TY - JOUR A1 - Rabe, Torsten A1 - Eberlee, Ina A1 - Güther, Wolfgang A1 - Stark, Wolfgang T1 - Mechanische und thermomechanische Charakterisierung keramischer Grünfolien KW - Keramische Grünfolien KW - Mechanische Prüfung KW - DMTA PY - 2004 SN - 0173-9913 SN - 0196-6219 VL - 18 IS - 1 SP - 58 EP - 68 PB - Göller CY - Baden-Baden AN - OPUS4-5338 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Buchholz, Uwe A1 - Jaunich, Matthias A1 - Stark, Wolfgang A1 - Habel, Wolfgang A1 - Petersson, B.A.T. T1 - Acoustic data of cross linked polyethylene (XLPE) and cured liquid silicone rubber (LSR) by means of ultrasonic and low frequency DMTA N2 - Partial discharges may cause damage to electrical insulation of high voltage equipment. They initiate elastic waves in the insulating material, e.g. in the stress cone of an outdoor termination. Localisation of the origin of such elastic waves can help to predict serious damaging processes in the electrical insulation. In order to measure and evaluate the wave propagation effects in typical multilayered elastomeric structures, knowledge of the material properties is required. The propagating velocity and the attenuation of longitudinal waves are important parameters. Values for these quantities found in the literature were not appropriate. Therefore, for cross-linked polyethylene (XLPE) and cured liquid silicone rubber (LSR), the longitudinal wave velocity and the attenuation were evaluated in the temperature interval from -20°C to 50°C and in the frequency range from 200 kHz to 600 kHz using a two-sample ultrasound technique. The loss factor was determined from these measured quantities. Additionally, low frequency Dynamic Mechanical Thermal Analysis (DMTA) was applied to investigate LSR and XLPE in a temperature interval between -100 and 50°C and to check qualitatively the ultrasound data. KW - Acoustic propagation KW - Cross linked polyethylene insulation KW - Mechanical variables measurement KW - Silicone rubber PY - 2012 DO - https://doi.org/10.1109/TDEI.2012.6180250 SN - 1070-9878 SN - 0018-9367 SN - 1558-4135 VL - 19 IS - 2 SP - 558 EP - 566 PB - Institute of Electrical and Electronics Engineers CY - New York, NY AN - OPUS4-26106 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böhning, Martin A1 - Niebergall, Ute A1 - Adam, Adeline A1 - Stark, Wolfgang T1 - Impact of biodiesel sorption on mechanical properties of polyethylene N2 - The time-dependent sorption of biodiesel in a typical polyethylene for container applications is investigated in comparison to conventional diesel fuel at three different temperatures. In this context, the desorption behavior is also addressed. Subsequently, the effects of both penetrants on mechanical properties are characterized in terms of impact strength and dynamic-mechanical analysis. The discussion of property changes is firstly based on the sorption kinetics of biodiesel and diesel, which is determined by immersion experiments allowing for the calculation of respective diffusion coefficients. Changes in impact strength as determined by the Charpy method are further characterised in more detail by analyzing the fracture surfaces, and correlated with results of dynamic-mechanical analysis. KW - Biodiesel KW - Fuel sorption KW - Desorption KW - Impact strength KW - Dynamic-mechanical analysis KW - PE-HD PY - 2014 DO - https://doi.org/10.1016/j.polymertesting.2013.12.003 SN - 0142-9418 VL - 34 SP - 17 EP - 24 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-30096 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gaal, Mate A1 - Bovtun, Viktor A1 - Stark, Wolfgang A1 - Erhard, Anton A1 - Yakymenko, Y. A1 - Kreutzbruck, Marc T1 - Viscoelastic properties of cellular polypropylene ferroelectrets N2 - Viscoelastic properties of cellular polypropylene ferroelectrets (PP FEs) were studied at low frequencies (0.3–33 Hz) by dynamic mechanical analysis and at high frequencies (250 kHz) by laser Doppler vibrometry. Relaxation behavior of the in-plane Young’s modulus (Y´ 11~1500 MPa at room temperature) was observed and attributed to the viscoelastic response of polypropylene matrix. The out-of-plane Young’s modulus is very small (Y´33≈0.1 MPa) at low frequencies, frequency- and stress-dependent, evidencing nonlinear viscoelastic response of PP FEs. The highfrequency mechanical response of PP FEs is shown to be linear viscoelastic with Y´33≈0.8 MPa. It is described by thickness vibration mode and modeled as a damped harmonic oscillator with one degree of freedom. Frequency dependence of Y*33 in the large dynamic strain regime is described by the broad Cole-Cole relaxation with a mean frequency in kHz range attributed to the Dynamics of the air flow between partially closed air-filled voids in PP FEs. Switching-off the relaxation contribution causes dynamic crossover from the nonlinear viscoelastic regime at low frequencies to the linear viscoelastic regime at high frequencies. In the small strain regime, contribution of the air flow seems to be insignificant and the power-law response, attributed to the mechanics of polypropylene cell walls and closed air voids, dominates in a broad frequency range. Mechanical Relaxation caused by the air flow mechanism takes place in the sound and ultrasound frequency range (10 Hz–1MHz) and, therefore, should be taken into account in ultrasonic applications of the PP FEs deal with strong exciting or receiving signals. KW - Viscoelastic KW - Cellular polypropylene KW - Ferroelectret PY - 2016 DO - https://doi.org/10.1063/1.4944798 SN - 0021-8979 SN - 1089-7550 SN - 1520-8850 VL - 119 SP - Article Number: 125101 PB - AIP Publishing AN - OPUS4-35956 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Braun, Ulrike A1 - Brademann-Jock, Kerstin A1 - Stark, Wolfgang T1 - Cure monitoring of epoxy films by heatable in situ FTIR analysis: Correlation to composite parts N2 - The curing mechanism of an epoxy film containing dicyandiamide (DICY) and an epoxy formulation based on diglycidyl ether of Bisphenol A (DGEBA) polymer was studied as a function of various temperature programs. The investigation was performed in situ, using a thin film of the epoxy mixture on a silicon wafer substrate in a heatable transmission tool of a FTIR spectrometer. Based on these model-curing experiments, a major curing mechanism was proposed, taking into account the appearance, the decrease, and the development of characteristic bands at various temperatures. The conclusions of the model curing were correlated to FTIR measurements on a real, 50-mm-thick glass fiber reinforced component composite part from a technical process. It could be shown that characteristic bands that develop at curing temperatures above 150°C appear especially in the center of the thick sample. From the chemical or molecular point of view, this demonstrates the established technician's understanding that temperature control inside a large-scale fiber composite of, for example, aircraft, wind-turbine, automotive applications component is of major importance. KW - Crosslinking KW - Resins KW - Spectroscopy KW - Thermosets KW - Thermal properties PY - 2014 DO - https://doi.org/10.1002/APP.39832 SN - 0021-8995 SN - 1097-4628 VL - 131 IS - 3 SP - 39832, 1 EP - 10 PB - Wiley InterScience CY - Hoboken, NJ AN - OPUS4-30716 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gaal, Mate A1 - Bovtun, V. A1 - Stark, Wolfgang A1 - Kreutzbruck, Marc ED - Kollmeier, B. T1 - Bestimmung der elastischen Eigenschaften des Polypropylen-Ferroelektrets N2 - Ferroelektrete sind zelluläre polarisierte Polymere, die ferroelektrische und dadurch auch piezoelektrische Eigenschaften aufweisen. Unter anderem werden sie für den Bau von Mikrofonen und Ultraschallwandlern für Materialprüfung eingesetzt. Dabei erweist sich ihre besonders niedrige akustische Impedanz als Vorteil. Ursache dafür ist vor allem ihr außergewöhnlich niedriger Elastizitätsmodul in Dickenrichtung. In diesem Beitrag werden zwei Methoden für die Ermittlung des Elastizitätsmoduls des geladenen zellulären Polypropylens (zPP) dargestellt. Die erste ist eine neuartige modellgestützte Methode mittels Laservibrometrie an dem eigenentwickelten Polypropylen-Wandler, wobei die Resonanzschwingung des Wandlers bei 250 kHz gemessen wird. Die zweite Methode ist dynamisch-mechanische Analyse (DMA) durchgeführt mit Frequenzen von 0,3 bis 50 Hz, erstmalig für das zPP angewendet. T2 - DAGA 2014 - 40. Jahrestagung für Akustik CY - Oldenburg, Germany DA - 10.03.2014 PY - 2014 SN - 978-3-939296-06-5 SP - 1 EP - 2 AN - OPUS4-31368 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - McHugh, Jarlath A1 - Stark, Wolfgang T1 - Determination and interpretation of changes in thermophysical properties of a carbon-fibre prepreg during cure N2 - Epoxy composites used for high-end structural applications are typically cured under the influence of temperature and pressure causing a number of complex chemical and physical transformations. On heating a mould, temperature gradients will occur through the component which will depend largely on the thermophysical properties of the specific composite. The crosslinking reaction is exothermic leading to additional heat release, thus complicating heat transportation models. If such effects are not accounted for, it can lead to variations in resin flow, poor fibre wetting causing voiding and inhomogeneous cure, leading to shrinkage and unfavourable variations in moulded part geometry. Limited information is available for thermal models used in the manufacture of reinforced thermosets. Autoclave [1, 2] and laser or infra-red curing processes [3, 4] typically use constant values determined on fully cured parts. In this work, the variation in thermal conductivity (K) (W/(m K)), thermal diffusivity (a) (m(2)/s) and specific heat capacity at constant pressure (c(p)) (J/(g K) is determined for a carbon fibre prepreg during cure. It is the intention to improve understanding of how these parameters are related to chemical or physical transformations occurring during cure, and where estimates or shortcuts may be used for heat transfer models KW - Differential scanning calorimetry KW - Temerature KW - Epoxy system PY - 2016 DO - https://doi.org/10.1016/j.polymertesting.2015.11.015 SN - 0142-9418 VL - 49 SP - 115 EP - 120 PB - Elsevier Science CY - Oxford AN - OPUS4-35788 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Characterizing the flow-cure behaviour of thermoset plastics using thermoanalytical and ultrasonic methods N2 - The prospects of modern thermoanalytical methods for characterisation of flow, curing and final mechanical behaviour of moulding compounds were demonstrated. Using urea resin moulding compounds from different manufacturers the possibilities of the various techniques could be shown. With comparatively low effort, fundamental information can be gained before production process had been started. On this basis it is possible to make appropriate material selection at an early point in the process chain. On the basis of thermoanalytical data an incoming goods inspection can be established. Also it is easy to control the compliance with the conditions of delivery. In some cases it could also be helpful to have stored analysis data especially when problems appear in manufacturing process or unexpected part damages occur With the ultrasound measuring system it is possible to transfer the findings from the analytical methods directly to the processes in the mould. The application of ultrasound provides Dynamic Mechanical Analysis in the mould. Beside quality assurance ultrasound can also be used for process optimisation, especially for reduction of cycle time. In an advanced form ultrasound information can be used as a basis for improved machine control based on material state. The ultrasound measuring system developed by ISK Iserlohn and BAM can be obtained from the ISK. T2 - 5. Internationale Duroplasttagung / International Thermoset Conference CY - Iserlohn, Germany DA - 2008-11-20 KW - Differential Scanning Calorimetry KW - Dynamic Mechanical Analysis KW - Ultrasound KW - Urea rsin KW - Moulding compound KW - Incoming goods inspection KW - Process optimization PY - 2008 IS - Duro08_GB_08 SP - 1 EP - 8 AN - OPUS4-18586 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang A1 - Bartusch, Jürgen A1 - Döring, Joachim A1 - Mc Hugh, Jarlath T1 - Making cure visible: monitoring the crosslinking process using integrated ultrasound sensors N2 - A special ultrasonic measuring system was developed to monitor the cross-linking process, enabling interaction with the manufacturing process in order to optimise part quality and reduce cycle times. KW - Thermoset KW - Ultrasound sensors KW - Mould KW - Rtm KW - Gelation KW - Vitrification PY - 2008 SN - 1639-965X IS - 38 SP - 64 EP - 66 PB - JEC CY - Paris AN - OPUS4-18610 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang A1 - Kürten, C. T1 - Verarbeitung von Harnstoff-Formmassen - Begleitende Online-Prozesskontrolle N2 - Harnstoff-Formmassen gehören zu den duroplastischen Formmassen, die im Werkzeug chemisch vernetzen und so ihre herausragende Temperaturbeständigkeit erreichen. Im Wettbewerb mit Thermoplasten weisen Formmassen den Nachteil auf, dass die Vernetzungsreaktion eine kritische Zeit bedingt, damit die Glasübergangstemperatur soweit verschoben werden kann, dass die heißen Teile stabil und blasenfrei entformt werden können. Die Zykluszeiten sind bei Formmassen daher deutlich höher als bei Thermoplasten. Eine Möglichkeit, die Zykluszeit zu verringern, wäre die Erhöhung der Werkzeugtemperatur, da bekanntlich eine Erhöhung der Reaktionstemperatur um 10 K zu einer Verdoppelung der Reaktionsgeschwindigkeit führt. Allerdings wird dabei das Zeitfenster für die Entformung optimal gehärteter Teile deutlich kleiner, der Prozess anfälliger gegen Schwankungen im Prozess und in der Formmasse-Zusammensetzung. Mit einer Online-Kontrolle des Vernetzungszustands sollte es aber gelingen, den Prozess auch bei einer höheren Werkzeugtemperatur noch stabil zu beherrschen. In der vorliegenden Arbeit wird die Methode der dielektrischen Prozesskontrolle in der Fertigung von Spritzgieß-Formteilen erprobt und die Möglichkeiten einer Prozesssteuerung werden herausgearbeitet. KW - Harnstoffharz KW - Elektroinstallationsteile KW - Aushärtungsverlauf KW - Kochversuch PY - 2008 SN - 0176-1625 VL - 61 IS - 12 SP - 790 EP - 793 PB - Gupta CY - Ratingen AN - OPUS4-18734 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang A1 - Goering, Harald A1 - Michel, U. A1 - Bayerl, H. T1 - Online monitoring of thermoset post-curing by dynamic mechanical thermal analysis DMTA N2 - Thermosetting moulding compounds are synthetic materials which can be easily formed in the molten state and achieve high temperature stability due to a cross-linking process which takes place during manufacture. To ensure thermal and mechanical properties, post-curing of moulded phenolic resin components is necessary for high quality applications. In the industrial practice, post-curing time-temperature-programs are heuristically acquired. In this paper, dynamical mechanical thermal analysis is employed to determine optimal post-curing conditions for injection moulded parts from phenolic resin. KW - DMTA KW - Moulding compound KW - Thermoset KW - Phenolic resin KW - Post-curing PY - 2009 DO - https://doi.org/10.1016/j.polymertesting.2009.02.005 SN - 0142-9418 VL - 28 IS - 6 SP - 561 EP - 566 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-19822 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Das Referenzelastomerprogramm der BAM T2 - Frühjahrstreffen der Bezirksgruppe Ost der Deutschen Kautschuk-Gesellschaft CY - Berlin, Germany DA - 2010-05-27 PY - 2010 AN - OPUS4-21393 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Döring, Joachim A1 - Stark, Wolfgang T1 - Untersuchungen zur Aushärtung von Duroplasten T2 - DACH-Tagung 1996 CY - Lindau, Deutschland DA - 1996-05-13 PY - 1996 SN - 3-931381-07-0 VL - 52 SP - 765 EP - 771 AN - OPUS4-22935 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Döring, Joachim A1 - Stark, Wolfgang A1 - Mc Hugh, Jarlath A1 - Bartusch, Jürgen T1 - Erfassung des Fließ-Härtungs-Verhaltens von Duromeren mit Ultraschall N2 - Das Fließ-Härtungs-Verhalten von Duroplastformmassen wird gegenwärtig nur unvollständig durch empirische Größen beschrieben. Diese ungenauen und unsicheren Angaben können zu Schwierigkeiten bei der optimalen Einstellung der Fertigungsmaschinen des Verarbeiters führen. Insbesondere Veränderungen der Formmasseeigenschaften während des Transportes und der Lagerung stören die Produktion. Das vorgestellte Messverfahren mit Ultraschall-sensoren ermöglicht die schnelle und vollständige Erfassung des Fließ-Härtungs-Verhaltens, auch während des technologischen Prozesses. Experimentelle Ergebnisse zu Alterungs-erscheinungen dieser Formmassen illustrieren den Nutzen des Verfahrens für Formmasse-produzenten und -verarbeiter. T2 - DGZfP-Jahrestagung 1999 CY - Celle, Deutschland DA - 1999-05-10 PY - 1999 SN - 3-931381-27-7 IS - DGZfP-BB 68 SP - 221 EP - 228 AN - OPUS4-22937 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Simulation of cross-linking process of prepregs by dynamic mechanical analysis T2 - 11. Internationale Tagung "Arbeitsgemeinschaft verstärkte Kunststoffe AVK" CY - Essen, Germany DA - 2008-09-22 PY - 2008 AN - OPUS4-17946 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang A1 - Döring, Joachim A1 - Kürten, C. T1 - Vernetzung reaktiver Kunststoffe mit Ultraschall überwachen KW - Elastomer KW - Epoxidharz KW - Phenolharz KW - Vernetzung KW - Vulkanisation KW - Schallgeschwindgkeit KW - Prozesskontrolle PY - 2008 SN - 0939-2629 SN - 0176-6058 IS - 2 SP - 31 EP - 33 PB - Holzverl. CY - Kissing AN - OPUS4-17587 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Change of specific heat; thermal diffusity and thermal conductivity of a c-fibre prepreg during curing T2 - 15. Nationales Symposium SAMPE Deutschland CY - Berlin, Germany DA - 2009-02-18 PY - 2009 AN - OPUS4-18972 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Investigation of epoxy curing and determination of glass transition temperature by dynamic mechanical analysis (DMA) T2 - 15. Nationales Symposium SAMPE Deutschland CY - Berlin, Germany DA - 2009-02-18 PY - 2009 AN - OPUS4-18973 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Stark, Wolfgang T1 - Historische Entwicklung der Überwachungsmethoden bei der Duroplastverarbeitung T2 - TECHNOMER 2009 - 21. Fachtagung über Verarbeitung und Anwendung von Polymeren CY - Chemnitz, Deutschland DA - 2009-11-12 KW - Bakelit KW - Phenolharz KW - Isolierstoff KW - Gütesicherung KW - Prüfung PY - 2009 SN - 978-3-939382-09-6 IS - PQP4 SP - 1 EP - 9 AN - OPUS4-20399 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang T1 - Entwicklung der Gütesicherung bei Isolierstoffen KW - Materialprüfungsamt KW - Kunstharze KW - Bakelit KW - Phenolharz KW - Aminoharz KW - Gütesicherung KW - Technische Vereinigung PY - 2010 UR - https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwivis-l7tvKAhVFWBoKHa-jD1gQFggeMAA&url=https%3A%2F%2Fwww.kunststoffe.de%2F_storage%2Fasset%2F538701%2Fstorage%2Fmaster%2Ffile%2F5804889%2Fdownload%2FEntwicklung%2520der%2520G%25C3%25BCtesicherung%2520bei%2520Isolierstoffen.pdf&usg=AFQjCNE14vu5Aw1foQ7OZdcTT2vwsRX_TQ SN - 0023-5563 VL - 100 IS - 2 SP - 14 EP - 17 PB - Hanser CY - München AN - OPUS4-20935 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang T1 - Development of quality assurance for insulating materials PY - 2010 UR - https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwjyyejZ7tvKAhXBVxoKHeV0Dr4QFgghMAA&url=https%3A%2F%2Fwww.kunststoffe.de%2Fen%2F_storage%2Fasset%2F590842%2Fstorage%2Fmaster%2Ffile%2F6128237%2Fdownload%2FDevelopment%2520of%2520Quality%2520Assurance%2520for%2520Insulating%2520Materials.pdf&usg=AFQjCNGMbKTaYDrHEdGuZ2IB_7zQCrTVkw SN - 1862-4243 VL - 100 IS - 2 SP - 6 EP - 9 PB - Hanser CY - München AN - OPUS4-20936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang T1 - Investigation of curing behaviour of melamine/phenolic (MP) thermosets N2 - Commercially available melamine/phenolic (MP) moulding compounds used for manufacturing electro installation parts were investigated by laboratory thermal analysis methods: Dynamic Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC) and Dielectric Analysis (DEA). The results were compared with on-line measurements in a compression mould using incorporated dielectric and ultrasound sensors. Softening and cross-linking behaviour were analyzed. For on-line process monitoring, only the ultrasound method worked well. The dielectric method was distorted by water formed as a by-product from the poly-condensation reaction. KW - Thermoset KW - Melamine KW - Phenol KW - Moulding compound KW - Cross-linking KW - DSC PY - 2010 DO - https://doi.org/10.1016/j.polymertesting.2010.05.008 SN - 0142-9418 VL - 29 IS - 6 SP - 723 EP - 728 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-20982 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Kontrolle des Vernetzungsverhaltens von reaktiven Kunststoffen T2 - 2. Wildauer Duromer-Tagung CY - Wildau, Germany DA - 2010-03-11 PY - 2010 AN - OPUS4-21011 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Kontrolle der Härtung bei reaktiven Formmassen und Faserverbundbauteilen T2 - 2. Wildauer Duromer-Tagung CY - Wildau, Germany DA - 2010-03-11 PY - 2010 AN - OPUS4-21015 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Die Rolle des Staatlichen Materialprüfungsamtes Berlin-Dahlem bei der Typisierung der Pressmassen und der Gütesicherung T2 - 6th International Thermoset Conference CY - Iserlohn, Germany DA - 2011-03-23 PY - 2011 AN - OPUS4-23412 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Characterisation of Flow and Curing Behaviour of Thermosetting Materials by Thermoanalytical and Ultrasound Methods T2 - 5th International Thermoset Conference Iserlohn CY - Iserlohn, Germany DA - 2008-11-21 PY - 2008 AN - OPUS4-18428 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Ultraschallmesstechnik zur Wareneingangskontrolle und zur Überwachung T2 - 5th Int. Thermoset Conference CY - Iserlohn, Germany DA - 2008-11-20 PY - 2008 AN - OPUS4-18468 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Elastomere Referenzmaterialien und ausgewählte Prüfverfahren T2 - DVM-Tag 2009 Elastomere CY - Berlin, Germany DA - 2009-04-22 PY - 2009 AN - OPUS4-19291 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Kontrolle der Härtungsreaktion bei Faserverbundbauteilen T2 - 10. Schwarzheider Kunststoffkolloquium CY - Schwarzheide, Germany DA - 2010-09-08 PY - 2010 AN - OPUS4-21930 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mc Hugh, Jarlath A1 - Fideu, P. A1 - Herrmann, A. A1 - Stark, Wolfgang T1 - Determination and review of specific heat capacity measurements during isothermal cure of an epoxy using TM-DSC and standard DSC techniques N2 - The technique normally used to measure Cp during isothermal cure is Temperature Modulated - Dynamic Scanning Calorimetry TM-DSC. It is however not standardised, experimentally complicated and quite time intensive. As will be shown, Cp may also be estimated during isothermal cure just from using dynamic heating experiments on a fully cured sample. Such values are often sufficient for isothermal heat transfer models that otherwise employ a constant Cp value obtained from the fully cured epoxy. Secondly, the results from dynamic heating experiments provide a quick means, in comparison to isothermal TMDSC measurements, of estimating Cp variation during cure as well as providing a good estimate value for Cp towards the end of isothermal cure. As will be shown, such values obtained from a standardised measurement procedure are very helpful in setting up TMDSC experiments that are more sensitive to experimental error influenced by factors such as sample weight and geometry. The DSC results illustrate that the measured heat capacity Cp for a fully cured epoxy over a temperature range are very similar to values for samples partially cured at corresponding isothermal temperatures, under the prerequisite that vitrification takes place. In such cases the primary influence on Cp is specific measurement temperature and not degree of cure. For isothermal cure temperatures investigated between 150 and 200 °C, the total change of Cp during cure is nearly constant and correlates well with values published by authors on other epoxy based systems. Taking Cp variation as constant, it is possible from just dynamic heating experiments on the cured epoxy to estimate Cp for the uncured epoxy system at specific cure temperatures. The next step would be to estimate the full Cp profile during isothermal cure, however, in such cases, the time to vitrification would also be needed as additional information. PY - 2010 DO - https://doi.org/10.1016/j.polymertesting.2010.04.004 SN - 0142-9418 VL - 29 IS - 6 SP - 759 EP - 765 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-21916 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Charakterisierung des Aushärtungsverhaltens von vernetzenden Kunststoffen - vom Labor in die Fertigung T2 - Vortragsveranstaltung Fraunhofer Institut für angewandte Polymerforschung (IAP) CY - Potsdam, Germany DA - 2010-10-08 PY - 2010 AN - OPUS4-22114 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Ultrasound measuring system for flow front and cure monitoring at composite manufacturing (RTM, prepreg, injection moulding) T2 - Composite Europe, 5. Europäische Fachmesse und Forum für Verbundstoffe, Technologie und Anwendungen CY - Essen, Germany DA - 2010-09-14 PY - 2010 AN - OPUS4-22102 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schulze, Dietmar A1 - Fengler, Petra A1 - Stark, Wolfgang T1 - Die Ermittlung von Ozonkonzentrationen bei der Prüfung der Ozonbeständigkeit von Elastomeren N2 - Dargestellt wird eine Gegenüberstellung der Ergebnisse von Messungen zur Ozonkonzentrationsbestimmung nach zwei Verfahren. International wird in der Kautschukindustrie ein UV-spektroskopisches Verfahren angewandt. Die deutsche Kautschukindustrie verwendet ein nasschemisches Verfahren. Die beiden Verfahren ergeben nicht die gleichen Ergebnisse. Daher wird der Unterschied genauer ermittelt. Die Auswirkungen der unterschiedlichen Ozonkonzentrationsbestimmungen auf die Prüfung der Ozonbeständigkeit an Elastomeren werden gezeigt. KW - Ozonkonzentrationsbestimmung KW - UV-Spektroskopie KW - Nasschemische Analyse KW - Ozonbeständigkeit KW - Elastomere PY - 2011 SN - 0948-3276 SN - 0022-9520 VL - 05 SP - 15 EP - 19 PB - Hüthig CY - Heidelberg AN - OPUS4-23832 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang A1 - Döring, Joachim A1 - Goering, Harald A1 - Knappe, S. A1 - Mc Hugh, Jarlath A1 - Opfermann, J. T1 - Der RTM-Prozess und die Probleme von Gelierung, Verglasung und Aushärtegrad T2 - 6. Internationale AVK-TV Tagung für Verstärkte Kunststoffe und Duroplastische Formmassen ; 6th International AVK-TV Conference for Reinforced Plastics and Thermoset Moulding Compounds CY - Baden-Baden, Deutschland DA - 2003-10-07 KW - Epxidharz KW - Compositbauteil KW - Vernetzungsreaktion PY - 2003 VL - 6 SP - C14-1-C14-16 PB - AVK-TV CY - Frankfurt am Main AN - OPUS4-3034 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Dielektrische Online-Prozesskontrolle bei Formmassen T2 - Dielektrik-Seminar und Workshop der Fa. Netzsch CY - Selb, Germany DA - 2003-03-19 PY - 2003 AN - OPUS4-3227 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fengler, Petra A1 - Stark, Wolfgang A1 - Döring, Joachim A1 - Mc Hugh, Jarlath T1 - Coupling of hidden ultrasound sensors to a moulding tool N2 - Ultrasound on-line NDT methods have been demonstrated as a useful tool for monitoring the curing reaction of thermosets. In order to achieve this ultrasound sensors are incorporated into compression, injection and RTM (resin transfer) mould. For many commercial products imprints or any surface markings upon the moulded product are undesirable. Due to its physical properties ultrasound has a large advantage over other techniques for similar applications. The sound wave can pass through the wall of the mould and direct contact with the moulded part is not required. In this particular case one fundamental problem is a good coupling of the sensors to the mould wall. Several mediums came into question but because of the high technical (e. g. temperature and long time stability) and practical demands, it was decided that dry (non-fluid) coupling would be the most promising candidate. A handful of coupling foils suitable also at high temperatures and for long time application under industrial conditions were tested and are presented in this paper. KW - Sensors KW - Ultrasound KW - Mould wall coupling KW - Thermoset manufacturing PY - 2004 UR - http://www.ndt.net/article/v09n03/stark/stark.htm SN - 1435-4934 VL - 9 IS - 3 SP - 1 EP - 10 PB - NDT.net CY - Kirchwald AN - OPUS4-3316 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Der RTM-Prezess und die Probleme von Gelierung, Verglasung und Aushärtegrad T2 - Jahrestagung des AVK-TV 2003 CY - Baden-Baden, Germany DA - 2003-10-06 PY - 2003 AN - OPUS4-4555 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Charakterisierung duroplastischer Formmassen mit thermoanalytischen Methoden T2 - Frühjahrstagung des Fachverbandes Polymerphysik der Deutschen Physikalischen Gesellschaft (DPG) und Rheologentagung CY - Leipzig, Germany DA - 1999-03-01 PY - 1999 AN - OPUS4-5748 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bovtun, Viktor Petrovic A1 - Stark, Wolfgang A1 - Kelm, Jürgen A1 - Pashkov, V.M. A1 - Yakimenko, Y. T1 - Characterization of carbon black filled rubber compounds by the Microwave Coaxial Method KW - Dielectric parameters KW - Microwave methods KW - Filled rubber compounds KW - Vulcanisation PY - 2005 SN - 0025-5300 VL - 47 IS - 3 SP - 118 EP - 122 PB - Carl Hanser Verlag CY - München AN - OPUS4-7273 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mc Hugh, Jarlath A1 - Döring, Joachim A1 - Bartusch, Jürgen A1 - Stark, Wolfgang T1 - Making Cure Visible T2 - Aerospace Testing Expo 2005 - Europe, April 5-7, 2005, Hamburg CY - Hamburg, Deutschland DA - 2005-04-05 PY - 2005 SP - 4 pages PB - UKIP Media & Events CY - Dorking AN - OPUS4-7379 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Simone A1 - Goering, Harald A1 - Stark, Wolfgang A1 - Bayerl, H. A1 - Brinkmann, P. T1 - Thermoanalytische Untersuchungen zur Phenolharzhärtung unter hohem Druck - Ein Weg zur Optimierung der Nachtemperung T2 - 3rd International Thermoset Conference CY - Iserlohn, Deutschland DA - 2005-04-21 KW - Post curing KW - High pressure DSC KW - DMA KW - Reaction kinetic KW - Phenolic resin PY - 2005 SP - 107 EP - 114 PB - Fachhochschule Südwestfalen - Hochschule für Technik und Wirtschaft CY - Iserlohn AN - OPUS4-7452 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Simone A1 - Goering, Harald A1 - Stark, Wolfgang A1 - Bayerl, H. A1 - Brinkmann, P. T1 - Thermo Analytical Investigations of Phenol Moulding Compound Curing - Potential for Post-Cure Optimisation T2 - 3rd International Thermoset Conference CY - Iserlohn, Germany DA - 2005-04-21 KW - Post curing KW - High pressure DSC KW - DMA KW - Reaction kinetic KW - Phenolic resin PY - 2005 SP - 219 EP - 225 PB - Fachhochschule Südwestfalen - Hochschule für Technik und Wirtschaft CY - Iserlohn AN - OPUS4-7453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Formmassen: Ultraschall zur Warenausgangs- und Wareneingangskontrolle T2 - 3rd International Thermoset Conference CY - Iserlohn, Germany DA - 2005-04-21 PY - 2005 AN - OPUS4-7352 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - "Sehende" Nachtemperung: Praktische Anwendung der Methode der Dynamisch Mechanischen Analyse (DMA) T2 - 3rd International Thermoset Conference CY - Iserlohn, Germany DA - 2005-04-21 PY - 2005 AN - OPUS4-7353 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Straet, T. A1 - Bayerl, H. A1 - Stark, Wolfgang A1 - Döring, Joachim A1 - Kürten, Ch. T1 - Ultrasonic Measurements on Thermoset Moulding Compounds KW - Ultraschall KW - Fertigungskontrolle KW - Schallgeschwindigkeit KW - Vernetzungsreaktion KW - Qualitätssicherung PY - 2005 SN - 0945-0084 VL - 95 IS - 7 SP - 1 EP - 5 PB - Hanser CY - München AN - OPUS4-10304 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Döring, Joachim A1 - Stark, Wolfgang T1 - Ultrasonic Production Control N2 - Ultrasound waves penetrate solid objects without damaging them. Their fields of application range from the imaging of internal organs in medicine, to interior testing of mechanical and chemical engineering components. However, ultrasonic systems can also be used to visualise the way the mechanical properties of reactive resins change during processing in the mould. PY - 2001 SN - 0945-0084 VL - 91 IS - 1 SP - 35 EP - 36 PB - Hanser CY - München AN - OPUS4-2135 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Döring, Joachim A1 - Stark, Wolfgang A1 - Bartusch, Jürgen A1 - Mc Hugh, Jarlath T1 - Contribution to ultrasound cure control for composite manufacturing N2 - The curing conditions play an important role in the quality assurance of composite products. Especially as composite materials are widely used in high tech areas so that they are required to fulfil high quality Standards. Some problems which occur during curing, for instance undercuring, can hardly be detected using Standard NDT investigations, mainly because they are manifested only at high temperatures, particularly close to glass-rubber-transition. On-line eure monitoring has the outstanding advantage that it can monitor the material parameters even at the highest temperatures possible. In recent years eure monitoring with ultrasonic methods has become more populär. In comparison to dielectric methods mechanical parameters are measured directly. The quantities to be measured are the velocity and the attenuation of the sound wave. On this basis the storage and loss modulus can be calculated. Depending on the form of excitation with longitudinal or transversal waves these moduli are referred to as long wave or shear modulus. Well developed Computer based technology and sensor materials are available in the non-destructive testing (NDT) market. The measuring equipment employed a commercial NDT System, which worked computer-aided. With a special Software the demands of automatic Operation under industrial conditions was accomplished. This measurement equipment was tested on composites. Its structure, performance and some practical results will be presented in the following paper. T2 - 15th World Conference on Non-Destructive Testing (WCNDT) CY - Roma, Italy DA - 15.10.2000 PY - 2000 UR - http://www.ndt.net/article/wcndt00/papers/idn482/idn482.htm SN - 1435-4934 VL - 5 IS - 11 PB - NDT.net CY - Kirchwald AN - OPUS4-2136 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Döring, Joachim A1 - Stark, Wolfgang T1 - Produktionskontrolle mit Ultraschall N2 - Ultraschallwellen durchdringen Festkörper, ohne sie zu schädigen. Der Einsatzbereich von Ultraschall reicht von der Darstellung der inneren Organe in der Medizin bis zur Prüfung des Inneren von Bauteilen im Maschinen- und Anlagenbau. Ultraschall-Systeme können jedoch auch genutzt werden, um sichtbar zu machen, wie sich mechanische Eigenschaften von Reaktionsharzen während ihrer Verarbeitung im Werkzeug verändern. PY - 2001 UR - http://www.kunststoffe.de/directlink.asp?KU101838 SN - 0023-5563 VL - 91 IS - 1 SP - 83 EP - 85 PB - Hanser CY - München AN - OPUS4-2137 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Döring, Joachim A1 - Bartusch, Jürgen A1 - Mc Hugh, Jarlath A1 - Stark, Wolfgang A1 - Kürten, C. T1 - Mit Ultraschall sieht man mehr - Kontrolle von Werkzeugfüllung und Vernetzungsreaktion beim Harzinjektionsverfahren RTM T2 - Poster-Ausstellung "Sensorik in der BAM" CY - Berlin, BAM, Deutschland DA - 2002-10-01 PY - 2002 SP - 1(?) AN - OPUS4-2114 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Untersuchungen zum Aushärteverhalten und zum Aushärtungszustand von Epoxidharz T2 - VII Internationale AVK-TV Konferenz CY - Baden-Baden, Germany DA - 2004-09-28 PY - 2004 AN - OPUS4-4759 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -