bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photochromic polymers
Authors: Vandewijer P. H. , Smets G. 
Published: June 2010

AbstractPhotochromic spiropyran copolymers have been prepared by radical copolymerization of 5‐methacrylamino‐3,3′‐diméthyl‐6′‐nitrobenzthiazo‐linospiropyran (R is CH2=C(Me)‐CO‐NH) with different vinyl monomers, as methyl methacrylate, methacrylonitrile, styrene, and 2‐vinylnaphthalene. Their solution behavior has been examined in different solvents and compared to that of the corresponding 5‐isobutyraminoderivatives (R is i‐C3H7‐CO‐NH). magnified image In a strong solvating medium the copolymers display a strong negative solvatochromism and behave similarly to the model substance; their decoloration reaction kinetics follow a first‐order relationship. The decoloration activation energy in DMF varies from 24.9 to 25.6 for the different copolymers instead of 22.1 for the model. In less polar solvents, the λmax of the copolymers show a large hypsochromic shift when compared to the model, while the decoloration reactions deviate strongly from first‐order kinetics. These deviations are interpreted by assuming the existence in the copolymers of two photocolored isomeric components, in slow equilibrium with each other, and with optical densities a and b and agree with following equation where the optical density can be related to the time of decoloration t.

The ratio a/b i s equal to 0.57, 2.00, and 2.06 in acetone, dichloromethane, and tetrahydrofuran, respectively. It is assumed that the steric hindrance resulting from the macromolecular environment raises the potential barriers between these different stereoisomers. On addition of a polar nonsolvent as t‐butanol, first‐order kinetics are, however, restored up to a degree of conversion of 60%. The rate of decoloration of methyl methacrylate copolymers decreases with increasing spiran content. Finally, it was observed that an increase of the solution viscosity also provokes a deviation from first‐order kinetics.
Reactivities and structural aspects in the cationic polymerization of mono‐ and diolefinic norbornanes
Authors: Kennedy J. P. , Makowski H. S. 
Published: June 2010

AbstractTo evaluate the various factors operative in carbonium ion polymerization of ring structures, in particular monoolefinic and diolefinic norbornane derivatives, the polymerization of select monomers was effected: 2‐methylene norbornane, 2‐methylene‐5‐norbornene, norbornene, 2‐vinyl‐5‐norbornene, 2‐isopropenyl‐5‐norbornene, 2,5‐norbornadiene, 2‐vinyl norbornane, and 2‐isopropenyl norbornane. The relative reactivities of these monomers and the structures of the polymers produced therefrom were rationalized on the basis of well‐documented organic‐chemical principles. Steric compression during propagation was considered to be a critical determinant in the polymerizability of methylene cycloalkanes. The relative polymerizabilities of cycloalkenes were explained on the basis of the ability of the first‐formed secondary cation to undergo a hydride shift to a nonpropagating tertiary cation. Similarly, the structures of polymers derived from vinyl cycloalkanes were explained on the basis of hydride shifts and steric compression during propagation.
The oxidative coupling of 2,6‐disubstituted phenols with PbO2 and other metal oxides
Authors: Van Dort H. M. , De Jonge C. R. H. I. , Mijs W. J. 
Published: June 2010

AbstractThe main product in the oxidative coupling of 2,6‐dimethyl phenol with PbO2 and other metal oxides is poly‐2,6‐dimethyl phenylene oxide (Mn up to 20,000). The influence of the temperature, the solvent, and the addition of small amounts of various substances on the course of the reactions is discussed. The addition of an amine to the reaction mixture suppresses the diphenoquinone formation, and polymers with much higher molecular weights may be obtained. Infrared and NMR endgroup analyses show that the polymers prepared with PbO2 and in the absence of amines are branched. On the addition of increasing amounts of amines to the reaction mixtures the degree of branching gradually decreases. Mechanisms for the branching reaction are suggested. The effect of soluble onium salts, such as trimethylcetylammonium bromide, on the course of the oxidative coupling is mentioned (slow reactions giving polymers with high molecular weights). Aromatic polyethers are also obtained in the metal oxide oxidations of 2,6‐disubstituted phenols with bulky substituents, such as: 2,6‐diethyl phenol, 2,6‐diisopropyl phenol, and 2,6‐dimethoxy phenol. Some properties of the polymers are given. There are indications that the reactions go by way of metal phenolates.
Ueber einige makromolekulare Halbleiter mit Porphyrazinstruktur
Authors: Manecke G. , Woehrle D. , Kossmehl G. 
Published: June 2010

AbstractPolymers with a structure similar to phthalocyanine were made by melting of tetracyanothiophene (I), tetracyanofuran (II), octacyano‐P.P.P‐triphenylphospholidine (III), tetramethyl‐bis(maleonitriledithiolato)cuprate (IVa), and copper bis(maleonitriledithiolato)cuprate (IVb) with copper acetylacetonate and with other metal acetylacetonates in different molar ratios and with o‐phthalodinitrile (V). The conductivities at a pressure of 1,500 kp‐cm.−2 were in the range of 5.7 × 10−5 to 10−14 ohm−1 cm.−1. The conductivities decreased with decreasing aromatic character of the starting nitriles. In some cases of polychelates with two different incorporated metals higher conductivities were found than were expected from the two unimetallated polychelates. For various metal polychelates of (I) there seems to be a relationship between the conductivities and the ionization potentials and the ionic radii of the metals. Measurements of the thermal EMF showed p‐conduction. Seebeck coefficients were independent of the temperature for the polychelates made from (I) and (II) and were dependent on the temperature for the polychelates made from (III). A certain polychelate made from (III) had a thermal EMF of 40 mv. for ΔT × 30°. Polymers with a structure similar to tetraazadiarylene‐diisoindolenine were obtained by fusing of (I) with p‐phenylenediamine, and of (I), (IVa), (IVb), and nickel bis(maleonitriledithiolato)cuprate (IVc) with 2,6‐diaminopyridine and by melting of 2,5‐diamino‐3,4‐dicyanothiophene with or without CuCl2. The structure was proved by elementary analysis and by IR spectroscopy. The conductivities were in the range of 7.1 × 10−3 to 1.0 × 10−9 ohm−1 cm.−1. The polymers made from (IVb) and (IVc) showed smaller conductivities than did those from (IVb) and (IVc).
Viscosity of chain polymers in solution
Authors: Isihara A. 
Published: June 2010

AbstractA theory is developed for the intrinsic viscosity of chain molecules in solution. The molecules are assumed to be composed of many repeating units called segments, which are distributed spherically around the center of each molecule. An integral equation similar to, yet different from, that of Kirkwood and Riseman is set up. This equation does not require the replacement of the Oseen hydrodynamical interaction tensor by its diagonal element and yields a new viscosity formula. This formula is rather general and is characterized by the Fourier transform of the segment distribution function and the eigenvalue λ(k) of the Oseen tensor expressed in momentum space. In the absence of hydrodynamical interactions between segments the formula is reduced to the Debye formula for the Staudinger empirical law. In the presence of interactions the eigenvalue λ(0) characterizes the viscosity. This eigenvalue is related to the average characteristic length of a chain molecule, through which the molecular‐weight dependence of the viscosity comes in.
The effect of solvent on the unperturbed dimensions of polystyrene
Authors: Cowie J. M. G. 
Published: June 2010

AbstractThe unperturbed root‐mean‐square radius of gyration of a polystyrene sample was measured in ten critical consolute mixtures encompassing solubility parameters ranging from 8.1 to 11.4 (cal./cm.3)1/2. The values of the intrinsic viscosity and coil size were found to reach a maximum in the vicinity of δp, the polymer solubility parameter. Preferential adsorption of the solvent component in the mixture, by polystyrene, was observed in each of the ternary systems examined. The variations in coil size and intrinsic viscosity were found to be mainly a function of solvent polarity and were not caused primarily by preferential adsorption, which was comparatively small in most of the mixtures.
The mechanism of polymer permeation through polymer gel membranes
Authors: Meyerhoff G. , Stannett V. 
Published: June 2010

AbstractPolymer gels are capable of producing separation effects on polymers. Applications for fractionation and for osmotic measurements are possible. Investigations are reported concerning the separation properties of polystyrene layers grafted onto a supporting cellulose basis. The permeation for pure solvents and the separating molecular limit for different solvents are tested. Their size depends uniquely on the interaction between the grafted polystyrene and the solvent.
Organized polymerization of vinyl pyridinium salts
Authors: Kabanov V. A. , Patrikeeva T. I. , Kargina O. V. , Kargin V. A. 
Published: June 2010

AbstractThe study of the spontaneous polymerization of quaternary vinyl pyridinium salts in concentrated aqueous solutions showed that the process occurred by the specific ionic mechanism. The results of kinetic measurements made for 1,2‐dimethyl‐5‐vinylpyridinium methyl sulfate are interpreted in terms of chain propagation in aggregates of regular monomeric salts existing in solutions at concentrations close to saturation. The aggregates of activated monomeric molecules also exist in dilute solutions when the formation of salts from vinylpyridine and polymeric organic acids takes place. In this case the polyacid macromolecules act as activating polymeric “matrices”.
Polysiloxane‐s‐triazinyl ethers
Authors: Bettelheim Frederick A. , D'Amelia Ronald 
Published: June 2010

AbstractPolysiloxane‐s‐triazinyl ethers were prepared by condensing silanediols in dimethylformamide with cyanuric chloride in dioxane. Dry or aqueous base was used as catalyst and dimethylsulfoxide as promoter. Some structural and physical properties of these compounds are reported. The inclusion of the triazine ring in the silicones provides additional thermal stability with polyphenylsiloxane chains but only slight thermal improvement with bis(p‐chlorophenyl) siloxane chains.
Graft copolymerization onto proteins by the ceric ion method. II. Grafting onto bovine serum albumin
Authors: Iwakura Yoshio , Imai Yohji 
Published: June 2010

AbstractGraft copolymerization of methyl methacrylate onto bovine serum albumin (BSA), trypsin, and α‐amylase was carried out by the ceric ion method. The grafted polymer chains were separated by selective hydrolysis of the backbone proteins with hydrochloric acid. The number of grafting sites were 0.02 to 0.3 moles/mole. Graftings were greatly affected by denaturation of the protein molecule. It is concluded that the grafting onto BSA is likely to occur at cysteine and cystine residues.
Volume–temperature relation of epoxy resin–acid anhydride mixtures with different degrees of crosslinking
Authors: Shimazaki Akio 
Published: June 2010

AbstractVolume‐temperature relations of six kinds of epoxy resin‐acid anhydride composite and different curing times are discussed on the basis of free‐volume and occupied‐volume concepts. The specific volume Va at a fixed temperature above Tg decreases linearly with increasing Tg, but the specific volume Vb below Tg increases linearly. The specific volume Vg at Tg increases linearly with increasing Tg. The relation between Tg and log crosslinkage is linear except in the final stage of the curing process. The slope B of the Vg‐Tg relation is obtained from the iso‐free‐volume theory of glass‐transition phenomena as B = Voαb(1 – ΔVo/Vf · Vf/Vo · αa – αb/αb), where Vo is the occupied volume, Vf the free volume, αa – αb the thermal expansion coefficient of free volume, αb the thermal expansion coefficient of occupied volume; Vo is the sum of the two components Vo and Vo, where Vo is the occupied volume in the strict sense and ve is the empty volume into which polymer chains cannot flow. The equation predicts qualitatively the observed value of B.
Optical rotatory dispersion of synthetic polymer: Conformational aspects of N‐substituted poly‐2‐ethylethylenimine
Authors: Tsuboyama Sei , Yanagita Masaya 
Published: June 2010

AbstractN‐Benzoylated poly‐2‐ethylethylenimines of different stereoregularities were prepared, and their optical rotatory dispersions (ORD) were measured in various solvents. The ORD behavior of the regular polymer in cyclic ethers was anomalous, and that of the irregular one changed to a simple dispersion. The result and general optical rotatory properties suggest that the regular polymer exists in a specific conformation, perhaps as a helix, in the solvents.
The formation reaction of a phenylmethylene polysulfone
Authors: Tokura Niichiro , Nagai Toshikazu , Shirota Yasuhiko 
Published: June 2010

AbstractPolysulfones with a unit of magnified image have not yet been prepared. By the reaction of benzylsulfonyl halide with phenyllithium, oligomers with a unit of phenylmethylene sulfone magnified image were prepared, which include a disulfone, a trisulfone, and polysulfones with molecular weights of 850–970. The disulfone and the trisulfone were identified as α‐benzylsulfonyl‐α‐benzenesulfonyl toluene and α‐benzylsulfonyl‐α′‐benzenesulfonyl dibenzyl sulfone respectively, and the polysulfones were characterized as phenylmethylene polysulfones magnified image on the basis of the infrared and NMR spectra, elemental analysis, and the pyrolysis results. It has been observed that in ether solvent polysulfones were formed only at a low temperature (−70°C.), together with the trisulfone and the disulfone. However, in THF solvent polysulfones formed exclusively. Some factors exerting an influence on the formation of polysulfones and their formation mechanism are discussed.
An X‐ray study of cellulose triacetate
Authors: Watanabe Sadayoshi , Takai Mitsuo , Hayashi Jisuke 
Published: June 2010

AbstractCellulose triacetate I is yielded from cellulose II of mercerized cellulose and rayons in heterogeneous acetylation with lower swelling pretreatment. Both cellulose triacetates I and II with highly ordered structure substantially are converted into cellulose II on saponification. It is possible to obtain transformation of triacetate I to triacetate II without any dissolving process by a comparatively simple treatment with superheated steam. These three points are discussed.
Comparative chemical reactions between α,β‐unsaturated polyesters and monomeric maleic and fumaric esters. I. Nucleophilic addition
Authors: Lee Sung Ki 
Published: June 2010

AbstractThe noncatalytic nucleophilic addition of ammonia and amines with α,β‐unsaturated polyesters at temperatures between 20 and 80°C. was investigated. The mode of reaction is shown to be to a large degree dependent upon the nature of the solvent used. In a protonic solvent poly(hexamethylene glycol maleate) readily reacts with primary or secondary amines to give a normal 1,4 addition product as final product. In a nonprotonic solvent it undergoes rapid isomerization to poly(hexamethylene glycol fumarate). The behavior of these α,β‐unsaturated polyesters is compared with that of monomeric, unsaturated esters, such as dialkyl maleate and dialkyl fumarate. A reaction mechanism is suggested to account for the products of reaction, and the possible driving forces of the reaction is discussed. The comparative rates of reaction between polymeric and monomeric compounds were conveniently followed by using NMR, infrared, and polarographic methods.
The oxidation of ethylene–propylene copolymers with hexavalent chromium compounds
Authors: Burgert Bill E. 
Published: June 2010

AbstractThe oxidation of solutions of ethylene–propylene copolymers with chromic acid, chromyl chloride, and t‐butyl chromate has been studied. The efficacy of these reagents in producing crosslinking sites has been determined by curing with toluene diisocyanate. The presence of hydroxyl and carbonyl groups has been demonstrated by the preparation of soluble derivatives of the oxidized copolymers.
A computer program for the visualization of stereoregular polymers
Authors: Price Fraser P. 
Published: June 2010

AbstractThis paper describes a computer program that is useful in the elucidation and visualization of particular stereoregular polymer chains. The input is the fractions of isotactic, syndiotactic, and heterotactic triplets in a real polymer as determined by some technique such as NMR. The program calculates a matrix of conditional transition probabilities from these fractions. This matrix in conjunction with a random‐number generator is used with Monte Carlo techniques to calculate a specific sequence of 0's and 1's. The sequence contains 101 elements. This is the generated polymer chain. The number of various kinds of doublet, triplet, etc., is then counted for this particular generated chain, and compared with that calculated from the matrix for the chain of infinite length. Comparisons among these sets of figures show that the generated polymer chains are usually quite typical of the infinite chain.The application of NMR techniques to the determination of the relative numbers of isotactic, heterotactic, and syndiotactic triplets in synthetic polymers was pioneered by Bovey (1) several years ago. The data thus obtained can be used in a straightforward manner to calculate various average properties of the polymer chain. Although these average properties may be used to describe the polymer, frequently it is difficult to visualize exactly what a typical polymer chain might look like from a stereoregularity point of view. This paper describes a computer program that calculates various sequence averages for an infinite polymer chain and that generates by Monte Carlo techniques a polymer chain typical of the NMR data. In addition the program, by calculating various sequence averages for the generated polymer chain, permits evaluation of just how representative the generated polymer is.
Polymer reactors and molecular weight distribution. Part V. Free‐radical polymerization in a transient stirred‐tank reactor train
Authors: Hui A. W. , Hamielec A. E. 
Published: June 2010

AbstractThe transient behavior of both batch and continuous stirred‐tank reactors for free‐radical polymerization of styrene have been studied. For the batch reactor a high‐conversion model was developed, based on experimental investigations measuring the conversion and molecular weight distribution. Significant improvement over the low‐conversion model was obtained when the viscosity or gel effect was accounted for by allowing the termination constant and catalyst efficiency to vary with viscosity. A transient model was also developed for a continuous stirredtank reactor based on batch reactor kinetics. This model was employed in the simulation of a system of stirred‐tank reactors operating under transient conditions.
Morphology and mechanical behavior of block polymers
Authors: Beecher James F. , Marker L. , Bradford R. D. , Aggarwal S. L. 
Published: June 2010

AbstractThe morphology of solution cast films of butadiene and styrene block polymers in both stretched and unstretched state has been studied by electron microscopy, and has been related to the mechanical behavior of these materials. These micrographs confirm the indications from dynamic properties that this material consists of a two‐phase system in which the relationship between the phases is sensitive to the solvent system used in casting. Although the basic morphological unit is a polystyrene sphere of 100 Å diameter dispersed in a matrix of polybutadiene, the interaction between spheres is complex. These spheres are more deformable than would be predicted from their glass transition temperature. The dynamic mechanical properties, stress‐strain properties, and stress relaxation properties of block polymers of styrene and dienes can be explained in terms of the morphology and changes of morphology on stretching in the electron microscope.
The stress‐strain‐birefringence properties of styrene‐butadiene block copolymers
Authors: Fischer E. , Henderson J. F. 
Published: June 2010

AbstractThe stress‐strain‐optical properties of three elastomeric styrene‐butadiene block copolymers containing 31, 40, and 49 wt‐% styrene were studied as a function of temperature. The mechanical and the optical properties indicate that these materials are two‐phase systems in which the polybutadiene chains form an elastomeric phase and the polystyrene a glassy phase with the latter providing physical crosslinks. Birefringence measurements indicate that the decrease in modulus and strength of these materials is associated with a decrease in the concentration of elastically effective network chains. The independence of the stressoptical coefficient on temperature suggests that the decrease in concentration of elastically effective chains is not due to the onset of rubber‐like behavior of flow within the polystyrene regions themselves, at least for temperatures below about 70°C. Rather, the decrease seems to be associated with the increased mobility of the polybutadiene chains at higher temperatures which also leads to an increase in the rate of stress relaxation. Birefringence measured during extension and retraction showed that the stress‐strain hysteresis is due to restricted mobility of the polybutadiene chain segments rather than to permanent viscous flow or to a change in the effective network structure of the block copolymers. The ultimate properties of these rubbers correlated well with the effective network structure in undeformed samples.
Kinetics and mechanism of the emulsion polymerization of ethylene
Authors: Stryker H. K. , Mantell G. J. , Helin A. F. 
Published: June 2010

AbstractDuring the emulsion polymerization of ethylene the solubility of the monomer at 85°C and 4500 psig is 0.3–0.6 mol/1 in the aqueous phase and about 5 mol/1 in the monomer‐polymer particle. Hence, ethylene, like vinyl acetate, can be considered a water‐soluble monomer. The rate of polymer formation is proportional to the square root of the initiator concentration. The polymers contain a large amount of low molecular weight polymer that contributes to their characteristic lack of elongation at break. They also contain emulsifier covalently bound in the polymer by a chain‐transfer reaction. Because chain transfer occurs with emulsifier adsorbed on the particle surface and retards the rate of polymer formation, the molecular weight of the polymer is proportional to the particle diameter and the rate of polymer formation is inversely proportional to the emulsifier concentration. Based on similarities in dependence of density and branching on temperature, the propagation step in emulsion polymerization resembles that in the high pressure synthesis of polyethylene. In the absence of chain transfer, however, the structure of emulsion polyethylene becomes complex.