Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-58094 Vortrag Trappe, Volker; Kalinka, Gerhard; Loose, Florian Carbon fibre composites exemplarily research at BAM Lightweighting as a cross-cutting technology contributes significantly to achieve the European Green Deal goals. Based on, but not limited to, advanced materials and production technologies, the demand for natural resources and CO2 emmissions are reduced by lightweighting during production, as well as use phase. Therefore, lightweighting is a crucial transformation technology assisting in decoupling economic growth from resource consumption. In this manner, lightweighting contributes significantly as a key technology of relevance for many industrial sectors such as energy, mobility, and infrastructure, towards resource efficiency, climate action and economic strength, as well as a resilient Europe. To strengthen international partnerships, addressing global issues of today at the edge of science with high performance lightweight material based on carbon fibers, an overview about the BAM expertise in carbon fiber reinforced materials is given. 2023 Meeting KCarbon Berlin, Germany 15.06.2023 2023-10-27 OPUS4-39128 Zeitschriftenartikel Kalinka, Gerhard; ElAbshihy, K. Circumventing boundary effects while characterizing epoxy/copper interphases using nanoindentation Characterization of the size and mechanical properties of interphases is essential when designing multicomponent materials. When nanoindentation is used to investigate the size and mechanical properties of an interphase, a common challenge is that the indenter or the stress zone formed around it are often restricted by the reinforcement, making it difficult to distinguish the mechanical property variations caused by the interphase itself from those caused by the boundary effect. In this work, a testing system was developed that allows determining the indent affected zone and accounting for it in the interphase measurements of an epoxy/Cu system. Using finite element analysis, we confirmed the validity of the proposed system. Nanoindentation was used to investigate the Interphase between copper and two different epoxy systems; amine-cured and anhydride-cured. Nanoindentation results showed that a copper layer that is only 10 nm thick still exhibits a constriction effect on the indentations in its vicinity. The amine-cured epoxy did not show any sign of interphase existence using the introduced method. However, a soft interphase with a thickness of ~1.7 μm was measured on theanhydride-cured epoxy. Furthermore, we show that the proposed system can be used to determine the interphase thickness as well as its relative mechanical properties regardless of the indentation depth. This system can be further used for investigating other polymer/metal interphases to better understand the factors influencing them, thus helping engineer the interphase size and properties to enhance composite performance. UK Taylor & Francis 2017 Composite Interfaces 24 9 833 848 10.1080/09276440.2017.1286878 2017-02-09 OPUS4-59053 Vortrag Kalinka, Gerhard Testing the fibre matrix interface of short glass fibre reinforced PMCs with using the push out technique With this presentation, the push-out technique is explained. The focus of the experimental work is on the characterization of the fiber-matrix interface of short fiber reinforced composites. The reinforcing component was glass fibers and the matrix polymer was PA6.6 and PPA. It is demonstrated for the first time that the push-out technique ca be applied on injection molded short fiber PMC and is sensitive to the mechanical interface properties. Further studies are planned on the influence of multiple processing, the temperature and humidity. 2023 Composirtes United Workshop „Fiber Matrix Interphases“ Online meeting 09.11.2023 09.11.2023 2023-12-07 OPUS4-45433 Zeitschriftenartikel Taketa, I.; Kalinka, Gerhard; Gorbatikh, L.; Lomov, S.; Verpoest, I. Influence of cooling rate on the properties of carbon fiber unidirectional composites with polypropylene, polyamide 6, and polyphenylene sulfide matrices The longitudinal and transverse strength of three unidirectional thermoplastic prepreg systems: carbon fiber/polypropylene (CF/PP), polyamide 6 (CF/PA6), and polyphenylene sulfide (CF/PPS) are studied and analytical formulas are proposed for the estimation of matrix and fiber/matrix interface properties from composites properties. Since the matrices are semi-crystalline thermoplastics, the influence of cooling rate on the strength is statistically evaluated. While the 0° tensile strength is found to be independent of the cooling rate, the 90° tensile strength is strongly influenced by the matrix type and cooling rate. The matrix modulus increases as the cooling rate is decreased; the degree of crystallinity also increases. The matrix residual stress, interfacial shear strength, and mode II interlaminar fracture toughness are also found to depend on the cooling rate, with the trends different for different matrices. London Taylor & Francis The Japan Society for Composite Materials 2020 Advanced composite materials 29 1 101 113 10.1080/09243046.2019.1651083 2018-07-11 OPUS4-4703 Posterpräsentation Kalinka, Gerhard Micro indentation near stiff-soft phase boundaries 2004 Polydays 2004 Polydays 2004 Potsdam, Germany 2004-10-04 2004-10-06 2016-02-19 OPUS4-13804 Vortrag Kalinka, Gerhard Testing the interface shear strength of carbon fibre reinforced composites 2006 Polydays 2006 Polydays 2006 Berlin, Germany 2006-10-04 2016-02-19 OPUS4-12107 Posterpräsentation Kalinka, Gerhard Monitoring the interface crack propagation with micromechanical test devices 2001 Interfacial Phenomena in Composite Materials Interfacial Phenomena in Composite Materials Berlin, Germany 2001-01-28 2001-02-02 2016-02-19 OPUS4-12004 Zeitschriftenartikel Kalinka, Gerhard; Hinrichsen, G. Two-dimensional computer simulation of spherulite formation by branching lamellae Weinheim Wiley-VCH Verl. 1997 Acta polymerica 48 256 261 2016-02-19 OPUS4-12102 Posterpräsentation Hampe, Andreas An Advanced Indentation Technique for the Characterization of the Fibre-Matrix Interface 1997 Gordon Conference on Composites Gordon Conference on Composites San Buenaventura, CA, USA 1997-01-05 1997-01-09 2016-02-19 OPUS4-12108 Posterpräsentation Kalinka, Gerhard Energy Quantification of Interface Debonding Processes Using 'Stiff' Test Devices 2001 Gordon Conference on Composite Materials Gordon Conference on Composite Materials San Buenaventura, CA, USA 2001-01-28 2001-02-02 2016-02-19 OPUS4-11989 Zeitschriftenartikel Schulz, Eckhard; Kalinka, Gerhard; Meretz, S.; Hampe, Andreas Pull-out of Single Fibres München Hanser 1994 Kunststoffe : bilingual edition, German + English 84 5 25 26 2016-02-19 OPUS4-12085 Vortrag Hinrichsen, G. Computer simulation of spherulitic formation and crystallization in semicrystalline polymers 1995 Europhysics Conference on Macromolecular Physics Europhysics Conference on Macromolecular Physics Prague, Czech Republic 1995-07-17 1995-07-20 2016-02-19 OPUS4-4704 Posterpräsentation Kalinka, Gerhard Micro indentation near stiff-soft boundaries 2004 "Nanomech5, 5th European Symposium on nano-Mechanical Testing" "Nanomech5, 5th European Symposium on nano-Mechanical Testing" Hückelhoven, Germany 2004-09-07 2004-09-09 2016-02-19 OPUS4-12100 Posterpräsentation Kalinka, Gerhard Energy based characterization of the fiber-matrix interface unsing the pull-out and the push-out test 1997 Micro Mat '97 Micro Mat '97 Berlin, Germany 1997-04-16 1997-04-18 2016-02-19 OPUS4-12093 Vortrag Kalinka, Gerhard Energy orientated data interpretation of pull-out and push-out test for the investigation of residual stresses 1999 Interface Phenomena in Composite Materials Interface Phenomena in Composite Materials Berlin, Germany 1999-09-08 1999-09-10 2016-02-19 OPUS4-12103 Posterpräsentation Kalinka, Gerhard Interfacial properties and their determination by using stiffness optimized test devices 1997 Workshop on Micro-Mechanics Measurement Technologies, NIST Workshop on Micro-Mechanics Measurement Technologies, NIST Gaithersburg, MD, USA 1997-05-28 1997-05-30 2016-02-19 OPUS4-11999 Zeitschriftenartikel Kalinka, Gerhard; Boro, I.; Augustin, G.; Hampe, Andreas; Hinrichsen, G. Fatigue Behaviour of High-Performance Fibre-Reinforced Composites with a Thermoplastic Matrix Munich Hanser 1990 Kunststoffe / German plastics 80 5 36 38 2016-02-19 OPUS4-12098 Posterpräsentation Kalinka, Gerhard Energy Dissipation of the Fibre-Matrix Debonding Process Investigated with the Indentation Technique 1995 Interfacial Phenomena of Composite Materials IPCM'95 Interfacial Phenomena of Composite Materials IPCM'95 Eindhoven, Netherlands 1995-09-11 1995-09-13 2016-02-19 OPUS4-4702 Vortrag Kalinka, Gerhard A model of spherulitic crystallization based on growing lameallae 2004 9th Microsymposium of Electron Microscopy in Materials Science 9th Microsymposium of Electron Microscopy in Materials Science Lutherstadt Wittenberg, Germany 2004-05-06 2004-05-07 2016-02-19 OPUS4-7506 Vortrag Kalinka, Gerhard Micro indentation and scratch tests for surface characterisation 2001 XXII. Donauländergespräche über die natürliche und künstliche Alterung von Polymeren XXII. Donauländergespräche über die natürliche und künstliche Alterung von Polymeren Berlin, Germany 2001-09-17 2001-09-18 2016-02-19 OPUS4-12087 Vortrag Hampe, Andreas Energy based characterization of the fibre-matrix interface using the pull-out and push-in test 1997 Interfacial Phenomena in Composite Materials 97 Interfacial Phenomena in Composite Materials 97 Eger, Hungary 1997-03-01 1997-09-03 2016-02-19 OPUS4-12089 Vortrag Kalinka, Gerhard Friction Measurement on fiber reinforced polymer composites with using the indentation technique 1998 European Conference on Composite Materials ECCM-8 European Conference on Composite Materials ECCM-8 Naples, Italy 1998-06-03 1998-06-06 2016-02-19 OPUS4-12095 Posterpräsentation Hampe, Andreas An Advanced Equipment for Single-Fibre Pull-Out test designed to monitor the fracture process 1993 Interfacial Phenomena in Composite Materials Interfacial Phenomena in Composite Materials Cambridge, England 1993-09-13 1993-09-15 2016-02-19 OPUS4-11988 Zeitschriftenartikel Hampe, Andreas; Kalinka, Gerhard; Meretz, S.; Schulz, Eckhard An advanced equipment for single-fibre pull-out test designed to monitor the fracture process Guildford, Surrey Butterworth-Heinemann 1995 Composites 26 1 40 46 2016-02-19 OPUS4-5908 Vortrag Hampe, Andreas The Fracture Process in the Fibre/Matrix Interphase 1994 The Fifth International Conference on Composite Interfaces The Fifth International Conference on Composite Interfaces Gothenburg, Sweden 1994-07-20 1994-07-23 2016-02-19 OPUS4-12101 Posterpräsentation Kalinka, Gerhard Energy based characterization of the fiber-matrix interface unsing the pull-out and the push-out test 1997 Interfacial Phenomena of Composite Materials IPCM'97 Interfacial Phenomena of Composite Materials IPCM'97 Eger, Hungary 1997-09-01 1997-09-03 2016-02-19 OPUS4-12009 Vortrag Hampe, Andreas The Fracture Process in the Interphase Investigated by the Single Fiber Pull-out Test 1994 Composites Testing and Standardisation ECCM-CTS 2 Composites Testing and Standardisation ECCM-CTS 2 Hamburg, Germany 1994-09-13 1994-09-15 2016-02-19 OPUS4-12086 Vortrag Kalinka, Gerhard Characterization of the fibre-matrix interface with the indentation technique 1996 6th International Conference on Composite Interfaces (ICCI-VI) 6th International Conference on Composite Interfaces (ICCI-VI) Zichron Ya'akov, Israel 1996-05-05 1996-05-08 2016-02-19 OPUS4-11991 Zeitschriftenartikel Auer, C.; Kalinka, Gerhard; Krause, T.; Hinrichsen, G. Crystallization Kinetics of Pure and Fiber-Reinforced Poly(phenylene Sulfide) Hoboken, NJ Wiley InterScience 1994 Journal of applied polymer science 51 407 413 2016-02-19 OPUS4-11992 Zeitschriftenartikel Krause, T.; Kalinka, Gerhard; Auer, C.; Hinrichsen, G. Computer Simulation of Crystallization Kinetics in FIber-Reinforced Composites Hoboken, NJ Wiley InterScience 1994 Journal of applied polymer science 51 399 406 2016-02-19 OPUS4-5929 Vortrag Hampe, Andreas Measurement of the Interfacial Toughness in Composites by Micromechanical Experiments 1997 4th Arab International Conference on Polymer Science & Technology 4th Arab International Conference on Polymer Science & Technology Cairo, Egypt 1997-09-08 1997-09-11 2016-02-19 OPUS4-12006 Vortrag Hinrichsen, G. The Fiber/Matrix Interphase: New Insights into an old Problem 1998 INTERNATIONAL CONFERENCES ON POLYMER CHARACTERIZATION POLYCHAR-6 INTERNATIONAL CONFERENCES ON POLYMER CHARACTERIZATION POLYCHAR-6 Denton, TX, USA 1998-01-07 1998-01-09 2016-02-19 OPUS4-5940 Vortrag Hampe, Andreas The Single Fibre Pull-Out Test Performed with a Microcomposite Sample 1998 The Seventh International Conference on Composite Interfaces - ICCI-VII The Seventh International Conference on Composite Interfaces - ICCI-VII Fujisawa, Kanagawa, Japan 1998-05-10 1998-05-13 2016-02-19 OPUS4-12084 Vortrag Schulz, Eckhard Effect of Transcrystallization in Carbon Fibre Reinforced Poly(p-phenylene sulfide) Composites on the Interfacial Shear Strength Investigated with the Single Fibre Pull-out Test 1995 Europhysics Conference on Macromolecular Physics Europhysics Conference on Macromolecular Physics Prague, Czech Republic 1995-07-17 1995-07-20 2016-02-19 OPUS4-12003 Zeitschriftenartikel Hinrichs, V.; Leistner, A.; Kalinka, Gerhard; Schulz, Eckhard; Hinrichsen, G. Viscoelastic properties of the interphase in fibre reinforced polymers - measurement and simulation New York, NY North-Holland International Conference on Composite Interfaces 1999 Composite interfaces : proceedings 6 2 93 101 2016-02-19 OPUS4-13239 Vortrag Marotzke, Christian Microscopical failure processes in fiber reinforced polymers - Mechanical aspects of the adhesion between fiber and matrix 2006 11th International Conference on Mechanics and Technology of Composite Materials 11th International Conference on Mechanics and Technology of Composite Materials Sofia, Bulgaria 2006-10-02 2006-10-04 2016-02-19 OPUS4-12106 Posterpräsentation Kalinka, Gerhard Testing the fibre-matrix adhesion in fiber reinforced polymers using the single fibre push-out method 1999 8th European Conference on Applications of Surface and Interface Analysis (ECASIA 99) 8th European Conference on Applications of Surface and Interface Analysis (ECASIA 99) Seville, Spain 1999-10-04 1999-10-08 2016-02-19 OPUS4-12091 Vortrag Habel, Wolfgang Evaluation of the Adhesion Behaviour of Optical Fibers for Sensors Embedded in Cementitiuos Materials 1998 International Workshop on Fiber Optic Sensors for Construction Materials and Bridges International Workshop on Fiber Optic Sensors for Construction Materials and Bridges Newark, NJ, USA 1998-05-03 1998-05-05 2016-02-19 OPUS4-18258 Zeitschriftenartikel Juntaro, J.; Pommet, M.; Kalinka, Gerhard; Mantalaris, A.; Shaffer, M.S.P.; Bismarck, A. Creating Hierarchical Structures in Renewable Composites by Attaching Bacterial Cellulose onto Sisal Fibers Weinheim Wiley-VCH Verl. 2008 Advanced materials 20 16 3122 3126 10.1002/adma.200703176 2016-02-19 OPUS4-6451 Vortrag Schulz, Eckhard Investigation on mechanical behaviour of heterogeneous polymeric systems and fibre reinforced composites using micro indentation and scanning force microscopy 1998 18th Disc. Conf. and 56th PMM 18th Disc. Conf. and 56th PMM Prague, Czech Republic 1998-07-20 1998-07-23 2016-02-19 OPUS4-12105 Posterpräsentation Kalinka, Gerhard Influence of water on the fibre-matrix adhesion investigated by the single fiber indentation method 1998 4th European Conference on Adhesion, 1st World Congress on Adhesion an Related Phenomena 4th European Conference on Adhesion, 1st World Congress on Adhesion an Related Phenomena Garmisch-Partenkirchen, Germany 1998-09-06 1998-09-11 2016-02-19 OPUS4-5928 Vortrag Hampe, Andreas Comparison of the Interfacial Toughness Measured by the Single Fibre Pull-Out, the Indentation and the Fragmentation Test 1997 NIST, Workshop on Micro-Mechanics Measurement Technologies for Fiber-Polymer Interfaces NIST, Workshop on Micro-Mechanics Measurement Technologies for Fiber-Polymer Interfaces Gaithersburg, MD, USA 1997-05-28 1997-05-30 2016-02-19 OPUS4-12213 Vortrag Kalinka, Gerhard Comparison of Interfacial Properties obtained by using Single Filament Embedded Tensile Test and Push-in Test 1997 Recent Advancement of Interfacial Materials Science on Composite Materials '97 Recent Advancement of Interfacial Materials Science on Composite Materials '97 Kyoto, Japan 1997-05-07 1997-05-09 2016-02-19 OPUS4-6439 Vortrag Schulz, Eckhard Investigation of polymeric composites reinforced with high oriented short glass fibres using the single fibre push-out test 1997 Euro-Conf. Surfaces and Interfaces in Polymers and Composites Euro-Conf. Surfaces and Interfaces in Polymers and Composites Lausanne, Switzerland 1997-06-03 1997-06-06 2016-02-19 OPUS4-12092 Vortrag Schulz, Eckhard Investigations of the mechanical behaviour of heterogeneous polymeric systems and fibre reinforced composites using micro indentation and scanning force microscopy 1998 Special Lectures, 18. Disc. Conf. And 56the PMM.: Mech. Behaviour of polymeric materials Special Lectures, 18. Disc. Conf. And 56the PMM.: Mech. Behaviour of polymeric materials Prague, Czech Republic 1998-07-20 1998-07-23 2016-02-19 OPUS4-10894 Beitrag zu einem Sammelband Munz, Martin; Chung, Jae Un; Kalinka, Gerhard Possart, W. Mapping Epoxy Interphases Weinheim Wiley-VCH DECHEMA, Gesellschaft für Chemische Technik und Biotechnologie 2005 Adhesion : current research and applications 7 3-527-31263-3 7th European Conference on Adhesion ; 7th EURADH Freiberg, Germany 2004-09-01 103 123 2016-02-19 OPUS4-14027 Beitrag zu einem Tagungsband Marotzke, Christian; Kalinka, Gerhard Zachariev, G. Microscopical Failure Processes in Fiber Reinforced Polymers - Mechanical Aspects of the Adhesion between Fiber and Matrix Sofia Bulgarian Academy of Sciences 2006 Proceedings of the 11th International Conference on Mechanics and Technology of Composite Materials 11th International Conference on Mechanics and Technology of Composite Materials Sofia, Bulgaria 2006-10-02 2006-10-04 37 42 2016-02-19 OPUS4-48026 Vortrag Rabe, Torsten Deformation behavior of alumina and zirconia springs at room temperature At high temperatures and in harsh environments ceramic springs are often superior to metallic springs and allow for innovative solutions. A recently proposed application involves ceramic springs with metallized surfaces as capacitive force sensor. A strictly linear stress-strain characteristic of the spring is a precondition for such a sensor. Helical ceramic springs with rectangular cross-section have been produced from sintered hollow cylinders. Alumina, ATZ, Y-TZP, and Ce-TZP springs with identical dimensions were characterized and compared regarding deformation behavior. Spring deformation was investigated under various load scenarios. Dynamic compression was performed with deformation speeds from 0.3 to 30 mm/min. Spring constants of alumina springs are strain rate independent. By contrast, Y-TZP spring constant increases by approximately 3 % within the experimental framework. A high-precision test facility was developed to characterize spring displacement in nm range under static tensile load over long periods of time. Spring elongation with asymptotic course was observed for zirconia containing materials at room temperature. This effect is particularly strong in the case of Y-TZP. Up to 0.3 % time-dependent elongation was measured after 24 h under constant load. Deformation is completely reversible after unloading. Alumina springs do not show any time-dependent deformation under identical test conditions. Contrary to alumina springs, a non-linear stress-strain behavior of TZP springs at room temperature was proved in both test series. It is supposed, that pseudo-elasticity caused by stress-induced phase transformation from tetragonal to monoclinic is responsible for this special behavior of TZP springs. 2019 D-A-CH Keramiktagung Leoben, Austria 06.05.2019 09.05.2019 2019-05-22 OPUS4-7137 Vortrag Munz, Martin On the stiffness gradient at the interface between an amine-cured epoxy and a thermoplast 2005 6. Workshop 'Rasterkraftmikroskopie in der Werkstoffwissenschaft' an der Uni Erlangen, Inst. für Werkstoffwissenschaften veranstaltet vom Arbeitskreis 'Rastersondenmikroskopie in der Werkstoffwissenschaft' im Fachausschuss Metallographie der Deutschen Gesellschaft für Materialkunde (DGM) 6. Workshop 'Rasterkraftmikroskopie in der Werkstoffwissenschaft' an der Uni Erlangen, Inst. für Werkstoffwissenschaften veranstaltet vom Arbeitskreis 'Rastersondenmikroskopie in der Werkstoffwissenschaft' im Fachausschuss Metallographie der Deutschen Gesellschaft für Materialkunde (DGM) Erlangen, Germany 2005-02-17 2005-02-18 2016-02-19 OPUS4-50844 Zeitschriftenartikel Lüders, C.; Kalinka, Gerhard; Li, Wei; Sinapius, M.; Wille, T. Experimental and numerical multiscale approach to thermally cycled FRP Due to the different thermal expansion of the constituent materials, cyclic thermal loading of FRP induces alternating stresses in the material at two scales: at the micro scale (level of fibre-matrix-interaction) and at the macro scale (level of the multidirectional laminate). Especially the micro scale effect is not comprehensively investigated yet. Additionally, computational investigations mostly neglect this effect due to the homogenous modelling of the composite material. As this effect is assumed to significantly contribute to the fatigue of FRP at thermal loads, the present paper suggests an experimental and numerical multiscale approach including Experiments at the different involved material scales to separately observe the effects acting at these scales. The approach also includes numerical modelling for each scale to complement the knowledge gained from the Experiments and to create a basis for the consideration of the micro effect even in macroscopic fatigue models treating homogeneous modelled composites. The main focus of the contribution is to bring the overall Approach up for discussion, rather than to present the multiscale modelling details. Niederlande Elsevier Ltd. 2020 Composite Structures 244 112303 10.1016/j.compstruct.2020.112303 2020-06-08 OPUS4-21295 Beitrag zu einem Tagungsband Marotzke, Christian; Kalinka, Gerhard Local failure processes in fiber reinforced polymers The breakage of a fiber and its effect on the strain energy is studied in a model composite, this is, a single fiber embedded in a dogbone specimen. The fracture process is recorded by an acoustic emission device, the crack patterns are monitored under a microscope. A finite element analysis is performed in order to estimate the energy released by different failure scenarios. The abilities and limitations of the acoustic emission analysis in characterizing different failure types in fiber reinforced composites are evaluated. Edinburgh, UK The British Composites Society 2009 ICCM17 - 17th International conference on composite materials (Proceedings) ICCM17 - 17th International conference on composite materials Edinburgh, UK 2009-07-27 2009-07-31 D7:8 1 10 2016-02-19 OPUS4-11983 Zeitschriftenartikel Hinrichs, V.; Kalinka, Gerhard; Hinrichsen, G. An Avrami-based model for the description of the secondary crystallization of polymers A mathematical model for the description of the overall crystallization of polymers has been developed which separates the pure geometric spreading of the semicrystalline superstructures from the increasing crystallinity inside these entities. The model uses the Avrami theory for the geometric part and a freely optional function for the increasing local crystallinity. The two functions are combined by a mathematical procedure called convolution. The free option of the local crystallinity function enables this model to permit calculation of this function, which is not accessible to direct measurement. Thus with given Avrami parameters and measured values of the time-dependent overall crystallinity, this function of the local crystallinity (secondary crystallization function) can be calculated. The model has been applied to test data produced by computer simulations. New York, NY Dekker Chemistry 1996 Journal of macromolecular science B 35 3-4 295 302 10.1080/00222349608220382 2016-02-19 OPUS4-11987 Zeitschriftenartikel Schulz, Eckhard; Kalinka, Gerhard; Auersch, W. Effect of Transcrystallization in Carbon Fiber Reinforced Poly(p/phenylene sulfide) Composites on the Interfacial Shear Strength Investigated with the Single Fiber Pull-Out Test The effect of transcrystallinity in carbon fiber reinforced poly(p-phenylene sulfide (PPS) composites on the apparent shear strength was investigated with the single fiber pull-out test. Transcrystalline zones around the reinforcing fibers do not seem to improve the adhesion level significantly. Neighbor fibers hinder the formation of the transcrystalline zone and a ductile fracture behavior can be observed. However, the apparent strength level is slightly higher for composites containing such reinforcing neighbor fibers compared with single fiber composite samples. During annealing a brittle interface can be formed in the multifiber composite yielding a higher level of the apparent shear strength. New York, NY Dekker Chemistry 1996 Journal of macromolecular science B 35 3-4 527 546 10.1080/00222349608220393 2016-02-19 OPUS4-11995 Zeitschriftenartikel Nowak, H.; Kalinka, Gerhard; Hinrichsen, G. Investigations on the cold crystallization of pure and filled PETP by dielectric measurements The cold crystallization of pure and filled poly(ethylene terephthalate) (PETP) after quenching from the melt has been investigated by dielectric measurements in two different modes: The first one using constant heating-rate (in the temperature range from 320 to 480 K) and the second one under isothermal conditions (at 378 K). The complex dielectric constant (ε´, tan δ) is influenced by crystallization. Two α-relaxation regions are identified: The αa-relaxation region from the pure amorphous phase and the α´-relaxation region from the spherulitic phase. The investigations on the filled systems (PETP + 10% aramid puple, PETP + 30% short glass fibres) prove that an influence of the fillers on the time delay and rate of crystallization and on the geometry of the growing spherulites exists. Weinheim Wiley-VCH Verl. 1993 Acta polymerica 44 1 25 28 2016-02-19 OPUS4-12012 Zeitschriftenartikel Thomason, J.L.; Kalinka, Gerhard A technique for the measurement of reinforcement fibre tensile strength at sub-millimetre gauge lengths The strength of composite reinforcement fibres is normally measured on samples of much greater length than the actual residual fibre lengths found in many composite materials. This is due to a number of limitations of the standard techniques which are employed. We present a description of a technique which enables values for the tensile strength of composite reinforcement fibres at short gauge lengths to be obtained. The technique is based on an adaptation of a micro-mechanical test apparatus for fibre pullout measurements. Data is presented which was obtained at gauge lengths of 180–380 µm on E-glass and S-2 glass® fibres taken from different chopped reinforcement products. The technique can be used at gauge lengths as short as 20 µm. The data indicates that the values of average fibre strength in these products are significantly below the pristine glass strength values. Oxford Elsevier 2001 Composites / A 32 1 85 90 10.1016/S1359-835X(00)00122-6 2016-02-19 OPUS4-28694 Beitrag zu einem Tagungsband Bismarck, A.; Carreyette, S.; Fontana, Q.P.V.; Greenhalgh, E.S.; Jacobsson, P.; Johansson, P.; Marczewski, M.J.; Kalinka, Gerhard; Kucernak, A.; Shaffer, M.S.; Shirshova, N.; Steinke, J.H.G.; Wienrich, Malte Multifunctional epoxy resin for structural supercapacitors Polymer-based electrolytes based on commercially available epoxy resins were prepared through the addition of a liquid electrolyte, a solution of a lithium salt in an ionic liquid. The polymer monoliths were characterized using impedance spectroscopy, 3-point bending test, scanning electron microscopy (SEM) and nitrogen adsorption (BET). The balance of ionic conductivity and flexural modulus is crucially dependent on the relative proportions of epoxy resin to electrolyte. Also the effect of the liquid electrolyte on curing kinetics and processing was assessed by complex viscosity measurements and differential scanning calorimetry (DSC). Only one out of the three resins investigated exhibited a significant acceleration effect. University of Padova 2012 ECCM15 - 15th European conference on composite materials (Proceedings) 978-88-88785-33-2 ECCM15 - 15th European conference on composite materials Venice, Italy 2012-06-24 2012-06-28 1 8(?) 2016-02-20 OPUS4-35533 Vortrag Elabshihy, Karim Investigation of the time-dependent behavior of cnt-filled epoxy using nanoindentation Epoxy/Carbon nanotube (CNT) composites are interesting materials that could be used in a wide variety of applications. In this study, CNT contents of 0.25, 0.5, 1 and 2 wt% were used for reinforcing epoxy. A nanoindentation device and a temperature regulating system were developed in order to investigate the effect of CNTs on the time-dependent properties of epoxy using relaxations and creep tests on the nano scale. The relaxation tests showed a significant shift for the relaxation spectrum towards shorter times with introducing a low CNT content of 0.25 wt%. Additionally, creep tests showed that both the holding time at a constant load and the unloading velocity have a major effect on the contact stiffness. However, there was no effect for the CNTs on the creep behavior with contents lower than 1 wt%, which was related to the presence of a percolation threshold around this value. 2013 Nanobrücken 2013 Dresden, Germany 20.03.2013 22.03.2013 2016-03-21 OPUS4-15814 Zeitschriftenartikel Ho, K.K.C.; Kalinka, Gerhard; Tran, M.Q.; Polyakova, N.V.; Bismarck, A. Fluorinated carbon fibres and their suitability as reinforcement for fluoropolymers The interaction between direct fluorinated carbon fibres and various fluoropolymers (ethylene-chlorotrifluoroethylene, poly vinylidene fluoride, fluorinated ethylene propylene copolymer and tetrafluoroethylene-perfluoro alkoxy vinyl ether copolymer) was studied by means of direct wetting measurements between fibres and the polymer melts and single fibre pull-out tests. The results of both techniques allow the adhesion behaviour between the fibres and the matrices to be predicted. The results obtained show that a low degree of surface fluorination of carbon fibres leads to an improved wettability between the fibres and fluoropolymer melts and this is an indicator for an improved thermodynamic work of adhesion. The apparent interfacial shear strength as measure of practical adhesion, determined by the single fibre pull-out test, increases with increasing degree of surface fluorine content up to a maximum, which depends on the degree of fluorination of the matrix used. The improved interaction between the fibre and the matrix is due to an enhanced compatibility at the fibre/matrix interface. Barking Elsevier 2007 Composites science and technology 67 13 2699 2706 10.1016/j.compscitech.2007.02.012 2016-02-19 OPUS4-23162 Zeitschriftenartikel Pommet, M.; Juntaro, J.; Heng, J.Y.Y.; Mantalaris, A.; Lee, A.F.; Wilson, K.; Kalinka, Gerhard; Shaffer, M.S.P.; Bismarck, A. Surface modification of natural fibers using bacteria: depositing bacterial cellulose onto natural fibers to create hierarchical fiber reinforced nanocomposites Triggered biodegradable composites made entirely from renewable resources are urgently sought after to improve material recyclability or be able to divert materials from waste streams. Many biobased polymers and natural fibers usually display poor interfacial adhesion when combined in a composite material. Here we propose a way to modify the surfaces of natural fibers by utilizing bacteria (Acetobacter xylinum) to deposit nanosized bacterial cellulose around natural fibers, which enhances their adhesion to renewable polymers. This paper describes the process of modifying large quantities of natural fibers with bacterial cellulose through their use as substrates for bacteria during fermentation. The modified fibers were characterized by scanning electron microscopy, single fiber tensile tests, X-ray photoelectron spectroscopy, and inverse gas chromatography to determine their surface and mechanical properties. The practical adhesion between the modified fibers and the renewable polymers cellulose acetate butyrate and poly(l-lactic acid) was quantified using the single fiber pullout test. Washington, DC, USA ACS Publ. American Chemical Society 2008 Biomacromolecules 9 6 1643 1651 10.1021/bm800169g 2016-02-19 OPUS4-28695 Beitrag zu einem Tagungsband Wienrich, Malte; Kalinka, Gerhard; Greenhalgh, E.S.; Carreyette, S.; Bistritz, Martina; Shirshova, N.; Houllé, M.; Asp, L. E.; Bismarck, A.; Fontana, Q.P.V. Impact of ionic liquid on the mechanical performance of matrix polymer for fibre reinforced materials for energy storage For the concept of using structural materials such as carbon fibre reinforced plastics as energy storage devices, new matrix polymers are required. These polymers must provide ionic conductivity as well as adequate mechanical strength. In the EU-Project StorAGE this requirements are fulfilled by adding ionic liquid to commercial polymers. The mechanical properties of these mixtures materials were characterized by using a 3-point-bending device. In addition, single fibre pull test were performed in order to get information on the interfacial shear strength. Adding of ionic liquid has an impact on the mechanical performance of the materials. A decrease of the flexural strength and modulus of less than 10% of the value of the reference materials took part. The interfacial shear strength decreased to a value of around one third compare to the reference material. University of Padova 2012 ECCM15 - 15th European conference on composite materials (Proceedings) 978-88-88785-33-2 ECCM15 - 15th European conference on composite materials Venice, Italy 2012-06-24 2012-06-28 1 4(?) 2016-02-20 OPUS4-16026 Zeitschriftenartikel Ho, K.K.C.; Lamoriniere, S.; Kalinka, Gerhard; Schulz, Eckhard; Bismarck, A. Interfacial behavior between atmospheric-plasma-fluorinated carbon fibers and poly(vinylidene fluoride) Atmospheric-plasma fluorination was used to introduce fluorine functionalities onto the surface of carbon fibers without affecting their bulk properties. The interfacial adhesion between atmospheric-plasma-fluorinated carbon fibers and poly(vinylidene fluoride) (PVDF) was studied by means of direct wetting measurements and single fiber pullout tests. Measured contact angles of PVDF melt droplets on modified carbon fibers show that short exposure times of carbon fibers to atmospheric-plasma fluorination (corresponding to a degree of surface fluorination of F/C = 0.01 (1.1%)) leads to improved wettability of the fibers by PVDF melts. The apparent interfacial shear strength as a measure of practical adhesion, determined by the single-fiber pullout test, increases by 65% under optimal treatment conditions. The improved practical adhesion is not due to the formation of transcrystalline regions around the fibers or a change of the bulk matrix crystallinity or to an increased surface roughness; it seems to be due to the compatibilization of the interface caused of the atmospheric-plasma fluorination of the carbon fibers. Orlando, Fla. Elsevier 2007 Journal of colloid and interface science 313 2 476 484 10.1016/j.jcis.2007.04.076 2016-02-19 OPUS4-22171 Zeitschriftenartikel Godara, A.; Gorbatikh, L.; Kalinka, Gerhard; Warrier, A.; Rochez, O.; Mezzo, L.; Luizi, F.; van Vuure, A.W.; Lomov, S.V.; Verpoest, I. Interfacial shear strength of a glass fiber/epoxy bonding in composites modified with carbon nanotubes In recent years, carbon nanotubes (CNTs) grown on fibers have attracted a lot of interest as an additional reinforcing component in conventional fiber-reinforced composites to improve the properties of the fiber/matrix interface. Due to harsh growth conditions, the CNT-grafted fibers often exhibit degraded tensile properties. In the current study we explore an alternative approach to deliver CNTs to the fiber surface by dispersing CNTs in the fiber sizing formulation. This route takes advantage of the developed techniques for CNT dispersion in resins and introduces no damage to the fibers. We focus on unidirectional glass fiber/epoxy macro-composites where CNTs are introduced in three ways: (1) in the fiber sizing, (2) in the matrix and (3) in the fiber sizing and matrix simultaneously. Interfacial shear strength (IFSS) is investigated using single-fiber push-out microindentation. The results of the test reveal an increase of IFSS in all three cases. The maximum gain (over 90%) is achieved in the composite where CNTs are introduced solely in the fiber sizing. Barking Elsevier 2010 Composites science and technology 70 9 1346 1352 10.1016/j.compscitech.2010.04.010 2016-02-19 OPUS4-34568 Zeitschriftenartikel Qian, Hui; Bismarck, A.; Greenhalgh, E.S.; Kalinka, Gerhard; Shaffer, M.S.P. Hierarchical composites reinforced with carbon nanotube grafted fibers: The potential assessed at the single fiber level The feasibility of reinforcing conventional carbon fiber composites by grafting carbon nanotubes (CNTs) onto the fiber surface has been investigated. Carbon nanotubes were grown on carbon fibers using the chemical vapor deposition (CVD) method. Iron was selected as the catalyst and predeposited using the incipient wetness technique before the growth reaction. The morphology of the products was characterized using scanning electron microscopy (SEM), which showed evidence of a uniform coating of CNTs on the fiber surface. Contact angle measurements on individual fibers, before and after the CNT growth, demonstrated a change in wettability that can be linked to a change of the polarity of the modified surface. Model composites based on CNT-grafted carbon fibers/epoxy were fabricated in order to examine apparent interfacial shear strength (IFSS). A dramatic improvement in IFSS over carbon fiber/epoxy composites was observed in the single fiber pull-out tests, but no significant change was shown in the push-out tests. The different IFSS results were provisionally attributed to a change of failure mechanism between the two types of tests, supported by fractographic analysis. Washington, DC American Chemical Society 2008 Chemistry of materials 20 5 1862 1869 10.1021/cm702782j 2016-02-20 OPUS4-18259 Zeitschriftenartikel Tran, M.Q.; Ho, K.K.C.; Kalinka, Gerhard; Shaffer, M.S.P.; Bismarck, A. Carbon fibre reinforced poly(vinylidene fluoride): Impact of matrix modification on fibre/polymer adhesion The quality of interfacial interaction is dictated by the surface chemistry of the carbon fibres and the composition of the matrix. The composition of poly(vinylidene fluoride) (PVDF) was modified by the addition of maleic anhydride grafted PVDF. The surface properties of the various matrix formulations were characterised by contact angle and electrokinetic measurements. Carbon fibres were modified by industrial electrochemical oxidation and oxidation in nitric acid, or the use of a traditional epoxy-sizing of industrially oxidised fibres. The surface composition, morphology and wetting behaviour of the carbon fibres was characterised. The interaction between modified PVDF and the carbon fibres was studied by direct contact angle measurements between PVDF melt on single carbon fibres and by single fibre pull-out tests. The best wetting and adhesion behaviour was achieved between PVDF containing 5 ppm grafted maleic anhydride (MAH) and epoxy-sized carbon fibres. The addition of MAH-grafted PVDF to the unmodified PVDF caused the apparent interfacial shear strength to increase by 184%. The apparent interfacial shear strength of this fibre–matrix combination allowed for the utilisation of 100% of the yield tensile strength of PVDF. Barking Elsevier 2008 Composites science and technology 68 7-8 1766 1776 10.1016/j.compscitech.2008.02.021 2016-02-19 OPUS4-34564 Zeitschriftenartikel Wettmarshausen, Sascha; Friedrich, Jörg Florian; Meyer-Plath, Asmus; Kalinka, Gerhard; Hidde, Gundula; Weidner, Steffen Coating of carbon fibers with adhesion-promoting thin poly(acrylic acid) and poly(hydroxyethylmethacrylate) layers using electrospray ionization Thin coatings of poly(acrylic acid) (PAA) and poly(hydroxyethylmethacrylate) (PHEMA) were deposited onto carbon fibers by means of the electrospray ionization (ESI) technique in ambient air. These high-molecular weight polymer layers were used as adhesion promoters in carbon fiber–epoxy resin composites. Within the ESI process, the carbon fibers were completely enwrapped with polymer in the upper 10 plies of a carbon fiber roving. As identified with scanning electron microscopy also shadowed fibers in a bundle as well as backsides of fiber rovings were pinhole-free coated with polymers (‘electrophoretic effect'). Under the conditions used, the layers have a granular structure. Residual solvent was absent in the deposit. PAA and PHEMA films did not show any changes in composition and structure in comparison with the original polymers as analyzed by X-ray photo-electron spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Single-fiber pullout tests of coated fibers embedded in epoxy resin showed significantly increased interfacial shear strength. It is assumed that chemical bonds between carbon fiber poly(acrylic acid) and epoxy resin contribute significantly to the improved interactions. Utrecht VNU Science Press 2015 Journal of adhesion science and technology 29 15 1628 1650 10.1080/01694243.2015.1040980 2016-02-20 OPUS4-12011 Zeitschriftenartikel Kalinka, Gerhard; Leistner, André; Hampe, Andreas Characterisation of the fibre/matrix interface in reinforced polymers by the push-in technique The push-in test is the only micromechanical test method that is not restricted to artificial fibre/matrix arrangements, but allows the in situ characterisation of interfaces in composites fabricated and stressed under realistic conditions. However, with the application of this method to reinforced polymers some problems arise both in the mathematical model for evaluating test data and in the practical performance of the test. Because in some cases the deformation of the relatively compliant polymeric matrices cannot be neglected, an extension of the existing model is required. For this purpose, the elastic energy of the material around the debonded part of the fibre is estimated and included in the energy-balance analysis. Because of the small diameter of the fibres usually used for reinforcing polymers, a test apparatus was designed which ensures a high positioning accuracy in the xy plane as well as in the z direction. In order to minimise thermal and mechanical influences, the microscope for fibre selection and the force sensor/indenter are directly connected together and the apparatus is designed to be stiff in all components. A solid-state bending joint guarantees very precise control of the axial movement. Three examples of the application of this easy-to-handle and low-cost test apparatus are presented briefly in the paper: assess fibre/matrix combinations, measures to improve the interfacial adhesion and the influence of water on the interface. Barking Elsevier 1997 Composites science and technology 57 8 845 851 2016-02-19 OPUS4-44728 Vortrag Rabe, Torsten Helical zirconia (TZP) springs manufacturing and testing under mechanical and thermal load Helical springs with a rectangular cross-section have been machined from sintered and grinded hollow cylinders with high geometrical precision and good reproducibility. Such springs made from tetragonal zirconia polycrystal (TZP) ceramic show excellent edge quality because of high fracture toughness and bending strength of the starting material. Hence, springs with desired geometric dimension and tailored spring constant can be manufactured for highly demanding applications at high temperatures and in harsh environments. Prior to any practical use, application limits of springs under mechanical and thermal load have to be analyzed. Therefore, different displacement experiments were carried out on the helical TZP springs. - Dynamic displacement tests at various temperatures from -15°C to +60°C using a piezo actor to load/unload springs with frequencies between 1 and 40 Hz: Springs remained undamaged and the spring constants were not altered, even after more than one million cycles of compression loading. - Long-time displacement measurements under static tensile loading at room temperature with a high-precision interferometer test facility: Significant spring elongation under constant strain was surprisingly proved over a period of many hours already at room temperature. - Creeping experiments for 48 h under static compression load at different temperatures up to 1000 °C: After cooling down and load removing no permanent length reduction of springs was observed for test temperatures up to 700 °C. However, reshaping of TZP springs by plastic deformation is possible at higher temperatures and opens up additional possibilities for spring design and manufacturing. 2018 German Ceramic Society, Annual Meeting 2018 München, Germany 09.04.2018 12.04.2018 2018-04-20 OPUS4-52184 Zeitschriftenartikel Plichta, T.; Sirjovona, V.; Zvonek, M.; Kalinka, Gerhard; Cech, V. The Adhesion of Plasma Nanocoatings Controls the Shear Properties of GF/Polyester Composite High-performance fibre-reinforced polymer composites are important construction materials based not only on the specific properties of the reinforcing fibres and the flexible polymer Matrix but also on the compatible properties of the composite interphase. First, oxygen-free (a-CSi:H) and oxygen-binding (a-CSiO:H) plasma nanocoatings of different mechanical and tribological properties were deposited on planar silicon dioxide substrates that closely mimic E-glass. The nanoscratch test was used to characterize the nanocoating adhesion expressed in terms of critical normal load and work of adhesion. Next, the same nanocoatings were deposited on E-glass fibres, which were used as reinforcements in the polyester composite to affect its interphase properties. The shear properties of the polymer composite were characterized by macro- and micromechanical tests, namely a short beam shear test to determine the short-beam strength and a single fibre push-out test to determine the interfacial shear strength. The results of the polymer composites showed a strong correlation between the short-beam strength and the interfacial shear strength, proving that both tests are sensitive to changes in fibre-matrix adhesion due to different surface modifications of glass fibres (GF). Finally, a strong correlation between the shear properties of the GF/polyester composite and the adhesion of the plasma nanocoating expressed through the work of adhesion was demonstrated. Thus, increasing the work of adhesion of plasma nanocoatings from 0.8 to 1.5 mJ·m−2 increased the short-beam strength from 23.1 to 45.2 MPa. The results confirmed that the work of adhesion is a more suitable parameter in characterising the level of nanocoating adhesion in comparison with the critical normal load. Basel,Schweiz MDPI 2021 Polymers 13 4 593 urn:nbn:de:kobv:b43-521844 10.3390/polym13040593 https://creativecommons.org/licenses/by/4.0/deed.de 2021-03-01 OPUS4-42511 Posterpräsentation Barnefske, Lena Self-healing silicone rubber for F-POF partial discharge sensors in HV cable accessories To avoid a catastrophic failure of insulation in high-voltage (HV) applications, a monitoring of partial discharges (PD) is necessary. Fluorescently labelled polymer optical fibres (F-POF) offer an electrically passive method for PD detection in HV facilities. F-POF could be embedded into HV cable insulation material, which are usually made of silicone rubber. Due to the difficult accessibility of HV cable accessories, a self-healing silicone rubber, based on incorporated capsules, with prolonged service life after PD detection represents an attractive material design for HV electrical insulation. 2017 26th International Conference on Plastic Optical Fibres Aveiro, Portugal 13.09.2017 15.09.2017 2017-10-13 OPUS4-52711 Zeitschriftenartikel Gebhardt, M.; Manolakis, I.; Chatterjee, A.; Kalinka, Gerhard; Deubener, J.; Pfnür, H.; Chakraborty, S.; Meiners, D. Reducing the raw material usage for room temperature infusible and polymerisable thermoplastic CFRPs through reuse of recycled waste matrix material In this work, a closed loop recycling process is investigated, which allows polymerised bulk thermoplastic matrix (Elium 150) from production waste (also referred to as recyclate) to be reused as additive in composite manufacturing by vacuum assisted resin infusion (VARI) of virgin Elium 150 monomer. It is shown that this process can save up to 7.5 wt% of virgin material usage in each processing cycle. At the same time, the thermal stability and stiffness of the composite increases with the proportion of recyclate introduced. Contemporarily, the shear and bending properties have also been observed to improve. Gel permeation chromatography (GPC) showed that the changes observed are due to an increase in molecular weight with the recyclate content. In particular, a correlation between the molecular weight and the shear properties of the composite was discovered using single fibre push-out tests. Niederlande Elsevier Ltd. 2021 Composites Part B: Engineering 216 108877 10.1016/j.compositesb.2021.108877 2021-06-03 OPUS4-56379 Zeitschriftenartikel Guerra, E. S. S.; Silva, B. L.; Melo, J. D. D.; Kalinka, Gerhard; Barbosa, A. P. C. Microscale evaluation of epoxy matrix composites containing thermoplastic healing agent Among the strategies to produce healable thermosetting systems is their modification by the addition of thermoplastic particles. This work investigates the influence of poly(ethylene-co-methacrylic acid) (EMAA) on fibermatrix interfacial properties of a glass fiber reinforced epoxy matrix composite. Epoxy-EMAA interactions were evaluated using differential scanning calorimetry (DSC) and infrared spectroscopy. The effects of EMAA on the epoxy network formation were evidenced by changes in glass transition temperature, cure kinetics and alteration of chemical groups during cure. Interfacial shear strength (IFSS) measurements obtained by single fiber pull-out tests indicate similar interfacial properties for pure and EMAA modified epoxy. Additionally, the potential for self-healing ability of an EMAA modified epoxy was demonstrated. However, IFSS after a healing cycle for the EMAA modified epoxy was lower as compared to the pure epoxy, because of the lower fiber-EMAA interfacial shear strength. So, thermoplastic healing agents has not only to fill cracks in the matrix material, but also have to be optimized regarding its interface properties to the reinforcing fibers. Niederlande Elsevier Ltd. 2022 Composites Science and Technology 232 1 9 10.1016/j.compscitech.2022.109843 2022-11-24 OPUS4-35496 Vortrag Elabshihy, Karim Nano-mechanical characterization of epoxy/Cu interphase Characterization of the mechanical properties of interphases is essential when designing multicomponent materials such as fiber-reinforced matrices, protective coatings or multi-layered structures for integrated circuits. It can provide vital information about the durability of the finished product as a composite because failure is often initiated in the interfacial region induced by internal or external stress during fabrication or service. Nanoindentation is a powerful tool for investigating mechanical properties on the micro/nano scale. However, there are some challenges associated with conducting nanoindentation near interface regions. One main challenge is that the small thickness of the interphase region (typically 1-2µm) makes it difficult to apply several adjacent indents without overlap. Another issue is that the indentations are usually restricted by local reinforcement, and it becomes difficult to isolate the change in mechanical properties due solely to interphase formation. In this study we try to gauge the feasibility of nanoindentation for characterizing epoxy/Cu interphases. We develop a sample preparation method and optimize nanoindentation parameters in an attempt to avoid the restrictions mentioned above. Atomic force microscopy (AFM) and finite element analysis are employed as reference techniques to evaluate the effectiveness of our technique. We show the influence of preparation method and nanoindentaion parameters on measurements of interphase properties and how they relate the mentioned challenges. 2016 Nanobrücken 2016 Saarbrücken, Germany 02.03.2016 2016-03-10 OPUS4-29272 Beitrag zu einem Tagungsband Greenhalgh, E.S.; Ankersen, J.; Asp, L. E.; Bismarck, A.; Fontana, Q.P.V.; Houlle, M.; Kalinka, Gerhard; Kucernak, A.; Mistry, M.; Nguyen, S.; Qian, H.; Shaffer, M.S.P.; Shirshova, N.; Steinke, J.H.G.; Wienrich, Malte Mechanical and microstructural characterisation of multifunctional structural power composites Although the inherent anisotropy of polymer composites has presented daunting technical challenges, these materials now offer engineers considerable opportunities for efficient structural design. More recently, the advent of multifunctional composites which can fulfill more than one role within a system has attracted considerable interest, providing designers with exciting opportunities to innovate. Of particular interest here are structural power composites, which simultaneously carry mechanical load whilst storing/delivering electrical energy. Although the development of these composites is highly challenging, often with conflicting constituent requirements, the STORAGE consortium has had considerable success in the development of these materials for automotive applications. The focus of this paper is structural supercapacitors, the basic architecture of a single cell of which is shown in Fig. 1. This entails two carbon fibre woven lamina (electrodes) which sandwich a glass fibre woven lamina (separator), all of which is embedded within a multifunctional matrix (electrolyte). This architecture has been the focus of the research to date, leading to components such as that shown in Fig.1 having been fabricated. This paper reports on the mechanical properties and microstructures of the different reinforcement and matrix combinations for structural supercapacitors. Canadian Association for Composite Structures and Materials 2013 ICCM19 - 19th International conference on composite materials (Proceedings) ICCM19 - 19th International conference on composite materials Montreal, Canada 28.07.2013 02.08.2013 2228 2237 2016-02-20 OPUS4-53639 Zeitschriftenartikel Gebhardt, M.; Malolakis, I.; Kalinka, Gerhard; Deubener, J.; Chakraborty, S.; Meiners, D. Re-use potential of carbon fibre fabric recovered from infusible thermoplastic CFRPs in 2nd generation thermosetting-matrix composites The research presented here attempts to assess the potential for re-using carbon fibre (CF) fabrics recovered from recycling infusible acrylic thermoplastic carbon fibre reinforced polymer composites (CFRPs) in a universal manner, i.e. by combining with a wide variety of matrices to manufacture 2nd generation composite laminates by resin infusion. The 2nd generation composites have been compared in terms of bulk and interfacial properties against counteparts processed with virgin carbon fibre fabric infused with the same matrices. Generally, an increase in damping (tanδ) was observed in all 2nd generation composites, which can be attributed to a residual thin thermoplastic layer present on the recovered fibres. The interfacial adhesion of the 2nd generation Composites was investigated by shear tests and scanning electron micsoscopy, and also appears to be less influenced by the type of matrix. Niederlande Elsevier Ltd. 2021 Composites Communications 28 100974 10.1016/j.coco.2021.100974 2021-10-28 OPUS4-6848 Zeitschriftenartikel Sturm, Heinz; Schulz, Eckhard Local AC current contrast on carbon fiber surfaces imaged by scanning force microscopy After a delamination process in a C-fiber reinforced polymer composite, the identification of the polymer residue of poly-(phenylene sulphide) on carbon fiber surfaces gives important information on the composite failure mechanism. Using scanning force microscopy (SFM) in its lateral force imaging mode or with the stiffness imaging mode, it is almost impossible to distinguish the two composite components owing to a very low material-based contrast of the local friction and compliance. The new technique using contrast based on a local AC current measurement allows a clear identification of the conducting carbon fiber and the non-conducting polymer coverage. Weinheim, Germany Wiley-VCH Verl. 1995 Acta polymerica 46 5 379 384 10.1002/actp.1995.010460505 2016-02-19 OPUS4-39519 Vortrag Sturm, Heinz Improving polymer matrix additives for composite structures: a focus on boehmite The aims of the Research Unit „Acting Principles of Nano-Scaled Matrix Additives for Composite Structures" (DFG FOR 2021) are based on different synergetic pathways. Challenges are to achieve an improved damage tolerance combined with unchanged processability and a proof of the nano-based effect from molecular scale up to structural level. First of all, a comprehensive understanding of the acting mechanisms of nano-scaled ceramic additives onto polymer matrices of continuous fibre reinforced polymer composites with respect to improved matrix dominated properties is in focus. To proof of the nanoscopic and microscopic effects up to structural level; experimental investigations start on the functional correlation between the particle properties and the resulting properties of the epoxy as suspension and in the solid state. This includes tests for the resulting composite structures as well. Along the entire process chain different multi-scale simulations are performed from molecular modelling up to the macroscopic, structural level. The combination of experimental investigations and simulation methods enables a holistic understanding of the acting principles and basic mechanisms. Specialized techniques based on Scanning Force Microscopy are the basis of our analysis of physicochemical properties of the boehmite nanoparticles and their polymer environment. A surface map of mechanical properties as an input for simulations facilitate a deeper understanding of such composites across all scales. This enables us to understand the macroscopic structure-property relationship and to predict failure mechanisms as well as routes for optimization. 2017 92nd DKG annual meeting and symposium on high performance ceramics Berlin, Germany 19.03.2017 22.03.2017 2017-03-24 OPUS4-48501 Vortrag Schreier, Andy Distributed Brillouin sensing in polymer optical fibers A brief overview about the results obtained within the BAM PhD framwork. 2019 Meeting of the Terahertz-Photonics-Group at IHF, Technische Universität Braunschweig Braunschweig, Germany 17.07.2019 2019-07-18 OPUS4-27627 Zeitschriftenartikel Schukar, Vivien; Kusche, Nadine; Kalinka, Gerhard; Habel, Wolfgang Field deployable fiber bragg grating strain patch for long-term stable health monitoring applications A fiber Bragg grating (FBG) strain patch specially adapted for long-term and high-strain applications has been developed and characterized. The design concept for the patch is based on a glass-fiber reinforced plastic (gfrp) carrier material. The developed concept for the FBG integration into the carrier material was derived from reliable integration procedure of FBG sensors into composite structures. The patches' temperature sensitivity, strain gauge factor, fiber-matrix interface adhesion and fatigue behavior were characterized. As a result, FBG strain patches with linear temperature and strain behavior, as well as excellent fatigue resistance, were developed and can be used as part of a monitoring system for advanced composite materials in aerospace structures or wind turbine power plants. Basel MDPI 2013 Applied sciences 3 1 39 54 urn:nbn:de:kobv:b43-276271 10.3390/app3010039 http://creativecommons.org/licenses/by/3.0/de/deed.de 2016-02-20 OPUS4-39464 Vortrag Bertin, Annabelle Bioinspired hybrid organic-inorganic copolymers The demand for high-performance materials has strongly increased over the last decade. One way to improve their performance is to introduce material gradients as found in Nature (for example squid beaks, spider fangs, mussel byssal threads). One path towards the achievement of such material gradients is the synthesis of hybrid (gradient) copolymers, for instance based on silane and organic monomers. Since not all gradient copolymers can be synthesized by utilising the reactivity ratios of the monomers, forced gradients have to be used. However, in order to obtain gradient copolymers at high conversions, living or pseudo-living copolymerizations have to be performed and so far only few hybrid (organic / inorganic) gradient copolymers have been reported. In this contribution we will present the synthesis of a novel organic / inorganic hybrid copolymer via controlled radical polymerization. 2017 5th International Conference on Multifunctional, Hybrid and Nanomaterials Lisbon, Portugal 06.03.2017 10.03.2017 2017-03-23 OPUS4-29273 Beitrag zu einem Tagungsband Shirshova, N.; Bismarck, A.; Carreyette, S.; Greenhalgh, E.S.; Johansson, P.; Marczewski, M.J.; Jacobsson, P.; Kalinka, Gerhard; Shaffer, M.S.P.; Wienrich, Malte; Steinke, J.H.G. Correlations between mechanical properties and ionic conduction of structural electrolytes with bicontinuous morphologies Electrolyte systems that can carry mechanical load while allowing for high levels of ionic conductivity are an important prerequisite for structural power storage devices. Introduction of structural power storage into the variety of consumer products will allow saving in weight and volume. Moreover, using a supercapacitor/battery system in hybrid electric vehicles (HEV), the supercapacitor part will extend the battery lifetime by protecting it from the high peak currents. To successfully produce structural power storage requires the development of multifunctional electrolytes where one has to simultaneously maximize mechanical properties and ionic conductivity. Canadian Association for Composite Structures and Materials 2013 ICCM19 - 19th International conference on composite materials (Proceedings) ICCM19 - 19th International conference on composite materials Montreal, Canada 28.07.2013 02.08.2013 72 79 2016-02-20 OPUS4-46091 Zeitschriftenartikel Zhandarov, S.; Mäder, E.; Kalinka, Gerhard; Scheffler, C.; Poitzsch, C.; Fliescher, S. Investigation of interfacial strength parameters in polymer matrix composites: Compatibility and reproducibility Effects of various geometrical and physical factors, as well as the method of data reduction (analysis of experimental forceedisplacement curves) on the values of local interfacial strength parameters (local IFSS, td, and critical energy release rate, Gic) determined by means of a single fiber pull-out test are discussed. Experimental results of our pull-out tests on several fiberepolymer matrix systems showed that td and Gic weakly depended on geometrical factors. However, the pull-out test appeared to be sensitive to the conditions of specimen formation and testing, such as changing the nature of the contacting surfaces (fiber sizing) and the fiber pull-out rate. Of several methods of td and Gic Determination from a forceedisplacement curve, the most reliable and reproducible one is the approach based on the values of the maximum force recorded in a pull-out test and the interfacial frictional force immediately after fiber debonding. Amsterdam Elsevier 2018 Advanced Industrial and Engineering Polymer Research 1 1 82 92 urn:nbn:de:kobv:b43-460918 10.1016/j.aiepr.2018.06.002 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2018-10-01 OPUS4-37699 Zeitschriftenartikel Blaker, J. J.; Anthony, David B.; Tang, G.; Shamsuddin, S.-R.; Kalinka, Gerhard; Wienrich, Malte; Abdolvand, Amin; Shaffer, M. S. P.; Bismarck, A. Property and shape modulation of carbon fibers using lasers An exciting challenge is to create unduloid-reinforcing fibers with tailored dimensions to produce synthetic composites with improved toughness and increased ductility. Continuous carbon fibers, the state-of-the-art reinforcement for structural composites, were modified via controlled laser irradiation to result in expanded outwardly tapered regions, as well as fibers with Q-tip (cotton-bud) end shapes. A pulsed laser treatment was used to introduce damage at the single carbon fiber level, creating expanded regions at predetermined points along the lengths of continuous carbon fibers, while maintaining much of their stiffness. The range of produced shapes was quantified and correlated to single fiber tensile properties. Mapped Raman spectroscopy was used to elucidate the local compositional and structural changes. Irradiation conditions were adjusted to create a swollen weakened region, such that fiber failure occurred in the laser treated Region producing two fiber ends with outwardly tapered ends. Loading the tapered fibers allows for viscoelastic energy dissipation during fiber pull-out by enhanced friction as the fibers plough through a matrix. In these tapered fibers, diameters were locally increased up to 53%, forming outward taper angles of up to 1.8°. The tensile strength and strain to failure of the modified fibers were significantly reduced, by 75% and 55%, respectively, ensuring localization of the break in the expanded region; however, the fiber stiffness was only reduced by 17%. Using harsher irradiation conditions, carbon fibers were completely cut, resulting in cottonbud fiber end shapes. Single fiber pull-out tests performed using these fibers revealed a 6.75-fold increase in work of pull-out compared to pristine carbon fibers. Controlled laser irradiation is a route to modify the shape of continuous carbon fibers along their lengths, as well as to cut them into controlled lengths leaving tapered or cotton-bud shapes. 1155 Sixteenth Street, NW, Washington, DC 20036, USA ACS Publications 2016 ACS Applied Materials & Interfaces 8 25 16351 16358 10.1021/acsami.6b05228 2016-10-10 OPUS4-48684 Zeitschriftenartikel Palantöken, Sinam; Bethke, K.; Zivanovic, V.; Kneipp, Janina; Rademann, Klaus; Kalinka, Gerhard Cellulose hydrogels physically crosslinked by glycine: Synthesis, characterization, thermal and mechanical properties Biopolymers are very efficient for significant applications ranging from tissue engineering, biological devices to water purification. There is a tremendous potential value of cellulose because of ist being the most abundant biopolymer on earth, swellability, and functional groups to be modified. A novel, highly efficient route for the fabrication of mechanically stable and natural hydrogels is described in which cellulose and glycine are dissolved in an alkaline solution of NaOH and neutralized in an acidic solution. The dissolving temperature and the glycine amount are essential parameters for the self-assembly of cellulose chains and for Tuning the morphology and the aggregate structures of the resulting hydrogels. Glycine plays the role of a physical crosslinker based on the Information obtained from FTIR and Raman spectra. Among the prepared set of hydrogels, CL5Gly30 hydrogels have the highest capacity to absorb water. The prepared CL5Gly30 gels can absorb up to seven times their dry weight due to its porous 3-D network structure. CL5Gly10 hydrogel exhibits 80% deformation under 21 N force executed. The method developed in this article can contribute to the application of heavy metal adsorption in aqueous solutions for water purification and waste management. USA Wiley 2019 Journal of Applied Polymer Science 136 48380, 1 11 urn:nbn:de:kobv:b43-486845 10.1002/APP.48380 https://creativecommons.org/licenses/by/4.0/deed.de 2019-08-13 OPUS4-58155 Zeitschriftenartikel Krauklis, A. E.; Starovka, O.; Gibhardt, D.; Aouissi, H. A.; Burlakovs, J.; Sabalina, A.; Fiedler, Bodo; Kalinka, Gerhard Reversible and irreversible effects on the epoxy GFRP fiber-matrix interphase due to hydrothermal aging Epoxy R-Glass Fiber-Reinforced Polymer (GFRP) composite plates were hydrothermally aged at 60 ◦C for 23, 75, and 133 days. The water content reached 0.97 wt%, 1.45 wt% and 1.63 wt%, respectively. The studied GFRP matrix was inert to hydrolysis or chain scission, allowing for investigation of irreversible changes in the fiber-matrix interphase due to hydrothermal aging upon re-drying. During each period, a subset of the specimens was removed from the water bath and dried in a chamber. The weight loss upon drying was explained with epoxy leaching (impurities), sizing-rich interphase hydrolysis, glass fiber surface hydrolysis, accumulated degradation products escaping, and water changing state from bound to free. The influence of hydrothermal aging on the fiber-matrix interfacial properties was investigated. Lower interfacial strength of hydrothermally aged (wet) samples was attributed to plasticization of the epoxy, plasticization and degradation of the sizing-rich interphase (including formation of hydrolytic flaws), and hydrolytic degradation of the glass fiber surface. The kinetics of epoxy-compatible epoxysilane W2020 sizing-rich interphase hydrolysis provided an estimate of ca. 1.49%, 4.80%, and 8.49% of the total composite interphase degraded after 23, 75, and 133 days, respectively. At these conditions, the interface lost 39%, 48%, and 51% of its strength. Upon re-drying the specimens, a significant part of the interfacial strength was regained. Furthermore, an upward trend was observed, being 13%, 10% and 3% strength, respectively; thus, indicating a possibility of partial recovery of properties. Amsterdam, Niederlande Elsevier B.V. 2023 Composites Part C 12 1 9 urn:nbn:de:kobv:b43-581554 10.1016/j.jcomc.2023.100395 https://creativecommons.org/licenses/by/4.0/deed.de 2023-09-06 OPUS4-44784 Zeitschriftenartikel Kalinka, Gerhard; Sahin, M.; Schlögl, S.; Wang, J.; Kaynak, B.; Mühlbacher, I.; Ziegler, W.; Kern, W.; Grützmacher, H. Tailoring the interfaces in glass fiber-reinforced photopolymer composites The present work provides a comparative study on the interface and adhesion properties of surface modified single glass fibers embedded in an acrylate matrix. To facilitate a covalent bonding at the fibermatrix interface, the fibers are functionalized with selected organosilanes that comprise either passive (unsaturated C¼C bonds of methacrylate moieties) or photoactive functionalities (photocleavable bis(acyl)phosphane oxide groups). Immobilization of the functional silanes is carried out by a classic silanization reaction involving a condensation reaction across the surface hydroxyl groups of the inorganic glass fibers. The change of the physico-chemical properties of the fibers due to desizing and subsequent surface modification is monitored by X-ray photoelectron spectroscopy and zeta potential measurements. In addition, scanning electron microscopy is used to follow the changes in surface morphology. After the modification step, the desized and modified single fibers are embedded in a photocurable acrylate resin formulation. By performing single fiber pull-out tests, maximum pull-out force, friction strength and apparent interfacial shear strength are determined as a function of the coupled silanes. The results reveal that the attached organosilanes lead to a significant increase in adhesion strength, whilst the performance of the photo-cleavable organosilane is superior to the passive methacryl-functional derivative. New York Elsevier Ltd. 2018 Polymer 141 221 231 10.1016/j.polymer.2018.03.020 2018-04-26 OPUS4-41464 Vortrag Bertin, Annabelle Controlled Self-Assembly of Janus Dendrimers via Microfluidics Unilamellar vesicles self-assembled in water from natural and synthetic phospholipids (liposomes), amphiphilic block copolymers (polymersomes), and more recently amphiphilic Janus dendrimers (dendrimersomes) as hollow soft structures in the nano size regime have attracted increasing interest as they can mimic primitive and contemporary biological membranes, and can be configured into biomimetic nanocapsules with application in nanomedicine such as gene, proteins and drug carriers or theranostics. Compared to other amphiphilic structures, the molecular structure of Janus dendrimers can be precisely controlled: by using the vast range of tools from organic chemistry their size, architecture, density, generation as well as the number of endgroups of the individual dendrons can be modified as desired. Unfortunately, the controlled production of the supramolecular aggregates made thereof is still a challenging task. Conventional batch-based techniques such as the solvent injection method or the film hydration method typically go along with a lack of control over mixing and thus over size, morphology and size distribution. The micromixer technology is a promising method for the controlled preparation of supramolecular assemblies as it allows control of mixing at microscale level. In addition, such microfluidic systems benefit from a high mixing efficiency, a low mixing time as well as from a reproducible and continuous synthesis. Herein, we report on the microfluidic-controlled self-assembly of Janus dendrimers as dendrimersomes and the impact of the mixing parameters on the self-assembly process. 2017 10th International Dendrimer Symposium Weihai, China 05.08.2017 09.08.2017 2017-08-21 OPUS4-40211 Vortrag Bertin, Annabelle Upper Critical Solution Temperature (UCST)-type thermoresponsive polymers from acrylamide-based monomers UCST-type thermoresponsive polymers that phase separate from solution upon cooling present a tremendous potential not only in aqueous media where they can be used in drug delivery, diagnostic and microfluidic applications, but also in water/alcohol mixtures, where they can be used for instance in sensing systems for alcohol-soluble drugs. However, only a few thermoresponsive polymers have been reported that present an UCST in a relevant temperature range and "green" solvents such as water or ethanol. In this context, acrylamide-based monomers can be very useful building blocks for designing novel UCST-type polymers because of their hydrophilic nature (with the right side chain) and propensity to form hydrogen bonds. We want to present our latest results on the copolymer poly(acrylamide-co-acrylonitrile) (P(AAm-co-AN)) that present a UCST in water as well as on two homopolymers based on an acrylamide derivative of 2,6-diaminopyridine, namely poly(N-(6-aminopyridin-2-yl)acrylamide) (PNAPAAm) and poly(N-(6-acetamidopyridin-2-yl)acrylamide) (PNAcAPAAm) that show UCST-type thermoresponsiveness in water/alcohol mixtures. Our focus for P(AAm-co-AN)) is its aggregation behaviour above and below its phase transition temperature as the size of thermoresponsive polymeric systems is of prime importance for biomedical applications (as size dependent processes take place in the body) and is linked to the optical properties of a material that matter in materials science. In the case of PNAPAAm and PNAcAPAAm, we focused on the co-solvency/co-non solvency effect on the phase transition temperature in water/alcohol mixture. Indeed, polymers with UCST behavior below 60°C in water/alcohol mixtures are extremely promising for the preparation of "smart" materials for sensing. 2017 Soft smart responsive materials workshop: Fundamentals and applications (SmartCECAM) Mainz, Germany 11.05.2017 12.05.2017 2017-05-15 OPUS4-34565 Zeitschriftenartikel Shirshova, N.; Bismarck, A.; Greenhalgh, E.S.; Johansson, P.; Kalinka, Gerhard; Marczewski, M.J.; Shaffer, M.S.P.; Wienrich, Malte Composition as a means to control morphology and properties of epoxy based dual-phase structural electrolytes Structural electrolytes were prepared using a fully formulated commercially available high performance epoxy resin (MTM57) and an ionic liquid based electrolyte: lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) dissolved in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI). Through a systematic study, the composition of the formulations was found to have a greater effect than the curing temperature on the morphology and properties of the resulting structural electrolytes. The presence of lithium salt is essential to form a structurally homogeneous electrolyte. Bicontinuous morphologies containing continuous (coarse) epoxy networks surrounded by connected spherical epoxy nodules were obtained with different length scales upon varying the lithium salt concentration. Increasing the LiTFSI concentration improved the miscibility of MTM57 with the electrolyte and decreased the characteristic length scale of the resulting bicontinuous microstructure. The properties of the structural electrolytes correlated with the morphology, showing increased Young’s modulus and decreased ionic conductivity with increasing lithium salt concentration. The miscibility of the epoxy system with the electrolyte was also improved by substitution of EMIM-TFSI with an equal weight of an aprotic organic solvent, propylene carbonate (PC); however, the window of PC concentrations which resulted in structural electrolytes with bicontinuous microstructures was very narrow; at PC concentrations above 1 wt %, gel-like polymers with no permanent mesoporosity were obtained. Washington, DC Soc. American Chemical Society 2014 The journal of physical chemistry / C 118 49 28377 28387 10.1021/jp507952b 2016-02-20 OPUS4-34718 Zeitschriftenartikel Qian, H.; Kalinka, Gerhard; Chan, K.L.A.; Kazarian, S.G.; Greenhalgh, E.S.; Bismarck, A.; Shaffer, M.S.P. Mapping local microstructure and mechanical performance around carbon nanotube grafted silica fibres: Methodologies for hierarchical composites The introduction of carbon nanotubes (CNTs) modifies bulk polymer properties, depending on intrinsic quality, dispersion, alignment, interfacial chemistry and mechanical properties of the nanofiller. These effects can be exploited to enhance the matrices of conventional microscale fibre-reinforced polymer composites, by using primary reinforcing fibres grafted with CNTs. This paper presents a methodology that combines atomic force microscopy, polarised Raman spectroscopy, and nanoindentation techniques, to study the distribution, alignment and orientation of CNTs in the vicinity of epoxy-embedded micrometre-scale silica fibres, as well as, the resulting local mechanical properties of the matrix. Raman maps of key features in the CNT spectra clearly show the CNT distribution and orientation, including a ‘parted’ morphology associated with long grafted CNTs. The hardness and indentation modulus of the epoxy matrix were improved locally by 28% and 24%, respectively, due to the reinforcing effects of CNTs. Moreover, a slower stress relaxation was observed in the epoxy region containing CNTs, which may be due to restricted molecular mobility of the matrix. The proposed methodology is likely to be relevant to further studies of nanocomposites and hierarchical composites. Cambridge RSC Publ. 2011 Nanoscale 3 11 4759 4767 10.1039/c1nr10497g 2016-02-20 OPUS4-42202 Zeitschriftenartikel Zhang, Luman; de Greef, Nils; Kalinka, Gerhard; Van Bilzen, Bart; Locquet, Jean-Pierre; Verpoest, Ignaas; Won Seo, Jin Carbon nanotube-grafted carbon fiber polymer composites: Damage characterization on the micro scale Multiwall carbon nanotubes (CNTs) e carbon fibers (CFs)hybrid materials were produced by directly growing CNTs on CFs by means of chemical vapor deposition. For the latter, the oxidative dehydrogenation reaction of C2H2 and CO2 was applied, which allows growing CNTs without damaging the CF surface. Uni-directional nano-engineered carbon fiber reinforced composites (nFRCs) were fabricated by impregnating these hybrid materials with epoxy. The nFRCs subjected to single fiber push-out tests revealed a decrease of the interfacial shear strength (IFSS) of about 36% compared to the carbon fiber composites without CNTs. By means of transverse three-point bending tests performed on pre-notched composite beams inside a scanning electron microscope, the fracturing behavior parallel to the fibers was studied in-situ. The nFRCs showed significantly reduced fiber/matrix debonding while CNTs pull-out, CNTs bridging as well as matrix failure occurred. These results demonstrate that the presence of CNTs in nFRCs affects the stress distribution and consequently the damage Initiation as well as the damage propagation. The presence of CNTs suppresses the stress concentration at the fiber/Matrix interface and reduces the debonding of CFs from the matrix. However, our results indicate that the stress concentration shifts towards the CNTs' ends/matrix interface and causes promoted matrix failure leading to lower IFSS. Niederlande Elsevier 2017 Composites Part B 126 202 210 10.1016/j.compositesb.2017.06.004 2017-09-28 OPUS4-29735 Zeitschriftenartikel Shirshova, N.; Bismarck, A.; Carreyette, S.; Fontana, Q.P.V.; Greenhalgh, E.S.; Jacobsson, P.; Johansson, P.; Marczewski, M.J.; Kalinka, Gerhard; Kucernak, A.R.J.; Scheers, J.; Shaffer, M.S.P.; Steinke, J.H.G.; Wienrich, Malte Structural supercapacitor electrolytes based on bicontinuous ionic liquid-epoxy resin systems 'Structural electrolytes' retain the desirable mechanical characteristics of structural (epoxy) resins whilst introducing sufficient ionic conductivity to operate as electrolytes in electrochemical devices. Here, a series of ionic liquid-epoxy resin composites were prepared to identify the optimum system microstructure required to achieve a high level of multifunctionality. The ionic conductivity, mechanical properties, thermal stability and morphology of the cured epoxy based structural electrolytes were studied as a function of phase composition for three fully formulated high performance structural epoxy systems. At only 30 wt% of structural resin and 70 wt% of ionic liquid based electrolyte, stiff monolithic plaques with thicknesses of 2-3 mm were obtained with a room temperature ionic conductivity of 0.8 mS cm-1 and a Young's modulus of 0.2 GPa. This promising performance can be attributed to a long characteristic length scale spinodal microstructure, suggesting routes to further optimisation in the future. London [u.a.] RSC 2013 Journal of materials chemistry A 1 48 15300 15309 10.1039/c3ta13163g 2016-02-20 OPUS4-34567 Zeitschriftenartikel Greenhalgh, E.S.; Ankersen, J.; Asp, L. E.; Bismarck, A.; Fontana, Q.P.V.; Houlle, M.; Kalinka, Gerhard; Kucernak, A.; Mistry, M.; Nguyen, S.; Qian, H.; Shaffer, M.S.P.; Shirshova, N.; Steinke, J.H.G.; Wienrich, Malte Mechanical, electrical and microstructural characterisation of multifunctional structural power composites Multifunctional composites which can fulfil more than one role within a system have attracted considerable interest. This work focusses on structural supercapacitors which simultaneously carry mechanical load whilst storing/delivering electrical energy. Critical mechanical properties (in-plane shear and in-plane compression performance) of two monofunctional and four multifunctional materials were characterised, which gave an insight into the relationships between these properties, the microstructures and fracture processes. The reinforcements included baseline T300 fabric, which was then either grafted or sized with carbon nanotubes, whilst the baseline matrix was MTM57, which was blended with ionic liquid and lithium salt (two concentrations) to imbue multifunctionality. The resulting composites exhibited a high degree of matrix heterogeneity, with the ionic liquid phase preferentially forming at the fibres, resulting in poor matrix-dominated properties. However, fibre-dominated properties were not depressed. Thus, it was demonstrated that these materials can now offer weight savings over conventional monofunctional systems when under modest loading. London Sage 2014 Journal of composite materials 1 12 10.1177/0021998314554125 2016-02-20 OPUS4-45980 Zeitschriftenartikel de Camp, N. V.; Kalinka, Gerhard; Bergeler, J. Light-cured polymer electrodes for non-invasive EEG recordings We invented the first non-metallic, self-adhesive and dry biosignalling electrode. The PEDOT polymer electrode changes its aggregate state and conductivity by a light curing procedure. The electrode can be applied as a gel underneath hair without shaving. With the aid of blue light, the electrode can be hardened within a few seconds at the desired location on the scalp. The cured polymer electrode is highly conductive and can be applied on a very small location. Unlike other EEG electrodes, our electrode does not lose conductivity upon drying. Furthermore, our electrode strongly bonds to Skin and does not require any additional adhesive. Short circuits due to an outflow of gel are prevented with this technique. Therefore, the PEDOT polymer electrode is extremely well suited for applications that, up to now, have been challenging, such as non-invasive EEG recordings from awake and freely moving animals, EEG recordings from preterm babies in the neonatal intensive care unit or long-term recordings in the case of sleep monitoring or epilepsy diagnostics. We addressed two technical questions in this work. First, is the EEG recorded with polymer electrodes comparable to a standard EEG? Second, is it possible to record full-band EEGs with our electrodes? London Nature Publishing Group Springer Nature 2018 Scientific Reports 8 14041 1 9 urn:nbn:de:kobv:b43-459803 10.1038/s41598-018-32304-6 https://creativecommons.org/licenses/by/4.0/deed.de 2018-09-20 OPUS4-44569 Vortrag Bertin, Annabelle Upper critical solution temperature (UCST)-type thermoresponsive polymers from hydrogen-bonding monomers UCST-type thermoresponsive polymers (i.e. that phase separate from solution upon cooling) present a tremendous potential not only in aqueous media where they can be used in drug delivery, diagnostic and microfluidic applications, but also in water/alcohol mixtures, where they can be used for instance in sensing systems for alcohol-soluble drugs. However, only a few thermoresponsive polymers have been reported that present an UCST in a relevant temperature range and "green" solvents such as water or ethanol. In this context, acrylamide-based monomers can be very useful building blocks for designing novel non-ionic UCST-type polymers because of their hydrophilic nature (with the appropriate side chain) and propensity to form hydrogen bonds. We will present our latest results on the UCST-type thermoresponsive behaviour of acrylamide- and 2,6-diaminopyridine-based homopolymers and copolymers in water or water/alcohol mixtures, and give some insights about the rational design of UCST polymers relying on H-bonding. 2018 Deutsche Physikalische Gesellschaft (DPG)-Frühjahrtagung 2018 Berlin, Germany 11.03.2018 16.03.2018 2018-03-27 OPUS4-45155 Vortrag Bertin, Annabelle Upper Critical Solution Temperature (UCST)-type Thermoresponsive Polymers from Hydrogen-Bonding Monomers UCST-type thermoresponsive polymers (i.e. that phase separate from solution upon cooling) present a tremendous potential not only in aqueous media where they can be used in drug delivery, diagnostic and microfluidic applications,but also in water/alcohol mixtures, where they can be used for instance in sensing systems for alcohol-soluble drugs. However, only a few thermoresponsive polymers have been reported that present an UCST in a relevant temperature range and "green" solvents such as water or Ethanol. In this context, acrylamide-based monomers can be very useful building blocks for designing novel non-ionic UCST-type polymers because of their hydrophilic nature (with the appropriate side chain) and propensity to form hydrogen bonds. We will present our latest results on the UCST-type thermoresponsive behaviour of acrylamide- and/or 2,6-diaminopyridine-based homopolymers and copolymers in water or water/alcohol mixtures, and give some insights about the rational design of UCST polymers relying on H-bonding. 2018 Bordeaux Polymer Conference BPC 2018 Bodeaux, France 28.05.2018 31.05.2018 2018-06-13 OPUS4-42007 Vortrag Bertin, Annabelle Upper critical solution temperature (UCST)-type thermoresponsive polymers from acrylamide-based monomers UCST-type thermoresponsive polymers (i.e. that phase separate from solution upon cooling) present a tremendous potential not only in aqueous media where they can be used in drug delivery, diagnostic and microfluidic applications but also in water/alcohol mixtures, where they can be used for instance in sensing systems for alcohol-soluble drugs. However, only a few thermoresponsive polymers have been reported that present an UCST in a relevant temperature range and "green" solvents such as water or ethanol. In this context, acrylamide-based monomers can be very useful building blocks for designing novel non-ionic UCST-type polymers because of their hydrophilic nature (with the right side chain) and propensity to form hydrogen bonds. We will present our latest results on the UCST-type thermoresponsive behaviour of acrylamide- and 2,6-diaminopyridine-based homopolymers and copolymers in water or water/alcohol mixtures, and give some insights about the rational design of UCST polymers relying on H-bonding. 2017 Bioorganik 2017 – 26th Symposium "Bioorganic Chemistry" for young researchers Berlin, Germany 20.09.2017 22.09.2017 2017-09-21 OPUS4-42510 Beitrag zu einem Tagungsband Barnefske, Lena; Wachtendorf, Volker Self-healing silicone rubber for fluorescent partial discharge POF sensors in high-voltage cable accessories To avoid a catastrophic failure of insulation in high-voltage (HV) applications, a monitoring of partial discharges (PDs) is necessary. Fluorescently labelled polymer optical fibers (F-POF) offer an electrically passive method for PD detection in HV facilities. F-POFs could be embedded in HV cable accessories, which are usually made of silicone rubber. Herein they detect the light emitted by the PD and convert it into an electrical signal that can be monitored. Due to the difficult accessibility of HV cable accessories, a self-healing silicone rubber with prolonged service life after PD detection represents an attractive material design for HV accessories. With this contribution, we would like to present and discuss the possibilities of combining self-healing materials with POF-based sensors for PD detection in HV applications. 2017 26th International Conference on Plastic Optical Fibres 978-989-97345-2-4 26th International Conference on Plastic Optical Fibres Aveiro, Portugal 13.09.2017 15.09.2017 paper 16, 1 5 2017-10-13 OPUS4-57185 Zeitschriftenartikel Rabe, T.; Kalinka, Gerhard; Mieller, Björn Manufacturing and deformation behavior of alumina and zirconia helical springs at room temperature Ceramic helical springs with identical dimensions were produced by hard machining from alumina, alumina toughened zirconia (ATZ), and tetragonal zirconia polycrystals (TZP) stabilized with different oxides. According to the results of the spring constant determination under deformation rates of 3 mm/min, the deformation behavior of all ceramic springs obeys to Hook's law. However, variation of the deformation rate, tests under constant load, and spring recovery behavior revealed differences in the deformation behavior of alumina, TZP, and ATZ springs. Alumina springs exhibited time-independent deformation in all tests. In contrast, anelastic deformation at room temperature was demonstrated in all springs containing TZP. This deformation is completely reversible over a period of several days. Anelastic behavior is particularly pronounced in Y-TZP springs, whereas Ce-TZP springs exhibit comparatively very low but still reliably detectable anelasticity. Oxygen vacancies in the TZP ceramic are considered the most likely explanation for the anelastic behavior of TZP springs at room temperature. Oxford [u.a.] Wiley-Blackwell 2023 Journal of the American Ceramic Society 1 14 urn:nbn:de:kobv:b43-571858 10.1111/jace.19085 https://creativecommons.org/licenses/by/4.0/deed.de 2023-03-21 OPUS4-44296 Vortrag Bertin, Annabelle Building macromolecular mimetics of cell constituents One of the holy grails in chemistry is to reconstruct some of life's functions with synthetic materials. In this contribution, we demonstrate that "simple" macromolecular architectures such as dendritic amphiphiles, Janus dendrimers, thermoresponsive and hybrid organic-inorganic (co)polymers enable to mimic some of the functions of proteins for biomineralization, natural bactericides, biological membranes or the stimuli-responsive cytoskeleton. 2018 Makromolekulares Kolloquium Freiburg 2018 Freiburg in Breisgau, Germany 21.02.2018 23.02.2018 2018-02-26 OPUS4-44442 Vortrag Bertin, Annabelle Building macromolecular mimetics of cell constituents One of the holy grails in chemistry is to reconstitute some of life's functions with or within synthetic materials. In this contribution, we demonstrate that "simple" macromolecular architectures such as dendritic amphiphiles, Janus dendrimers, thermoresponsive and hybrid organic-inorganic (co)polymers enable to mimic some of the functions of proteins for biomineralization, natural bactericides, biological membranes or the stimuli-responsive cytoskeleton. 2018 Chemiedozententagung 2018 Jena, Germany 05.03.2018 07.03.2018 2018-03-12