Jürgen Pionteck

Leibniz Institute of Polymer Research Dresden, Dresden, Saxony, Germany

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Publications (166)404.97 Total impact

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    ABSTRACT: Living Reference Work Continuously updated edition
    No preview · Book · Jan 2016
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    Saheli Roy · Suneel Kumar Srivastava · Jürgen Pionteck · Vikas Mittal
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    ABSTRACT: An efficient approach has been applied to assemble MgAl-layered double hydroxide (LDH) onto the pristine CNTs (PCNT) using sodium dodecyl sulfate (SDS) molecule. The assembling process and formation of such hybrid nanostructure were established by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM). Subsequently, the hybrid was used as nanofiller in development of high performance TPU/NBR (1:1 w/w) blend nanocomposites. Measurements of mechanical and dynamic mechanical properties show that tensile strength, elongation at break and storage modulus improved significantly by 171%, 1.8 times and 241 % in 0.50 wt% loading of hybrid filler in blend. TGA showed that thermal stability of 0.50 wt% hybrid filled blend compared to neat is maximum improved by 20 °C determind at 50 % weight loss. DSC showed the maximum enhancement in melting temperature (7 °C) and crystallization temperature (31 °C) due to significant nucleation efficiency of the filler, homogeneous dispersion, and strong interfacial interaction between polymer matrix and filler.
    Full-text · Article · Oct 2015 · Polymer International
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    J. S. Sefadi · A. S. Luyt · J. Pionteck · U. Gohs
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    ABSTRACT: The effects of surfactant and electron beam (EB) radiation treatment on the morphology and properties of polypropylene (PP)/expanded graphite (EG) composites were investigated. Surfactant treatment and sonication of EG before mixing with PP significantly influenced the morphologies of the composites, and the modification of EG with sodium dodecyl sulphate (SDS) had a strong negative influence on the electrical conductivities of these composites. The electrical percolation concentration is shifted from 5 to 6 wt% filler to about 10 wt% filler in the presence of SDS. The melting and crystallization temperatures of PP in the composites were not affected by surfactant or EB radiation treatment. There were small differences in PP crystallinity, depending on the type and combination of treatments. The filler particles acted as nucleating agents and the crystallization temperatures shifted to higher temperatures. The thermal stability of PP was significantly higher after irradiation, and improved even further for the samples containing EG, but the presence of EG had little influence on the thermal stabilities of the non-irradiated composites. For both non-irradiated and irradiated composites the maximum tensile stress and elongation at break values are lower than the neat matrix, while the tensile modulus increased significantly.
    Full-text · Article · Sep 2015 · Journal of Materials Science
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    ABSTRACT: Electrical conductivity of the supercooled ionic liquid [C8MIM][NTf2], determined as the function of the temperature and pressure, highlights strong differences in its ionic transport behavior between low and high temperature regions. To date, the crossover effect which is very well-known for low molecular van der Waals liquids is rarely described for classical ionic liquids. This finding highlights that the thermal fluctuations could be a dominant mechanism driving the dramatic slowing down of ion motions near Tg. An alternative way to analyze separately low and high temperature dc-conductivity data using a density scaling approach was then proposed. Based on which a common value of the scaling exponent γ=2.4 was obtained, indicating that the applied density scaling is insensitive to the crossover effect. By comparing scaling exponent γ reported herein along with literature data for other ionic liquids, it appears that γ decreases by increasing the alkyl chain length on the 1-alkyl-3-methylimidazolium-based ionic liquids. This observation may be related to changes in the interaction between ions in solution driven by an increasing of the van der Waals type interaction by increasing the alkyl chain length on the cation. This effect may be related to changes on the ionic liquid nanostructural organization with the alkyl chain length on the cation as previously reported in the literature based on molecular dynamic simulations. In other words, the calculated scaling exponent γ may be then used as a key parameter to probe the interaction and/or self-organizational changes in solution with the respect to the ionic liquid structure.
    No preview · Article · Jul 2015 · Soft Matter
  • Haisong Qi · Jianwen Liu · Jürgen Pionteck · Petra Pötschke · Edith Mäder
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    ABSTRACT: Electrically conductive aerogels composed of carbon nanotubes (CNTs) and cellulose were used as vapour sensors for the first time. The vapour sensing behaviours of these aerogels were investigated by monitoring the electrical resistance change upon exposure to a series of volatile organic compound (VOC) vapours such as methanol, ethanol, toluene, and others. The effects of vapour types, CNT contents and vapour concentrations on relative electrical resistance change were analyzed. The results revealed that CNT–cellulose composite aerogels exhibit rapid response, high sensitivity and good reproducibility to both polar and nonpolar vapours. The dominant mechanism for these aerogels as vapour sensors is the resistance change from chemical molecule absorption by both CNT networks and cellulose matrix. This is mainly due to the unique three-dimensional (3D) porous structure of materials, which also broadens the scope of analytes to be detected. This work provides a novel concept for developing a new class of chemical sensors by combining the nature of CNTs with the 3D porous matrix.
    No preview · Article · Jul 2015 · Sensors and Actuators B Chemical
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    ABSTRACT: Pressure-Volume-Temperature (PVT) measurements and broadband dielectric spectroscopy were carried out to investigate molecular dynamics and to test the validity of thermodynamic scaling of two homologous compounds of pharmaceutical activity: itraconazole and ketoconazole in the wide range of thermodynamic conditions. The pressure coefficients of the glass transition temperature (dTg /dp) for itraconazole and ketoconazole were determined to be equal to 183 and 228 K/GPa, respectively. However, for itraconazole, the additional transition to the nematic phase was observed and characterized by the pressure coefficient dTn /dp = 258 K/GPa. From PVT and dielectric data, we obtained that the liquid-nematic phase transition is governed by the relaxation time since it occurred at constant τ α = 10−5 s. Furthermore, we plotted the obtained relaxation times as a function of T −1 v −γ , which has revealed that the validity of thermodynamic scaling with the γ exponent equals to 3.69 ± 0.04 and 3.64 ± 0.03 for itraconazole and ketoconazole, respectively. Further analysis of the scaling parameter in itraconazole revealed that it unexpectedly decreases with increasing relaxation time, which resulted in dramatic change of the shape of the thermodynamic scaling master curve. While in the case of ketoconazole, it remained the same within entire range of data (within experimental uncertainty). We suppose that in case of itraconazole, this peculiar behavior is related to the liquid crystals’ properties of itraconazole molecule.
    Full-text · Article · Jun 2015 · The Journal of Chemical Physics
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    ABSTRACT: This study presents an investigation of the electrical and thermal conductivities of composites based on an ethylene vinyl acetate (EVA) copolymer matrix and nanostructured expanded graphite (EG). To improve the EG dispersion in EVA, EG sheets were modified by treating them with the anionic surfactant sodium dodecyl sulphate (SDS) in water. The modified SDS-EG platelets, after being filtered and dried, were melt-mixed with EVA to prepare the composites. Finally, both EVA/EG and EVA/SDS-EG composites were subjected to 50 kGy electron beam (EB) irradiation. SEM images confirm that the irradiated EVA/EG samples had improved interfacial adhesion, while the irradiated EVA/SDS-EG samples showed even better interfacial adhesion. The gel contents of the irradiated samples without and with SDS treatment increased with increase in EG loading. The EVA/EG composites exhibited a sharp transition from an insulator to a conductor at an electrical percolation threshold of 8 wt %, but with SDS-EG the electrical conductivity was extremely low, showing no percolation up to 10 wt % of filler. The EB irradiation had no influence on electrical conductivity. The thermal conductivity linearly increased with EG content, and this increase was more pronounced in the case of SDS-EG, but decreased after EB irradiation. The thermal properties were little influenced by EB irradiation, while better polymer–filler interaction and better filler dispersion as a result of SDS treatment, and the EB irradiation initiated formation of a cross-linked network, had a positive effect on the tensile properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42396.
    Full-text · Article · May 2015 · Journal of Applied Polymer Science
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    Full-text · Conference Paper · Apr 2015
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    M. Valentini · F. Piana · J. Pionteck · F.R. Lamastra · F. Nanni
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    ABSTRACT: Nanocomposite materials based on commercial thermoplastic polyurethane (TPU) loaded with exfoliated graphite (EG) in concentration between 0 -20 wt.% have been prepared with EG via melt mixing and compression moulding. The materials’ electromagnetic properties have been measured with wave-guide technique between 8.2 and 12.3 GHz. They had shown a clear proportional dependence of complex permittivity with EG content. Above 16 wt.% permittivity becomes frequency dependent. These results are discussed in view of material microstructure by means of scanning electron microscope (SEM) observations. Samples, with 20 wt.% EG and 4mm thick, show an average value of -20 dB of shielding effectiveness (SE), which make them suitable as shielding material for commercial application. Simulations of metal backed configuration showed that important narrowband EM absorption (> -15 dB) can be achieved at 1mm thickness, while multilayer structures are necessary to obtain EM broadband absorption (> -10 dB between 8.5 and 12 GHz) can be achieved in 6 mm thick samples
    Full-text · Article · Mar 2015 · Composites Science and Technology
  • Suneel Kumar Srivastava · Jürgen Pionteck
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    ABSTRACT: Graphite oxide, also referred as graphitic oxide or graphitic acid, is an oxidized bulk product of graphite with a variable composition. However, it did not receive immense attention until it was identified as an important and easily obtainable precursor for the preparation of graphene. This inspired many researchers to explore facts related to graphite oxide in exploiting its fascinating features. The present article culminates up-dated review on different preparative methods, morphology and characterization of physical/chemical properties of graphite oxide by XRD, XPS, FTIR, Raman, NMR, UV-visible, and DRIFT analyses. Finally, recent developments on intercalation and applications of GO in multifaceted areas of catalysis, sensor, supercapacitors, water purification, hydrogen storage and magnetic shielding etc. has also been reviewed.
    No preview · Article · Mar 2015 · Journal of Nanoscience and Nanotechnology
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    ABSTRACT: With the goal to obtain material combining electrical and thermal conductivity at low filler loadings, composites based on polypropylenes (PP) and expanded graphite (EG) have been prepared. The effects of matrix viscosity and of coating the EG particles with polypyrrole (PPy, EG/PPy = 37.5/62.5 by weight) on the EG dispersibility and formation of percolation structures have been analyzed. When increasing the EG amount from 6 to 8 wt %, the electrical conductivity of PP/EG composites increased by 7–9 orders of magnitude, independent of matrix viscosity. When EG-PPy is added, percolation was observed between 8 and 12 wt % EG-PPy (3 and 4.5 wt % EG) in case of PP with higher viscosity and 6 wt % EG (2.25 wt % EG) in case of PP with lower viscosity, exhibiting a strong synergistic effect of EG and PPy in the latter case. In contrast, PPy does not contribute to reduction of thermal percolation concentration. Thermal percolation is observed at 8 wt % EG in PP/EG composites, but no percolation was found in PP/EG-PPy composites with EG-PPy contents of up to 20 wt %, corresponding to 7.5 wt % EG. Analyzing the melt rheology it becomes clear that the contribution of PPy to the formation of a filler network is strongly dependent on the matrix viscosity. The comparison of thermal, electrical and rheological percolation reveals that PPy participates in electron transport reducing the electrical percolation but not to heat transport. Overall, we found a good correlation between electrical, thermal, and melt rheological percolation concentrations. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41994.
    Full-text · Article · Feb 2015 · Journal of Applied Polymer Science
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    Shale J. Sefadi · Adriaan S. Luyt · Jürgen Pionteck
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    ABSTRACT: The influence of expanded graphite (EG) and sodium dodecyl sulfate (SDS) modified EG on the structure, thermal stability, and mechanical properties of ethylene vinyl acetate (EVA) was investigated in this study. The EVA filled with EG platelets, with and without anionic SDS modification, was prepared by melt mixing using a Brabender Plastograph mixer. The extent of dispersion and morphology of the composites were characterized using scanning electron microscopy (SEM), optical microscopy (OM), and X-ray diffraction (XRD). The optical microscopy results show better distribution of the modified EG platelets in the EVA matrix, while the SEM results show an improved interfacial adhesion between the polymer and the SDS-EG particles. Both the EVA18 copolymer and the EG platelets have monoclinic phases, and both EG and SDS do not seem to have any influence on the melting and crystallization behavior of the EVA18. The addition of EG enhanced the thermal stability of EVA18, and this stabilizing influence was further improved when the EG was treated with SDS. All the tensile properties of EVA/EG improved after surface modification. The storage modulus of EVA generally increased with increasing both the unmodified EG and the SDS modified EG content. There was a shift in the Tg to higher temperatures with an increase in both the EG and modified EG content. The α-relaxation peak in the SDS modified EG curves was less intense than the β-relaxation peak, even for the untreated EG composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41352.
    Full-text · Article · Jan 2015 · Journal of Applied Polymer Science
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    ABSTRACT: To solve a long-standing problem of condensed matter physics with determining a proper description of the thermodynamic evolution of the time scale of molecular dynamics near the glass transition, we extend the well-known Adam-Gibbs model to describe the temperature-volume dependence of structural relaxation times, ${\tau}_{\alpha} (T,V)$. We employ the thermodynamic scaling idea reflected in the density scaling power law, ${\tau}_{\alpha}=f(T^{-1} V^{-\gamma } ) $, recently acknowledged as a valid unifying concept in the glass transition physics, to discriminate between physically relevant and irrelevant attempts at formulating the temperature-volume representations of the Adam-Gibbs model. As a consequence, we determine a straightforward relation between the structural relaxation time ${\tau}_{\alpha}$ and the configurational entropy $S_c$, giving evidence that also $S_c (T,V)=g(T^{-1} V^{-\gamma} )$ with the exponent {\gamma} that enables to scale ${\tau}_{\alpha} (T,V)$. This important finding has meaningful implications for the linkage between thermodynamics and molecular dynamics near the glass transition, because it implies that ${\tau}_{\alpha}$ can be scaled with $S_c$.
    Full-text · Article · Jan 2015 · Scientific Reports
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    ABSTRACT: The elastomeric composites using styrene butadiene rubber (SBR) as the polymeric matrix with two types of carbon nanofillers, carbon black and carbon nanotubes, are prepared by melt mixing with the aim to use them as sensors of organic gases for monitoring industrial environments. The prepared composites contain various amounts of conducting nanofillers and are cross-linked before examination for gas sensing. The electrical conductivity of the prepared composites is measured and the percolation threshold is calculated for both types of composites. The first aim is to determine compositions slightly above the percolation threshold for later testing of the sensing properties. Swelling/deswelling experiments have also been performed. The dispersion of conducting fillers in SBR matrix is studied by scanning and transmission electron microscopy techniques, and the mechanical properties of the pure matrix and all prepared composites are determined by tensile testing. Three organic gases, toluene, tetrahydrofuran, and n-hexane, in various mixtures with air are used to examine the ability of the prepared composites to react in their presence by changing the electrical properties. Cyclability of the sensing performance of the composites is also examined. Sensing results reveal the suitability of the prepared SBR-based materials as sensors for harmful solvents and gases widely used in industry.
    No preview · Article · Jan 2015 · Macromolecular Chemistry and Physics
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    Saheli Roy · Suneel Kumar Srivastava · Jürgen Pionteck · Vikas Mittal
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    ABSTRACT: Multiwalled carbon nanotube (MWCNT)–chemically reduced graphene oxide (CRGO) hybrid in different weight ratios were prepared by solution mixing. MWCNT–CRGO (1:1) hybrid exhibited better dispersion stability in dry THF and characterized. Subsequently, it was used as reinforcing filler in thermoplastic polyurethane (TPU) nanocomposites by solution intercalation. Further investigations showed that 0.25 and 0.50 wt.-% MWCNT–CRGO (1:1) loaded TPU exhibit significant improvement in thermal stability (40 °C at 50% weight loss) and storage modulus (206% at 50 °C) respectively. This is attributed to homogeneous dispersion and strong interfacial interaction between TPU and filler.
    Full-text · Article · Dec 2014 · Macromolecular Materials and Engineering
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    Saheli Roy · Suneel Kumar Srivastava · Jürgen Pionteck · Vikas Mittal
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    ABSTRACT: Montmorillonite (MMT)–multiwalled carbon nanotube (MWCNT) hybrids were prepared in different weight ratios by simple dry grinding method and characterized. Subsequently, MMT–MWCNT (1:1) hybrid was used as reinforcing filler in developing thermoplastic polyurethane (TPU) nanocomposites by solution blending method. Thermogravimetric analysis showed that 0.25 wt% hybrid-loaded TPU nanocomposite exhibited maximum enhancement of 31°C corresponding to 50 wt% loss in thermal stability when compared with neat TPU. Differential scanning calorimetry of this composite also indicated that its crystallization and melting temperatures are enhanced by 37 and 13°C, respectively. Mechanical data showed that tensile strength and Young's modulus of 0.50 wt% filled TPU were maximum improved by 57 and 87.5%, respectively. Dynamic mechanical analysis (DMA) measurements indicated 174% (50°C) improvement in storage modulus of 0.50 wt% hybrid-loaded TPU. Such improvements in thermal and mechanical properties have been attributed to homogeneous dispersion, strong interfacial interaction, and synergistic effect. POLYM. COMPOS., 2014. © 2014 Society of Plastics Engineers
    Full-text · Article · Dec 2014 · Polymer Composites
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    ABSTRACT: The fragility parameter has been acknowledged as one of the most important characteristics of glass-forming liquids. We show that the mystery of the dramatic change in molecular dynamics of systems approaching the glass transition can be better understood by the high pressure study of fragility parameters defined in different thermodynamic conditions. We formulate and experimentally confirm a few rules obeyed by the fragility parameters, which are also rationalized by the density scaling law and its modification suggested for associated liquids. In this way, we successfully explore and gain a new insight into the pressure effect on molecular dynamics of van der Waals liquids, polymer melts, ionic liquids, and hydrogen-bonded systems near the glass transition.
    No preview · Article · Oct 2014 · The Journal of Chemical Physics
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    ABSTRACT: Multiwalled carbon nanotubes (CNT) were modified via the non-covalent approach using anodic surfactants dodecylbenzenesulfonic acid (DBSA) and poly(ethylene glycol) n-alkyl 3-sulfopropyl ether potassium salt and cationic surfactant cetyltrimethylammonium bromide (CTAB). These surfactants were used individually or as DBSA/CTAB mixtures. Surface modification was ultrasonically-assisted with a control over sonication power (64 or 360 W). The surface properties of modified CNT particles were determined by X-ray photoelectron spectroscopy and scanning electron microscopy. The electrical conductivities of unmodified CNT, particles treated by ultrasound, and CNT modified with surfactants were measured. Thermogravimetric analysis was used to determine the mass loading of surfactants after drying. The highest increase in conductivity was reached when CNT were treated solely with the anionic surfactant DBSA under the influence of soft ultrasound. This work shows conclusively that ultrasound-assisted modification of CNT by surfactants is a simple and efficient approach to prepare surface modified and highly conductive CNT, provided that physical (ultrasonic) and chemical (surfactants) treatments are concomitantly controlled. Copyright © 2014 John Wiley & Sons, Ltd.
    No preview · Article · Oct 2014 · Surface and Interface Analysis
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    ABSTRACT: There is no abstract available for this article.
    Preview · Article · Aug 2014 · The Journal of Chemical Physics
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    ABSTRACT: In this work we examine, for the first time, the molar conductivity behavior of the deeply supercooled room temperature ionic liquid [C4mim][NTf2] in the temperature, pressure and volume thermodynamic space in terms of density scaling (TV(γ))(-1) combined with the equation of state (EOS). The exponent γσ determined from the Avramov model analysis is compared with the coefficient obtained from the viscosity studies carried out at moderate temperatures. Therefore, the experimental results presented herein provide the answer to the long-standing question regarding the validity of thermodynamic scaling of ionic liquids over a wide temperature range, i.e. from the normal liquid state to the glass transition point. Finally, we investigate the relationship between the dynamic and thermodynamic properties of [C4mim][NTf2] represented by scaling exponent γ and Grüneisen constant γG, respectively.
    No preview · Article · Aug 2014 · Physical Chemistry Chemical Physics

Publication Stats

3k Citations
404.97 Total Impact Points

Institutions

  • 1995-2015
    • Leibniz Institute of Polymer Research Dresden
      • Max Bergmann Center for Biomaterials
      Dresden, Saxony, Germany
  • 2004
    • National Academy of Sciences of Belarus
      Myenyesk, Minsk, Belarus
  • 2001
    • Slovak Academy of Sciences
      • Polymer Institute of Slovak Academy of Sciences
      Presburg, Bratislavský, Slovakia