bluuebunny/crossref_metadata_2025 huggingface dataset:
ChemInform Abstract: Intramolecular Electron Transfer Between Terminal 1,4‐Dimethoxybenzene Units in Radical Cations with a [2.2](1,4)Naphthalenophane, [2.2](1,4)Anthracenophane, and Pentacene Skeleton.
Authors: WARTINI A. R. , STAAB H. A. , NEUGEBAUER F. A.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Regioselectivity of the Enzymatic Transgalactosidation of D‐ and L‐Xylose Catalyzed by β‐Galactosidases.
Authors: MONTERO E. , ALONSO J. , CANADA F. J. , FERNANDEZ‐MAYORALAS A. , MARTIN‐LOMAS M.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Low‐Valence Palladium Complexes: Stoichiometric Reactions and Catalysis
Authors: MOISEEV I. I. , STROMNOVA T. A. , VARGAFTIK M. N.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Anomalies and the Discovery of the Imidazolinone Herbicides
Authors: LOS M.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Enzymatic Aspects of Isoprenoid Chain Elongation
Authors: OGURA K. , KOYAMA T.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis of Carbohydrate‐Containing Dendrimers. Part 6. Synthesis and Biological Evaluation of α‐D‐Mannopyranoside‐Containing Dendrimers.
Authors: ASHTON P. R. , HOUNSELL E. F. , JAYARAMAN N. , NILSEN T. M. , SPENCER N. , STODDARD J. F. , YOUNG M.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Mode of Antibacterial Action of Retrochalcones from Glycyrrhiza inflata.
Authors: HARAGUCHI H. , TANIMOTO K. , TAMURA Y. , MIZUTANI K. , KINOSHITA T.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A Naphthoquinone from Newbouldia laevis Roots.
Authors: GAFNER S. , WOLFENDER J.‐L. , NIANGA M. , HOSTETTMANN K.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Asymmetric Syntheses of Panclicins A‐E via [2 + 2] Cycloaddition of Alkyl(trimethylsilyl)ketenes to a β‐Silyloxyaldehyde.
Authors: KOCIENSKI P. J. , PELOTIER B. , PONS J.‐M. , PRIDEAUX H.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: The Yellow Color of Silver‐Containing Zeolite A.
Authors: SEIFERT R. , KUNZMANN A. , CALZAFERRI G.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Band Structure Theory of Magnetism in 3d‐4f Compounds
Authors: RICHTER M.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Starting from the Zintl‐Concept: Syntheses and Crystal Structures of K2Ba3Sb4 and KBa4Sb3O.
Authors: Eisenmann Brigitte , Gieck Christine , Roessler Ute
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Association study between antipsychotic‐induced restless legs syndrome and polymorphisms of monoamine oxidase genes in schizophrenia
Authors: Kang Seung‐Gul , Park Young‐Min , Choi Jung‐Eun , Lim Se‐Won , Lee Heon‐Jeong , Lee Seung‐Hwan , Kim Yong‐Ku , Kim Seung‐Hyun , Cho Sung Nam , Kim Leen
Published: June 2010

Objective

This study aimed to investigate whether the monoamine oxidase (MAO) A and B genes are associated with antipsychotic‐induced restless legs syndrome (RLS) in schizophrenia.

Methods

We assessed antipsychotic‐induced RLS symptoms in 190 Korean schizophrenic patients and divided the subjects into two groups: those with RLS symptoms (n = 96) and those without RLS symptoms (n = 94). Genotyping was performed for the variable number of tandem repeat (VNTR) polymorphism of the MAOA gene and A644G polymorphism of the MAOB gene.

Results

There was no significant difference in the genotype and allele frequencies of all polymorphisms investigated between these two groups. However, the result of global haplotype analysis showed a significant difference in haplotype frequencies between male subjects with and without RLS symptoms (p = 0.013). The interaction between two polymorphisms had a significant effect on the RLS scores of both male (p = 0.047) and female (p = 0.028) patients.

Conclusions

These data do not suggest that the MAOA gene VNTR and MAOB gene A644G polymorphisms are associated with antipsychotic‐induced RLS symptoms in schizophrenia. However, we found that the haplotype frequencies differed between the male schizophrenic patients with and without RLS symptom and the interaction between the two polymorphisms had a significant influence on the RLS scores of patients with schizophrenia. Copyright © 2010 John Wiley & Sons, Ltd.
Fundamental Measurements in Online Polymerization Reaction Monitoring and Control with a Focus on ACOMP
Authors: Alb Alina M. , Reed Wayne F.
Published: June 2010

Fundamental measurements in online polymerization reaction monitoring and control seek to avoid empirical and inferential models in data interpretation. One such approach making use of multiple detectors is automatic continuous online monitoring of polymerization reactions (ACOMP), wherein a continuous reactor stream is automatically, continuously diluted and conditioned to where measurements reflect intrinsic particle properties and not the interactions that can dominate measurements in concentrated media. Examples where dilute regime measurements are needed include static and dynamic light scattering, and reduced viscosity. This review focuses on ACOMP to illustrate a number of reaction contexts where fundamental measurements are used to gain a comprehensive picture of reaction characteristics.

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The tensile properties of electrospun nylon 6 single nanofibers
Authors: Bazbouz Mohamed Basel , Stylios George K.
Published: June 2010

In this article, we have aimed to mechanically characterize the nylon 6 single nanofiber and nanofiber mats. We have started by providing a critical review of the developed mechanical characterization testing methods of single nanofiber. It has been found that the tensile test method provides information about the mechanical properties of the nanofiber such as tensile strength, elastic modulus and strain at break. We have carried out a tensile test for nanofiber/composite MWCNTs nanofiber mats to further characterize the effect of the MWCNTs filling fiber architecture. In addition, we have designed and implemented a novel simple laboratory set‐up for performing tensile test of single nanofibers. As a result, we have established the stress–strain curve for single nylon 6 nanofibers allowing us to define the tensile strength, axial tensile modulus and ultimate strain of this nanofiber. The compared values of the tensile strength, axial modulus and ultimate strain for nylon 6 nanofiber with those of conventional nylon 6 microfiber have indicated that some of the nylon 6 nanofiber molecule chains have not been oriented well along the nanofiber axis during electrospinning and through the alignment mechanism. Finally, we have explained how we can improve the mechanical properties of nylon 6 nanofibers and discussed how to overcome the tensile testing challenges of single nanofibers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1719–1731, 2010
Two‐phase crystallization kinetics of syndiotactic polystyrene
Authors: Sorrentino Andrea , Pantani Roberto , Titomanlio Giuseppe
Published: June 2010

In this work, a two phase crystallization model based on the extension of the Kolmogoroff approach was proposed and verified by comparison with experimental isothermal and nonisothermal crystallization data of Syndiotactic Polystyrene (sPS) in a very wide range of cooling rates, up to 600 °C/s. To investigate the effects of high cooling rate on the sPS crystalline structure, a homemade apparatus was adopted. The morphology in solid samples was analyzed by densitometry, IR spectroscopy, and X‐rays diffraction. The coupling of these techniques allows the determination of the fractions of different crystalline phases. In agreement with melt‐crystallization studies of sPS proposed by different authors, either α and β forms could be produced depending on the thermal history of the sample. Results show that the stable β form is favored for specimens solidified at higher temperature or under low cooling rates, whereas α and mesomorphic forms are favoured at low temperature or high cooling rates. The proposed multiphase crystallization kinetics model successfully described all the range of experimental data. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1757–1766, 2010
Temperature dependence of orientation birefringence of polymers in the glassy and rubbery states
Authors: Andrews R. D. , Hammack T. J.
Published: June 2010

The temperature dependence of orientation birefringence has been measured for several different polymers, by producing samples with a fixed degree of orientation by mechanical stretching, and varying the temperature. The following three polymers were studied: polystyrene, poly (methyl acrylate), and poly(methyl methacrylate)—the last in both atactic and stereospecific forms. These all have negative orientation birefringence at room temperature. Measurements were carried out in a range of temperatures below the glass transition temperature, except for poly(methyl acrylate) which was crosslinked. The curves obtained for the different polymers showed considerable differences in form; they were reversible in regard to temperature cycling, and showed no appreciable time effects. Polystyrene showed little change in its orientation birefringence with temperature. The other polymers showed appreciable changes with temperature, and an actual change of sign of the birefringence from negative to positive with increasing temperature. The crossover temperature was near the glass transition temperature for the various stereo forms of PMMA, and measurement of this crossover temperature might therefore provide a fairly accurate method for determining the stereo composition of a PMMA sample. However, the crossover temperature is considerably above Tg in the case of PMA. We believe that these curves reflect thermal motions of the molecular groups with polarizability anisotropy (such as the phenyl and eater side groups) whose orientation gives rise to the birefringence. The small change is the case of polystyrene is undoubtedly a consequence of the rigidity of the phenyl ring and the steric hindrance of its immediate environment. These results may also reflect chain backbone motions, and other effects, in an indirect way. The theory and experimental data for a complete interpretation of these results is not yet available. However, some of the evident consequences of the present findings are discussed.
Dynamic birefringence of several high polymers
Authors: Yamada R. , Hayashi C. , Onogi S. , Horio M.
Published: June 2010

The complex strain‐optical coefficient, complex stress‐optical coefficient, complex modulus of elasticity and the corresponding loss tangent of phase angles between the stress, strain and birefringence have been measured for several high polymers in the frequency range from 0.001 to 10 cycles/sec. Frequency and temperature dependences of the dynamic optical properties of vulcanized Hevea rubber are very similar to those of the dynamic mechanical properties. On the other hand, the dynamic optical properties of polyethylene and polypropylene show remarkable dispersions in the above frequency range. The dynamic optical behavior of these three materials are very typical and are quite different from each other. The differences have been explained by considering different frequency dependences of three kinds of deformation mechanism, namely, orientation of molecules in amorphous region, deformation of spherulites, and orientation of crystals.
Morphological and rheological studies of polyethylene by light scattering
Authors: Moore Robert S. , Matsuoka Shiro
Published: June 2010

The technique of photographic light scattering was employed to study films of medium and high molecular weight linear polyethylene. Results on the high molecular weight polymer show that secondary crystallization is severely restricted, that oxidation induces further crystallization, and that annealing may lead to tilted chain lamellae. Results of experiments conducted on films of the medium molecular weight polymer while subjected to tensile stress indicate that spherulite deformation occurs at very small strains in agreement with proposed theories.
Thermal analysis of polyurethane elastomers
Authors: Slade Philip E. , Jenkins Lloyd T.
Published: June 2010

Differential thermal analysis and thermogravimetric analysis were used to evaluate the thermal properties of several types of polyurethane elastomers. The composition of the polymers investigated was changed by varying the substrate, or soft segment, diisocyanate and extender. The data indicated that within the limits of the compositions under study, polyurethanes were thermally stable to their melting points, however, above the melt they were susceptible to oxidation unless stabilized by the addition of an antioxidant. On the differential thermograms the absence of a pronounced endothermic peak at the melting point, characteristic of non‐crystalline polymers, was observed. The decomposition of polymers made with 4,4′‐diphenylmethane diisocyanate (MDI) occurred above 400°C. and was at least a two‐step process, while the decomposition of polymers containing toluene diisocyanate (TDI) occurred below 400°C. and appeared to be a one‐step reaction.
A differential thermal analysis study of the effects of thermal history on polyethylene
Authors: Holden H. W.
Published: June 2010

The melting and crystallization behavior of polyethylene samples has been investigated by differential thermal analysis (DTA), with special emphasis on the effects of thermal conditioning on the crystalline state of the sample. Techniques are outlined for impressing a wide variety of thermal histories on the sample in the DTA cell. In particular, the use of an annealing procedure is shown to provide a significant evaluation of the extrapolated value of the equilibrium melting temperature, combined with a rapidity not possible by the dilatometric method. Theoretical implications of the various procedures and results are briefly discussed. Critical examination of the fine structure observed in the melting thermograms leads to the conclusion that under certain conditions crystallites originating from both heterogeneous and homogeneous nucleation can be detected. The temperature rise associated with very fast crystallization is considered to influence the subsequent melting temperature more significantly than the effects of re‐crystallization during the actual melting cycle. Some illustrations are given of the general usefulness of the conditioning procedures in clarifying phenomena observed with various samples.
Kalorimetrische Messungen von Wärmeeffekten bei Verstreckung
Authors: Müller F. H. , Weimann N.
Published: June 2010

Heat effects and the work in stretching a polycarbonate are measured in a wide range of stretching rates and at two different temperatures. Conclusions are drawn on the enthalpy increase during the stretching process. Indirect conclusions on the entropy variation during stretching seem to be possible. The effect of temperature balance is confirmed and the strain relaxation of the stretched material seems also to be coupled with heat production.
Sedimentation velocity determinations of molecular weight distributions
Authors: Blair James E.
Published: June 2010

In the sedimentation velocity experiment, the ultracentrifuge fractionates the molecules according to molecular weight, along the radial axis in the rotating cell. The boundary gradient curve measured during the experiment can be transformed into an apparent distribution of sedimentation coefficients, which can twined to determine the true sediment at ion coefficient distribution by the introduction of a number of corrections. This true distribution can often be converted into the weight distribution of molecular weights. This paper discusses the current views of each of these corrections, which account for the effects of diffusion, hydrostatic pressure, concentration, and the time needed to attain operating speed. The sensitivity of the resultant molecular weight distribution to several parameters is indicated for a polystyrene sample.
Effect of component removal upon the porous structure of the cell wall of wood
Authors: Stone J. E. , Scallan A. M.
Published: June 2010

It has been shown by nitrogen adsorption that the removal of lignin and hemicellulose from the middle lamella and cell wall of spruce wood produces pores with a median size in the 20–40 A. range throughout the dissolution process. During both kraft and sulfite pulping, these pores have a total volume which from 90–100% yield equals, from 55–90% yield exceeds, and below 55% yield is less than, the volume of material removed from the wall. The results therefore indicate a swelling of the wall at intermediate yields followed by a contraction below the initial dimensions towards the end of pulping. In accordance with a previously postulated theory of cell‐wall structure based on a multilamellur model, the pores produced by the dissolution of wood components are the slit‐like spaces between adjacent lamellae. Specific surface measurements show that, on this model, the cell wall of water‐swollen wood consists of about 5 lamellae, which subdivide into a total of about 350 lamellae each 35 A. thick at the point of maximum swelling (65–70% yield). Thereafter, towards lower yields, the lamellae start to reaggregate. This technique applied to groundwood pulp shows that the process of splitting the wall into layers may be accomplished to some extent by purely mechanical action.
A new technique for observing light‐scattering patterns from polymer films
Authors: Moore Robert S. , Gieniewski Chester
Published: June 2010

A now, extremely Simple, technique for visually observing light scattering from polymer films is presented. The technique employs a polychromatic divergent light source, in some cases with no polarizers, as the entire apparatus. It is shown that patterns characteristic of scattering from the spherulites and the rings, including multi‐ple‐Order scattering from the latter, can be observed by this method. Applications to monitoring of spherulite size during polymer processing are briefly discussed. It is shown that by simple collimation the method can be extended to photographic recording of scattering patterns and that after determination of the effective wavelength of the source the patterns can be quantitatively analyzed. It is demonstrated that wide angle scattering patterns comparable to those obtained with a laser can be obtained in comparatively short exposure times.
Approximate theory for diffuse first‐order phase transitions
Authors: Tobolsky A. V. , Canter N. H.
Published: June 2010

The phenomenon of diffuse phase transitions occurs widely in simple inorganic and organic systems, such as the solid‐solid transitions in ammonium chloride and in methane. It is known that in a finite temperature interval centered around the transition temperature, both the low temperature phase A and the high temperature phase B coexist. The most renowned manifestations of this phenomenon are the unusual specific heat curve (the lambda point anomaly); the appearance of x‐ray lines of two distinct phases, A and B, in the temperature interval of transition; and a gradual rather than a discontinuous change of volume in the transition interval. A statistical thermodynamic model of the Ising type was developed which describes all of these seemingly diverse phenomena in a unified and quantitative manner. The central feature of the theory is that it postulates the existence of a geometrically simple boundary phase which coexists with phase A and phase B. The theory introduces only a simple constant to describe a diversity of experimental results, the constant being the free energy of formation of the boundary phase, denoted as ΔGk. The theory was applied to the diffuse phase transitions in such solids as (NH4)2SiF6, Ag2H3IO6, KH2AsO4, KH2PO4, NH4Cl, and CH4, as well as to the diffuse melting of polymers, such as polyethylene, and to the helix‐coil transition in polypeptides and in polynucleotides. By use of a single constant, ΔGk, for each substance a very good fit of the experimental heat capacities versus temperature is generated for (NH4)2SiF6, Ag2H3IO6, KH2PO4, KH2Aso4, NH4Cl, and CH4. For diffuse solid‐solid transitions, the width of the x‐ray lines in the coexistence regions was predicted‐ Since such experimental data are not yet available, this prediction is offered as a very severe experimental test of the theory. In this paper we present very simple approximate equations of the Gaussian form which represent an excellent fit to the exact theory and to experiment.
A complex plane analysis of α‐dispersions in some polymer systems
Authors: Havriliak S. , Negami S.
Published: June 2010

The α‐dispersion in many polymer systems is the process to be associated with the glass transition temperature where many physical properties undergo drastic changes. We have measured and analyzed the complex dielectric behavior of the α‐dispersions for five polymers [i.e., polycarbonate and polyisophthalate esters of bisphenol A, isotactic poly‐(methyl methacrylate), poly(methyl acrylate), and a copolymer of phenyl methacrylate and acrylonitrile] and have found that the usual methods of analysis cannot be used to represent the data. However, it is possible to represent the relaxation process as the sum of two dispersions but there is no evidence to support this contention. An empirical expression is proposed to represent the data. This expression which takes the form of

appears to be a general representation for the three known dispersions, i.e., Debye, circular arc, and skewed semicircle. The complex dielectric constants calculated with the aid of this expression and the parameters for each polymer system which was determined graphically were found to be in excellent agreement with the experimental complex dielectric constants. This method of representation was extended to sixteen α‐dispersions reported in the literature always with excellent results.
Multiple transitions in polycarbonate
Authors: Matsuoka S. , Ishida Y.
Published: June 2010

Two kinds of dielectric absorptions due to motion of carbonate groups in polycarbonate were observed. In the primary transition region near 150°C, the shape of e′ versus log frequency curve is little affected by a temperature change, while it becomes more widely spread when the polymer is partially crystallized. In contrast, in the secondary transition region near −120°C., the shape of e′ versus log frequency curve is greatly affected by a temperature change, but it is not sensitive to the crystallinity. By using a conclusion drawn from a separate study that an increase in width of the loss curve is a manifestation of segments that are constrained, it is suggested here that the secondary transition involves local motions which persist in a highly restricted framework of glassy polymer chains and that such restriction becomes more pronounced at lower temperatures. Results from the PVT and x‐ray studies are consistent with the above concept, i.e., glassy polymers in general contain enough space so that limited local motions arc allowed that give rise to the low temperature transition.
The high temperature (T > Tg) amorphous transition in atactic polystyrene
Authors: Boyer Raymond F.
Published: June 2010

We first summarize available experimental evidence indicating the existence of a second‐order transition or relaxation region in atactic polystyrene at 60 to 100°C. above Tg. It increases from 137°C. at a molecular weight of 3000 to 192°C. at a molecular weight of 392,000. It appears in such diverse measurements as thermal expansion, heat capacity, x‐ray studies, deformation‐temperature plots, dynamic mechanical loss, stress relaxation, melt viscosity, and DTA. It may not appear if the test method is a very slow one, presumably because it merges with Tg. We ascribe this phenomenon to an ability of the entire polymer chain to act as a unit because of the available free volume and enhanced chain mobility at elevated temperatures. This is consistent with the fact that this transition shows up in melt viscosity studies and is completely suppressed by crosslinking. Since this represents a change from one liquid state to another, we designate this transition as Tl,l.
Nuclear magnetic resonance study of molecular motions in some crystalline polymers
Authors: Iwayanagi Shigeo , Sakurai Ikuko
Published: June 2010

Nuclear magnetic resonance linewidth studies are made concerning the molecular motions in crystalline polymers moh as polyethylene, polytetrafluoroethylene, and trans‐1,4‐polybutadiene. (1) The γ (local mode) relaxation of polyethylene is studied based on the temperature variation of mobile fraction. The range of the β (primary) dispersion of linear polyethylene is shown to spread far wider than that of branched polyethylene, whereas its lower limit (Tg−) is the same for the two. (2) Concerning polytetrafluoroethylene, a third NMR component is found in addition to narrow and broad‐line components, and the third phase of molecular aggregation is assumed to be intermediate between the amorphous and crystalline phases. The notion of the intermediate phase (an array of rodlike molecules) is instrumental in clarifying the complicated viscoelastie behavior by admitting two glass transitions in the polymer. (3) At the solid‐phase transition of trans‐1,4‐polybutadiene, a huge‐scale motional narrowing of the NMR absorption line takes place, indicating the onset of rodlike rotation of the molecules belonging to the crystalline phase. Above the phase transition temperature, the polymer crystal is “plastic”.
Rheo‐optical studies of the deformation of crystalline polymers
Authors: Stein R. S.
Published: June 2010

The deformation of a polycrystalline polymer must be examined in terms of the changes in morphology, texture, crystalline structure, and chain conformation. The understanding of the dynamic mechanical properties requires the specification of the rates of these changes. Optical techniques may be employed for this purpose. Dynamic x‐ray and dynamic infrared dichroism diffraction serve to define the rate of crystal orientation. Dynamic light scattering characterizes changes in the crystalline superstructure while dynamic birefringence characterizes the total orientation of crystalline and amorphous regions. A direct measure of amorphous orientation rate may be attempted by introducing a dye or chromophoric group into the amorphous regions and measuring its dynamic dichroism. In general, each of these dynamic observables may be resolved into a real and imaginary part (in and out‐of‐phase with strain). The results of measurements of these along with dynamic modulus measurements are discussed in an effort to present a consistent molecular and structural interpretation of mechanical behavior.
Effects of molecular weight and concentration on flow properties of concentrated polymer solutions
Authors: Onogi Shigeharu , Kimura Shigezo , Kato Takashi , Masuda Toshiro , Miyanaga Nobuyuki
Published: June 2010

Molecular weight (M) and concentration (c) dependencies of the viscosity were measured over wide ranges of M and c for concentrated solutions of linear and branched Poly(vinyl acetate) (PVAc) as well as of polystyrene (PS) in good and poor solvents, and the effect of branching and solvent on the flow properties was studied. The log η versus log M and log η versus log c curves for a given system can be superposed by the shift along the abscissa, giving smooth master curves. From the shift factors the ratio of the two exponents α and β, which appears in the following viscosity equation, can be evaluated:

where η is the viscosity, p is the density of the solution, and K is a constant at constant temperature. The evaluated values of β/α for the several systems studied here ranged from 0.54 to 0.72. The log η versus log M curves cannot always be approximated by two straight lines, and therefore it was proposed to determine this critical molecular weight Mc an the lowest molecular weight above which the viscosity becomes proportional to M3.4 or M3.5. Then, the viscosity at Mc is constant independent of c, and the relation between Mc and c is given by (cp)Mβ/α = constant. The experimental values of β/α were compared with the theoretical values given by Bueche and Onogi et al.
Secondary (β) Relaxation Process of Alkaline Polycaprolactam Swollen by Low Molecular Weight Substances
Authors: Kolařík J. , Janáček J.
Published: June 2010

By using the method of free torsion vibrations, a detailed dependence was determined of the temperature position and the height of the secondary (β) loss maximum of alkali‐polymerized polycaprolactam upon the concentration of water in the range of 0 < PA < 1.3, where PA is the number of moles of water per mole of monomer units of the portions accessible to the sorption of water. The increase in the secondary loss maximum and the decrease in the height of the low‐temperature loss maximum due to the effect of water in the concentration range 0 < PA < 0.5 is interpreted as consequence of a transformation of the corresponding relaxation processes; subsequent increase in the water content then exhibits only little influence on the height of both the maxima. The β relaxation process is attributed to kinetic units containing amide groups which, owing to interaction with molecules of water, are more firmly bonded to neighboring molecules than the amide groups of a dry polymer. The secondary loss maximum arises also because of the effect of caprolactam monomer and of some low molecular weight amides, being markedly shifted to higher temperatures with the decreasing molecular weight of the amide.
A light‐scattering study of the molecular parameters of polycaprolactam
Authors: Tuzar Z. , Kratochvíl P. , Bohdanecký M.
Published: June 2010

This paper describes a study of dilute solutions of polycaprolactam in mixed solvents TFP‐H2O‐LiCl with the objective of finding the most convenient solvent for determining the molecular weight of polyamides by the light‐scattering method. Selective adsorption of both TFP and LiCl on the polyamide has been proved and quantitatively determined. The adsorption of TFP decreases the measured value of molecular weight, whereas that of LiCl increases it. A composition has been found (TFP‐10% H2O‐0.1M LiCl) in which the two effects exactly compensate. In this mixed solvent 24 fractions of hydrolytic and alkaline polycaprolactams were measured in a range Mw = 9 × 1033 to 3.5 × 105. The same solvent and m‐cresol have also been selected for measuring the intrinsic viscosities and determining the constants of the Mark‐Houwink equation.
Specific polymerization of vinylpyridinium salts. Polymerization on macromolecular “matrices”
Authors: Kabanov V. A. , Aliev K. V. , Kargina O. V. , Patrikeeva T. I. , Kargin V. A.
Published: June 2010

4‐Vinylpyridinium salts could be spontaneously polymerized in organic and water media by unusual ionic mechanism. The growing active species were characterized with high chemical specificity. The growing chain end being intramolecular ionic pair (zwitterion) was able to add only the molecules of monomeric vinylpyridinium salt and does not react with other vinyl monomers, including vinylpyridine. The reaction described was used for polymerization of 4‐vinylpyridine on macromolecules of polystyrene sulfonic acid in water and in organic solvent. The chains of strong polyacid were operating as activating “matrices,” which adsorbed, neutralized, and polymerized strictly stoichiometric amount of monomer molecules. The morphology of polymerization products was studied with electron microscopy.
Cyclo‐ and cyclized diene polymers. VIII. Cyclization of polybutadienes and ir spectra of cyclized polybutadiene
Authors: Kössler I. , Vodehnal J. , Štolka M. , Kálal J. , Hartlová E.
Published: June 2010

Cyclization of cis‐1, 4 and trans‐1, 4‐polybutadiene as of poly (2,3‐dimethyl butadiene‐1,3) was carried out with H2S4 as the cyclization agent. The decrease of the original unsaturation as well as of total unsaturation were measured with IR spectroscopy and the iodine monochloride method, respectively. The kinetics of cyclization were measured and evaluated with an analog computer. Both methods indicate the length of cyclic segments as 25–45 cycles. In the case of poly(2,3‐dimethyl butadiene‐1,3) only monocycles are formed. Some indications of secondary reactions, including isomerization, accompanying the eyclization were given by analyses of IR spectra and chemical analysis.
Growth reaction in the radical polymerization of chloroprene
Authors: Hrabàk F. , Bezděk M. , Hynkovà V. , Pelzbauer Z.
Published: June 2010

The effects of solvent, molecular weight regulator, and concentration of initiator and emulsifier on the polymerization rate of chloroprene in the latex particle was studied. By a modification in the method for the determination of the latex particle size by means of soap sorption, errors of conductometric titration due to the liberation of hydrochloric acid and dilution of latex were reduced. The found data were used to calculate the velocity constant of the growth reaction of chloroprene and its temperature dependence in the range of 10–35°C.
Study of the solution properties of linear and grafted polyurethanes
Authors: Beachell H. C. , Blumstein Rita
Published: June 2010

A high molecular weight linear polyurethane was prepared by condensation of tolylene‐2,4‐diisocyanate with ethylene glycol. Variable amounts of reactive side‐groups, such as the acrylyl and the ethylacrylate groups were introduced and the partially substituted N‐acrylyl and N‐ethyl acrylate polyurethanes were copolymerized in solution with methyl methacrylate, methyl acrylate, and styrene, using benzoyl peroxide as free‐radical initiator. The copolymers obtained had variable amounts of branches grafted onto the linear polyurethane backbone chain. These were isolated from the copolymer‐homopolymer mixtures by fractional precipitation. After fractionation the initial polyurethane was characterized by viscosity and light scattering. The configuration of the copolymers poly(urethane‐g‐methyl methacrylate) was found to depend on the number and molecular weight of the branches, the influence of the latter being particularly striking.
Polymerization of α‐methacrolein and the structure of the polymers
Authors: Andreeva I. V. , Koton M. M. , Getmanchuk Yu. P. , Madorsikaya L. Ya. , Pokrovskii E. I. , Koltsov A. I.
Published: June 2010

A high molecular weight poly(α‐methylacrolein) was obtaiiied with a yield of about 100% in the presence of a redox system and its strncture was investigated. It was established that the intrinsic viscosity of the polymers increases during the polymerization. It was shown that high molecular weight. poly(α‐methylacrolein) obtained with K2S2‐O2/AgNO3 contains not only free aldehyde groups but also the seniiacetal‐ether ones. The polymerization of α‐methyl‐ and α‐ethylacrolein was conducted with sodium naphthalene and trityl sodium. The structure of the polymers obtained was investigated by the following methods: oxinlation, ozonization, hydrogenation, oxidation with perbenzoic acid, and by PAIR and infrared spectroscopy. The dependence of the resulting structure on the temperature of the polymerization was established. It was shown that when the polymerization was conducted below 0°C. the polymers contained mainly coildensed tetrahydropyran cycles. At 0°C. and above the polymerization rate is changed, and the structure of the polymers is changed according to the data of chemical analysis, the formation of lactone structure being observed. Some considerations on the mechanism of the polymerization are given.
Alternative procedures for equilibrium determinations in the ultracentrifuge
Authors: Charlwood P. A.
Published: June 2010

Procedures have been described which enable solute concentrations in ultracentrifugal equilibrium to be evaluated more directly than hitherto. The first two variations, quite general in application, involve allowing a layer of solvent to flow on to solution and then following the subsequent rise in concentration of solute in the region just below the meniscus. The observations are made with Rayleigh interference optics. These methods have been tested with substances ranging in size from sucrose to γ‐globulin, and good agreement obtained with accepted molecular weights. Alternative procedures, which depend on increasing the rotor speed after equilibrium is reached, and observing the fall in concentration at the meniscus, are more critically dependent on base‐line reproducibility, but a satisfactory method has been found which is applicable to proteins of molecular weight down to 10,000 or even lower. The validity of this method has been confirmed by means of albumin and γ‐globulin. Not only have procedures for obtaining molecular weights been simplified, but the new techniques can be operated so as to reduce the time taken to reach equilibrium.
Effect of solvent and metal on the formation equilibria of naphthalene and diphenyl anion radical
Authors: Shatenshtein A. I. , Petrov E. S. , Yakovleva E. A.
Published: June 2010

The anion polymerization process is affected by the solvent and the counterion. A study has been made of the quantitative aspects of this effect using as a model reaction the formation of aromatic anion radicals in various ethers. The solvating capacity of the ethers with respect to alkali metal cations has been compared. The stability of the solvate complexes is due more to steric factors than to the electron donor and dielectric properties of the solvent or the polarity of its molecules. The heat of solvation of the cation contributes considerably to the energetics of anion‐radical formation. Therefore the structure of the solvent molecules strongly affects the thermodynamic parameters of the reaction. The solvation mechanism and its role in the ion association are discussed.
Entmischungseffekte in Hochmolekularen Lösungen
Authors: Rehage G. , Möller D.
Published: June 2010

Curves of phase equilibria of binary liquid systems at constant pressure are usually obtained from measurements of the cloud points. For high polymer solutions of a poly‐disperse polymer the cloud‐point curve alone is insufficient to describe the phase separation. This could be demonstrated by means of diffusion measurements in the polys‐tyrene‐cyclohexane system that show, below 28°C., a miscibility gap. Therefore, phenomena of phase separation have been examined more closely for this system. Besides cloud‐point curves, phase equilibria have also been measured as a function of the overall concentration, and it was found that the phase equilibrium curves shift with the overall concentration. Generally these curves are not closed. One branch of the equilibrium curve ends at the cloud point of the primary solution; the other one terminates freely. Only when the overall concentration corresponds to the critical concentration is a closed curve of phase separation obtained. The critical point is shifted with respect to the maximum of the cloud point curve to higher concentrations of polymer and is located at lower temperature. The location of the critical point can be derived from the determinations of phase equilibria by osmotic and diffusion measurements, from the volume ratio of the coexisting phases, and from the shape of the cloud‐point curves. The results can be interpreted on the basis of a model of a three‐component system, the solvent, and two polymer species of the same homologous series.
Polymerization by transition metal derivatives. IV. Investigations on the mechanism of butadiene polymerization by rhodium salts
Authors: Dauby R. , Dawans F. , Teyssié Ph.
Published: June 2010

Data are presented which detail the influence of several kinetical and structural factors on the polymerization of butadiene by rhodium chloride: the influence of catalyst concentration, the different activation energies, the requirements in emulsifier structure and concentration, and the striking influence of some diolefins were successively investigated; polymerization of butadiene and piperylene mixtures was also achieved. Indications concerning the type of this polymerization reaction are inferred from these results, and compared to the usually proposed coordination polymerization mechanisms.
A study of the polymerization of vinylic and diene compounds in the presence of amines
Authors: Margaritova M. F. , Stavrova S. D. , Trubitsyna S. N. , Medvedev S. S.
Published: June 2010

Investigation of the diene and vinylic compounds polymerization initiated by the four systems containing an amine have been carried out: I. benzoyl peroxide–dimethyl‐aniline: II. benzoic acid–dimethylaniline; III. ester–dimethylaniline; and IV. benzoyl peroxide–N‐cetylpyridinium chloride in alkaline condition. Systems II, III, and IV were not known before. Acrylonitrile and methyl acrylate are not polymerized in emulsion when systems II and IV are used. The scheme of interaction between benzoyl peroxide and dimethylaniline (system I) was proved by the spectral investigation. After the analogy of system I the mechanism of reaction for systems II and III was studied. It is proved experimentally that the initiating action of system IV is caused by the transformation of N‐cetylpyridinium chloride (in alkaline condition) into heterocyclic oxacompounds. These products have amine properties that interact with benzoyl peroxide according to the scheme mentioned for system I. On the basis of the proposed mechanism of polymerization initiation, the most probable explanation of the fact that acrylonitrile and methacrylate do not polymerize in emulsion with systems II and IV is given. The activation energy (E) and the predexponent (B) of the Arrhenius equation for methyl methacrylate polymerization are determined. The value of E for all the systems does not change in transition from mass to emulsion. B is by 2–4 orders more in emulsion than that in mass. The explanation of this fact may be given regarding the specific features of initiation with amines. The investigation of the poly(methyl methacrylate) microstructure showed that syndiotactic polymer is formed in the presence of system IV.
Studies in network formation
Authors: Bamford C. H. , Dyson R. W. , Eastmond G. C.
Published: June 2010

Networks are formed when free‐radical polymerization is initiated (thermally or photochemically) by a system consisting of a metal carbonyl or other zero‐valent metal derivative and a polyfunctional halide [e.g., poly(vinyl trichloracetate)] in a monomer for which termination is at least partly by combination. These reactions are suitable for investigations of the formation and also the preparation of networks. In ideal cases the ratio of combination to disproportionation in the termination reaction may be estimated. Some factors which may cause deviation from ideal behavior will also be discussed.
Energy gap and pre‐exponential factor in dark conduction by organic semiconductors
Authors: Eley D. D.
Published: June 2010

The values of Δε and σ0 in the expression σ = σ0 exp {−Δε/2kT} for the dark conductivity σ, tend to increase together over the whole range of organic semiconductors. They fall into a broad band of values confined roughly between two lines given by log σ0 = αΔε + β, the compensation rule, with log σ0 varying from 5 ± 4 for Δε equal to 1.0 e.v., to 14 ± 2 for Δε = 4.0 e.v. The parameter σ0 is related to the mobility of charge carriers μ, and the present paper attempts a broad qualitative discussion of the factors determining μ. The following mechanisms are considered to apply for the origin and motion of the charge carriers in order of increasing Δε and log σ0: (a) intrinsic bulk thermal generation, transport by hopping over intermolecular barriers, (b) bulk generation, with tunnelling through intermolecular barriers going over to, (c) narrow‐band theory, (d) electron or hole injection from the electrodes into the conductivity band for high energy gap substances. It is shown that process (b) can only account for a restricted range of log σ0, from 4 to 1.0, except perhaps for proteins where log σ0 = 4, may reflect a high mobility along the C0 … HN network. Electron injection may give rise to log σ0 = 1.6 and it seems possible that very much higher apparent values may arise from a temperature‐variable adsorbed film, on the semiconductor or the metal. Somewhat scanty evidence suggests that while atactic polymers may have low Δε values they may also have low values of log σ0. Going over to isotactic polymers may lower Δε somewhat, and increase σ0 by a factor of 10. It is suggested that to achieve high mobility values, e.g., μ = 104 cm.2 v.−1 sec.−1, it will be necessary to develop intermolecular bridging by metal atoms or hydrogen bonds, to assist charge‐carrier transport through the crystal.