TY - JOUR A1 - Ghasem Zadeh Khorasani, Media A1 - Silbernagl, Dorothee A1 - Szymoniak, Paulina A1 - Hodoroaba, Vasile-Dan A1 - Sturm, Heinz T1 - The effect of boehmite nanoparticles (gamma‐AlOOH) on nanomechanical and thermomechanical properties correlated to crosslinking density of epoxy N2 - We show that complex physical and chemical interactions between boehmite nanoparticles and epoxy drastically affect matrix properties, which in the future will provide tuning of material properties for further optimization in applications from automotive to aerospace. We utilize intermodulation atomic force microscopy (ImAFM) for probing local stiffness of both particles and polymer matrix. Stiff particles are expected to increase total stiffness of nanocomposites and the stiffness of polymer should remain unchanged. However, ImAFM revealed that stiffness of matrix in epoxy/boehmite nanocomposite is significantly higher than unfilled epoxy. The stiffening effect of the boehmite on epoxy also depends on the particle concentration. To understand the mechanism behind property alteration induced by boehmite nanoparticles, network architecture is investigated using dynamic mechanical thermal analysis (DMTA). It was revealed that although with 15 wt% boehmite nanoparticles the modulus at glassy state increases, crosslinking density of epoxy for this composition is drastically low. KW - Crosslinking density KW - Epoxy KW - Intermodulation KW - Atomic force microscopy KW - Nanomechanical properties KW - Boehmite nanoparticles PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-476050 SN - 0032-3861 SN - 1873-2291 VL - 164 SP - 174 EP - 182 PB - Elsevier AN - OPUS4-47605 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leng, Jing A1 - Szymoniak, Paulina A1 - Kang, N.-J. A1 - Wang, D-Y A1 - Wurm, A. A1 - Schick, C. A1 - Schönhals, Andreas T1 - Influence of interfaces on the crystallization behavior and the rigid amorphous phase of poly(l-lactide)-based nanocomposites with different layered doubled hydroxides as nanofiller N2 - Based on the three-phase model of semi-crystalline polymers, we determined all phase fractions of the NiAl-LDH/PLLA nanocomposites in dependence on the concentration of the nanofiller. Moreover, the rigid amorphous fraction (RAF) was separated into the RAFcrystal and the RAFfiller unbiasedly. A detailed comparison to the related nanocomposite system MgAl-LDH/PLLA was made considering that Mg and Ni have different atomic weights. As a first result is was found that NiAl-LDH/PLLA displays a higher crystallization rate compared to MgAl-LDH/PLLA, which is related to the different morphologies of the two nanocomposite systems. For both systems RAFcrystal increases with increasing concentration of the nanofiller. This means in the case of the nanocomposite not each crystal produces the same amount of RAF, as often assumed. Also, RAFfiller increases with the concentration for both systems but in a different way. This is discussed considering again the different morphologies of both nanocomposites. KW - Polymer-based nanocomposites KW - Temperature modulated differential scanning calorimetry PY - 2019 U6 - https://doi.org/10.1016/j.polymer.2019.121929 VL - 184 SP - 121929 PB - Elesevier Ltd. AN - OPUS4-49557 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Szymoniak, Paulina A1 - Qu, Xintong A1 - Schönhals, Andreas T1 - Competition of mobilization and Immobilization Effects in Epox-Based Nanocomposites N2 - Two epoxy-based nanocomposites with different nanofillers (layered double hydroxide and boehmite) were investigated employing temperature modulated DSC, flash DSC and broadband dielectric spectroscopy. Detailed investigation on the molecular mobility of the two systems showed the effect of the fillers on the structure of the bulk epoxy matrix and the interface formed at the polymer/particle interface T2 - FOR 2021: Acting principles of Nano-Scaled Matrix Additives for Composite Structures CY - Berlin, Germany DA - 11.10.2019 KW - TMDSC KW - Nanocomposites KW - Rigid amorphous fraction KW - Boehmite KW - BDS PY - 2019 AN - OPUS4-49287 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Szymoniak, Paulina T1 - Flash DSC investigations on nanocomposites and electrospun fibers containing nanoparticles N2 - It was found for inorganic/polymer nanocomposites that a so-called Rigid Amorphous Phase (RAF) is formed in the interfacial region by adsorption of polymer segments onto the nanoparticles. The segmental dynamics of RAF is expected to be altered, as compared to the pure matrix, which might percolate into the entire system, affecting the overall nanocomposite properties. Here, the structure and molecular mobility of epoxy-based PNCs with different nanofillers (layered double hydroxide and boehmite) was studied by a combination of calorimetric and X-Ray scattering techniques. Temperature modulated DSC (TMDSC) showed that depending on the nanofiller, RAF can reach up to 40 wt % of the system or, on the contrary, the overall mobility of the matrix might increase due to the presence of particles. Such contrasting results, including the high amount of RAF, which was never shown before for epoxy-based PNCs, emphasize the importance of interfaces. Additionally, glass transition and glassy dynamics were investigated by a novel technique, Flash DSC (heating rates up to 10 kK/s) employed for the first time to a thermosetting system and electrospun fibers, which did not result in their degradation. It was used to study both the vitrification kinetics and glassy dynamics of the PNCs, for instance further confirming the presence of RAF and its impact on the overall material properties. T2 - 4th Mettler Toledo Flash DSC conference CY - Zurich, Switzerland DA - 25.11.2019 KW - Flash DSC KW - Nanocomposites KW - Rigid amorphous fraction KW - TMDSC KW - BDS KW - Boehmite KW - Electrospun fibers PY - 2019 AN - OPUS4-50067 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Szymoniak, Paulina A1 - Schönhals, Andreas T1 - Rigid amorphous phase in polymer nanocomposites as revealed by dielectric relaxation spectroscopy and fast scanning calorimetry N2 - For inorganic/polymer nanocomposites a so-called Rigid Amorphous Phase (RAF) is formed in the interfacial region by adsorption of polymer segments onto the nanoparticles. The segmental dynamics of RAF is expected to be altered, as compared to the pure matrix, which might percolate into the entire system, affecting the overall nanocomposite properties. A combination of two relaxation spectroscopy techniques (Broadband Dielectric Spectroscopy (BDS) and Specific Heat Spectroscopy (SHS) in a form of Temperature Modulated DSC (TMDSC)) as well as Fast Scanning Calorimetry (FSC) was employed to investigate the structure and molecular mobility of nanocomposites based on Epoxy and Layered Doubled Hydroxides with different nanoparticle content. First, BDS investigations proved the existence of a process, which is present only for nanocomposites, assigned to the dynamics of polymer segments within RAF. Second, the amount of RAF was quantified by analyzing the change of specific heat capacity step of nanocomposites, comparing to the pure material. Thirdly, the glass transition of nanocomposites was studied with FSC, applying high heating rates (500-10 000 K/s). Considering that all techniques probe essentially the same molecular process, an activation plot was constructed, delivering a complete picture of the molecular mobility and structure of the polymer nanocomposites including RAF. T2 - American Physical Society (APS) March Meeting 2019 CY - Boston, MA, USA DA - 04.03.2019 KW - Nanocomposites KW - Rigid amorphous fraction PY - 2019 AN - OPUS4-47564 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Szymoniak, Paulina T1 - Glass transition and glassy dynamics of thin polymer films and polymer nanocomposites N2 - Polymers at interfaces play a major role in a broad variety of applications ranging from engineering purposes (for instance polymer based nanocomposites) to high tech implications (for instance light emitting diodes). Here the glass transition and glassy dynamics is considered for epoxy-based nanocomposite with Layered Double Hydroxide nanofiller and for thin films of a misicble polymer blend of PVME/PS with thicknesses down to 7 nm. The materials are investigated by spectroscopic techniques (broadband and specific heat spectroscopy), as well as by fast scanning calorimetry and small- and wide-angle X-ray scattering. T2 - Seminarvortrag Columbia University CY - New York, USA DA - 11.03.2019 KW - Nanocomposites KW - Rigid amorphous fraction KW - Thin films KW - Interfaces PY - 2019 AN - OPUS4-47565 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Szymoniak, Paulina A1 - Schönhals, Andreas T1 - Rigid Amorphous Phase in Epoxy-based Nanocomposites as Revealed by Dielectric Spectroscopy and Fast Scanning Calorimetry N2 - For inorganic/polymer nanocomposites a so-called Rigid Amorphous Phase (RAF) is formed in the interfacial region by adsorption of polymer segments onto the nanoparticles. The segmental dynamics of RAF is expected to be altered, as compared to the pure matrix, which might percolate to the entire system, affecting the overall nanocomposite properties. A combination of two relaxation spectroscopy techniques (Broadband Dielectric Spectroscopy (BDS) and Temperature Modulated DSC (TMDSC)) as well as Fast Scanning Calorimetry (FSC) was employed to investigate the structure and molecular mobility of nanocomposites based on Epoxy and Layered Doubled Hydroxides with different nanoparticle content. First, BDS investigations proved the existence of a process, which is present only for nanocomposites, assigned to the dynamics of polymer segments within RAF. Second, the amount of RAF was quantified by analyzing the change of specific heat capacity step of nanocomposites, comparing to the pure material. Thirdly, the glass transition of nanocomposites was studied with FSC, applying high heating rates (0.5-10 kK/s). Considering that all techniques probe essentially the same molecular process, an activation plot was constructed, delivering a complete picture of the molecular mobility and structure of the polymer nanocomposites including RAF. T2 - DPG-Frühjahrstagung 2019 CY - Regensburg, Germany DA - 01.04.2019 KW - Rigid amorphous fraction KW - Nanocomposites PY - 2019 AN - OPUS4-47762 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Szymoniak, Paulina A1 - Schönhals, Andreas A1 - Madkour, Sherif T1 - Multiple Glassy Dynamics of an Asymmetric PVME/PS Blend Investigated by Broadband Dielectric and Specific Heat Spectroscopy N2 - Over the past decades research on the molecular dynamics of miscible polymer blends is of topical interest in the literature, to understand the segmental mobility of individual components, as it is affected by blending. In general, miscible polymer blends exhibit a complex dynamic behavior. For an A/B blend the relaxation times of component A and component B are affected by the spatial local compositional heterogeneity, present in binary systems on a microscopic level, regardless of the macroscopic homogeneity. Here, a combination of broadband dielectric and specific heat spectroscopy was employed to study the dynamically asymmetric PVME/PS blend with seven different compositions, focusing on samples with high PS contents. Considering that PS is dielectrically invisible, BDS is a powerful technique to study the response of PVME, as it is affected by PS segments. Here, three separate relaxation processes were found by dielectric investigations, related to confined or constrained PVME segments due to the spatial local compositional heterogeneities, which is in contrary to the previous literature findings [1]. Moreover, the dielectric data was compared with results obtained by specific heat spectroscopy, where a fourth relaxation process was found, due to the cooperative fluctuations of PVME and PS. [1] Colmenero, J., Arbe, A. Soft Matter, 2007, 3, 1474. T2 - DPG-Frühjahrstagung 2019 CY - Regensburg, Germany DA - 01.04.2019 KW - Specific heat spectroscopy KW - Polymer blends KW - Dielectric spectroscopy PY - 2019 AN - OPUS4-47764 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Gawek, Marcel A1 - Madkour, S. A1 - Schönhals, Andreas T1 - Confinement and localization effects revealed for thin films of the miscible blend Poly(vinyl methyl ether) / Polystyrene with a composition of 25/75 wt% N2 - Thin films (200-7nm) of the asymmetric polymer blend poly(vinyl methyl ether) (PVME)/polystyrene (PS) (25/75wt%) were investigated by broadband dielectric spectroscopy (BDS). Thicker samples ([Formula: see text]37 nm) were measured by crossed electrode capacitors (CEC), where the film is capped between Al-electrodes. For thinner films ([Formula: see text]37 nm) nanostructured capacitors (NSC) were employed, allowing one free surface in the film. The dielectric spectra of the thick films showed three relaxation processes ( [Formula: see text] -, [Formula: see text] - and [Formula: see text] -relaxation), like the bulk, related to PVME fluctuations in local spatial regions with different PS concentrations. The thickness dependence of the [Formula: see text] -process for films measured by CECs proved a spatially heterogeneous structure across the film with a PS-adsorption at the Al-electrodes. On the contrary, for the films measured by NSCs a PVME segregation at the free surface was found, resulting in faster dynamics, compared to the CECs. Moreover, for the thinnest films ([Formula: see text]26 nm) an additional relaxation process was detected. It was assigned to restricted fluctuations of PVME segments within the loosely bounded part of the adsorbed layer, proving that for NSCs a PVME enrichment takes place also at the polymer/substrate interface. KW - Thin polymer films KW - Broadband dielectric spectroscopy PY - 2019 U6 - https://doi.org/10.1140/epje/i2019-11870-3 SN - 1292-895X VL - 42 IS - 8 SP - 101, 1 EP - 11 PB - Springer AN - OPUS4-48651 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Li, Z. A1 - Wang, D.-Y. A1 - Schoenhals, Andreas T1 - Dielectric and flash DSC investigations on an epoxy based nanocomposite system with MgAl layered double hydroxide as nanofiller N2 - Nanocomposites based on MgAL layered double hydroxides (LDH) and an epoxy resin were prepared and investigated by a combination of complementary methods. As epoxy resin Bisphenol A diglycidyl ether (DGEBA) was used with Diethylenetriamine as curing agent. The LDH was modified with taurine, which acts as an additional crosslinking agent due to its amine groups. The epoxy resin was cured in a presence of the nanofiller, which was added to the system in various concentrations. X-ray scattering, by combination of SAXS and WAXS was used to characterize the morphology of the obtained nanocomposites. These investigations show that the filler is distributed in the matrix as small stacks of ca. 10 layers. The molecular dynamics of the system, as probe for structure, was investigated by broadband dielectric spectroscopy. In addition to the - and -relaxation (dynamic glass transition), characteristic for the unfilled materials, a further process was found which was assigned to localized fluctuations of segments physically adsorbed or chemically bonded to the nanoparticles. The dielectric -relaxation is shifted to higher temperatures for the nanocomposites in comparison to the pure material but depends weakly on the content of nanoparticles. Further, for the first time Flash DSC was employed to a thermosetting system to investigate the glass transition behavior of the nanocomposites. The heating rates were converted in to relaxation rates. For low concentrations of the nanofiller the thermal data overlap more or less with that of the pure epoxy. For higher concentrations the thermal data are shifted significantly to higher temperatures. This is discussed in terms the cooperativity approach to the glass transition. KW - Nanocomposites KW - Broadband dielectric spectroscopy KW - Flash DSC PY - 2019 U6 - https://doi.org/10.1016/j.tca.2019.01.010 SN - 0040-6031 VL - 677 SP - 151 EP - 161 PB - Elsevier AN - OPUS4-48218 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -