bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology, microhardness, and flammability of compatibilized polyethylene/clay nanocomposites
Authors: Minkova L. , Peneva Y. , Valcheva M. , Filippi S. , Pracella M. , Anguillesi I. , Magagnini P. 
Published: March 2010

AbstractMorphology, thermal properties, and microhardness of ethylene‐glycidyl methacrylate copolymer (EGMA)/clay and ethylene‐acrylic ester‐glycidyl methacrylate terpolymer (EAGMA)/clay nanocomposites with different clay concentrations have been studied. The results have shown that EGMA and EAGMA are highly compatible with the organoclays Cloisite®20A (Cl20A) and Cloisite®30B (Cl30B). Intercalated structures are formed in the whole range of Cl20A loadings investigated, whereas partial degradation of the Cl30B organoclay was observed. The thermal characteristics and microhardness of EGMA/clay nanocomposites suggest that the filler dispersion deteriorates at high concentration. The concentrated EGMA/Cl20A nanocomposites have been used as masterbatches to prepare ternary high density polyethylene (HDPE)/Cl20A and low density polyethylene (LDPE)/Cl20A nanocomposites. Diffractometric characterization and scanning electron microscopy observations of these materials have shown that the intercalated structure of the starting EGMA/Cl20A masterbatches is preserved after dilution with the polyolefins. The results suggest that the silicate platelets remain localized within the EGMA droplets in the diluted nanocomposites. The latter display improved microhardness, whereas the mechanical properties, including elongation at break, are comparable with those of the neat polyolefins. Considerable enhancement of the flame retardant properties has been observed for the ternary nanocomposites. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Rheological and mechanical characteristics of low density polyethylene/ethylene‐vinyl acetate/organoclay nanocomposites
Authors: Behradfar Afsoon , Shojaei Akbar , Sheikh Nasrin 
Published: March 2010

AbstractAttempts were made to trace the effect of organoclay (OC) on the rheological and mechanical behaviors of the low density polyethylene (LDPE)/ethylene‐vinyl acetate (EVA) blends. To do this effectively, in addition to LDPE/EVA/OC system, pure LDPE and LDPE/EVA blends were also examined as model systems. The rheological behavior was determined by the capillary rheometer. Morphological characterization was also carried out using X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and theoretical approach based on interfacial energies. Shear viscosity, tensile strength and elastic modulus of LDPE/EVA were found to decrease by increasing the EVA content, while for LDPE/EVA/OC ternary nanocomposites, such properties showed an increase by increasing the content of EVA. Such behavior was explained by the morphological characteristic of the system in which OC was mainly intercalated/exfoliated in the EVA phase. This morphological characteristic was corroborated by the XRD, TEM and interfacial energies data. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Optical monitoring of the injection molding of intercalated polypropylene nanocomposites
Authors: Moretti Fernando , Favaro Márcia M. , Branciforti Márcia C. , Bretas Rosario E.S. 
Published: March 2010

AbstractIntercalated polypropylene (PP)/clay nanocomposites were produced by twin screw extrusion; afterwards, the optical monitoring of their injection molding was done using a laser sensor. The transmitted light intensity as a function of molding time was measured. The mold and melt temperatures, packing pressure and flow rate were changed. The nanocomposite had higher induction times than the PP, that is, scattering structures were detected later in the nanocomposite than in the PP, which was attributed to a retardation effect promoted by the clay on the PP crystallization growth rate. The morphologies of the injection molded samples were analyzed by polarized light optical microscopy, differential scanning calorimetry and transmission electron microscopy. The nanocomposite samples showed a second core, a thicker skin layer, highly oriented nanoclay's tactoids in the skin region and average spherulites' sizes smaller than the PP. The final light intensity If was correlated with the spherulites' sizes: high values of If represented samples with large spherulites. The PP sample had average spherulites' sizes larger than the Nano samples. However, the surging of a second core with large spherulites in the Nano samples changed the expected pattern: the PP samples showed If lower than the Nano samples. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Processing properties of polypropylene with a minor addition of silicone oil
Authors: Zhang Wei , Deodhar Sarang , Yao Donggang 
Published: March 2010

AbstractProcessing‐related properties of a polypropylene (PP)/silicone oil blend were investigated. It was found that an addition of a small amount (∼2 wt%) of silicone oil, a low molecular weight linear poly(dimethyl siloxane) (PDMS), drastically changed the rheological properties of PP. The PDMS seemed to work both as an internal lubricant and an external lubricant in the blend system. In particular, the apparent viscosity of the blend in capillary rheometry was approximately 10 times lower than that of virgin PP. The local minima in the viscosity versus shear rate curve in capillary rheometry and the gap‐dependency of viscosity in parallel‐plate rheometry implied the existence of a slip wall condition, caused by the formation of a thin lubricant layer at die walls. Thermal analyses and mechanical tests showed that the thermal and mechanical properties of the blend were nearly unaffected by the minor addition of silicone oil. The blend was tested in a profile extrusion process, and a significant reduction in die swell and profile distortion was achieved. The jet stretchability or spinnability in fiber spinning was also greatly improved with the minor addition of silicone oil. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Role of clay in compatibilization of immiscible high melt strength polypropylene and ethylene vinyl acetate copolymer blends
Authors: Bhattacharya Subhendu , Gupta Rahul K. , Bhattacharya Sati N. 
Published: March 2010

AbstractThe compatibilization efficiency of organically modified layered silicates (clay) was studied for immiscible high melt strength polypropylene/ethyl vinyl acetate (EVA) blends for the first time. The size of the dispersed EVA phase in the polypropylene matrix decreased with addition of small amounts of clay (cloisite 20A) to the blend. Scanning electron micrographs (SEM) show an efficient mixing of polymers in the presence of clay. The X‐ray diffraction (XRD) and transmission electron microscopy patterns demonstrate that silicate layers are well dispersed within the phases and are also present at the interphase. This results in substantial size reduction of the dispersed phase. The blends show a drastic increase in mechanical properties with the addition of clay. Differential scanning calorimetry thermo grams further help in understanding blend miscibility in the presence of clay as denoted by the change in the melting range of the components and the crystallization behavior of the components. The dynamic rheology tests reveal a emulsion‐like behavior for the blend system as denoted by the presence of a curvature or kink at lower frequencies, which further increases for the system with clay particles due to decrease in size of the dispersed phase. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Observation of instabilities in flow front during micro injection molding process
Authors: Kim Sun Kyoung , Choi Sung‐Ju , Lee Kwan‐Hee , Kim Dae‐Jin , Yoo Yeong‐Eun 
Published: March 2010

AbstractThis work has investigated filling characteristics during injection molding of a thin‐plate with microchannel patterns on it. To conduct molding experiments, an injection mold and mold inserts with microchannel patterns were designed and built. The experiments were conducted for three different channel sizes, and the results are analyzed. An unstable filling flow was observed in microscopic images for the smallest channel size. The front advanced with continuous creation and merge of microballs, which looked like teeth on the gum. We have analyzed this phenomenon and argued that there exists a critical channel width where such instability takes places. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Thermomechanical and barrier properties of UV‐cured epoxy/O‐montmorillonite nanocomposites
Authors: Peila Roberta , Malucelli Giulio , Lazzari Massimo , Priola Aldo 
Published: March 2010

AbstractMixtures of an epoxy resin and organophilic montmorillonites were subjected to ultraviolet (UV)‐induced photopolymerization. Two types of commercially available nanoclays, namely Cloisite 30B and Cloisite Na+, were modified through interaction with organic compatibilizers (dodecylsuccinic anhydride, octadecylamine, octadecyl alcohol, and octadecanoic acid). The modified nanoclays, dispersed in the liquid epoxy resin at 5 wt%, were photopolymerized to get nanocomposite films. The kinetics of the photopolymerization was evaluated by means of real‐time Fourier transform infrared spectroscopy. The modified nanoclays and their nanocomposites were characterized through X‐ray diffractometry; transmission electron microscopy showed the presence of intercalated and partially exfoliated morphologies in the nanocomposites. Thermogravimetric and dynamic‐mechanical analyses showed an increase of the thermal properties and an increase of the glass transition temperatures of the nanocomposites compared with that of the neat UV‐cured resin. Finally, the oxygen barrier properties of nanocomposite films, coated on a polyethyleneterephtalate substrate, were evaluated; the decrease of permeability was correlated with the degree of exfoliation of the nanocomposites. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Residual stresses in the quasi‐simultaneous laser transmission welding of amorphous thermoplastics
Authors: Bonefeld Dirk , Schöppner Volker , Potente Helmut , Mahnken Rolf , Shaban Ahmed 
Published: March 2010

AbstractLaser transmission welding is frequently being used increasingly for joining complex, assembly‐oriented components, thanks to its small heat affected zone. As a result of the cooling processes, residual stresses can develop inside the components, potentially leading to stress cracking and premature component failure. One subgoal of process design should therefore be to reduce the level of residual stresses as far as possible when laser welding is employed. This work looks into experimental testing for residual stresses, as a factor for the weld parameters in quasi‐simultaneous laser transmission welding, with the objective of determining the optimum welding parameters. The ARAMIS optical measuring system for deformation analysis was used to this end, in conjunction with a modified hole‐drilling method. POLYM. ENG. SCI., 50:1520–1526, 2010. © 2010 Society of Plastics Engineers
Effect of glycerol on structure–property relations in chitosan/poly(ethylene oxide) blended films investigated using wide‐angle X‐ray diffraction
Authors: Jagadish Rampura S , Raj Baldev , Parameswara Puttanna , Somashekar Rudrappa 
Published: March 2010

AbstractPolymer blending is an effective method for providing desirable polymeric materials with properties useful for the packaging industry. In the study reported, blends of chitosan/poly(ethylene oxide) (PEO) were prepared in various weight ratios with and without glycerol. Line profile analysis of the X‐ray diffraction patterns of these blended films was carried out. Microstructural parameters such as crystallite size and lattice strain were determined using paracrystalline modelling of X‐ray data. These values were correlated with physico‐mechanical and optical properties of the chitosan/PEO blends with and without glycerol to understand the holistic behaviour of the blends. Two prominent Bragg reflections at 2θ ≈ 19° and 23° were observed in the wide‐angle X‐ray diffraction patterns of the glycerol‐based chitosan/PEO blended films of various ratios. Interruption of PEO crystallization with chitosan results in an amorphous polymer network and hence a reduction in crystallite size by almost 97.7%. For glycerol‐based blends, the crystallite size/area decreases to 94.4% of the virgin crystallite size. The X‐ray profile analysis supports the results for the physico‐mechanical properties of the blends. The results show that the addition of 20 wt% of glycerol results in an increase of the elongation at break by more than 150%, meaning that these chitosan/PEO films could be applied in flexible packaging. Copyright © 2010 Society of Chemical Industry
The Role of Acidification for Antimicrobial Activity of Atmospheric Pressure Plasma in Liquids
Authors: Oehmigen K. , Hähnel M. , Brandenburg R. , Wilke Ch. , Weltmann K.‐D. , von Woedtke Th. 
Published: March 2010

AbstractWater disinfection by indirect plasma treatment was investigated using a surface dielectric barrier discharge (DBD). Liquid was neither part of the discharge electrode configuration nor stirred during plasma treatment. High concentrations (106–108 cfu·mL−1) of Escherichia coli and Staphylococcus aureus have been completely inactivated within 5–15 min, depending on liquid sample volume. Inactivation occurred in non‐buffered liquids, only, where pH decrease was found. Measurements of pH, nitrate, and nitrite concentrations after DBD plasma or NO gas treatment lead to the conclusion that nitric acid formation from plasma‐generated reactive nitrogen species are the main source of liquid acidification. Incubation of bacteria in nitric acid alone did not result in comparable inactivation effects. Increase of H2O2 concentration was found as a result of plasma treatment of liquids but not after treatment by NO gas. Therefore, synergistic action of both reactive oxygen and nitrogen species are discussed to be responsible for antimicrobial plasma effects.magnified image
pH‐sensitive properties of barium strontium titanate (BST) thin films prepared by pulsed laser deposition technique
Authors: Buniatyan Vahe V. , Abouzar Maryam H. , Martirosyan Norayr W. , Schubert Jürgen , Gevorgian Spartak , Schöning Michael J. , Poghossian Arshak 
Published: March 2010

AbstractpH‐sensitive properties of barium strontium titanate (BST) high‐k thin films as alternative gate material for field‐effect capacitive (bio‐)chemical sensors based on an electrolyte‐insulator‐semiconductor system have been investigated. The BST films of different compositions (Ba0.31Sr0.69TiO3, Ba0.25Sr0.75TiO3and Mg‐doped Ba0.8Sr0.2Mg0.1Ti0.9O3) were deposited by pulsed laser deposition technique from targets fabricated by self‐propagating high‐temperature synthesis. The realised sensors have been electrochemically characterised by means of impedance‐spectroscopy, capacitance–voltage and constant‐capacitance method. The sensors possess a Nernstian‐like pH sensitivity in the concentration range between pH 3 and 11 with a response time of 5–10 s. An equivalent circuit model for the BST‐based capacitive field‐effect sensor is discussed.
Softlithographic partial integration of surface‐active nanoparticles in a PDMS matrix for microfluidic biodevices
Authors: Demming Stefanie , Hahn Anne , Edlich Astrid , Franco‐Lara Ezequiel , Krull Rainer , Barcikowski Stephan , Büttgenbach Stephanus 
Published: March 2010

AbstractThe mergence of microfluidics and nanocomposite materials and their in situ structuring leads to a higher integration level within microsystems technology. Nanoparticles (Cu and Ag) produced via laser radiation were suspended in Poly(dimethylsiloxane) to permanently modify surface material. A microstructuring process was implemented which allows the incorporation of these nanomaterials globally or partially at defined locations within a microbioreactor (MBR) for the determination of their antiseptic and toxic effects on the growth of biomass. magnified image
Partially structured PDMS with nanoparticle–PDMS composite.
Surface chemistry and topographical changes of an electropolished NiTi shape memory alloy
Authors: Neelakantan Lakshman , Valtiner Markus , Eggeler Gunther , Hassel Achim Walter 
Published: March 2010

AbstractElectropolishing and its mechanism for NiTi shape memory alloy in methanolic sulfuric acid have been investigated recently. In the current study, X‐ray photoelectron spectroscopy was carried out to characterize the chemical nature of the electropolished surface. The electropolished surface is covered by a thin layer of TiO2. For an electropolished specimen, the Ni:Ti ratio at surface (∼1 nm) was 0.31, whereas for a mechanically polished specimen the ratio was 0.70. The second aspect of this work is the attempt to characterize the salt film formed during electropolishing. The characterization of salt‐film showed sulfide and sulfate compounds of Ni and/or Ti. The crystallographic and topographical changes caused due to thermally induced phase transformation on an electropolished NiTi was followed by in situ XRD and AFM. AFM studies revealed significant changes in the surface features due to phase transformation. The surface roughness value increased by a factor of 2.
In situ cross‐linking of the shell of self‐assembled peptide nanotubes
Authors: Gokhale Rhishikesh , Couet Julien , Biesalski Markus 
Published: March 2010

AbstractPeptide polymer nanotubes (PPNTs) were prepared by in situ surface‐initiated atom transfer radical polymerization (ATRP) from self‐assembled cyclic peptide nanotubes. PPNT dimensions, i.e., height (i.e. diameter) and length, as derived from AFM measurements of surface‐adsorbed, dry PPNT are a function of the molar mass of the peptide‐attached polymer molecules, and the overall structure is determined by subtle interplay of peptide–peptide and polymer–polymer interactions. As shown in previous communications, a PPNT length reduction occurs with increasing grafted mass of polymer chains. The latter may be attributed to strong segment–segment interactions of the nanotube‐grafted macromolecules. Here, we introduce a possible strategy to chemically stabilize PPNT. Peptide‐polymer nanotubes are prepared by in situ cross‐linking of the polymeric shell using the bi‐functional monomer ethylene glycol dimethacrylate (EGDMA) during surface‐initiated polymerization. PEGDMA‐PPNTs were characterized with respect to chemical identity, chemical stability and structure in the dry state, using FTIR, dissolution assays, and atomic force microscope (AFM) cross‐section analysis, respectively. The use of the cross‐linkable monomer yields chemically stable rigid‐rod like hybrid materials, where the overall length of the nano‐objects remains at a constant value of about 100 nm regardless of the adsorbed mass of the nanotube‐surrounding polymer material.
Capacitive electrolyte–insulator–semiconductor structures functionalised with a polyelectrolyte/enzyme multilayer: New strategy for enhanced field‐effect biosensing
Authors: Abouzar Maryam H. , Poghossian Arshak. , Siqueira José R. , Oliveira Osvaldo N. , Moritz Werner , Schöning Michael J. 
Published: March 2010

AbstractA novel strategy for enhanced field‐effect biosensing using capacitive electrolyte–insulator–semiconductor (EIS) structures functionalised with pH‐responsive weak polyelectrolyte/enzyme or dendrimer/enzyme multilayers is presented. The feasibility of the proposed approach is exemplarily demonstrated by realising a penicillin biosensor based on a capacitive p‐Si–SiO2 EIS structure functionalised with a poly(allylamine hydrochloride) (PAH)/penicillinase and a poly(amidoamine) dendrimer/penicillinase multilayer. The developed sensors response to changes in both the local pH value near the gate surface and the charge of macromolecules induced via enzymatic reaction, resulting in a higher sensitivity. For comparison, an EIS penicillin biosensor with adsorptively immobilised penicillinase has been also studied. The highest penicillin sensitivity of 100 mV/dec has been observed for the EIS sensor functionalised with the PAH/penicillinase multilayer. The lower and upper detection limit was around 20 µM and 10 mM, respectively. In addition, an incorporation of enzymes in a multilayer prepared by layer‐by‐layer technique provides a larger amount of immobilised enzymes per sensor area, reduces enzyme leaching effects and thus, enhances the biosensor lifetime (the loss of penicillin sensitivity after 2 months was 10–12%).
Molecular rectification in metal–bridge molecule–metal junctions
Authors: Liu Yaqing , Offenhäusser Andreas , Mayer Dirk 
Published: March 2010

AbstractMolecular bridged nanocontacts allow direct electrical addressing of electroactive molecules, which is of interest for the development of molecular based electronic devices. In the present paper, the electroactive molecule 6‐ferrocenyl‐1‐hexanethiol (Fc‐HT) was integrated into metal–bridge–metal (MBM) junctions assembled in a scanning tunneling microscope (STM) setup. A diode‐like behavior was observed from the current/bias (It/Vb) signal through Au (substrate)/Fc‐HT/Au (tip) junction, which presented an asymmetric current response due to the resonant tunneling between metal electrode and ferrocenylthiol molecules. With gate electrode modulation, the enhancement of the tunneling current can be controlled, which allows to tune the direction of the current rectification. Our investigations demonstrated that ferrocenylthiol bridged MBM nanostructure has potential applications in the future design of higher‐order heterojunctions components in combination with electrochemical logic gates.
Comprehensive plasma‐screening for known and unknown substances in doping controls
Authors: Thomas Andreas , Guddat Sven , Kohler Maxie , Krug Oliver , Schänzer Wilhelm , Petrou Michael , Thevis Mario 
Published: March 2010

AbstractOccasionally, doping analysis has been recognized as a competitive challenge between cheating sportsmen and the analytical capabilities of testing laboratories. Both have made immense progress during the last decades, but obviously the athletes have the questionable benefit of frequently being able to switch to new, unknown and untested compounds to enhance their performance. Thus, as analytical counteraction and for effective drug testing, a complementary approach to classical targeted methods is required in order to implement a comprehensive screening procedure for known and unknown xenobiotics. The present study provides a new analytical strategy to circumvent the targeted character of classical doping controls without losing the required sensitivity and specificity. Using 50 µL of plasma only, the method potentially identifies illicit drugs in low ng/mL concentrations. Plasma provides the biological fluid with the circulating, unmodified xenobiotics; thus the identification of unknown compounds is facilitated. After a simple protein precipitation, liquid chromatographic separation and subsequent detection by means of high resolution/high accuracy orbitrap mass spectrometry, the procedure enables the determination of numerous compounds from different classes prohibited by the World Anti‐Doping Agency (WADA). A new hyphenated mass spectrometry technology was employed without precursor ion selection for higher collision energy dissociation (HCD) fragmentation experiments. Thus the mass spectra contained all the desired information to identify unknown substances retrospectively. The method was validated for 32 selected model compounds for qualitative purposes considering the parameters specificity, selectivity, limit of detection (<0.1–10 ng/mL), precision (9–28%), robustness, linearity, ion suppression and recovery (80–112%). In addition to the identification of unknown compounds, the plasma samples were simultaneously screened for known prohibited targets. Copyright © 2010 John Wiley & Sons, Ltd.