) phthalate: Metal‐containing polyurethane‐ureas
Authors: Matsuda Hideaki
Published: April 2003

A series of metal‐containing polyurethane‐ureas containing ionic links in the main chain was synthesized by the polyaddition reaction of hexamethylene diisocyanate with mixtures of metal salts of mono(hydroxyethyl) phthalate and bisureas containing two hydroxyl groups which were obtained from monoethanolamine and diisocyanates. The polyurethane‐ureas obtained were generally yellowish powders or solids. Close agreement between observed and calculated values of metal content of the metal‐containing polyurethane‐ureas was obtained. The viscosities (in dimethylformamide) of polyurethane‐ureas decreased markedly with increase of metal content. Moreover, the decomposition temperatures were lowered a little by introducing metals into the polyurethane‐ureas. Dimethylformamide, m‐cresol, and dimethyl sulfoxide were comparatively good solvents for the metal‐containing polyurethane‐ureas; however, the polymers were insoluble in all other solvents.
Radiation degradation of poly(2‐methylpentene‐1 sulfone)
Authors: Bowden M. J.
Published: April 2003

Poly(2‐methylpentene‐1 sulfone) underwent random chain scission upon exposure to 1 MeV electron irradiation followed by extensive depropagation from the broken ends of the chain. Above 100°C, both sulfone and aliphatic peaks in the infrared spectrum disappeared at equal rates. An investigation of the kinetics suggested that the chains completely unzip. Below 100°C the initial rate of loss of SO2 was faster than loss of the aliphatic moiety.
Reactions and wetting properties of 1:1 perfluoroalkyl allyl and methallyl ether–maleic anhydride copolymers
Authors: Pittman A. G. , Wasley W. L. , Sharp D.
Published: April 2003

Polymers with fluoroalkyl side‐groups on three of every four carbon atoms along the polymer main chain were made by treating 1 : 1 copolymers of perfluoroallyl (or methallyl)ethers and maleic anhydride with SF4, and then esterifying the resulting acid fluoride groups with 1H, 1H‐pentadecafluorooctanol. Surface wettability of these polymers by polar and non‐polar liquids was studied. The critical surface tension (γc) was found by Zisman's method. The dispersion force component of polymer surface energy (γsD) and the polar component of surface energy (γsp) were calculated by the respective methods of Fowkes and Owens. The γc values for several of the highly fluorinated polymers were lower than previously reported for any fluoropolymer but not so low as has been observed for the surface of an oriented perfluoroacid monolayer. In the range 11.4–18.5 dyne/cm, γc approximates γsD for the fluorinated surfaces; however at lower γc values, considerable difference between γc and γsD was noted.
Poly‐1‐acryloylbenzotriazole as polyester and polyacrylamide precursor
Authors: Ferruti Paolo , Feré Angelino , Cottica Giovanni
Published: April 2003

1‐Acryloylbenzotriazole was prepared and polymerized. The resulting poly‐1‐acryloylbenzotriazole gave pure polyacrylic esters and polyacrylamides by reaction under mild conditions with alcohols and amines.
High temperature polymers. II. High temperature polymers from 4,4′‐[sulfonylbis‐(p‐phenyleneoxy)]dianiline
Authors: Brode George L. , Kawakami James H. , Kwiatkowski George T. , Bedwin Albert W.
Published: April 2003

Novel aromatic diamines have been prepared which contain an ordered sequence distribution of thermally stable, flexible, or rigid units. The synthesis of these materials involves a nucleophilic displacement reaction in aprotic solvent with, for example, the alkali metal salt of p‐aminophenol, optionally, the salt of a bisphenol and an activated aromatic halide. Such monomers are useful “building blocks” for various polymeric systems but are of special interest in those which can benefit from the high glass transition temperature imparted by polar or rigid moieties, together with improved impact properties conveyed by either groups. Polyimides and polyamide‐imides are examples and display high heat distortion temperatures, good solvent resistance, excellent mechanical properties, high thermal and oxidative stability and depending on diamine structure and molecular weight, thermoplastic characteristics. The synthesis and properties of polyamides, polyimides and polyamide‐imides based on 4,4′‐[sulfonylbis(p‐phenyleneoxy)] dianiline are presented in this paper.
High temperature polymers. III. Diphenyl sulfone‐based polyamide‐imides
Authors: Kwiatkowski George T. , Brode George L. , Kawakami James H. , Bedwin Albert W.
Published: April 2003

High temperature thermoplastic polyamide‐imides were prepared from a new series of aromatic diamines containing the diphenylsulfone unit and alternatively, oxydiphenyl and diphenylisopropylidene units. The polymers were prepared in their completely imidized form by using a facile in situ chemical imidization reaction which offers several advantages over the conventional thermal imidization process. The sulfone‐based polyamide‐imides exhibited an excellent combination of moldability, thermal stability, mechanical properties and solvent resistance. Analysis of the properties of these polymers in terms of structural variations permits a useful correlation of the effect of various structural units on performance. The polar diphenyl sulfone and amide‐imide units increase the glass transition temperature and improve solvent resistance while the oxydiphenyl and diphenylisopropylidene units improve thermoplasticity. Sulfone ether diamine polyamide‐imide (VI) offers the best combination of high temperature performance and moldability.
Aromatic polyethers, polysulfones, and polyketones as laminating resins. II
Authors: Sivaramakrishnan K. P. , Marvel C. S.
Published: April 2003

1,3‐Bis(p‐phenoxybenzenesulfonyl)benzene and 4,4′‐bis(p‐phenoxybenzenesulfonyl)‐diphenyl ether were polymerized with isophthaloyl and terephthaloyl chloride in Friedel‐Crafts type polymerizations. These polymers had 5‐cyanoisophthaloyl units in the backbone, obtained by using 5‐cyanoisophthaloyl chloride as part of the acid chloride monomer. A number of catalysts were screened to effect the trimerization of the pendant nitrile groups in the polymer to the triazines. Model reactions were carried out for each polymer. Physical and thermal properties of the laminates obtained from these polymers are discussed.
Stereochemical regulation of polypropylenes prepared with various Ziegler‐Natta catalysts
Authors: Mitani Katsuo , Suzuki Toshimitsu , Matsuo Akihiro , Takegami Yoshinobu
Published: April 2003

The 220‐MHz proton magnetic resonance and infrared spectra of stereoregular polypropylenes polymerized with a number of Ziegler‐Natta catalysts and isotactic polymers of low molecular weight obtained by thermal degradation of a highly isotactic polypropylene were measured in an attempt to obtain some information on the local regularity. The fraction of thermally degraded polymer soluble in diethyl ether shows stereorandomness (tactie sequence length is quite short), and the portion soluble in n‐pentane has stereoblock character. The results so obtained provide strong evidence that racemic dyads of whole polymer consist of two models of racemic dyad isolated and racemic dyads in groups. The polymers prepared with vanadium catalyst systems show stereorandom character and these polymers have \documentclass{article}\pagestyle{empty}\begin{document}$\hbox{-\hskip-1pt-}\hskip-4pt({\rm CH}_2 \rlap{--} )$\end{document} groups formed by two propylene units in a tail‐to‐tail linkage. Syndiotactic polypropylene has head‐to‐head and tail‐to‐tail arrangements of two propylene units and this is the origin of randomness of syndiotacticity.
Photoinduced polymerization of maleic anhydride in dioxane
Authors: Nagahiro Isao , Nishihara Koji , Sakota Naokazu
Published: April 2003

Maleic anhydride (MAn) was irradiated with ultraviolet light in dioxane at 35°C without initiator, and predominantly a MAn oligomer was obtained with a small quantity of cyclic dimer of MAn. Mass spectrometric, NMR, and elementary analysis investigation of the oligomer showed that it is composed of about four MAn units and one dioxane molecule per molecule.
Determination of crystallinity in polycaproamide fibers by the method of half‐integral intensity
Authors: Włochowicz A. , Jeziorny A.
Published: April 2003

The rectilinear relationship between the integral intensity Bi and fiber density d is used as the basis of a new method for evaluation of the crystallinity index of polyamide fibers (PA‐6). To calculate the value of the crystallinity index of the fibers one should have the integral intensity value of the sample and the integral intensities of crystalline and amorphous samples determined under defined instrumental conditions. The method provides a quick and simple means for determining the crystallinity. The method of half‐integral intensity may be used only with care when the α‐monoclinic polymorphic form dominates in the PA‐6 fiber.
Synthesis of zirconium poly‐O‐amidoximes
Authors: Carraher Charles E. , Frary Ronald A.
Published: April 2003

Synthesis of zirconium poly‐O‐amidoximes was affected by using both interfacial and aqueous solution techniques.

Reaction is rapid. The yield for the synthesis of analogous titanium product is Cp2ZrCl2 > Cp2TiCl2 which is consistent with that predicted by the hard‐soft acid–base theory.
Cyclopolymerization. II. Mechanism of the free‐radical polymerization of N‐n‐propyldimethacrylamide
Authors: Kodaira Toshiyuki , Aoyama Fumio
Published: April 2003

The mechanism of cyclopolymerization was investigated by using N‐n‐propyldimethacrylamide (PDMA). Completely cyclized polymers were formed on polymerization of PDMA by a radical initiator. Moreover, those copolymers of PDMA and various monomers, such as styrene, methyl methacrylate, and vinyl acetate, obtained did not contain any detectable pendent double bonds. The kinetic investigation showed that the termination reaction proceeded between the cyclized radicals. The attempted polymerization of N‐n‐propyl‐N‐isobutyrylmethacrylamide, the monofunctional counterpart of PDMA, was failed. These results appear to confirm that cyclopolymerization of PDMA proceeds through a concerted mechanism which has been proposed for the mechanism of the cyclopolymerization of various difunctional monomers. Measurement of the ESR spectra of propagating radical has, however, revealed that the rate‐determining step of the cyclopolymerization of PDMA is not intermolecular propagation but intramolecular cyclization, which indicates that the cyclization reaction proceeds in a stepwise way. This apparent contradiction was explained based upon thermodynamic considerations.
H2O2‐photosensitized emulsion copolymerization of tetrafluoroethylene with propylene
Authors: Suzuki Nobutake , Okamoto Jiro
Published: April 2003

The H2O2‐photosensitized emulsion copolymerization of tetrafluoroethylene with propylene was carried out at room temperature in the presence of gaseous monomers of 50 mole‐% tetrafluoroethylene content. The conversion increased almost linearly with irradiation time. The rate of polymerization was proportional to the 1.0 power of H2O2 concentration up to 3.5 × 10−3M H2O2 and the 0.46 power of H2O2 concentration above 3.5 × 10−3M H2O2. The result obtained at low H2O2 concentration was almost consistent with that obtained in the radiation‐induced method. The rate of polymerization was proportional to the 0.58 power of the emulsifier concentration, and the degree of polymerization was independent of the emulsifier concentration. The H2O2‐photosensitized emulsion copolymerization of tetrafluoroethylene with propylene is terminated mainly by degradative chain transfer of the propagating radical to propylene at low H2O2 concentration and by the reaction of the propagating radical with OH radical from photolysis of H2O2–aqueous solution at high H2O2 concentration.
Cyclotrimerization of acetylene by the tris(acetylacetonato)titanium(III)–diethylaluminum chloride system
Authors: Shirakawa Hideki , Ikeda Sakuji
Published: April 2003

Reaction of acetylene with tris(acetylacetonato)titanium(III) and diethylaluminum chloride system leads to formation of benzene, a trace of ethylbenzene, and a small amount of polyacetylene. The isotopic composition of products obtained from cyclotrimerization of acetylene‐d2 and an equimolar mixture of acetylene and acetylene‐d2 is investigated to elucidate the mechanism of the cyclotrimerization. The results suggest a mechanism in which an acetylene inserts into the metal—ethyl bond formed by reaction of Ti(acac)3 and Al(C2H5)2Cl, followed by insertion of two acetylene molecules and elimination of a hydrogen atom from the first inserted acetylene to yield an ethylbenzene and a metal hydride intermediate. The metal hydride intermediate catalyzes acetylene cyclotrimerization to give benzene. During the reaction, the hydrogen atom in the metal hydride intermediate does not exchange with the hydrogen atom in the inserted acetylene molecules.
Energy transfer processes involving ultraviolet stabilizers: Nickel dibutyldithiocarbamate in polypropylene films
Authors: Guillory J. P. , Becker Ralph S.
Published: April 2003

The energy transfer behavior of an ultraviolet stabilizer, nickel dibutyldithiocarbamate (BTN), is examined in solution and in thin polypropylene films. The rate of photosensitized dissociation of this nickel chelate by 4‐methyl‐2‐pentanone in solution was found to be approximately ten times that of its photodissociation after direct ultraviolet excitation. The rate of photodissociation of BTN in preoxidized polypropylene films was also measured. It was found that BTN does not quench the excited carbonyl groups in degassed polymer films. These results are compared to those for nondegassed preoxidized polypropylene samples and are discussed in terms of singlet oxygen quenching. A phenolic antioxidant was found to have no effect on the photodissociation of BTN in either degassed or nondegassed polypropylene films.
Stereoelective polymerization of tert‐butyl thiirane
Authors: Dumas Philippe , Spassky Nicolas , Sigwalt Pierre
Published: April 2003

The polymerization in bulk of racemic tert‐butyl thiirane with a chiral initiator resulting from the reaction between diethylzinc and ()3,3‐dimethyl‐1,2‐butanediol produces an optically active polymer by preferential consumption of R enantiomer. The unreacted monomer is enriched in S enantiomer. The relative rate r of consumption of R enantiomer versus S enantiomer is as high as 2.8. Obtained polymer could be separated into two crystalline fractions: an optically active fraction, formed from regular sequences of R type enantiomeric units, and an optically inactive fraction which corresponds to a racemate. Experimental results are consistent with a stereospecific mechanism of addition, the two enantiomers being chosen by two different type of sites. The stereoelective process is due to an unequal number of these two types of sites.
Near‐infrared spectrum of cellulose: A new method for obtaining crystallinity ratios
Authors: Basch A. , Wasserman T. , Lewin M.
Published: April 2003

Absorption bands in the near‐infrared (NIR) spectrum of cellulose were correlated with crystalline and noncrystalline regions and used to derive a new crystallinity ratio. NIR crystallinity ratios of both natural and regenerated celluloses were measured and compared with x‐ray diffraction values. The data indicates that the NIR crystallinity ratio may also depend upon crystallite size.