bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of anionic polymerization of styrene
Authors: O'Driscoll K. F. , Tobolsky A. V.
Published: April 2003

The kinetics of the polymerization of styrene initiated by n‐butyl lithium (BuLi) in benzene and in benzene plus small amounts of tetrahydrofuran (THF) have been investigated. It was found that the rate of polymerization is independent of BuLi concentration over a 100‐fold range in pure benzene. In benzene with added THF, the rate is inversely proportional to the BuLi concentration. A reaction scheme is suggested to expalin these unusual kinetics.
Graft copolymers from poly(styrene co dimethyl maleate) and poly(styrene co allyl acetate)
Authors: Weiss P. , Gerecht J. F. , Krems I. J.
Published: April 2003

Graft copolymers, were synthesized from hydrophobic backbone copolymers by introducing hydrophilic grafts at appropriate juncture points. Poly(styrene co dimethyl maleate) of varying composition was prepared by the copolymerization of styrene with dimethyl maleate in the presence of benzoyl peroxide as the initiator. Data on conversion rates of initial monomers to copolymer, infrared measurements, limiting viscosity numbers, and copolymer compositions are presented. The poly(styrene co dimethyl maleate) was resistant to saponification but, when reacted with sodium catalyzed monoethanolamine at its boiling point, yielded the desired poly(styrene co maleic ethanolamide). Addition of ethylene oxide to the available hydroxyl groups yielded, in some instances, water‐dispersible graft copolymers. Poly(styrene co allyl acetate) was prepared by copolymerizing styrene with allyl acetate with use of benzoyl peroxide as the initiator. Water‐dispersible copolymers from this backbone copolymer were prepared by saponification of the acetate groups and the grafting of ethylene oxide to the available hydroxyl groups in the backbone copolymer. Results of analyses, molecular weight determination, and infrared measurements are presented.
High‐energy radiation effects on polyacrylates and polymethacrylates
Authors: Shultz Allan R.
Published: April 2003

Chemical and physical changes produced in polymethacrylates and polyacrylates by ionizing radiations are examined in the light of data revealing molecular structural changes and ultimate fragmentation products. A 1,4‐diradical or concerted mechanism is postulated for polymethacrylate main‐chain scission.
Vapor pressures of polymer solutions. I. Apparatus for measurement and some results on poly(vinyl acetate) solutions
Authors: Nakajima Akio , Yamakawa Hiromi , Sakurada Ichiro
Published: April 2003

An apparatus is described for the measurement of the vapor pressures and concentrations of high polymer solutions. Results are given for the poly(vinyl acetate)‐benzene and poly(vinyl acetate)‐vinyl acetate systems. For both, the interaction constant, χ12, decreases linearly as the volume fraction of polymer increases from 0.4 to 0.9.
Vapor pressures of polymer solutions. II. Vapor pressure of the poly(vinyl alcohol)‐water system
Authors: Sakurada Ichiro , Nakajima Akio , Fujiwara Hiroyuki
Published: April 2003

Vapor pressures were measured for the system, poly(vinyl alcohol)‐water at 30°C. with the apparatus reported in the preceding paper. Fractionated samples were used in the form of thin films, carefully dried under high vacuum at room temperature. The degree of crystallinity of these samples was about 0.2, and the degrees of polymerization were 1530 and 335. The relation between the activity of the water and the composition of the gel phase is discussed. The interaction parameter χ12 is evaluated assuming that the crystalline regions are not affected by the water and correspond to the crosslinks in an amorphous network polymer; also that the chain length between two crosslinks is not changed with the composition of the system. χ12 increases with increasing polymer concentration. This behavior is discussed with the aid of heat of dilution data from the literature. The anomalous concentration dependence of the entropy and energy contributions to χ12 may be explained as resulting from the mutual orientation of water molecules and the hydroxyl groups along the polymer chain.
Moisture permeability of polymers. I. Role of crystallinity and orientation
Authors: Lasoski S. W. , Cobbs W. H.
Published: April 2003

With three polymers widely different in polarity—polyethylene terephthalate, polyethylene, and nylon 610—the water vapor permeability P of unoriented films has been shown to increase as the amorphous fraction Xa is increased, following the relation P = PaXa2. For polyethylenes, adherence to this relation is exhibited only with structures having densities above 0.94, a range in which the number of short chain branches is low. Films with densities lower than 0.94 exhibit higher film permeabilities than those calculated on the basis of the permeability of the amorphous areas Pa of “linear” polyethylene; this results from the increase in the number of short chain branches and hence, an increase in Pa of the lower density polyethylenes. The above variation of water vapor permeability with the square of the amorphous fraction may be theoretically accounted for by a linear variation of the diffusion and solubility coefficients with the amorphous fraction. With polyethylene terephthalate and nylon 610, the solubility coefficients do exhibit this linear relation. The square permeability relation appears to be a limiting case for structures in which crystallization does not impose restraints on the segmental motions important in permeability. Where restraints do occur, as in oriented films, a higher order dependency on the amorphous fraction exists. This was exemplified with biaxially and uniaxially oriented polyethylene terephthalate films, with which it was shown that orientation in oriented crystalline films effects a decrease in permeability in addition to that ascribable to crystallinity. This is not true for such films as polystyrene or stretched rubber which has not crystallized. Only those oriented structures in which the orientation is “locked‐in,” as by crystallization, exhibit a decrease in water vapor permeability. The relations of permeability and solubility coefficients to crystallinity have an important utility in that the extent of crystallinity or crystal density may be estimated with the proper data. On the basis of literature water vapor permeability data of Szwarc et al. for two high density polyethylenes at three different vapor pressure differentials, the crystal density of polyethylene was estimated to be 0.995, 1.008, and 0.998 or an average of 1.00, in agreement with Bunn's value calculated on the basis of x‐ray diffraction studies.
Copolymerization of methacrylic acid esters with methacrylonitrile
Authors: Cameron G. G. , Grant D. H. , Grassie N. , Lamb J. E. , McNeill I. C.
Published: April 2003

The reactivity ratios in the copolymerization of methacrylonitrile with styrene, methacrylic acid, and eleven alkyl methacrylates have been determined and the Alfrey‐Price Q and e values calculated. Monomer reactivity in these systems is principally a function of resonance stabilization (Q), polar factors (e) playing a relatively minor role. With the exception of the stearyl ester, the changes in the Q and e values which occur on ascending the homologous series can be accounted for qualitatively in terms of the expected relative electronic displacements and of the steric effects caused by the various alkyl groups. Some correlation between monomer reactivity and the depolymerizability of the corresponding polymer has been noted.
Polymerization of dichlorophosphinic nitrides
Authors: Konecny Jan O. , Douglas Catherine M.
Published: April 2003

The polymerization of the trimer and tetramer of dichlorophosphinic nitride was found to be catalyzed by a variety of organic compounds: ethers, carboxylic acids and ketones, and also by metals. The effect of these substances on the polymerization rate at 211° was explored quantitatively. The tetramer was invariably found to react slower than the trimer, and the same order of reactivities was observed in the copolymerization of the two materials. The catalysts all displayed a comparable activity.
Crystallization kinetics and mechanical properties of polyethylene
Authors: Buchdahl R. , Miller R. L. , Newman S.
Published: April 2003

The kinetics of crystallization of a branched polyethylene have been studied dilatometrically, spectroscopically, and microscopically at small degrees of supercooling (ca. 0–10°C.). In order to assess the extent to which results of different methods are in agreement with each other, apparent induction times and maximuin crystallization rates are compared. On the basis of these data, the results of different experimental techniques using different types of sample are in general agreement. However, there do exist small, but significant, differences which appear to be outside experimental error. The results are shown to be in essential agreement with present theories of nucleation and of crystallization. The observations are interpreted in terms of the processes occurring during crystallization. The relationship of dynamic mechanical properties to previous thermal histories is considered and a qualitative interpretation is presented.
The polymerization of vinyl benzoate. Inhibition by the monomer
Authors: Morrison E. D. , Gleason E. H. , Stannett V.
Published: April 2003

The 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

Catalytic 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

Low 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

Chitosan 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

The 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

The 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

Observation 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

The 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

The 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

The 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

An 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

It 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

The 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

In 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

The 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

Data 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

By 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

A 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

Polymers 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

The 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

Butadiene‐(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

Many 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

A 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.
Colligative properties of polyelectrolyte solutions. VI. Donnan membrane equilibrium
Authors: Nagasawa Mitsuru , Takahashi Akira , Izumi Mikio , Kagawa Ikumi
Published: April 2003

The Donnan membrane equilibrium of a linear polyelectrolyte solution was studied, using sodium polyvinyl alcohol sulfate as the sample and sodium chloride as the diffusible salt. Simultaneous measurements of membrane potential, sodium and chloride ion activities, sodium chloride distribution, osmotic pressure, and viscosity were carried out. The measurements of membrane potential and ionic activities gave consistent results which could be accounted for by the Donnan theory. The second virial coefficient, which was found to be much lower than the ideal Donnan term, was examined according to Scatchard's theory. It was found that while the theory gave a good qualitative explanation to the experimental results, it could not be used for quantitative discussion. For quantitative examination of the experimental second virial coefficient, the value of second virial coefficient was calculated from the assumption that osmotic pressure is proportional to the difference of the sum of solute activities on both sides of membrane, and was found to be nearly equal to the observed value.
The dimers of isoprene
Authors: Binder John L. , Eberly Kenneth C. , Smith George E. P.
Published: April 2003

The cyclic C6 and C8 dimers of isoprene have been prepared by thermal dimerization and their physical and chemical properties obtained. The infrared spectra of these substances are also given and are used to confirm the structures deduced chemically.
The kinetics of radical polymerization of ethylene. I. General kinetics
Authors: Laita Z.
Published: April 2003

Photosensitized polymerization of ethylene in benzene solution has been studied at 83°C. using azoisopropane as initiator. Experiments were conducted in the concentration range from 6.5 to 28.1 wt.‐% of ethylene and at pressures equal to the vapor pressure of the solutions. The apparent order of reaction with respect to the monomer varies from 1 to 1.5. The intensity exponent exceeds 0.5 and increases with increasing initiator concentration. Chain transfer constants with monomer, solvent, and initiator have been determined. Their values are: k4/k2 = 5 x 10−4, ks/k2 = 2 x 10−3, and kK/k2 = 0.5 ± 0.1, respectively.
Endgroups in tetrafluoroethylene polymers
Authors: Bro M. I. , Sperati C. A.
Published: April 2003

The aqueous polymerization of tetrafluoroethylene initiated with ammonium persulfate in neutral or relatively weak acid solutions leads to polymer containing carboxyl end groups. The conversion of this endgroup to the sodium salt and its pyrolysis to the terminal olefin was followed, using infrared absorption technique.
A theory of the thermodynamic behavior of non‐electrolyte solutions
Authors: Maron Samuel H.
Published: April 2003

A nonstatistical theory has been developed to account for the heat, entropy, and free energy changes accompanying the formation of binary non‐electrolyte solutions, and for associated thermodynamic properties such as activities, activity coefficients, osmotic pressures, and light‐scattering behavior. The theory considers the volume changes occurring during solution, the effective volume occupied by the molecules, their relative size, and their interactions as a function of temperature and concentration. Since the approach was general in character, the theory should be applicable to polymer solutions as well as to solutions of low molecular weight substances.
Molecular weight distributions for polydisperse systems
Authors: Schumaker Verne N.
Published: April 2003

In this communication, equations are developed which allow the calculation of well defined average molecular weights and molecular weight distributions for unfractionated polydisperse polymer systems by appropriate combinations of the results of sedimentation, viscosity, and diffusion measurements. This theoretical approach is based upon the existence, for the polymer‐solvent system being studied, of a simple equation relating molecular weight to sedimentation coefficient. The particular equation chosen in this communication is the relation M = ASγ where M and S are the molecular weight and the sedimentation coefficient, respectively, and A and γ are constants for polymer‐solvent system being studied. The equations developed show how the constants A and γ may be determined from measurement of other hydrodynamic properties such as the diffusion coefficient and the intrinsic viscosity of the unfractionated system. Systems which are homogeneous with respect to molecular weight but polydisperse in shape are also considered, and equations are developed for determining the molecular weight of such preparations. Finally, systems polydisperse both with respect to shape and molecular weight are examined, and a possible method for the molecular weight characterization of such systems is presented.
The polymerization of acrylamide initiated by ceric nitrate‐3‐chloro‐1‐propanol redox systems
Authors: Mino G. , Kaizerman S. , Rasmussen E.
Published: April 2003

The polymerization of acrylamide initiated by ceric nitrate and 3‐chloro‐1‐propanol was studied in aqueous solution at 25°C. At constant hydrogen ion and nitrate ion concentration, the rate of polymerization was found to be independent of the ceric ion concentration. The molecular weight of the polymer was very low. To explain the data, a kinetic scheme is proposed whereby ceric ions are responsible for both initiation and termination. The rate constant for oxidative termination was found to be of the order of 105 l. mole−1 sec.−1 and varied with the hydrogen ion and the nitrate ion concentrations.
Triazines. XX.1s‐triazine as a new co‐reactant in polymer synthesis
Authors: Grundmann Christoph , Kreutzberger Alfred
Published: April 2003

Trimeric hydrogen cyanide, the structure of which has recently been established as striazine, exhibits as most characteristic phenomenon a marked readiness to undergo ring cleavage upon the action of nucleophilic reagents. This susceptibility to ring cleavage makes s‐triazine an important source for methine (CH) groups by means of which other functional groups can be linked each other. Advantage has been taken of the methinylation capability of s‐triazine to link the functional groups in diamines. While the lower members of the aliphatic diamine series, i.e., ethylenediamine and 1,3‐propanediamine, react With s‐triazine to give cyclic compounds, higher diamine homologs like 1,5‐pentanediamine and 1,6‐hexanediamine furnish exclusively open chain polymers termed polyamidines. 1,4‐Butanediamine, being on the verge of these two diamine categories, forms both the cyclic compound and the open chain polymer. In the polyamidine synthesis, the successful isolation of intermediates furnishes an informative picture of the mode of formation. In view of the fact that other functional groups, e.g., SH, NHNH2, and OH, are amenable to this reaction also, s‐triazine may be considered as a novel important starting material for new types of chain‐like polymers containing hetero atoms.
Adsorption of polymers: Polystyrene on carbon
Authors: Frisch H. L. , Hellman M. Y. , Lundberg J. L.
Published: April 2003

The adsorption of polystyrene from toluene solution on a carbon black has been studied at 25°C. under varying conditions of dryness. The isotherm for adsorption on the relatively dry carbon black exhibited a characteristic steep initial rise as a function of concentration and attained a saturation value. Larger molecules appear from intrinsic viscosity studies to be adsorbed preferentially. The rate of desorption appears to be so low that, for time periods of the order of two weeks, the adsorption of polystyrene is effectively irreversible. The total adsorption of polymer is decreased by extreme drying and by saturating the system with water.
The kinetics of radical polymerization of ethylene. II. Determination of the kinetic coefficients
Authors: Laita Z. , Macháček Z.
Published: April 2003

By the method of intermittent illumination, the kinetic coefficients for monoradical termination, mutual termination, and propagation at 83°C. have been evaluated. It has been found that monoradical termination is caused by azoisopropane only. The rate of initiation has been determined both by the molecular weight method and by the inhibitor technique. From the comparison of results, it follows that the predominating termination reaction is disproportionation. The values of the kinetic coefficients are:

Propagation
k2 = (4.7 ± 0.3) × 102 1./mole‐sec.

mutual termination
k3 = (1.05 ± 0.05) × 109 1./mole‐sec.

monoradical termination
k5 = l.85 × 102 1./mole‐sec.

transfer with monomer
k4 = 0.25 l./mole‐sec.

transfer with benzene
kS = 1.0 l./mole‐sec.
The infrared spectrum of polyethylene terephthalate. I The effect of crystallization
Authors: Miyake Akihisa
Published: April 2003

Films of amorphous polyethylene terephthala were drawn and heated to various extents. Intensity change of the infrared spectral bands resulting from these treatments were followed. There are more than seven bands which change their intensities by drawing, and sixteen bands affected by heat treatment. Exactly the same changes are also observed in several aromatic esters of ethylene glycol. The bands that intensify in the crystalline state of these model compounds correspond to the crystalline bands of polyethylene terephthalate, and the bands that appear in the melt of model compounds correspond to the amorphous bands of polyethylene terephthalate. Main crystalline bands and all of the amorphous bands are associated with ethylene glycol residue. A crystalline band makes a couple with one of the amorphous bands and the frequencies of this couple have reasonable values as the characteristic vibration of the ethylene glycol residue. Thus, the spectral change can be interpreted by the rotational isomerism of the ethylene glycol residue, the gauche form in the amorphous part changing into the trans form by crystallization. The crystalline band at 973 cm. −1 corresponds to the Bu type CO stretching vibration of the trans form, and the amorphous bands at 1099 and 1042 cm.−1 correspond to A and B type CO stretching vibrations of the gauche form. The crystalline bands at 1475, 1387, and 988 cm. −1 are considered to be manifestations of the perturbation of the crystal field.
The infrared spectrum of polutrthylene terephthalate. II. Polyethylene‐d4 terephthalate
Authors: Miyake Akihisa
Published: April 2003

Polyethylene‐d4 terephthalate was prepared from dimethyl terephthalate and 1,2ethane‐d4‐diol. This polymer also showed spectral changes by drawing and heattreatment as in the case of polyethylene terephthalate. Comparison of the deuterated polymer spectrum with that of ordinary polymer, reveals the bands associated with ethylene glycol residue quite clearly. Almost all the bands which change their intensities by crystallization, belong to ethylene glycol residue vibration. From the shifts on deuteration, the bands of polyethylene terephthalate at 1101, 1042, and 973 cm.−1 are assigned to C‐O vibrations. Vibrational frequencies associated to terephthalic acid residue remain unchanged on deuteration of the ethylene glycol residue. Assignments for p‐substituted benzene residue are given, based on the assignments of benzene, p‐benzene‐d2, p‐xylene, etc. The bands at 873 and 727 cm.−1 are both assigned to the coupled vibrations of aromatic out‐of‐plane CH bending mode and out‐of‐plane OCO bending mode. These two modes seem to have a considerable interaction with each other in aromatic esters.
Conformation of linear chains and their mode of packing in the crystal state
Authors: Natta Giulio , Corradini Paolo
Published: April 2003

Some general rules regarding the conformation and mode of packing of macromolecular chains in crystals are illustrated. The monomeric units occupy equivalent positions in regard to the axis of the chain. It follows that crystallizable polymers must have a type of regularity which will enable them to assume the helix‐ or glide‐plane conformation. Energy considerations lead to other rules regarding the conformation and the mode of packing of the chains. Isosterism phenomena leading to statistical substitution of chains in the lattice and to the existence of planes, along which the macromolecules pack preferentially are considered. The structures of isotactic and syndiotactic polymers, and of all four stereoisomeric polybutadienes are discussed.
The relations between intrinsic viscosity and molecular weight for partially alcoholized polyvinyl acetates
Authors: Beresniewicz A.
Published: April 2003

Viscosities of partially alcoholized polyvinyl acetates were measured at 25°C. using water as solvent. The intrinsic viscosity decreases, whereas the Huggins constant, k′, increases with increasing fraction of nonalcoholized acetate groups in the polymer. A plot of the viscosity of a 4.0% solution against the degree of alcoholysis exhibits a minimum approximately at 87% alcoholysis. The following equation was established, which expresses the intrinsic viscosity of partially alcoholized polyvinyl acetate as a function of the fraction of alcoholized acetate groups, α, and of the molecular weight:

It is shown that in partially alcoholized polyvinyl acetate the larger molecules are somewhat more completely alcoholized than the smaller ones. The resulting heterogeneity with respect to the degree of alcoholysis affects the efficiency of fractionation of such a polymer with respect to its chain length.
Investigations on banded spherulites
Authors: Keller A.
Published: April 2003

The nature of banded spherulites was further investigated. The principal material used was a polyester, namely, polytrimethylene glutarate, but use was made also of nonpolymeric materials. A variety of observations on extinction effects with the Universal Stage conclusively confirmed the twisted crystal model of banded spherulites. It is shown that banding observed in the form of other than extinction effects need not indicate a zone structure. Such bands can be due to diffraction effects or pseudopleochroism following from the twisted structure, examples of such effects being quoted. In some cases, genuine rhythmic distribution of matter was observed, and it is shown that these effects arise in two‐dimensional spherulites only, and can still follow from the twisted morphology under the influence of a substrate. Direct observations of a helicoidal morphology are also quoted.