TY - JOUR A1 - Gallo, Emanuela A1 - Schartel, Bernhard A1 - Schmaucks, G. A1 - von der Ehe, Kerstin A1 - Böhning, Martin T1 - Effect of well dispersed amorphous silicon dioxide in flame retarded styrene butadiene rubber N2 - Spherically shaped amorphous silicon dioxide with broad size particle distribution was used in combination with aluminium trihydroxide (ATH) in styrene butadiene rubber composites. The pyrolysis, flammability, fire properties, flame spread and gas diffusion were investigated. The kind and amount of ATH, but in particular the fine silicon dioxide chosen as an additive, influenced the thermal decomposition and fire behaviour of styrene butadiene rubber composites. Gravimetric gas sorption measurements showed that the gas diffusion was systematically lower with silicon dioxide. The initial pyrolysis gas release was hindered, increasing the temperature at which decomposition begins as well as the ignition time in fire tests. During combustion, ATH and silicon dioxide accumulate on the surface of the specimen, forming a residual protective layer. A reduced peak heat release rate and fire spread were observed. The addition of a special kind of silicon dioxide is proposed to play a key role in optimising fire retardancy. KW - Flame retardancy KW - Styrene butadiene rubber KW - SBR KW - Silicon dioxide KW - Aluminium trihydroxide KW - ATH PY - 2013 U6 - https://doi.org/10.1179/1743289812Y.0000000012 SN - 1465-8011 SN - 1743-2898 VL - 42 IS - 1 SP - 34 EP - 42 PB - IOM Communications CY - London, UK AN - OPUS4-27626 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Wolff, Dietmar A1 - von der Ehe, Kerstin A1 - Jaunich, Matthias A1 - Böhning, Martin A1 - Goering, Harald ED - Yamamoto, T. T1 - (U)HMWPE as neutron radiation shielding materials: impact of gamma radiation on structure and properties N2 - Due to their extreme high hydrogen contents, high molecular weight (HMW-) and ultra-high molecular weight (UHMW-) polyethylene (PE) are a comprehensible choice as neutron radiation shielding material in casks for storage and transport of radioactive materials. But as a direct consequence of inserting radioactive material in such casks, gamma radiation occurs. Hence, the impact of gamma radiation on the molecular structure of polyethylene has to be taken into consideration. Consequently, PE has to withstand any type of gamma radiation induced degradation affecting safety relevant aspects in order to be applicable for long term neutron radiation shielding purposes during the whole storage period (in Germany, for instance, up to 40 years). The scope of our investigation comprises an estimation of the impact of gamma radiation and temperature on the molecular and supra molecular structure of the two types of PE used as neutron radiation shielding cask components. A further point which is worth exploring is to what extent these changes are detectable by conventional analysis methods. Therefore, thermoanalytical measurements were performed such as differential scanning calorimetry (DSC), thermo mechanical analysis (TMA), dynamic mechanical analysis (DMA), and thermo gravimetric analysis (TGA). Additionally optical and weighing methods were applied. With those methods it is possible to detect structural changes in polyethylene induced by exposure to gamma radiation. The observed amounts of changes of the irradiated material are not safety relevant for the application of polyethylene as neutron radiation shielding material; moreover, some properties actually improve via irradiation. KW - HMW-PE KW - UHMW-PE KW - Gamma irradiation KW - Neutron radiation shielding material PY - 2013 SN - 978-0-8031-7533-4 U6 - https://doi.org/10.1520/STP103980 N1 - Serientitel: STP – Series title: STP VL - 25 IS - STP 1547 SP - 211 EP - 227 AN - OPUS4-27931 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -