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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

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.

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.

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.

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

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.

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

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

Interactions of phenolic and carboxylic groups containing NLO chromophores with NaOH in methanol were investigated by UV/vis, fluorescence and 1 H NMR measurements. With the aid of a mathematical fitting procedure, it was possible to separate the single contributions of the differently charged chromophore molecules to the overall UV/vis spectra. Individual concentrations of the involved species in dependence on the NaOH concentration were calculated by approximation of measured and calculated UV/vis spectra. The fully deprotonated chromophores with their higher extent of conjugation did not exhibit remarkable fluorescence while the 3rd order NLO activity was observed to show the opposite behavior.

Segmented block copolymers were synthesized in melt by conversion of carboxy-terminated poly(propylene oxide) and amino-terminated PA12 with a selectively reacting bifunctional coupling agent bearing one oxazoline and one oxazinone group. The reaction was performed either in one or two steps. In the latter, it could be shown that the sequence of mixing significantly influenced the course of reaction. The structure of the linking group formed during the reaction was verified by 'H NMR spectroscopy using model compounds. DSC and TEM investigations evidenced that the block copolymers are phase separated. Domains in a size of several nanometers are found. Owing to the two phase structure, the block copolymers show ductile behavior with the tendency to elastomeric behavior. Tensile properties of the block copolymers increase with the content of PA12. Elongations at break were measured with values up to 500%.

Unsaturated aromatic polyesters were obtained by glycolysis of poly(trimethylene terephthalate) with cis-2-buten-1,4-diol followed by a solid-state polymerization. The glycolysis was performed in a batch mode as well as through a continuous process in a twin screw extruder. The degradation and subsequent rebuilding of the polymer chain during the course of reaction was followed by means of inherent and melt viscosity measurements, and 1H NMR terminal group analysis of the intermediates and the final products. Structural investigations revealed that this new approach resulted in melt processible unsaturated polyesters with cross-linkable sites having similar characteristics to that of the virgin saturated polyester. Although the processing temperature for the different reaction steps was sufficiently high (180−260 °C), no thermally induced cross-linking of the incorporated unsaturated bonds could be evidenced indicating that the obtained products remained stable during the production stage. For comparison purposes, a commercial unsaturated polyester (Vestodur©) was included in the investigations. UV irradiation of thin polyester films did not result in cross-linked products but in cis–trans isomerization of the incorporated bisoxybutenyl unit.

The purpose of this study was to measure the effects of plant growth on soil microbial biomass C (C mic ) and soil enzyme activities. In a pot experiment using spring barley and sugar beet, we investigated the response of C mic , hot water extractable C and N fractions (C hwe , N hwe ), and enzyme activities involved in C, N and P cycling in a loess-derived Chernozem from Bad Lauchstadt (Central Germany). The study site has been receiving the same fertilisation treatments for 100 years. The soil originated from plots fertilised with 15 t ha −1 farmyard manure (FYM) year −1 + mineral fertiliser (NPK), or 15 t ha −1 FYM year −1 , or NPK or from an unfertilised control. Pots were sampled monthly, and alkaline phosphatase- (AP), β-glucosidase- and protease-activities were analysed. At the beginning and the end of study, levels of C mic , C hwe and N hwe were also measured. All three enzyme activities and C mic were significantly and positively correlated with C org and C hwe . Results suggest that the enzyme activities measured originated mostly from microorganisms and that C hwe is an important C source for soil microorganisms. β-Glucosidase and AP activities were higher in summer months than at other times. In contrast, protease activity changed only slightly during the growing period.

Blends of poly(trimethylene terephthalate)/bisphenol A polycarbonate (PTT/PC) with different compositions were prepared by melt blending. The effect of transesterification on the miscibility and phase behavior of the blends was studied using DSC, DMA, and 1 H NMR. The DMA results revealed a two-phase system with partial miscibility. DSC thermograms of the first heating scan showed a crystallizable system in which addition of PC-phase reduces the degree of crystallinity. However, the cooling and also the second heating scans revealed the complete miscibility of all the blends. It was concluded that annealing at 300 °C (to remove thermal history of the blends) caused the constituents to undergo the transesterification reaction, which changes the blend to a miscible system. The miscibility is due to formation of block copolymers with different block lengths which also suppress the crystallization of the system. The degree of randomness and sequence lengths of the copolymers were determined to analyze the extent of transesterification reaction and structure of the system. It was observed that as the reaction progresses, the degree of randomness increases and the sequence length of the copolymers decreases. Moreover, both increase of reaction time and temperature increased the extent of reaction. The results of DSC and 1 H NMR showed that a small amount of reaction is needed to change this system to a miscible blend.

Blends of poly(trimethylene terephthalate) (PTT) and polycarbonate (PC) over full composition range were prepared using a twin-screw extruder. A glycidyl methacrylate-based terpolymer was used to modify the interface of the blends. Morphological examinations were carried out using transmission electron microscopy (TEM) and confirmed the biphasic structure of the blends. Dynamic rheological response of the blends was recorded in the linear viscoelastic region. It was observed that addition of the terpolymer to the system increases the dynamic shear moduli and complex viscosity of the blends, which is attributed to interactions of the terpolymer at the interface of two phases leading to a restricted chain mobility of the blend components. The Veenstra model was found to be able to describe dynamic shear modulus of the PTT/PC 50/50 blend; however, for the compatibilized blend of PTT/PC 50/50, the fit is not as good as that of uncompatibilized system, which is believed to be due to formation of micelles in this system.

An understanding of agroecosystems is the key to estimate the influence of agricultural production methods on the environment, including soil, water and air quality. The present study aimed to contribute to the insufficient knowledge of functional and structural soil microbial properties influenced by organic and inorganic fertilisation and climatic conditions at two European long-term field experiments. Soil microbial biomass, activities of alkaline phosphatases, β-glucosidases and proteases, and phospholipid fatty acid profiles were evaluated in soils from three different fertiliser treatments (inorganic, NPK; farmyard manure, FYM; without, CON) at two sites (Bad Lauchstadt, Germany and Keszthely, Hungary). The results showed that Corg and Nt concentrations were significantly higher in the FYM plots compared to the NPK amendments or CON. Furthermore, increases were observed in the Cmic and the enzyme activities of FYM-fertilised treatments in the soil at Bad Lauchstadt. NPK fertilisation significantly decreased Cmic in the soil at Keszthely, whereas FYM increased the activity of β-glucosidases. Ecophysiological parameters (Cmic-to-Corg and qCO2) revealed a clear climatic influence on edaphic properties. The profiles of 28 phospholipid fatty acids (PLFAs) were used to assess whether observed changes in functional microbial parameters were accompanied by changes in the composition of the microbial communities after FYM and NPK amendments. The results of principal component analyses indicate that the communities of the autochthonous microflora differed between the two sites and three treatments. Bacteria, particularly Gram-negative bacteria and eukaryotes were responsible for these differences. The results support the hypothesis that fertilisation in general and its forms (organic versus inorganic) affect important functional and structural soil microbial properties. PLFA analysis proved to be a more sensitive indicator than functional parameters.

In order to determine the total input of reactive nitrogen from the atmosphere into the soil–plant system, a method was developed on the basis of 15 N isotope dilution called Integrated Total Nitrogen Input (ITNI). This is the only method known which measures directly the active uptake of nitrogen by aboveground plant parts. It is applied at the pot scale. As in all pot experiments, extrapolating the findings to a large area is problematic. Moreover, the method's advantage–quantification of the uptake of nitrogen by aboveground plant parts—also entails a disadvantage in that vegetation type has a pronounced effect on the total deposition of nitrogen. This influence exerted by the plant is examined and discussed using both published and new findings. Based on this critical analysis, proposals are derived for improving the process of extrapolating the measurements from the pot to field scale. These proposals are verified using existing measurements.

Morphology and rheology of poly(trimethylene terephthalate)/metallocene linear low-density polyethylene (PTT/m-LLDPE) immiscible blends with varying extent of compatibilization were experimentally examined and theoretically analyzed using Palierne and Coran models. A glycidyl methacrylate-based terpolymer was used to modify the interface of the blend. The particle radius in the PTT75/m-LLDPE25 system decreases in proportion to the level of added compatibilizer up to 5 wt% of terpolymer, beyond which the particle size remains unchanged. This is attributed to the saturation of interface by interfacial modifier leading to diminish the effectiveness of the compatibilizer. Morphological observations reveal that the saturation of the interface for PTT25/m-LLDPE75 system occurs at 2.5 wt% compatibilizer content. Rheological examinations show a sharp reduction of complex viscosity for the latter system at 10 wt% terpolymer which is ascribed to the micelle formation in the bulk phase. Plots of the relaxation time spectrum exhibit that upon addition of the compatibilizer the magnitude of the relaxation peaks associated with interface increases which is ascribed to the increase of the interfacial area. The Palierne model fails to predict admissible values and reasonable trend for interfacial tension. This failure is believed to be due to the excessively large difference between the complex shear modulus values of the dispersed and matrix phases. However, the Coran model used to describe the dynamic moduli, shows a good fit to the experimental data.

Binary melt blends of two thermoplastics—poly(trimethylene terephthalate) (PTT) and polyamide-12 (PA12)—having a large difference in zero-shear viscosity values, were prepared in different blending ratios (PTT/PA12 90/10, 75/25, 25/75, 10/90) by means of a twin-screw extruder. Scanning electron microscopy (SEM) confirmed droplet morphology subsequently quantified using image analysis. Dynamic rheological behavior at blending temperature (230°C) was also recorded on a parallel plate oscillatory rheometer within the linear viscoelastic range. The applicability of two emulsion models, the Palierne analysis plus the Gramespacher and Meissner model, as well as a micromechanical model, the Coran analysis, to describe the dynamic moduli of the system in different compositions was investigated and also a comparison on these models was presented. POLYM. ENG. SCI., 45:1401–1407, 2005. © 2005 Society of Plastics Engineers

New bifunctional coupling agents possessing one 2-oxazoline group and one 2-oxazinone group were converted in a Haake melt mixer or extruder with PA6 and PA12. It was shown by means of NMR spectroscopic investigations that the 2-oxazoline group reacted mainly with carboxylic groups whereas the oxazinone group reacted preferably with the amino groups. Both reactions proceeded with high selectivity and independent from each other. In the case of carboxy/amino group terminated polyamides, the conversions resulted in increased molecular weights since both reactive terminal groups of the polyamides were addressed simultaneously by the coupling agent. In the case of amino group terminated polyamides, the conversion with the bifunctional coupling agent resulted in oxazoline terminated polymer chains. Unlike PA6, it was possible to convert PA12 in two steps. At lower temperatures (210°C) and short reaction times (2 min), the reaction of the oxazinone group with the amino groups was predominant, whereas the reaction of the oxazoline group with the carboxylic groups proceeded to a sufficient extent only after longer reaction times or at higher temperatures. In the case of PA6, processing temperatures of about 250°C were necessary. Here, a side reaction was observed that resulted in the formation of cyclic quinoxaline structures under evolution of water. This side reaction did not disturb the chain extension significantly. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2170–2177, 2004

Hydrolytic degradation of an aliphatic polyacetamidine at different pH values was studied using 1 H NMR spectroscopy. It could be shown that degradation occurred at neutral and basic conditions whereas under acidic conditions the polyamidine was stable. In the course of degradation, aliphatic acetamide, amine and acetic acid are formed. The ability of the polyamidine to release active compounds bonded ionically to the polymer backbone by hydrolytic decomposition was studied by UV spectroscopy. The measurements were performed on a mixture of the polyamidine and salicylic acid as an example. The release behavior of a 1:0.8 mixture at pH 7 was nearly linear within the first 10 h and went to completion after 30 h. This system is discussed with respect to the development of new drug delivery systems based on polyamidines.

Varying atmospheric nitrogen (N) depositions for different crops were observed at Bad Lauchstadt (Saxony-Anhalt, Germany) when using the ITNI system (ITNI = Integrated Total Nitrogen Input), which is based on the 15N isotope dilution method. These differences were only partly explained by climatic influences. The effects of crops on the atmospheric N deposition measured by the ITNI system are discussed. For this purpose, data of six different plant species recorded in 1998 were re-analyzed. It was found that the airborne N input is closely correlated with the morphology and metabolism of crops. Daily atmospheric N depositions of 129.0–360.8 g per hectare were measured for the plant species used. The nutritional supply of plants, especially with N, is another factor of influence on the N input from the atmosphere which should be considered. To investigate this aspect, a pot experiment was conducted with the grass Lolium perenne at three different N levels. An increase in the airborne N uptake (corresponding to N fertilization) was observed as biomass production rose. Einfluss von Nutzpflanzenarten und deren Wachstum auf die atmospharische Stickstoffdeposition Im Rahmen von atmogenen Stickstoffdepositionsmessungen am Standort Bad Lauchstadt (Sachsen-Anhalt, Deutschland) mittels des auf der 15N-Verdunnungsmethode beruhenden ITNI-Systems (ITNI = Integrated Total Nitrogen Input), konnte festgestellt werden, dass es in Abhangigkeit von der Nutzpflanzenart zu verschiedenen N-Depositionen kommt. Diese Unterschiede liesen sich nur teilweise durch klimatische Einflusse erklaren. Im Beitrag wird die Wirkung der Pflanzenart auf den atmospharischen N-Eintrag diskutiert. Dazu wurden Datensatze des Jahres 1998, in dem sechs Nutzpflanzenarten getestet wurden, herangezogen. Es zeigte sich, dass die atmogene N-Deposition sehr stark von der Pflanzenart bzw. deren Stoffwechsel und morphologischen Merkmalen abhangig ist. Fur die untersuchten Nutzpflanzen konnten tagliche atmospharische N-Eintrage in der Grosenordnung von 129 bis 360,8 g pro Hektar festgestellt werden. Da diesbezuglich auch die Nahrstoffversorgung von Pflanzen insbesondere mit N eine Rolle spielt, wurde ein Gefasexperiment angelegt, in dem der Einfluss des Grases Lolium perenne auf den atmogenen N-Input bei drei N-Dungungsstufen untersucht wurde. Mit steigender Biomassebildung, entsprechend der N-Dungung, kam es zu einer Zunahme des atmogenen N-Eintrages.

FT-IR spectroscopy was used to study the specific interactions in an aliphatic polyacetamidine and its mixtures with a dicarboxylic acid. In the pure polyacetamidine, hydrogen bonds between the amidine groups were observed. After heating, considerable changes in the position of the interacting group vibration bands were found. These changes were reversible on cooling. In mixtures with glutaric acid strong acid base interactions resulting in the formation of ionic polymer networks were observed. These networks have proven stable up to at least 150 °C.

A new convenient method for the synthesis of substituted 2,6-diacetamido pyridines has been developed. It starts from 4-hydroxypyridine and comprises the introduction of the amino groups by the Chichibabin reaction. After several protection and deprotection steps 2,6-diacetamido-4-hydroxy pyridine is obtained, which is regarded as a key compound for the synthesis of various substituted 2,6-diacetamido pyridines. It is shown that the free hydroxy group is susceptible for nucleophilic substitution. This provides an easy access to the introduction of different functional groups at 4-position of 2,6-diacetamido pyridine. The advantages over other procedures described in the literature are discussed.

The non-covalent interactions between 2-oxazoline containing phenols and an aliphatic polyamidines as well as an inorganic base were studied. The reaction of a weak acid with a strong base results in the formation of the deprotonated species and subsequently in the formation of a new electronic structure. A bathochromic shift of the wavelength of the absorption maxima of the chromophores bounded to polyamidine was observed. Depending on the structure of the chromophore, the shift of the absorption maxima is 40-100 nm. The changes in photochemical behavior can be explained by the higher portion of quinoid structures in the conjugated π-system. The degree of deprotonation is dependent on the molar ratio of the chromophore and the polymeric base. Analogous results were obtained with an inorganic base.

A series of aliphatic polyacetamidines (1) with the common structure [-CH 2 ) m -N=C(CH 3 )-NH-] n was synthesized by the phenol-catalyzed melt polycondensation reaction of various aliphatic diamines with triethyl ortho acetate. The resulting polyacetamidines were characterized by 1 H and 13 C NMR spectroscopy. It could be shown that the NMR spectra are strongly influenced by the solvents used. In pyridine and CD 3 OD, prototropic tautomerism of the amidine group was observed. In pyridine this process is mainly caused by intermolecular proton exchange between two amidine groups whereas in CD 3 OD, proton exchange mainly proceeds via the solvent. The methyl residue on the amidine group revealed pronounced CH-acidity, which is apparent in a proton-deuteron exchange when CD 3 OD was used as a solvent. In CF 3 COOD, the respective amidinium salts were formed. It was found the thermal stability of the polymers increased with increasing chain length of the aliphatic diamines. The shorter aliphatic diamines formed cyclic products with a defined structure.

For a long time, measurements of the electrokinetic potential have been used in colloid chemistry mainly for the calculation of electrostatic interaction forces in colloid systems. Moreover, electrokinetic measurements are increasingly successful in characterising solid surfaces. Studies of the effects of pH, surface-active agents, etc. on the electrokinetic potential give valuable information about the nature of solid surfaces. According to Jacobasch [Prog. Org. Coat. 17 (1989) 115], it is possible to distinguish between dissociation and adsorption processes. We are also able to recognise chemical reactions on the surface during measurement. Electrokinetic properties of different polyformamidines should give us an idea about the chances of this method. While electrokinetic properties of colloidal particles have been widely investigated by means of electrophoresis, the electrokinetic characterisation of the surface of macroscopic specimens is still rather uncommon. Indeed, the use of a commercial electrokinetic analyser (EKA) streaming potential measurement apparatus (Anton Paar KG, Graz, Austria) allows the rapid and reproducible measurement of streaming potential, including those of plates and sheets. By means of these investigations, we are able to tackle problems of adhesion of coatings on polymers. This was already demonstrated at the influence of different finishing methods like oxygen plasma treatment or flame treatment on the surface of polypropylene rubber blends [Prog. Org. Coat. 26 (1995) 131; J. Adhes. Sci. Technol. 9 (1995) 327]. By creating special conditions, we succeeded in measuring streaming potentials on metal surfaces, as shown by the example of Al-sheets. With the help of these measurements, different surface treatments were determined.

Two azobenzene containing 2-oxazolines were used for labeling of a polyester with carboxylic end groups by the end-capping method. The modification was performed under the conditions of either reactive processing or in a solution. Photochemical activity of the prepared polymers, as well as that of the modifiers was studied. The polymers prepared represent new photosensitive materials that undergo photochemical trans-cis isomerizations and reverse cis-trans reactions.

Two azobenzene containing 2-oxazolines were used for labelling of polyesters with carboxylic end groups by the end-capping method. The reaction proceeded under the conditions of reactive processing, and in a solution. High conversions in melt were achieved in several minutes. The coupling of the modifiers was proved by NMR spectroscopy.