bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the nature and properties of cellulose acetate and poly(vinyl alcohol) gels
Authors: Glikman S. A. , Roth L. A. , Khomutov L. I. , Gubenkova E. N. , Feigelson I. I. 
Published: June 2010

AbstractDilatometric, rheological, and some optical (spectrography, birefringence, light scattering) investigation methods were adopted to study gelation processes in acetyl cellulose (AC), poly(vinyl alcohol) (PVA), and iodopoly(vinyl alcohol) (IPVA) solutions in different solvents. The influence of the molecular and chemical heterogeneity of these polymers upon the gelation temperature and mechanical properties of gels is ascertained. The jumps in the volume versus temperature dependence ΔV(T) of PVA fraction solutions were discovered. The greater the molecular weight of polymer fractions the higher is the temperature of these jumps. It is established that diluted AC solutions in benzyl alcohol as well as its concentrated acetone solutions are nonhomogeneous thixotropic systems with long relaxation times. The results of investigation have been interpreted by means of the conception about gelation as the separation of fractions, which have become insoluble (under changed thermodynamic conditions), from homogeneous polymer solution. These fractions form a second amorphous phase, either as the single whole network, enveloping the solution of the other fractions by its network (gel), or as discrete aggregates (gel suspension). The structure variants, for example, partial crystallization, present the consecutive stages of a thermodynamic transition of a true solution into a non‐homogeneous colloid system.
Stress‐strain‐time relation of poly(n‐alkyl methacrylates) in rubbery state
Authors: Hata Toshio , Nose Takuhei 
Published: June 2010

AbstractMeasurements of stress‐relaxation under various extension ratios and stress–strain under various rates of extension are made for polymethyl, ethyl, n‐propyl, and n‐butyl methacrylates in their rubber regions. The time–temperature superposition at the same extension ratios is possible, but the larger the extension ratio, the faster the stress relaxes. Assuming that polymer chain length is approximately distributed along a Gaussian curve and that the relaxation spectrum shifts along log τ axis by log aα without changing its shape with extension, we can express the results of stress–relaxation for different extension ratios and temperatures by the following equation:

where S is the stress per the initial cross‐section, Ts is the reference temperature, aT is the time–temperature shift factor, aα is the time–extension ratio shift factor, and H(τ) is the relaxation spectrum. For stress–strain under constant rate extension, the time–extension ratio superposition is also possible with the different shift factor aαs, which is related to the aα through the equation a = (α ‐ 1)/ ∫1α dα/aα. The calculated a agrees satisfactorily with the observed. The dependence of aα and aT on the extension ratio is derived from the free volume theory, which interprets experimental results comparatively well.
Specificity in hydrolysis of the A and B chains of the oxidized insulin by carboxylic resins
Authors: Glikina M. V. , Gudkin L. R. , Makhortych S. V. , Samsonov G. V. , Dinaburg V. A. , Genender K. M. 
Published: June 2010

AbstractThe catalytic activity and the specific action of nine carboxylic ion‐exchange resins of various structure has been investigated on the example of a hydrolysis of two individual substrates: A and B chains of oxidized insulin. It has been shown that nearly all these catalysts hydrolyze both substrates. A specific arrangement of the catalyst matrix to a given substrate is shown to be necessary for manifesting the catalytic capacity of the resin in intramolecular catalysis. A change in the catalyst structure, in the length of the chain, and the nature of the crosslinking agent strongly influence the hydrolyzing effect and depends on the structure of substrate. Variation of the catalysis with ionic force and pH of reaction mixture has been shown. The specific action of these catalysts has been determined and it has been shown that the first bond to be hydrolyzed is the one at the C‐end of cysteic acid or the next to it.
Über die Druckabhängigkeit der Glasigen Erstarrung von Hochpolymeren
Authors: Rehage G. , Breuer H. 
Published: June 2010

AbstractVitreous solidification is often considered to be a second‐order thermodynamic transition and a more or less satisfactory agreement is found between the thermodynamic parameters and the Ehrenfest equations (dP/dT)I = Δα/Δx; (dP/dT)II = ΔP/T · Δα. Measurements of volume retardation carried out by Goldbach and Rehage show that vitreous solidification is not a true transition. The question is if vitreous solidification at least formally can be treated as a thermodynamic transition. Measurements of specific isothermal compressibility and specific volume of amorphous polystyrene in the pressure range up to 10 kb and at temperatures of 100–250°C. carried out by the authors and calorimetric measurements of Koplin on the same polymer show that both Ehrenfest equations differ from experimental data by ca. 50%. The deviations are explained by considerable variation of specific volume with the path of the transformation in the glassy state which also had been measured. This variation with the path of transformation is due to the change of order within the material with increasing pressure along the freezing curve. The Ehrenfest equations are formally valid for a freezing process with the same inner order obtained at all pressures at the corresponding freezing temperature. The Ehrenfest equations can be combined by eliminating dP/dT but the relation obtained does not allow discrimination between a second order transition and the vitreous solidification. In this paper it has been shown that the vitreous solidification distinctly differs in both characteristics and formal treatment from a thermodynamic transition.
La Cristallisation des Systèmes Polymériques Mixtes. I. Copolymère Greffé de Polyacrylonitrile sur Polyéthylène
Authors: Job C. 
Published: June 2010

AbstractCrystallization and orientation phenomena have been examined in the case of graft copolymers, of which both components can cristallize but are incompatible. The polymer that was chosen was polyethylene (high or low density) onto which polyacrylonitrile was grafted using the pre‐ozonization method. The elimination of the homopolymers with selective solvents (xylene‐dimethylformamide) was controlled. Monocrystalline species were detected with the electron microscope after precipitation from a solution in a xylene‐dimethylformamide mixture. This mixture has a given composition for each type of graft copolymer. Electron diffraction shows a slight modification of the orthorhombic unit of the polyethylene. When the weakly grafted fractions are progressively eliminated this cocrystallization becomes more difficult and finally only rudimentary structures are obtained. A similar phenomenon is observed with recrystallized films. The orientation of fibers stretched in various conditions was followed by x‐rays. The simultaneous orientation of both polymers was observed in very precise conditions of temperature and medium (dimethylformamide). The possibility therefore must exist for the preparation of fibers combining in situ the complementary properties of both types of fibers.
Light scattering by water solutions of small particles subjected to an electric field
Authors: Stoylov S. P. 
Published: June 2010

AbstractAn extension of the theory of variation in the intensity of the scattered light by disperse systems subjected to an electric field is made, special attention being paid to saturation effects. Experimental data including saturation effects for a sample of TMV are presented. By fitting experimental results to theoretical curves calculated for different assumptions it is shown that agreement is obtained only when polydispersity of the sample is taken into account.
Neue Polyaryläther
Authors: Tokarzewska Maria 
Published: June 2010

AbstractNew species of polyether resins have been prepared by polycondensations of the ether of dichlormethylenediphenyl with some diphenols such as 4,4′‐dihydroxydiphenyldi‐methylmethane and 2,2′‐dihydroxydinaphthylmethane. The polycondensations have been carried out in the water and ethyl alcohol medium. The effects of the concentration of the reagents, of their molecular ratios, and the temperature on the properties of the resulting resins have been studied. Low molecular resins with low melting points have been obtained at low temperature of reaction and at low concentration of the reagents. Resins with improved properties have been prepared in an ethyl alcohol medium, with equimolar ratios of the reagents. An excess of NaOH in the reaction mixture has resulted in unmeltable crosslinked resins. The polyether structure of the resins has been confirmed by infrared spectra. The thermostability, according to Vicat, and the hardness according to Brinell, has been determined for the poly(aryl ethers).
Anomalous behavior of the resistivity of some donor‐acceptor complexes
Authors: Ottenberg A. , Browne M. E. 
Published: June 2010

AbstractThe d.c. resistivity has been determined as a function of pressure and electric field for the (1:1) donor‐acceptor complexes, (I) bis(tetrahydroindenyl)iron:tetracyanoethylene, (II) cobaltocene:tetracyanoethylene, and (III) p‐phenylenediamine:dinitrodurene. For I, II, and III the resistivity increases with increasing pressure in a reversible manner over the pressure range 260–2600 psi. For I and III the resistivity increases with increasing electric field; this behavior is essentially reversible except for the presence of a relaxation process. The phenomena are interpreted in terms of a mechanism involving slight reorientation of the molecular units in the crystal lattice similar to the processes responsible for ferroelectric behavior. The observation of these phenomena is assumed to have significant importance in terms of providing systems for the study of the effects of molecular arrangement in crystals upon the conduction mechanisms.
A New High Temperature Fiber, Its Properties and Performance
Authors: Weiss J. O. , Morgan H. S. , Lilyquist M. R. 
Published: June 2010

AbstractFibers of ordered aromatic copolyamides have been found to be exceptionally resistant to degradation at high temperatures. A typical member of this class of fibers has been selected for presentation to illustrate the high performance characteristics of these fibers. The selected polymer, containing ordered aromatic components with meta‐ and para‐benzanilide linkages, was spun into fibers from solution. The excellent heat stability of the fiber is demonstrated by its retention of strength at high temperatures and after prolonged exposures to elevated temperatures. Among other outstanding properties are its balance of tensile properties, resistance to hydrolysis and chemical degradation, high dielectric strength, and stability in ionizing radiation. Fabrics constructed from this fiber have good flexibility and abrasion resistance at elevated temperatures. The combination of high strength and durability at high temperatures should gain acceptance for this fiber in a variety of industrial and military applications including hot gas filter bags, belting, heat resistance clothing, electrical insulation in motors and transformers, and fabrics for parachute packs and harnesses.
The structural mechanics of fibers
Authors: Hearle J. W. S. 
Published: June 2010

AbstractThe “traditional” assumed structures of fibers, such as the fringed micelle and fringed fibril forms, regard the fiber as made up of a mixture of crystalline and noncrystalline regions. This view has been subject to considerable criticism in recent years, but it does, nevertheless, remain the most effective basis for describing many fiber properties. This paper attempts to show how the traditional forms can be modified, for instance by the introduction of chain folding, so that they are entirely compatible with current views on polymer crystallization. An overall picture of fiber structure is presented showing how various extreme forms–including continuous crystalline, paracrystalline, and amorphous structures as well as the two‐component forms–can be used to define the boundaries of a wide range of intermediate forms which are likely to occur in practice. The major decision in interpreting fiber properties is the choice of which extreme model–necessarily extreme in order to be susceptible to definition and analysis–is the most useful when studying a particular aspect of the behavior of a particular fiber. The mechanical properties, of wool, plant fibers, rayon, and synthetic fibers are discussed.
Spherulite structure, deformation morphology, and mechanical properties of isotactic polypropylene fibers
Authors: Samuels Robert J. 
Published: June 2010

AbstractThis study delineates the complex morphological‐deformation processes that occur during the spinning, fabrication, and testing of a series of drawn yarns as an integrated picture of mass movement on all morphological levels. The study involved the use of nine different experimental techniques, including small‐angle light scattering, small‐angle and wide‐angle x‐ray diffraction, micro x‐ray diffraction, birefringence, interference microscopy, and sonic‐modulus, density, and tensile measurements. A prerequisite of the study was a clarification of the morphological structure of three‐dimensional bulk isotactic polypropylene spherulites. The bulk spherulite was found to have a morphological structure (a axis parallel to the radius) consistent with the observed bulk morphology of fibers and films. Two‐dimensional Type III spherulites were similarly examined; their crystallites were found to be of the β form. As a result of the broad experimental approach to fiber‐deformation morphology used in this study the significance of the often ignored interspherulitic‐deformation mechanisms to fiber processes becomes apparent, the importance of the wide‐angle x‐ray, azimuthal intensity distribution for the characterization of inhomogeneous‐deformation processes is demonstrated, and an oriented‐microvoiding process is observed to be an important deformation mechanism.
Resolution and fractionation in gel permeation chromatography
Authors: Bly Donald D. 
Published: June 2010

AbstractFormulas are developed for describing resolution in gel permeation chromatography (GPC) in polymer analysis. Simple caluclations permit easy determination of the effect of variables on the resolution. Through the use of two characterized polymer samples the specific resolution Rs can be calculated. From the specific resolution the percent of fractionation between any two or more populations can be predicted or, conversely, a GPC curve can be analyzed for the component molecular weights and molecular weight distributions MWD and then the per cent fractionation between the components calculated. This is especially useful in preparatory scale separations and purifications. The principle of the constancy of width divided by polydispersity, W/d is developed and used to demonstrate a very simple method of determining the polydispersity of a sample.
Characterization of celluloses by gel permeation chromatography
Authors: Segal Leon 
Published: June 2010

AbstractGel permeation chromatography (GPC) applied to solutions of cellulose trinitrate in tetrahydrofuran (THF) has shown very promising results. Cellulose trinitrate was selected as the most suitable derivative for use in GPC because of several factors. The so‐called “solvent impurity” peak found in the chromatograms was shown to arise from dissolved air; the broadening of the peak observed with sample solutions was found to arise from other solvents and moisture. Indications are that THF does not rapidly degrade the dissolved trinitrate if the solution is stored with reasonable care. Nor did the dry trinitrate stored in a desiccator with exclusion of light degrade appreciably. Four cottons (one unpurified and three purified), two hardwood pulps, and two blends of hardwood and softwood were studied. Curves for the cottons indicated fairly broad, unimodal distributions. These were broadened considerably by acid hydrolysis. The degrees of polymerization (DP), although high, reflected the treatment applied. Wood pulps showed distributions broader than cotton, with much lower DP material, but also some material of even higher DP. A possible source of the latter is discussed. The distributions for the wood pulps were similar within the pairs but markedly different between the pairs. Some correlations were noted between GPC and pulp analytical data. Factors in the GPC technique itself, which may bear on the magnitude of the computed DP's, are pointed out and discussed.
Polyisonitriles. I. Original structure and possible rearrangement of poly(α‐phenylethylisonitrile)
Authors: Millich Frank , Sinclair Richard G. 
Published: June 2010

AbstractSeveral possible chemical structures for poly(α‐phenylethylisonitrile) are examined, and the structure is proposed for the polymer as it originally forms. The isolation of acetophenone from hydrolysates of the polymer suggests, although not conclusively, that the polymer may have undergone a tautomeric rearrangement to the structure Ultraviolet and infrared spectral data are cited as partial evidence of either of the proposed structures. The steric implications of the proposed structures are considered, and the probability that the polymerization and the presumed rearrangement are stereoregular chemical reactions is discussed. Debye‐Scherrer x‐ray patterns are presented for poly(α‐phenylethylisonitrile) and for poly(σ‐tolylisonitrile).
Studies in cyclocopolymerization. IV. Evidence of charge‐transfer complexes as intermediates in cyclocopolymerization of 1,4‐dienes with alkenes
Authors: Butler George B. , Joyce Kenneth C. 
Published: June 2010

AbstractCharge‐transfer complexes in solutions of comonomers such as divinyl ether and maleic anhydride have been identified by use of ultraviolet spectroscopy. Equilibrium constants and molar extinction coefficients were determined for several of these complexes. It appears reasonable that the cyclic units formed in these copolymers result from free‐radical initiation of the charge‐transfer complex, which preorients the comonomers into a conformation favorable for formation of copolymer in the observed comonomer ratio of 1:2. Copolymers prepared and studied were those of divinyl ether with N‐substituted maleimides having the following substituents on nitrogen: (a) hydrogen, (b) methyl, (c) ethyl, (d) n‐propyl, (e) isopropyl (f) n‐butyl, (g) isobutyl, (h) benzyl, (i) α‐naphthyl, (j) phenyl, (k) p‐methoxyphenyl. These copolymers were characterized by elemental analyses to establish the comonomer ratios and by viscosity measurements and in certain instances by determination of molecular weights by the vapor‐pressure osmometry method. The copolymer of divinyl ether and maleic anhydride has been found to be an effective antitumor agent by the Cancer Chemotherapy National Service Center, National Institutes of Health. Consequently, these copolymers were also submitted for evaluation in this program, and several have been found to possess favorable inhibiting action on tumor growth.
Thermal degradation of some vinyl polymers. I. Poly(vinyl acetate)
Authors: Servotte A. , Desreux V. 
Published: June 2010

AbstractThe thermal degradation of poly(vinyl acetate) under high vacuum between 230 and 300°C. was investigated by gas chromatographic analysis of the volatile products, rate measurements by the loss‐of‐weight method, and infrared determinations of the residue at different stages of the reaction. Acetic acid was proved to be the main component of the volatile products (90 to 95%). Kinetic measurements of numerous samples obtained in different polymerization conditions showed that the rates of degradation were identical for all the samples and, in particular, independent of the molecular weight. This is contrary to data previously published. Infrared absorption shows a progressive deacetylation of PVAc; very little absorption appears in the region of conjugated double bonds. A crosslinking reaction probably occurs in the very early stages of the degradation and, on the basis of C–H analysis, one has to admit that a chain‐breaking process coexists with the deacetylation reaction.
Some remarks on light scattering by solutions of highly polydisperse polymers
Authors: Kratochvíl Pavel 
Published: June 2010

AbstractSome remarks on the light‐scattering behavior of polydisperse systems and on the methods of interpreting the light‐scattering curves are presented. P(θ) functions for systems of linear Gaussian and branched coils with Schulz‐Zimm and generalized exponential distribution were calculated.
Syndiotactic polymerization of methyl methacrylate
Authors: Abe H. , Imai K. , Matsumoto M. 
Published: June 2010

AbstractTypical Ziegler‐type catalysts derived from AIR3 and TiCl4 were found to be effective in the syndiotactic polymerization of methyl methacrylate at low temperatures. The influences of polymerization variables on the polymer yield, the molecular weight of the polymer produced, and the syndiotactic regulating capacity of the catalysts were investigated. In general AlEt3/TiCl4 molar ratios of 3:10 mixing of both the catalyst components and aging of the catalyst system in the temperature range of −30 to 30°C. using aromatic hydrocarbon solvents such as toluene as a polymerization medium, and low polymerization temperature, such as −78°C. are the preferred conditions for the formation of syndiotactic, high molecular weight poly(methyl methacrylate) in high yield. From the results of testing catalyst activities of the separated catalyst systems it was concluded that some cooperation between AIR3 and the insoluble Ti halide compound obtained by the reduction of TiCl4 with AIR3 is essential for the formation of syndiotactic poly(methyl methacrylate).
Studies on Japanese lacquer: Film formation via o‐quinone and enzymic oxidation of urushiol homologues catalyzed by laccase
Authors: Kumanotani Ju , Kato Takashi , Hikosaka Aizo 
Published: June 2010

AbstractThe mechanism of enzymic film formation of Japanese lacquer via o‐quinone derived from urushiol is revealed by the spectral and molecular‐weight changes of the substrate under mild enzymic oxidation as well as by the laccase‐catalyzed aqueous reaction of urushiol homologues.
Studies of the active complex of a soluble catalyst. I. Ti(O‐n‐Bu)4–AlEt3 system
Authors: Takeda Masatami , Iimura Kazuyoshi , Nozawa Yasuo , Hisatome Masao , Koide Naoyuki 
Published: June 2010

AbstractThe characterization of an active complex in a soluble Ti(O‐n‐Bu)4‐AlEt3 system is reported in connection with its polymerization activity for styrene. The catalytic activity strongly depends on the Al/Ti ratio in the catalytic system. The optimal Al/Ti ratio for polymerization reaction is estimated as 1,5. Active titanium species are present in trivalent state. Further reduction of titanium species to a valency of less than 3 results in no activity for styrene polymerization. Two types of active species are detected by the IR and ESR studies of the catalytic system. One is Ti(O‐n‐Bu)2Et, and the other is a complex formed by 1 mole of Ti(O‐n‐Bu)2Et and 2 moles of (n‐BuO)‐AlEt2. The differences in activity between these are now under investigation. IR and ESR studies of the Ti(O‐n‐Bu)3‐AlEt3 system are also reported.