TY - CONF A1 - Battig, Alexander T1 - Multifunctional Graphene in Flame Retarded Polybutadiene/ Chloroprene/ Carbon Black Composites N2 - Multilayer graphene is investigated as a multifunctional nanofiller to polybutadiene/ chloroprene rubbers (BR/CR) that partially substitutes carbon black (CB) and aluminum trihydroxide (ATH). Loadings of only 3 parts per hundred rubber (phr) MLG replaced 15 phr of CB and/or 3 phr of ATH in BR/CR nanocomposites. Mechanical and fire behavior were investigated, and results point to improved rheological, curing and mechanical properties of MLG-containing rubber composites. T2 - 18th European Meeting on Fire Retardant Polymeric Materials, FRPM21 CY - Budapest, Hungary DA - 29.08.2021 KW - Graphene KW - Rubber KW - Fire Retardant KW - Nanofiller KW - Nanocomposite KW - ATH PY - 2021 AN - OPUS4-53202 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Schartel, Bernhard ED - Hu, Y. ED - Wang, X. T1 - Influence of the Size and Dispersion State of Two-Dimensional Nanomaterials on the Fire Safety of Polymers N2 - Only the nano-scaled structure of the nanocomposite and the dispersion of nanoparticles within the polymer matrix harbor multifunctional potential including superior fire retardancy. Thus, this chapter focuses on the dispersion of nanoplates, based mainly on studies of layered silicates and graphene/graphene-related nanoplates. The nanostructure and properties of the nanocomposites are dependent mainly on thermodynamic and kinetic factors during preparation. Improving nano-dispersion often directly improves flame retardancy. Therefore, the modification of the nanoplates as well as the preparation of nanocomposites becomes very important to control this dispersion. The dispersion of nanoplates functions as a prerequisite for the formation of an efficient protective layer, changing the melt flow and dripping behavior, or the improvement of the char properties. KW - Nanocomposite KW - Flame retardancy KW - 2D nanoparticle KW - Exfoliation KW - Dispersion KW - Flammability PY - 2023 SN - 978-1-032-35268-8 SN - 978-1-032-35502-3 SN - 978-1-003-32715-8 DO - https://doi.org/10.1201/9781003327158-2 SP - 23 EP - 58 PB - CRC Press CY - Boca Raton AN - OPUS4-58290 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Emamverdi, Farnaz T1 - Molecular mobility and gas transport properties of mixed matrix membranes based on PIM-1 and POF fillers N2 - Especially now in times of the energy revolution, the demand for energy-efficient separation processes promotes the advancement of new high-performance materials for use as highly selective separation membranes. Polymers with intrinsic microporosity (PIMs) are of high interest in the field of gas separation membranes. Currently the application of PIMs for membrane technology is still restrained by their strong tendency to physical aging involving a significant loss of their good gas separation properties. Physical aging phenomenon is related to the molecular mobility of PIMs which was investigated by broadband dielectric spectroscopy (BDS) previously [1]. In this work, covalent phosphinine-based framework (Eto-CPSF) was used as a nanofiller (0-10 wt %) in a PIM-1 matrix to potentially enhance the gas transport properties and prevent physical aging. Since molecular mobility is a fundamental parameter determining gas transport as well as physical aging in such a material, our study includes dielectric investigations by BDS of pure PIM-1 and PIM-1/Eto-CPSF mixed matrix membranes to establish a correlation between molecular mobility and gas transport properties. In addition, gas permeability was determined by the time-lag method (0-10 bar pressure) at 35 °C for N2, O2, CH4 and CO2 for all MMMs. The dielectric behavior of the polymeric films and their response upon heating were measured by isothermal frequency scans during different heating/cooling cycles in a broad temperature range up to 250 °C. Multiple dielectric processes following Arrhenius behavior were observed. Local fluctuations, Maxwell-Wagner-Sillars (MWS) polarization and structural relaxations were discussed correlating to structural-properties of PIM-1. As main result for MMMs, the permeability of PIM-1 for CH4 and CO2 gases were increased significantly with only 5 wt% of nanofiller within the polymer matrix. However, this is not observed for Eto-CPSF concentrations higher than ca. 7 wt% probably due to a microphase separated morphology of the nanocomposite system. Furthermore, the permselectivity of membranes for pair gases O2/N2 and CO2/N2 show enhancement up to a concentration of about 7 wt% Eto-CPSF filler. T2 - 11th BDS conference CY - San Sebastian, Spain DA - 04.09.2022 KW - Gas transport KW - BDS KW - Mixed Matrix Membrane KW - Nanocomposite PY - 2022 AN - OPUS4-55752 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schartel, Bernhard T1 - Multifunctional Elastomer/Graphene Nanocomposites N2 - A few layer/multilayer graphene (MLG) with a specific surface area of BET=250 m2/g is proposed as an efficient multifunctional nanofiller for rubbers. The preparation method, i.e., ultrasonically-assisted solution mixing of master batches followed by two-roll milling, strongly influences the dispersion in the elastomeric matrix and is fundamental for the final properties. When homogenously dispersed, single stacks of only approximately 10 graphene sheets, with an aspect ratio of 34, work at low loadings, enabling the replacement of large amounts of carbon black (CB), an increase in efficiency, and a reduction in filler load. The appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing, gas barrier properties, electrical and thermal conductivity, as well as mechanical properties of different rubbers, as shown for chlorine-Isobutylene-Isoprene rubber (CIIR), nitrile-butadiene rubber (NBR), natural rubber (NR), and styrene-butadiene rubber (SBR). 3 phr of MLG tripled the Young’s modulus of CIIR, an effect equivalent to 20 phr of CB. The stronger interactions between MLG and NR or SBR also resulted in a reduction in the elongation at break by 20% and 50%, respectively, while the same parameter was hardly changed for CIIR/MLG and NBR/MLG. CIIR/MLG and NBR/MLG were stiffer but just as defomable than CIIR and NBR. The strong reinforcing effect of 3 phr MLG was confirmed by the increase of greater than 10 Shore A in hardness. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards flammability, the latter shown by the reduction in heat release rate in the cone calorimeter. We investigated MLG also as a synergist for reducing the aluminium trihydrate loading in flame retardant hydrogenated acrylonitrile-butadiene (HNBR), polybutadiene chloroprene (BR/CR), and chlorosulfonated polyethylene rubber(CSM). The higher the nanofiller concentration is, the greater the improvement in the properties. For instance, the permeability decreased by 30% at 3 phr of MLG, 50% at 5 phr and 60% at 10 phr, respectively. Moreover, the MLG nanocomposites improve stability of mechanical properties against the effects of weathering. In key experiments an increase in UV-absorption and a pronounced radical scavenging were proved as stabilizing mechanisms. In a nutshell, MLG is an efficient multifunctional nanofiller ready to be used for innovative rubber development. T2 - 19th European Polymer Congress, EPF 2022 CY - Prague, Czech Republic DA - 26.06.2022 KW - Graphene KW - Nanocomposite KW - Rubber KW - Elastomer PY - 2022 AN - OPUS4-55196 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strommer, Bettina A1 - Schulze, Dietmar A1 - Schartel, Bernhard A1 - Böhning, Martin T1 - Networking Skills: The Effect of Graphene on the Crosslinking of Natural Rubber Nanocomposites with Sulfur and Peroxide Systems N2 - Tailored crosslinking in elastomers is crucial for their technical applications. The incorporation of nanoparticles with high surface-to-volume ratios not only leads to the formation of physical networks and influences the ultimate performance of nanocomposites, but it also affects the chemical crosslinking reactions. The influence of few-layer graphene (FLG) on the crosslinking behavior of natural rubber is investigated. Four different curing systems, two sulfur-based with different accelerator-to-sulfur ratios, and two peroxide-based with different peroxide concentrations, are combined with different FLG contents. Using differential scanning calorimetry (DSC), vulcametry (MDR) and swelling measurements, the results show an accelerating effect of FLG on the kinetics of the sulfur-based curing systems, with an exothermic reaction peak in DSC shifted to lower temperatures and lower scorch and curing times in the MDR. While a higher accelerator-to-sulfur ratio in combination with FLG leads to reduced crosslinking densities, the peroxide crosslinkers are hardly affected by the presence of FLG. The good agreement of crosslink densities obtained from the swelling behavior confirms the suitability of vulcameter measurements for monitoring the complex vulcanization process of such nanocomposite systems in a simple and efficient way. The reinforcing effect of FLG shows the highest relative improvements in weakly crosslinked nanocomposites. KW - Nanocomposite KW - Elastomers KW - Graphene KW - Crosslinking KW - Network KW - Rubber KW - Vulcanization PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-560409 DO - https://doi.org/10.3390/polym14204363 VL - 14 IS - 20 PB - MDPI AN - OPUS4-56040 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strommer, Bettina A1 - Schulze, Dietmar A1 - Schartel, Bernhard A1 - Böhning, Martin T1 - The quantification of anisotropy in graphene/natural rubber nanocomposites: Evaluation of the aspect ratio, concentration, and crosslinking N2 - In the processing of nanocomposites, high shear stresses at elevated tempera-tures orient two-dimensional nanoparticles like graphene. This orientationleads to anisotropic mechanical, thermal or barrier properties of the nanocom-posite. This anisotropy is addressed in this study by comparing graphene (few-layer graphene, FLG) with a nanoscaled carbon black (nCB) at a filler contentof 3 phr, by varying the vulcanization, and by comparing different FLG con-tents. Transmission electron microscopy gives insight into the qualitative ori-entation in the nanocomposite with FLG or nCB. The storage moduli paralleland normal to the orientation reveal the direction dependency of reinforce-ment through dynamic mechanical analysis (DMA). Dimensional swellingmeasurements show a restriction of the expansion parallel to the FLG orienta-tion, and an increased expansion normal to the orientation. The vulcanizationsystem and crosslinking determine the respective level of property values, andhigher crosslinking densities increase the anisotropy in DMA resulting invalues of up to 2.9 for the quantified anisotropy factor. With increasing FLGcontent, the anisotropy increases. A comparison of the results reveals swellingmeasurements as the most suitable method for the determination of anisot-ropy. Compared to recent literature, the presented processing induces higheranisotropy, leading to higher reinforcing effects in the direction of orientation KW - Natural rubber KW - Graphene KW - Nanocomposite KW - Mechanical properties KW - Swelling PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-571522 DO - https://doi.org/10.1002/app.53753 SN - 1097-4628 VL - 140 IS - 16 SP - 1 EP - 15 PB - Wiley online library CY - Hoboken, New Jersey (USA) AN - OPUS4-57152 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -