bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress‐strain‐time relation of poly(n‐alkyl methacrylates) in rubbery state
Authors: Hata Toshio , Nose Takuhei
Published: June 2010

Measurements 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

The 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

Vitreous 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

Crystallization 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

An 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

New 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

The 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

Fibers 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

The “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

This 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

Formulas 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

Gel 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

Several 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

Charge‐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

The 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

Some 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

Typical 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

The 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

The 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.
Synthesis of α,ω‐difunctional polystyrene and its reaction with diisocyanates
Authors: Shimura Yukio
Published: June 2010

α,ω‐Dihydroxyl polystyrene was synthesized by anionic polymerization of styrene, followed by the addition of ethylene oxide. The polymerization was carried out either in tetrahydrofuran or in dioxane, with alkali metal complex of naphthalene, biphenyl, or α‐methyl styrene. The molecular weight of the hydroxyl‐ended polystyrene obtained ranged from 800 to 12,000. Polyurethanes were obtained by treating the polystyrene with diisocyanates such as tetramethylene‐, p‐phenylene‐, 1,5‐naphthalene‐, and diphenylmethane‐diisocyanate. Molecular weight increase due to the polyurethane formation varied with the condition, but some of the resulting polymers showed increases of more than thirty times that of the initial polystyrene.
Synthesis of block polymers by homogeneous anionic polymerization
Authors: Fetters L. J.
Published: June 2010

The advent of the homogeneous, termination‐free anionic polymerization systems has proven to be a valuable synthesis tool for the polymer scientist. The absence of a spontaneous termination reaction in these systems makes it feasible to form a variety of interesting polymeric materials, i.e., linear, block polymers, star‐shaped polymers, and well‐defined graft polymers, as well as chains garnished at the end (or ends) with reactive groups. Recently linear block polymers of styrene and butadiene have achieved commercial importance. This review covers the synthesis methods of these block polymers and touches briefly on the formation of other block polymers by diverse synthesis routes.
Effect of sequential arrangements on block copolymer properties
Authors: Ceresa R. J.
Published: June 2010

The solution, melt, and solid–state properties of a range of block co‐polymers are considered in relation to the sequential arrangement within the macromolecule. An attempt is made to predict block copolymer properties from a knowledge of the homopolymer or sequence copolymer properties. The application properties of industrial systems are then reviewed in the light of the hypotheses.
Rhodium‐catalyzed emulsion polymerization of butadiene
Authors: Morton Maurice , Das B.
Published: June 2010

Recent work has shown that rhodium salts in aqueous solution are capable of polymerizing butadiene to a high trans‐1,4 polymer, especially in the presence of certain surfactants of the sulfate or sulfonate types, which act as ligands for the rhodium. It has now been confirmed that the effective surfactants are of two types: sodium lauryl sulfate and the sodium alkyl benzene sulfonates having alkyl chains greater than C5. Studies of these systems have also been conducted in homogeneous solution, in an attempt to elucidate the mechanism. For this purpose, solvents such as tetrahydrofuran, dimethoxyethane, and the dimethyl ester of ethylene glycol were found to be effective. However, the polymerization rate was much slower than in the heterogeneous aqueous systems and also appeared to be independent of the presence of the surfactant. This phenomenon was apparently due to the fact that these solvents also act as ligands for the rhodium, thus giving rise to catalyst complexes which are less effective in polymerization.
Kinetic study on the alkaline degradation of amylose
Authors: Lai Yuan‐Zong , Sarkanen K. V.
Published: June 2010

The kinetics of end‐wise degradation of amylose has been studied varying base concentration and temperature. At 100°C, the rate of peeling increases with hydroxyl ion concentration up to 0.1 N base concentration, remaining constant thereafter, whereas the rate of termination continues to increase beyond this point levelling off finally to a constant value at approximately 1.5 N base concentration. As a consequence, the ratio of peeling to termination is sufficiently high in 0.01–0.1 N sodium hydroxide solutions to effect total degradation of amylose. The kinetic pattern is interpreted in terms of mono‐ and di‐ions of the reducing end‐groups acting as reactive intermediates. The potential application of the peeling reaction to structural studies of polysaccharides is discussed.
Light scattering by cellulose. I. Native cellulose films
Authors: Borch J. , Marchessault R. H.
Published: June 2010

Crystalline cellulose films are analyzed by solid‐state light scattering, using a photographic technique. The light‐scattering envelopes may be theoretically predicted by assuming a model consisting of randomly oriented anisotropic rods. The experimentally observed anisotropy patterns are discussed in terms of this model and are related to various ways in which the fibrils may aggregate. These are often visible in electron micrographs of cellulose materials. The method is applicable to paper samples which are sufficiently thin and dense.
Photoconducting pyrrone polymers
Authors: Reucroft P. J. , Scott H. , Serafin F. L.
Published: June 2010

Pyrrone polymers are found to exhibit substantial photoconductivity, photocurrent‐dark current ratios of up to 300 being obtained with incident intensities of polychromatic light of 10–20 m.w./cm2. The condensation product obtained from 3,3′, 4,4′‐benzophenone tetracarboxylic dianhydride and 3,3′, ‐diaminobenzidine (BTDA‐DAB) is about 4 to 5 times more photoresponsive than the product obtained from pyromellitic dianhydride and the same diamine (PMDA‐DAB). Maximum photoresponese in obtained when samples are cured for at least 24 hours at 300°C. A linear dependence of photocurrent on voltage is found in the range 102 to 105 volts/cm. The temperature dependence of photocurrent indicates that photocarriers: are produced by more than one mechanism in the temperature range from room temperature to 300°C. Photoresponse is found to be maximum in the ultraviolet‐visible region, with a peak response at 610 mμ for PMDA‐DAB and 550 mμ for BTDA‐DAB.
Relationships among melt flow, glass transition temperature, and inherent viscosity of thermoplastic polyesters
Authors: Combs R. L. , Nations R. G.
Published: June 2010

The melt flow (MF) (an inverse function of melt viscosity) for a wide variety of polyesters has been related in one equation to their glass transition temperatures (Tg), their inherent viscosities, and their melt temperatures. This empirical equation was developed by regression methods on various relationships. Although it contains only three constants, it gives a good fit of the data. Such an equation allows prediction of the processability of a polyester providing its Tg and its inherent viscosity are known. Only a small amount of sample is required for these two measurements. The form of this equation presents an interesting speculation: perhaps there is a constant ratio of the energy of activation for viscous flow at constant shear rate to the Tg.
Rapid determination of crosslink densities and interaction parameters from swelling rate data
Authors: Schreiber H. P. , Holden H. W. , Barna G.
Published: June 2010

Gravimetric determinations of weight gain were carried out for ethylene‐propylene elstomer (EPR) samples crosslinked by dicumyl peroxide and immersed for periods up to IS minutes in various swelling solvents. The weight gain data were analyzed on the assumed existence of a power‐law relationship with immersion time as well as the more usual assumption that the swelling rate is diffusion‐controlled. The former analysis led to strong correlations between initial swelling rates and the Flory‐Huggins interaction parameter of a polymer‐solvent pair. The latter analysis correlated initial uptake rates with crosslink densities obtained from equilibrium swelling results. Initial uptake rates were used to estimate the interaction parameter for the system EPR‐tetrahydronaphthalene, and to measure the effect of rutile and carbon black filler on the cross‐linking process. Rutile behaved as an inert filler, but results for carbon black proved anomalous, indicating need for further study.
The determination of the molecular weight and molecular weight distribution of dehydrogenase polymers of coniferyl alcohol and lignins
Authors: Soundararajan T. N. , Wayman Morris
Published: June 2010

This paper describes experiments aimed at the development of a convenient method of determining the molecular weight and the molecular weight distribution of lignins and lignin‐like polymers. As a model, a polymer of coniferyl alcohol prepared by enzymatic dehydrogenation was fractionated on columns of Sephadex G 75, G 100 and a mixture of G 75, G 100 and G 200 of equal volumes swollen in dimethyl sulphoxide. The columns were calibrated by means of sharp fractions obtained by preparative fractionation characterized independently by sedimentation equilibrium ultracentrifugation. From the elution curve of the sample and the calibration curve the molecular weight and its distribution were calculated. The assumption that the system predicts the molecular weight and its distribution correctly was tested by running a sample whose molecular weight distribution was known by ultracentrifugation. The distribution calculated from the gel column chromatograph was found to coincide with that obtained by ultracentrifugation. The molecular weights and their distributions obtained on milled wood lignin samples by this method appear to be reasonable.
Relation of glass transition temperature to molecular structure of addition copolymers
Authors: Barton John M.
Published: June 2010

An equation is proposed relating the glass transition temperature (TG) of copolymers to their molecular structure in terms of the mole fractions of the various diad sequences of monomer units combined in the copolymer chain, and temperature parameters (Tij) characteristic of each type of sequence, ij. The equation, an extension of the Gibbs and DiMarzio copolymer TG theory, accounts for the effect on TG of the different types of bonds between repeating units in different diad sequences, and is in its general form: \documentclass{article}\pagestyle{empty}\begin{document}$ T_G = \sum\limits_{i,j} {n'_{ij}} T_{ij} $\end{document}. In a binary copolymer of structure [(a) × (b)y] n, corresponding to the ij sequences ‐aa‐, ‐ba‐, ‐ab‐, and ‐bb‐. The term n'ij is the mole fraction of ij sequences, nij weighted according to the number of rotatable bonds per sequence, αij, and \documentclass{article}\pagestyle{empty}\begin{document}$ n_{ij} = n_{ij} \alpha ij/\sum\limits_{i,j} {\left({n_{ij} \alpha _{ij}} \right)} $\end{document}. The variation in the distribution of sequences with overall composition is obtained from the copolymerization reactivity ratios. The theory, which quantitatively describes the sometimes observed maximum or minimum in TG ‐ composition plots, gives good agreement with published data for 11 copolymer systems. Application of the theory to give homopolymer TG's by extrapolation is demonstrated. Inter‐relations are found with other published theories of copolymer TG.
The circular dichroism of polynucleotides in relation to their conformations
Authors: Imahori Kazutomo , Watanabe Kimitsuna
Published: June 2010

The circular dichroism of polynucleotide or oligonucleotides reflects their conformations. The CD spectra of oligonucleotides vary depending upon the species of bases involved and their sequence. The amplitude of CD peak is proportional to the degree of stacking and furnishes the way to estimate some thermodynamic parameters of stacking. The CD spectrum of poly (G + C) or poly (A + U) is close to the graphical summation of its constituent homopolymers, except blue shift of the peaks, and decrease in their amplitudes. Double stranded copolymer, poly (A ‐ U) or poly (G ‐ C) has a quite different feature from that of poly (A + U) or poly (G + C), reflecting the difference in mode of base stacking. The CD spectrum of poly dAT is quite different from poly (A ‐ U) and DNA has a different CD pattern from RNA. These differences can be interpreted by the difference in the geometry of the bases. The peak position of CD spectrum of double stranded RNA varied depending on the ratio of (G ‐ C)/(A ‐ U). Thus it is possible to estimate (G ‐ C) or (A ‐ U) content by analyzing the CD spectrum. The CD spectra of tRNA are different depending on the species of it. It is of greatest interest that Met‐tRNAF has quite different CD pattern from Met‐tRNAM. This can be interpreted by the difference in the number of G ‐ C or A ‐ U pairs between them. A remarkable change in CD spectrum was observed when poly dAT is complexed with RNA polymerase or when aminoacyl RNA is complexed with T factor. The conformational change suggested by CD will play an important role for the elucidation of reaction mechanism.
Studies in the polymerization of methyl methacrylate with VCl4‐Al (C2H5)3 catalyst system in acetonitrile
Authors: Dixit Sunit S. , Deshpande A. B. , Kapur S. L.
Published: June 2010

Methyl methacrylate has been polymerized at 40°C with VCl4‐AlEt3 catalyst system in acetonitrile. A linear dependence of rate of polymerization on the monomer and catalyst concentrations as well as overall activation energy of 10.96 kcal/mole exhibits coordinated anionic mechanism. However, characterization of the structure of the polymer by NMR spectra revealed the presence of heterotactic units, whereas on the addition of hydro‐quinone to the catalyst system, the polymer obtained was a stereoblock. The mechanism of polymerization is discussed in the light of the kinetic studies and the structure of PMMA.
relation between the polymer conformation and the elastic modulus of the crystalline region of polymer
Authors: Sakurada Ichiro , Kaji Keisuke
Published: June 2010

The force required to stretch a polymer chain by 1% (f value) was calculated from experimental values of elastic moduli E1 in the direction of molecular axis and the cross‐sectional area of the molecule of 25 well known polymers. The f value is mainly dependent on the conformation of a molecule and almost independent of side groups. The f values of polymers of various types of conformation may be summarized as follows: T type, 4−5 × 10−5 dyne; TGTG type, 1.5 × 10−5 dyne; TG(3/1) type, 1 × 10−5 dyne; T′G′ (7/2) type, 0.58 × 10−5 dyne; T′G′ (4/1) type, 0.36 × 10−5 dyne; TTGG type, 0.29 × 10−5 dyne; where T, G, and G mean trans, gauche and minus gauche, respectively, and the numbers in the parentheses denote helical structures. The reason for an anomalous apparent E1 value of nylon 6 (α‐form) previously reported was elucidated; it was confirmed that E1 exhibits a value expected for a polymer with a nearly extended zigzag conformation.
Poly(ethylene sulfide). I. Unique seed polymerization technique‐growth of “immortal” polymer
Authors: Gobran Riad H. , Larsen Roy
Published: June 2010

Poly(ethylene sulfide) was prepared by a unique two‐step polymerization technique in which a “seed polymer” was initially formed, compacted to a desired bulk density, and then used to polymerize fresh ethylene sulfide monomer. The seed polymer was prepared by reacting ethylene sulfide with diethylzinc‐water in a suitable solvent. The final polymer was an exact magnification that faithfully reproduced any shape of seed used with regard to relative dimensions, angularities, curvatures and even imperfections. Poly(ethylene sulfide) prepared by this process can be used for successive polymerizations that proceed at the same rate as the original seed with comparable zinc content, and thus behaves as an “immortal” polymer. The high molecular weight polymer melts above 200°C, is highly crystalline, and is, insoluble in most organic solvents at ordinary temperatures. A number of solvents dissolve the polymer above 140°C at which temperature thermal degradation takes place. When the polymer is stabilized by use of certain thermal stabilizers, it can be successfully molded to give excellent physical and mechanical properties.
Some effects on polycondensation reactions
Authors: Ogata Naoya
Published: June 2010

The effect of solvents or chelating agents on polycondensation reactions was investigated. Solution polycondensation of nylon 66 salt was enhanced in ketone solvents such as methyl acetophenone or diisobutyl ketone, a polyamide of high molecular weight being formed. Room‐temperature polycondensation of N‐(hydroxyethyl)‐β‐alanine ester or 4‐thio‐e‐aminocaproate was influenced by solvents and chelating agents with functional groups, and the rate or the equilibrium of the reaction were apparently changed. Interfacial polycondensation of m‐phenylenediamine and isophthaloyl chloride yielded aromatic polyamide having a high molecular weight in ketone solvents such as cyclohexanone or methyl acetophenone. It was found that isophthaloyl chloride reacted slowly with cyclohexanone to yield quantitatively isophthalic acid. These effects of solvents or chelating reagents on polycondensation reactions might be attributed to the reactivity change of functional group during polycondensation reactions.
Small‐angle and wide‐angle X‐ray investigations on poly‐m‐bromostyrene and poly‐o‐bromostyrene in benzene solution
Authors: Durchschlag H. , Puchwein G. , Kratky O. , Breitenbach J. W. , Olaj O. F.
Published: June 2010

Various fractions of poly‐m‐bromostyrene and poly‐o‐bromostyrene in benzene were studied by the small‐angle and wide‐angle x‐ray methods. The combination of the two methods makes it possible to supply information on short‐range order and long‐range order in the same molecule. Four fractions of poly‐m‐bromostyrene of the approximate ratio of the degrees of polymerization (1:2:3:4) were studied. The molecular weight was determined from the absolute intensity of the small‐angle scattering at zero angle and the radius of gyration from the slope in the Guinier plot. The concentration dependence of both figures is discussed. The determination of the persistence length is not directly possible but results after elimination of the cross‐section factor (a = 17.3 Å). It is on the average about 20% smaller than the value calculated from the hydrodynamic length L and the radius of gyration Rexp supposing a Gauss coil, which can be explained by polydispersity and by the fact that benzene does not represent a Θ‐solvent but is better than this. The scattering curves of poly‐m‐bromostyrene solution and of a solution of m‐bromotoluene containing the same number of bromine atoms show no difference in the exactly measured wide‐angle field, which indicates that with the polymer product the distances between the bromine atoms are irregular. With poly‐o‐bromostyrene two possibilities of subtraction of a blank solution were compared. The small‐angle investigations of poly‐o‐bromostyrene permitted the determination of the molecular weight, radius of gyration, persistence length, radius of gyration of the cross section, mass per unit length, and hydrodynamic length. The high mass covering per unit length (Mq ≃ 90–100/Å), the large radius of gyration of the cross‐section (Rq ≃ 4.4 Å), and the large radius of the cross‐section, obtained in three independent ways (rq ≃ 6 Å) afford indications for the appearance of helical ranges in solution. A further support for this is the discovery of a definite interbromine spacing (l = 4.6 Å) by wide‐angle studies. This can only be explained by order of the bromine atoms over a certain range. On the other hand the presence of large coil ranges is shown by the direct determinability of the persistence length (a = 16.5 Å) from the transition point in the plot of I (2θ)2 against (2θ) as well by the not too great deviation from the Gaussian statistic of the coil. The most plausible explanation of all findings with poly‐o‐bromostyrene is that helical and coil ranges coexist in solution. The helical zones will, however, not extend over any too great range, so that the general impression of a wormlike chain remains. The verification of the procedure of interferometric measurement of defined spacings of heavy atoms in molecules is made with the example of the 2,5‐dibromotoluene by remeasurement of the known interbromine spacing.
Failure surfaces in principal stress space
Authors: Tschoegl N. W.
Published: June 2010

Criteria for failure in multiaxial states of stress have associated with them geometrical representations as surfaces in principal stress space. Any combination of stresses is safe if the corresponding point in principal stress space falls within the failure surface. The material will fail if the point lies on or outside of the surface. The geometry of some simple surfaces and means for determining them on isotropic bodies are discussed, and the scanty information on failure surfaces for polymeric materials is reviewed.
Friedel‐crafts and related reactions on poly(vinyl chloride)
Authors: Hace D. , Bravar M.
Published: June 2010

Polyvinyl chloride solubilized in an appropriate solvent can be transformed to a complex mixture of chemical compounds by treating it with aromatics in the presence of Friedel‐Crafts catalysts.

The primary reaction is the alkylation of aromatics with polyvinyl chloride; it is followed by other parallel and secondary reactions, viz., intramolecular cyclizations of alkylated products and a cleavage of molecules to fragments of lower molecular weight. All this is accompanied by the process of hydrogen chloride elimination from the reacting polymer. The chlorinated hydrocarbons, when used as solvents can also take part in reactions, leading to the crosslinking of polymers.

An earlier work of Belgian authors (Teyssié, Smets) was continued in order to elucidate further the complex of the reactions mentioned above. A number of Friedel‐Crafts condensations were carried out using polyvinyl chloride to alkylate benzene and toluene in various solvents, such as 1,2‐dichloroethane, cyclohexanone, trichloroethane and tetrahydrofurane in the presence of AlCl3 and BF3 as catalysts. The kinetic curves representing the dehydrochlorination process were obtained, allowing the interpretations of the mechanisms involved. The products thus obtained were characterized by physical and chemical means. The significant peaks in IR‐spectra which would account for the intramolecular cyclizations and branching of macromolecular chains were also observed.
Measurement of interfacial and surface tensions in polymer systems
Authors: Patterson H. T. , Hu K. H. , Grindstaff T. H.
Published: June 2010

Princen's modification of Vonnegut's rotating drop procedure for measuring inter‐facial tension between low viscosity liquids has been adapted for use with pairs of liquid polymers with viscosities up to 5000 poise. Extrapolation to infinite time of results obtained with 10–20 min of rotation provided steady state data as indicated by its corre‐spondence with results reported from other techniques. An adaptation of this procedure was also found useful for determining surface tension values of molten polymers at temperatures up to 290°C. Reductions of 60–70% in interfacial tension between viscous samples of a polydimethylsiloxane and a copolyether were accomplished by addition of 1–2% of amphi‐pathic or polar compounds such as polydimethylsiloxane‐polyoxyethylene copolymers and carboxyl‐substituted polydimethylsiloxanes. A linear reduction in interfacial tension with a logarithmic increase of additive concentration was noted.
Polypeptide hormones and lipid monolayers
Authors: Pak Charles Y. C. , Kafka Marian S.
Published: June 2010

The monomolecular film of monooctadecyl phosphate (mOP) spread at an air‐water interface was employed to elucidate the nature of the interaction between peptide hormones and the cell membrane. First, the effect of peptide hormones on the uptake of calcium ion (Ca++) by the monolayer was examined from the emission of45 Ca radioactivity through the monolayer. Insulin inhibited the initial uptake of Ca++ and facilitated the release of adsorbed Ca++. These effects were partially or completely lost with insulin analogs. Vasopressin and oxytocin inhibited the adsorption of Ca++. Vasopressin facilitated Ca++ release, whereas oxytocin did not. Thyrocalcitonin profoundly inhibited Ca++ uptake, but facilitated only slightly the release of Ca++. Parathyroid hormone had negligible effect. The molecular basis and the biological significance of these results are discussed. Secondly, the effect of peptide hormones on the transport of water through the mOP monolayer was examined. Ca++ increased the specific resistance to evaporation of water. In the presence of Ca++, insulin and vasopressin lowered the resistance to evaporation (or increased the trans‐port of water). This effect of the hormones could not be accounted for entirely by the inhibition of Ca++ uptake.
Monolayers of polyorganosiloxanes on water
Authors: Noll W. , Steinbach H. , Sucker Chr.
Published: June 2010

Linear organosiloxanes with various substituents differ in their spreading velocities and with respect to the film structure formed on aqueous substrates. The material investigated allows a distinction between siloxanes in which the molecules placed on the subphase in helical form become oriented on the surface of the water to form “spreading chains” and siloxanes in which this is not the case. It is believed that hydrogen bridging is responsible for the orientation effect.

Within the first group, a distinction can be made between polymers which on strong compression are lifted off from the water and can be returned to the helical form, and those in which due to great hydrophilicity of the substituents release of “dry” spreading chains from the water can not be achieved. Methyl‐substituted siloxanes, among them especially the dimethyl‐ and methyl‐H‐siloxanes, show quick spreading and good orientability. This may explain why these siloxanes play such an important role since the beginning of silicone technology up to the present day as interfacially active substances. But this behavior is not representative for organosiloxanes in general.

The structure of the siloxane skeleton seems to have no decisive influence on the spreading phenomena. Branched or crosslinked methylsiloxanes behave similar to the linear ones and form also, by and large, monomolecular films.

Hydrate phases, i.e., mixed phases of the spread substance and the subphase, play an important part in the interpretation of the force/area (F/A) isotherms.