bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential effects of the aromas of Salvia species on memory and mood
Authors: Moss Lucy , Rouse Michelle , Wesnes Keith A. , Moss Mark
Published: June 2010

This study investigated the potential for the aromas of the essential oils of Salvia species to affect cognition and mood in healthy adults. Research has demonstrated that orally administered Salvia officinalis and Salvia lavandulaefolia are capable of modulating cognition and mood. The active compounds in the herbal products might also be present in the aromas and so produce similar effects. In an independent groups design, three conditions, S. officinalis aroma, S. lavandulaefolia aroma and no aroma were employed. One hundred and thirty‐five healthy volunteers acted as participants, with 45 in each condition. Cognitive performance was assessed via the Cognitive Drug Research (CDR) System. Bond–Lader mood scales measured the participants’ mood on three dimensions before and after the cognitive tasks. Data analysis revealed that the S. officinalis aroma group performed significantly better than the control group on the quality of memory and secondary memory primary outcome factors from the test battery. The Alert mood measure displayed significant differences between both aromas and the control condition. These findings suggest that the aromas of essential oils of Salvia species reproduce some but not all of the effects found following oral herb administration, and that interesting dissociations occur between subjective and objective responses. Copyright © 2010 John Wiley & Sons, Ltd.
SEDVIEW, Real‐time Sedimentation Analysis
Authors: Hayes David B. , Stafford Walter F.
Published: June 2010

The ability to obtain a sedimentation coefficient distribution as the run proceeds, and to get an early idea of the quality of a particular sample, has not been made available in real‐time during the run in any of the existing software packages. It is desirable on many occasions to be able to see the number of components present in a sample at an early stage of the run. The ability to ascertain the extent of heterogeneity of sample would help enormously to reduce the amount of time that is necessary to obtain that information. Most software packages currently available require that the run be completed before analysis is carried out or at least some of the early scans analyzed off‐line to determine if the run should continue. A software package called SEDVIEW has been developed by us to allow early analysis in real‐time.

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Effect of the Deformation Temperature on the Shape‐Memory Behavior of Epoxy Networks
Authors: Feldkamp Diane M. , Rousseau Ingrid A.
Published: June 2010

The impact of the deformation conditions, specifically the temperature, on the shape‐memory behavior and characteristics of epoxy SMPs is studied. By simply varying the temperature during deformation (i.e., the programming step of the SM effect), the ultimate strain of the formulated epoxy was improved three‐ to five‐fold, thereby providing for an increased range of reachable deformation strains during SM thermo‐mechanical cycling. This research unveils newly developed epoxy‐based SMPs with improved deformability range and high strength with intrinsically good thermal and chemical stability.

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Water purification by membranes: The role of polymer science
Authors: Geise Geoffrey M. , Lee Hae‐Seung , Miller Daniel J. , Freeman Benny D. , McGrath James E. , Paul Donald R.
Published: June 2010

Two of the greatest challenges facing the 21st century involve providing sustainable supplies of clean water and energy, two highly interrelated resources, at affordable costs. Membrane technology is expected to continue to dominate the water purification technologies owing to its energy efficiency. However, there is a need for improved membranes that have higher flux, are more selective, are less prone to various types of fouling, and are more resistant to the chemical environment, especially chlorine, of these processes. This article summarizes the nature of the global water problem and reviews the state of the art of membrane technology. Existing deficiencies of current membranes and the opportunities to resolve them with innovative polymer chemistry and physics are identified. Extensive background is provided to help the reader understand the fundamental issues involved. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010
Aggregation, gelation instability, and morphologies of diblock copolymers consisting of poly(p‐benzamide) and poly(m‐benzamide)
Authors: Kataoka Toshiyuki , Ohishi Tomoyuki , Yokozawa Tsutomu , Ikehara Takayuki
Published: June 2010

The solution, gelation, and morphological properties of monodisperse aromatic polyamide diblock copolymers consisting of poly(p‐benzamide) (PpBA), poly(m‐benzamide) (PmBA), and poly(N‐octyl m‐benzamide) (POmBA) were investigated. The block copolymers of these polymers, PpBA‐block‐POmBA and PmBA‐block‐POmBA, formed spherical micelles or amorphous aggregates in many solvents in addition to physical gels at concentrations higher than 5 wt %. A temperature‐induced sol‐gel transition was also exhibited for PpBA‐block‐POmBA in solvents with high boiling points such as N,N‐dimethylacetamide and N‐methylpyrrolidone (NMP), although the transition was not entirely thermoreversible; the transition temperature decreased by annealing at ∼80 °C. Dynamic light scattering measurements of the PpBA‐block‐POmBA/NMP solutions revealed that metastable micelles in the sol state reorganized into smaller micelles upon annealing at 90 °C. The block copolymer, which forms strong associations, exhibited some transient structure as indicated by the need to sufficiently anneal the solution to reach equilibrium. Network‐like patterns with characteristic length of ∼10 μm appeared on the gel surfaces upon evaporation of volatile solvents such as dichloromethane and chloroform, in which the copolymers were observed to aggregate. The unique properties of the copolymers originate from interactions between the highly polar NH aromatic polyamide blocks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1732–1739, 2010
Characterization and electrical transport properties of polyaniline and multiwall carbon nanotube composites
Authors: Chakraborty G. , Ghatak S. , Meikap A. K. , Woods T. , Babu R. , Blau W. J.
Published: June 2010

Polyaniline/multiwalled carbon nanotube (PANI/MWNT) composites were prepared by in situ polymerization. Scanning electron microscope, X‐ray diffraction, Fourier transform infrared, Uv‐Visible spectroscopy, Fluorescence spectrophotometry were done to characterize the PANI/MWNT composites. Thermal stability was measured by thermogravimetry analysis. The thermal stability of PANI/MWNT composites becomes higher than PANI. Electrical transport properties of different PANI/MWNT composites were investigated in the temperature range 77 ≤ T ≤ 300 K with and without magnetic field up to 1 T. The dc resistivity of PANI/MWNT composites shows different behavior compared to the sample without MWNT. The room temperature dc magnetoconductivity of the samples is negative; however, its sign changes to positive by lowering the temperature, which has been explained by hopping type charge transport. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1767–1775, 2010
Streaming birefringence of polymer solutions
Authors: Philippoff W.
Published: June 2010

Streaming or flow‐birefringence is the optical anisotropy induced by laminar flow in liquids. The optical anisotropy can lie described by an optical tensor which is coaxial with the stress tensor in an elastic material In a tension experiment this is obvious. In laminar flow this has been proved by investigating the distribution of the birefringence in three directions of space. The amount of anisotropy, usually described by the degree of birefringence Δn, is proportional to the difference in principal stresses of the mechanical stress tensor in a very large range of variables, therefore giving the possibility of using optical measurements for the determination of mechanical stresses. However, the relationship is valid either for concentrated solutions or for conditions where the solvent and the polymer have essentially the same index of refraction n—a condition usually termed matching solvent. The proportionality constant between the difference in principal stresses and Δn—the stress‐optical coefficient C—is, as also follows from theory, independent of concentration, shear stress temperature, molecular weight and its distribution, only determined by the structure of the monomer unit and its n. Another quantity in flow birefringence is the so‐called extinction angle which is measured between the direction of the principal optical axis and the direction of flow. A reasonable amount of experimental data has been obtained to show that this angle can be quantitatively correlated with the so‐called “recoverable shear” that is the shear component of the elastic strain tensor in laminar flow. Therefore, the experimental determination of the angle gives a measure of the elastic strain. A survey of the experimental results in the field shows the generalities of this approach in a variety of polymer and solvent systems.
Kinetics of thermal degradation of char‐forming plastics from thermogravimetry. Application to a phenolic plastic
Authors: Friedman Henry L.
Published: June 2010

A technique was devised for obtaining rate laws and kinetic parameters which describe the thermal degradation of plastics from TGA data. The method is based on the inter‐comparison of experiments which were performed at different linear rates of heating. By this method it is possible to determine the activation energy of certain professes without knowing the form of the kinetic equation. This technique was applied to fiberglass‐reinforced CTL 91‐LD phenolic resin, where the rate law ‐ (1/we)(dw/dt) = 1018 e−55,000/RT [(w ‐ wf)/w0,]5, nr.−1, was found to apply to a major part of the degradation. The equation was successfully tested by several techniques, including a comparison with constant temperature data that were available in the literature. The activation energy was thought to be correct within 10 kcal.
Form III to form II phase transition of polybutene‐1
Authors: Geacintov C. , Schotland R. S. , Miles R. B.
Published: June 2010

The Form III to Form II transition of crystalline potybutene‐1 at elevated temperature has been observed by differential thermal analysis (DTA), dilatometry, x‐ray diffraction, and photomicrography. DTA thermograma of polybutene‐1 in Form III were found to exhibit endotherms at 94°C., and 110°C, corresponding to the transformation of Form III and melting of Form II, respectively. The origin of an exothermic peak observed at 90°C, is not entirely resolved at the present time. The transition of poly‐biitene‐1 in the Form III modification was also studied by x‐ray diffraction methods. It was shown that the intensity of the peak at 2θ = 12.1°, corresponding to the Form III crystalline phase, begins to decrease in sine at 88°C, while simultaneously the peak at 2θ = 11.7°, corresponding to the Form II modification, starts to grow. The transformation is complete at 98°C. The nature of the Form III to Form II transition of polybutene‐1 is discussed in the paper; two alternative mechanisms are deemed possible: a solid‐solid transition or a transition involving a short‐lived intermediate molten state.
Characterization of stereochemical regulation in polypropylenes
Authors: Woodbrey James C. , Thementozzi Q. A.
Published: June 2010

The high‐resolution proton magnetic resonance (PMR) spectra of very highly isotactic, very highly syndiotactic, and stereoblock polypropylenes in o‐dichlorobenzene solutions have been examined. The effects of stereoregulation on proton shieldings and some of the complexities of the methylene proton resonances are discussed. Tactic placement contents were determined for several polymers by a method based on the methylene proton resonances. Tactic pair contents were determined for two stereoblock fractions by a method based on the methyl proton resonances. These results revealed much higher stereoblock characters than those determined previously for the same fractions from melting data. All of the PMR results were in very good accord with the results obtained on several polymers by infrared, x‐ray diffraction, and differential thermal analysis. Two highly isotactic polypropylenes, having essentially the same molecular weights and molecular weight distributions and tactic placement contents differing by no more than the PMR experimental error in precision of ±2%, were shown to have significantly different modulus‐temperature characteristics when identically drawn and annealed. Though such variations in moduli must stem from differences in orystal‐lizabilities, and thus also in stereo regularities, present results do not permit a clear interpretation of the variations in moduli in terms of differences in tactic placement contents or stereoblock characters.
Review of solution methods and certain other methods of polymer fractionation
Authors: Schneider Nathaniel S.
Published: June 2010

Discrimination in terms of solubility differences forms the basis of the most widely applicable methods of polymer fractional ion. These include fractional precipitation and extraction on a batch scale; the rapid column methods, namely, the elution method and precipitation chromatography; and turbidimetric titration, which is strictly an analytical procedure. The principles of solution fractionation are reviewed as applied to batch fractionation and to the column methods, and certain essential differences are pointed out between these two approaches. The importance of proper solvent selection in the several methods is considered, and examples are presented of fractionation on the basis of chemical and structural differences as well as in terms of molecular weight. A brief summary is also presented on the present status of certain other methods, including thermal diffusion, none refining, and adsorption chromatography, which utilize different physical principles as the basis of separation.
Diffusion of penetrants in polymers
Authors: Frisch H. L.
Published: June 2010

Many anomalous features of the diffusion of penetrants into polymers, around and below the glass transition, such as the occurrence of history‐dependent diffusion coefficients, sigmoid and “two‐stage” sorption, and time‐dependent boundary conditions, can be shown by non‐equilibrium thermodynamics to be consequences of a simple model of a glasslike transition. Below the transition temperature the system is viewed as undergoing a generalized relaxation with respect to certain characteristic internal variables of even tensorial rank, while above the transition temperature the system is viewed to be in internal equilibrium with respect to these variables. It is pointed out that the mechanism of Fickian diffusion above the glass transition may depend on the distribution of sizes of cavities, particularly the mean cavity volume, as well as the total free volume of the system.
The acidic groups in wood and pulp as measured by ion exchange
Authors: Sjöström Eeho , Janson Tax , Haglund Per , Enström Barbuo
Published: June 2010

The ion‐exchange capacities were determined for a variety of wood samples consisting of both softwood and hardwood. The experiments revealed that considerably more acidic groups are present in heartwood than in sapwood. The capacity (carboxyl) values found for all samples were substantially lower than would be expected from the estimated uronic acid contents. This difference was more striking for hardwood than for softwood. After alkali treatment (pH 11.5, 64°C), the exchange capacity of the wood was increased considerably and this effect was more pronounced for hardwood than for softwood. This observation either indicates the presence of carboxylic acid estera and lactones or is attributable to an increased accessibility of carboxyls. Such an increase may occur in hardwood as a consequence of the deacetylation of xylan. In another series of experiments the effect of sulfonation was studied. Wood samples (Picea abies, Betula verrucosa, and Betula pubescens) were sulfonated at various pH values at 80 and 90°C. so that only small quantities of the wood substance were dissolved. In addition, the number of acidic groups was determined for a series of spruce and birch pulps with varying lignin contents. It was possible to distinguish between the carboxyl and sulfo groups by means of an ion‐exchange method developed for that purpose. The experiments revealed that the accessibility of carboxyl groups is considerably increased even after sulfonation at a low temperature. It also became apparent that most of the carboxyl groups are accessible even in pulps with relatively high lignin contents. The carboxyl values together with xylose analyses showed that the acidity of xylan remaining in pulp is substantially decreased during cooking. This decrease is more pronounced for birchwood than for sprucewood. Finally, it is evident from these experiments that sprucewood lignin is sulfonated to a markedly higher degree than birchwood lignin.
Comparison of the configuration of β‐1,4 linked hexosans and wood xylan pentosans by means of the eizner‐ptitsyn viscosity equations
Authors: Swenson Harold A. , Schmitt Charles A. , Thompson Norman S.
Published: June 2010

The Porod‐Kratky persistence lengths, monomer and polymer radii, and Flory coefficients of a number of β0–1,4 linked hexosans have been compared to each other and to the β‐1,4 linked xylan pentosans of wood by applying the Eizner‐Ptitsyn viscosity equations to intrinsic viscosity and molecular weight analyses from a number of sources. The analyses were made on fractions of cellulose acetate, cellulose nitrate, cellulose caproate, the diethylacetamide derivative of cellulose xanthate, cellulose in cadoxene and in the alkaline ferric tartrate solvent, FeTNa, the galactomannan triacetate of guar, and the glucomannan triacetate of orchid salep tuber. Xylans from spruce and birch, polystyrene, and a branched dextran were also investigated. The persistence lengths of the hexosan derivatives, except the cellulose trinitrate, were remarkably similar and were found to vary from 48 A. for the cellulose caproate determined under theta conditions to 58 A. for the galactomannan triacetate. The persistence lengths of cellulose in the two complexing solvents (72 A.) were nearly identical, confirming that these solvents do not increase the solution dimensions of cellulose greatly. The configuration of the polymers were ranked on a common graph by plotting the log of the polymer radii to contour length ratios vs. the log of the contour length. The investigation shows that the 0–1,4 linked hexosans have a common configuration which is independent of the length of the derivative side group or of single α‐1,6 linked side groups, as in the galactomannan. The configuration of the hexosans is also independent of whether the main chain is composed of glucose or mannose, or a mixture of these sugars. The greater rigidity of the hexosans, in comparison to the pentosans, is explained in the former by hindrance between the C2 group of the one sugar with the C6 group of the next, which is absent in the pentosan that has no C6. Analogy is made to the hindered racemization in substituted biphenyls to explain the great rigidity of cellulose trinitrate, whose persistence length is 132 A.
The number‐average molecular weight of native hardwood xylans
Authors: Koshijima T. , Timell T. E. , Zinbo M.
Published: June 2010

A 4‐O‐methylglucuronoxylan has been isolated in a yield of 90% by direct alkaline extraction of trembling aspen (Populus tremuloides) wood. The number‐average molecular weights of the acetate and valerate derivatives were determined in chloroform‐ethanol and of the xylan itself in dilute cupriethylenediamine. There was no evidence for the occurrence of molecular association of the acetate in chloroform‐ethanol. Tetra‐chloroethane, dimethyl sulfoxide, and cadoxen were unsuitable solvents. The results showed that the polysaccharide had a number‐average molecular weight of 31,500, corresponding to a degree of polymerization of 200. The constants K and a in the Staudinger‐Mark‐Houwink equation were determined for cupriethylenediamine solutions of a series of celluloses and xylans, the values obtained being 2.2 × 10−2 for K in both cases, and 0.78 and 0.72 for a, respectively. It was concluded that cellulose and xylan probably have the same conformation in aqueous alkali, intermediate between a compact and a free‐draining coil. Since the xylan framework is known to contain two branches per average molecule, the results would probably also imply that the branches are relatively short.
Chain folding in oriented nylon 66 fibers
Authors: Dismore Paden F. , Statton W. O.
Published: June 2010

When heated to high temperatures under zero tension, some of the molecules in oriented nylon 66 filters change from the elongated to the folded conformation, with no change in crystal orientation. This transformation is shown by a combination of structural and physical property measurements: wide and small angle x‐ray diffraction, broad and narrow line nuclear magnetic resonance, sonic modulus, density, shrinkage, and tensile properties. A fortyfold increase of the intensity of the discrete small angle x‐ray diffraction is obtained for treatments between 160‐and 255°C. as well as an increase of the length of the long period and a change from a smeared four‐point to a sharp two‐point diagram. Wide angle x‐ray measurements show little change in crystallite orientation for treatments up to 250°C. even though much shrinkage occurs. Disruption of some type is observed by sonic measurements, as would be expected if new folds occurred. An increase of density and x‐ray crystallinity confirms that heating causes much additional crystallization. The high temperature NMR spectra for these more crystalline yarns show a much larger proportion of fluidlike segments. Shrinkage of the yarns during the heating appears to be governed by the number of folds which are introduced. Tensile strength is reduced by this introduction of folded chains.
Multiple mechanical relaxation phenomena in human hair
Authors: Wall Robert A. , Morgan Donald A. , Dasher G. F.
Published: June 2010

Stress relaxation following small tensile strain was measured for samples of normal, bleached, and permanent‐waved hair immersed in water. The measurements covered up to six decades of log time and were carried out at temperatures from 30 to 85°C. Approximation to the distributions of mechanical relaxation times show a good deal of partially resolvable fine structure. Some of the experimental distributions can be approximated by a small number of Maxwell models in parallel. The different modes of relaxation in a given sample appear to have different temperature shift factors and hence different energy requirements. The effects of bleaching are quite easily seen from the relaxation spectra, whereas the effects of permanent waving, although noticeable, are not as pronounced‐ Proposals for the mechanism of some of the modes of relaxation involve backbone conformational changes of amino acid residues. A large‐scale relaxation is found in bleached hair at temperatures from 60 to 85°C. Perhaps this involves an extensive helix‐coil transformation.
Structural studies of several helical polymers
Authors: Tadokoro Hiroyuki
Published: June 2010

An extension of Bunn's nomenclature of polymer conformation is given with several examples. The structures of polyethers expressed by a general formula [(CH2)mO]n with m = 1–4 are described and discussed with respect to the properties. Poly‐oxymethylene molecule has a helical structure which contains nine chemical units and five turns in the fiber identity period, and is the sequence of the internal rotation angle 78°13′. Detailed structure analysis of this polymer was made by the method of three‐dimensional Fourier synthesis. The diffraction data were measured on a highly ordered sample prepared from a single crystal of tetraoxymethylene by solid‐state radiation polymerization. It was deduced from the experimental results that the polyoxymethylene crystallite is composed of only one type of helix, either right‐handed or left‐handed. The poly(ethylene oxide) molecule is a loosely turned helix, and is a succession of nearly trans, trans, and gauche conformations. The structure of polytetrahydrofuran is essentially a planar zigzag. It has been also found quite recently that the third member, polyoxacyclobutane, has three types of crytalline modifications. One is planar zigzag, and the other two have longer fiber periods; T3GT3Ǧ and (T2G2)2 types. The structure of polyallene [CH2C(CH2)]n is also discussed; this polymer is a succession of nearly gauche conformations, the internal rotation angles being about 65°.
Mechanical properties and fine structure of drawn polymers
Authors: Takayanagi Motowo , Imada Kiyohisa , Kajiyama Tisato
Published: June 2010

Complex moduli of oriented specimens of polyethylene (PE), polypropylene (PP), polyoxymethylene, polyethylene oxide), and polytetrahydrofuran were measured in sheet form as a function of direction. The dynamic tensile modulus (E′) along the stretched direction (0° direction) was found to be lower than that perpendicular to the stretched direction (90° direction) above the temperature of primary dispersion (αa) for all polymers cited above. Below the temperature of an dispersion the E′ value of 0° direction is higher than that of 90° direction as expected from the anisotropy of modulus of the crystal. This fact leads us to the model that the crystalline region (C) and this amorphous region (A) are arranged mainly in series along the stretched direction and at the same time the C region should be more or less continuous along the 90° direction. The actual drawn sample is composed of many microfibrils as proved ł y the x‐ray small‐angle scattering. Those conditions imposed on the model should be satisfied even when many microfibrils are bound together into a fiber. This picture agrees with the structural model of hot‐drawn PE presented by Hosemann after its slight modification. Effects of cold drawing on the anisotropy of modulus were also surveyed.
On the Structure and Properties of Polyamides. XXVII. The Mechanism of Water Sorption in Polyamides
Authors: Puffr R. , Šebenda J.
Published: June 2010

The sorption and the desorption isotherms of water are described for several crystalline polyamides (nylons 2, 3, 6, 7, 8, 11), amorphous polyamides (poly‐C‐methylcaprolactam, terpolymer of caprolactam, aminoheptanoic acid and aminoundecanoic acid) and model amides (N‐ethyl acetamide, Y‐ethyl butyramide, N‐butyl capronamide) at 27°C., with amides also at 40 and 55°C. On the basis of our own as well as reported data (on sorption isotherms, heat balance of sorption, sorption heats, infrared absorption, nuclear magnetic resonance, mechanical properties of polyamide‐water systems), we propose the following mechanism for the sorption of water in polyamides (capillary condensation is not considered): In nylon 6, three molecules of water are sorbed on two neighboring amide groups in an accessible region. The first molecule forms a double H‐bonds between the CO groups (firmly bound water) and the other two molecules form H‐bonds between the CO and the NH groups (loosely bound water). It turns out that even in nylons 2 to 6, water is probably sorbed by this mechanism whereas in nylons 8 to 12 only one molecule of water is sorbed on two amide groups, probably as a firmly bound water. Nylon 7 stands somewhere between the two groups.
Influence of Thermodynamic Quality of a Solvent upon Non‐Newtonian Viscosity of Poly(methyl Methacrylate) Solutions
Authors: Quadrat O. , Bohdanecký M. , Munk P.
Published: June 2010

Unlike the monotonous decrease of both the reduced and intrinsic viscosity with the increase in shearing stress with polystyrene, polyisobutylene, and other polymers in thermodynamically good and poor solvents, the dependence of the viscosity on the shearing stress, with poly(methyl methacrylate) solutions in the vicinity of θ‐temperature, shows an anomalous course. Reduced viscosity at first decreases with the increase in shearing stress; at 50 to 150 dynes/cm.2 it reaches a minimum but thereafter rises. The effect disappears with infinite dilution. The increase of reduced viscosity with the increase in shearing stress is in connection with a great increase of the Huggins constant, which means a high molecular interaction. Since this behavior at θ temperature does not occur with other polymers, it seems to depend on the specific structure of poly(methyl methacrylate).
Diffusion in gels
Authors: Špaček P. , Kubín M.
Published: June 2010

A new method for the determination of diffusion as well as partition coefficients of low molecular weight substances in membranes of polymers was developed, based on the solution of Fick's equation with appropriate boundary conditions (both concentrations variable). On its basis D and k of dilute (0.05%) KCl solutions in swollen hydrophilic gels of different porosity were determined. From the temperature dependence of diffusion coefficients the activation energy of the process was computed and a simple model describing the structure of the heterogeneous membrane was proposed. The diffusion coefficients strongly depend on the structure of the system investigated.
Viscoelastic properties of single crystal mats of some polymers and polymer crystal obtained by radiation‐induced solid‐state polymerization
Authors: Takayanagi Motowo , Imada Kiyohisa , Nagai Akihiko , Tatsumi Tetsujiro , Matsuo Takaaki
Published: June 2010

Measurements of the tensile dynamic viscoelasticity have been made in the temperature range from −170°C. to near the melting temperature at 110 cps on the single crystal mats of linear polyethylene with different lamella thickness and trans‐1,4‐polybutadiene, and the polymer crystal of polytetraoxane prepared by the radiationinduced solid‐state polymerization of tetraoxane. Under the conditions of measurements, the stress applied is almost perpendicular to the molecular axis for the single crystal mat and parallel to the molecular axis for the polytetraoxane crystal. The crystalline absorption of the single crystal mat of linear polyethylene shifted to the high temperature side and increased its intensity with increasing lamella thickness. The single crystal mat of trans‐1,4‐polybutadiene showed the comparatively large primary absorption, which was almost eliminated by heat treatment. This phenomenon may be caused by the existence of loose loops in the sample of single crystal. Various absorptions of polyoxymethylene such as the crystalline and the low temperature secondary absorption, which was remarkable in the single crystal mat, almost completely vanished for the polytetraoxane crystal, and outstanding constancy of the dynamic modulus was attained close to the melting temperature 190°C.
Crystallization and ordering processes in polyhydrocarbons with chemically irregular chains
Authors: Platé N. A. , Kheu Tran , Shibaev V. P.
Published: June 2010

An x‐ray, electron microscope, and mechanical properties study was carried out on polyethylene, isotactic polypropylene, and trans‐1,4‐polyisoprene (gutta‐percha) with different degrees of chemical irregularity made by halogenation reaction of these regular polymers. The gradual distortion of chemical regularity causes a change in crystalline lattice parameters, degeneration of crystalline spherulitic structure, and simplification of supermolecular structures of the polymers investigated. The introduction of chemical irregularity is analogous to supercooling of a crystalline polymer with suitable change of mechanical properties and morphological forms of structures. In the case of gutta‐percha, chlorination in films also favors the α to β transition within the crystalline state. It has been found that stretching of vulcanized samples of chlorogutta‐percha at temperatures above its melting point proceeds with an essential change in internal energy and increase of entropy. A supposition has been made about the structure peculiarities of chlorogutta‐percha which permit the appearance of such an effect. A total picture of change of different parameters and properties is given from the point of view of gradual transformation of the stereoregular polymer to an irregular amorphous one.
Cyclic polymerization of N‐dimethacrylamides
Authors: Sokolova T. A. , Rudkovskaya G. D.
Published: June 2010

Monomer dimethacrylamides are polymerized on heating in bulk and in solution, yielding soluble and fusible polymers which contain practically no unsaturation. Similar polymers are obtained by partial thermal deamination of polymethacrylamides at 300°C. in vacuum. Infrared spectroscopy has shown that the polymers obtained by the polymerization of the monomer N‐substituted dimethacrylamides consist of fivermembered cycles (the region of carbonyl absorption 1700‐1790 cm.−1) linked by a bridge of two methylene groups. The polymers obtained by deamination of polymethacrylamides contain six‐membered cycles (carbonyl absorption in the range from 1680 to 1730 cm.−1) linked by one methylene group. This is confirmed by a comparison of the infrared spectra of the polymers and of model compounds: imides of succinic and glutaric acids. Dimethacrylamide is an exception, its polymerization yields a polymer consisting of 5‐membered cycles as well as 6‐membered ones. X‐ray analysis shows the polymer obtained by thermal deamination of polymethacrylamide to be oriented and highly crystalline. Some properties of the polymers obtained are described.
Kinetics and mechanism of acrylonitrile polymerization by p‐toluene sulfinic acid. I. Experimental
Authors: Amdur Shimon , Shavit Nehemia
Published: June 2010

p‐Toluene sulfinic acid (TSA) of a high degree of purity, halide free and low p‐toluene sulfonic acid (TOSA) content, was prepared. A cooled‐capillary dilatometer was constructed for the study of the bulk heterogeneous polymerization up to high conversions. Acids were found to show both cocatalytic and inhibitory activities, depending on their type and concentration. The bulk polymerization of acrylonitrile (AN) by TSA shows the usual autoacceleration, which was found however to be depressed or even eliminated by the addition of TSOA and other acids. An autoacceleration phenomenon was found in the solution polymerization of AN at 60°C. by TSA alone. In this case the addition of small amounts of TSOA eliminated the autoacceleration. On addition of TSOA to samples of constant TSA concentration, in bulk or in solution, the initial rate increases, reaches a maximum, and then decreases. A decrease in rate was also observed in the azo‐initiated bulk polymerization on addition of TSA + TSOA. Increasing the concentration of TSOA or H3PO4 in the bulk polymerization, at constant TSA concentration, leads to a lowering of molecular weight. The order of the polymerization with respect to TSA was found to be between 1.1 and 1.5, depending on the TSOA concentration. The results are explained by an enhancement of the TSA initiation through its interaction with a proton, and the role of a TSA‐proton complex in a retardation mechanism.
Phase separation during the formation of three‐dimensional polymers
Authors: Dušek K.
Published: June 2010

Phase separation during the formation of three‐dimensional polymers in the presence of inert diluents, by crosslinking of linear polymers, or by polymerization of multifunctional monomers, was treated under the assumption of thermodynamic equilibrium by using the Flory theory of swelling equilibria and rubber elasticity. The separation begins when the maximum swelling of the network in the diluent or diluent‐monomer mixture drops to the degree of dilution of the network; the two quantities remain equal even after separation of phases. The network formed in this way is a composite one. Relations have been derived for the dependence of composition and volume of the network phase upon initial conditions and degree of crosslinking or extent of polymerization. The results of calculations for binary and ternary model systems are discussed with respect to syneresis or formation of porous structures, as two possible modes of phase separation.
Rheo‐optical studies of high polymers. IX. A study of deformation process of low‐density polyethylene by simultaneous measurements of stress, strain, and infrared absorption
Authors: Onogi Shigeharu , Asada Tadahiro
Published: June 2010

As one of rheo‐optical methods to study the relation between structure and mechanical properties of high polymers, simultaneous measurement of the stress, strain, and IR absorption during the experiments involving stress relaxation and stretching at constant rate of strain has been developed. The IR absorbances measured with radiations, both unpolarized and polarized, for the crystalline bands near 725 cm. −1 of low‐density polyethylene can attain their equilibrium values in a time shorter than 1 sec. during the stress relaxation, being consistent with the results obtained by the dynamic birefringence method. In the case of stretching at a constant rate of strain, the orientation functions of crystallographic axes can be obtained as functions of strain from the dichroic ratio. The orientation function vs. strain curves and the corresponding stress‐strain curve for low‐density polyethylene film in the machine direction are divided into four regions according to the magnitude of strain. On the basis of comparison of these curves with each other and by employing the current model of folded chains, an interpretation has been given of the above four regions in the stress‐strain curve.
The pore structure of macroreticular ion exchange resins
Authors: Kun Kenneth A. , Kunin Robert
Published: June 2010

A series of new cation and anion exchange resins differing entirely from conventional homogeneous (microreticular) gels and having a rigid macroporous structure similar to those of conventional adsorbents are characterized. These ion exchangers have been designated as macroreticular ion exchange resins. A detailed analysis is made of the pore structure of the resins including pore size distribution, surface area, and electron micrographs. From these data a model of the physical structure is presented. The relationship between the physical structure and utility of these ion exchange resins is developed for various areas of application, including catalysis, adsorption from nonpolar solvents, and the adsorption of large molecules such as peptides and proteins. The effect of hydration upon the pore structure of several of the macroreticular ion exchange resins is critically evaluated also. During the course of hydration, the gel portion hydrates first and this is followed by the filling of the macroreticular pores. From these data one is able to ascertain the pore structure not only in the anhydrous state but also in aqueous media.
Vinyl chloride polymerization initiated by the interaction of organoaluminum compounds and various agents
Authors: Minsker K. S. , Sangalov Yu. A. , Razuwayev G. A.
Published: June 2010

Interactions of organic aluminum compounds and organic or inorganic halogen‐containing compounds (halogens, haloid alkyls, saturated or unsaturated chlorocarbons, metal halides, halogen anhydrides of organic acids) were used to polymerize vinyl chloride. Utilization of the foregoing reactions makes it possible to polymerize vinyl chloride at low temperatures (+20 to −50°C.). The polymerization process can be controlled by adjusting the reaction conditions of the initiating components. Furthermore, the combinations of organic titanium compounds and some of the previously mentioned chlorocarbons were also used as active initiators. The polymers which were synthesized possessed novel properties as well as those which are characteristic to poly(vinyl chloride).
A study of the formation of supermolecular order in polymeric solutions by means of low‐angle scattering of polarized light
Authors: Frenkel S. Ya. , Baranov V. G. , Volkov T. I.
Published: June 2010

A relatively simple device is described for studies of phase transitions in polymer solutions and films by means of low‐angle scattering of polarized light. The device differs from that described by Stein. It functions as a horizontal polarizing microscope, as a photodiffractometer, and as a photometer. A study was carried out of the structure formation in concentrated solutions of poly‐γ‐benzyl‐L‐glutamate with Mw = 105 in dioxane. At room temperature and in the absence of external fields a successive development of several levels of supermolecular order is observed. The structure formation starts with the spherulitic phase characterized by a cross‐shaped diffraction pattern. During their progressive growth the spherulites fill the volume of the solution and finally begin to collapse. This changes the scattering pattern to a circular one. The mechanical instability of this phase and the thermodynamic advantage of a parallel packing of rodlike particles leads to the appearance of an orientational order in the system with a rhombic‐shaped scattering pattern. The structure formation is completed with the development of a highly ordered liquid crystalline (cholesteric) phase characterized by a specific pattern similar to the x‐ray diffraction patterns of oriented crystalline polymers. A detailed interpretation of rhombic scattering pattern is presented based on an analysis of polarized light scattering from a system of noncoherent scattering elements with the shape of a rectangular parallelepiped. Expressions are derived connecting the shape and the size of the scattering pattern with the dimensions of a single scattering element, and with the optical properties of this element and of the supporting medium. The spherulitic growth habit in isotactic polypropylene solutions when subjected to cooling also has been studied. At temperatures below 100°C. the spherulites appear and the rate of their growth is dependent on the thermal history of the solution. Kinetic curves are obtained showing the existence of a “kinetic memory” in the system which is manifested by a pronounced acceleration of growth of the structure when the fusioncrystallization cycles are repeated.
Studies on phenolic resins. VII. The preparation of a new type of self‐crosslinking phenolic resin and the reaction mechanism of the crosslinking
Authors: Kumanotani Ju , Yoshikawa Toshio , Kubo Etsuji , Kawanishi Isamu , Okamura Takeshi
Published: June 2010

A new type of a phenolic self‐crosslinking resin was prepared by the oxidation of the hydroquinone–phenol formaldehyde resins with chloric acid. The chemical behaviors of the resin in the process of self‐curing occurred by heating were followed by DTA and the infrared spectral analysis. Some physical properties such as glass transition temperature and the extent of crosslinking were examined for the cured resins by the swinging beam method and the solvent extraction method, respectively, and the excellent thermal rigidity of the cured resins was compared with that of the conventional phenolic resins cured with hexamethylenetetramine. The radical reaction mechanism in the self‐crosslinking of the resin is proposed from the results obtained in the reactions of p‐benzo‐quinone with some model phenolic compounds and that obtained in the observation of ESR spectrum of the quinhydrone system.
Relations between crystalline structure and dielectric properties of polyethylene
Authors: Booij H. C.
Published: June 2010

Slightly oxidized polyethylenes show dielectric loss factor–frequency curves exhibiting three maxima. The magnitude of the α‐maximum at low frequencies is proportional to the oxygen content and to the weight of crystalline material per cc. The frequency of this maximum is in general higher as the degree of branching of the polyethylene increases. The frequency of the α maximum of solutions of n‐ketones in polyethylenes decreases with the length of the ketone and increases with the degree of branching of the polyethylene. A theory was developed which quantitatively describes the frequency of this α maximum as a function of the temperature, the chain length of the ketone, the average crystalline density of the polyethylene, and a quantity which is related to the twist energy per unit length of the chain. This theory can be experimentally used in to find a value for the length of the molecules participating in the α process in oxidized polyethylenes. The values found are about equal to the crystallite lengths, or the lamella thicknesses, of the polyethylenes.
Fractionation of polymers by crystallization from solutions. II
Authors: Pennings A. J.
Published: June 2010

The fractionation of polyethylene and polypropylene is carried out by establishing equilibrium between a polymer solution and the solid polymer. This procedure involves crystallization kinetics, crystal morphology, surface effects, and the formation of solid solutions. If the solution is stirred, the polymer forms thin fibrous crystals which adhere to the stirrer as a loose fabric. The experimental data on the precipitation and extraction of polyethylene in various solvents and of polypropylene indicate that fractionation takes place in the low as well as in the high molecular weight range. The components with a very high molecular weight crystallize first. The method appears to be especially suitable for the separation of branched from linear polymers, atactic from isotactic stereoisomers, and mixtures of polymers which differ considerably in crystallization rate. Thus, 46% pure polypropylene, 7% rubber, 1% pure polyethylene, in addition to block copolymers varying in structure, could be isolated from an ethylene‐propylene block copolymer.
Procédé Amelioré de Fractionnement des Polymères sur Support Inerte (Polypropylène, Polyéthylène, chlorure de Polyvinyle)
Authors: Ferrier Jean
Published: June 2010

A two‐stage process is described: the first, stage is a fractional precipitation, the second a fractional dissolution. Preciptiation is carried out in a column containing glass beads and functioning under a temperature gradient. The polymer is washed with a poor solvent and subsequently a continuous linearly programed dissolution by a solvent‐preciptiant system takes place at constant temperature. This procedure has been applied successfully to polypropylene, polyethylene, and poly(vinly chloride). Reproductible results have been obtained independent of tacticity and cristallinity in every case. The separation obtained is very satisfactory.
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

Dilatometric, 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.