bluuebunny/crossref_metadata_2025_split huggingface dataset:
The polymerization of vinyl benzoate. Inhibition by the monomer
Authors: Morrison E. D. , Gleason E. H. , Stannett V. 
Published: April 2003

AbstractThe slow rates of polymerization and the low molecular weights of polymer obtained by the free radical‐initiated polymerization of vinyl benzoate is noted. The kinetics have been investigated and indicate that addition of the growing chain to the aromatic nucleus to form a stable, nonpropagating radical is the probable reason. The chain length and extent of branching are consistent with the observed rates and also with the methyl affinities of similar compounds.
Catalytic reactivity and stereospecificity of organometallic compounds in olefin polymerization
Authors: Furukawa Junji , Tsuruta Teiji 
Published: April 2003

AbstractCatalytic reactivity of organometallic compounds in olefin polymerization is discussed on the basis of the electronegativity of the metal. The transition metal compounds seem to participate in the polymerization as Lewis acids which facilitate the addition of an aluminum alkyl by a concerted mechanism.A mechanism for the stereospecific polymerization is advanced in which hindered rotation around the terminal CC bond in the growing polymer and a specific orientation of a monomer to the polymer chain are assumed.
A light‐scattering study of low pressure polyethylene fractions
Authors: Tung L. H. 
Published: April 2003

AbstractLow pressure polyethylene fractions of molecular weight above 100,000 have been studied by the light scattering method. The presence of long chain branches in fractions of molecular weight above 300,000 was indicated by the data. The molecular weight‐intrinsic viscosity relationship for linear polyethylene chains was found to be [η] = 4.60 × 10−4 M0.725 when tetralin at 130°C. was used as the solvent for the intrinsic viscosity measurements. This relationship gives molecular weights about 1.15 times higher than those found previously by the number‐average molecular weight determination of the fractions.
Light scattering and viscosities of chitosan in aqueous solutions of sodium chloride
Authors: Van Duin P. J. , Hermans J. J. 
Published: April 2003

AbstractChitosan prepared from the pen in the mantle of the squid Loligo was fractionated by precipitation. Two fractions were investigated in aqueous solutions of sodium chloride. Fraction II showed anomalous behavior, which is attributed to molecular association, the extent of which increases with decreasing ionic strength. For fraction I, the intrinsic viscosity appears to increase even more rapidly with the radius of gyration than would be predicted by the free‐draining model. The experimental change in the molecular dimensions as a function of ionic strength is much smaller than predicted by polyelectrolyte theories.
Distribution of components in condensation interpolymers
Authors: Beste Lawrence F. 
Published: April 2003

AbstractThe distribution of components of condensation interpolymers into runs of various lengths is derived as a function of composition, relative reaction rates, and extent of reaction. The most important case considered is the polymer built up from AA and BB type units in equivalent amounts. If the AA units represent several chemical individuals but the BB units are restricted to a single individual (e.g., a mixture of diamines together with a single dibasic acid) and the reaction is homogeneous, then the distribution at complete reaction is independent of any differences in the reaction rates of the various AA monomers. Equations are given which allow one to follow the polycondensation process in detail. It is of particular interest to follow the relative numbers of “homogeneous” molecules (containing only one kind of AA unit) and “mixed” molecules (containing two or more kinds) as functions of the extent of reaction, the relative rate constants, and the length of the average run.
A study of the scattering of visible light by polymer particles precipitated from dilute solution
Authors: Hastings G. W. , Peaker F. W. 
Published: April 2003

AbstractThe turbidimetric titration method of analysis of polymer solutions is widely used, but there is some doubt regarding the exact quantitative nature of these determinations. The polymer is precipitated from dilute solution, but these insoluble particles are not always of uniform shape or size; hence, the change in optical density of the solutions, as measured by light transmission, cannot be related directly to the quantity of material precipitated. Light scattering studies made on these fine dispersions of polymeric material has shown that initially these particles are spherical, but that aggregation occurs as the titration proceeds. Attempts to prevent this form of aggregation by the addition of anionic and cationic surface active agents has so far proved unsuccessful.
Infrared spectra of vinylidene chloride‐vinyl chloride copolymer
Authors: Narita S. , Ichinohe S. , Enomoto S. 
Published: April 2003

AbstractObservation of the infrared spectra of vinylidene chloride and vinyl chloride copolymers permitted clarification of some points which were rather ambiguous from the study of the homopolymers, and gave some information on the bands of the copolymers. In particular, the band at 868 cm.−1, which had been considered to be that of polyvinylidene chloride, was observed only in the copolymer. Depending on the mode of arrangement of vinylidene chloride and vinyl chloride in the copolymer, the CH‐deformation frequency appears at 1206, 1245, or 1255 cm.−1. The same behavior was observed with vinylidene chloride‐vinyl bromide copolymers. With the copolymer rich in vinylidene chloride, the band at 1206 cm.−1 can be used for determination of vinyl chloride content. In deuterated vinylidene chloride‐vinyl chloride copolymer, the CD2‐bending frequency due to the CDClCD2CCl2sequence appears at 1081 cm.−1.
Flow testing of viscoelastic materials. Design and calibration of the Roberts‐Weissenberg Model R8 rheogoniometer
Authors: Jobling A. , Roberts J. E. 
Published: April 2003

AbstractThe rheogoniometer is an instrument for the analysis in space and time of the complete stress distribution in a viscoelastic liquid subjected to a known shearing action. A greatly improved form of the instrument is described which affords increased accuracy, electronic measurement of the various components of stress for rapid recording, and a more elaborate drive. This incorporates in a single instrument the alternative actions of unidirectional laminar shear, oscillatory laminar shear, a superposition of these two, and a predetermined acceleration to or deceleration from the first type. With this drive, an independent vibrational analysis of the mechanical properties of the material in its “rest” state or in any steady state of shear can be made.
Molecular adsorption characteristics of matrix‐formed adsorption polymers
Authors: Wagner Herman B. 
Published: April 2003

AbstractThe synthesis of several organic, adsorptive, “replica gels” is described. The technique employs anhydrous silica gel particles as a parent matrix, within which is accomplished the polymerization of a liquid monomer or prepolymer. Following this polymerization the silica gel matrix is selectively dissolved and in this manner removed from the newly formed organic polymer. The adsorption characteristics of these capillary containing substances is given for water and several organic vapors, and the effect of hydrofluoric acid and sodium hydroxide, as matrix solvents, is described. A comparison of observed versus calculated pore volume is made. Absence of hysteresis effects in the adsorption characteristics is noted.
Stress relaxation studies of scission in rubber vulcanizates
Authors: Mercurio A. , Tobolsky A. V. 
Published: April 2003

AbstractThe method of stress relaxation has been used to study oxidative scission in crosslinked rubbers of five different chain structures. Each chain structure was crosslinked by sulfur and by a nonsulfur‐containing agent. Among the sulfur‐cured vuleanizates the rate of scission varied very significantly with chain structure in spite of the presence of sulfur crosslinks in each. On the contrary, for natural rubber, GR‐S, and butyl rubber, the rates of scission of the sulfur cures were not very different from the corresponding sulfurless cures. It was concluded that in these three cases the scission reactions occur predominantly along the network chains as opposed to scission at the crosslinked site.
An x‐ray study of partially benzylated cotton cellulose
Authors: Creely Joseph J. , Stanonis David J. , Klein Elias 
Published: April 2003

AbstractAn X‐ray study has been made of partially benzylated cellulose obtained from mercerized cotton yarn, in accordance with a recently developed technique. This study reports the formation of a new crystal lattice for benzylcellulose with a degree of substitution less than 1. This new lattice is indicative of a considerable distension of the original cellulose II unit cell present in the mercerized yarn. Attempts to benzylate ramie fibers under the same conditions resulted in destruction of the fibrous structure by the treatment. Application of heat and tension were found to cause considerable improvement in crystallinity and degree of crystallite orientation of the benzylated cotton. Application of pressure in preparing the sample for X‐ray analysis in the usual manner was found to affects the X‐ray diffraction pattern, due possibly to distortion of the greatly distended (101) interplanar spacing.
Properties of the statistical polymer as applied to amylopectin and glycogen
Authors: Erlander Stig R. 
Published: April 2003

AbstractIt is shoen that all everage exterior and interior branch lengths of A‐R‐B2 type condensation polymers are equal in length. Because of this, each configuration in the less random statistical model V is an average of all similarly constructed configurations found in the more variable statistical model. Consequently, certain structural properties of the statistical polymer can be examined by using all the configurations of a given x‐mer from the less random model V. The statistical model and partially “debranched” statistical model were used to represent glycogen and amylopectin, respectively. These polymers were theoretically degraded by “phosphorylase” and “amylo1,6‐glucosidase.” Rabbit muscle glycogen behaves as a statistically formed polymer. On the other hand, rabbit liver glycogen behaves as if a large amount of 1,3‐linkages were present in its structure and/or behaves as lif it had been debranched by an enzyme such as the R‐enzyme. When compared to corn amylopectin, wheat amylopectin behaves as if more of its inteerior branches had been removed. Myrbäck and Sillén's statistical model and Bourne and Peat's pseudo‐amylose mechanism are discussed.
Molecular distributions in polycondensations involving unlike reactants. III. Distributions arising in the linear coupling of single polymers
Authors: Case L. C. 
Published: April 2003

AbstractThe molecular distributions arising in the coupling of linear polymers are treated in this paper. The distributions are similar to those arising in single‐stage polycondensations, but are more complex. Multi‐stage polycondensations lead to extremely complex distributions. Frequently the distributions of coupled polymers are quite similar to those of the geometrical. However, if the polymer chains to be coupled are quite different from the geometrical in distribution, or if very unsymmetrical coupling agents are used, the coupled polymers may be much narrower than geometrically distributed polymers. In the limit, it is possible to achieve essentially monodisperse polycondensates using multi‐stage condensation.
Infrared spectrum of polyvinyl chloride. II
Authors: Narita S. , Ichinohe S. , Enomoto S. 
Published: April 2003

AbstractIn order to assign the CH, CH2‐vibration modes and the skeletal modes in the spectrum of polyvinyl chloride, we obtained deuterated polyvinyl chloride and the infrared spectrum of it, and we assumed that frequencies of the skeletal modes and the C‐Cl stretching modes may not change drastically by deuteration. The frequencies of the bands of polyvinyl chloride at 1428, 1333, and 1255 cm.−1 were largely shifted by deuteration and we assign the 1428 cm.−1 band to the CH2‐bending mode and the bands at 1333 and 1255 cm.−1 to the CH‐deformation modes. As the frequency of the band at 1094 cm.−1 was not largely shifted, we assign it to the skeletal stretching mode. As the band at 969 cm.−1 separated into two components at 937 and 787 cm.−1 by deuteration, we believe that this band consists of two overlapped bands, one caused by the skeletal stretching mode and the other by the CH2‐rocking mode. Both the band of polyvinyl chloride at 837 cm.−1 and the band of the deuterated polymer at 806 cm.−1 disappear when they are molten. We think these two bands correspond to each other and assigned them to the skeletal stretching modes.
A novel catalytic polymerization of olefins. Part I. Metal‐metal halide catalysts for high polymerization of lower olefins
Authors: Fukui Kenichi , Kagiya Tsutomu , Shimidzu Takeo , Yagi Tetsuya , Mahi Sueo , Yuasa Sachio , Hirata Minoru , Kodama Shinjiro 
Published: April 2003

AbstractThe high polymerization of ethylene and propylene is studied by a novel catalyst which consists of metals and metal halides. Titanium halides with metallic aluminum, magnesium, or zinc are able to accelerate the polymerization of ethylene to produce a high polymer at 50‐250°C. and under the pressure of 1‐200 atoms. In the presence of metallic aluminum, the activity of titanium halides descreases with the valency of titanium. The effect of milling of metals in titanium halide solution is also studied. This treatment is found to lower the rate of reaction. An extremely high molecular polyethylene is synthetized by an appropriately chosen mixed halides catalyst. Polyethylene produced has melting point ranging from 120‐135°C., molecular weight being as high as some hundreds of thousand. Tensile strength is 100‐250 kg./cm.,2 specific gravity is 0.94‐0.95. The number of CH3 groups as well as of CC double bonds in small and crystallinity is considerably higher than high pressure polyethylene. This catalyst is also applied to the polymerization of propylene. A solid polypropylene melting at 140‐155°C. is produced.
Lithium‐initiated copolymerization of styrene and methyl methacrylate. III
Authors: O'driscoll K. F. , Tobolsky A. V. 
Published: April 2003

AbstractData are presented for copolymer composition as a function of monomer composition in the system styrene‐methyl methacrylate initiated by lithium in tetrahydrofuran and hydrocarbons. The data are interpreted in the light of the electron exchange initiation and ion‐radical propagation mechanisms previously proposed. Revised r1 and r2 values for strictly anionic copolymerization of styrene and methyl methacrylate are presented on the basis of data obtained with the use of n‐butyllithium and phenylsodium as typical anionic initiators in hydrocarbons. Sodium dissolved in liquid ammonia and sodium dispersion in hydrocarbons gave results identical with those obtained with true anionic catalysts. This is in sharp distinction to the results obtained with lithium.
Dielectric dispersion of ethyl cellulose in n‐butyl acetate solution
Authors: Scherer P. C. , Hawkins M. C. , Levi D. W. 
Published: April 2003

AbstractBy measuring the capacity change of ethyl cellulose in n‐butyl acetate solutions and determining the frequency at which the dielectric dispersion is 0.50, the same general dependence of the intrinsic viscosity on the critical frequency was found as has already been reported for solutions in other solvents. The difficulty in measuring capacities for solutions of high dissipation factor could be overcome either by using a special resistance network with the bridge, or by inserting large values of capacity in parallel with the bridge arms. The latter procedure appears to offer possibilities for use with solvents of still higher dielectric constant and is being investigated at present in this laboratory.
Graft copolymers from polymers having pendant mercaptan groups. I. Kinetic considerations
Authors: Fox T. G. , Gluckman M. S. , Gornick F. , Graham R. K. , Gratch Serge 
Published: April 2003

AbstractA general kinetic analysis of the polymerization of a monomer in the presence of a pre‐formed polymer having chain transfer sites of high activity is presented. Equations are given predicting both the grafting efficiency and the molecular weights of interest. Most of the results are expressed in terms of definite integrals which, except for special values of C8, require numerical evaluation. In most cases, approximate closed form equations can be used. The results are expressed in terms of the polymerization constants of the monomer, the initial rate of polymerization, the fractional conversion to polymer, and the decrease in the concentration of transfer sites.
Graft copolymers from polymers having pendant mercaptan groups. II. Synthesis and characterization
Authors: Gluckman M. S. , Kampf M. J. , O'brien J. L. , Fox T. G. , Graham R. K. 
Published: April 2003

AbstractPolymers containing pendant mereaptan groups can be prepared by the reaction of copolymers containing a small amount of glycidyl methacrylate with an excess of thioglycolic acid. Two mercaptan groups are introduced for each original epoxide group. Chain transfer constants were determined for these groups with styrene and with methyl methacrylate and were found to be similar to those found with simple mercaptans. Free‐radical polymerization of styrene, of acrylate, and of methacrylate monomers in solution at 60°C. in the presence of the pre‐formed mercaptan‐containing polymer produced graft copolymers in high efficiency through chain transfer with the highly active mercaptan sites. The efficiency of grafting was determined from extraction data and by titration of the residual mercaptan groups; the results generally agreed well with those predicted from the theory presented in the companion paper.
Effect of chemical structure on the softening point of substituted polystyrenes and related materials
Authors: Barb W. G. 
Published: April 2003

AbstractThe concept of a limiting softening point, defined in relation to a partictilar standard test method (B. S. 1493) but otherwise only a function of the repeat unit structure of the polymer, is discussed. An approximate correlation of results obtained from different standard methods is given and its limitations analyzed. Limiting softening point data are given for polystyrene and 25 different substituted polystyrenes. Analysis of the results suggest the following: (1) the elevating effect of non‐polar nuelear substituents is greatest in the o‐position, and increases with the size of the substituent (2) in the p‐position, large rigid groups elevate the softening‐point whereas the reverse is true of flexible (articulated) groups; (3) effects of substituents are additive only where they produce the same hindrance to molecular motion, e.g., the effect of two Similar o‐substituents is additive; in other cases, the softening point elevation is determined by the biggest single energy barrier which has to be overcome. (4)Inchlorine‐substituted polystyrenes the L.S.P. can [in accordance with (3)] be determined by either polar or stenic factors, depending on the number and position of the substituents. It is also possible to classify the mechanisms by which substitution can elevate the L.S.P. of polystyrene, these being: (1) stiffening of the main‐chain backbone; (2) intramolecular steric hindrance (e.g., o‐substitution); (3) increased intermolecular steric hindrance; and (4) dipolar attraction. From a qualitative consideration of structural features in copolymers of styrene with substituted styrenes, it is deduced that many such copolymers should show a roughly linear variation of L.S.P. with composition.
Oligomerization of 1,3‐diolefines with ziegler‐type catalysts
Authors: Wilke Güunther 
Published: April 2003

AbstractButadiene‐(1,3) reacts with certain Ziegler‐catalysts almost exclusively according to the principle of the 1,4‐addition to form cyclododecatriene‐(1,5,9). In contrast to that, 2,3‐dimethylbutadiene‐(1,3) follows a new linking mechanism of hydrogen‐transfer to form an open‐chained trimer. Isoprene and piperylene react according to both mechanisms.
Polymer NSR spectroscopy. I. The motion and configuration of polymer chains in solution
Authors: Bovey F. A. , Tiers G. V. D. , Filipovich G. 
Published: April 2003

AbstractMany polymers in solution exhibit well‐resolved NSR spectra, in contrast to the broad peaks observed for the solid state. The peaks for polystyrene dissolved in carbon tetrachloride are not very much broader than those of cumene and other small organic molecules. When segmental motion is restricted or prevented, polymer peaks may become very broad even in solution. This is observed for poly‐γ‐benzyl‐L‐glutamate in trichloroethylene, in which it probably exists as large aggregates of α‐helices. It is shown that the α‐helical conformation itself is not responsible for this broadening. Many proteins also show poorly resolved spectra in the native state, but well‐resolved peaks in the unfolded state. Large “anomalous” shifts observed in the positions of the proton peaks in the NSR spectra of polystyrene and substituted polystyrenes are interpreted in terms of a π‐current model of the benzene ring. It is concluded that where sequences of 10 or more phenyl groups are present on a polymer chain, they tend to cluster together in a quasi‐crystalline arrangement.
An electron microscope study of the growth and structure of spherulites in polyethylene
Authors: Reding F. P. , Walter E. R. 
Published: April 2003

AbstractA surface‐etching technique has been devised which reveals the spherulites in molded Polyethylene for study with the electron microscope. By means of this technique it is possible to observe the effect of various heating cycles and polymer structures on the size and perfection of the spherulites. The etching technique shows that two different types of large spherulites may be formed in polyethylene. One, which may be formed on molding, contains a relatively low amount of internal order. The other, which forms on long heat aging or annealing, contains a high degree of internal order. Heat aging at temperatures well below the melting point will induce the poorly ordered type of spherulite to break up and regrow in the highly ordered form. Spherulite structure was observed to depend not only on heat treatment, but also on chain branching and molecular weight. Increased linearity induces the formation of a more regular, sheetlike or laminated structure within the spherulites, while lower molecular weight causes the lamellae and spherulites as well to be larger in size. Extremely high molecular weight linear resins showed no spherulitic structure as such, but were fibrillar in appearance. Annealing or long heat aging of these resins induced the formation of a row type aggregate structure rather than the typical spherulites observed in normal molecular weight resins. Electron microscope studies of stress‐cracked surfaces indicate that a high degree of internal spherulitic order such as is formed on long heat aging may well be the primary cause of stress‐cracking in polyethylene. This is further indicated by resins such as the ethylene/propylene copolymers, in which highly ordered spherulites do not form with heat aging. These resins are very resistant to stress cracking. Structural studies show that the ethylene/propylene copolymers are very nonrandom, and it is believed that this interferes with the formation of perfect, and consequently crack‐prone, spherulites.