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 U6 - 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 - Stark, Wolfgang A1 - Döring, Joachim A1 - Walentowski, Heinz-Ulrich T1 - Crosslinking Instead of Glassy Transition N2 - In processing fibre-reinforced composites, the curing reaction can be significantly retarded if the temperature and reaction time are not optimally set. In such situations, complete curing is sometimes impossible under practically relevant conditions. It is difficult for processors to recognize or detect incomplete curing. The equilibrium glass transition temperature plays an important role in complete curing in the production process. PY - 2000 SN - 0945-0084 VL - 90 IS - 4 SP - 33 EP - 35 PB - Hanser CY - München AN - OPUS4-822 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Döring, Joachim A1 - Stark, Wolfgang A1 - Mc Hugh, Jarlath A1 - Bartusch, Jürgen T1 - Ultrasound on-line cure monitoring for industrial applications N2 - In recent years eure monitoring with ultrasonic methods became more important. An on-line measurement System for industrial applications is presented in this paper. It operates in through-transmission and the measured parameters are the sound velocity and the attenuation of the sound wave. An objective of this paper is to establish the ränge of possible applications for an ultrasonic eure monitoring System. KW - Ultrasonic monitoring KW - Cure process KW - Composite material KW - Process controlling PY - 2000 SN - 0963-6935 PB - Woodhead Publ. CY - Cambridge AN - OPUS4-1061 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bovtun, Viktor Petrovic A1 - Stark, Wolfgang A1 - Kelm, Jürgen A1 - Porokhonskyy, V. A1 - Yakimenko, Y. T1 - Microwave Dielectric Properties of Rubber Compounds Undergoing Vulcanisation - Part 1. Natural rubber with and without carbon black filler KW - Dielectric parameters KW - Microwave methods KW - Vulcanisation KW - Elastomers KW - Monitoring PY - 2000 SN - 0948-3276 SN - 0022-9520 PB - Hüthig CY - Heidelberg AN - OPUS4-1062 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Gorokhovatsky, Y.A. A1 - Krüger, Simone A1 - Brademann-Jock, Kerstin A1 - Stark, Wolfgang A1 - Temnov, Dmitri A1 - Kuvshinova, Oksana A1 - Goldade, V.A. ED - Fleming, R. J. T1 - Thermally stimulated luminescence in LDPE fibers T2 - 11th International Symposium on Electrets (ISE 11) CY - Melbourne, Australia DA - 2002-10-01 PY - 2002 SN - 0-7803-7560-2 SP - 138 EP - 140 PB - IEEE Service Center CY - Piscataway, NJ AN - OPUS4-1654 LA - eng 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 - JOUR A1 - Bovtun, V. A1 - Stark, Wolfgang A1 - Kelm, Jürgen A1 - Porokhonskyy, V. A1 - Yakimenko, Y. T1 - Microwave Dielectric Properties of Rubber Compounds Undergoing Vulcanisation - Part 2. Influence of Carbon Black N2 - The application of microwave measurements to the characterisation of rubber compounds vulcanisation is considered. The behaviour of mechanical and microwave (20 GHz) dielectric parameters during vulcanisation was investigated for rubber compounds with different concentrations of active and non-active carbon black. An increase of concentration or activity of carbon black results in the increase of both dielectric permittivity ε?(T) and loss ε?(T) and in the increase of torsion modulus as well. The start of the vulcanisation reaction is indicated by an increase of dielectric permittivity and torsion modulus in all investigated unvulcanised compounds with carbon black. While for compounds with non-active carbon black the vulcanisation can be better indicated by the ε?(T) anomaly, for compounds with active carbon black it is more clearly seen by the change of ε?(T) behaviour. PY - 2002 UR - http://www.plastverarbeiter.de/ai/resources/d5af83c1e48.pdf SN - 0948-3276 SN - 0022-9520 VL - 55 IS - 1-2 SP - 16 EP - 22 PB - Hüthig CY - Heidelberg AN - OPUS4-1564 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 - GEN A1 - Stark, Wolfgang A1 - Döring, Joachim A1 - Kelm, Jürgen A1 - Fritsch, Sebastian ED - Green, R. E. ED - Djordjevic, B. B. ED - Hentschel, M. P. T1 - Rubber processing monitored by ultrasound T2 - 11th International Symposium on Nondestructive Characterization of Materials CY - Berlin, Germany DA - 2002-06-24 PY - 2003 SN - 3-540-40154-7 SP - 659 EP - 664 PB - Springer CY - Berlin AN - OPUS4-2769 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Mc Hugh, Jarlath A1 - Stark, Wolfgang A1 - Döring, Joachim ED - Green, R. E. ED - Djordjevic, B. B. ED - Hentschel, M. P. T1 - Evaluation of the cure behaviour of epoxy resin using rheometric and ultrasonic techniques T2 - 11th International Symposium on Nondestructive Characterization of Materials CY - Berlin, Germany DA - 2002-06-24 PY - 2003 SN - 3-540-40154-7 SP - 651 EP - 658 PB - Springer CY - Berlin AN - OPUS4-2772 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 - 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 A1 - Goering, Harald A1 - Bayerl, H. A1 - Hoster, B. T1 - Post-annealing of thermosets T2 - 4th International Thermoset Conference CY - Iserlohn, Germany DA - 2006-11-16 PY - 2006 AN - OPUS4-13801 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang T1 - Dielektric Process Monitoring of Thermosetting Resins T2 - DEA-Seminar, Achema-Messe CY - Frankfurt am Main, Germany DA - 2003-05-22 PY - 2003 AN - OPUS4-4071 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stark, Wolfgang A1 - Döring, Joachim A1 - Goering, Harald A1 - Mc Hugh, Jarlath A1 - Opfermann, J. A1 - Knappe, S. T1 - The RTM-Process and the Problems with Gelation, Vitrification and Degree of Curing T2 - 6th Internationale AVK-Tv Conference CY - Baden-Baden, Germany DA - 2003-09-07 PY - 2003 AN - OPUS4-4072 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cappella, Brunero A1 - Stark, Wolfgang T1 - Adhesion of amorphous polymers as a function of temperature probed with AFM force-distance curves N2 - Force–displacement curves have been obtained with a commercial atomic force microscope at different temperatures and probe rates on a thick film of poly(n-butyl methacrylate) and on two films of polystyrene with different molecular weight. In a previous publication [B. Cappella, S.K. Kaliappan, H. Sturm, Macromolecules 38 (2005)1874] the analysis of force–displacement curves has been focused on the stiffness and on the Young's modulus of the samples. In the present publication we consider the temperature dependence of the work of adhesion. We have obtained master curves of the work of adhesion at fixed maximum loads and, by comparing the results of the two analysis, we show that the work of adhesion follows the Williams–Landel–Ferry equation with the same coefficients previously found for the Young's modulus. Furthermore, we show that the temperature dependence of the work of adhesion of the polymers is a consequence of the temperature dependence of the tip–sample contact area and in the end of the temperature dependence of the stiffness and of the elastic–plastic properties of the samples. KW - Atomic force microscope KW - Force-distance curves KW - Indentation KW - Elastic-plastic properties KW - Adhesion KW - Time-temperature superposition principle KW - Glass transition temperature PY - 2005 U6 - https://doi.org/10.1016/j.jcis.2005.09.043 SN - 0021-9797 SN - 1095-7103 SP - 1 EP - 8(?) PB - Elsevier CY - Orlando, Fla. AN - OPUS4-11187 LA - eng 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 - Stark, Wolfgang A1 - Fritsch, Sebastian A1 - Kelm, Jürgen T1 - Vulcanization Monitoring in the Mould by Means of Ultrasound T2 - German Rubber Conference 2006 CY - Nuremberg, Germany DA - 2006-07-03 KW - Vulkanisation KW - Ultraschall KW - Prozesskontrolle KW - Rheologie PY - 2006 SP - 189 EP - 193 PB - Deutsche Kautschuk-Gesellschaft CY - Frankfurt am Main AN - OPUS4-13082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wolff, Dietmar A1 - Jaunich, Matthias A1 - Stark, Wolfgang T1 - Investigating the performance of rubber seals at low temperatures N2 - Rubbers are widely used as main sealing materials for Containers for low and intermediate level radioactive waste and as additional component to metal seals in spent fuel and high active waste containers. The save enclosure of the radioactive container inventory has to be guaranteed according to legislation and appropriate guidelines for long term storage periods as well as down to temperatures of -40 °C for transportation. Therefore the understanding of failure mechanisms that lead to leakage at low temperatures is necessary to ensure a proper material choice which is certainly also influenced by additional factors as e.g. the aging behavior. T2 - 14th International high-level radioactive waste management conference CY - Albuquerque, New Mexico, USA DA - 28.04.2013 KW - Rubber seals KW - Elastomers KW - Compression set KW - Low temperature KW - Leakage rate PY - 2013 SN - 978-1-62748-644-6 SP - 1 EP - 7(Paper # 6888) PB - Omnipress AN - OPUS4-28530 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Stark, Wolfgang A1 - Wolff, Dietmar T1 - Low temperature - For a seal this depends on the applied material T2 - DKT 2012 - German Rubber Conference CY - Nuremberg, Germany DA - 2012-07-02 PY - 2012 IS - 10-2330_5-L-1530 SP - 1 EP - 4 PB - Deutsche Kautschuk-Gesellschaft CY - Frankfurt am Main AN - OPUS4-26190 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -