bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental determination of the relationships among various measures of fluid elasticity
Authors: Stratton Robert A. , Butcher Allan F. 
Published: April 2003

AbstractThe viscoelastic properties of a 4% solution of monodisperse polystyrene (molecular weight 394,000) in Aroclor 1260 were determined by the following techniques: creep recovery, stress relaxation upon cessation of steady flow, dynamic measurements, and normal stress difference and shear stress measurements in steady flow. All measurements were carried out with cone and plate geometry in a Weissenberg rheogoniometer. The modification of this instrument to perform creep and creep recovery experiments by use of an air‐bearing suspension and an air‐turbine drive is described. A broad range of shear rates and frequencies encompassing both linear and nonlinear behavior was employed. The elastic behavior is described in terms of the recoverable shear strain s or the steady‐state compliance Je°. The first three techniques gave identical results for Je° in the range of linear viscoelasticity for which it is defined. The normal stress difference measurements confirmed Lodge's relation s = (P11 − P22)/2σ21. Reasons for previous experimental disagreement with this result are discussed.
Fold surface of polyethylene single crystals as assessed by selective degradation studies. III. Application of the improved techniques to single crystals
Authors: Keller A. , Martuscelli E. , Priest D. J. , Udagawa Y. 
Published: April 2003

AbstractPrevious studies on selective degradation of polyethylene single crystals with fuming nitric acid have been extended, both by using acid of lower concentration which gave better control over the degradation, and by resorting to ozone as an oxidizing agent which among others enabled the degradation temperature to be conveniently lowered. The molecular weight distribution was followed by gel‐permeation chromatography in the course of degradation. Complete consistency between these different methods has been established, modifying some of the previous conclusions reached by this method. The principal feature which emerges is that we have a distribution of fold lengths. The largest straight fold stems can stretch across nearly the entire layer defined by the low‐angle x‐ray period, while there is a continuous distribution of shorter folds terminating deeper down in the crystals. The limiting depth at which the number of terminating folds becomes negligible can be identified and quantitatively assessed. The method of analysis is described, and individual data are discussed in detail. This picture of a fold surface layer containing essentially adjacently reentrant folds of uneven length agrees with quite recent results on other related chain‐folded systems (annealed crystals, short chains, bulk structures) obtained in these laboratories and thus appears to be of general validity. The consequences of the model for our picture on polymer crystals in particular on the nature of the “amorphous” component, are discussed.
Time‐dependent heat capacity in the glass transition region
Authors: Wolpert Stephen M. , Weitz Alexander , Wunderlich Bernhard 
Published: April 2003

AbstractTime‐dependent, apparent heat capacities of glucose, poly(vinyl chloride), polystyrene, selenium, poly(methyl methacrylate), and poly(2,6‐dimethyl‐1,4‐phenylene ether) in the glass transition region were determined by differential thermal analysis. The thermal history was set by linear cooling at rates between 0.007 and 160°C/min. Linear heating for analysis was carried out at rates between 0.3 and 600°C/min. Average activation energies of 52, 81, 90, 54, 77, and 108 kcal/mole, respectively, were evaluated by using the hole theory of glasses previously developed. Within experimental limitations all data could be described quantitatively by the theoretical expressions using only one parameter, the number of frozen‐in holes, to described the thermal history. Experimental and theoretical limitations are discussed.
Structural evaluation of branched polyethylene by combined use of GPC and gradient‐elution fractionation
Authors: Wild L. , Ranganath R. , Ryle T. 
Published: April 2003

AbstractA method is described and a computer program outlined whereby gel‐permeation chromatographic analysis of fractions from gradient‐elution fractionation of branched polyethylenes provides a complete molecular weight evaluation of each fraction and the parent resin. The procedure involves the use of the universal calibration concept of Benoit et al. in a way that eliminates the ambiguities present in attempts to apply it directly to whole polymers. The resultant molecular weight data for fractions, when related to their solution viscosity and low‐shear melt viscosity and to their infrared analysis, provides a total structural evaluation of a branched polyethylene resin, including molecular weight molecular weight distribution and the distribution of both long‐and short‐chain branching. The potential of this method for providing a comprehensive structural evaluation of branched polyethylene is illustrated by examples of its application in the analysis of some commercial resins.
Copolymerization of tetrahydrofuran with propylene oxide. III. 1,2,3‐propanetriol as cocatalyst
Authors: Blanchard L. P. , Kondo S. , Moinard J. , Pierson J. F. , Tahiani F. 
Published: April 2003

AbstractThe cationic copolymerization of tetrahydrofuran with propylene oxide was investigated with the use of boron trifluoride etherate, 1,2,3‐propanetriol, and ethylene chloride as catalyst, cocatalyst, and solvent, respectively. The reactions were carried out in the liquid phase under a blanket of dry nitrogen at atmospheric pressure and in the temperature range from −10° to +20°C. Comonomer consumption was followed by vapor‐phase chromatography, while the products were analyzed by gel‐permeation chromatography, nuclear magnetic resonance, vapor‐pressure osmometry, and chemical endgroup analysis (phthalation). The investigation was directed towards the elucidation of the influence of the initial cocatalyst content, the initial mole fraction of the comonomer, and the temperature of reaction, on the kinetics of the reaction (rates of disappearance of comonomers, reactivity ratios, comonomer conversions and product yields) and on the characteristics of the products formed (composition, molecular weight, and primary and secondary hydroxyl content). An attempt is made to interpret the results reported in the paper.
Grafting of acrylic acid onto radiation‐peroxidized polypropylene film in the presence of ferrous ion
Authors: O'Neill Thomas 
Published: April 2003

AbstractAcrylic acid has been grafted from aqueous solution onto 70 μ isotactic polypropylene‐film previously peroxidized by irradiating in air with both 400 keV electrons and γ‐radiation from a 60Co source. Ferrous ion has been used to induce the redox decomposition of the macromolecular peroxy species at temperatures between 0 and 40°C. It has been shown that the effect of low [Fe2+] is to increase grafting rates, but that at [Fe2+] > 8 × 10−4 molal the retarding effect of the reducing ion becomes increasingly important. At constant [Fe2+] a pronounced maximum in rate is observed at around 50 wt‐% of acrylic acid; this may be related to increased swelling of the polymer matrix at this point. The initial rate of grafting increases as the square root of the preirradiation dose and, in the preirradiation dose rate range, 1.6–8.0 Mrad/sec, is independent of the dose rate. The grafting rate during the later stages of the reaction, however, increases as the preirradiation dose rate decreases. In the temperature range 0–40°C, the overall activation energy is 19 kcal/mole; from this value, the activation energy of initiation has been estimated to be around 20 kcal/mole.
Preparation and polymerization of someN‐(dialkylaminoalkyl)acrylamides
Authors: Hoke Donald I. , Surbey Donald L. , Oviatt William R. 
Published: April 2003

AbstractA series ofN‐(dialkylaminoalkyl)acrylamides was synthesized by reductive amination ofN‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide (diacetone acrylamide) and by the reaction of either an alkenylamine or an amino alcohol with acrylonitrile. These monomers homopolymerize and copolymerize readily to form high molecular weight products. The solubility of the monomers and their homopolymers in water ranges from soluble to insoluble at room temperature. The insoluble materials can be quaternized readily to produce water‐soluble products. The solubility of the homopolymers in water decreases with increasing temperature. Glass transition and decomposition temperatures of the homopolymers are reported.
Magnetic circular dichroism studies of polystyrene solutions
Authors: Kaye H. , Hwang J. S. 
Published: April 2003

AbstractThe magnetic circular dichroism (MCD) spectra of “atactic” and isotactic polystyrene solutions have been found to be sensitive to configurational and conformational differences. The ratio of B terms for “atactic” polystyrene (predominantly syndiotactic) to that of cumene was found to pass through a minimum as the coil expanded in various solvents. The ratio of dipole strengths D also passed through a minimum. For isotactic polystyrene and cumene the ratio of B terms increased with increasing coil size in the range of solvents utilized. The ratio of B terms of isotactic polystyrene over atactic polystyrene was found to go through a maximum as the coil expanded whereas the ratio of dipole strengths was found to continuously decrease. These results have been interpreted on the basis of the change in short range and long range orientation and interaction distances between chromophores during coil expansion. It is concluded that the microscopic conformation of isotactic and atactic polystyrene are very different in very good solvents. The B/D ratio for cumene was found generally to decrease with increasing solvent power.
Telechelic diene prepolymers. III. Polymerization temperature study of polybutadienes
Authors: Reed Samuel F. 
Published: April 2003

AbstractA study of the effect of the polymerization temperature on the yield and properties of hydroxyl‐ and carboxyl‐terminated polybutadiene prepolymers has been made. Polymerization reactions were conducted in dioxane with 4,4′‐azobis(4‐cyano‐n‐pentanol) and 4,4′‐azobis(4‐cyanovaleric acid) as the free‐radical initiators. The most significant result obtained was the observation that the polymerization temperature exhibited a pronounced effect on the heterogeneity index of the prepolymers.
Alternating copolymer of butadiene and propylene. III
Authors: Furukawa Junji , Amano Hirotoshi , Hirai Ryuichi 
Published: April 2003

AbstractAlternating copolymerizations of butadiene with propylene and other olefins were investigated by using VO(acac)2–Et3Al–Et2AlCl system as catalyst. Butadiene–propylene copolymer with high degree of alternation was prepared with a monomer feed ratio (propylene/butadiene) of 4. Alternating copolymers of butadiene and other terminal olefins such as butene‐1, pentene‐1, dodecene‐1, and octadiene‐1,7 were also obtained. However, the butadiene–butene‐2 copolymerization did not yield an alternating copolymer but a trans‐1,4‐polybutadiene.
High‐resolution NMR spectra of the polysulfones of six monolefins
Authors: Ivin K. J. , Navrátil M. , Walker N. A. 
Published: April 2003

Abstract100‐MHz NMR spectra are reported for solutions of the 1:1 copolymers of sulfur dioxide with hex‐1‐ene, cis‐ and trans‐but‐2‐enes, cyclohexene, cyclopentene, and norbornene, including the deuterated polymers made from hex‐1‐ene‐2‐d1, cis‐ and trans‐but‐2‐ene‐2,3‐d2, and cyclohexene‐3,3,6,6‐d4. The resolution of the spectrum of poly‐(hex‐1‐ene sulfone) was very poor in CCl4 as solvent but good in polar solvents. The main‐chain CH2 protons are nonequivalent, and their chemical shifts show sensitivity to dyad structure; the α‐CH2 protons are also non‐equivalent. The spectra of most of the other polymers are discussed in terms of possible preferential modes of addition as well as tacticity effects.
Determination of molecular weight distribution for polypropylene by column fractionation and gel‐permeation chromatography
Authors: Ogawa Toshio , Suzuki Yoshitake , Inaba Tadami 
Published: April 2003

AbstractInvestigations on the molecular weight distribution of cyrstalline polypropylene were carried out by column fractionation and gel‐permeation chromatography for the purpose of comparing the determination methods. Average molecular weight, standard deviation, skewness, and kurtosis were calculated as statistical parameters from the distribution curve of each, and the number‐average and weight‐average molecular weights were determined by osmometry and light scattering. The molecular weight distribution curves obtained from column fractionation were found to be narrower than those from gel‐permeation chromatography, and it was confirmed that the molecular weight distribution curve obtained from GPC was more accurate and reliable than that from column fractionation by the fact that the average molecular weight from GPC agreed fairly well with that from the absolute methods. On the other hand, no clear difference between these determination methods was observed with respect to skewness and kurtosis of the data, while the standard deviation from GPC seemed to be greater than that from column fractionation.
Effect of amines on the ceric ion‐initiated polymerization of vinyl monomers. II. Polymerization of acrylonitrile by ceric ion in presence of various substituted amines
Authors: Saha Sisir K. , Chaudhuri Ajit K. 
Published: April 2003

AbstractThe effect of various substituted amines on the polymerization of acrylonitrile initiated by ceric ammonium sulfate has been studied in aqueous solution at 30°C. It was found that the secondary and tertiary amines considerably increased the rate of polymerization, whereas the primary amines seemed to have no effect at all. From the kinetic studies it was found that the overall polymerization rate Rp is independent of ceric ion concentration and can be expressed by the equation: Rp = k1 [amine] [monomer] + k2[monomer]2, where k1 and k2 are constants (involving different rate constants). The accelerating effect of the amines was attributed to a redox reaction between the ceric ion and the amine involving a single electron transfer, the relative activity of the different amines being thus dependent on the relative electron‐donating tendency of the substituents present in the amine. The mechanism of the polymerization is discussed on the basis of these results, and various kinetic constants are evaluated.
Observation of pentads in deuterated polyacrylonitrile by NMR spectroscopy
Authors: Matsuzaki Kei , Okada Muneshisa , Goto Kojitsu 
Published: April 2003

AbstractThe deuterium‐decoupled methine proton spectra of polyacrylonitrile‐β,β‐d2 were measured at 156°C in dimethylsulfoxide‐d6 solution. Splittings of triad peaks caused by pentad sequences were observed. The isotactic triad resonance was resolved into three peaks and the heterotactic resonance into two peaks, while the syndiotactic resonance was unresolved or resolved into three peaks. The splittings were assigned by comparing the probability of each pentad sequence with observed intensities. The pentad signal shifted to the higher magnetic field with increasing number of meso configurations as neighbors of the central triad. It was observed that the pentad of atactic polyacrylonitrile‐β,β‐d2 obeyed Bernoullian statistics but that of isotactic polymer obtained by γ‐ray irradiation of the canal complex seemingly obeyed first‐order Markov statistics.
Ability of poly(vinyl alcohol) fibers to initiate graft copolymerization
Authors: Ogiwara Yoshitaka , Igeta Kikuji , Kubota Hitoshi 
Published: April 2003

AbstractIt was noted in a graft copolymerization reaction involving a system of poly(vinyl alcohol) fibers (PVA fibers), methyl methacrylate, and water that fibers oxidized with hydrogen peroxide or sodium hypochlorite or ferric ion‐adsorbing fibers effectively initiate the reaction as in the case of cellulose fibers. The initiation reaction of the sample was markedly activated by the presence of a pretreatment with an oxidizing agent at a concentration on the order of 10−9 mole/l., but the oxidized samples were sharply deactivated by such means as reduction and oximation. Since model initiators for the present system, such as iron(III) acetylacetonate‐adsorbing PVA fibers or ferric ion‐adsorbing fibres, with the co‐existence of acetylacetone were observed to initiate graft copolymerization effectively, it is believed that carbonyl groups in modified PVA fibers could be a major factor for initiating copolymerization through interaction with metallic ions.
Study of (π‐C5H5)2Ti(C2H5)Cl and its higher homologs in soluble Ziegler catalysts
Authors: Waters J. A. , Mortimer George A. 
Published: April 2003

AbstractSoluble ethylene polymerization catalysts derived from (π‐C5H5)2Ti(R)Cl and R′AlCl2 where R is ethyl or higher alkyl and R′ may be methyl or ethyl, were studied both by polymerization kinetics at 0°C and by diagnostic experiments. An early acceleration in rate occurred at this temperature in toluene solvent which was due to a solvent dependent increase in catalyst activity, not to a gradual formation of catalyst. No such solvent effect was found in nonaromatic solvents. The subsequent decay in rate, at least at low temperatures, did not depend upon valence reduction. The effect of Al/Ti ratio was studied, and certain discrepancies in the literature were shown to be due to the method of making kinetic measurements. Oxygen, which has previously been reported to affect the polymerization rate with these catalysts, was also found to eliminate the acceleration period in toluene when present in the amount of 1% of the catalyst. These catalysts gave polymers at low temperature for which the active site had long life and which did not undergo chain transfer. Therefore, they approximate many of the characteristics of living polymers.
Polymerization of vinyl chloride and copolymerization with propylene by a ternary catalyst system
Authors: Akimoto Akira , Yoshida Toshirō 
Published: April 2003

AbstractPolymerization of vinyl chloride by the ternary catalyst system of VOCl3–AIRnCl3–n complexing agent was investigated. It was suggested that the formation of a polar complex (or charge‐transfer complex) between AlRnCl3–n and the complexing agent participated in the polymerization of vinyl chloride. In the copolymerization of vinyl chloride with propylene with the present catalyst system, it was more difficult to incorporate the propylene unit in the copolymer than with a typical radical catalyst.
Carbon‐13 NMR of polybutadiene
Authors: Mochel V. D. 
Published: April 2003

AbstractBy using the carbon‐13 NMR technique, it is shown that there are no cis‐1,4–trans‐1,4 linkages in a n‐BuLi‐catalyzed polybutadiene. The polymer consists of “blocks” of cis‐1,4 units and trans‐1,4 units separated by isolated vinyl units. Preliminary evidence suggests this might also be true for other types of 1,3‐diene polymerization. Some of the implications of this finding on the mechanism of polymerization are discussed. Tacticity triad distributions are readily determined in polybutadienes with high 1,2 addition contents.
Radiation‐induced grafting of styrene vapor to polyethylene
Authors: Kamel Ihab , Machi Sueo , Silverman Joseph 
Published: April 2003

AbstractThe radiation‐induced grafting of styrene vapor to low‐density polyethylene film of 0.063 mm thickness was studied at 23°C at a dose rate of 1.98 × 104 rad/hr. The concentration C of monomer in the film was measured as a function of pre‐irradiation exposure time to monomer vapor. The concentration‐dependent diffusion coefficient of styrene in polyethylene was calculated to be 4.9 × 10−9 exp {2.0C/C0} cm2/sec, where C0 is the saturation concentration of styrene in the film, and a linear boundary diffusion coefficient for styrene vapor into polyethylene film was found to be 2.0 × 10−7 cm/sec. The rate of grafting was determined as a function of the concentration of styrene absorbed in the film. The maximum graft yield was obtained with an initial styrene concentration in the film of 4 wt‐%. Under conditions of low initial monomer concentration, the grafting rate increases with irradiation time. The results are compared with previously published data on grafting of polyethylene from methanol–styrene solutions. They are explained in terms of the viscosity of the amorphous region as a function of styrene content and the resistance to the diffusion of monomer at the film–vapor interface.
Vinyl polymerization by metal complexes. III. Vinyl polymerization initiated by oligoamide and cupric ion system
Authors: Takemoto K. , Takata T. , Inaki Y. 
Published: April 2003

AbstractPolymerization of methyl methacrylate and other vinyl monomers was studied in the presence of oligoamide (ϵ‐aminocaproic acid, its dimer, trimer, tetramer, and pentamer) and cupric ion in aqueous media. The polymerization was found to be of free‐radical character and selective for the type of vinyl monomer. Carbon tetrachloride can accelerate the polymerization. The initiation mechanism of the polymerization is discussed. Spectroscopic measurements were indicative of formation of 1:1 complex between oligoamides and cupric ion in aqueous NaClO4 solution. Some chemical and physical properties of the resulting polymers were measured.
Mechanism of thermal degradation of poly(vinyl chloride)
Authors: Bataille P. , Van B. T. 
Published: April 2003

AbstractThe mechanism of thermal degradation of poly(vinyl chloride) has been studied by pyrolysis up to 400°C in a thermobalance under four kinds of dynamic atmospheres: helium, oxygen, air, and hydrogen chloride. The gaseous product from the thermobalance was analyzed for hydrogen chloride by the argentometric determination of chloride ions by using Mohr's method. An attempt was made to analyze for other gases in the product stream by chromatography with the use of a glass column, but failed due to the accumulation irreversibly of hydrogen chloride on the column. The molecular weights of the samples were determined by measurements of viscosities at 25°C in cyclohexanone; their molecular weight distributions were studied by fractionation and gelpermeation chromatography (GPC). From the thermograms, the mechanism of degradation in different heating atmospheres, the rate, the heat effect, the energy of activation, and the order of decomposition were deduced.
Polymerization by amine–metalloid fluoride salts. I. Polymerization of ethyl vinyl ether by anilinium hexafluoroantimonate
Authors: Harris James J. , Temin Samuel C. 
Published: April 2003

AbstractAnilinium hexafluoroantimonate is shown to be a very efficient cationic initiator for the polymerization of ethyl vinyl ether from −78°C to 25°C. The polymer molecular weight varied with temperature and solvent and ranged from very low to near 200,000. After a threshold concentration of catalyst had been obtained, yields were semiquantitative. The catalyst requirement was quite low, near quantitative yields being obtained at concentrations as low as 10−3 mole‐%. Polymer obtained in heptane had a small degree of isotacticity.
Solid‐state photopolymerization of α,α′‐bis(4‐acetoxy‐3‐methoxybenzylidene)‐p‐benzenediacetonitrile
Authors: Holm Myron J. , Zienty Ferdinand B. 
Published: April 2003

AbstractOne crystalline form of α,α′‐bis(4‐acetoxy‐3‐methoxybenzylidene)‐p‐benzenediacetonitrile is photopolymerized by a four‐center reaction to give a polymer containing alternating benzene and cyclobutane rings. The polymer is highly crystalline and insoluble in most solvents. Location of groups around the cyclobutane ring is deduced from the products obtained on thermal decomposition. Chain contained benzene rings are located in positions 1 and 3; aromatic groups alternate sides of the cyclobutane ring. Special characterization and quantum yield of the polymerization are reported, as well as polymer solution viscosity and alkaline depolymerization of the polymer.