bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of long‐chain branching on the relation between steady‐flow and dynamic viscosity of polyethylene melts
Authors: Shroff Ramesh N. , Shida Mitsuzo 
Published: April 2003

AbstractThe steady‐state viscosity η, the dynamic viscosity η′, and the storage modulus G′ of several high‐density and low‐density polyethylene melts were investigated by using the Instron rheometer and the Weissenberg rheogoniometer. The theoretical relation between the two viscosities as proposed earlier is:\documentclass{article}\pagestyle{empty}\begin{document}$ \eta \left( {\dot \gamma } \right){\rm } = {\rm }\int {H\left( {\ln {\rm }\tau } \right)} {\rm }h\left( \theta \right)g\left( \theta \right)^{{\raise0.7ex\hbox{$3$} \!\mathord{\left/ {\vphantom {3 2}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{$2$}}} \tau {\rm }d{\rm }\ln {\rm }\tau $\end{document}, where \documentclass{article}\pagestyle{empty}\begin{document}$ \theta {\rm } = {\rm }{{\dot \gamma \tau } \mathord{\left/ {\vphantom {{\dot \gamma \tau } 2}} \right. \kern-\nulldelimiterspace} 2} $\end{document}; \documentclass{article}\pagestyle{empty}\begin{document}$ {\dot \gamma } $\end{document} is the shear rate, H is the relaxation spectrum, τ is the relaxation time, \documentclass{article}\pagestyle{empty}\begin{document}$ g\left( \theta \right){\rm } = {\rm }\left( {{2 \mathord{\left/ {\vphantom {2 \pi }} \right. \kern-\nulldelimiterspace} \pi }} \right)\left[ {\cot ^{ - 1} \theta {\rm } + {\rm }{\theta \mathord{\left/ {\vphantom {\theta {\left( {1 + \theta ^2 } \right)}}} \right. \kern-\nulldelimiterspace} {\left( {1 + \theta ^2 } \right)}}} \right] $\end{document}, and \documentclass{article}\pagestyle{empty}\begin{document}$ h\left( \theta \right){\rm } = {\rm }\left( {{2 \mathord{\left/ {\vphantom {2 \pi }} \right. \kern-\nulldelimiterspace} \pi }} \right)\left[ {\cot ^{ - 1} \theta {\rm } + {\rm }{{\theta \left( {1{\rm } - {\rm }\theta ^2 } \right)} \mathord{\left/ {\vphantom {{\theta \left( {1{\rm } - {\rm }\theta ^2 } \right)} {\left( {1{\rm } + {\rm }\theta ^2 } \right)^2 }}} \right. \kern-\nulldelimiterspace} {\left( {1{\rm } + {\rm }\theta ^2 } \right)^2 }}} \right] $\end{document}. Good agreement between the experimental and calculated values was obtained, without any coordinate shift, for high‐density polyethylenes as well as for a low density sample with low nw, the weight‐average number of branch points per molecule. The correlation, however, was poor with low‐density samples with large values of the long‐chain branching index nw. This lack of coordination can be related to nw. The empirical relation of Cox and Merz failed in a similar way.
Fatigue as monitored by the torsion pendulum
Authors: Schrager M. 
Published: April 2003

AbstractThis paper describes the use of a new air‐bearing torsion pendulum as a nondestructive monitor of torsional fatigue in epoxy resin castings. Results indicate that both G′ and tan δ undergo significant changes as fatigue is induced in the specimen. In those specimens that have not been sufficiently post‐cured, cyclic fatiguing induces further crosslinking. However, this is accompanied by a competing reaction of crack formation and propagation leading ultimately to failure.
A theory of die‐swell
Authors: Tanner R. I. 
Published: April 2003

AbstractAn elastic‐fluid theory of die‐swell for long dies is presented. The theory predicts a swelling ratio De/d asymptotically proportional, for large values of swelling, to the cube root of the recoverable shear evaluated at the die wall. Here the recoverable shear is defined to be half the ratio (first normal stress difference/shear stress). Excellent agreement is shown between predicted De/d and measured De/d for experiments on melts and solutions for which adequate data are available.
Numerical solutions of the lamm equation. VI. Effects of hydrostatic pressure on velocity sedimentation of two‐component systems
Authors: Dishon Menachem , Weiss George H. , Yphantis David A. 
Published: April 2003

AbstractWe present the results of accurate numerical solutions to the Lamm equation, including the effects of hydrostatic pressure, in order to check methods for the estimation of parameters based on a diffusionless theory. Some estimates of boundary spreading due to diffusion are given. The results indicate that parameter estimates based on the position of the maximum concentration gradient lead to fairly accurate results.
NMR spectrum of poly(propene sulfide)
Authors: Ivin K. J. , Navrátil M. 
Published: April 2003

AbstractThe 100 MHz spectra of polymers of propene sulfide and propene‐2‐d1 sulfide have been determined in CDCl3, CCl4, and C6D6. In the deuterated polymer the main‐chain protons give rise to two overlapping AB quartets in which the two pairs of upfield B lines are coincident and the two pairs of downfield A lines are resolved. With CdCO3 as polymerization catalyst the downfield quartet is twice as strong as the upfield quartet. The former is ascribed to an isotactic dyad:
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and the latter to a syndiotactic dyad:
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Other catalysts (ZnCO3, CuCO3, SiO2/Al2O3, Na) produce an essentially atactic structure. The values τA = 7.125, τA′ = 7.155, τB = 7.45, JAB = −12.9 Hz, derived from the spectrum of the deuterated polymer (in CCl4) were used to obtain the following values from the spectrum of the undeuterated polymer (tertiary proton = Hc): τC = 7.131, JBC = 10.0 Hz, JCA = 4.1 Hz. The magnitudes of the vicinal coupling constants indicate a preferred trans conformation for the mainchain CC bond. τA, τB, and τC are somewhat dependent on solvent; τCH3 = 8.63, independent of solvent, and JCH3, HC = 6.2 Hz.
Mechanochemische aufpfropfung von polymeren an der oberfläche von füllstoffen als methode ihrer aktivierung
Authors: Taubman A. B. , Yanova L. P. , Blyskosh G. S. 
Published: April 2003

AbstractPeculiarities in the process of the mechanochemical grafting of polystyrene on freshly formed surface of particles of calcium carbonate on grinding in styrene were studied. It was established that the formation of homopolymer in this process is the result of rupture of individual chains of macromolecules, which are bound to the surface. If a small quantity of water is present in the monomer, the grafting is enhanced, due to an increase of the specific surface of the powder as a result of the reduction of its durability due to adsorption (Rehbinder effect). The grafting of polystyrene makes the solid surface hydrophobic and increases the activity of calcium carbonate as a filler for rubber.
Effects of nonionic surfactants on seeded polymerizations
Authors: Napper D. H. , Netschey A. , Alexander A. E. 
Published: April 2003

AbstractThe rate of polymerization of vinyl acetate in systems containing poly(vinyl acetate) seed particles was investigated. A significant reduction in rate was observed when nonionic surfactants were adsorbed onto the particles prior to polymerization. The molecular weight of the poly(ethylene oxide) moieties in the surfactants was varied over two decades. The diminution in rate was relatively insensitive to this molecular weight variation, at least for higher molecular weights (≥20,000). A minimum in the rate was apparent at lower molecular weights. No new nucleation was detectable in any of these systems. The results have been interpreted in terms of two properties of the dissolved poly(ethylene oxide) layers through which the oligomeric free radicals must diffuse in order to reach the major loci of polymerization inside the particles. These two properties, the effective thickness of the dissolved poly(ethylene oxide) layer and its average microscopic viscosity, are expected theoretically to be approximately self‐compensating when the molecular weight is varied.
Monomer reactivity ratios in graft copolymerization
Authors: Odian George , Kruse Robert L. , Kho Jose H. T. 
Published: April 2003

AbstractThis paper discusses monomer reactivity ratios in various radiation‐ and redox‐initiated graft copolymerizations. The polymers studied were polyethylene, cellulose acetate, poly(vinyl chloride), polytetrafluoroethylene, poly(vinyl alcohol), and poly(methyl methacrylate); the comonomer mixtures were styrene–acrylonitrile, methyl acrylate–styrene, acrylonitrile–methyl acrylate, and vinyl acetate–acrylonitrile. The polymer–comonomer mixture systems were so chosen as to permit study of both homogeneous and heterogeneous systems. The homogeneous systems included systems of low and high viscosity. The heterogeneous systems included both polymers swollen by the comonomer mixture and polymers not swollen by the comonomer mixture. None of the homogeneous grafting systems studied showed deviations from the normal copolymerization behavior under a variety of experimental conditions. Monomer reactivity ratios in graft copolymerization were the same as the values in nongraft copolymerization. The heterogeneous systems in which the polymer was swollen by the comonomer mixture yielded grafted copolymer compositions which were the same as those in nongraft copolymerization. The heterogeneous grafting system polytetrafluoroethylene/styrene–acrylonitrile showed deviations from normal copolymerization behavior at low degrees of grafting when the reaction was only on the polymer surface. The behavior became normal at higher degrees of grafting when the system approaches that in which the polymer is swollen by the comonomers. In all reaction systems, it was found that the use of radiation to initiate the reaction does not in any way affect the copolymerization behavior of the two monomers in a comonomer pair.
Metallation of unsaturated polymers and formation of graft copolymers
Authors: Tate D. P. , Halasa A. F. , Webb F. J. , Koch R. W. , Oberster A. E. 
Published: April 2003

AbstractThe use of N,N,N′,N′‐tetramethylethylenediamine (TMEDA) is known to enhance the metallation of capability of butyllithium. It has been found that this TMEDA–BuLi reagent smoothly metallates olefins in high yields at 50°C in less than 4 hr by replacement of allylic hydrogen. This reaction has been applied to unsaturated polymers such as polybutadiene and polyisoprene. The resulting products have lithium atoms scattered along the chain. The amount of lithium on the chain can be varied over wide limits. Each lithium atom on the chain can act as a site for grafting or adding functional groups to the base polymer. Thus, this method allows the preparation of polymers having controlled amounts of branching as well as the introduction of functional groups into the polymer. Through the use of this metallation technique, polymers containing styrene and butadience grafts are specifically reported. In addition, polymers containing hydroxyl or carboxyl groups along the backbone are prepared by using this technique.
Steady‐state kinetics during initial stages of radical bulk polymerization of acrylonitrile
Authors: Amdur S. 
Published: April 2003

AbstractThe bulk polymerization of acrylonitrile with azobisisobutyronitrile as initiator and FeCl3 as terminator was studied at 60°C. It was found that the reaction proceeds like solution polymerization and does not exhibit the familiar autoacceleration found in bulk polymerizations. It was concluded that a steady‐state condition of growing radical chains exists. Initial rates, to approximately 3% conversion, were measured dilatometrically and were found to be proportional to the ratio of the initiator to terminator concentration, where this ratio is smaller than 3 : 1 and are due to the predominance of the FeCl3 monoradical termination mechanism. On increasing the ratio of initiator to FeCl3, the usual biradical termination mechanism becomes important as well. Assuming that the ratio of propagation constant to termination constant in this work is similar to the knwon ratio in DMF solution, a monomer “effective” concentration in the bulk of about 20% of the nominal concentration of pure acrylonitrile (14.38 mole/l. at 60°C) can be calculated. This result is interpreted by a molecular mechanism for the bulk polymerization of acrylonitrile.
Oligomeric silazanes
Authors: Breed L. W. , Elliot R. L. 
Published: April 2003

AbstractHigh conversions of oligomeric silazanes that are not volatile at 200°C/0.1 mm are obtained when hexamethylcyclotrisilazane or octamethylcyclotetrasilazane is heated with a molar deficiency of dichlorodimethylsilane at 175°C. The oligomers, which show moderate solvolytic stability, contain disilazane, trisilylamine, and cyclodisilazane units. They are structurally similar to materials that have been prepared by others from hexamethylcyclotrisilazane and ammonium bromide. When the oligomers are treated with ammonia and heated to 325°C, evidence can be found in their spectra for the presence of oligocyclodisilazane structures.
α–γ transition in nylon 6
Authors: Abu‐Isa Ismat 
Published: April 2003

AbstractThe α to γ transition that occurs in nylon 6 upon iodine treatment was investigated by infrared spectroscopy, differential thermal analysis, and x‐ray diffraction techniques. Thin films of nylon (0.2 mil) were treated in either iodine–potassium iodide aqueous solution or in iodine vapor. Very short treatment times, in the order of 30 sec, were found to effect the transition when a solution 0.5M with respect to iodine was used. The infrared spectra of the iodine nylon complexes formed from either the α‐ or γ‐nylon 6 treated in vapor or dissolved iodine were all similar. This is an indication that molecular iodine is the active species in forming the complex. The temperature of the washing solution used to remove the iodine from the nylon determines whether an α‐nylon 6 or γ‐nylon 6 is obtained from the complex after washing. Nylon 6 plaque surfaces and thin films are similar in their behavior towards the iodine treatment. The γ‐nylon 6 is a stable modification at all temperatures below its melting point. The conversion of the γ form back to the α modification can occur only if the hydrogen bonding is severely affected, e.g., by phenol treatment, iodine treatment, melting, etc. Infrared spectroscopy provided no evidence for an α–γ transition in nylon 6 on heating the sample continuously through its melting point. The shapes of the melting peaks in the above two modifications of nylon 6 were sufficiently different to provide a means of identifying the two crystalline forms.
Irradiation‐grafted polymeric films. I. Preparation and properties of acrylic acid–grafted polyethylene films
Authors: Hamil H. F. , Adams L. M. , Harlowe W. W. , Martin E. C. 
Published: April 2003

AbstractGraft copolymers of low‐density polyethylene film and acrylic acid have been prepared by the direct grafting technique. The properties of 27.4, 33.9, 41.2, and 46.4 wt‐% poly(acrylic acid) graft copolymer films have been compared. Measurements include degree and uniformity of grafting, gel water content, degree of swelling on wetting, tensile strength, elongation, ion‐exchange capacity, water‐vapor transmission, and water flux and solute rejection under reverse osmosis conditions. These properties were found to vary as the composition of the graft copolymer changed; most properties were found to be a linear function of the degree of grafting.
Hydrogen‐transfer polymerization of cis‐ and trans‐crotonamides
Authors: Kobuke Yoshiaki , Hanji Katsumi , Furukawa Junji , Fueno Takayuki 
Published: April 2003

Abstractcis‐ and trans‐Crotonamides were polymerized in the presence of sodium tert‐butoxide in pyridine. It was found that both monomers undergo concurrent geometrical isomerization as well as polymerization. Polymers resulting from these isomeric monomers had identical microstructures. The rates of both polymerization and isomerization were evaluated from kinetic measurements. Kinetic investigations have also shown that the specific first‐order rate coefficient was independent of the isomer compositions and was identical for cis and trans monomers. The activation enthalpy was evaluated to be 15.0 kcal/mole.
Thermoplastic elastomers via radical polymerization. II
Authors: Zaganiaris Emmanuel J. 
Published: April 2003

AbstractSimple models are used to study the formation of thermoplastic elastomers using a method for preparation of block copolymers introduced by Tobolsky and Rembaum. It was found that a small excess of isocyanate groups produce branched block copolymers with significantly reduced fractions of AB and B type molecules.
Polymerization studies on 1‐ferrocenyl‐1,3‐butadiene
Authors: Van Landuyt Dennis C. , Reed Samuel F. 
Published: April 2003

AbstractThe polymerization behavior of 1‐ferrocenyl‐1,3‐butadiene has been investigated by using both free‐radical and anionic initiation techniques. Polymerization occurred readily under the promoting action of butyllithium; however, no polymerization occurred when azobisisobutyronitrile (AIBN) or benzoyl peroxide was employed as initiator. Copolymerizations were carried out with methyl methacrylate and styrene. The behavior of 1‐ferrocenyl‐1,3‐butadiene in the copolymerizations was followed by dilatometric rate measurements, solution viscosity determinations, and elemental analysis. The major effect observed was a severe reduction in the intrinsic viscosities of the copolymers. An explanation for the observed behavior of 1‐ferrocenyl‐1,3‐butadiene in these reactions is advanced.
Application of gel‐permeation chromatography to studies of the functionality distribution of carboxy‐ and hydroxy‐polybutadienes
Authors: Law Ronald D. 
Published: April 2003

AbstractSeparations of carboxy‐polybutadienes and hydroxy‐polybutadienes according to functionality have been effected using stepwise elution from silica gel. Recoveries in the 95–100% range have been achieved. Subjection of the fractions obtained from the silica gel separation to analysis via gel‐permeation chromatography and infrared or near‐infrared spectroscopy yields not only functionality distribution data, but also provides the relationship between molecular weight distribution and functional type. Analytical techniques and interpretation of data are discussed.
Free‐radical homopolymerization and copolymerization of vinylferrocene
Authors: Lai John C. , Rounsfell Thane , Pittman Charles U. 
Published: April 2003

AbstractThe benzene solution homopolymerization of vinylferrocene, initiated by azobisisobutyronitrile, gave a series of benzene‐soluble homopolymers. Thus, free‐radical copolymerization studies were performed with styrene, methyl acrylate, methyl methacrylate, acrylonitrile, vinyl acetate, and isoprene in benzene. With the exception of vinyl acetate and isoprene, which did not give copolymers with vinylferrocene under these conditions, smooth production of copolymers occurred. The relative reactivity ratios, r1 and r2, were obtained for vinylferrocene–styrene copolymerizations by using the curve‐fitting method for the differential form of the copolymer equation, by the Fineman‐Ross technique, and by computer fitting of the integrated form of the copolymer equations applied to higher conversion copolymerizations. In styrene (M2) copolymerizations, the curve‐fitting and Fineman‐Ross methods both gave r1 = 0.08, r2 = 2.50, while the integration method gave r1 = 0.097, r2 = 2.91. Application of the integration method to methyl acrylate and methyl methacrylate (M2) gave values of r1 = 0.82, r2 = 0.63; r1 = 0.52, r2 = 1.22, respectively. The curve‐fitting method gave r1 = 0.15, r2 = 0.16 for acrylonitrile (M2) copolymerizations. From styrene copolymerizations, vinylferrocene exhibited values of Q = 0.145 and e = 0.47.
Elastomers from the copolymerization of conjugated dienes and styrenes containing chlorine
Authors: Halasa A. F. , Adams H. , Hunter C. J. 
Published: April 2003

AbstractCopolymers of 1,3‐butadiene and o‐ and p‐chlorostyrenes have been made by use of alkyllithium initiators. These copolymers have a uniform distribution of the chlorostyrene along the chain, suggesting that the reactivity ratio of 1,3‐butadiene and chlorostyrene is close to unity.
Polymerization of butadiene and vinyl ether with catalyst prepared from π‐allyl nickel halide and organic peroxide
Authors: Matsumoto Tsuyoshi , Furukawa Junji , Morimura Hirohisa 
Published: April 2003

AbstractThe π‐allyl nickel halide–organic peroxide system has been found to be active as catalyst for the stereospecific polymerization of butadiene and polymerization of vinyl ether. Benzoyl peroxide is most effective. The catalyst from π‐allyl nickel chloride or π‐allyl nickel bromide and benzoyl peroxide yields predominantly cis‐1,4 polymer with high activity, whereas the catalyst from π‐allyl nickel iodide affords predominantly trans‐1,4 polymer. The catalyst system can be divided into two parts, a benzene‐soluble and a sentially insoluble component. It is concluded that the catalyst activity originates esbenzene‐from the insoluble nickel complex which is composed of halogen atom, benzoyloxy group of conjugated structure, allyl group, and nickel. A structure is proposed for the complex.
Thermal degradation of poly(alkyl acrylates). II. Primary esters: Ethyl, n‐propyl, n‐butyl, and 2‐ethylhexyl
Authors: Grassie N. , Speakman J. G. , Davis T. I. 
Published: April 2003

AbstractQuantitative analyses of the products of thermal degradation of poly(ethyl acrylate), poly(n‐propyl acrylate), poly(n‐butyl acrylate) and poly(2‐ethylhexyl acrylate) have been made, principally by the combined application of GLC and mass and infrared spectroscopy. Data are recorded in mass balance tables. The major gaseous products are carbon dioxide and the olefin corresponding to the ester group. The minor gaseous products include the corresponding alkane, the alkane/olefin ratio being of the order of 10−2–10−3, and traces of carbon monoxide and hydrogen. The alcohol corresponding to the alkyl group is the major liquid product but there are also traces of monomer and the corresponding methacrylate. Alcohol production exhibits autocatalytic properties. The chain fragment fractions of the products are colored yellow and have average chain lengths of 3.2, 3.3, 3.6, and 5.6 for the ethyl, n‐propyl, n‐butyl and 2‐ethylhexyl esters, respectively. The infrared spectra are similar to those of the parent polymers but with well defined differences. Insolubility develops in the ethyl, n‐propyl, and n‐butyl esters, but the residual material from poly(2‐ethylhexyl acrylate) remains soluble even at very advanced stages of degradation. All of these products and reaction characteristics are accounted for in terms of radical reactions with a unique initiation step.
Polyimidazopyrrolones and related polymers. I. Dianhydrides and o‐acetamidodiamines
Authors: Frost L. W. , Bower G. M. 
Published: April 2003

AbstractSolutions of polyimidazopyrrolone precursors prepared by reaction of tetraamines and dianhydrides in polar solvents tend to crosslink and gel very easily. Substitution of o‐acetamidodiamines for the tetraamines gives stable solutions. A study of cure mechanisms by TGA, infrared, and pyrolysis experiments with polymers and model compounds indicates that the acetylated materials are converted cleanly to imides at 150°C. At temperatures above 350°C, structural changes and further polymerization occur, with little imidazopyrrolone formation. Polymers derived from tetraamines cure by multiple mechanisms but finally yield the imidazopyrrolone structure. The acetylated polymers and copolymers give acceptable laminates but poor films.