TY - JOUR A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed A. A1 - Böhning, Martin A1 - Frick, B. A1 - Apple, M. A1 - Mole, R. A. A1 - De Souza, N. R. A1 - Zorn, R. A1 - Schönhals, Andreas T1 - Confined Segmental Diffusion in Nanophase Separated Janus Polynorbornenes as Investigated by Quasielastic Neutron Scattering N2 - A combination of neutron time-of-flight and neutron backscattering spectroscopy was used to investigate the molecular dynamics of Janus polynorbornenes (Janus poly(tricyclononenes)) on a microscopic level. These Janus polynorbornenes, denoted as PTCNSiOR, have a semirigid backbone with −Si(OR)3 side groups attached to it. R represents the length of the alkyl side chain. Here side chain lengths of R = 3 (propyl) and R = 8 (octyl) were considered. It is worth mentioning that these polymers have some potential as active layers in gas separation membranes, especially for the separation of higher hydrocarbons. The combination of time-of-flight and backscattering will ensure a reasonably broad time window for analysis where the incoherent intermediate scattering function SInc(q,t) is considered. Previously, it was shown by X-ray investigations that the system undergoes a nanophase separation into alkyl side chain-rich domains surrounded by a backbone-rich matrix. For PTCNSiOPr (R = 3), the alkyl side-chain-rich domains are truly isolated in the backbone-rich matrix, whereas for PTCNSiOOc (R = 8) these domains percolate through the matrix. Further, it was also previously shown that the alkyl side-chain-rich domains undergo a glass transition. The advantage of neutron scattering experiments discussed here is that besides temporal also spatial information is obtained which will allow conclusions to be drawn about the type of molecular fluctuations. At the lowest measured temperature, the decay in Sinc(q,t) is due to the methyl group rotation. The methyl group dynamics is analyzed in terms of a modified jump-diffusion in a 3-fold potential and yields to a reasonable fraction of hydrogens which contribute to the methyl group rotation. At higher temperatures, the decay in SInc(q,t) is due to both the methyl group rotation and the segmental dynamics in the alkyl side-chain-rich domains. The segmental diffusion is modeled by a sublinear diffusion. For the analysis of the scattering function SInc(q,t) of PTCNSiOPr an elastic scattering due to the immobilized backbone-rich matrix must be taken into account. The analysis reveals that the segmental dynamics is confined by the finite size of alkyl chain-rich domains and that it is intrinsically heterogeneous in nature. Both effects are more pronounced for PTCNSiOPr in comparison to those of PTCNSiOOc. KW - Polynorbornene KW - Quasielastic Neutron Scattering PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608712 DO - https://doi.org/10.1021/acs.macromol.4c01045 SP - 1 EP - 14 PB - ACS Publications AN - OPUS4-60871 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilling, Markus A1 - Marschall, Niklas A1 - Niebergall, Ute A1 - Wachtendorf, Volker A1 - Böhning, Martin T1 - Characteristics of environmental stress cracking of PE-HD induced by biodiesel and diesel fuels N2 - In the context of the increasing effect of carbon dioxide emissions on the global climate biodiesel produced from renewable sources has emerged as a promising contender replacing fossil fuels, especially in long-range transport vehicles, using existing engines and infrastructure. High-density polyethylene is one of the prevailing materials for pipe and container applications for storage and transport of such fuels, both, from fossil and renewable resources. The contact with the respective fuels raises questions concerning material compatibility as biodiesel exhibits significant differences compared to conventional diesel fuel affecting its sorption and plasticization behavior in polyethylene. In this study, its behavior with respect to environmental stress cracking, considered one of the most frequent damage mechanisms leading to failure of polymer parts and packaging, was evaluated using the well-established Full Notch Creep Test. This approach allows for a detailed fracture surface analysis using imaging techniques, such as optical and laser scanning microscopy, as well as infrared spectroscopy. Comparing the environmental stress cracking behavior in standard surfactant solutions with that in biodiesel and diesel, respective crack propagation rates, showing different levels of acceleration, were determined and details of the underlying mechanisms could be revealed. Furthermore, the specific infrared absorption of the biodiesel’s ester functionality allows its semi-quantitative determination on the fracture surface of the tested specimens after failure. Thus, a preferred uptake of sorptive fluids in the fracture zone due to local morphological changes of the polyethylene could be directly evidenced by infrared spectroscopy. KW - Environmental stress cracking (ESC) KW - Full notch creep test (FNCT) KW - Confocal laser scanning microscopy (LSM) KW - Biodiesel KW - Diesel PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608591 DO - https://doi.org/10.1016/j.polymertesting.2024.108547 SN - 0142-9418 VL - 138 SP - 1 EP - 16 PB - Elsevier Ltd. AN - OPUS4-60859 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed A. A1 - Böhning, Martin A1 - De Souza, N. R. A1 - Juranyi, F. A1 - Zorn, R. A1 - Schönhals, Andreas T1 - Inelastic and Quasielastic Neutron Scattering on Polynorbornenes with Bulky Carbocyclic Side groups N2 - This study investigates the molecular mobility and vibrational properties of polynorbornenes with bulky carbocyclic side groups using inelastic and quasielastic neutron scattering techniques. The polymers, synthesized via metathesis and addition polymerization, exhibit varying degrees of microporosity, which ignificantly influences their gas separation performance. By inelastic neutron scattering experiments, it could be shown that all considered polymers have excess contributions to the low frequency vibrational density of states known as the Boson peak. The maximum frequency of the Boson peak correlates to the microporosity of the polymers. This correlation supports the sound wave interpretation of the Boson peak, suggesting that the microporous structure enhances the compressibility of the material at a microscopic length scale. The molecular mobility, particularly the methyl group rotation, was characterized using elastic scans and quasielastic neutron scattering. The study revealed a temperature dependent relaxation process, with the onset of molecular fluctuations observed around 200 K for the polymer containing methyl groups. For the polymer having no methyl groups only elastic scattering is observed. The methyl group rotation was analyzed in terms of a jump diffusion in a threefold potential with three equivalent energy minima. This leads to an almost correct description of the q dependence of the elastic incoherent scattering function when the number of hydrogen nuclei undergoing the methyl group rotation is considered. It was further evidenced that the fraction of methyl undergoing the methyl group rotation increases with increasing temperature. KW - Polymers of Intrinsic Microporosity KW - Neutron scattering PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630297 DO - https://doi.org/10.1016/j.polymer.2025.128358 SN - 1873-2291 VL - 328 SP - 241 PB - Elsevier Ltd. AN - OPUS4-63029 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zorn, R. A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed Aejaz A1 - Malpass-Evans, R. A1 - McKeown, N. A1 - Jalarvo, N. A1 - Tyagi, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Microscopic molecular mobility of high-performance polymers of intrinsic microporosity revealed by neutron scattering – bend fluctuations and signature of methyl group rotation N2 - Polymers of intrinsic microporosity exhibit a combination of high gas permeability and reasonable permselectivity, which makes them attractive candidates for gas separation membrane materials. The diffusional selective gas transport properties are connected to the molecular mobility of these polymers in the condensed state. Incoherent quasielastic neutron scattering was carried out on two polymers of intrinsic microporosity, PIM-EA-TB(CH3) and its demethylated counterpart PIM-EA-TB(H2), which have high Brunauer–Emmett–Teller surface area values of 1030 m2 g-1 and 836 m2 g-1, respectively. As these two polymers only differ in the presence of two methyl groups at the ethanoanthracene unit, the effect of methyl group rotation can be investigated solely. To cover a broad dynamic range, neutron time-of-flight was combined with neutron backscattering. The demethylated PIM-EA-TB(H2) exhibits a relaxation process with a weak intensity at short times. As the backbone is rigid and stiff this process was assigned to bendand-flex fluctuations. This process was also observed for the PIM-EA-TB(CH3). A further relaxation process is found for PIM-EA-TB(CH3), which is the methyl group rotation. It was analyzed by a jump-diffusion in a three-fold potential considering also the fact that only a fraction of the present hydrogens in PIM-EATB(CH3) participate in the methyl group rotation. This analysis can quantitatively describe the q dependence of the elastic incoherent structure factor. Furthermore, a relaxation time for the methyl group rotation can be extracted. A high activation energy of 35 kJ mol-1 was deduced. This high activation energy evidences a strong hindrance of the methyl group rotation in the bridged PIM-EA-TB(CH3) structure. KW - Polymers of Intrinsic Microporosity KW - Neutron Scattering PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604114 DO - https://doi.org/10.1039/d4sm00520a SP - 1 EP - 11 PB - RSC AN - OPUS4-60411 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thuy, Maximilian A1 - Pedragosa-Rincon, M. A1 - Niebergall, Ute A1 - Oehler, H. A1 - Alig, I. A1 - Böhning, Martin T1 - Environmental Stress Cracking of High-Density Polyethylene Applying Linear Elastic Fracture Mechanics N2 - The crack propagation rate of environmental stress cracking was studied on high-density polyethylene compact tension specimens under static loading. Selected environmental liquids are distilled water, 2 wt% aqueous Arkopal N100 solution, and two model liquid mixtures, one based on solvents and one on detergents, representing stress cracking test liquids for commercial crop protection products. The different surface tensions and solubilities, which affect the energetic facilitation of void nucleation and craze development, are studied. Crack growth in surface-active media is strongly accelerated as the solvents induce plasticization, followed by strong blunting significantly retarding both crack initiation and crack propagation. The crack propagation rate for static load as a function of the stress intensity factor within all environments is found to follow the Paris–Erdogan law. Scanning electron micrographs of the fracture surface highlight more pronounced structures with both extensive degrees of plasticization and reduced crack propagation rate, addressing the distinct creep behavior of fibrils. Additionally, the limitations of linear elastic fracture mechanisms for visco-elastic polymers exposed to environmental liquids are discussed. KW - Crack propagation KW - Environmental stress cracking KW - Fracture toughness KW - Crop protection products KW - High-density polyethylene KW - Craze–crack mechanism KW - Linear elastic fracture mechanics KW - Stress intensity factor PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-550476 DO - https://doi.org/10.3390/polym14122415 SN - 2073-4360 VL - 14 IS - 12 SP - 1 EP - 21 PB - MDPI CY - Basel AN - OPUS4-55047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zorn, R. A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed Aejaz A1 - Malpass-Evans, R. A1 - McKeown, N. A1 - Tyagi, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Low frequency vibrations and diffusion in disordered polymers bearing an intrinsic microporosity as revealed by neutron scattering N2 - The microscopic diffusion and the low frequency density of states (VDOS) of PIM-EATB(CH3) are investigated by inelastic and quasi-elastic neutron scattering where also the demethylated counterpart of PIM-EA-TB(H2) is considered. These intrinsic microporous polymers are characterized by large BET surface area values of several hundred m2/g and pore sizes between 0.5 and 2 nm. Detailed comparison is made to the archetype of polymers of intrinsic microporosity, PIM-1, and polynorbornenes also bearing a microporosity. Due to the wavelength of neutrons, the diffusion and vibrations can be addressed on microscopic length and time scales. From the inelastic neutron scattering experiments the low frequency density of states (VDOS) is estimated which shows excess contributions to the Debye-type VDOS known as Boson peak. It was found that the maximum frequency of the Boson peak decreases with increasing microporosity characterized by the BET surface area. However, besides the BET surface area, additional factors such as the backbone stiffness govern the maximum frequency of the Boson peak. Further the mean squared displacement related to microscopic motions was estimated from elastic fixed window scans. At temperatures above 175 K, the mean squared displacement PIM-EA-TB(CH3) is higher than that for the demethylated counterpart PIM-EA-TB(H2). The additional contribution found for PIM-EATB(CH3) is ascribed to the rotation of the methyl group in this polymer because the only difference between the two structures is that PIM-EA-TB(CH3) has methyl groups where PIM-EA-TB(H2) has none. A detailed comparison of the molecular dynamics is also made to that of PIM-1 and the microporous polynorbornene PTCNSi1. The manuscript focuses on the importance of vibrations and the localized molecular mobility characterized by the microscopic diffusion on the gas Transport in polymeric separation membranes. In the frame of the random gate model localized fluctuations can open or close bottlenecks between pores to enable the diffusion of gas molecules. KW - Polymer of intrisic microporosity KW - Neutron scattering KW - Boson peak KW - Methyl group rotation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538490 DO - https://doi.org/10.3390/cryst11121482 VL - 11 IS - 12 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-53849 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolmangadi, Mohamed Aejaz A1 - Szymoniak, Paulina A1 - Zorn, R. A1 - Böhning, Martin A1 - Wolff, M. A1 - Zamponi, M. A1 - Schönhals, Andreas T1 - Molecular mobility in high-performance polynorbornenes:A combined broadband dielectric, advanced calorimetry,and neutron scattering investigation N2 - The molecular dynamics of two addition type polynorbornenes, exo-PNBSiand PTCNSi1, bearing microporosity has been investigated by broadbanddielectric spectroscopy, fast scanning calorimetry, and neutron scattering. Bothpolymers have the same side groups but different backbones. Due to theirfavorable transport properties, these polymers have potential applications inseparation membranes for gases. It is established in literature that molecularfluctuations are important for the diffusion of small molecules through poly-mers. For exo-PNBSi, two dielectric processes are observed, which are assignedto Maxwell/Wagner/Sillars (MWS) process due to blocking of charge carriersat internal voids or pore walls. For PTCNSi1, one MWS-polarization process isfound. This points to a bimodal pore-size distribution for exo-PNBSi. A glasstransition for exo-PNBSi and for PTCNSi1 could be evidenced for the first timeusing fast scanning calorimetry. For Tgand the corresponding apparent activa-tion energy, higher values were found for PTCNSi1 compared to exo-PNBSi.For both polymers, the neutron scattering data reveal one relaxation process.This process is mainly assigned to methyl group rotation probably overlayedby carbon–carbon torsional fluctuations. KW - Advanced calorimetry KW - Dielectric spectroscopy KW - Neutron scattering KW - Polynorbornenes PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-547086 DO - https://doi.org/10.1002/pen.25995 SN - 0032-3888 VL - 62 IS - 7 SP - 2143 EP - 2155 PB - Wiley AN - OPUS4-54708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Erdmann, Maren A1 - Niebergall, Ute A1 - Wachtendorf, Volker A1 - Böhning, Martin T1 - Evaluation of UV-induced embrittlement of PE-HD by Charpy impact test N2 - The impact fracture behavior of two common high-density polyethylene grades for container applications were intensively studied by the instrumented Charpy impact test after well-defined exposure to UV-irradiation. Individual stages of the impact event, such as crack initiation and crack propagation energy as well as maximum impact load, were investigated from the recorded load–deflection curves. UV-induced material property changes were further investigated by infrared spectroscopy, differential scanning calorimetry, and dynamic-mechanical analysis as well as density measurements. Based on the results of the Charpy impact test, three indicators were identified to describe the extend of photooxidation on high-density polyethylene: (a) a reduced Charpy impact strength—at least to half of its initial value for a distinctly brittle impact fracture, (b) a marked decrease in the crack propagation contribution to the impact strength, and (c) an increase of the brittle features of the fracture surface. KW - Degradation KW - Mechanical properties KW - Packaging KW - Polyolefins KW - Polyethylene PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509130 DO - https://doi.org/10.1002/APP.49069 SN - 0021-8995 VL - 137 IS - 36 SP - 49069 PB - Wiley AN - OPUS4-50913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilling, Markus A1 - Niebergall, Ute A1 - Marschall, Niklas A1 - Alig, I. A1 - Böhning, Martin T1 - A phenomenological criterion for an optical assessment of PE-HD fracture surfaces obtained from FNCT N2 - The full-notch creep test (FNCT) is a common test method to evaluate the environmental stress cracking (ESC) behavior of high-density polyethylene (PE-HD), e.g. for container materials. The test procedure as specified in ISO 16770 provides a comparative measure of the resistance against ESC using the time to failure of PE-HD specimens under constant mechanical load in a well-defined liquid test environment. Since the craze-crack damage mechanism underlying the ESC phenomenon is associated with brittle failure, the occurrence of a predominantly brittle fracture surface is a prerequisite to consider an FNCT measurement as representative for ESC, i.e. a time to failure dominated by craze-crack propagation. The craze-crack propagation continuously reduces the effective residual cross-sectional area of the specimen during the test, which results in a corresponding increase of the effective mechanical stress. Thus, a transition to ductile shear deformation is inevitable at later stages of the test, leading usually to a pronounced central ligament. Therefore, an optical evaluation of FNCT fracture surfaces concerning their brittleness is essential. An enhanced imaging analysis of FNCT fracture surfaces enables a detailed assessment of craze-crack Propagation during ESC. In this study, laser scanning microscopy (LSM) was employed to evaluate whether FNCT fracture surfaces are representative with respect to craze-crack propagation and ESC. Based on LSM height data, a phenomenological criterion is proposed to assess the validity of distinct FNCT measurements. This criterion is supposed to facilitate a quick evaluation of FNCT results in practical routine testing. Its applicability is verified on a sample basis for seven different commercial PE-HD container materials. KW - Environmental stress cracking (ESC) KW - Full notch creep test (FNCT) KW - Laser scanning microscopy (LSM) KW - Fracture surfaces KW - Optical criterion of brittleness PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521012 DO - https://doi.org/10.1016/j.polymertesting.2020.107002 VL - 94 SP - 107002 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-52101 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Schönhals, Andreas A1 - Böhning, Martin A1 - Szymoniak, Paulina ED - Schönhals, Andreas ED - Szymoniak, Paulina T1 - (Nano)Composite Materials—An Introduction N2 - The chapter gives a brief introduction to (nano)compositecomposite materials having the focus on polymer-based nanocomposites. The different dimensionalities of nanoparticles are introduced, along with their distribution in the matrix. Different application fields of polymer-based nanocomposites, like flame retardancy, filled rubbers, nanofilled thermosets and thermoplastics, separation membranes and nanodielectrics, are considered in greater detail. KW - Polymer-based nanocomposites KW - Nanoparticle KW - Distribution of nanoparticles KW - Filled rubbers KW - Filled thermosets and plastics KW - Separation membranes KW - Nanodielectrics PY - 2022 DO - https://doi.org/10.1007/978-3-030-89723-9_1 SP - 1 EP - 31 PB - Springer CY - Cham, Switzerland AN - OPUS4-54565 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emamverdi, Farnaz A1 - Yin, Huajie A1 - Smales, Glen Jacob A1 - Harrison, W. J. A1 - Budd, P. M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Polymers of intrinsic microporosity - Molecular mobility and physical aging revisited by dielectric spectroscopy and X‑ray scattering N2 - Polymers of intrinsic microporosity (PIMs) are promising candidates for the active layer in gas separation membranes due to their high permeability and reasonable permselectivity. These appealing properties originate from a microporous structure as a result of inefficient segment packing in the condensed state due to a combination of a ladder-like rigid backbone and sites of contortion. However, this class of polymers suffers from a significant decrease in the permeability with time due to physical aging, whereby typically, the permselectivity increases. The initial microporous structures approach a denser state via local rearrangements, leading to the reduction of the permeability. Hence, a detailed characterization of the molecular mobility in such materials can provide valuable information on physical aging. In this work, the dielectric behavior of PIM-1 films and their behavior upon heating (aging) were revisited by isothermal frequency scans during different heating/cooling cycles over a broad temperature range between 133 and 523 K (−140 to 250 °C). In addition, the obtained results were compared with data of samples that were annealed at ambient temperatures over different time scales. Multiple dielectric processes were observed: several relaxation processes due to local fluctuations and a Maxwell−Wagner−Sillars polarization effect related to the microporosity. The temperature dependence of the rates of all processes follows the Arrhenius law where the estimated activation energy depends on the nature of the process. The influence of the thermal history (aging) on the processes is discussed in detail. KW - Polymers of intrinsic microporosity PY - 2022 DO - https://doi.org/10.1021/acs.macromol.2c00934 VL - 55 SP - 7340 EP - 7350 PB - American Chemical Society CY - Washington, DC AN - OPUS4-55485 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed A. A1 - Juranyi, Fanni A1 - Böhning, Martin A1 - Zorn, Reiner A1 - Schönhals, Andreas T1 - Low-Frequency Vibrational Density of State of Janus-Polynorbornenes: The Dependence of the Boson Peak on the Nanophase-Separated Structure N2 - Inelastic incoherent neutron time-of-flight scattering was employed to investigate the low-frequency vibrational density of states (VDOSs) for a series of glassy Janus-poly(tricyclononenes), which consist of a rigid main chain and flexible alkyl side chains. Here, the length of the flexible side chains was systematically varied from propyl to octyl. Such materials have potential applications as active separation layers in gas separation membranes as a green future technology, especially for the separation of higher hydrocarbons. From the morphological point of view, the Janus polynorbornenes undergo a nanophase separation into alkyl side chain-rich nanodomains surrounded by a rigid polynorbornene matrix. Here, the influence of the nanophase-separated structure on the low-frequency VDOS is investigated from a fundamental point of view. The low-frequency VDOSs of these Janus polynorbornene show excess contributions to the Debye type VDOS known as the Boson peak (BP) for all side chain lengths. Due to the high incoherent scattering cross-section of hydrogen, most of the scattering comes from the alkyl side chain-rich domains. Compared to conventional glass-forming materials, in the considered Janus polynorbornenes, the BP has a much lower intensity and its frequency position is shifted to higher values. These experimental results are discussed in terms of the nanophase-separated structure where the alkyl chain-rich domains were constrained by the surrounding matrix dominated by the rigid backbone. With increasing alkyl chain length, the size of the alkyl chain-rich domains increases. The frequency position of the BP shifts linearly to lower frequencies with the size of these nanodomains estimated from X-ray measurements. The obtained results support the sound wave interpretation to the BP KW - Inelastic neutron scattering PY - 2023 DO - https://doi.org/10.1021/acs.macromol.3c00913 SN - 0024-9297 SP - 1 EP - 10 PB - ACS AN - OPUS4-57972 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Szymoniak, Paulina A1 - Böhning, Martin A1 - Zorn, Reiner A1 - Schönhals, Andreas T1 - Inelastic and quasielastic neutron scattering experiments on microporous membranes fro green separation processes N2 - Polymers with intrinsic microporosity are promising candidates for the active separation layer in gas separation membranes. These polymers are characterized by a high permeability and reasonable permselectivity. The latter point is somehow surprising because for microporous systems a more Knudson-like diffusion is expected then a size dependent temperature activated sieving process. It was argued in the framework of a random gate model that molecular fluctuations on a time scale from ps to ns are responsible for the permselectivity. Here series of polymers of intrinsic microporosity (PIMs) as well as microporous polynorbornenes with bulky Si side groups and a rigid backbone are considered. The polymers have different microporosity characterized by high BET surface area values. First inelastic time-of-flight neutron scattering measurements were carried out to investigate the low frequency density of state (VDOS). The measured data show the characteristic low frequency excess contribution to the VDOS above the Debye sound wave level, generally known as the Boson peak in glass-forming materials. It was found that the frequency of the maximum position of the Boson peak correlates with the BET surface area value. Secondly elastic scans as well as quasielastic neutron scattering measurements by a combination of neutron time-of-flight and backscattering have been out. A low temperature relaxation process was found for both polymers. This process was assigned to the methyl group rotation. It was analysed in terms of a jump diffusion in a three-fold potential. The analysis of the dependence of the elastic incoherent structure factor on the scattering vector yields the number of methyl groups which might be immobilized. The neutron scattering experiments were accompanied by fast scanning calorimetry and broadband dielectric investigations as well as atomistic molecular dynamic simulations. T2 - Kolloquiumsvortrag an der Technischen Universität München CY - Garching, Germany DA - 20.11.2023 KW - Polymers with intrinsic microporosity PY - 2023 AN - OPUS4-59036 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Böhning, Martin A1 - Wald, Oliver A1 - Turky, Gamal A1 - Goering, Harald A1 - Brzezinka, Klaus-Werner A1 - Schartel, Bernhard A1 - Schönhals, Andreas T1 - Dielectric Relaxation and Gas Transport Properties in Polypropylene Based Nanocomposites T2 - ACS 2002 Biennial Symposium "Polymeric Nanomaterials" CY - Rohnert Park, CA, USA DA - 2002-11-17 PY - 2002 SP - 1(?) EP - 3(?) AN - OPUS4-2035 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Böhning, Martin A1 - Turky, Gamal A1 - Goering, Harald A1 - Wald, Oliver A1 - Schartel, Bernhard A1 - Schönhals, Andreas T1 - Polypropylene/Clay Nanocomposites - Dielectric Relaxation and Gas Transport Properties T2 - 2nd International Conference on Broadband Dielectric Spectroscopy and Its Applications CY - Leipzig, Germany DA - 2002-09-02 PY - 2002 AN - OPUS4-2037 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böhning, Martin A1 - Goering, Harald A1 - Hao, Ning A1 - Mach, Reinhard A1 - Oleszak, Franz A1 - Schönhals, Andreas T1 - Molecular Mobility and Gas Transport Properties of Polycarbonate-Based Nanocomposites PY - 2003 UR - http://www.ipme.ru/e-journals/RAMS/no_3503/bohning/bohning.html SN - 1606-5131 VL - 5 SP - 155 EP - 159 PB - Advanced Study Center CY - St. Petersburg AN - OPUS4-2884 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Böhning, Martin T1 - Dielectric and gas transport properties of polypropylene-clay nanocomposites T2 - DPG-Frühjahrstagung (Polymerphysik), Fachverband CPP, Themenkreis 3 CY - Regensburg, Germany DA - 2002-03-11 PY - 2002 AN - OPUS4-3623 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas A1 - Goering, Harald A1 - Böhning, Martin A1 - Fritz, Andreas A1 - Rübner, J. T1 - Structure Analysis of Polymeric Nanomaterials by Relaxation Spectroscopy T2 - Polydays 2002 CY - Berlin, Germany DA - 2002-09-30 PY - 2002 SP - 1(?) AN - OPUS4-2044 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Böhning, Martin T1 - Dielectric Relaxation and Gas Transport Properties in Polypropylene Based Nanocomposites T2 - ACS 2002 Biennial Symposium: Polymeric Nanomaterials CY - Rohnert Park, CA, USA DA - 2002-11-17 PY - 2002 AN - OPUS4-3622 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Goering, Harald A1 - Böhning, Martin A1 - Turky, Gamal A1 - Hao, Ning A1 - Schönhals, Andreas T1 - Molecular Dynamics in Polymer Nanocomposites T2 - Workshop "Glasübergang" CY - Rostock, Germany DA - 2002-12-16 PY - 2002 AN - OPUS4-2061 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Böhning, Martin A1 - Goering, Harald A1 - Hao, Ning A1 - Schönhals, Andreas T1 - Gas Transport in Polymer based Nanocomposite Systems T2 - Workshop "Glasübergang" CY - Rostock, Germany DA - 2002-12-16 PY - 2002 AN - OPUS4-2054 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Böhning, Martin A1 - Goering, Harald T1 - Herstellung und Charakterisierung von Nanopartikel/Polymer Composites T2 - BAM-Seminar der Abteilung VI "Funktion von Polymeren" CY - Berlin, BAM, Deutschland DA - 2002-09-19 PY - 2002 AN - OPUS4-2040 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hao, Ning A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Dielectric Properties of Nanocomposites Based on Polystyrene and Polyhedral Oligomeric Phenethyl-Silsesquioxanes N2 - Nanocomposites were prepared by solution blending of polyhedral oligomeric silsesquioxane with phenethyl substituents (PhenethylPOSS) into polystyrene (PS). The prepared materials were investigated by dielectric spectroscopy, differential scanning calorimetry (DSC), and density measurements. Additional FTIR investigations were carried out. Pure polystyrene shows two relaxation processes, an intermediate β*-process at lower and the α-relaxation at higher temperatures, the latter corresponding to segmental dynamics (dynamic glass transition). The molecular assignment of the β*-process needs further investigation. PhenethylPOSS can be incorporated into PS up to about 40 wt % without any indication of phase separation. With increasing PhenethylPOSS content, the α-relaxation of the composites shifts to lower temperatures and the loss peak broadens. Thus, the main effect of the nanofiller in the polystyrene matrix is to enhance the segmental dynamics, i.e., plasticization. The incorporation of approximately 40 wt % (approximately 5 mol %) PhenethylPOSS shifts the glass transition temperature Tg by 50 K to lower temperatures. The obtained results for polystyrene are discussed together with those reported recently for polycarbonate where a phase-separated morphology is observed for higher concentrations of PhenethylPOSS. The different behavior of PhenethylPOSS in polystyrene and polycarbonate is interpreted in terms of the different interaction of the phenyl rings within the POSS substituents with the phenyl rings of the polymers. For polystyrene, the interaction is stronger than for polycarbonate which probably leads to the enhanced miscibility of PhenethylPOSS into polystyrene. A detailed analysis of the temperature dependence of the dielectric relaxation strengths points also to additional interactions in the nanocomposites when compared to pure polystyrene. The broadening of the loss peak with increasing concentration is discussed in the framework of composition fluctuations. KW - Polyhedral oligomeric silsesquioxane (POSS) KW - Polymer-based nanocomposites KW - Broadband dielectric spectroscopy KW - Polystyrene PY - 2007 DO - https://doi.org/10.1021/ma071777g SN - 0024-9297 SN - 1520-5835 VL - 40 IS - 26 SP - 9672 EP - 9679 PB - American Chemical Society CY - Washington, DC AN - OPUS4-16492 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hao, Ning A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Structure Property Relationships of Polymeric Nanocomposites based on Polyhedral Oligomeric Silsesquioxanes PY - 2007 SN - 0743-0515 VL - 97 SP - 789 EP - 790 PB - Division of Polymeric Materials Science and Engineering, American Chemical Society CY - Washington, DC AN - OPUS4-15848 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Böhning, Martin A1 - Goering, Harald A1 - Hao, Ning A1 - Mach, Reinhard A1 - Schönhals, Andreas ED - Cassidy, P. T1 - Polycarbonate/SiC nanocomposites - Influence of nanoparticle dispersion on molecular mobility and gas transport T2 - 7th International Symposium on Polymers for Advanced Technologies CY - Fort Lauderdale, FL, USA DA - 2005-09-21 KW - Nanocomposites KW - Nanoparticles KW - Polycarbonates KW - Dielectric properties KW - Gas permeation PY - 2005 VL - 16 IS - 2-3 SP - 262 EP - 268 PB - Wiley CY - Chichester AN - OPUS4-7062 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Böhning, Martin A1 - Tidjani, Adams A1 - Wald, Oliver A1 - Turky, Gamal A1 - Goering, Harald A1 - Brzezinka, Klaus-Werner A1 - Schartel, Bernhard A1 - Schönhals, Andreas T1 - Polypropylene/Clay Nanocomposites - Gas Transport Characteristics and Molecular Mobility T2 - Polydays 2002 CY - Berlin, Germany DA - 2002-09-30 PY - 2002 SP - 1(?) EP - 2(?) AN - OPUS4-2038 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -