bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyblends. III. Correlation of the viscoelastic data for polyblends of NBR and plasticized vinyl chloride compositions with theories of polycomposite behavior
Authors: Jordan Edmund F. , Artymyshyn Bohdan , Riser George R. 
Published: April 2003

AbstractViscoelastic data obtained on the polyblends described in the previous two papers together with some new data have been correlated with various theories derived for the viscosity and continuum properties of polycomposites, to gain insight into the nature of compatible domain interactions. Unmodified theories of Mooney, Eilers and Van Dyck, Guth and Smallwood, and Kerner did not correlate with the observed viscoelastic data. However, when the Kerner relation was substantially altered (after allowing for phase inversion following procedures of Halpin and Tsai as modified by Nielsen), an adequate description of torsional modulus behavior at ambient temperature was obtained. To characterize tensile modulus (100%), however, a new expression was necessary. Both procedures invoked in a critical modulus for the blend with respect to composition at which phase inversion was initiated. The critical volume fraction associated with this modulus increased inversely with the Tg of the filler; when the filler Tg was below the ambient temperature, the blends behaved as mixed rubbers, and torsional modulus ratios followed the lower Kerner relation at all blend compositions. It was concluded that polyblends having isochronal modulus–temperature curves that shift with composition over the temperature scale yet are anomalously broad as in the present work should be classified as systems exhibiting restricted molecular mixing. The restricted molecular mixing character exhibited by the polyblends could be explained by a plurality of mixed‐phase responses to deformation produced in a morphology of interlocking microdispersions. Favourable polarity effects and high filler ductility were considered responsible for the domain interactions. No evidence was found for true molecular compatibility in the blends. An analysis of temperature effects on the blend viscoelasticity resulted in a temperature analog of the composition behavior.
Study on ozone treatment of water‐soluble polymers. II. Utilization of ozonized polyethylene glycol by bacteria
Authors: Suzuki Junzo , Nakagawa Hisako , Ito Haruo 
Published: April 2003

AbstractA bacterium capable of utilizing polyethylene glycol of low molecular weight (less than 300) was isolated from soil and identified as Pseudomonas aeruginosa by biologic characteristics (named P. aeruginosa PEG‐K). The effect of ozone degradation on the utilization of polyethylene glycol of high molecular weight by the bacterium was studied on the basis of the measurement of oxygen uptake by Warburg manometer and of bacterial growth. The polyethylene glycol, which can never be utilized at all because of high molecular weight, became utilizable by the bacterium as a result of ozonization, while the formaldehyde produced by the ozonization inhibited the utilization of the ozonized polyethylene glycol by the same bacterium. However, such inhibition disappeared by treating the aldehyde with hydrogen peroxide. From the results of gas chromatography and measurement of chemical oxygen demand, P. aeruginosa PEG‐K was found to utilize ethylene glycol, diethylene glycol, and triethylene glycol, which were produced by the ozonization.
An examination of the dow and NBS 705 polystyrene standards via gel permeation chromatography
Authors: Fetters L. J. 
Published: April 2003

AbstractAn examination of the molecular weight distribution via gel permeation chromatography of the Dow S‐109 and NBS 705 polystyrenes has revealed that these two samples are the same. Within experimental error, both polystyrenes possess identical number ‐and weight‐average molecular weights. In addition, the molecular characteristics of the Dow S‐102, Dow S‐105, Dow S‐108, and Dow S‐111 polystyrenes were determined. Of the samples examined, the near‐monodisperse NBS 705, Dow S‐102, Dow S‐109, and Dow S‐111 were found to have either low or high molecular weight components in their molecular weight distributions. The characterization results on the Dow S‐109 polystyrene fail, though, to explain the melt viscosity anomalies reported for this polymer.
Stoichiometrically solvated polyalkylbenzimidazole crystals
Authors: Aharoni Shaul M. 
Published: April 2003

AbstractUnlike most crystallizable polymers, some polyalkylbenzimidazoles do not crystallize when pure but do crystallize with ionized solvent molecules to produce solid stoichiometrical, solvated crystals. The polymer–solvent interaction is strongly exothermic, and a crosslinked polymer swells in the solvent over hundredfold. This leads to a negative χ1 value for the system. The cocrystallization with stoichiometric amounts of ionized solvent cannot be examined on the assumption that it is a polyelectrolyte gel since ion mobility is precluded. It also cannot be treated according to the corresponding states theory since the latter does not allow for negative χ1. A theoritical derivation, originating from Flory's semiflexible chain treatment, apparently predicts and explains the behavior of the polyalkylbenzimidazole–solvent system.
Aspects of vapor pressure osmometry
Authors: Morris C. E. M. 
Published: April 2003

AbstractThree aspects of vapor pressure osmometry were examined: drop size, solute volatility, and the constancy of the calibration factor. It was shown that there is a drop size effect which is dependent on the solute concentration. Solutes having vapor pressures as low as 0.3 mm Hg under the operating conditions were found to give unsatisfactory results. The calibration factor was determined using eight compounds in the molecular weight range of 128 to 883 in chloroform, toluene, and methyl ethyl ketone at several temperatures; a small but significant dependence of the calibration factor on molecular weight was demonstrated. The results fitted, with a high degree of accuracy, the relation log M̄n = a + b log (ΔV/C)C = 0, where a and b are constants for a given solvent/temperature combination. However, measurements with standard polystyrene samples, using extrapolations of this relationship to higher molecular weights, revealed considerable discrepancies in results for the one compound under different solvent/temperature combinations.
Gel permeation chromatography: Dispersion effects on molecular weight monitor‐installed gel permeation chromatograph
Authors: Kotaka Tadao 
Published: April 2003

AbstractComputer simulation was carried out to examine the performance of a molecular weight (MW) monitor‐installed gel permeation chromatograph (GPC), by taking account of the effects of limited column resolution according to Tung's phenomenological scheme. Efficiency of GPC fractionation was discussed also in the same light. For simulated GPC fractionation results of model polymers having log‐normal distribution, various average MW's and MWD functions were calculated from the data obtained by the MW monitor method as well as the conventional MW calibration methods, and compared with the given true values. The MW monitor method generally tends to predict narrower distributions than the true ones, as opposed to the conventional calibration methods which usually predict broader distributions. For certain simple cases, semiquantitative relation between the extent of column resolution and these deduced average MW's was derived. The efficiency of GPC fractionation (as judged, for example, by the polydispersity of recovered fractions) is limited by such factors as fraction size, column resolution, and polydispersity of the original sample itself.
Photosensitized degradation of polyolefins. II
Authors: Mantovani E. , Mazzei M. , Robertiello A. , Zanobi A. 
Published: April 2003

AbstractThe oxydative photodegradation of polyethylene sensitized by aromatically substituted dienes such as 1,6‐diphenyl‐1,3,5‐hexatriene (DPH) and 1,4‐diphenyl‐1,3‐butadiene (DPB) has been investigated. The rate of degradation has been monitored by following the change of the mechanical properties of the polymer during accelerated indoor aging tests. It was found that both additives are efficient sensitizers of the photodegradation of polyethylene. The mechanism of photo‐oxidation has been investigated by ESR and IR spectroscopy and it has been interpreted on the basis of a complex mechanism which includes excited singlet oxygen (1O2) and the products of photodegradation of the additives.Singlet oxygen, produced by DPB and DPH and/or by impurities present in the polymer, reacts with the additives themselves and, directly, with polyethylene. In turn, the products of photodegradation of the additives react with the polymer via hydrogen atom abstraction, further promoting the photodegradation.Irradiation carried out in absence of air seems to rule out the possibility of direct hydrogen atom abstraction by DPB and DPH.
Iodine‐initiated, solid‐state copolymerization of tetraoxane with 1,3‐dioxolane in the presence of methylal. I. Fundamental study on beaker‐scale copolymerization
Authors: Ishigaki Isao , Watanabe Yuhei , Morita Yosuke , Takada Kiyoshi , Ito Akihiko 
Published: April 2003

AbstractThe iodine‐initiated, solid‐state copolymerization of tetraoxane with 1,3‐dioxolane in the presence of methylal has been studied on a beaker scale. It was found that tetraoxane can be easily copolymerized with 1,3‐dioxolane by a small amount of iodine as initiator and gives oxymethylene copolymer with excellent thermal stability in a high yield. The copolymerization was largely influenced by the concentrations of iodine, 1,3‐dioxolane, and methylal, i.e., the polymerization rate increased with increase not only in iodine but also in 1,3‐dioxolane, and the thermal stability and the molecular weight of the copolymer were mainly affected by 1,3‐dioxolane and methylal concentration, respectively.
Diffusion of radioactively tagged penetrants through rubbery polymers. I. Penetrants with very low solubility
Authors: Rhee Chong‐Kon , Ferry John D. 
Published: April 2003

AbstractThe diffusion of radioactively tagged n‐hexadecane, 1,7‐heptanediol, and ethylene glycol has been studied in one polar and six nonpolar rubbery polymers. The penetrant–polymer pairs included some in which the two components were miscible in all proportions and some in which they were nearly incompatible (solubility of penetrant in polymer of the order of 1%). The theory for the thin smear method for measuring the diffusion coefficient was evaluated for incompatible pairs with two cases: case 2, when the rate‐limiting step is diffusion through the polymer; and case 3, when the rate‐limiting step is entry into the polymer across the penetrant–polymer interface. They are easily distinguished experimentally from each other and from case 1, which refers to completely miscible pairs. In examples of case 3, e.g., ethylene glycol with butadiene or styrene–butadiene rubbers, the half‐time for saturating the polymer surface in contact with the penetrant was found to be several days at 25°C. The diffusion coefficients, when compared in four hydrocarbon rubbers, of n‐hexadecane and 1,7‐heptanediol were similar in magnitude even though in each rubber the hexadecane was soluble in all proportions and the diol only very slightly. The diffusion coefficient of ethylene glycol, despite its extreme thermodynamic incompatibility, appeared to be somewhat larger than those of the other penetrants.
Radiation degradation of α‐substituted acrylate polymers and copolymers
Authors: Helbert John N. , Caplan Philip J. , Poindexter Edward H. 
Published: April 2003

AbstractRadiation degradation is observed in poly(methyl α‐chloroacrylate), poly(methyl α‐cyanoacrylate), and poly(α‐chloroacrylonitrile) homopolymers and their respective MMA copolymers when γ‐irradiated in vacuo. Polymer degradation susceptibilities are quantified in terms of G(scission radicals) and G(scission) − G(crosslinks), measured by EPR and membrane osmometry, respectively, values by these two methods are compared. Higher G(rads) values ranging from 2 to 6 and [G(s) − G(x)] values ranging from 2 to 11 are obtained for the substituted polymers and copolymers relative to the values for PMMA (1.6; 1.9), a standard e‐beam positive resist, which suggests that these modified polymers are more sensitive e‐beam resists than PMMA.
Accelerated photo‐oxidation of polyethylene. I. Screening of degradation‐sensitizing additives
Authors: Taylor Lynn J. , Tobias John W. 
Published: April 2003

AbstractNumerous simple compounds have been shown to be capable of accelerating the photo‐oxidation of polyethylene upon exposure to wavelengths near 300 nanometers. Probable mechanisms of photo‐initiation by the principal classes of degradation‐promoting additives are discussed.
Preparation and properties of phenolic resin laminates. I. Laboratory evaluation
Authors: Meier J. F. , Bellott E. M. , Frank P. P. 
Published: April 2003

AbstractThe preparation and properties of sodium carbonate and sodium hydroxide‐catalyzed phenolic resins polymerized in 1‐liter glass reactors over a broad range of F/P mole ratios are described. Laminates produced from selected sodium carbonate‐catalyzed resins coated on kraft paper are discussed and compared with laminates prepared from standard sodium hydroxide‐catalyzed resins. Several apparent advantages of the sodium carbonate‐catalyzed resin systems over the sodium hydroxide‐catalyzed resins are presented. The superior performance is attributed to the high degree of crosslinking resulting from the high concentration of methylolated phenols present in the sodium carbonate‐catalyzed resin.
A new method of determination of the permeability of vapors of volatile liquid substances through polymer membranes
Authors: Izydorczyk Jan , Podkówka Józef , Salwiński Janusz , Grzywna Zbigniew 
Published: April 2003

AbstractA new apparatus for the determination of vapor permeability of volatile liquid substances through polymer membranes has been described. The permeability of the vapor is calculated from the measurements of the depression rate of the liquid meniscus in a calibrated capillary tube. The conditions of the measurements by means of the described method are very close to those of the average and practical application of foils. The method is characterized by a simple design of the apparatus, easy handling, and simplicity of the determinations, so it may constitute the basis of vapor permeability determination standards. The results obtained by means of the described method were compared with those derived from the partition cell method.
Radiation yield of hydrogen chloride in gamma‐irradiated poly(vinyl chloride) stabilized by epoxy compounds
Authors: Lerke I. , Szymański W. 
Published: April 2003

AbstractThe GHCI values of γ‐irradiated PVC mixtures were studied after addition of various amounts of three epoxy stabilizers: diglycidyl ether of 2,2‐bis(4‐hydroxy‐3‐methylphenyl)propane (I); diglycidyl ether of 1,1‐bis(4‐hydroxyphenyl)cyclohexane (II), and butyl‐cis‐9,10‐epoxystearate (III). The results indicated that two processes are essential for the stabilization: HCI capture by the epoxy groups, and an external protective effect, due to the remaining part of the stabilizer molecule. The role of the benzene rings in stabilizers I and II, as compared with the protective effect due to the long chains of stabilizer III, is not as dominant as one would expect.
Dyeing of chemically modified celluloses. II. Effect of chemical modification of cellulose on the dyeing properties of some direct dyes
Authors: Hebeish A. , Moursi A. Z. , Khalil M. I. , Abdel‐Mohdy F. A. 
Published: April 2003

AbstractThe behavior of partially acetylated cellulose, partially carboxymethylated cellulose, cyanoethylated cellulose, and cellulose grafted with polyacrylontrile toward three direct dyes, namely, Chlorantine Fast Red 6 BLL, Solophenyl Orange T4RL, and Diphenyl Brilliant Flavine 7GFF, was studied. Partially acetylated cellulose having 2.06% combined acetic acid showed higher dye uptake than the unmodified cellulose. The amount of dye uptake increased as the acetyl content increased up to 4% combined acetic acid. Beyond this, enhancement in the dye uptake was not significant. Whereas partially carboxymethylated cellulose showed a lower dye uptake than the control. The dye uptake decreased considerably as the carboxymethyl groups increased. The same holds true for cyanoethylated cellulose where increasing the cyanoethyl content caused a substantial reduction in the dye uptake. On the other hand, cellulose grafted with polyacrylonitrile up to 18.3% graft yield showed much higher dye uptake than the ungrafted cellulose.
Determination of compositional heterogeneity in butadiene–styrene copolymers by density gradient ultracentrifugation
Authors: Stacy C. J. 
Published: April 2003

AbstractSedimentation equilibrium in a density gradient gives a sensitive intermolecular composition analysis of styrene–butadiene copolymers. This information is sometimes unobtainable by other analytical techniques. The density gradient is formed by action of the centrifugal field upon a carbon tetrachloride–cyclohexane mixture, and the equilibrium position of each polymeric solute in the gradient depends upon its effective buoyant density. The large difference in styrene and butadiene densities makes possible accurate composition calibrations which are independent of molecular weight and branching.
Preparative gel permeation chromatography. I. Polypropylene
Authors: Vaughan M. F. , Francis M. A. 
Published: April 2003

AbstractPreparative gel permeation chromatography was used to produce a number of polypropylene reference samples, within the molecular weight range of 10,000–600,000, from commercial materials. Some of these materials were degraded in a controlled manner to give base materials having suitable molecular weight characteristics. A procedure has been developed using a single preparative column packed with equal quantities of Styragel with nominal exclusion limits of 102, 103, 104, and 105 nm. The volume of solvent for recovery was minimized by use of higher loading factors than in analytical GPC (some 2–20 times more polymer was thus fractionated in each experiment). Under these conditions the fractions first eluted were sharpest having polydispersities of about 1.5. First fractions, from different base materials, were characterized by analytical GPC, and those of similar molecular weight and polydispersity were combined to give the reference samples. Refractionation was necessary with the highest molecular weight base material because the first stage fractions were not sharp enough. Some of these fractions were recovered at elution volumes where much lower molecular weight material was expected. Comparison with results from the other base materials indicates that the primary cause of the spreading is not overloading. This spreading is explained in terms of slower partitioning of the larger molecules between the interstitial fluid and the gel particles.
Stress–strain behavior, hardness, and thermomechanical properties of butadiene–styrene block copolymers as a function of processing technique
Authors: Leblanc Jean L. 
Published: April 2003

AbstractStress–strain properties of star‐shaped butadiene–styrene block copolymers were carried out on extruded sheet and injection molded samples. A striking “plastic‐like” behavior was observed during the first extension, with a marked yield point, a drawing process, and an important hysteresis. These phenomena disappeared on the second elongation, but annealing below the polystyrene glass transition temperature gave again the initial behavior. A marked processing technique dependence was observed in the stress–strain experiments. An important variation in hardness was observed before and after stretching, and annealing experiments permitted the study of hardness recovery. A logarithmic relation between recovered hardness and the annealing time at constant temperature was deduced from the experimental data. Thermomechanical analysis curves show singular transitions between 20° and 85°C, which disappear on stretching. An important discrepancy occurs in TMA curves of extruded and injected samples. A comparison is made of thermomechanical behavior of linear and star‐shaped SBS block copolymers. A modified model is proposed for a reversibly deformable structure composed of polybutadiene and polystyrene linked ends at the diffuse interfacial region between the PS domains and the PB matrix.
The effects of flow rate and column combination on the separation efficiency in multicolumn gel permeation chromatography
Authors: Ambler M. R. , Fetters L. J. , Kesten Y. 
Published: April 2003

AbstractUsing general‐purpose multicolumn sets, it was found that separations could be increased by increasing analysis time, either by decreasing flow rate or increasing column length. Several examples are shown illustrating the influence of these system variables. The generation of linear calibration curves over extended molecular weight ranges is discussed. In particular, the desirability of using high molecular weight standards to extend the calibration curve and eliminate extrapolation of the curve is shown. Not using all available gel porosities, i.e., gapped column sets, is shown to be detrimental to the resolution of molecular species. It was found that with the use of sufficiently long column lengths and flow rates, accurate molecular weights of both narrow and broad molecular weight distribution samples are directly calculable from the chromatogram without the need for peak spreading corrections.
Semiconductor properties of polyamide‐6 containing dispersed copper or zinc additives
Authors: Czekaj Tadeusz , Kapko Jerzy 
Published: April 2003

AbstractIt was expected that elemental copper or zinc introduced into polycaproamide would interact with amide groups of the polymer and that the materials would be characterized by semiconductor properties. To prove this theory, resistivity at several temperatures was determined and thermal activation energies calculated. As the metal contents were relatively low, metallic conductivity was avoided. Temperature‐resistivity dependence and a negative temperature coefficient of the resistivity prove that polyamide–metal compositions can be classified as semiconductors.
Polymerization of styrene with n‐butyllithium in a batch reactor. A mathematical model
Authors: Tanlak Tayfun , Ahmad Abu , Treybig Michael N. , Anthony Rayford G. 
Published: April 2003

AbstractSytrene was polymerized in a 0.8‐liter vessel which was operated as an isothermal and a nonisothermal batch reactor. Styrene and n‐butyllithium conversions were determined for different reaction times. Rate equations were developed by use of the isothermal data and then used to estimate the conversions for the nonisothermal experiments. The importance of using nonisothermal data in the development of rate equations is illustrated.
Reclamation of vulcanized rubbers by chemical degradation. VIII. Absorption of oxygen and degradation of cis‐1,4‐polyisoprene by phenylhydrazine–iron(II) chloride system
Authors: Yamashita Shinzo , Kato Shin'Ichi , Kawabata Nariyoshi , Okamoto Takao 
Published: April 2003

AbstractAbsorption of oxygen and degradation of cis‐1,4‐polyisoprene by the phenylhydrazine–iron(II) chloride system was investigated at 30°C in connection with the mechanism of reclamation of vulcanized rubbers by the system. In the presence of iron(II) chloride, phenylhydrazine rapidly absorbed an equimolar amount of oxygen and evolved an equimolar amount of nitrogen. Gas‐chromatographic analysis of the reaction mixture showed the presence of benzene, phenol, and biphenyl in 37%, 35–60%, and 4–8% yields, respectively, based on phenylhydrazine. When cis‐1,4‐polyisoprene was added to the reaction mixture, additional absorption of oxygen was observed. Molecular weight of the polymer decreased during the oxygen absorption, and the scission efficiency (i.e., number of mole scissions/mole oxygen) was 0.14–0.26.