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Two well-defined amphiphilic tetra-arm star block copolymers with a poly(ε-caprolactone) core and poly(ethylene glycol) arms were prepared by a hetero-complementary linkage reaction and studied with respect to their solution behavior in water.

We investigate the swelling of polymer model networks prepared at different polymer volume fractions and in solvents of different quality. We extend the existing theory to describe residual bond orientations (the vector and the tensor order parameters) for theta, good, and athermal solvents and put these relations in context with modulus at preparation conditions and the equilibrium degree of swelling. We find a good agreement with the assumption of affine swelling for the weakly entangled networks of our study. The same scaling relations (up to numerical coefficients) are obtained for the vector order parameter, m, and the tensor order parameter, S, as a function of the prepration conditions, network structure, the equilibrium degree of swelling, Q, and the modulus at swelling equilibrium, G. We obtain m\propto Q^{-2} and G\propto m^{3/2} for swelling in theta solvents and m\propto Q^{-1.08} with G\propto m^{2.14} in the good-solvent regime, in both cases independent of preparation conditions. Modulus and residual bond orientation are related by G\propto\phi_{0}m and G\propto\phi_{0}^{1.23}m as a function of the preparation polymer volume fraction \phi_{0} for theta solvents and good solvents, respectively. Computer simulations and experimental data for the good-solvent regime show good agreement with the predictions.

The preparation and investigation of gel films from a model amphiphilic polymer conetwork (ACN) grant a deeper control and understanding of the structure–property relationship in the bulk phase and at the interface of materials with promising applications. In order to allow the simultaneous transport of hydrophilic and hydrophobic substances, polymeric networks with finely distributed hydrophilic and hydrophobic components are very suitable. When designing new soft materials such as coatings, in addition to the structure in the bulk phase, the structure at the interface plays a critical role. In this study, two alternating tetra-arm star polymers poly(ε-caprolactone) (tetra-PCL-Ox) and amino-terminated poly(ethylene glycol) (tetra-PEG-NH2) form an amphiphilic polymer conetwork. The correlation between different synthesis strategies for gel films of this ACN model system and their resulting properties will be described. Through various spin coating techniques, control over film thickness and roughness is achievable and highlights differences to macroscopic gel samples. Atomic force microscopy (AFM) measurements reveal the effect of solvents of different polarities on the swelling ability and surface structure. This correlates with AFM investigations of the mechanical properties on ACN gel films, demonstrating a strong effect on the resulting elastic modulus E, depending on the presence or absence of a good solvent during synthesis. Furthermore, a higher E modulus is obtained in the presence of the selective solvent water, compared to the non-selective solvent toluene. This observation is explained through selective swelling of the tetra-arm star polymers displaying a different hydrophobicity.

The preparation and investigation of gel films from a model amphiphilic polymer conetwork (ACN) grant a deeper control and understanding of the structure-property relationship in the bulk phase and at the interface of materials with promising applications. In order to allow the simultaneous transport of hydrophilic and hydrophobic substances, polymeric networks with finely distributed hydrophilic and hydrophobic components are very suitable. When designing new soft materials such as coatings, in addition to the structure in the bulk phase, the structure at the interface plays a critical role. In this study, two alternating tetra-arm star polymers poly(ε-caprolactone) (tetra-PCL-Ox) and amino-terminated poly(ethylene glycol) (tetra-PEG-NH

A new approach for the synthesis of model amphiphilic polymer co-networks (ACN) based on a hetero-complementary reaction of an oxazinone terminated tetra-arm polycaprolactone star (tetra-PCL) with an amino-terminated tetra-arm polyethylene glycol star (tetra-PEG) is presented. The reaction conditions (solvent, concentration, temperature) were varied widely. Reaction kinetics and gelation were analyzed with high resolution NMR spectroscopy and computer simulations. The results agree with a nearly homogeneous mixture where local composition fluctuations affect kinetics only after most of the molecules are attached to the gel. Viscometry, dynamic light scattering data and literature data for the solubility parameters were combined to provide estimates for the Flory-Huggins interaction parameter of the two star polymers in toluene, chloroform, and THF as solvents. These estimates allow to collapse equilibrium swelling data in different solvents on a universal curve. Multiple quantum NMR analysis shows an enhanced formation of double connections between the same pair of stars as compared to preceding work on tetra-PEG gels made by the same cross-linking strategy but with a different coupling reaction. Besides of this last observation, the remaining results indicate that the networks possess a near model like structure with only a small fraction of pending arms as most relevant type of network defects.

Self-healing rubber mixtures are described, the cross-linking of which is based on both ionic cluster formation and supramolecular association. For this, brominated poly(isobutylene-co-isoprene) rubber (BIIR) was converted with modifiers which contained one uracil and one imidazole moiety. The reaction with the imidazole moiety resulted in the formation of ionic groups which associated to ionic clusters. Additionally, supramolecular association of the uracil groups with a bifunctional (bi-) linker containing two diamidopyridyl moieties contributed to physical cross-linking of the rubber via triple hydrogen bonding. Mechanical properties including self-healing of the rubber mixtures are discussed in terms of competing interactions and a softening effect caused by the bi-linker. The results are supported by DMA measurements and low-field multiple-quantum (MQ) NMR experiments which delivered information about the macroscopic properties and the underlying molecular dynamics, respectively. The reversible nature of the network formation and the softening effect of the bifunctional linker enable multiple reprocessing without sacrificing mechanical performance, which is an important feature that distinguishes the rubber mixtures significantly from covalently cross-linked rubbers.

Zusammenfassung Das Arbeitsfeld der neurophysiologischen Diagnostik hat sich in den vergangenen Jahren durch neue Untersuchungsmethoden um ein Vielfaches erweitert. Daraus resultiert eine Veranderung des Berufsbildes und dem erhohten Bedarf an qualifiziertem Personal. Das alleinige Anlernen in diesem spezifischen Arbeitsfeld wird den Qualitatsanforderungen an die Untersuchungen nicht gerecht und deckt schon jetzt nicht den vorhandenen Personalmangel. Neben einer grundstandigen Qualifizierung bedarf es lebenslangen Lernens in Form von professionellen Fort- und Weiterbildungen. Die Durchfuhrung der Untersuchungen nach einheitlichen Qualitatsstandards (SOPs) ist erforderlich und dient der Sicherung der Patientenversorgung.

Zusammenfassung Genau genommen sind es zwei besondere Falle. Erster Fall: Absencestatus folgend mit einem generalisierten tonisch-klonischen Anfall. Zweiter Fall: dissoziativer Anfall. Beide Anfallsformen werden gegenubergestellt um Unterschiede erkennen zu konnen. In der tonisch-klonischen Phase eines generalisierten Anfalles ist oft nur ein muskulares Artefaktogramm ableitbar. Auch wahrend eines psychogenen Anfalls uberwiegen oft die muskularen Artefakte. Eine Beobachtung des Patienten und eine genaue Dokumentation wahrend der Ableitung (am besten mit einer zusatzlichen Videoaufnahme) ist wegweisend fur eine plausible Befundung.

A co-polycondensation reaction is discussed analytically and by Monte-Carlo simulations where two reactive units compete for reactions with an alternating third reactive unit, whereby irreversible reactions replace bonds which are able to undergo exchange reactions. The resulting number average molar mass, $M_{\text{n}}$, exhibits only one distinct peak at the stoichiometric condition of both competitors with the alternating partner. The weight average molar mass, $M_{\text{w}}$, reaches an additional second peak at the stoichiometric condition between the dominating competitor and the alternating partner. Both peaks of $M_{\text{w}}$ surround a range of compositions where a rather high and approximately constant $M_{\text{w}}$ is obtained. The degree of polymerization of the dominating and alternating reaction partners is rather insensitive towards composition fluctuations if the reaction mixture remains within this composition window. This promotes high molecular weight species and more homogeneous weight distributions at incomplete mixing conditions. An ideal reference case (identical reaction rates for all reactions) is solved analytically to describe these reactions. The position of the stable composition window and the average molar masses inside this window can be tuned by choosing appropriate precursor molecules, reaction mixtures or post-tuning steps at later times.

Bisdithiooxalate has recently been introduced as a new thermo-reversible hetero Diels–Alder dilinker. Here, we demonstrate that the same compound has proved to be a very effective coupling agent for amino-terminated polyamides. Model reactions with aliphatic amines in solution show that bisdithiooxalate possesses four reactive centers which already react considerably fast at low temperatures (−10 °C). Under consideration of all assumed immediate and subsequent reactions, a kinetic model with four partial reactions is set up which allows to approximate the development of molar masses during chain extension of polyamide 12 theoretically. According to the model, high molar masses are achieved in a relatively wide range of mixing stoichiometry (ratio of coupling agent to amino-terminal groups). This is an essential advantage over conventional bifunctional coupling agents which require equivalency of the reacting groups to achieve high molar masses. In fact, coupling reactions of amino-terminated polyamide 12 in the melt show extraordinary increases in molar mass in a very short period of time over a wide concentration range. The key reactions of the coupling agent were identified by NMR spectroscopy. Deviations of the coupling behavior from the theoretical expectations are attributed to insufficient mixing of the components in the melt, which was not taken into account in the model.

Rubber composites were prepared by mixing bromobutyl rubber (BIIR) with silica particles in the presence of 1-butylimidazole. In addition to pristine (precipitated) silica, silanized particles with aliphatic or imidazolium functional groups, respectively, were used as filler. The silanization was carried out either separately or in situ during compounding. The silanized particles were characterized by TGA, 1H–29Si cross polarization (CP)/MAS NMR, and Zeta potential measurements. During compounding, the bromine groups of BIIR were converted with 1-butylimidazole to ionic imidazolium groups which formed a dynamic network by ionic association. Based on DMA temperature and strain sweep measurements as well as cyclic tensile tests and stress–strain measurements it could be concluded that interactions between the ionic groups and interactions with the functional groups of the silica particles strongly influence the mechanical and viscoelastic behavior of the composites. A particularly pronounced reinforcing effect was observed for the composite with pristine silica, which was attributed to acid–base interactions between the silanol and imidazolium groups. In composites with alkyl or imidazolium functionalized silica particles, the interactions between the filler and the rubber matrix form dynamic networks with pronounced self-healing behavior and excellent tensile strength values of up to 19 MPa. This new approach in utilizing filler–matrix interactions in the formation of dynamic networks opens up new avenues in designing new kinds of particle-reinforced self-healing elastomeric materials with high technological relevance.

The focus of this work is on the nature of self-healing of ionically modified rubbers obtained by reaction of brominated poly(isobutylene-co-isoprene) rubber (BIIR) with various alkylimidazoles such as 1-methylimidazole, 1-butylimidazole, 1-hexylimidazole, 1-nonylimidazole, and 1-(6-chlorohexyl)-1H-imidazole. Based on stress–strain and temperature dependent DMA measurements, a structural influence of the introduced ionic imidazolium moieties on the formation of ionic clusters and, as a consequence, on the mechanical strength and self-healing behavior of the samples could be evidenced. These results are fully supported by a molecular-level assessment of the network structure (cross-link and constraint density) and the dynamics of the ionic clusters using an advanced proton low-field NMR technique. The results show distinct correlations between the macroscopic behavior and molecular chain dynamics of the modified rubbers. In particular, it is shown that the optimization of material properties with regard to...

Zusammenfassung Die neurophysiologische Hirnstammdiagnostik hat durch den qualitativen Zuwachs in der bildgebenden Diagnostik an Wichtigkeit verloren. Dennoch kann die Bildgebung auch in der besten Auflosung keine funktionsspezifische Aussage machen (Ausnahme funktionelle Bildgebung). Im Vergleich: Ein Automotor kann in all seinen Einzelheiten bildgebend dargestellt werden, aber ob dieser Motor auch anspringt und ordnungsgemas lauft wird nur auf funktioneller Ebene geklart.

We present a detailed comparison of the microscopic dynamics and the macroscopic mechanical behavior of novel butyl rubber ionomers with tunable dynamics of sparse sticky imidazole-based sidegroups that form clusters of about 20 units separated by essentially unperturbed chains. This material platform shows promise for application as self-healing elastomers. Size and thermal stability of the ionic clusters were probed by small-angle X-ray scattering, and the chain and sticker dynamics were studied by a combination of broadband dielectric spectroscopy (BDS) and advanced NMR methods. The results are correlated with the rheological behavior characterized by dynamic-mechanical analysis (DMA). While the NMR-detected chain relaxation and DMA results agree quantitatively and confirm relevant aspects of the sticky-reptation picture on a microscopic level, we stress and explain that apparent master curves are of limited use for such a comparison. The cluster-related relaxation time detected by BDS is much shorter than the elastic chain relaxation time, although the weak conductivity does follow the latter. The systematic trends across the sample series suggest that all relaxations are dominated by a cluster-related activation barrier, but also that the BDS-based cluster relaxation does not seem to be directly associated with the effective sticker lifetime. Nonlinear stress-strain experiments demonstrate a reduction of sticker lifetime on stretching and that the stored stress and the elastic recovery depend on the deformation rate. �� 2019 American Chemical Society.

Poly(ionic liquid)s with alkyl imidazolium moieties in the main chain were synthesized by step growth addition polymerization of the AB monomers 1-(4-chlorobutyl)-1 H -imidazole, 1-(6-chlorohexyl)-1 H -imidazole, and 1-(6-bromohexyl)-1 H -imidazole in the melt. The molar masses of the polymers were controlled by adding 1-butyl-1 H -imidazole as monofunctional chain stopper. The bromine containing monomer polymerized spontaneously at room temperature whereas the chlorine containing monomers were sufficiently stable up to 40 °C. This could be evidenced by DSC measurements which showed a broad exothermal peak above 40 °C caused by the polymerization. MALDI-TOF investigations proved that dissociation of the alkyl imidazolium groups which might disturb the expected directional chain topology (AB-AB-AB…) did not occur. This is an important precondition for the intended cross-linking free grafting reactions of the AB monomers on halide containing polymers without any danger of gelation. Additionally, the results of the MALDI-TOF investigations indicated partial complexation of the polymer with the matrix and structural rearrangements during the measurements which converted the ionic imidazolium moieties into neutral moieties. The thermal behavior of the poly(ionic liquid)s has proved to be dependent on the length of the alkyl linking group between the imidazolium moieties and the type of counter ion.

Zusammenfassung Das Wissen uber das Ten-Twenty-System, den Elektrodenbezeichnungen, den technischen Parametern (Differenzverstarker-/Polaritatsprinzip) und der Identifizierung von Artefakten wird in diesem Artikel uberwiegend als vorausgesetzt angenommen. Der sog. „Herd“ oder „Fokus“ in einer EEG-Ableitung kann durch die sichere Anwendung von Verschaltungen bzw. Montagen im digitalen EEG relativ sicher identifiziert werden. Die genaue Beobachtung des Patienten und eine unterstutzende Dokumentation wahrend der EEG-Ableitung sind zwingend und vermeiden Fehlinterpretationen bei der Befundung.

New poly(ionic liquids) were synthesized by a two stage polymer analogous reaction. In the first stage, the reactive maleic anhydride groups of the starting polymer were converted with 1-(3-aminopropyl)-imidazole. The second stage comprises an alkylation reaction of the imidazole groups with various alkylbromides. This approach allowed tailoring of the polymer properties to a large extent. With the degree of conversion, the number of reactive groups remaining in the polymer could be adjusted. The possibility to preserve reactive groups opens new applications of the poly(ionic liquid)s as reactive blend components. As an example, reactive mixtures with bromobutyl rubber were prepared which exhibited pronounced self-healing properties.

Zusammenfassung Das Basiswissen zur Durchfuhrung einer EEG-Ableitung ist Voraussetzung fur eine selbststandige und selbstsichere Anwendung. Die daraus folgende artefaktarme EEG-Ableitung ist Grundlage fur eine qualitative Befunderhebung. Der routinierte Umgang mit Technik und Methoden bahnt eine souverane Patientenfuhrung.

Rubber composites were prepared by mixing bromobutyl rubber (BIIR) with silica particles in the presence of 1-butylimidazole. In addition to pristine (precipitated) silica, silanized particles with aliphatic or imidazolium functional groups, respectively, were used as filler. The silanization was carried out either separately or

In this work, we report about the mechanical relaxation characteristics of an intrinsically self-healable imidazole modified commercial rubber. This kind of self-healing rubber was prepared by melt mixing of 1-butyl imidazole with bromo-butyl rubber (bromine modified isoprene-isobutylene copolymer, BIIR). By this melt mixing process, the reactive allylic bromine of bromo-butyl rubber was converted into imidazole bromide salt. The resulting development of an ionic character to the polymer backbone leads to an ionic association of the groups which ultimately results to the formation of a network structure of the rubber chains. The modified BIIR thus behaves like a robust crosslinked rubber and shows unusual self-healing properties. The non-covalent reversible network has been studied in detail with respect to stress relaxation experiments, scanning electron microscopic and X-ray scattering. publishedVersion

Three new coupling agents with different numbers of N -acyl lactam and 4 H -3,1-benzoxazin-4-one groups were synthesized. A selective stepwise conversion of the coupling agents with 1-dodecanol and 1-dodecylamine was demonstrated by means of solvent-free model reactions in melt at 195 and 210 °C, respectively. These coupling agents are regarded as potential cores for the synthesis of novel star-like compounds and polymers with defined arms varying in type and lengths.

Hohe Verbandsgeldbußen statt Verfall Im Wirtschaftsstrafrecht, insbesondere im Bereich der Korruptions- und Wettbewerbsdelikte sowie der Vermögensermittlungen, werden zunehmend Ordnungswidrigkeitenverfahren zur Verhängung einer Verbandsgeldbuße (Unternehmensgeldbuße) geführt. Dieses Instrument wird als flexible Variante zum Recht des Verfalls in der Praxis immer wichtiger. Die Geldbußen liegen dabei oft im mindestens sechsstelligen Bereich. Lösungen für die Praxis Das Buch ist eine anwendungsorientierte Arbeitshilfe. Es ist bietet praktische Lösungen zu konkreten Problemen. Das Ineinandergreifen von materiellem Recht und Prozessrecht wird deutlich. Sowohl die Risiken als auch die Chancen der Unternehmensgeldbuße werden aufgezeigt. Voraussetzungen und Rechtsfolgen Einleitend geht der Autor zunächst auf Wesen und Begriff der Verbandsgeldbuße ein und zeigt ihre Ziele auf, bevor er sich ausführlich den Voraussetzungen und Rechtsfolgen der Verbandsgeldbuße widmet. Adressaten und Täter Klar beschreibt er die tauglichen Adressaten (juristische Personen, Personenvereinigungen, ausländische Verbände) sowie die Anknüpfungstat einschließlich ihrer Verfolgbarkeit. Bei der Darstellung der "Qualifikation" der Bezugstat erläutert der Verfasser die Verletzung verbandsbezogener Pflichten, die Bereicherung des Verbandes sowie die erstrebte Bereicherung. Die umfassenden Erläuterungen zu den tauglichen Tätern nach § 30 Abs. 1 OWiG behandeln z.B. • GmbH und GmbH & Co. KG, • Aktiengesellschaft, • Kommanditgesellschaft und Kommanditgesellschaft auf Aktien, • Genossenschaft, • Rechtsfähige Vereine, • Privatrechtliche Stiftung, • Juristische Personen des öffentlichen Rechts, • Societas Europaea und Europäische Wirtschaftliche Interessenvereinigung • Offene Handelsgesellschaft, • Gesellschaft bürgerlichen Rechts, • Partnerschaft sowie • Generalbevollmächtigte, Prokuristen und Handlungsbevollmächtigte.

A series of alternating polyester/polyamide block copolymers were prepared by sequential conversion of hydroxy-terminated polycaprolactone and amino-terminated polyamide-12 with a selectively reacting coupling agent. The thermal properties of the block copolymers were investigated using differential scanning calorimetry and dynamic mechanical analysis. Mechanical properties were determined using tensile and impact tests. All polymers were phase-separated, where the polyamide phase was semicrystalline in all compositions. Distinct crystallization of the polycaprolactone phase was observed only when the block length was greater than 2000 g mol−1. Mechanical testing showed that the polymers behave in a manner similar to that of thermoplastic elastomers. In particular, samples with a high content of polycaprolactone showed high strain and good impact behaviour. Copyright © 2011 Society of Chemical Industry

The formation of pseudopolyrotaxanes based on a polyelectrolyte, a surfactant and α-cyclodextrin (α- CD ) in aqueous solution is investigated. The polyelectrolyte and the surfactant form an ionic complex the side chains of which interact with each other. These interactions are strongly influenced by the formation of inclusion complexes with α- CD . It is shown by 1 H NMR and UV–vis spectroscopy that threading of the α- CD rings onto the side chains causes a shielding effect which increases the mobility of the side chains. The structure of the pseudopolyrotaxanes is concluded from ROESY spectra and their stoichiometry is determined by Job plots based on shift effects observed in the 1 H NMR spectra.

An attempt was made to explore the effects of interchange reactions on the crystallization, melting, and dynamic mechanical behavior of binary blends based on poly(trimethylene terephthalate) (PTT)/poly(ethylene 2,6-naphthalate) (PEN). 1 H NMR spectroscopy is used to verify the occurrence of interchange reactions at the interface, which are increased upon an increase in the melt processing time and temperature. The crystallinity of PTT was reduced while that of PEN was increased on blending. In addition, the crystallization temperatures of both phases showed depression. A single composition-dependent glass transition temperature (Tg) was detected in the second and subsequent heating thermo-grams of the blends, which is indicative of miscibility. The cold crystallization of the PTT phase was observed to increase while that of PEN was suppressed on blending. Each phase crystallized individually and a melting point depression was evident, which suggests a certain level of miscibility. Dynamic mechanical thermal analysis corroborated differential scanning calorimetry results. A constructive synergism was observed in the glassy state storage moduli of the blends, which is suggestive of a reduced specific volume of the system because of enhanced interactions and crystallinity.

Zur anteiligen Kompensation der Verformungen von Stahl- und Verbundtragern werden diese haufig uberhoht eingebaut. Wird die Uberhohung durch eine mechanische Beanspruchung (Boxen) aufgebracht, so besitzt der Stahltrager bereits im Einbauzustand plastische Dehnungen. Wie von Grages in [3] gezeigt, fuhrt dies bei der Ruckbelastung zu einer Abnahme der Steifigkeit. Dieses Phanomen ist auch als Bauschinger-Effekt [2] bekannt und kann bei praktischen Verformungsberechnungen zu einer Unterschatzung der tatsachlich auftretenden Deformationen fuhren. In dem aktuellen Aufsatz wird ein ratenunabhangiges elasto-plastisches Materialmodell mit linearer und nichtlinearer isotroper sowie nichtlinearer kinematischer Verfestigung vorgestellt, welches eine realistische Abschatzung der Verformungen erlaubt. Das gezeigte Materialmodell ist durch die geringe Anzahl an Eingangsparametern sehr einfach anwendbar. Eine gezielte Anpassung der einzelnen Parameter wird in anschaulicher Form dargestellt. Die Qualitat des Modells wird anhand der Nachrechnung von in [3] durchgefuhrten Versuchen uberpruft. An elasto-plastic material model for realistic calculation of the deformations of mechanical cambered steel- and composite girders. Steel and composite girders are often cambered before they are embedded into structures to compensate deflections. In case of a mechanical pre-deformation via a hydraulic press the steel girder contains plastic strains before assembly. As shown by Grages [3] this leads to a reduction of stiffness and strength during reverse loading. This phenomenon is also known as the Bauschinger-Effect [2] and may lead to an underestimation of the real deformation during a structural analysis. In this paper a rate-independent elastoplastic material model with linear and nonlinear isotropic as well as nonlinear kinematic hardening is introduced which allows a realistic estimation of deformations. The material model presented can be easily applied due to its low number of parameters. A straightforward algorithm to adjust the single parameters is described. The quality of the model is verified by a recalculation of experimental data from [3].

Wetlands at the riverside of the UNESCO Biosphere Reserve “Central Elbe” are highly contaminated by heavy metals, especially mercury (Hg). The Hg-polluted Elbe floodplain soils turn out to be a source of gaseous mercury via Hg volatilization from soil into the atmosphere. A modified field sampling method was used to measure total gaseous mercury (TGM) volatilization from three different sites at the Elbe River. The modified setup had a reduced chamber size and contained an internal gas circulation system. An in-ground stainless steel cylinder minimizes Hg volatilization from adjacent soil air. Cold vapor atomic absorption spectrometry (CV-AAS) was used to determine TGM amalgamated on gold traps. Sampled TGM amounts ranged between 0.02 and 0.63 ng (absolute), whereas the calculated Hg fluxes varied from 2.0 to 63.3 ng m−2 h−1. The modified system should allow measurements of Hg volatilization at various sites with a high spatial resolution, which should enable the study of interrelations between TGM emissi...

Thermal decomposition of binary blends composed of poly(trimethylene terephthalate) (PTT) and a phenoxy resin, namely poly(hydroxy ether) of bisphenol A, and prepared by melt blending was studied using thermogravimetric analysis. The thermal decomposition behavior of the blends could be explained in terms of formation and loss of hydrogen bonds and appearance of both low and high molecular weight species due to transesterification reaction between hydroxyl groups of phenoxy with ester bonds of PTT. The kinetics of decomposition reaction was analyzed by Freeman–Carroll, Friedman, Chang, and Vachuska–Voboril methods. It was found that all of the methods well described the decomposition reaction of the blends. The correlation between the calculated values and the chemical nature of the blends was acceptable. Among all the investigated methods the Chang method showed the best correlation with the experimental data. FTIR spectroscopy was employed to study the chemical structure of the blends. The results revealed strong interaction between the blend components in the form of hydrogen bonding. Progress of these interactions was followed with time and temperature. The effects of blending and loss of hydrogen bonding on degradation behavior in this kind of reactive blends were emphasized. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Three series of composite films based on polyimide and MWNTs were prepared by conversion of pyromellitic dianhydride and 4,4'-oxydianiline in the presence of the nanotubes, followed by thermal imidization. Carboxy- and amino-functionalized as well as unmodified nanotubes were used. It was demonstrated that just 0.5wt.-% of nanotubes increased the tensile properties of the composite films distinctly. Surprisingly, a significant influence of the functional groups on the mechanical performance of the composite films could not be demonstrated. However, it was shown that functional groups may reduce the conductivity of the films. Furthermore, the influence of ultrasonication is discussed.

A systematic approach was adopted to study multicomponent clay-containing nanocomposites using compatibilized and non-compatibilized blends of polyamide 6 (PA6)/acrylonitrile–butadiene–styrene terpolymer (ABS) and their organoclay (OMMT) nanocomposites. For this purpose PA6/styrene–acrylonitrile copolymer (SAN) based blends and nanocomposites were selected as simple model systems. In this way the role of each component of the systems, especially the clay, compatibilizer, and polybutadiene fraction on the formation of intercalated or exfoliated OMMT structures as well as resulting dynamic mechanical properties (DMA) could be elucidated. Structural analysis of the model systems using theoretical approach, and X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and DMA revealed that the most crucial factor in controlling the morphology and achieving different levels of dispersion is the extent of interaction between clay and the polymer matrix. Morphological analysis revealed that the OMMT layers were dispersed and exfoliated largely in the PA6 phase but, some were also accumulated at the rubber particle surface which remained non-intercalated. The effect of a compatibilizer on the dispersion of OMMT was not completely clear. The SAN based nanocomposites containing PA6 showed fully exfoliated OMMT structures, whereas the ABS based nanocomposites, having an additional rubber fraction, showed a mixed exfoliated and also partly non-intercalated morphology. The OMMT did not change the general occurrence of the co-continuous structures but refined the structures and led to mechanical stiffening as indicated by the DMA results. A correlation was established between the changes in the morphological states and the DMA properties.

The connection between the emission of atmospheric nitrogen (N) and the risk of groundwater pollution is significant for protection of the landscape with respect to the resources. The usually unknown amount of atmospheric nitrogen deposition has a high impact on N balances and on the leaching of nitrogen into the groundwater. Therefore, the present paper deals with the correlation between N emission and scenarios of potential risk assessment on N leaching into groundwater. The airborne N input into an agricultural landscape between the Saxon towns Taucha and Eilenburg (near Leipzig, Saxony) was measured by using the bulk N deposition method, the total atmospheric N deposition method with the ITNI system, and the bark sampling method, by focusing the results on the measurement of N input (punctual and regionalized) and on extrapolations to the risk of N leaching for planning purposes. On the forest measurement point the airborne N input is approximately twice as high as that on the ‘open land’ measurement ...

A carboxy terminated poly(butylene terephthalate) (PBT) was obtained by quantitative reaction of a hydroxy terminated PBT with succinic anhydride. Subsequent melt mixing with an amino group terminated PA12 did not result in the formation of linking groups between the components. Instead, the formation of succinimide terminal groups on the polyamide-12 (PA12) chains was observed. The same conversion in presence of a bifunctional coupling agent possessing one oxazoline and one oxazinone group yielded PA12/PBT block copolymers in high extent. DSC and microscopic measurements showed that a phase separated morphology is predominant.

Six soils used for rice (Oryza sativa L.) production were incubated using an automatic microcosm system. Production of trace gases (CO2, CH4, and N2O) and transformation of N, S, and metals (Fe and Mn) were studied in soil suspensions incubated from reducing to oxidizing conditions. Results show that soil pH variation was inversely correlated to soil redox potential (E-H) change (P 400 mV. Significant N2O production was observed between 200 and 500 mV Nitrification could also contribute to N2O production when E-H is > 500 mV, a possible critical E-H for the initiation of nitrification. The critical E-H for substantial immobilization of Fe and Mn was estimated to be around 50 and 250 mV, respectively. The intermediate E-H range (approximately -150 to 180 mV) provided optimum conditions for minimizing cumulative global warming potential resulting from CO2, CH4, and N2O production in soils. Our results have implications in interpreting the overall benefits of soil C sequestration efforts.

A chromophore terminated aliphatic polyether was obtained by polymer analogous conversion of the amino groups of Jeffamine® ED-600 with 4-[5-(4-acetoxy-phenyl)-3-oxo-penta-1,4-dienyl]benzoic acid and subsequent saponification of the acetoxy group. UV/Vis spectroscopic investigations showed that deprotonation of the chromophoric groups by organic or inorganic bases as for example poly(1,8-octamethyleneacetamidine) and NaOH, respectively, results in a distinct bathochromic shift of the chromophores longest wavelength absorption band by about 100 nm. This effect is discussed in terms of polymer blends where the covalently bound chromophore can act as optical probe for acid-base interactions between the components.

The kinetics of isothermal crystallization along with subsequent melting behavior of melt-mixed immiscible binary blends of poly(trimethylene terephthalate) (PTT) and polyamide-12 (PA12) were investigated by means of differential scanning calorimetry. Three macrokinetic models of Avrami, Tobin, and Malkin were used which could adequately describe isothermal crystallization kinetics of the blends as well as the neat components. However, the commonly used Avrami model provided more consistent data for the system of interest. Based on the half-time of crystallization, one could conclude that PTT crystallizes more rapidly than PA12. The kinetic parameters suggested that blending had a distinct influence on reducing the rate of isothermal crystallization particularly at medium degrees of undercooling. From reciprocal crystallization half-time, it was concluded that over the temperature range covered; the samples crystallized inside the nucleation-controlled region. The secondary nucleation mechanism generally prevailed in the PA12 isothermal crystallization whereas in PTT, the primary crystallization mechanism dominated. With respect to the position of melt transitions, blending was proven to exert only small effects, however, it reduced the crystallinity of both constituents particularly that of PA12 significantly. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Invented by Charles Goodyear, chemical cross-linking of rubbers by sulfur vulcanization is the only method by which modern automobile tires are manufactured. The formation of these cross-linked network structures leads to highly elastic properties, which substantially reduces the viscous properties of these materials. Here, we describe a simple approach to converting commercially available and widely used bromobutyl rubber (BIIR) into a highly elastic material with extraordinary self-healing properties without using conventional cross-linking or vulcanising agents. Transformation of the bromine functionalities of BIIR into ionic imidazolium bromide groups results in the formation of reversible ionic associates that exhibit physical cross-linking ability. The reversibility of the ionic association facilitates the healing processes by temperature- or stress-induced rearrangements, thereby enabling a fully cut sample to retain its original properties after application of the self-healing process. Other mechanical properties, such as the elastic modulus, tensile strength, ductility, and hysteresis loss, were found to be superior to those of conventionally sulfur-cured BIIR. This simple and easy approach to preparing a commercial rubber with self-healing properties offers unique development opportunities in the field of highly engineered materials, such as tires, for which safety, performance, and longer fatigue life are crucial factors.