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Dr. Beate Krause
Leibniz-Institut of Polymerforschung Dresden e.V.

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0 Dispersion
0 Mechanical Behavior of Materials
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Journal article
Published: 28 April 2021 in Nanomaterials
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The present study investigates how the formation of melt-mixed immiscible blends based on PA6/SAN and PA6/PMMA filled with single walled nanotubes (SWCNTs) affects the thermoelectric (TE) properties. In addition to the detailed investigation of the blend morphology with compositions between 100/0 wt.% and 50/50 wt.%, the thermoelectric properties are investigated on blends with different SWCNT concentrations (0.25–3.0 wt.%). Both PA6 and the blend composites with the used type of SWCNTs showed negative Seebeck coefficients. It was shown that the PA6 matrix polymer, in which the SWCNTs are localized, mainly influenced the thermoelectric properties of blends with high SWCNT contents. By varying the blend composition, an increase in the absolute Seebeck coefficient, power factor (PF), and figure of merit (ZT) was achieved compared to the PA6 composite which is mainly related to the selective localization and enrichment of SWCNTs in the PA6 matrix at constant SWCNT loading. The maximum PFs achieved were 0.22 µW/m·K2 for PA6/SAN/SWCNT 70/30/3 wt.% and 0.13 µW/m·K2 for PA6/PMMA/SWCNT 60/40/3 wt.% compared to 0.09 µW/m·K2 for PA6/3 wt.% SWCNT which represent increases to 244% and 144%, respectively. At higher PMMA or SAN concentration, the change from matrix-droplet to a co-continuous morphology started, which, despite higher SWCNT enrichment in the PA6 matrix, disturbed the electrical conductivity, resulting in reduced PFs with still increasing Seebeck coefficients. At SWCNT contents between 0.5 and 3 wt.% the increase in the absolute Seebeck coefficient was compensated by lower electrical conductivity resulting in lower PF and ZT as compared to the PA6 composites.

ACS Style

Beate Krause; Alice Liguoro; Petra Pötschke. Blend Structure and n-Type Thermoelectric Performance of PA6/SAN and PA6/PMMA Blends Filled with Singlewalled Carbon Nanotubes. Nanomaterials 2021, 11, 1146 .

AMA Style

Beate Krause, Alice Liguoro, Petra Pötschke. Blend Structure and n-Type Thermoelectric Performance of PA6/SAN and PA6/PMMA Blends Filled with Singlewalled Carbon Nanotubes. Nanomaterials. 2021; 11 (5):1146.

Chicago/Turabian Style

Beate Krause; Alice Liguoro; Petra Pötschke. 2021. "Blend Structure and n-Type Thermoelectric Performance of PA6/SAN and PA6/PMMA Blends Filled with Singlewalled Carbon Nanotubes." Nanomaterials 11, no. 5: 1146.

Research article
Published: 08 January 2021 in Industrial & Engineering Chemistry Research
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As the field of 3D printing continues to enable the fabrication of biomedical materials and devices, there is increasing demand for the development of biocompatible functional materials with tailorable properties. Here, we utilized a desktop 3D printer to fabricate porous structures of electrically conductive polymer composites comprised of multiwalled carbon nanotubes (MWCNTs) in a matrix of polyhydroxybutyrate (PHB). PHB is a biocompatible, biodegradable, and piezoelectric polymer. The MWCNTs were melt-mixed in amounts from 0.25 to 5 wt % in PHB from two different suppliers with slightly different physical properties. The nanomaterial dispersion, morphology, electrical, thermal, and mechanical properties, and the crystallization behavior of both types of composites were investigated. A good dispersion at the macro- and microscale was observed in both types of composites. Electrical percolation threshold ranges of 0.25–0.5 wt % and 0.5–0.75 wt % were found for composites made with the two different types of PHB. The addition of MWCNTs resulted in an increase of Young’s modulus and decrease of strain at break for both composites. The processability of the materials was demonstrated by 3D printing both stretchable meandering conductive traces and well-defined pore structure scaffolds. Biocompatibility tests were performed with MRC-5 cells and showed that the materials lack cytotoxicity. These results show the potential of these electrically conductive materials for use in biomedical electronic devices or as electro-active scaffolds for tissue regeneration applications, which require biocompatible, porous materials with microscaled architectures.

ACS Style

Li Dan; Qiuli Cheng; Ravin Narain; Beate Krause; Petra Pötschke; Anastasia Elias. Three-Dimensional Printed and Biocompatible Conductive Composites Comprised of Polyhydroxybutyrate and Multiwalled Carbon Nanotubes. Industrial & Engineering Chemistry Research 2021, 60, 885 -897.

AMA Style

Li Dan, Qiuli Cheng, Ravin Narain, Beate Krause, Petra Pötschke, Anastasia Elias. Three-Dimensional Printed and Biocompatible Conductive Composites Comprised of Polyhydroxybutyrate and Multiwalled Carbon Nanotubes. Industrial & Engineering Chemistry Research. 2021; 60 (2):885-897.

Chicago/Turabian Style

Li Dan; Qiuli Cheng; Ravin Narain; Beate Krause; Petra Pötschke; Anastasia Elias. 2021. "Three-Dimensional Printed and Biocompatible Conductive Composites Comprised of Polyhydroxybutyrate and Multiwalled Carbon Nanotubes." Industrial & Engineering Chemistry Research 60, no. 2: 885-897.

Journal article
Published: 15 December 2020 in Polymers
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In the present study, melt-mixed composites based of poly (vinylidene fluoride) (PVDF) and fillers with different aspect ratios (carbon nanotubes (CNTs), carbon black (CB)) and their mixtures in composites were investigated whereby compression-molded plates were compared with melt-extruded films. The processing-related orientation of CNTs with a high aspect ratio leads to direction-dependent electrical and mechanical properties, which can be reduced by using mixed filler systems with the low aspect ratio CB. An upscaling of melt mixing from small scale to laboratory scale was carried out. From extruded materials, films were prepared down to a thickness of 50 µm by cast film extrusion under variation of the processing parameters. By combining CB and CNTs in PVDF, especially the electrical conductivity through the film could be increased compared to PVDF/CNT composites due to additional contact points in the sample thickness. The alignment of the fillers in the two directions within the films was deduced from the differences in electrical and mechanical film properties, which showed higher values in the extrusion direction than perpendicular to it.

ACS Style

Beate Krause; Karina Kunz; Bernd Kretzschmar; Ines Kühnert; Petra Pötschke. Effect of Filler Synergy and Cast Film Extrusion Parameters on Extrudability and Direction-Dependent Conductivity of PVDF/Carbon Nanotube/Carbon Black Composites. Polymers 2020, 12, 2992 .

AMA Style

Beate Krause, Karina Kunz, Bernd Kretzschmar, Ines Kühnert, Petra Pötschke. Effect of Filler Synergy and Cast Film Extrusion Parameters on Extrudability and Direction-Dependent Conductivity of PVDF/Carbon Nanotube/Carbon Black Composites. Polymers. 2020; 12 (12):2992.

Chicago/Turabian Style

Beate Krause; Karina Kunz; Bernd Kretzschmar; Ines Kühnert; Petra Pötschke. 2020. "Effect of Filler Synergy and Cast Film Extrusion Parameters on Extrudability and Direction-Dependent Conductivity of PVDF/Carbon Nanotube/Carbon Black Composites." Polymers 12, no. 12: 2992.

Journal article
Published: 08 December 2020 in Batteries
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A hermetic dense polymer-carbon composite-based current collector foil (PCCF) for lithium-ion battery applications was developed and evaluated in comparison to state-of-the-art aluminum (Al) foil collector. Water-processed LiNi0.5Mn1.5O4 (LMNO) cathode and Li4Ti5O12 (LTO) anode coatings with the integration of a thin carbon primer at the interface to the collector were prepared. Despite the fact that the laboratory manufactured PCCF shows a much higher film thickness of 55 µm compared to Al foil of 19 µm, the electrode resistance was measured to be by a factor of 5 lower compared to the Al collector, which was attributed to the low contact resistance between PCCF, carbon primer and electrode microstructure. The PCCF-C-primer collector shows a sufficient voltage stability up to 5 V vs. Li/Li+ and a negligible Li-intercalation loss into the carbon primer. Electrochemical cell tests demonstrate the applicability of the developed PCCF for LMNO and LTO electrodes, with no disadvantage compared to state-of-the-art Al collector. Due to a 50% lower material density, the lightweight and hermetic dense PCCF polymer collector offers the possibility to significantly decrease the mass loading of the collector in battery cells, which can be of special interest for bipolar battery architectures.

ACS Style

Marco Fritsch; Matthias Coeler; Karina Kunz; Beate Krause; Peter Marcinkowski; Petra Pötschke; Mareike Wolter; Alexander Michaelis. Lightweight Polymer-Carbon Composite Current Collector for Lithium-Ion Batteries. Batteries 2020, 6, 60 .

AMA Style

Marco Fritsch, Matthias Coeler, Karina Kunz, Beate Krause, Peter Marcinkowski, Petra Pötschke, Mareike Wolter, Alexander Michaelis. Lightweight Polymer-Carbon Composite Current Collector for Lithium-Ion Batteries. Batteries. 2020; 6 (4):60.

Chicago/Turabian Style

Marco Fritsch; Matthias Coeler; Karina Kunz; Beate Krause; Peter Marcinkowski; Petra Pötschke; Mareike Wolter; Alexander Michaelis. 2020. "Lightweight Polymer-Carbon Composite Current Collector for Lithium-Ion Batteries." Batteries 6, no. 4: 60.

Journal article
Published: 01 August 2020 in Journal of Composites Science
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The increasing complexity of printed circuit boards (PCBs) due to miniaturization, increased the density of electronic components, and demanding thermal management during the assembly triggered the research of innovative solder pastes and electrically conductive adhesives (ECAs). Current commercial ECAs are typically based on epoxy matrices with a high load (>60%) of silver particles, generally in the form of microflakes. The present work reports the production of ECAs based on epoxy/carbon nanomaterials using carbon nanotubes (single and multi-walled) and exfoliated graphite, as well as hybrid compositions, within a range of concentrations. The composites were tested for morphology (dispersion of the conductive nanomaterials), electrical and thermal conductivity, rheological characteristics and deposition on a test PCB. Finally, the ECA’s shelf life was assessed by mixing all the components and conductive nanomaterials, and evaluating the cure of the resin before and after freezing for a time range up to nine months. The ECAs produced could be stored at −18 °C without affecting the cure reaction.

ACS Style

Paulo E. Lopes; Duarte Moura; Loic Hilliou; Beate Krause; Petra Pötschke; Hugo Figueiredo; Ricardo Alves; Emmanuel Lepleux; Louis Pacheco; Maria C. Paiva. Mixed Carbon Nanomaterial/Epoxy Resin for Electrically Conductive Adhesives. Journal of Composites Science 2020, 4, 105 .

AMA Style

Paulo E. Lopes, Duarte Moura, Loic Hilliou, Beate Krause, Petra Pötschke, Hugo Figueiredo, Ricardo Alves, Emmanuel Lepleux, Louis Pacheco, Maria C. Paiva. Mixed Carbon Nanomaterial/Epoxy Resin for Electrically Conductive Adhesives. Journal of Composites Science. 2020; 4 (3):105.

Chicago/Turabian Style

Paulo E. Lopes; Duarte Moura; Loic Hilliou; Beate Krause; Petra Pötschke; Hugo Figueiredo; Ricardo Alves; Emmanuel Lepleux; Louis Pacheco; Maria C. Paiva. 2020. "Mixed Carbon Nanomaterial/Epoxy Resin for Electrically Conductive Adhesives." Journal of Composites Science 4, no. 3: 105.

Journal article
Published: 10 June 2020 in Nanomaterials
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In this work, composites based on epoxy resin and various carbon nanotubes (CNTs) were studied regarding their thermoelectric properties. The epoxy composites were prepared by infiltration of preformed CNT buckypapers. The influence of different types of CNTs on the Seebeck coefficient was investigated, namely lab-made and commercially available multi walled carbon nanotubes (MWCNTs), lab-made nitrogen doped MWCNTs (N-MWCNT) and commercially available single walled carbon nanotubes (SWCNTs). It was found that only by varying the lab-made MWCNT content could both n- and p-type composites be produced with Seebeck coefficients between −9.5 and 3.1 µV/K. The incorporation of N-MWCNTs resulted in negative Seebeck coefficients of −11.4 to −17.4 µV/K. Thus, the Seebeck coefficient of pure SWCNT changed from 37.4 to −25.5 µV/K in the epoxy/1 wt. % SWCNT composite. A possible explanation for the shift in the Seebeck coefficient is the change of the CNTs Fermi level depending on the number of epoxy molecules on the CNT surface.

ACS Style

Katharina Kröning; Beate Krause; Petra Pötschke; Bodo Fiedler. Nanocomposites with p- and n-Type Conductivity Controlled by Type and Content of Nanotubes in Thermosets for Thermoelectric Applications. Nanomaterials 2020, 10, 1 .

AMA Style

Katharina Kröning, Beate Krause, Petra Pötschke, Bodo Fiedler. Nanocomposites with p- and n-Type Conductivity Controlled by Type and Content of Nanotubes in Thermosets for Thermoelectric Applications. Nanomaterials. 2020; 10 (6):1.

Chicago/Turabian Style

Katharina Kröning; Beate Krause; Petra Pötschke; Bodo Fiedler. 2020. "Nanocomposites with p- and n-Type Conductivity Controlled by Type and Content of Nanotubes in Thermosets for Thermoelectric Applications." Nanomaterials 10, no. 6: 1.

Communication
Published: 27 May 2020 in Chemical Communications
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The force exerted by flexible metal–organic framework through expansion was experimentally evaluated for MIL-53(Al).

ACS Style

Pascal Freund; Irena Senkovska; Bin Zheng; Volodymyr Bon; Beate Krause; Guillaume Maurin; Stefan Kaskel. The force of MOFs: the potential of switchable metal–organic frameworks as solvent stimulated actuators. Chemical Communications 2020, 56, 7411 -7414.

AMA Style

Pascal Freund, Irena Senkovska, Bin Zheng, Volodymyr Bon, Beate Krause, Guillaume Maurin, Stefan Kaskel. The force of MOFs: the potential of switchable metal–organic frameworks as solvent stimulated actuators. Chemical Communications. 2020; 56 (54):7411-7414.

Chicago/Turabian Style

Pascal Freund; Irena Senkovska; Bin Zheng; Volodymyr Bon; Beate Krause; Guillaume Maurin; Stefan Kaskel. 2020. "The force of MOFs: the potential of switchable metal–organic frameworks as solvent stimulated actuators." Chemical Communications 56, no. 54: 7411-7414.

Journal article
Published: 28 January 2020 in Journal of Composites Science
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This study describes the application of multi-walled carbon nanotubes that were nitrogen-doped during their synthesis (N-MWCNTs) in melt-mixed polypropylene (PP) composites. Different types of N-MWCNTs, synthesized using different methods, were used and compared. Four of the five MWCNT grades showed negative Seebeck coefficients (S), indicating n-type charge carrier behavior. All prepared composites (with a concentration between 2 and 7.5 wt% N-MWCNTs) also showed negative S values, which in most cases had a higher negative value than the corresponding nanotubes. The S values achieved were between 1.0 μV/K and −13.8 μV/K for the N-MWCNT buckypapers or powders and between −4.7 μV/K and −22.8 μV/K for the corresponding composites. With a higher content of N-MWCNTs, the increase in electrical conductivity led to increasing values of the power factor (PF) despite the unstable behavior of the Seebeck coefficient. The highest power factor was achieved with 4 wt% N-MWCNT, where a suitable combination of high electrical conductivity and acceptable Seebeck coefficient led to a PF value of 6.1 × 10−3 µW/(m·K2). First experiments have shown that transient absorption spectroscopy (TAS) is a useful tool to study the carrier transfer process in CNTs in composites and to correlate it with the Seebeck coefficient.

ACS Style

Beate Krause; Ioannis Konidakis; Mohammad Arjmand; Uttandaraman Sundararaj; Robert Fuge; Marco Liebscher; Silke Hampel; Maxim Klaus; Efthymis Serpetzoglou; Emmanuel Stratakis; Petra Pötschke. Nitrogen-Doped Carbon Nanotube/Polypropylene Composites with Negative Seebeck Coefficient. Journal of Composites Science 2020, 4, 14 .

AMA Style

Beate Krause, Ioannis Konidakis, Mohammad Arjmand, Uttandaraman Sundararaj, Robert Fuge, Marco Liebscher, Silke Hampel, Maxim Klaus, Efthymis Serpetzoglou, Emmanuel Stratakis, Petra Pötschke. Nitrogen-Doped Carbon Nanotube/Polypropylene Composites with Negative Seebeck Coefficient. Journal of Composites Science. 2020; 4 (1):14.

Chicago/Turabian Style

Beate Krause; Ioannis Konidakis; Mohammad Arjmand; Uttandaraman Sundararaj; Robert Fuge; Marco Liebscher; Silke Hampel; Maxim Klaus; Efthymis Serpetzoglou; Emmanuel Stratakis; Petra Pötschke. 2020. "Nitrogen-Doped Carbon Nanotube/Polypropylene Composites with Negative Seebeck Coefficient." Journal of Composites Science 4, no. 1: 14.

Journal article
Published: 15 January 2020 in Journal of Composites Science
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A suitable polymer matrix and well dispersed conducting fillers forming an electrically conducting network are the prime requisites for modern age electromagnetic shield designing. An effective polymer-based shield material is designed that can attenuate 99.9% of incident electromagnetic (EM) radiation at a minimum thickness of

ACS Style

Sourav Biswas; Tanyaradzwa S. Muzata; Beate Krause; Piotr Rzeczkowski; Petra Pötschke; Suryasarathi Bose. Does the Type of Polymer and Carbon Nanotube Structure Control the Electromagnetic Shielding in Melt-Mixed Polymer Nanocomposites? Journal of Composites Science 2020, 4, 9 .

AMA Style

Sourav Biswas, Tanyaradzwa S. Muzata, Beate Krause, Piotr Rzeczkowski, Petra Pötschke, Suryasarathi Bose. Does the Type of Polymer and Carbon Nanotube Structure Control the Electromagnetic Shielding in Melt-Mixed Polymer Nanocomposites? Journal of Composites Science. 2020; 4 (1):9.

Chicago/Turabian Style

Sourav Biswas; Tanyaradzwa S. Muzata; Beate Krause; Piotr Rzeczkowski; Petra Pötschke; Suryasarathi Bose. 2020. "Does the Type of Polymer and Carbon Nanotube Structure Control the Electromagnetic Shielding in Melt-Mixed Polymer Nanocomposites?" Journal of Composites Science 4, no. 1: 9.

Journal article
Published: 13 January 2020 in Energies
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Composites based on the matrix polymer polypropylene (PP) filled with single-walled carbon nanotubes (SWCNTs) and boron-doped SWCNTs (B-SWCNTs) were prepared by melt-mixing to analyze the influence of boron doping of SWCNTs on the thermoelectric properties of these nanocomposites. It was found that besides a significantly higher Seebeck coefficient of B-SWCNT films and powder packages, the values for B-SWCNT incorporated in PP were higher than those for SWCNTs. Due to the higher electrical conductivity and the higher Seebeck coefficients of B-SWCNTs, the power factor (PF) and the figure of merit (ZT) were also higher for the PP/B-SWCNT composites. The highest value achieved in this study was a Seebeck coefficient of 59.7 µV/K for PP with 0.5 wt% B-SWCNT compared to 47.9 µV/K for SWCNTs at the same filling level. The highest PF was 0.78 µW/(m·K2) for PP with 7.5 wt% B-SWCNT. SWCNT macro- and microdispersions were found to be similar in both composite types, as was the very low electrical percolation threshold between 0.075 and 0.1 wt% SWCNT. At loadings between 0.5 and 2.0 wt%, B-SWCNT-based composites have one order of magnitude higher electrical conductivity than those based on SWCNT. The crystallization behavior of PP is more strongly influenced by B-SWCNTs since their composites have higher crystallization temperatures than composites with SWCNTs at a comparable degree of crystallinity. Boron doping of SWCNTs is therefore a suitable way to improve the electrical and thermoelectric properties of composites.

ACS Style

Beate Krause; Viktor Bezugly; Vyacheslav Khavrus; Liu Ye; Gianaurelio Cuniberti; Petra Pötschke. Boron Doping of SWCNTs as a Way to Enhance the Thermoelectric Properties of Melt-Mixed Polypropylene/SWCNT Composites. Energies 2020, 13, 394 .

AMA Style

Beate Krause, Viktor Bezugly, Vyacheslav Khavrus, Liu Ye, Gianaurelio Cuniberti, Petra Pötschke. Boron Doping of SWCNTs as a Way to Enhance the Thermoelectric Properties of Melt-Mixed Polypropylene/SWCNT Composites. Energies. 2020; 13 (2):394.

Chicago/Turabian Style

Beate Krause; Viktor Bezugly; Vyacheslav Khavrus; Liu Ye; Gianaurelio Cuniberti; Petra Pötschke. 2020. "Boron Doping of SWCNTs as a Way to Enhance the Thermoelectric Properties of Melt-Mixed Polypropylene/SWCNT Composites." Energies 13, no. 2: 394.

Journal article
Published: 17 December 2019 in tm - Technisches Messen
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Zusammenfassung Der nach dem Physiker Thomas Johann Seebeck benannte thermoelektrische Effekt ist für alle wesentlichen Metalle hinreichend gut erforscht und wird seit langem unter anderem zur Temperaturmessung mittels Thermoelementen genutzt. Weniger bekannt und erforscht ist dieser Effekt in polymeren Werkstoffen, die aber heute auch in der Sensorindustrie immer mehr an Einfluss gewinnen. Im vorliegenden Artikel wird eine Messanlage beschrieben, die speziell für die Untersuchung des Seebeck-Effektes in polymeren Messobjekten mit dem Ziel aufgebaut wurde, maßgeschneiderte Polymere für sensorische technische Anwendungen zu entwickeln, die den Seebeck-Effekt nutzen. Die besonderen Anforderungen an die Messanlage liegen dabei in der Realisierung konstanter genauer Temperaturquellen.

ACS Style

Wolfgang Jenschke; Mathias Ullrich; Beate Krause; Petra Pötschke. Messanlage zur Untersuchung des Seebeck-Effektes in Polymermaterialien. tm - Technisches Messen 2019, 87, 495 -503.

AMA Style

Wolfgang Jenschke, Mathias Ullrich, Beate Krause, Petra Pötschke. Messanlage zur Untersuchung des Seebeck-Effektes in Polymermaterialien. tm - Technisches Messen. 2019; 87 (7-8):495-503.

Chicago/Turabian Style

Wolfgang Jenschke; Mathias Ullrich; Beate Krause; Petra Pötschke. 2019. "Messanlage zur Untersuchung des Seebeck-Effektes in Polymermaterialien." tm - Technisches Messen 87, no. 7-8: 495-503.

Journal article
Published: 07 December 2019 in Journal of Composites Science
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The aim of this study is to reveal the influences of carbon nanotube (CNT) and polymer type as well as CNT content on electrical conductivity, Seebeck coefficient (S), and the resulting power factor (PF) and figure of merit (ZT). Different commercially available and laboratory made CNTs were used to prepare melt-mixed composites on a small scale. CNTs typically lead to p-type composites with positive S-values. This was found for the two types of multi-walled CNTs (MWCNT) whereby higher Seebeck coefficient in the corresponding buckypapers resulted in higher values also in the composites. Nitrogen doped MWCNTs resulted in negative S-values in the buckypapers as well as in the polymer composites. When using single-walled CNTs (SWCNTs) with a positive S-value in the buckypapers, positive (polypropylene (PP), polycarbonate (PC), poly (vinylidene fluoride) (PVDF), and poly(butylene terephthalate) (PBT)) or negative (polyamide 66 (PA66), polyamide 6 (PA6), partially aromatic polyamide (PARA), acrylonitrile butadiene styrene (ABS)) S-values were obtained depending on the matrix polymer and SWCNT type. The study shows that the direct production of n-type melt-mixed polymer composites from p-type commercial SWCNTs with relatively high Seebeck coefficients is possible. The highest Seebeck coefficients obtained in this study were 66.4 µV/K (PBT/7 wt % SWCNT Tuball) and −57.1 µV/K (ABS/0.5 wt % SWCNT Tuball) for p- and n-type composites, respectively. The highest power factor and ZT of 0.28 µW/m·K2 and 3.1 × 10−4, respectively, were achieved in PBT with 4 wt % SWCNT Tuball.

ACS Style

Beate Krause; Carine Barbier; Juhasz Levente; Maxim Klaus; Petra Pötschke. Screening of Different Carbon Nanotubes in Melt-Mixed Polymer Composites with Different Polymer Matrices for Their Thermoelectrical Properties. Journal of Composites Science 2019, 3, 106 .

AMA Style

Beate Krause, Carine Barbier, Juhasz Levente, Maxim Klaus, Petra Pötschke. Screening of Different Carbon Nanotubes in Melt-Mixed Polymer Composites with Different Polymer Matrices for Their Thermoelectrical Properties. Journal of Composites Science. 2019; 3 (4):106.

Chicago/Turabian Style

Beate Krause; Carine Barbier; Juhasz Levente; Maxim Klaus; Petra Pötschke. 2019. "Screening of Different Carbon Nanotubes in Melt-Mixed Polymer Composites with Different Polymer Matrices for Their Thermoelectrical Properties." Journal of Composites Science 3, no. 4: 106.

Articles
Published: 08 November 2019 in The Journal of Adhesion
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A graphite-modified adhesive was developed in order to simultaneously enhance the thermal conductivity and the strength of an adhesive joint. The thermal conductivity through the joint was investigated by using highly filled PP/graphite composite substrates, which were joined with an epoxy adhesive of different layer thicknesses. Similar measurements were carried out with a constant adhesive layer thickness, whilst applying an epoxy adhesive modified with expanded graphite (EG) (6, 10, and 20 wt%). By reducing the adhesive layer thickness or modifying the adhesive with conductive fillers, a significant increase of the thermal conductivity through the joint was achieved. The examination of the mechanical properties of the modified adhesives was carried out by tensile tests (adhesive only), lap-shear tests, and fracture energy tests (mode 1) with aluminium substrates. Modification of the adhesive with EG led to an increase of the tensile lap-shear strength and the adhesive fracture energy (mode 1) of the joint. In addition, burst pressure tests were performed to determine the strength of the joint in a complex component. The strength of the joint increased with the graphite content in the PP substrate and in the epoxy adhesive.

ACS Style

P. Rzeczkowski; P. Pötschke; M. Fischer; I. Kühnert; B. Krause. Graphite modified epoxy-based adhesive for joining of aluminium and PP/graphite composites. The Journal of Adhesion 2019, 96, 229 -252.

AMA Style

P. Rzeczkowski, P. Pötschke, M. Fischer, I. Kühnert, B. Krause. Graphite modified epoxy-based adhesive for joining of aluminium and PP/graphite composites. The Journal of Adhesion. 2019; 96 (1-4):229-252.

Chicago/Turabian Style

P. Rzeczkowski; P. Pötschke; M. Fischer; I. Kühnert; B. Krause. 2019. "Graphite modified epoxy-based adhesive for joining of aluminium and PP/graphite composites." The Journal of Adhesion 96, no. 1-4: 229-252.

Research article
Published: 12 September 2019 in ACS Applied Materials & Interfaces
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Improving energy dissipation in lightweight polymer nanocomposites to achieve environmentally friendly and mechanically stable structures has reached a limit because of the low-density electrostatic interactions that can be harnessed through the stick-slip mechanism between carbonaceous nanofillers and polymeric chains wrapped around them. In this paper, the atomic friction between the two nanocomposite components is greatly amplified by locally increasing the density of the energetically higher noncovalent bonds. This gives rise to a new material design concept in which crystallite structures, nucleated around the carbonaceous nanofillers, become the source of enhanced energy dissipation. The rheological concept is a nanopiston unit consisting of a carbon nanotube (CNT) as a nanofiller coated with crystallite structures which, upon unconventionally and reversibly overcoming the interfacial interaction forces, monolithically roto-translate from an energetically stable state to the adjacent states. The efficiency of this novel "sliding crystals" mechanism is proven by its higher dissipation capability that turns out to be at least twice as much as that of the conventional CNT/polymer stick-slip within a larger strain range.

ACS Style

Michela Talò; Giulia Lanzara; Beate Krause; Andreas Janke; Walter Lacarbonara. "Sliding Crystals" on Low-Dimensional Carbonaceous Nanofillers as Distributed Nanopistons for Highly Damping Materials. ACS Applied Materials & Interfaces 2019, 11, 38147 -38159.

AMA Style

Michela Talò, Giulia Lanzara, Beate Krause, Andreas Janke, Walter Lacarbonara. "Sliding Crystals" on Low-Dimensional Carbonaceous Nanofillers as Distributed Nanopistons for Highly Damping Materials. ACS Applied Materials & Interfaces. 2019; 11 (41):38147-38159.

Chicago/Turabian Style

Michela Talò; Giulia Lanzara; Beate Krause; Andreas Janke; Walter Lacarbonara. 2019. ""Sliding Crystals" on Low-Dimensional Carbonaceous Nanofillers as Distributed Nanopistons for Highly Damping Materials." ACS Applied Materials & Interfaces 11, no. 41: 38147-38159.

Conference paper
Published: 26 August 2019 in PROCEEDINGS OF PPS-33 : The 33rd International Conference of the Polymer Processing Society – Conference Papers
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Novel material solutions for bipolar plates in fuel cells require adapted ways of joining and sealing technologies. Safe and life time enduring leak-tight contacts must be achieved by automatic processes using reasonable joint forces. A proper sealing should manage such challenges as good ageing properties, excellent leak-tightness, high thermal conductivity and low gas permeability. Hence in this work, adhesive bonding and welding are considered as suitable methods, which can fulfill the requirements mentioned above. Adhesive systems seem to be more easy to apply than conventional sealing (hand layed-up rubber gaskets), e.g. with automatic dispensers. Additionally, the properties of an adhesive joint can be enhanced by a process-specific surface pre-treatment. This work focuses on the characterization of adhesive systems and their joints with highly filled graphite composites. Mechanical properties of the joints were characterized through lap-shear tests. The influence of ageing caused by humidity or acidic solvent at increased temperature on the bond line properties as well as neat adhesive was examined. The thermal conductivities of neat adhesives and through the entire joint were examined. In order to improve above conductivities, roughening, substrate pre-heating, post-curing and various contact pressure weights were applied. Plasma treatment was chosen as surface pre-treatment method for improving substrate’s surface energy. An alternative to bonding is plastic welding, which does not require the use of sealants and adhesives. Based on former study of influences of filler content on the welding process using ultrasonic, hot plate or infrared welding, a welding method for joining the graphite compounds was derived.

ACS Style

P. Rzeczkowski; M. Lucia; A. Müller; M. Facklam; A. Cohnen; P. Schäfer; Ch. Hopmann; T. Hickmann; Petra Pötschke; B. Krause. Development of joining methods for highly filled graphite/PP composite based bipolar plates for fuel cells: Adhesive joining and welding. PROCEEDINGS OF PPS-33 : The 33rd International Conference of the Polymer Processing Society – Conference Papers 2019, 2139, 110003 .

AMA Style

P. Rzeczkowski, M. Lucia, A. Müller, M. Facklam, A. Cohnen, P. Schäfer, Ch. Hopmann, T. Hickmann, Petra Pötschke, B. Krause. Development of joining methods for highly filled graphite/PP composite based bipolar plates for fuel cells: Adhesive joining and welding. PROCEEDINGS OF PPS-33 : The 33rd International Conference of the Polymer Processing Society – Conference Papers. 2019; 2139 (1):110003.

Chicago/Turabian Style

P. Rzeczkowski; M. Lucia; A. Müller; M. Facklam; A. Cohnen; P. Schäfer; Ch. Hopmann; T. Hickmann; Petra Pötschke; B. Krause. 2019. "Development of joining methods for highly filled graphite/PP composite based bipolar plates for fuel cells: Adhesive joining and welding." PROCEEDINGS OF PPS-33 : The 33rd International Conference of the Polymer Processing Society – Conference Papers 2139, no. 1: 110003.

Conference paper
Published: 26 August 2019 in PROCEEDINGS OF PPS-33 : The 33rd International Conference of the Polymer Processing Society – Conference Papers
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Novel material solutions for polymer based bipolar plates in fuel cells require adapted ways to develop suitable material compositions. The common pathway to develop materials with at the same time high electrical as well as thermal conductivity is the use of conductive graphite as filler with contents up to 80-85 wt.%. However, there is a need to develop recipes with maximized conductive behavior at lowest possible content of conductive filler to enhance the mechanical properties and allow good processability. In this study, composites based on polypropylene (PP) and different filler systems were melt-mixed using a lab scale co-rotating twin-screw extruder and compression molded to bipolar type plates. As fillers synthetic (G) or expanded (EG) graphites were incorporated. At the overall filler content of 60 wt.% or 80 wt% part of the graphite was replaced by highly conductive carbon black (CB, 2.5 wt.%, 5.0 wt.%). It was found that the addition of CB significantly reduced the electrical volume as well as the surface resistivity up to values of 0.12 Ω·cm or 4 mΩ/square, respectively. For the values of thermal conductivity the kind and particle size of the selected graphite was important. If expanded graphite was partially replaced by CB, the thermal conductivity of PP/EG+CB composites decreased significantly. Otherwise, the combination of synthetic graphite and CB changed the thermal conductivity of PP composites only marginal at the same overall filler content. For both graphite types the filler with larger particle size resulted in higher thermal conductivity.

ACS Style

Beate Krause; Petra Pötschke; Thorsten Hickmann. Improvement of electrical resistivity of highly filled graphite/PP composite based bipolar plates for fuel cells by addition of carbon black. PROCEEDINGS OF PPS-33 : The 33rd International Conference of the Polymer Processing Society – Conference Papers 2019, 2139, 110006 .

AMA Style

Beate Krause, Petra Pötschke, Thorsten Hickmann. Improvement of electrical resistivity of highly filled graphite/PP composite based bipolar plates for fuel cells by addition of carbon black. PROCEEDINGS OF PPS-33 : The 33rd International Conference of the Polymer Processing Society – Conference Papers. 2019; 2139 (1):110006.

Chicago/Turabian Style

Beate Krause; Petra Pötschke; Thorsten Hickmann. 2019. "Improvement of electrical resistivity of highly filled graphite/PP composite based bipolar plates for fuel cells by addition of carbon black." PROCEEDINGS OF PPS-33 : The 33rd International Conference of the Polymer Processing Society – Conference Papers 2139, no. 1: 110006.

Article
Published: 21 August 2019 in Journal of Applied Polymer Science
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Multiwalled carbon nanotubes (MWCNTs) were modified by an organo‐silane in order to improve their dispersion state and stability in paraffin wax. A family of paraffin‐based phase change material (PCM) composites filled with MWCNTs was prepared with different loadings (0, 0.1, 0.5, and 1 wt%) of pristine MWCNTs and organo‐silane modified MWCNTs (Si‐MWCNT). Structural analyses were performed by means of Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and rheological studies using temperature sweeps. Moreover, phase change transition temperatures and heat of fusion as well as thermal and electrical conductivities of the developed PCM nanocomposites were determined. The SEM micrographs and FTIR absorption bands appearing at approximately 1038 and 1112 cm−1 confirmed the silane modification. Differential scanning calorimetery (DSC) results indicate that the presence of Si‐MWCNTs leads to slightly favorable enhancement in the energy storage capacity at the maximum loading. It was also shown that the thermal conductivity of the PCM nanocomposites, in both solid and liquid phases, increased with increasing the MWCNT content independent of the kind of MWCNTs by up to about 30% at the maximum loading of MWCNTs. In addition, the modification of MWCNTs made the samples completely electrically nonconductive, and the electrical surface resistivity of the PCMs containing pristine MWCNTs decreased with increasing MWCNTs loading. Furthermore, the rheological assessment under consecutive cyclic phase change demonstrated that the samples containing modified MWCNTs are more stable compared to the PCM containing pristine MWCNTs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48428.

ACS Style

Arezoo Avid; Seyed Hassan Jafari; Hossein Ali Khonakdar; Mehdi Ghaffari; Beate Krause; Petra Pötschke. Surface modification of MWCNT and its influence on properties of paraffin/MWCNT nanocomposites as phase change material. Journal of Applied Polymer Science 2019, 137, 1 .

AMA Style

Arezoo Avid, Seyed Hassan Jafari, Hossein Ali Khonakdar, Mehdi Ghaffari, Beate Krause, Petra Pötschke. Surface modification of MWCNT and its influence on properties of paraffin/MWCNT nanocomposites as phase change material. Journal of Applied Polymer Science. 2019; 137 (9):1.

Chicago/Turabian Style

Arezoo Avid; Seyed Hassan Jafari; Hossein Ali Khonakdar; Mehdi Ghaffari; Beate Krause; Petra Pötschke. 2019. "Surface modification of MWCNT and its influence on properties of paraffin/MWCNT nanocomposites as phase change material." Journal of Applied Polymer Science 137, no. 9: 1.

Journal article
Published: 21 June 2019 in Polymers
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Melt-mixed composites based on polypropylene (PP) with various carbon-based fillers were investigated with regard to their thermal conductivity and electrical resistivity. The composites were filled with up to three fillers by selecting combinations of graphite nanoplatelets (GNP), carbon fibers (CF), carbon nanotubes (CNT), carbon black (CB), and graphite (G) at a constant filler content of 7.5 vol%. The thermal conductivity of PP (0.26 W/(m·K)) improved most using graphite nanoplatelets, whereas electrical resistivity was the lowest when using multiwalled CNT. Synergistic effects could be observed for different filler combinations. The PP composite, which contains a mixture of GNP, CNT, and highly structured CB, simultaneously had high thermal conductivity (0.5 W/(m·K)) and the lowest electrical volume resistivity (4 Ohm·cm).

ACS Style

Beate Krause; Piotr Rzeczkowski; Petra Pötschke. Thermal Conductivity and Electrical Resistivity of Melt-Mixed Polypropylene Composites Containing Mixtures of Carbon-Based Fillers. Polymers 2019, 11, 1073 .

AMA Style

Beate Krause, Piotr Rzeczkowski, Petra Pötschke. Thermal Conductivity and Electrical Resistivity of Melt-Mixed Polypropylene Composites Containing Mixtures of Carbon-Based Fillers. Polymers. 2019; 11 (6):1073.

Chicago/Turabian Style

Beate Krause; Piotr Rzeczkowski; Petra Pötschke. 2019. "Thermal Conductivity and Electrical Resistivity of Melt-Mixed Polypropylene Composites Containing Mixtures of Carbon-Based Fillers." Polymers 11, no. 6: 1073.

Accepted manuscript
Published: 16 April 2019 in Smart Materials and Structures
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Here, we report multifunctional polycarbonate (PC)-based conductive polymer composites (CPCs) with outstanding performance manufactured by a simple extrusion process and intended for use in bipolar plate (BPP) applications in polymer electrolyte membrane (PEM) fuel cells. CPCs were developed using a ternary conductive filler system containing carbon nanotube (CNT), carbon fiber (CF), and graphite (G) and by introducing di-allyl phthalate (DAP) as a plasticizer to PC matrix. The samples were fabricated using twin-screw extrusion followed by compression molding and the microstructure, electrical conductivity, thermal conductivity, and mechanical properties were investigated. The results showed a good dispersion of the fillers with some degree of interconnection between dissimilar fillers. The addition of DAP enhanced the electrical conductivity and tensile strength of the CPCs. Due to its plasticizing effect, DAP reduced the processing temperature by 75°C and facilitated the extrusion of CPCs with filler loads as high as 63wt.% (3wt.% CNT, 30wt.% CF, 30wt.% G). Consequently, CPCs with the through-plane electrical, in-plane electrical and thermal conductivities and tensile strength of 4.2S.cm-1, 34.3S.cm-1, 2.9W.m-1.K-1, and 75.4MPa, respectively, were achieved. This combination of properties indicates the potential of PC-based composites enriched with hybrid fillers and plasticizers as an alternative material for bipolar plate application.

ACS Style

Ahmed Naji; Beate Krause; Petra Potschke; Amir Ameli. Extruded polycarbonate/Di-Allyl phthalate composites with ternary conductive filler system for bipolar plates of polymer electrolyte membrane fuel cells. Smart Materials and Structures 2019, 28, 064004 .

AMA Style

Ahmed Naji, Beate Krause, Petra Potschke, Amir Ameli. Extruded polycarbonate/Di-Allyl phthalate composites with ternary conductive filler system for bipolar plates of polymer electrolyte membrane fuel cells. Smart Materials and Structures. 2019; 28 (6):064004.

Chicago/Turabian Style

Ahmed Naji; Beate Krause; Petra Potschke; Amir Ameli. 2019. "Extruded polycarbonate/Di-Allyl phthalate composites with ternary conductive filler system for bipolar plates of polymer electrolyte membrane fuel cells." Smart Materials and Structures 28, no. 6: 064004.

Journal article
Published: 01 April 2019 in Polymers
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The method of measuring electrical volume resistivity in different directions was applied to characterize the filler orientation in melt mixed polymer composites containing different carbon fillers. For this purpose, various kinds of fillers with different geometries and aspect ratios were selected, namely carbon black (CB), graphite (G) and expanded graphite (EG), branched multiwalled carbon nanotubes (b-MWCNTs), non-branched multiwalled carbon nanotubes (MWCNTs), and single-walled carbon nanotubes (SWCNTs). As it is well known that the shaping process also plays an important role in the achieved electrical properties, this study compares results for compression molded plates with random filler orientations in the plane as well as extruded films, which have, moreover, conductivity differences between extrusion direction and perpendicular to the plane. Additionally, the polymer matrix type (poly (vinylidene fluoride) (PVDF), acrylonitrile butadiene styrene (ABS), polyamide 6 (PA6)) and filler concentration were varied. For the electrical measurements, a device able to measure the electrical conductivity in two directions was developed and constructed. The filler orientation was analyzed using the ratio σin/th calculated as in-plane conductivity σin-plane (σin) divided by through-plane conductivity σthrough-plane (σth). The ratio σin/th is expected to increase with more pronounced filler orientation in the processing direction. In the extruded films, alignment within the plane was assigned by dividing the in-plane conductivity in the extrusion direction (x) by the in-plane conductivity perpendicular to the extrusion direction (y). The conductivity ratios depend on filler type and concentration and are higher the higher the filler aspect ratio and the closer the filler content is to the percolation concentration.

ACS Style

Karina Kunz; Beate Krause; Bernd Kretzschmar; Levente Juhasz; Oliver Kobsch; Wolfgang Jenschke; Mathias Ullrich; Petra Pötschke. Direction Dependent Electrical Conductivity of Polymer/Carbon Filler Composites. Polymers 2019, 11, 591 .

AMA Style

Karina Kunz, Beate Krause, Bernd Kretzschmar, Levente Juhasz, Oliver Kobsch, Wolfgang Jenschke, Mathias Ullrich, Petra Pötschke. Direction Dependent Electrical Conductivity of Polymer/Carbon Filler Composites. Polymers. 2019; 11 (4):591.

Chicago/Turabian Style

Karina Kunz; Beate Krause; Bernd Kretzschmar; Levente Juhasz; Oliver Kobsch; Wolfgang Jenschke; Mathias Ullrich; Petra Pötschke. 2019. "Direction Dependent Electrical Conductivity of Polymer/Carbon Filler Composites." Polymers 11, no. 4: 591.