bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the association phenomena of poly(methyl methacrylate) in nonpolar theta solvents
Authors: Suzuki Hidematsu , Hiyoshi Tatsuo , Inagaki Hiroshi 
Published: June 2010

AbstractOn a sample of poly(methyl methacrylate) prepared by an anionic polymerization technique with sodium biphenyl in tetrahydrofuran at –78°C, abnormal cloud‐point curves in nonpolar theta solvents, p‐xylene, and carbon tetrachloride were observed. The effect of solvent polarity on precipitation behavior of the sample solutions was examined. It is found that the more polar the solvent used, the more normal the cloud‐point curve becomes. Osmometry on the sample solutions in p‐xylene yielded much higher molecular weights than those obtained in a good solvent (toluene) and in a polar theta solvent (acetonitrile). The results obtained show that poly(methyl methacrylate) molecules prepared in this manner are liable to associate with each other in nonpolar media. This feature is considered to be responsible for the observed anomalies in the cloud‐point curves. This type of association is discussed and compared with the other two kinds of association phenomena reported in the literature.
Polymer solutions: A law of corresponding states for the coexistence curves
Authors: Daoud M. 
Published: June 2010

AbstractWe recall the main results of two different theories for temperature (T) and monomer concentration (C) dependence of flexible polymer solutions, namely, the Edwards–Flory–Huggins theory and the critical theory where an analogy with critical phenomena is used. These results are then compared to experimental data obtained by small‐angle neutron scattering associated to chain labeling by deuteration. Our new results are summarized in a (T, C) diagram and by a set of characteristic power laws. We also propose a law of corresponding states for the coexistence curves.
One long chain among shorter chains
Authors: de Gennes P. G. 
Published: June 2010

AbstractWe discuss the end to end distance RN of one long chain, with N monomers, immersed in a solution of shorter chains, each with P monomers, in a good solvent. When P increases, RN crosses over an excluded volume behavior (RN ∼ N3/5) to an ideal behavior (RN → R1n ∼ N1/2). The relevant crossover parameter Z is constructed here from an improved version of the Edwards screening idea, incorporating the correct scaling laws. The result is

where ϕp is the volume fraction of the P chains in the solution. The N chain will be ideal when Z ⪖ > 1, and swollen (non‐Gaussian) when Z ⪖ > 1.
Configurational behavior of adsorbed polymer molecules
Authors: Lal M. , Stepto R. F. T. 
Published: June 2010

AbstractMonte Carlo calculations of the configurational behavior of adsorbed polymer molecules are described. Freely rotating lattice chains of 30, 50, 75, and 100 bonds adsorbing from athermal solutions at different adsorption energies have been studied. The adsorption energy is defined as Δϵs, the energy change on breaking a segment–solvent bond and forming a segment–surface bond. Adsorption occurs only for negative values of Δϵs. Results of calculations at Δϵs = −0.9kT and −0.5kT have been analyzed numerically and compared with previous data.Several ways of characterizing the configurational behavior are presented in terms of fraction of segments adsorbed, thickness of adsorbed layer, “train,” “loop,” and “tail,” lengths, and (r2) and (s2) of the adsorbed chain. At Δϵs = −0.9kT the chains are strongly adsorbed with extended configurations and short tails. At Δϵs = −0.5kT the chains are only just adsorbing with the thickness of the adsorbed layer dominated by the lengths of the tails.Finally, a visuographic technique for presenting the ciné display of the configurational behavior of the adsorbate chains is described briefly.
Structure and morphology of liquid‐crystalline polymers
Authors: Wendorff J. H. , Finkelmann H. , Ringsdorf H. 
Published: June 2010

AbstractLiquid‐crystalline phases are characterized by structures intermediate between a three‐dimensionally ordered crystal and a disordered fluid. Polymers with liquid‐crystalline structures can be obtained from specific monomers containing mesogenic groups with a tendency to form liquid‐crystalline phases. These mesogenic groups are either incorporated into the main chain or attached to a chain as side groups. In both cases liquid‐crystalline structures, and also enantiotropic liquid‐crystalline phases, have been reported. Smectic polymers are characterized by layered structures with long‐range order in the direction of the layer normal and two‐dimensional short‐range order within the layers. The nematic polymers are characterized by a preferred direction on a microscopic scale and short‐range positional order of the centers of mass of the mesogenic groups. Thermal and textural properties are similar to the corresponding properties of low molecular weight liquid crystals.
Preparation and characterization of head‐to‐head polymers. VIII. Head‐to‐head poly(vinyl cyclohexane)
Authors: Helbig M. , Inoue H. , Vogl O. 
Published: June 2010

AbstractHead‐to‐head poly(vinyl cyclohexane) (H‐H PVCH) was prepared from 2,3‐diphenylbutadiene, which was polymerized by radical, 1,4 polymerization to poly(2,3‐diphenylbutadiene) and then catalytically hydrogenated to H‐H PVCH, H‐H PVCH was also prepared by catalytic hydrogenation of H‐H polystyrene (PS). The catalytic hydrogenations were carried out at an initial hydrogen pressure of 2000 psi and a temperature of 200°C. Some chemical, physical, and thermal properties of H‐H PVCH were investigated and compared with the properties of atactic and isotactic head‐to‐tail (H‐T) PVCH. The glass transition temperature of the H‐H polymer was found to be 50°C lower than that of the atactic H‐T polymer which indicates that the backbone chain has more flexibility. Both H‐H and H‐T PVCH showed comparable thermal stability. The temperature of the maximum rate of thermal degradation by differential thermogravimetric analysis was approximately 40°C higher than that of the corresponding polystyrenes.
Isomeric copolymers of acetylenes
Authors: Simionescu C. , Dumitrescu Sv. , Percec V. 
Published: June 2010

AbstractThe triple bond opening in the cis position during Ziegler polymerization of acetylenes does not result however in pure cis polymers. The heat of polymerization and the exothermal effect of catalyst destroying has been found to be responsible for the variable cis content due to cis‐trans thermal isomerization. The cis‐trans thermal isomerization is accompanied by cyclization and scission of the polymer chains. These side reactions lead to copolymer structures instead of homopolymer ones. These processes probably determine the low thermal stability of the polymers (even at room temperature), and at the same time allow the interpretation of the order‐disorder phenomenon found by Ehrlich in the case of high crystalline polyphenylacetylene at about 120°C.
Properties and reactivity of polysuccinimide
Authors: Vlasák J. , Rypáček F. , Drobník J. , Saudek V. 
Published: June 2010

AbstractA simple method has been suggested for the fractionation of polysuccinimide (PSI); the intrinsic viscosities of fractions were measured and the parameters of the Mark‐Houwink equation were determined. The possibilities of reactions of PSI with primary amines such as histamine, tyramine, tryptamine, mono‐BOC‐ethylenediamine, glycine nitroanilide, and ethanolamine were checked; the reaction rate constants and the effect of some catalysts were determined.
Radical coordination polymerization
Authors: Kabanov V. A. 
Published: June 2010

AbstractIn this paper different examples of the effect of coordination‐unsaturated metal compounds on the radical homo‐ and copolymerization of vinyl monomers are considered and analyzed. In all known cases homopolymerization proceeds according to the usual addition chain radical scheme and involve an initiation step with the formation of a primary radical. Complexed radicals or monomers take part in the chain propagation steps. In the case of copolymerization, a complexing agent can considerably influence apparent relative activities of monomers, decreasing or increasing the tendency to alternation. If two monomers are present in the system, one of which forms a complex with a Lewis acid, and the other is a donor with respect to this complex, the formation of a ternary donor‐acceptor complex also occurs in a number of cases. A ternary complex can fulfill the monomer function in the chain propagation reaction, i.e., it can add to the propagating chain as an independent kinetic species. In such cases, strictly alternating copolymers may be obtained. All mechanisms considered agree with the addition‐polymerization scheme. From the kinetic point of view the ternary complex addition is somewhat similar to an elementary step of Butler's inter‐intramolecular cyclopolymerization.
DSC studies on the activated anionic polymerization of ϵ‐caprolactam in the presence of crown compounds
Authors: Karger‐Kocsis József , Kiss László 
Published: June 2010

AbstractActivated anionic polymerization of ϵ‐caprolactam was investigated in the presence and absence of crown compounds by a suitable differential scanning calorimetry (DSC) technique. It was demonstrated that crown compounds influenced the heterogeneous character of polymerizationresulting PA 6 of higher crystalline proportion and higher average molecular weight.
Structure–property relationships in main chain liquid crystal polyesters with flexible spacers
Authors: Lenz Robert W. 
Published: June 2010

AbstractInvestigations have been carried out in this laboratory over the past four years on the structure—property relationship in main chain, thermotropic liquid crystal polymers containing a variety of different types of mesogenic groups and flexible spacers. Our goal has been to relate the effect of polymer structure to the type of mesophase formed in the melt and to the melting and clearing temperatures of the mesophases. Many interesting, unusual, and unexpected results have been obtained in our survey, and this review is concerned with our observations on the molecular factors which determine the types of mesophases formed, nematic or smectic, and their transition temperatures and behaviors.
The polymerization of xylylene bisdialkyl sulfonium salts
Authors: Wessling R. A. 
Published: June 2010

AbstractParaxylylene bisdialkyl sulfonium salts can be polymerized in several different ways, yielding addition polymers as well as condensation polymers. The chemistry leads to a variety of polymers including poly(p‐xylylene), poly(p‐xylylidene), poly(xylylene sulfide)s, poly(xylylene oxide)s, and various α‐substituted polyxylylenes such as poly(p‐xylylene‐α‐dialkylsulfonium chloride). Addition polymers form via xylylene diradical intermediates. Condensation polymerization can be effected either by coupling with aldehydes or by nucleophilic displacement reactions.
Multicomponent gas sorption in glassy polymers
Authors: Koros W. J. , Sanders E. S. 
Published: June 2010

AbstractGlassy polymers are nonequilibrium solids whose properties may change slowly due to time‐dependent variation in the excess volume and enthalpy functions of these materials. Measurable changes in the gas sorption behavior of samples exposed to different time–temperature histories below the polymer's glass transition temperature can be explained primarily in terms of differences between the excess volume of different samples. A simple physical and mathematical model will be described which relates excess sorption in glasses, compared to rubbery polymers, to sorption into excess volume frozen into the quenched matrix. The model will be explained for pure component gases and then generalized to treat multicomponent sorption data for the CO2/C2H4 and CO2/N2O systems in poly(methyl methacrylate). The rather complex mixed gas behavior can be predicted quantitatively using only pure component sorption data in conjunction with the generalized model for multicomponent gases. The model, based on the concept of competition of sorbing penetrants for the excess volume present in the glass, is successful for the two systems described above for total pressures up to 300 psia.
Homogeneous nucleation temperatures for concentrated polystyrene/benzene solutions
Authors: Prud'Homme Robert K. , Gregory Walter J. , Andres Ronald P. 
Published: June 2010

AbstractHomogeneous nucleation temperatures for polystyrene/benzene solutions up to 60 wt% polymer have been measured. For polymer molecular weights from 17,500 to 100,000, homogeneous nucleation temperatures increase with increasing concentration from 226°C for pure benzene to 260°C for 60 wt% polymer. The experimental results have been compared to the predictions of homogeneous nucleation theory. It is concluded that for these solutions polymers affect the nucleation process principally through their effect on surface tension and solvent vapor pressure. For polystyrene solutions of molecular weight 600,000 or greater, a significant reduction in nucleation temperature was found. This phenomena appears to be caused by phase‐separated domains in these high molecular weight solutions.
Cvclization of polystyrene chains in the crossover region between theta and good solvents: Cyclization dynamics of polymers 12
Authors: Winnik Mitchell A. , Li Xiao‐Bai , Guillet J. E. 
Published: June 2010

AbstractThe rate constants and the equilibrium constants for end‐to‐end cyclization have been determined in seven solvents for a polystyrene chain of Mn ‐ 2900 and narrow molecular weight distribution. These values were obtained by measuring the kinetics of intramolecular excimer formation between pyrene groups attached to the chain ends. Values were plotted versus the Hildebrand solubility parameter h: It was found that not only did the rate of cyclization decrease in good solvents, but that the rate of ring opening was substantially faster in good solvents than in poor solvents. Consequently, the cyclization equilibrium constant is far more sensitive to the quality of the solvent than is the mean‐squared radius of gyration. The results are interpreted in terms of excluding volume effects on the end‐to‐end distance distribution function of the polymer.
Direct Evidence of Covalent Immobilisation of Microperoxidase‐11 on Plasma Polymer Surfaces
Authors: Yin Yongbai , Bilek Marcela M. M. , McKenzie David R. 
Published: June 2010

AbstractThe question of whether immobilised proteins are bound covalently on plasma activated or deposited polymers has been a challenge for almost 30 years, as there has been no directly evidence to conclude unambiguously. In this paper, we report evidence that a chemical binding reaction occurred during immobilisation of microperoxidase‐11 (MP‐11) proteins on plasma polymer surfaces. Untreated polymer surfaces were not resistant to detergent cleaning and did not show any increase of S 2p component after protein immobilisation, whilst all plasma‐deposited surfaces showed large amounts of immobilised MP‐11 proteins after detergent cleaning. We conclude that the MP‐11 protein had a chemical binding reaction thorough its cysteine residues with the plasma polymer surfaces.magnified image
Tragverhalten und EN 1993‐1‐konforme Nachweisformate für Rahmenecken mit geschraubter Zuglasche
Authors: Rubert Achim , Schäfer Steffen 
Published: June 2010

AbstractFür im Sinne der EN 1993‐1‐8 als biegesteif/starr zu bewertende Rahmenecken mit geschraubter Zuglasche wird mittels eines einfachen Stabwerkmodells unter Berücksichtigung der Grenztragfähigkeiten der Komponenten (plastische Berechnung) das Tragverhalten des Riegels im Bereich der Laschenverschraubung analysiert. Daraus werden zum Handnachweis geeignete Formeln zur Berechnung der Beanspruchungen und geeignete Nachweisformate der Tragfähigkeit nach EN 1993‐1‐1 und 1993‐1‐8 einschließlich eines Abschätzungsnachweises mit Extremwerten vorgestellt. Mögliche Sonderregelungen der nationalen Anhänge von EN 1993‐1‐1 und 1993‐1‐8 bleiben hier ohne Berücksichtigung. Unter Beachtung des statischen Satzes der Traglasttheorie werden damit sichere und gleichzeitig wirtschaftliche untere Grenzen der Tragfähigkeit der riegelseitigen Rahmenecke mit geschraubter Zuglasche dargestellt.Am Beispiel einer ausgeführten Hallenkonstruktion zeigt sich, dass für den Bereich der Zuglaschenverschraubung mit diesen Nachweiskonzepten eine häufig geforderte und kostenerhöhende Zugflanschverstärkung unnötig ist.Structural performance and EN 1993‐1 compliant design formats for frame corners with a bolted tension splice. For frame knees considered as fixed/stiff according to EN 1993‐1‐8, the structural performance of the rafter bolted to a tension slice is analyzed by means of a simple frame model with respect to maximum loadcarrying capacities of components (plastic calculation). Refering to this, formulas of calculations to determine the internal forces and the proofs of carrying capacity of the components due to EN 1993‐1‐1 and 1993‐1‐8 including a proof with extreme values are shown. Possible special regulations of national appendices of EN 1993‐1‐1 and 1993‐1‐8 remain here without consideration. With regard to the guarantied lower limit of the plastic collapse load several safe and economic calculation formats for the bolted side of a frame knee are shown.The example of a built hall construction shows that – following the proposed design formats – frequently demanded/arranged and additionally costs raising tension flange reinforcements are unnecessary.
Berechnung des Abhebens von verankerten Flüssigkeitsbehältern unter Erdbebeneinwirkung
Authors: Habenberger Jörg 
Published: June 2010

AbstractDie horizontalen Einwirkungen aus Erdbeben können bei Flüssigkeitsbehältern zum Abheben des Bodenblechs führen. Damit verbunden sind zusätzliche Axialkräfte in der gegenüberliegenden Behälterwand und Verformungen des Bodenblechs. Insbesondere die Verdrehungen des Bodenblechs sind oftmals kritisch für den Nachweis der Erdbebensicherheit. Verankerungen können das Abheben wirkungsvoll begrenzen, wobei z. B. Ringfundamente oder Mikropfähle die in den Ankerbolzen auftretenden Zugkräfte aufnehmen. Im vorliegenden Beitrag wird die Wirkung der Verankerung am Gesamtsystem von Behälterwand und Bodenblech untersucht. Dieses wird mit ebenen FE‐Schalenelementen unter Berücksichtigung nichtlinearen Materialverhaltens für die Ankerbolzen modelliert. Der dynamische Druck des verankerten Behälters aus horizontaler Erdbebenanregung wird inkrementell als statische Last aufgebracht und mit dem statischen und dynamischen Flüssigkeitsdruck aus vertikaler Erdbebenanregung überlagert. In jedem Lastschritt wird iterativ das Abheben des Tankbodens berechnet. Die Ergebnisse werden den Angaben des EC 8, Teil 4, Anhang A gegenübergestellt.Uplift analyses of anchored liquid storage tanks under earthquake excitation. Horizontal earthquake excitations may lead to an uplift of the base plate of liquid storage tanks. The uplift results in additional axial forces on the opposite site of the tank wall and rotational deformations in the base plate. Especially the rotation of the tank base plate is critical for the verification of the earthquake resistance. Anchorages can effectively restrict the uplift while ring foundation or piles bear the appearing tensile forces. In the present paper the effect of anchorages is analysed on the overall system of tank wall and base plate. The tank shell is modelled by flat shell elements. The anchor bolts are considered as spring elements with nonlinear material behaviour. The dynamic pressure of the anchored tank due to horizontal excitation is applied incrementally to the tank shell. The uplift and the material nonlinearity are considered by iterative calculations at every load step. The results are compared with the specifications of EC 8, part 4, appendix A.
The Importance of Process in Building an Executive Leadership Team: A Case Study
Authors: Zakariasen Kenneth L. 
Published: June 2010

In today's competitive, fast-changing world of healthcare, organizations cannot tolerate ineffective leadership over the long term if they are to remain successful. It is very common for leadership teams to come together and immediately begin to do business…at least to attempt to do what each team member believes the group's business should be. Unfortunately, each person probably has a different idea of what the team's business should be, and how they should go about conducting it. This is a certain recipe for ineffectiveness. The following case study examines how the executive team in a health sciences college approached the development of an effective leadership team, and discusses the importance of process to achieving the desired outcomes. The process so described can be used with any leadership team, but it should always be customized to suit the unique needs and desires of each team.
Health Policy and the Delivery of Evidence-Based Wound Care Using Regional Wound Teams
Authors: Campbell Karen , Teague Laura , Hurd Theresa , King John 
Published: June 2010

As clinicians practicing wound management in all three sectors of the healthcare system, the authors have articulated specific issues relating to wound management. There is a lack of awareness of the extent of the problem. Best practice guidelines have been developed, however, their adoption and transfer into practice have been inconsistent. Basic education in the field is minimal or absent across all disciplines. Institutions and agencies lack the infrastructure and financial resources to support optimal healthcare delivery in wound prevention and management. As a result, there are significant problems and inconsistencies in access to wound care across Ontario. This paper reviews the issues and background as related to pressure ulcer, diabetic foot ulcer and venous leg ulcer. Finally, the authors make specific health policy recommendations regarding the implementation of regional wound care teams.
BREAKING THE SILENCE
Authors: Gueye Abdoulaye 
Published: June 2010

AbstractSince the turn of the millennium, French society has become the theatre of a noticeable Black agency. Few previous events have ignited the media's interest in a Black French agenda more than the Collectif Égalité-led “March for the dignity of Black peoples” and the formation of the Conseil Représentatif des Associations Noires (CRAN). Through these newly-founded organizations, French activists of African descent have been challenging the hegemonic ideology of color-blindness, and heralding the claims, problems, and expectations of postcolonial African-descended people.Informed by this ideology of so-called color-blindness, the academic literature in France has been slow to account for this new form of political expression. Moreover, as this article will argue, postcolonial African-descended people have not been recognized as political agents in the French literature. Few studies have attempted to correct this myopic view by analyzing the current political dynamic of postcolonial African-descended people. Due to the state-centered or institutionalist approach, these studies are more concerned with highlighting external and structural factors, such as racial discrimination, at the expense of endogenous determinants. They focus on what postcolonial African-descended people are denied in the French society instead of investigating the qualities these citizens actually possess that enable them to organize collectively. This article is intended to contribute to this new literature. It will pinpoint the different transformations that postcolonial African-descended people have undergone from the 1960s through the 1990s, examine the resources and skills under these actors' control, and gauge the contribution of these resources and skills to the emergence of a Black collective voice.