TY - JOUR A1 - Hölck, Ole A1 - Heuchel, M. A1 - Böhning, Martin A1 - Hofmann, D. T1 - Simulation of Experimentally Observed Dilation Phenomena During Integral Gas Sorption in Glassy Polymers N2 - A molecular modeling investigation of dilation effects induced by sorbed gas molecules in two glassy polymers is presented. As experimental reference, integral sorption of CO2 and CH4 was measured for polysulfone (PSU) and a polyimide (6FDA-TrMPD, PI4) at 308 K and a pressure of 10 bar. Simultaneously, the gas induced swelling effect was measured with a dilatometer based on a capacitive distance sensor recorded. The experimental evidence of the (on the observed time scale and concentration levels) elastic nature of the gas induced dilation is supported by the dilation and contraction behavior observed in molecular dynamics (MD) simulations of respective detailed atomistic packing models. These models were constructed in accordance with gas concentration levels obtained from the experimental sorption results. Quantitative deviations between simulated and measured dilations are discussed as a consequence of an anelastic response of the polymer matrix which is too fast to be resolved in the experiments whose kinetics is dominated by diffusional processes. In the simulation, the initial insertion of penetrant molecules into equilibrated packing models circumvents the slow diffusional process of the experiment and allows a reasonable representation of the dilation process as well as a closer investigation. Our simulation approach reveals a different behavior for PSU and PI4 on the corresponding time scale. Most likely, the different chain mobility of the two polymers is responsible for the respective response to the inserted amount of gas molecules which is discussed in terms of the different chain mobilities of the two polymers. KW - Diffusion KW - Dilation KW - Gas sorption KW - Molecular modeling KW - Poly(ether sulfones) KW - Polyimides KW - Swelling PY - 2008 DO - https://doi.org/10.1002/polb.21342 SN - 0887-6266 SN - 1099-0488 VL - 46 IS - 1 SP - 59 EP - 71 PB - Wiley CY - Hoboken, NJ AN - OPUS4-16206 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hölck, Ole A1 - Böhning, Martin A1 - Heuchel, M. A1 - Siegert, M.R. A1 - Hofmann, D. T1 - Gas sorption isotherms in swelling glassy polymers - detailed atomistic simulations N2 - Detailed atomistic simulations were carried out for swelling polymer/gas systems related to experimental sorption and dilation data for CO2 and CH4 in three glassy polymers (polysulfone PSU, the polyimide 6FDA-TrMPD, and a polymer of intrinsic microporosity PIM-1) at 308 K (35 °C) and pressures up to 50 bar. Corresponding experiments were performed with a gravimetric sorption balance and a dilatometer based on a capacitance distance sensor. For each polymer/gas system molecular packing models were prepared and equilibrated for two reference states: the pure polymer is taken as reference for the respective 'unswollen' state and similarly the state of the highest penetrant pressure reached in the corresponding experiment is taken to represent the 'swollen' state. Models for the latter were constructed in agreement with experimental data (pressure, temperature, gas concentration and volume dilation). Concentration–pressure isotherms of each polymer/gas system were obtained using Grand Canonical Monte Carlo (GCMC) simulations for both reference states (depleted of gas molecules), which are in good agreement with the experimental data in the respective pressure range. As expected these isotherms – due to the simulation technique used, merely based on hole-filling in a static host matrix – do not represent the sorption behavior over a broader range of gas pressures which may involve significant structural rearrangements as well as swelling and relaxational phenomena. Nevertheless, a linear combination of the two GCMC-isotherms allows the interpolation in order to describe the nonlinear gas sorption in the glassy polymers under investigation covering the penetrant pressure range between the reference states in good agreement with the experimental results. KW - Gas sorption KW - Dilation KW - Molecular modeling KW - Polysulfone KW - Polyimide KW - Polymer of intrinsic microporosity (PIM-1) PY - 2013 DO - https://doi.org/10.1016/j.memsci.2012.10.023 SN - 0376-7388 SN - 1873-3123 VL - 428 SP - 523 EP - 532 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-27599 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hieronymus, Hartmut A1 - Hofmann, Martin A1 - Bender, Josef A1 - Henschen, Philipp A1 - Wendler, Reinhold A1 - Plewinsky, Bodo A1 - Steinbach, J. T1 - Characterization of surface explosions PY - 2001 SN - 0208-4198 VL - 21 IS - 2 SP - 117 EP - 125 PB - Wydawn. Naukowe PWN CY - Warszawa AN - OPUS4-1213 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heuchel, M. A1 - Böhning, Martin A1 - Hölck, Ole A1 - Siegert, M.R. A1 - Hofmann, D. T1 - Atomistic Packing Models for Experimentally Investigated Swelling States Induced by CO2 in Glassy Polysulfone and Poly(ether sulfone) N2 - Atomistic packing models have been created, which help to better understand the experimentally observed swelling behavior of glassy polysulfone and poly (ether sulfone), under CO2 gas pressures up to 50 bar at 308 K. The experimental characterization includes the measurement of the time-dependent volume dilation of the polymer samples after a pressure step and the determination of the corresponding gas concentrations by gravimetric gas-sorption measurements. The models obtained by force-field-based molecular mechanics and molecular dynamics methods allow a detailed atomistic analysis of representative swelling states of polymer/gas systems, with respect to the dilation of the matrix. Also, changes of free volume distribution and backbone mobility are accessible. The behavior of gas molecules in unswollen and swollen polymer matrices is characterized in terms of sorption, diffusion, and plasticization. KW - Molecular modeling KW - Volume dilation KW - Gas sorption KW - Poly(ether sulfones) KW - Free volume KW - Swelling KW - Molecular dynamics KW - Diffusion KW - Plasticization PY - 2006 DO - https://doi.org/10.1002/polb.20844 SN - 0887-6266 SN - 1099-0488 VL - 44 IS - 13 SP - 1874 EP - 1897 PB - Wiley CY - Hoboken, NJ AN - OPUS4-12398 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heuchel, M. A1 - Böhning, Martin A1 - Hölck, Ole A1 - Siegert, M.R. A1 - Hofmann, D. T1 - Atomistic packing models for experimentally investigated swelling states induced by CO2 in glassy polymers KW - Glassy polymers KW - Sorption KW - Swelling KW - Molecular Modelling PY - 2006 DO - https://doi.org/10.1016/j.desal.2006.03.100 SN - 0011-9164 VL - 199 IS - 1-3 SP - 443 EP - 444 PB - Elsevier CY - Amsterdam AN - OPUS4-13708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böhning, Martin A1 - Hölck, Ole A1 - Heuchel, M. A1 - Hofmann, D. T1 - Characterization of gas sorption in glassy polymers combining experimental and molecular modeling techniques KW - Glassy Polymers KW - Gas Sorption KW - Molecular Modelling KW - Diffusion PY - 2008 SN - 0743-0515 VL - 98 SP - 875 EP - 876 PB - Division of Polymeric Materials Science and Engineering, American Chemical Society CY - Washington, DC AN - OPUS4-17485 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Werrel, Martin A1 - Deubel, Jan A1 - Krüger, Simone A1 - Hofmann-Böllinghaus, Anja A1 - Krause, U. T1 - The calculation of the heat release rate by oxygen consumption in a controlled-atmosphere cone calorimeter N2 - The standard cone calorimeter according to ASTM E 1354 and ISO 5660 enables reaction-to-fire tests to be performed in ambient atmospheric conditions. A controlled-atmosphere chamber modifies the standard apparatus in a way that allows tests to be performed in nonambient conditions as well. The enclosed chamber is placed underneath the standard exhaust hood and does not have a closed connection to the hood. With this open arrangement, the exhaust gases are diluted by excess air drawn in from the laboratory surroundings. Heat-induced changes in the consequential dilution ratio affect the calculation of fire quantities and, when neglected, lead to deviations of up to 30% in heat release rate. The paper introduces a test protocol and equations to calculate the heat release rate taking dilution effects into account. A mathematical correction is shown that compensates for the dilution effects while avoiding extensive mechanical changes in the equipment. KW - Controlled-atmosphere cone calorimeter KW - Heat release rate KW - Oxygen consumption KW - Cone calorimeter KW - Vitiation and ventilation control KW - Excess air PY - 2014 DO - https://doi.org/10.1002/fam.2175 SN - 0308-0501 SN - 1099-1018 VL - 38 IS - 2 SP - 204 EP - 226 PB - Heyden CY - London AN - OPUS4-30317 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -