TY - JOUR A1 - Zhang, Luman A1 - de Greef, Nils A1 - Kalinka, Gerhard A1 - Van Bilzen, Bart A1 - Locquet, Jean-Pierre A1 - Verpoest, Ignaas A1 - Won Seo, Jin T1 - Carbon nanotube-grafted carbon fiber polymer composites: Damage characterization on the micro scale N2 - 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. KW - Carbon fibres nanotubes interface PY - 2017 DO - https://doi.org/10.1016/j.compositesb.2017.06.004 SN - 1359-8368 SN - 1879-1069 VL - 126 SP - 202 EP - 210 PB - Elsevier CY - Niederlande AN - OPUS4-42202 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhandarov, S. A1 - Mäder, E. A1 - Kalinka, Gerhard A1 - Scheffler, C. A1 - Poitzsch, C. A1 - Fliescher, S. T1 - Investigation of interfacial strength parameters in polymer matrix composites: Compatibility and reproducibility N2 - 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. KW - Interface KW - Interfacial shear strength KW - Pull-out composite materials KW - Polymer matrix composites KW - Critical energy release rate KW - Geometrical factors PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-460918 DO - https://doi.org/10.1016/j.aiepr.2018.06.002 SN - 2542-5048 VL - 1 IS - 1 SP - 82 EP - 92 PB - Elsevier CY - Amsterdam AN - OPUS4-46091 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wienrich, Malte A1 - Kalinka, Gerhard A1 - Greenhalgh, E.S. A1 - Carreyette, S. A1 - Bistritz, Martina A1 - Shirshova, N. A1 - Houllé, M. A1 - Asp, L. E. A1 - Bismarck, A. A1 - Fontana, Q.P.V. T1 - Impact of ionic liquid on the mechanical performance of matrix polymer for fibre reinforced materials for energy storage N2 - 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. T2 - ECCM15 - 15th European conference on composite materials CY - Venice, Italy DA - 2012-06-24 KW - Multifunctional epoxy resin KW - Fibre-matrix adhesion KW - Single fibre pull-out test KW - Ionic liquid PY - 2012 SN - 978-88-88785-33-2 SP - 1 EP - 4(?) AN - OPUS4-28695 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wienrich, Malte A1 - Kalinka, Gerhard A1 - Greenhalgh, E. A1 - Carreyette, Shuijin A1 - Bistritz, Martina A1 - Shirshova, Natasha A1 - Houllé, Matthieu A1 - Bismarck, A. T1 - IMPACT OF IONIC LIQUID ON THE MECHANICAL PERFORMANCE OF MATRIX POLYMER FOR FIBRE REINFORCED MATERIALS FOR ENERGY STORAGE T2 - ECCM 15 - European Conference on Composite Materials CY - Venice, Italy DA - 2012-06-24 PY - 2012 AN - OPUS4-27467 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wettmarshausen, Sascha A1 - Friedrich, Jörg Florian A1 - Meyer-Plath, Asmus A1 - Kalinka, Gerhard A1 - Hidde, Gundula A1 - Weidner, Steffen T1 - Coating of carbon fibers with adhesion-promoting thin poly(acrylic acid) and poly(hydroxyethylmethacrylate) layers using electrospray ionization N2 - 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. KW - Adhesion promotion KW - Thin polymer layers KW - Electrospray ionization (ESI) KW - Carbon fiber–epoxy resin laminates KW - Layer topography PY - 2015 DO - https://doi.org/10.1080/01694243.2015.1040980 SN - 0169-4243 SN - 1568-5616 VL - 29 IS - 15 SP - 1628 EP - 1650 PB - VNU Science Press CY - Utrecht AN - OPUS4-34564 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen T1 - Abbau und Zersetzungsverhalten von Polymeren und Komposit‐ Materialien auf Polyurethanbasis N2 - Polyurethane zeichnen sich durch ihre große Flexibilität des Anwendungsbereiches aus. Im Rahmen dieses Vortrags wird ein neues Themenfeldprojekt der BAM vorgestellt und erste Ergebnisse präsentiert. T2 - Deutsche Gesellschaft für Materialprüfung, Fachausschuss Polymerwerkstoffe CY - Darmstadt, Germany DA - 10.11.2016 KW - Polyurethane KW - Abbauverhalten PY - 2016 AN - OPUS4-38332 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker A1 - Kalinka, Gerhard A1 - Loose, Florian T1 - Carbon fibre composites exemplarily research at BAM N2 - 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. T2 - Meeting KCarbon CY - Berlin, Germany DA - 15.06.2023 KW - Lightweighting KW - Carbon Fibers KW - Recycling KW - Push-out Test KW - multi scale testing PY - 2023 AN - OPUS4-58094 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker T1 - Current and future technological advancement in polymer matrix composites enabled through fundamental discoveries N2 - This presentation is a summary of the work from the past 20 years’ development of PMC-testing at the BAM-FB 5.3 with respect to safety-relevant design of advanced light weight structures in aircraft, wind turbine and automotive applications. The talk begins with wood as an example from nature, and emphasizes that load case, fiber architectural design and the production process and quality have to go hand in hand to generate an advanced light weight structure. Since PMC-relevant basic findings of mankind span across hundreds of years, high-performance composite applications today are based more on long term experiences than on breakthrough inventions of modern days. In the second part of the talk, future plans and projects of FB-5.3 are presented, specifically addressing H2-safety, circular economy, recycling by design and digitalization of PMC-technologies. T2 - Abteilungsseminar CY - Online meeting DA - 07.09.2021 KW - Polymer Matrix Composites KW - Thermo mechanical fatigue PY - 2021 AN - OPUS4-54150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tran, M.Q. A1 - Ho, K.K.C. A1 - Kalinka, Gerhard A1 - Shaffer, M.S.P. A1 - Bismarck, A. T1 - Carbon fibre reinforced poly(vinylidene fluoride): Impact of matrix modification on fibre/polymer adhesion N2 - 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. KW - A. Carbon fibres KW - A. Coupling agents KW - B. Interface KW - B. Adhesion KW - Wetting PY - 2008 DO - https://doi.org/10.1016/j.compscitech.2008.02.021 SN - 0266-3538 VL - 68 IS - 7-8 SP - 1766 EP - 1776 PB - Elsevier CY - Barking AN - OPUS4-18259 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thomason, J.L. A1 - Kalinka, Gerhard T1 - A technique for the measurement of reinforcement fibre tensile strength at sub-millimetre gauge lengths N2 - 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. KW - Verstärkungsfaser KW - Kurzfaser KW - Längenabhängigkeit KW - Glass fibres KW - Strength KW - Mechanical testing KW - Festigkeit KW - Faser PY - 2001 DO - https://doi.org/10.1016/S1359-835X(00)00122-6 SN - 1359-835X VL - 32 IS - 1 SP - 85 EP - 90 PB - Elsevier CY - Oxford AN - OPUS4-12012 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Taketa, I. A1 - Kalinka, Gerhard A1 - Gorbatikh, L. A1 - Lomov, S. A1 - Verpoest, I. T1 - Influence of cooling rate on the properties of carbon fiber unidirectional composites with polypropylene, polyamide 6, and polyphenylene sulfide matrices N2 - 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. KW - Matrix residual stress KW - Thermoplastic prepreg KW - Unidirectional composites KW - Cooling rate KW - Interfacial strength PY - 2020 DO - https://doi.org/10.1080/09243046.2019.1651083 SN - 0924-3046 SN - 1568-5519 N1 - Die originale japanische Version des Artikels erschien in: Journal of the Japan Society for Composite Materials, Jg. 44, Nr. 4 (2018), S. 123-128. - The original Japanese version of the article was published in: Journal of the Japan Society for Composite Materials, vol. 44, no. 4 (2018), pp. 123-128. VL - 29 IS - 1 SP - 101 EP - 113 PB - Taylor & Francis CY - London AN - OPUS4-45433 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sänger, Johanna C. A1 - Riechers, Birte A1 - Pauw, Brian Richard A1 - Maaß, Robert A1 - Günster, Jens T1 - Microplastic response of 2PP‐printed ceramics N2 - AbstractTwo‐photon polymerization (2PP) additive manufacturing (AM) utilizes feedstocks of ceramic nanoparticles of a few nanometers in diameter, enabling the fabrication of highly accurate technical ceramic design with structural details as small as 500 nm. The performance of these materials is expected to differ from conventional AM ceramics, as nanoparticles and three‐dimensional printing at high resolution introduce new microstructural aspects. This study applies 2PP‐AM of yttria‐stabilized zirconia to investigate the mechanical response behavior under compressive load, probing the influence of smallest structural units induced by the line packing during the printing process, design of sintered microblocks, and sintering temperature and thereby microstructure. We find a dissipative mechanical response enhanced by sintering at lower temperatures than conventional. The pursued 2PP‐AM approach yields a microstructured material with an increased number of grain boundaries that proposedly play a major role in facilitating energy dissipation within the here printed ceramic material. This microplastic response is further triggered by the filigree structures induced by hollow line packing at the order of the critical defect size of ceramics. Together, these unique aspects made accessible by the 2PP‐AM approach contribute to a heterogeneous nano‐ and microstructure, and hint toward opportunities for tailoring the mechanical response in future ceramic applications. KW - Manufacturing KW - Mechanical properties KW - Microstructure KW - Plasticity KW - Zirconia: yttria stabilized PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-605176 DO - https://doi.org/10.1111/jace.19849 SN - 1551-2916 SP - 1 EP - 10 PB - Wiley CY - Oxford [u.a.] AN - OPUS4-60517 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sturm, Heinz A1 - Schulz, Eckhard T1 - Local AC current contrast on carbon fiber surfaces imaged by scanning force microscopy N2 - 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. KW - Matrix adhesion KW - Films KW - Photoconduction KW - Composites PY - 1995 DO - https://doi.org/10.1002/actp.1995.010460505 SN - 0323-7648 SN - 1521-4044 VL - 46 IS - 5 SP - 379 EP - 384 PB - Wiley-VCH Verl. CY - Weinheim, Germany AN - OPUS4-6848 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz A1 - Silbernagl, Dorothee A1 - Ghasem Zadeh Khorasani, Media T1 - Improving polymer matrix additives for composite structures: a focus on boehmite N2 - 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. T2 - 92nd DKG annual meeting and symposium on high performance ceramics CY - Berlin, Germany DA - 19.03.2017 KW - Boehmite nanoparticle KW - Intermodulation AFM KW - Composite structures KW - Pull-out test KW - Thermoset KW - Crack propagation energy PY - 2017 AN - OPUS4-39519 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sigrüner, M. A1 - Hüsken, Götz A1 - Pirskawetz, Stephan A1 - Herz, J. A1 - Muscat, D. A1 - Strübbe, N. T1 - Pull-out behavior of polymer fibers in concrete N2 - The bond between polymer fibers and the surrounding cementitious matrix is essential for the development of concrete reinforcement. The single fiber pull-out test (SFPT) is the standard characterization technique for testing the bond strength. However, the different phases of debonding cannot be distinguished by the SFPT. This study investigates the debonding of different polymer fibers from the surrounding cementitious matrix with a modified SFPT and proposes methods to change the SFPT setup to generate more valuable information on the debonding mechanism. The SFPT was equipped with linear variable differential transformers (LVDT), digital image correlation (DIC) and acoustic emission (AE) analysis. The results demonstrate that the modified SFPT allows a better understanding of the different phases of debonding during fiber pull-out. Furthermore, bond strength values calculated by different methods reveal that the chemical bond of the investigated polymers is not different as reported by previous studies. Deformation measurements performed using LVDTs and DIC are suitable measuring techniques to characterize the debonding mechanism in SFPT. A correlation between recorded AE and debonding phases was not found. KW - Polymer Fibres KW - Concrete KW - Pull-Out Behaviour KW - Debonding Mechanism PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-582918 DO - https://doi.org/10.1002/pol.20230264 SN - 2642-4169 SP - 1 EP - 13 PB - Wiley Periodicals, LLC. AN - OPUS4-58291 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shirshova, Natasha A1 - Kalinka, Gerhard A1 - Bismarck, A. A1 - Carreyette, Shuijin A1 - Fontana, Quentin P. A1 - Greenhalgh, E. A1 - Kucernack, Anthony A1 - Schaffer, Milo A1 - Wienrich, Malte T1 - Modified epoxy resin as electrolytes for structural supercapacitors T2 - European Polymer Congress 2011 CY - Granada, Spain DA - 2011-06-26 PY - 2011 AN - OPUS4-24452 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shirshova, N. A1 - Bismarck, A. A1 - Greenhalgh, E.S. A1 - Johansson, P. A1 - Kalinka, Gerhard A1 - Marczewski, M.J. A1 - Shaffer, M.S.P. A1 - Wienrich, Malte T1 - Composition as a means to control morphology and properties of epoxy based dual-phase structural electrolytes N2 - 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. KW - Functional composites KW - Mechanical properties KW - Elastic properties KW - Epoxy KW - Morphology KW - Electrolyte PY - 2014 DO - https://doi.org/10.1021/jp507952b SN - 1932-7447 SN - 1089-5639 VL - 118 IS - 49 SP - 28377 EP - 28387 PB - Soc. CY - Washington, DC AN - OPUS4-34565 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shirshova, N. A1 - Bismarck, A. A1 - Carreyette, S. A1 - Greenhalgh, E.S. A1 - Johansson, P. A1 - Marczewski, M.J. A1 - Jacobsson, P. A1 - Kalinka, Gerhard A1 - Shaffer, M.S.P. A1 - Wienrich, Malte A1 - Steinke, J.H.G. T1 - Correlations between mechanical properties and ionic conduction of structural electrolytes with bicontinuous morphologies N2 - 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. T2 - ICCM19 - 19th International conference on composite materials CY - Montreal, Canada DA - 28.07.2013 KW - Structural electrolyte KW - Multifunctional supercapacitor KW - Bicontinuous morphology KW - Epoxy resin KW - Ionic conductivity KW - Mechanical properties PY - 2013 SP - 72 EP - 79 AN - OPUS4-29273 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shirshova, N. A1 - Bismarck, A. A1 - Carreyette, S. A1 - Fontana, Q.P.V. A1 - Greenhalgh, E.S. A1 - Jacobsson, P. A1 - Johansson, P. A1 - Marczewski, M.J. A1 - Kalinka, Gerhard A1 - Kucernak, A.R.J. A1 - Scheers, J. A1 - Shaffer, M.S.P. A1 - Steinke, J.H.G. A1 - Wienrich, Malte T1 - Structural supercapacitor electrolytes based on bicontinuous ionic liquid-epoxy resin systems N2 - '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. KW - Epoxy KW - Ionic liquid KW - Supercapacitor PY - 2013 DO - https://doi.org/10.1039/c3ta13163g SN - 2050-7496 SN - 2050-7488 VL - 1 IS - 48 SP - 15300 EP - 15309 PB - RSC CY - London [u.a.] AN - OPUS4-29735 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schäferling, Michael T1 - Nanoparticle-based luminescent probes for intracellular sensing and imaging of pH N2 - Fluorescence imaging microscopy is an essential tool in biomedical research. Meanwhile, various fluorescent probes are available for the staining of cells, cell membranes, and organelles. Though, to monitor intracellular processes and dysfunctions, probes that respond to ubiquitous chemical parameters determining the cellular function such as pH, pO2, and Ca2+ are required. This review is focused on the progress in the design, fabrication, and application of photoluminescent nanoprobes for sensing and imaging of pH in living cells. The advantages of using nanoprobes carrying fluorescent pHindicators compared to single molecule probes are discussed as well as their limitations due to the mostly lysosomal uptake by cells. Particular attention is paid to ratiometric dual wavelength nanosensors that enable intrinsic referenced measurements. Referencing and proper calibration procedures are basic prerequisites to carry out reliable quantitative pH determinations in complex samples such as living cells. A variety of examples will be presented that highlight the diverseness of nanocarrier materials (polymers, micelles, silica, quantum dots, carbon dots, gold, photon upconversion nanocrystals, or bacteriophages), fluorescent pH indicators for the weak acidic range, and referenced sensing mechanisms, that have been applied intracellularly up to now. KW - pH sensing KW - Luminescent probes KW - Imaging PY - 2016 DO - https://doi.org/10.1002/wnan.1366 SN - 1939-0041 SN - 1939-5116 VL - 8 IS - 3 SP - 378 EP - 413 PB - Wiley-Blackwell CY - Hoboken, New Jersey, USA AN - OPUS4-36367 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schulz, Eckhard A1 - Kalinka, Gerhard A1 - Meretz, S. A1 - Hampe, Andreas T1 - Pull-out of Single Fibres KW - Verstärkungsfaser KW - Verbundwerkstoffe KW - Interface KW - Adhäsion KW - Reibung KW - Haftung KW - Thermoplast PY - 1994 SN - 0945-0084 VL - 84 IS - 5 SP - 25 EP - 26 PB - Hanser CY - München AN - OPUS4-11989 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schulz, Eckhard A1 - Kalinka, Gerhard A1 - Meretz, S. A1 - Hampe, Andreas T1 - Einzelfaserauszug - Eine Methode zum Bestimmen der Grenzflächenfestigkeit KW - Verstärkungsfaser KW - Verbundwerkstoffe KW - Interface KW - Adhäsion KW - Reibung KW - Haftung KW - Thermoplast PY - 1994 SN - 0023-5563 VL - 84 IS - 5 SP - 608 EP - 610 PB - Hanser CY - München AN - OPUS4-11994 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schulz, Eckhard A1 - Kalinka, Gerhard A1 - Auersch, W. T1 - 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 N2 - 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. KW - Thermoplaste KW - Kristallisation KW - Transkristallisation KW - Interface KW - Verbundwerkstoffe KW - Pull-out KW - Haftung KW - Adhäsion KW - Reibung PY - 1996 DO - https://doi.org/10.1080/00222349608220393 SN - 0022-2348 SN - 1525-609X VL - 35 IS - 3-4 SP - 527 EP - 546 PB - Dekker Chemistry CY - New York, NY AN - OPUS4-11987 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Eckhard A1 - Kalinka, Gerhard T1 - 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 T2 - Europhysics Conference on Macromolecular Physics CY - Prague, Czech Republic DA - 1995-07-17 PY - 1995 AN - OPUS4-12084 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Eckhard A1 - Kalinka, Gerhard A1 - Sturm, Heinz A1 - Munz, Martin T1 - Investigations of the mechanical behaviour of heterogeneous polymeric systems and fibre reinforced composites using micro indentation and scanning force microscopy T2 - Special Lectures, 18. Disc. Conf. And 56the PMM.: Mech. Behaviour of polymeric materials CY - Prague, Czech Republic DA - 1998-07-20 PY - 1998 AN - OPUS4-12092 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Eckhard A1 - Kalinka, Gerhard A1 - Leistner, André A1 - Sturm, Heinz A1 - Munz, Martin A1 - Hampe, Andreas T1 - Investigation of polymeric composites reinforced with high oriented short glass fibres using the single fibre push-out test T2 - Euro-Conf. Surfaces and Interfaces in Polymers and Composites CY - Lausanne, Switzerland DA - 1997-06-03 PY - 1997 AN - OPUS4-6439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Eckhard A1 - Kalinka, Gerhard A1 - Sturm, Heinz A1 - Munz, Martin T1 - Investigation on mechanical behaviour of heterogeneous polymeric systems and fibre reinforced composites using micro indentation and scanning force microscopy T2 - 18th Disc. Conf. and 56th PMM CY - Prague, Czech Republic DA - 1998-07-20 PY - 1998 AN - OPUS4-6451 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schukar, Vivien A1 - Kusche, Nadine A1 - Kalinka, Gerhard A1 - Habel, Wolfgang T1 - Field deployable fiber bragg grating strain patch for long-term stable health monitoring applications N2 - 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. KW - Fiber Bragg grating KW - Patch KW - Strain gauge factor KW - Temperature sensitivity KW - Push-out test KW - Validation KW - Fatigue behavior PY - 2013 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-276271 DO - https://doi.org/10.3390/app3010039 SN - 2076-3417 VL - 3 IS - 1 SP - 39 EP - 54 PB - MDPI CY - Basel AN - OPUS4-27627 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schukar, Vivien A1 - Baitinger, Eugen A1 - Kusche, Nadine A1 - Steinke, F. A1 - Habel, Wolfgang T1 - Use of spectral conditions to separate strain and temperature effects in fibre Bragg grating sensors embedded in load-carrying anisotropic laminates N2 - This work presents a further development of the methods of simultaneous determination of temperature and axial strain using a single fibre Bragg grating (FBG). The reflected spectrum of composite-embedded FBG sensors has been analyzed in order to separate temperature and load effects. We found out that during the curing process of the laminates, a superstructure has been introduced on the FBG. Analyzing this effect, a temperature and strain separation was implemented by simply calculating and comparing the integrated intensity of the spectral response signal. A mathematical four-parametric model has been developed to calculate the reflected spectrum of a superstructured fibre Bragg grating. The mathematically achieved data has been evaluated with experimentally determined data from fibre Bragg gratings embedded in glass-fibre reinforced composite materials. KW - Fibre Bragg grating KW - Patch KW - Four-parametric KW - model KW - Superstructure KW - Temperature KW - Strain PY - 2013 DO - https://doi.org/10.1007/s11340-013-9773-y SN - 0014-4851 SN - 1741-2765 VL - 54 IS - 3 SP - 421 EP - 429 PB - Springer CY - Norwell, Mass. AN - OPUS4-29452 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schreier, Andy T1 - Distributed Brillouin sensing in polymer optical fibers N2 - A brief overview about the results obtained within the BAM PhD framwork. T2 - Meeting of the Terahertz-Photonics-Group at IHF, Technische Universität Braunschweig CY - Braunschweig, Germany DA - 17.07.2019 KW - Brillouin KW - Distributed sensing KW - Polymer optical fibre PY - 2019 AN - OPUS4-48501 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schilder, Constanze A1 - Schukar, Marcus A1 - Steffen, Milan A1 - Krebber, Katerina T1 - Structural health monitoring of composite structures by distributed fibre optic sensors N2 - Structural Health Monitoring of composite materials gains in importance with the increasing use of Composite structures for safety-related applications, e.g. in aerospace. Because of the material properties of composites, defects often occur inside the structures and raise the demand for integrated sensors. The advantages of optical fibres predestine them not only for the surface-application on composite structures but also for the Integration into composite structures. Even without quasi-distributed sensors such as FBGs or LPGs, the optical fibre itself can be used to measure the structure and occurring events over the entire fibre length by distributed sensing techniques. This paper presents the surface-application of polyimide coated silica optical fibres onto PEEK specimens and the integration of copper and polyimide coated silica optical fibres into an AS-4/PEEK Composite to be used as distributed fibre optic sensors for SHM. Results from distributed measurements by optical backscatter reflectometry based on Rayleigh backscattering are shown. T2 - 5th International symposium on NDT in aerospace CY - Singapore DA - 13.11.2013 KW - Structural health monitoring (SHM) KW - Composite structures KW - Optical fibre KW - Distributed fibre optic sensors KW - Optical backscatter reflectometry PY - 2013 SN - 1435-4934 SP - 1 EP - 7 AN - OPUS4-29687 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Radl, S. A1 - Kreimer, M. A1 - Manhart, J. A1 - Griesser, T. A1 - Moser, A. A1 - Pinter, G. A1 - Kalinka, Gerhard A1 - Kern, W. A1 - Schlögl, S. T1 - Photocleavable epoxy based materials N2 - The present study aims at the development of photodegradable epoxy based materials comprising o-nitrobenzyl ester links that undergo well defined bond cleavage in response to UV irradiation. New bi-functional epoxy based monomers bearing o-nitrobenzyl ester groups are synthesized and thermally cured with an anhydride hardener to yield photosensitive polymers and duromers. The UV induced changes in solubility are exploited for the preparation of positive-type photoresists. Thin patterned films are obtained by photolithographic processes and characterized by microscopic techniques. The results evidence that sensitive resist materials with good resolution and high contrast behavior can be accomplished. Along with resist technology, the applicability of o-nitrobenzyl chemistry in the design of recyclable polymer materials with thicknesses in the millimeter range is evaluated. By monitoring the thermo-mechanical properties upon UV illumination, a distinctive depletion of storage modulus and glass transition temperature is observed with increasing exposure dose. Additionally, single fiber pull-out tests are carried out revealing a significant decrease of the interfacial adhesion at the fiber-matrix interface due to the phototriggered cleavage reaction. KW - Epoxy based network KW - Photocleavage KW - o-Nitrobenzyl ester KW - Adhesion KW - Mechanical properties KW - Interfacial shear strength PY - 2015 DO - https://doi.org/10.1016/j.polymer.2015.05.055 SN - 0032-3861 SN - 1873-2291 VL - 69 SP - 159 EP - 168 PB - Elsevier Ltd. AN - OPUS4-34566 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Rabe, Torsten A1 - Schulz, Bärbel A1 - Salehi, M. T1 - Alterungsbeständige keramische Federsensoren durch nanostrukturierte Werkstoffe, Präzisionsbearbeitung und hochdielektrische Nanosuspensionen N2 - Das Ziel des Gesamtvorhabens bestand darin, einen neuartigen kapazitiven Sensortyp zur hochauflösenden Bestimmung von Masse- und Gravitationskraftänderungen zu entwickeln. Bisherige Technologien nutzten dafür Federn oder Biegebalken aus gehärteten metallischen Werkstoffen, deren Alterungsverhalten die Präzision der Kräftemessung begrenzen. Grundprinzip des neuen Sensortyps ist es, eine auf die keramische Feder einwirkenden Änderung der Gewichts- oder Gravitationskraft durch eine Erfassung der Kapazitätsänderung am Sensor zu bestimmen. Dazu muss die durch Stauchung oder Dehnung der Feder entstehende Kapazitätsänderung mit hoher Auflösung reproduzierbar gemessen werden. Neben einem geeigneten Sensordesign waren Lösungen für Messsignalerfassung und -auswertung (Elektronik/Software) und die Systemintegration zu entwickeln. Die wichtigsten im Rahmen des BAM-Teilvorhabens erzielten Ergebnisse sind: - Ausgehend von kommerziellen High-end Keramikpulvern wurden durch Optimierung der keramischen Technologie nahezu porenfreie Al2O3, ZrO2 und Si3N4-Werkstoffe hergestellt und bezüglich Gefüge und Phasenbestand sowie mechanischen, thermischen und elektrischen Eigenschaften bewertet. Insbesondere die defektfreie Herstellung von nanostrukturierten Werkstoffen erforderte umfangreiche Variationen der Prozessparameter. Geeignete Werkstoffvarianten wurden für die Federherstellung ausgewählt. - Gemeinsam mit den Projektpartnern wurden Layoutvarianten für Schraubendruckfedern mit rechteckigem Windungsquerschnitt und für die Federeinbindung in das Sensorsystem erarbeitet. - 4 Federvarianten wurden an der BAM durch Hartbearbeitung von gesinterten Hohlzylindern umgesetzt. Fertigungstoleranzen von < ±10 µm für Windungsbreite, Windungshöhe und Windungsabstand und dünnfilm-kompatible innere Windungsflächen (Ra < 0,2 µm) wurden erreicht. Al2O3- und ZrO2-Federn können rissfrei und mit sehr guter Kantenqualität gefertigt werden, bei Si3N4-Federn konnten Kantenschädigungen nicht vollständig verhindert werden. - Mit der entwickelten Herstellungstechnologie können sowohl „harte“ als auch sehr „weiche“ Federn produziert werden. Federkonstanten zwischen 0,02 N/mm und 10 N/mm wurden realisiert. Die Reproduzierbarkeit der Federfertigung ist gegeben, innerhalb einer Charge unterschieden sich die Federkonstanten der gefertigten Federn nur um etwa +/- 1%. - An einem speziell entwickelten Versuchsstand wurden die Federn unter zyklischer Druckbelastung im Temperaturbereich von -20 bis +80 °C untersucht. An den Al2O3- und ZrO2-Federn wurden keine Schädigungen beobachtet, die Federkonstante wird durch die zyklische Langzeitbelastung nicht verändert. - Die Eignung der keramischen Federn für den Applikationsfall wurde mit zahlreichen Spannungs-Dehnungs-Experimenten, teilweise an speziell aufgebauten Versuchsapparaturen, untersucht. An Al2O3- und Si3N4-Federn wurde – wie erwartet – gefunden, dass die Federkonstante unabhängig von der Belastungsgeschwindigkeit ist und unter konstanter Last auch über lange Zeiträume keine Verformung auftritt. Überraschenderweise zeigten ZrO2 (TZP)-Federn ein zeitabhängiges Verhalten unter Last. Dieses ist besonders stark bei Y-stabilisierten Werkstoffvarianten ausgebildet, wurde aber mit Hochpräzisionsmessungen auch bei Ce-stabilsierten Werkstoffen nachgewiesen. Die Deformation ist reversibel, eine vollständige Relaxation wird erst nach Tagen erreicht. Aufgrund der zeitabhängigen Verformung können ZrO2 (TZP)-Federn, trotz ihrer hervorragenden Festigkeit und Bruchzähigkeit, nicht für die konzipierten Sensorfedern eingesetzt werden. - Das durch die Fa. Siegert TFT entwickelte Metallisierungs-Schichtsystem, bestehend aus aufgesputterten Ti-, Pt- und Au-Schichten verstärkt durch eine galvanisch aufgebrachte Au-Schicht, wurde an der BAM umfassend bewertet. Die Schichten sind untereinander und mit der Keramik weitgehend defektfrei verbunden, die lokale Schichtdicke schwankt jedoch bedingt durch Abschattungseffekte während der Beschichtungsvorgang. Es wurden Schichtwiderstände zwischen 50 und 90 Ohm und damit die Zielvorgabe des Projektes (< 100 Ohm) erreicht. In statischen und dynamischen Belastungstests wurden keine Veränderungen der Leitungswiderstände festgestellt. - Zur Erhöhung der Kapazität des Kondensators kann der Raum zwischen den Federwindungen statt mit Luft mit einer Flüssigkeit mit hoher Dielektrizitätskonstante gefüllt werden. Als geeignete Flüssigkeit wurde Propylencarbonat mit einer Dielektrizitätskonstante von 65, einem hohen Siedepunkt und einer geringen Viskosität identifiziert. Um eine noch höhere Dielektrizitätskonstante zwischen den Federwindungen zu erreichen. wurden Suspensionen aus Silikonöl und nanokristallinem Bariumtitanat hergestellt und bezüglich ihrer Langzeitstabiltät charakterisiert. - Gemäß den Anforderungen des Projektpartners KOMPASS wurden maßgeschneiderte Al2O3-Federn mit einer Federkonstante < 0,1 N/mm hergestellt und für den Aufbau des finalen Demonstrator eingesetzt. Die prinzipielle Funktionsfähigkeit des neuen Sensorkonzeptes auf Basis keramischer Federn wurde mit dem im Projekt aufgebauten Demonstrator nachgewiesen. Die Umsetzung der F+E-ergebnisse in eine industrielle Nutzung zur Herstellung von Gravimetern wird vom Projektpartner KOMPASS angestrebt und ist bereits mit detaillierten Zeitplänen untersetzt. KW - Langzeitstabilität KW - Sensorik KW - Keramikfeder KW - Spannungs-Dehnungs-Verhalten PY - 2019 UR - https://www.gbv.de/dms/tib-ub-hannover/1681417375.pdf UR - https://www.tib.eu/de/suchen/id/TIBKAT%3A1681417375/Alterungsbest%C3%A4ndige-keramische-Federsensoren-durch/ SP - 1 EP - 64 PB - Bundesanstalt für Materialforschung und -prüfung CY - Berlin AN - OPUS4-50742 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rabe, Torsten A1 - Schulz, Bärbel A1 - Paulick, C. A1 - Kalinka, Gerhard T1 - Helical zirconia (TZP) springs manufacturing and testing under mechanical and thermal load N2 - 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. T2 - German Ceramic Society, Annual Meeting 2018 CY - München, Germany DA - 09.04.2018 KW - Ceramic springs KW - Manufacturing KW - Mechanical and thermal testing PY - 2018 AN - OPUS4-44728 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rabe, Torsten A1 - Schulz, Bärbel A1 - Kalinka, Gerhard T1 - Deformation behavior of alumina and zirconia springs at room temperature N2 - 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. T2 - D-A-CH Keramiktagung CY - Leoben, Austria DA - 06.05.2019 KW - Phase transformation KW - Ceramic spring KW - Force-distance diagram KW - Deformation behavior PY - 2019 AN - OPUS4-48026 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rabe, T. A1 - Kalinka, Gerhard A1 - Mieller, Björn T1 - Manufacturing and deformation behavior of alumina and zirconia helical springs at room temperature N2 - 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. KW - Alumina KW - Creep KW - Elastic properties KW - Zirconia PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-571858 DO - https://doi.org/10.1111/jace.19085 SN - 0002-7820 SP - 1 EP - 14 PB - Wiley-Blackwell CY - Oxford [u.a.] AN - OPUS4-57185 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Qian, Hui A1 - Bismarck, A. A1 - Greenhalgh, E.S. A1 - Kalinka, Gerhard A1 - Shaffer, M.S.P. T1 - Hierarchical composites reinforced with carbon nanotube grafted fibers: The potential assessed at the single fiber level N2 - 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. KW - Composites KW - Nano tubes KW - Grafting KW - Interface PY - 2008 DO - https://doi.org/10.1021/cm702782j SN - 0897-4756 SN - 1520-5002 VL - 20 IS - 5 SP - 1862 EP - 1869 PB - American Chemical Society CY - Washington, DC AN - OPUS4-34568 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Qian, H. A1 - Kalinka, Gerhard A1 - Chan, K.L.A. A1 - Kazarian, S.G. A1 - Greenhalgh, E.S. A1 - Bismarck, A. A1 - Shaffer, M.S.P. T1 - Mapping local microstructure and mechanical performance around carbon nanotube grafted silica fibres: Methodologies for hierarchical composites N2 - 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. KW - Nanotubes KW - Silica fibres KW - Nano indentation KW - Mapping PY - 2011 DO - https://doi.org/10.1039/c1nr10497g SN - 2040-3364 SN - 2040-3372 VL - 3 IS - 11 SP - 4759 EP - 4767 PB - RSC Publ. CY - Cambridge AN - OPUS4-34718 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Qian, H. A1 - Bismarck, A. A1 - Greenhalgh, E. A1 - Kalinka, Gerhard A1 - Shaffer, M.S.P. T1 - Hierachical composites reinforced with carbon nanotube grafted fibres T2 - MC 8: ADVANCING MATERIALS BY CHEMICAL DESIGN CY - London, England DA - 2007-05-02 PY - 2007 AN - OPUS4-20121 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Prewitz, Marc T1 - Charakterisierung von Glas-Polymer Verbundmaterialien fur die Hochdruckspeicherung von Wasserstoff N2 - In der vorliegenden Arbeit werden Glaskapillaren und Strukturen aus Borosilikatglas (Simax) f¨ur die Hochdruckspeicherung von Wasserstoff betrachtet. Um die mechanischen Belastungen zu analysieren und anschließend ein optimiertes Speicherdesign abzuleiten, findet die Finite Element Methode (FEM) Einsatz. Die notwendigen Materialkennwerte werden zuvor experimentell ermittelt. Dazu geh¨oren die Festigkeit, die Schubfestigkeit der Grenzfl¨ache Klebung/Glas, der Wasserstoffpermeationskoeffizient, das Temperatur-Zeit-abh¨angige Verhalten, sowie die obere Temperatureinsatzgrenze. Die Glasfestigkeit ist stark abh¨angig von der Oberfl¨acheng¨ute. Daher werden in dieser Arbeit Kapillaren selber gezogen und beschichtet. Der Einfluss auf die Festigkeit wird mit Hilfe von Berstversuchen untersucht. Die eingesetzten Polymere werden zus¨atzlich mit dem Push-out Versuch, der dynamisch mechanischen Analyse und der Permeationsmessung charakterisiert. Dar¨uber hinaus wird aus den DMA Versuchen ein viskoelastisches Materialmodell abgeleitet, womit der Temperatur- und Zeiteinfluss auf die mechanische Belastung simuliert wird. Unter Beachtung der experimentell gewonnenen Erkenntnisse, sowie der durchgef¨uhrten Simulation ist es m¨oglich, ein optimiertes Speicherdesign zu erstellen und Aussagen ¨uber die Einsatzgrenzen zu treffen. KW - Wasserstoffspeicherung KW - Glaskapillaren KW - Polymercoating PY - 2017 UR - https://depositonce.tu-berlin.de/handle/11303/6261 SP - 1 EP - 150 CY - Berlin AN - OPUS4-51065 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pommet, M. A1 - Juntaro, J. A1 - Heng, J.Y.Y. A1 - Mantalaris, A. A1 - Lee, A.F. A1 - Wilson, K. A1 - Kalinka, Gerhard A1 - Shaffer, M.S.P. A1 - Bismarck, A. T1 - Surface modification of natural fibers using bacteria: depositing bacterial cellulose onto natural fibers to create hierarchical fiber reinforced nanocomposites N2 - 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. KW - Composires KW - Bacteria KW - Surface KW - Cellulose natural fibers PY - 2008 DO - https://doi.org/10.1021/bm800169g SN - 1525-7797 VL - 9 IS - 6 SP - 1643 EP - 1651 PB - ACS Publ. CY - Washington, DC, USA AN - OPUS4-23162 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Plichta, T. A1 - Sirjovona, V. A1 - Zvonek, M. A1 - Kalinka, Gerhard A1 - Cech, V. T1 - The Adhesion of Plasma Nanocoatings Controls the Shear Properties of GF/Polyester Composite N2 - 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. KW - Mechanical properties KW - Plasma nanocoatings KW - Glass fibre KW - Polymer composite KW - Short-beam strength KW - Interfacial shear strength KW - Work of adhesion PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521844 DO - https://doi.org/10.3390/polym13040593 VL - 13 IS - 4 SP - 593 PB - MDPI CY - Basel,Schweiz AN - OPUS4-52184 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pavasarytė, Lina A1 - Azevedo do Nascimento, Allana A1 - Cysne Barbosa, Ana Paula A1 - Trappe, Volker A1 - Melo, Daniel T1 - Effects of particle size and particle concentration of poly (ethylene-co-methacrylic acid) on properties of epoxy resin N2 - Self-healing polymers have been developed to improve durability and reduce costs associated with maintenance during service. The addition of thermoplastics to thermosets to produce mendable polymers appears as a promising selfhealing technique. In this study, poly (ethylene-co-methacrylic acid) (EMAA) was added to epoxy resin and the effects of EMAA addition on epoxy properties were evaluated. Specimens with two different contents of thermoplastic and particles sizes were manufactured. A two-level full factorial experimental design was used to evaluate the effect of particle size and particle content on properties of epoxy modified with addition of EMAA. Tensile tests and dynamic mechanical analysis (DMA) were used and the evaluated responses were tensile strength, modulus of elasticity, and glass transition temperature (Tg). X-ray computed tomography (XCT) was used to investigate particle size and concentration after manufacturing. It was found that the particle concentration has greater effects on stress–strain behavior of epoxy while Tg was not significantly affected by neither of the analyzed entrance variables. KW - Fracture KW - Self-healing KW - Epoxy KW - Thermoplastic PY - 2024 DO - https://doi.org/10.1002/app.55677 SN - 0021-8995 SP - 1 EP - 14 PB - Wiley online library AN - OPUS4-60205 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Palantöken, Sinam A1 - Bethke, K. A1 - Zivanovic, V. A1 - Kneipp, Janina A1 - Rademann, Klaus A1 - Kalinka, Gerhard T1 - Cellulose hydrogels physically crosslinked by glycine: Synthesis, characterization, thermal and mechanical properties N2 - 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. KW - Biopolymer KW - Cellulose KW - Hydrogel KW - Natural KW - Synthesis PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486845 DO - https://doi.org/10.1002/APP.48380 SN - 1097-4628 SN - 0021-8995 VL - 136 SP - 48380, 1 EP - 11 PB - Wiley CY - USA AN - OPUS4-48684 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nowak, H. A1 - Kalinka, Gerhard A1 - Hinrichsen, G. T1 - Investigations on the cold crystallization of pure and filled PETP by dielectric measurements N2 - 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. KW - Verbundwerkstoffe KW - Gefüllte Kunststoffe KW - Elektrische Eigenschaften KW - Verlustfaktor KW - Dielektrische Analyse PY - 1993 SN - 0323-7648 SN - 1521-4044 VL - 44 IS - 1 SP - 25 EP - 28 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-11995 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Munz, Martin A1 - Chung, Jae Un A1 - Kalinka, Gerhard ED - Possart, W. T1 - Mapping Epoxy Interphases T2 - 7th European Conference on Adhesion ; 7th EURADH CY - Freiberg, Germany DA - 2004-09-01 KW - Interface KW - Interphase KW - Epoxy KW - Copper (Cu) KW - Polyvinylpyrrolidone (PVP) KW - AFM/SFM KW - DSI KW - EDX/EDS KW - Stiffness KW - Modulus KW - Interdiffusion PY - 2005 SN - 3-527-31263-3 VL - 7 SP - 103 EP - 123 PB - Wiley-VCH CY - Weinheim AN - OPUS4-10894 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Munz, Martin A1 - Sturm, Heinz A1 - Kalinka, Gerhard T1 - On the stiffness gradient at the interface between an amine-cured epoxy and a thermoplast T2 - 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) CY - Erlangen, Germany DA - 2005-02-17 PY - 2005 AN - OPUS4-7137 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn T1 - Herstellung und Charakterisierung keramischer Federn N2 - Aufgrund ihres spezifischen Eigenschaftsprofils sind keramische Federn attraktiv für Spezialanwendungen in Maschinenanlagen, Metrologie und Sensortechnik. Durch Hartbearbeitung keramischer Hohlzylinder können Spiralfedern mit rechteckigem Windungsquerschnitt präzise gefertigt werden. Dabei kann durch gezielte Auslegung der Federgeometrie die Federkonstante über mehrere Größenordnungen variiert werden. Der Vortrag gibt einen Überblick über den Herstellungsprozess, verschiedene Eigenschaften keramischer Federn und Anwendungsbeispiele. T2 - Industrieller Arbeitskreis Keramikbearbeitung CY - Online meeting DA - 08.04.2022 KW - Keramik KW - Hartbearbeitung KW - Federkonstante PY - 2022 AN - OPUS4-54623 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Michaeli, W. A1 - Baranowski, T. A1 - Kalinka, Gerhard T1 - Einfluss der Mikrostruktur auf den Druck- und Zug-E-Modul teilkristalliner Kunststoffe N2 - In Kooperation zwischen dem Institut für Kunststoffverarbeitung (IKV) und der Bundesanstalt für Materialforschung und -prüfung (BAM) wurde das mechanische Verhalten unter Druck- und Zugbelastung unterschiedlicher morphologischer Strukturen teilkristalliner Thermoplaste (PP und POM) untersucht. Im Ergebnis steigt der E-Modul sowohl der druck- wie auch zugbelasteten Prüfkörper aus spritzgegossenem PP und POM mit gröberem Gefüge an. Probekörper mit scherinduziertem Gefüge zeigen einen hohen Einfluss des Kristallisationsgrads auf den E-Modul. KW - Carbon fibre KW - Nanotubes KW - Hierarchical composites KW - Pull-out test KW - Push-out test PY - 2011 SN - 0025-5300 VL - 53 IS - 10 SP - 616 EP - 628 PB - Hanser CY - München AN - OPUS4-24341 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meretz, S. A1 - Lahser, K. A1 - Lehmann, V. A1 - Kalinka, Gerhard A1 - Hampe, Andreas T1 - Kristallisationskinetik bei Faserverbundwerkstoffen T2 - Kolloquium der Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin, Germany DA - 1993-10-01 PY - 1993 AN - OPUS4-12128 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -