bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of intrinsic viscosity data
Authors: Kawai Tōru , Kamide Kenji 
Published: April 2003

AbstractIn order to interpret quantitatively intrinsic viscosity data for polymer solutions, especially for chains of poor flexibility, the partially free draining effect discussed in the theories of Kirkwood and Riseman and Debye and Bueche must be also taken into account, as well as the excluded volume effect considered in the theory of Flory and Fox. Although the Flory‐Fox theory is widely used at present for analysis of intrinsic viscosity data, it appears that in most actual cases the draining effect may also play an important part and the two effects may overlap each other to some extent. A new method has been presented in this paper, through which the separation of these tow contributions becomes possible. The exponent a in the Mark‐Houwink equation, [η] = KmM̄va, is divided into two parts: a1, related to the volume effect, and Δ, related to the draining effect. Making use of the theoretical relationship between Km and a, which was derived in the preceding paper, we can calculate the value of Δ, if the Mark‐Houwink constants have been established for a given series of polymer homologues in two solvents. In this way, we can discuss the volume effect and the draining effect separately, and interpret completely intrinsic viscosity data in terms of the parameters appearing in the Flory‐Fox and Kirkwood‐Riseman theories. Furthermore, a new method has been proposed for estimating the Mark‐Houwink constants from the measurements of intrinsic viscosity and molecular weight for a single sample. Only one sample need be used, and thus recourse to the usual more laborious methods is unnecessary. General applicability of our methods has been shown by several examples cited from published data.
Diffusion of gases and vapors through polyvinyl chloride–polyvinyl acetate copolymer films II. The effect of polymer segment mobility
Authors: Kumins C. A. , Roteman J. 
Published: April 2003

AbstractThe minimum free volumes involved in the diffusion of gases of various sizes through a copolymer of polyvinyl chloride–polyvinyl acetate have been calculated by use of equations developed by F. Bueche. It was found that as the gas diameter of the diffusant increased, the minimum free volume for diffusion increased exponentially. Bueche's modification of the Williams, Landel, and Ferry equation permitted use of the diffusion data to determine the number of polymer segments that cooperate in the diffusion process for each particular gas. The internal pressure of the polymer and the energy of activation for viscous flow were also calculated from the gas diffusion data. A discussion of the results is given.
Birefringence in a strained viscoelastic fluid under steady‐state rotary conditions. II
Authors: Gill Stanley J. , Dintzis Frederick R. 
Published: April 2003

AbstractA rotary strain device for introducing a calculable amount of strain into a viscoelastic fluid under essentially zero flow conditions has been built and tested. The principle of the device is based upon the continuous deformation of a flexible Teflon tube which is rotated within a closely fitting, stationary, rigid metal tube that has an elliptical cross section. A polymer solution placed in such a rotating tube is subjected to an alternating strain and rotation of the bulk material. Under such conditions a steady‐state situation occurs where the material has well defined anisotropic properties. This anisotropic state is characterized by measuring both the retardation and orientation of the principle axes of the induced birefringence with a Soleil Babinet compensator. Measurements made on fluid systems at rotations of approximately 50–400 rpm yield experimental results that agree with general theoretical requirements. Mooney has analyzed the analogous situation of a microscopic rotating region. This analysis, when applied to measurements made in the rotary strain device, permits calculation of functions proportional to the storage modulus, the loss modulus, and the relaxation function of the polymer. Measurements and calculations are presented for carboxymethyl cellulose solutions in water.
The catalyst‐forming reaction between trimethylaluminum and titanium trichloride
Authors: Rodriguez L. , Gabant J. 
Published: April 2003

AbstractExperimental data and a reaction scheme concerning the reaction between TiCl3 and Al(CH3)3 are presented. The reaction yielding a polymerization‐active catalyst was studied in the absence of a solvent, predominantly at 65°C. The conclusion is drawn that about half of the carbon present on the catalyst is in the form of easily exchangeable CH3 groups.
New polyelectrolytes: Synthesis and preliminary characterization
Authors: Blatz P. E. 
Published: April 2003

AbstractMethacryloyl chloride was polymerized in a solvent mixture of benzene and cyclohexane. The degree of polymerization was determined for the methyl ester in acetone. Solid amino acids and hydroxy acids were added to the poly(methacryloyl chloride), and the insoluble polyelectrolytes that formed were separated and purified in selected solvents. In this manner derivatives of glycine, p‐aminobenzoic acid, sulfanilic acid, β‐alanine, and glycolic acid were prepared. The resulting polyelectrolytes were subjected to acid and base hydrolysis. The amide bonds showed considerable stability while the imide bonds were readily hydrolyzed. The results of elemental analysis, degree of hydrolysis, infrared analysis, and titration are used to arrive at a qualitative description of the structures.
Thermal degradation of polymers. I. Aspects of polytetrafluoroethylene degradation
Authors: Goldfarb I. J. , McHenry R. J. , Penski E. C. 
Published: April 2003

AbstractThe mechanism of the thermal degradation of polytetrafluoroethylene is investigated. It is shown that the chain transfer reaction should not be ignored and that a reasonable explanation for the observation that monomer is almost the exclusive product of vacuum thermal degradation is the rate of diffusion and volatilization of larger fragments from the polymer. Diffusion of tetrafluoroethylene and hexafluoropropylene through polytetrafluoroethylene was studied. The diffusivities are 72 and 39 × 10−10 cm.2/sec. for C2F4 and C3F6, respectively, at 24°C. An apparatus for measuring the weight and temperature of degrading polymers under vacuum is also described.
Thermally stable salts of polyvinylphthalic acid
Authors: Winslow Eugene C. , Laferriere Arthur 
Published: April 2003

AbstractThe heretofore unreported monomer 4‐vinylphthalic acid has been synthesized and characterized. Polymerization in aqueous solution employing a peroxydisulfate–hyposulfite redox catalyst system yielded glasslike polyvinylphthalic acid. Molecular weights of polyvinylphthalic acid appear to be in the range of 104–105. Alkaline earth polyphthalates show thermal stability to temperatures of 560°C. for periods of approximately 1 hr. Phthalocyanine crosslinks can be formed between chains of polyvinylphthalic acid, but such polymers do not show remarkable thermal stability.
Persistent polarization in poly(vinylidene fluoride). III. Depolarization and pyroelectricity of poly(vinylidene fluoride) thermoelectrets
Authors: Murayama Naohiro , Hashizume Hideyuki 
Published: April 2003

AbstractPersistent polarization in poly(vinylidene fluoride) thermoelectrets prepared under high electric field has been studied by measurements of depolarization and pyroelectricity. Various polarizations are examined in detail; the polarizations related to a characteristic molecular motion near 60°C and the polarizing temperature are not responsible for the major piezoelectric effect in β‐form electrets. The piezoelectricity is attributed to a polarization appearing near the melting temperature. The persistent polarization corresponding to d31 of 2 × 10−11 coul/N is about 5 × 10−6 coul/cm2. The pyroelectricity of β‐form electrets is linearly correlated with the piezoelectricity.
Application of semiempirical melting formulas to the melting of polymer crystals
Authors: Bohlin L. , Kubát J. 
Published: April 2003

AbstractThis paper discusses the applicability of three melting equations to the melting temperature and its pressure dependence in polymer crystals. The equations considered are the empirical Simon equation and two semiempirical equations, the Lindemann equation and the anharmonic potential barrier equation (APB equation). It was found that although the Simon equation fits melting curves of polymeric solids well, it is merely an interpolation and extrapolation formula. There appears to be no correspondence between theoretical and experimental values of the exponent in the Simon equation. With regard to the melting temperature at atmospheric pressure, the APB and Lindemann equations perform equally well. Using the value 3.5 for the universal Grüneisen constant, it is shown that T (Lindemann) = 1.07 T (APB). On the other hand, the different physical arguments behind the two approaches lead to a very different behavior at high pressures. For the predicated initial change of melting temperature with increasing pressure a ratio close to 5:1 is obtained between the APB and the Lindemann equation. For high‐density polyethylene the Lindemann equation yields a melting temperature of 470°K when θ3 = 112°K given by Wunderlich is substituted for the Debye temperature. The observed melting temperature 405°K Corresponds to a Debye temperature of 107°K. The increase of the melting temperature with pressure for high‐density polyethylene is predicted as 31°K/kbar by the Lindemann equation as compared with 23°K/kbar found by experiment.
Comparison of head‐to‐head and head‐to‐tail polystyrenes by thermally stimulated discharge
Authors: Marchal E. , Benoit H. , Vogl O. 
Published: April 2003

AbstractThermally stimulated depolarization (TSD) experiments were carried out on several polystyrene samples. They included normal head‐to‐tail polystyrene (atactic) obtained by anionic polymerization of styrene, amorphous and substantially crystalline isotactic polystyrene, and the newly available head‐to‐head polystyrene. By TSD, six maxima of current intensity occurred at specific temperatures. Their features are compared for the various samples. Only three peaks could be identified with transitions which had been found by other techniques. Peak 5, located near Tg, is the primary relaxation. Maximum 6 could be the transition found above the Tg by torsional braid analysis and called T11 for polystyrene samples. Maximum 1 seems to correspond to what is sometimes referred to as the γ transition.
Small‐angle x‐ray scattering and crystallization kinetics of poly(ethylene terephthalate) crystallized in a liquid environment
Authors: Makarewicz P. J. , Wilkes G. L. 
Published: April 2003

AbstractBy small‐angle x‐ray scattering, a systematic investigation was performed of the long spacing of poly(ethylene terephthalate) (PET) crystallized in a liquid environment. The results indicated that the measured long spacings were temperature dependent and apparently relatively insensitive to liquid type under the conditions studied. The kinetic nucleation model of polymer crystallization was found to adequately explain this dependence. The differences in the long spacings between thermal and liquid‐induced crystallization were in part rationalized in terms of the suspected supercoolings involved in the respective processes. Calculation of the spherulite growth rates for liquid‐induced crystallization was made on the basis of the kinetic nucleation model and the classic theory of polymer–diluent crystallization. The results were shown to agree with inferential experimental observations of these growth rates and to elucidate the physics underlying liquid–induced crystallization. Finally, use of this growth rate theory in conjunction with a previous model for overall crystallization kinetics was shown to adequately describe and predict the diffusion‐limited kinetics observed experimentally for most liquid‐induced crystallization situations.
Model of sorption of simple molecules in polymers
Authors: Pace R. J. , Datyner A. 
Published: April 2003

AbstractA model of simple molecule sorption in polymers is proposed which embraces both the glassy and rubbery regions, and incorporates the successful dual‐mode model below the glass‐transition temperature. Hole filling is shown to be an important sorption mechanism both above and below Tg, although saturation effects do not occur in the rubbery polymer. The model interprets the “dual‐mode” Langmuir and Henry's law parameters at the molecular level, and a simple statistical mechanical analysis allows estimation of the parameter values, as well as specifying certain interrelationships between the parameters. Applications of the model to gas solubility data in five polymers are considered [polyethylene (PE), poly(ethylene terephthalate) (PET), polystyrene (PS), polymethacrylate (PMA), poly(vinyl acetate) (PVAc)] and semiquantitative agreement is obtained for PE, PET, and to a lesser extent, PS. For PMA and PVAc, the agreement is qualitative only.
Analysis of the products of copolymerization with chain branching in the pregelation stage
Authors: Mrkvičková Libuše , Kratochvíl Pavel 
Published: April 2003

AbstractThe copolymerization of methyl methacrylate with small amounts (0.25‐1 mol %) of bis (4‐methacryloxybenzilidene)‐1,2‐diaminoethane in the pregelation stage was investigated. The mole fractions in the copolymers of the divinyl monomer, of the reacted vinyl groups of divinyl monomer, and of the totally reacted divinyl monomer units forming intermolecular crosslinks were determined experimentally and some other parameters were calculated from these quantities. The amount of intramolecular crosslinks, forming closed rings, has been shown to predominate over the amount of intermolecular crosslinks. The comparison of the experimental data with values calculated from Wesslau's theory, based on the classical concepts of copolymerization, reveals differences increasing up to an order of magnitude with rising content of the divinyl monomer. A major reason for this divergence appears to be the intramolecular crosslinking.
Calculation of electronic band structures for some rigid benzobisoxazole and benzobisthiazole polymers
Authors: Bhaumik D. , Mark J. E. 
Published: April 2003

AbstractQuantum‐mechanical methods were employed to calculate electronic band structures for the polybenzobisoxazole (PBO) and polybenzobisthiazole (PBT) chains originally synthesized and much studied because of their utility as high‐performance fibers and films. For cis‐PBO, trans‐PBO, and trans‐PBT chains in their coplanar conformations, the band gaps in the axial direction were found to be 1.72, 1.62, and 1.73 eV, respectively. Since trans‐PBT is nonplanar, calculations on it were also carried out as a function of the rotation angle ϕ about the C—C bond joining the two +ing systems in the repeat unit. The band gap was found to increase markedly with increase in nonpla‐narity, as would be expected from the decrease in charge delocalization. The calculations suggest the most likely value of ϕ to be ca. 30°, in good agreement with the experimental value 23° obtained by x‐ray analysis of a crystalline trans‐PBT model compound. At this value of ϕ, the calculated value of the band gap is.1.98 eV. All of these values are very close to the corresponding values of 1.4‐1.9 eV reported for trans‐polyacetylene, which should encourage further theoretical and experimental investigations of the electronic properties of these polymers.
Properties of semidilute polymer solutions: Investigation of an optically labeled three‐component system
Authors: Cotts David B. 
Published: April 2003

AbstractA three‐component system containing a polymer (2), a good solvent (1) for that polymer, and a second polymer (3) that is compatible with component (2) and isorefractive with the solvent (1) has been studied by static and dynamic light‐scattering methods. In concentrated toluene (1) solutions of poly(vinyl methyl ether) (3), where appreciable chain overlap occurs and excluded‐volume effects are reduced, polystyrene (2) may be studied in the dilute‐solution limit. Consequently, these light‐scattering measurements provide an explicit measure of both thermodynamic and hydrodynamic changes that occur as the total polymer concentration is increased from dilute to concentrated solution. Precise numerical coefficients, correct scaling exponents, the radius of gyration, and the effective hydrodynamic radius can be measured directly along with the observation of long‐wave single‐chain reptation motions and short‐range cooperative motions in semidilute and concentrated solutions.
Fourier‐transform infrared studies of the thermal degradation of isotopically labeled polyacrylonitriles
Authors: Rafalko Joseph J. 
Published: April 2003

AbstractPoly(d3‐acrylonitrile), poly(1‐13C‐acrylonitrile), poly(15N‐acrylonitrile), and 18O2 have been used to assign the infrared spectra of the thermal degradation products of polyacrylonitrile. Isotopic data and elemental analyses show that the degradation products can be made free of oxygen. The infrared data suggest that the reaction proceeds sequentially from imines to fused pyridine‐dihydropyridine moieties.
Linear polymers in nonhomogeneous flow fields. I. Translational diffusion coefficient
Authors: Brunn P. O. , Grisafi S. 
Published: April 2003

AbstractThe translational diffusion coefficient D, needed in treatments of flow‐induced polymer migration phenomena, is studied. Explicit results are reported for bead–spring model macromolecules with two, three, and four beads, respectively. If the number of beads is large, an integral formulation is used. The results obtained show that D depends upon the hydrodynamic interaction parameters h* and h*N1/2. Nondraining behavior of D is predicted irrespective of h if h* is close to 0.2357. Approximations for D are obtained and the error involved is estimated.
Heat capacities of liquids linear aliphatic polyoxides
Authors: Suzuki Hidematsu , Wunderlich Bernhard 
Published: April 2003

AbstractHeat capacities at constant pressure of liquid polyoxymethylene (430‐540 K) and polyoxyethylene (330‐430 K) have been measured by scanning calorimetry. These new data are discussed together with the heat capacity of polyethylene and other linear, aliphatic polyoxides to arrive at a wide‐range addition scheme for heat capacities. Values of absolute entropy, enthalpy, and Gibbs free energy are estimated. The new data are offered as “Recommended Data 1984” in our ATHAS Data Bank.
Surface modification of contact‐lens materials by silanization: An FTIR‐ATR study
Authors: Khoo C. G. L. , Lando J. B. , Ishida H. 
Published: April 2003

AbstractThe adsorption, desorption, and orientation characteristics of two long‐chain chlorosilane compounds, octadecyltrichlorosilane and 1‐undecylene‐dimethylchlorosilane, onto poly(methyl methacrylate) (PMMA) and poly(2‐hydroxyl‐ethyl methacrylate) (PHEMA) are studied using Fourier‐transform infrared attenuated total reflection (FTIR‐ATR) spectroscopy. Quantitative monitoring of the amount of silane adsorbed is also attempted. It is believed that the surface modification reaction has been successfully confined to monolayer coverages and that sufficient detection sensitivity has been achieved to observe the reaction at these low levels on both PMMA and PHEMA. Also, ATR polarization studies indicate that on both substrates, a definite preference for orientation exists such that the long molecular axis is perpendicular to the substrate surface. The silanes are observed to be only physisorbed onto the PMMA surface under the anhydrous conditions applied during adsorption, whereas a chemical reaction is observed on the PHEMA surface.
Chemiluminescence from oxidation of polypropylene: Some comments on a kinetic approach
Authors: Billingham Norman C. , George Graeme A. 
Published: April 2003

AbstractWe present a detailed criticism of the kinetic approach to the analysis of data obtained from measurements of the very weak chemiluminescence accompanying the oxidation of polypropylene. It is shown that a kinetic model proposed by other workers is based upon invalid assumptions, leads to kinetic parameters which are not sensible, and requires measurement of the properties which it claims to predict.
Ion transport and states of water in charged poly(allylamine) membranes
Authors: Yonetake Koichiro , Seo Toshihiro , Iijima Toshiro 
Published: April 2003

AbstractCationically charged poly(allylamine) (PAA) membranes having various water contents [0.49 < H < 0.63 (g H2O/g wet membrane)] were prepared. Sorption and permeation of simple salts (sodium chloride and sodium tetraphenylborate) were investigated, taking into account the state of the water in these membranes. The weight ratios of freezable water and free water to total water (Wfz/Wt, and Wf/Wt) in the membranes were estimated by means of DSC and pulsed 1H‐NMR measurements, respectively. Partition coefficients K for total water were converted into those in freezable and free water, Kfz and Kf, using Wfz/Wt and Wf/Wt. The permeability of both salts in the membranes could be interpreted satisfactorily by an equation derived from the Teorell‐Meyer‐Sievers theory using values of Kf. The free water is mainly involved in the permeation of simple salts through PAA membranes while bound water hardly takes part.
The effects of physical aging in polycarbonate
Authors: Hill A. J. , Heater K. J. , Agrawal C. M. 
Published: April 2003

AbstractThe effects of physical aging below the glass transition temperature on selected properties of polycarbonate have been studied. Changes in tensile yield strength, post yield stress drop, and fracture toughness as a result of annealing at 120°C for 240 h have been measured and are related to changes in free volume as measured by positron annihilation lifetime spectroscopy. The free volume concentration remains constant during the aging heat treatment at 120°C but decreases after cooling due to aging. The relationship between free volume changes and physical property changes is discussed in terms of molecular conformations and fracture mode. The effect of aging on fracture morphology is presented to aid interpretations of fracture mode.
Electrical conductivity of cationic polyelectrolytes in aqueous solution
Authors: Ríos Hernán E. , Sepúlveda Luis N. , Gamboa Consuelo I. 
Published: April 2003

AbstractFour different fluoride, chloride, bromide, and nitrate cationic polyelectrolytes were prepared. Their electrolytic conductivity in aqueous dilute solution was investigated. The results show a remarkable increase, with dilution being practically constant down to limiting concentration. The limiting equivalent conductivity Λ° follows the order
$\[ {\rm F}^ - \gg {\rm Cl}^ - > {\rm Br}^ - \approx {\rm NO}_3^ - \]$
The distances between neighboring charges calculated from experimental data are in good agreement with those calculated geometrically according to Manning's definition. The results are mainly dependent on the assumption that Br− and NO3− interact in a similar manner with the cationic charges on the polyion. This phenomenon also has been observed in cationic micelles.