bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calculation of the copolymerization parameters in the ternary copolymerization system of styrene/m‐divinyl‐benzene/p‐divinylbenzene
Authors: Schwachula G. 
Published: June 2010

AbstractThe r‐values of styrene with p‐divinylbenzene or m‐divinylbenzene (DVB), respectively, as determined by several authors, deviate strongly from the ideal straight line in the binary polymerization diagram. In an attempt to convert the various r‐values into coincident e‐and q‐values according to the equations of Schwan and Price. log r1 = (1 T) [6.79 (q1 ‐ q2) ‐ 3.63 1( 1 – 2)] and log r2 = (‐ 1 T) [6.79 (q1 ‐ q2) + 3.63 2 ( 1 ‐ 2)] good agreement was found for several r‐values, while others gave results that could not be evaluated. From a couple of ‐ and q‐values of p‐divinylbenzene and m‐divinylbenzene, the unmeasured r‐values between p‐divinylbenzene and m‐divinylbenzene were computed according to Schwan and Price. Using these r‐values, the ternary, copolymerization system of styrene m‐divinylbenzene/p‐divinylbenzene was computed approximately for various molar ratios of p‐divinylbenzene to m‐divinylbenzene (2:1 1:4) according to Alfrey and Goldfinger. It was shown that p‐divinylbenzene has an essential influence on heterogeneity in a ternary system, too.
Functional monomers and polymers containing nucleic acid bases
Authors: Takemoto Kiichi 
Published: June 2010

AbstractIn order to prepare simply designed, nucleic acid analogs, a series of monomeric compounds containing purine and pyrimidine bases, such as vinyl, epoxy, dicarboxylic acid, propanediol and amino acid types, were synthesized. By polymerizing and polycondensing these monomers, different types of synthetic polymers with functional side groups were successfully obtained. As for the properties of the polymers prepared, base‐base interactions were studied in detail by measuring ultraviolet, NMR, and emission spectra. By utilizing these specific absorption characteristics, application for separating special base from base mixtures by chromatographic techniques is possible. High polymers with stereoregular structures were prepared which could be used as matrices for template polymerization using special base‐base interaction, as observed widely in the natural nucleic acid molecules. Further problems are considered and discussed.
Temperature dependence of the structure‐forming processes in gelatin films
Authors: Coopes I. H. 
Published: June 2010

AbstractThe development of structural order in gelatin films dried at various temperatures is studied by means of optical rotation and lateral swell measurements. The films, which are very thin and are dried quite rapidly, have a comparatively low proportion of helical content. A certain degree of orientation of amino acid units in the nonhelical segments is suggested. The variation of rate of helix formation with temperature is found to follow a modified Flory‐Weaver equation. This relationship is confirmed by lateral swell data.
Spectroscopic observation of the propagating species in the cationic polymerization of vinyl monomers
Authors: Kunitake Toyoki , Takarabe Kunihide 
Published: June 2010

AbstractThe reaction of several vinyl aromatic monomers with CF3SO3H and H2SO4 was carried out in di‐chloroethane at 30°C. The rapid formation of the cationic species was followed by the stopped‐flow method, and the transient species were identified by rapid‐scan spectra and rapid quenching of the reaction mixture. The monomeric cation was formed predominantly in the reaction of 1,1‐diphenylethylene and excess CF3SO3H; however, an indanic dimer was formed in the presence of excess diphenylethylene. The rate constant for the formation of the cationic species was (3∼4) × 103 M−1.sec−1. On the other hand, the reaction of diphenylethylene and H2SO4 produced two short‐lived species: the monomeric cation and, probably, a monomeric radical cation. The transient species (lifetime ∼50 msec) were similarly observed in the reaction of CF3SO3H with styrene, methylstyrenes, and indene.
Alkyl halides in conjunction with inorganic salt for the initiation of the polymerization and graft copolymerization of heterocycles
Authors: Dreyfuss P. , Kennedy J. P. 
Published: June 2010

AbstractWhen certain alkyl halides react with suitable inorganic salts in the presence of a heterocyclic monomer, polymerization ensues. Appropriate alkyl halides include allylic, tertiary, and benzylic chlorides, bromides, and possibly iodides. If the halide is a small organic molecule, a homopolymer is formed; if it is a polymer halide, a graft copolymer results. Soluble silver salts with counterions such as SO3CF3−, BF4−, PF6−, SbF6−, and ClO4− are most suitable, but LiPF6 and NaClO4 can also be used. So far, nine heterocycles have been polymerized by this method, e.g., tetrahydrofuran, 7‐oxabicyclo[2·2·1]heptane, propylene oxide, styrene oxide, dioxolane, trioxane, ε‐caprolactone, and thietane. To date, no effort has been made to optimize conditions for each monomer, but the preliminary data suggest that many of the expected side reactions are operative. Graft copolymers have been prepared from seven backbones: poly(vinyl chloride), neoprene, chlorinated EPDM, chlorobutyl rubber, bromobutyl rubber, chlorinated butadiene, and chlorinated butadiene‐styrene copolymer. In the most thoroughly examined cases with polytetrahydrofuran as the grafted copolymer and silver triflate as the inorganic salt, current data indicate that no unreacted backbone remains and no homopolymer forms. With some of the other monomers, homopolymer is formed in addition to graft during the grafting process.
Photoinitiated and aprotonically initiated polymerization of olefins by Lewis acids
Authors: Marek M. 
Published: June 2010

AbstractA survey and discussion of recent problems in interpretation of the mechanism of olefin polymerization by Lewis acids is presented from the point of view of new results obtained by study of physicochemical transformations which proceed in interaction of catalysts with olefins. Opinions related to the photo‐chemically initiated cationic polymerization have been further defined by the study of formation and composition of complexes as well as by analysis of oxidation‐reduction processes proceeding under the effect of light on the reaction mixture. The formation of radicals under the effect of visible light in the presence of Lewis acids was proved with several monomers other than isobutylene. During investigation of the role of products from the photooxidation‐reduction processes in the polymerization of isobutylene, it has been found that strongly basic reducing agents, such as butyllithium, cause the polymerization of isobutylene in the presence of halides of tetravalent transition metals.Also analyzed are the aspects of utilization of the photochemically induced polymerization in development of new technological procedures for manufacturing of high molecular weight polyisobutylene and butyl rubber under economically advantageous conditions.
Rates of initiation of the cationic polymerization of isobutene
Authors: Russell Kenneth E. , Vail Linda G. M. C. 
Published: June 2010

AbstractThe substance 2,6‐di‐tert‐butylphenol acts as a strong retarder for the cationic polymerization of isobutene. Spectroscopic studies show that the growing polymer cation attacks the phenol at the basic 4‐position. Analysis of the kinetic and degree of polymerization results yields estimates of the rates of initiation of the polymerization.The initiation reaction in the polymerization of isobutene in ethyl chloride at −78.5°C with stannic chloride and a coinitiator appears to be a first‐order process. Rate constants for the initiation reaction include 4 × 10−6sec−1 for water as coinitiator, 3.8 × 10−5sec−1 for 2,6‐dimethylphenol, 7.5 × 10−5sec−1 for 2,4,6‐trimethylphenol, 3.1 × 10−5sec−1 for 2,3,5,6‐tetramethylphenol, 7 × 10−5 sec−1 for 2,3,4,6‐tetramethylphenol, and 1.5 × 10−3sec−1 for acetic acid.
Olefin oligomerization by boron fluoride
Authors: Lachance Pierre , Eastham Arthur M. 
Published: June 2010

AbstractPolymerization of 2‐butene by boron fluoride‐methanol in methylene chloride gives a mixture of olefins, primarily in the C8–C14 range. The C8 fraction consists of the equilibrium mixture of 3,4‐dimethylhexenes corresponding to the normal dimer; similarly, the C10 fraction is largely a mixture of 3,4,5‐trimethylheptenes. The major component of the C9 group seems to be a 2,3,4‐trimethylhexene, but a significant part of the nonenes remains unidentified. We now have evidence, in contradiction to our earlier report, that a C11 fraction does exist but is difficult to separate from the complex C12 mixture.With propylene under the same reaction conditions, limited fragmentation occurs and the products are primarily oligomers in the tetramer‐to‐decamer range; therefore, the reaction is quite well suited to the study of reaction variables. It is found that the composition of the reaction product is almost independent of the degree of conversion, but that increasing the cocatalyst concentration tends to shift the molecular weight maximum to somewhat higher values. Changing the cocatalyst from methanol to acetic acid makes little difference, and the amount of fragmentation seems to be unaffected by the amount or kind of cocatalyst.
Thermal degradation of polystyrene: Effect of end groups derived from azobisisobutyronitrile
Authors: Cascaval C. N. , Straus S. , Brown D. W. , Florin R. E. 
Published: June 2010

AbstractPolystyrenes containing end groups derived from azobisisobutyronitrile (AIBN) were subjected to thermal degradation at 280–350°C and the rates of volatilization compared with those of thermally and anionically prepared polystyrene. At 330–350°C the degradation of the AIBN polymer resembled that of the thermal polymer and differed from that of the anionic one. At 280–320°C its behavior was complex; infrared analysis of the degraded polymer and pyrolysis gas chromatography results suggest weak bond involvement in some cases.
Photodegradation of colored polyethylene films
Authors: Mlinac M. , Rolich J. , Bravar M. 
Published: June 2010

AbstractThe changes of mechanical, physical, and chemical properties of colored low‐density polyethylene films under ultraviolet light were investigated. The study was performed using commercially manufactured colored pigments: Cadmium Yellow, CdS/ZnS; Ultramarine Blue, Na7Al6‐Si6O24S3; Copper Phtalocyanine Green, C32H2N8Cl14Cu, and Chrome Orange, PbCrO4.PbO. Two series of colored film samples were subjected to artificial aging in a weatherometer. The first series contained no ultraviolet absorber and the second one contained substituted 2(2′‐hydroxyphenyl)‐benzotriazole (Tinuvin 328).It was found that the extent of film deterioration depends on the nature of the pigment utilized. Two types of pigment influence on the rate of film properties changes were observed. When using Cadmium Yellow an enhanced process of polyethylene degradation was noted, while, in contrast to this a delay in aging of films was observed with Chrome Orange, Copper Phtalocyanine, and Ultramarine Blue.
New aspects in the activity of nitrogen‐containing antioxidants
Authors: Schulz Manfred , Wegwart Herbert , Stampehl Gundula , Riediger Werner 
Published: June 2010

AbstractThe antioxidative efficiency of amino‐methylated indoles and aminopyrazoles was examined by tetraline oxidation. Product studies were carried out. From the key intermediates isolated, conclusions capable of generalization on the mode of action as inhibitors of the compounds investigated were drawn. On this basis, the synthesis of more effective antioxidants was possible.Tertiary amines of the general structure NCCCX are antioxidants when a) they can be easily transformed to N oxides by alkylhydroperoxides, and b) when the N oxides decompose readily yielding α, β‐unsaturated carbonyl compounds, and dialkylhydroxylamines and dialkyl nitroxyl radicals, respectively.Aminopyrazoles act as chain‐breaking antioxidants in a multistep reaction. Pyrazolyl radicals and aminyl radicals are formed as is indicated by the subsequent products. Stable dihydrophenacines are isolated from the inhibited tetraline oxidation by aminopyrazoles. Evidence is presented that a rapid isomerization of pyrazole radicals yields aminyl radicals as precursors of dehydrophenacine.
Microindentation hardness of oriented chain‐extended polyethylene
Authors: Baltá‐Calleja F. J. , Bassett D. C. 
Published: June 2010

AbstractThe Knopp and Vickers microindentation hardnesses of oriented chain‐extended polyethylene (cold‐drawn, then hydrostatically annealed at 5·35 kbar) have been measured to establish correlations with some of the morphological features previously investigated (lamellar thickness, orientation). The irreversible deformation increases with time under load and tends towards a characteristic limiting value for each annealing temperature. This limiting value of microhardness is an increasing function of annealing temperature, TA, and consequently of chain extension, 1. A conspicuous feature of the investigated oriented polyethylene samples is the clear anisotropy exhibited by the indentation pattern. The Vickers microhardness is a maximum when the indenter diagonal lies parallel to the fiber direction and minimum when normal to it. The opposite occurs for the Knoop case. This contrary behavior is due to the shape difference between the two indenters coupled with the high anisotropy of the material. This behavior supports morphological experiments and is a further illustration of the value of this technique in polymer textural studies.
Observations of trimodal crystal texture in polypropylene blended with nylon 11
Authors: Seth K. K. , Kempster C. J. E. 
Published: June 2010

AbstractX‐ray diffraction techniques, optical microscopy, and scanning electron microscopy have been used to study a series of melt‐spun bi‐constituent fibers containing isotactic polypropylene and nylon 11. The addition of small amounts of nylon 11 produces bimodal crystal texture in polypropylene with most crystallites having either their c‐axes or a‐axes oriented nearly parallel to the fiber axis. In blends containing about 50% nylon 11 a third polypropylene crystallite orientation is observed in which the [101] directions are oriented nearly parallel to the fiber axis. The polypropylene chain axes make an angle of about 50° to the fiber axis, and an additional set of layer lines is produced. In blends containing more than 50% nylon 11, most of the polypropylene crystallites adopt the third orientation. It is suggested that this third orientation of polypropylene crystallites is the result of epitaxy on portions of nylon 11 fold surface at the interface between the two components.
A current account of chain extension, fibrous crystallization, and fiber formation
Authors: Keller A. 
Published: June 2010

AbstractA broad, rather personal survey is presented on chain alignment and fibrous crystallization. First, attention is drawn to the fact that fibrous crystal entities can be of fundamentally different origin and certain methods for their identification are proposed. Following this, the largest part of the survey is concerned with fibrous crystallization from pre‐extended molecules. As a first step, methods for extending chains and for observing their extension are outlined. Elongational flow is receiving special attention: conditions by which it can lead to ultrahigh chain extension are briefly defined as high‐lighted both by a priori considerations and by most recent experiments, methods of realizing these conditions being indicated both in solutions and melts. Following this, attention is given to the mode of crystallization of extended chains and to the structures which arise. Amongst the many factors involved, the part played by the local flow field arising from the presence of the growing crystal entity within the general flow field is outlined, leading up to the basic mechanism by which fibrous crystals grow. It is shown how the recognition of these principles can be utilized for producing crystalline fibers. The unusual thermal and mechanical properties of the products with special emphasis on melting behavior and modulus are indicated. A short section is devoted to the achievement of very high chain extensions by means of deforming material crystalline to begin with and the resulting products are contrasted with those obtained by means of crystallizing pre‐extended chains as regards thermal and mechanical behavior.
Small‐angle light scattering (SALS) from helically twisted fibers
Authors: Gałeski A. , Pakuła T. , Kryszewski M. 
Published: June 2010

AbstractThe small‐angle light scattering patterns for fibers with helical orientation were evaluated. The experimental results of the light scattering were obtained from two kinds of helically twisted fibers and compared with the theoretical prediction considering the refraction correction. The agreement with the theory was satisfactory.
Method of direct registration of the binary function of particles distributed in volume
Authors: Poltoratzkiy B. F. , Sachkov K. N. 
Published: June 2010

AbstractA new method of registering the full binary distribution function of light‐scattering particles in volume is suggested. This method is based on a statistic analysis of space distribution for the intensity of coherent light scattering by particles in a volume. Theory and block diagrams illustrating the method are presented.
Influence of electric reorientation of molecules on the rotational broadening of the spectra of rayleigh light scattering by small macromolecules in solution
Authors: Alexiewicz W. , Buchert J. , Kielich S. 
Published: June 2010

AbstractSpectral line broadening of Rayleigh scattered light in the presence of weak molecular reorientation is calculated by Racah algebra using the Debye rotational diffusion approximation. It is shown that if the incident beam is linearly polarized, the polarized and depolarized scattered components are superpositions of the well known Lorentzian, typical for free rotational diffusion, and non‐Lorentzian lines with intensities dependent on the reorientation parameters of the permanent and induced electric dipoles of the macromolecules. The measurement of electrically induced changes in peak intensity is proposed as a method for determining the sign of the optical polarizability anisotropy.
Adsorption of macromolecules on the solid adsorbents surfaces
Authors: Eltekov Yu. A. , Kiselev A. V. 
Published: June 2010

AbstractA study has been made of polymer adsorption from dilute solutions by porous and nonporous adsorbents of different natures. Adsorption of linear polymer–elastomers from dilute solutions can be approximately described by the equation of monolayer adsorption. The positive adsorption of polymers on oxide adsorbents is observed in those cases where macromolecules have polar functional groups while the solvent molecules are nonpolar. Use of strongly polar solvents (alcohols and ketones), substantially decreases the adsorption of polymers on these adsorbents and, in some cases, leads to negative adsorption values. Chemical modification of the surface of oxide adsorbents also strongly affects the adsorption values, resulting in a change of their sign. In the case of porous adsorbents, the value of adsorption of macromolecules depends on the pore sizes; the negative one being due to a steric effect. It was possible, using a set of nonswelling adsorbents with a narrow pore‐size distribution, to estimate the molecular mass distribution for a polydisperse polymer.
X‐ray and optical studies of the morphology of polymer blends
Authors: Stein R. S. , Khambatta F. B. , Warner F. P. , Russell T. , Escala A. , Balizer E. 
Published: June 2010

AbstractBlends may be made of pairs of polymers where neither, one, or both components are crystalline. The state of compatibility for such blends may be deduced by x‐ray and light scattering. A survey of recent studies in this laboratory of several binary blends of crystalline and amorphous polymers is presented.
Developments in radical polymerization
Authors: Vogl O. 
Published: June 2010

AbstractDevelopments in the field of radical polymerization including co‐ and graft polymerization are evaluated from a personal viewpoint. A number of important advances have been made in the last few years which present the opportunity of opening new ways for further scientific and technological progress. Also included in this critical evaluation of developments in co‐ and graft polymerization primarily by radical initiators is work that is peripheral to the subject but constitutes possible important new directions of development.
Synthesis and characterization of rigid‐chain polyacenaphthylene
Authors: Chen Chi‐Yu , Piirma Irja 
Published: June 2010

AbstractRigid‐chain polyacenaphthylene (PAcN) was synthesized by a novel emulsion polymerization method that besides water and the sodium oleate emulsifier consisted of a water‐soluble initiator, K2S2O8, and the water‐insoluble (at the polymerization temperature 50°), crystalline monomer acenaphthylene. The molecular weight of the emulsion PAcN was 150, 000 by gel permeation chromatography (gpc). With the exception of a C13nuclear magnetic resonance study, the PAcN was characterized in the bulk state by infrared spectroscopy and x‐ray and electron diffraction. The C13nmr spectrum in solution suggests a macromolecular association. The infrared spectra indicate that the PAcN can be either paracrystalline or amorphous. An amorphous infrared band at 670 cm−1was identified. The emulsion PAcN is predominantly threo‐disyndiotactic, and it is possible, therefore, to have a mesophase of nematic type in the bulk state. The paracrystallinity or ordered structure of PAcN is supported by wide‐angle x‐ray and electron diffraction patterns.
Nematic polymers
Authors: Pincus P. , De Gennes P. G. 
Published: June 2010

AbstractWe present a primitive model that describes a cooperative helix‐coil liquid–crystal phase transition. Consider a solution of macromolecules that individually undergo a helix‐coil “transition” as a function of some external parameter such as temperature or pH. At some given value of the parameter, the chain is composed of a statistical distribution of rigid (helical) segments and flexible coiled segments. We then suppose that there exists an intermolecular Maier‐Saupe type of quadrupole‐quadrupole interaction between the rigid sections that derives from excluded volume and van der Waals forces. In terms of a mean‐field approximation, we investigate the possible phase transitions as a function of polymer concentration. In particular, we show that the intermolecular coupling may lead to a first‐order transition in which the macromolecules make a transition from a nearly coiled to a nearly rigid conformation accompanied by the simultaneous development of a long‐range nematic type of liquid‐crystalline orientational order.
Microscopic determination of the penetration of proteins and polysaccharides into poly(hydroxyethyl methacrylate) and similar hydrogels
Authors: Refojo Miguel F. , Leong Fee‐Lai 
Published: June 2010

AbstractUltraviolet and light microscopy were used to measure the depth of penetration of fluoresce‐in‐labeled dextrans, serum albumin, and lysozyme into hydrogels. Proteins were visualized by a staining technique. Hydroxyethyl methacrylate was bulk polymerized (PHEMA, 37.7% H2O) and solution polymerized (PHEMA, 41.05–42.90% H2O); poly(glyceryl methacrylate) was solution polymerized (PGMA, 76.0–84.8% H2O); and poly(GMA‐co‐methyl methacrylate) was bulk polymerized [P(GMA/MMA), 41.5% H2O]. Dextrans of up to 150,000 mol wt and lysozyme penetrated PHEMA hydrogels; dextrans, but not proteins, penetrated P(GMA/MMA) hydrogels. Albumin penetrated only in the higher hydrated PGMA hydrogels. The porosity of PHEMA hydrogels is at least as large as 30 Å (the smaller axis of lysozyme); the porosity of P(GMA/MMA) hydrogels is at least 19 Å (the thickness of the rodlike dextran molecules of 150,000 mol wt). The PGMA hydrogels have a porosity of at least 50 Å, which is the size of the smallest axis of serum albumin.