TY - JOUR A1 - Krebs, N. A1 - Demleitner, M. A1 - Albuquerque, R.Q. A1 - Schartel, Bernhard A1 - Ruckdäschel, H. T1 - Bayesian Optimization of flame-retardant performance in a high-Tg epoxy resin system N2 - Polymeric materials are widely used due to their mechanical properties and cost-effectiveness, but their inherent flammability requires effective flame-retardant additives to meet safety standards. Optimizing multicomponent flame-retardant formulations is challenging due to the vast experimental space. This study applies Bayesian Optimization (BO) to optimize flame-retardant formulations in high glass transition temperature (Tg) epoxy resins. Aluminum diethyl phosphinate (AlPi) was systematically combined with three synergists: zinc stannate (ZnSt), a silicone-based additive (DowSil), and low-melting glass frits (Ceepree). BO-guided experimental design expanded from 16 initial formulations to a total of 28, minimizing the Maximum Average Rate of Heat Emission (MARHE) under the constraint of Total Smoke Production (TSP) < 17 m2 using the epsilon-constraint method. BO revealed non-linear synergistic interactions: ZnSt significantly reduced smoke production while AlPi effectively lowered heat release. The optimized formulation (BO7) achieved the lowest MARHE (122 kW/m2) while maintaining acceptable smoke levels, establishing a new Pareto front. The results demonstrate the effectiveness of BO in accelerating the development of synergistic, halogen-free flame-retardant polymer systems, offering a scalable and sustainable approach to polymer formulation design. KW - Machine learning KW - Epoxy resin KW - Bayesian optimization KW - Flame retardancy KW - Cone calorimeter PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-641070 DO - https://doi.org/10.1016/j.commatsci.2025.114210 SN - 0927-0256 SN - 1879-0801 VL - 260 SP - 1 EP - 9 PB - Elsevier AN - OPUS4-64107 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fürst, Richard T1 - Behaviour of textile-reinforced concrete structures at elevated temperatures N2 - Presentation of the dissertation thesis about textile-reinforced concrete structures at elevated temperatures. The presentation at the conference was requested as a part of the award ceremony for the best dissertation thesis within the WTA Young Professional Awards. T2 - WTA Days 2024 CY - Brünn, Czech Republic DA - 14.03.2024 KW - Textile-reinforced concrete KW - Fire KW - Fire resistance KW - HPC KW - Epoxy resin PY - 2024 AN - OPUS4-60812 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Falkenhagen, Sandra F. T1 - black as hell, strong as death and sweet as love - pyrolyzed waste materials and cyclodextrins as effective filler in flame retarded epoxy composites N2 - Renewable alternatives for common thermoset resins are demanded to go for sustainability. The objective is to create a flame retarded epoxy resin from a commercial bio epoxy resin with halogen free inorganic and organic flame retardants, respectively. Alumina trihydrate, aluminum diethyl phosphinate, a DOPO-based phosphonamidate and ammonium polyphosphate seem to have promising performances. Properties are enhanced with different bio fillers: pyrolyzed cocoa shells and plant waste (provided by Otto A. Müller Recycling GmbH, thanks!), short fibers and nonwovens of the natural fiber kenaf, hydroxypropyl-ß-cyclodextrin and sulfobutylether-ß-cyclodextrin. Fire performance is investigated by cone calorimeter examinations, LOI and UL-94 ratings. Thermal analysis is given by TG-FTIR and DSC measurements. Combinations of flame retardants and bio-fillers lead to reduced PHRR and THR, reach V0 in UL-94 and have a significant increase in LOI of up to 37 vol.-%. 10 % ammonium polyphosphate with 10 % pyrolyzed cocoa shell performs best, builds a magnificent protective layer, and shows good intumescence. T2 - 3rd international conference on eco-friendly flame retardant additives and materials CY - Alès, France DA - 17.05.2022 KW - Epoxy resin KW - Flame retardant KW - Kenaf fiber KW - Pyrolyzed plant waste KW - Cyclodextrin PY - 2022 AN - OPUS4-54928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gleuwitz, F. Robert A1 - Battig, Alexander A1 - Schartel, Bernhard T1 - Tenebrio molitor Beetle as a “Nonvegan” Adjuvant to Flame Retardants in Tannic Acid-Based Epoxy Thermosets N2 - Material solutions that meet both circular bioeconomy policies and high technical requirements have become a matter of particular interest. In this work, a prospectively abundant proteinrich waste resource for the manufacturing of flame-retardant epoxy biocomposites, as well as for the synthesis of biobased flame retardants or adjuvants, is introduced. Different biomass fillers sourced from the cultivation of the mealworm beetle Tenebrio molitor are embedded in a bioepoxy resin cured with tannic acid and investigated regarding the fire performance of the thermosets. By means of spectroscopic and thermal analysis (attenuated total reflectance FTIR spectroscopy, thermogravimetric analysis-coupled FTIR spectroscopy, and differential scanning calorimetry), the influence of the biomass microparticles on the curing and thermal degradation behavior is evaluated. The final performance of the biocomposites is assessed based on fire testing methodology (limited oxygen index, UL-94, and cone calorimetry). Providing a high charring efficiency in the specific tannic acid-based epoxy matrix, the protein-rich adult beetle is further investigated in combination with commercial environmentally benign flame retardants in view of its potential as an adjuvant. The results highlight a char forming effect of nonvegan fillers in the presence of tannic acid, particularly during thermal decomposition, and point toward the potential of protein-based flame retardants from industrial insect rearing for future formulations. KW - Tannic acid KW - Flame retardancy KW - Sustainable KW - Epoxy resin KW - Insects PY - 2022 DO - https://doi.org/10.1021/acssuschemeng.2c00746 SN - 2168-0485 VL - 10 IS - 19 SP - 6313 EP - 6324 PB - ACS AN - OPUS4-54845 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Battig, Alexander A1 - Garfias González, Karla I. A1 - Schartel, Bernhard T1 - Valorizing “non-vegan” bio-fillers: Synergists for phosphorus flame retardants in epoxy resins N2 - Sustainable, biogenic flame retardant adjuvants for epoxy resins are receiving increased focus. Zoological products like insects, bone meal, and eggshells are available in large quantities, but remain uninvestigated as functional fillers to epoxy resins, although they are potential synergists to flame retardants. The efficacy and flame retardancy of “non-vegan” additives in combination with flame retardants is investigated and the fire behavior and thermal decomposition of bio-sourced epoxy resin composites is characterized. By comparing the fire performance of composites containing flame retardants or fillers at varying loadings (5, 10, and 20%), their role as synergists that enhance the function of organophosphorus flame retardants in bio-epoxy composites is identified and quantified. Peak heat release rates were 44% lower in composites containing both filler and flame retardant versus those containing only flame retardants, and fire loads were reduced by 44% versus the pure resin, highlighting the ability of “non-vegan” fillers to function as synergists. KW - Flame retardancy KW - Synergy KW - Bio-composite KW - Epoxy resin KW - Biogenic KW - Renewable PY - 2022 DO - https://doi.org/10.1016/j.polymdegradstab.2022.109875 SN - 0141-3910 VL - 198 SP - 109875 PB - Elsevier Ltd. AN - OPUS4-54438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fürst, Richard A1 - Vlach, T. A1 - Pokorny, M. A1 - Mozer, V. T1 - Study of Behavior of Textile-Reinforced Concrete with Epoxy Resin Matrix in Fire N2 - Textile-reinforced concrete is currently most frequently used for non-load–bearing structures, but there is a vision for also using it in load–bearing construction elements. In recent years, this construction material has been subjected to detailed examination. Different combinations of materials for potential use in textile-reinforced concrete have been described. These differ in the type of concrete mix and the composition of the textile reinforcement. The aim of this work is to test the application of a specific textile-reinforced concrete, consisting of high-performance concrete, textile reinforcement from carbon fibers and its epoxy resin matrix, at an elevated temperature. The combination of these materials makes it possible to produce subtle load–bearing structures with excellent mechanical properties. The critical issue is the behavior of these structures when exposed to fire. A series of medium-scale fire condition experiments were carried out with a temperature load based on the ISO 834 curve, followed up by mechanical tests. The aim of these experiments was to describe critical areas of textile-reinforced concrete in fire and to propose possible solutions. In an indicative fire experiment, experimental samples displayed massive spall of concrete layers, and interaction between materials was lost due to the low temperature resistance of the epoxy resin. Concurrently, the optimal quantity of polypropylene fibers was experimentally determined. This paper presents an experimental demonstration of the problematic aspects of textile-reinforced concrete and subsequent recommendations for future work with practical application in the design of load–bearing structures. KW - Textile-reinforced concrete KW - High-performance concrete KW - Carbon fibers KW - Epoxy resin KW - Load–bearing structures KW - Fire resistance PY - 2021 DO - https://doi.org/10.1007/s10694-021-01116-y SN - 1572-8099 SN - 0015-2684 SP - 1 EP - 22 PB - Springer AN - OPUS4-52712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Battig, Alexander A1 - Markwart, J. C. A1 - Wurm, F. R. A1 - Schartel, Bernhard T1 - Sulfur's role in the flame retardancy of thio-ether–linked hyperbranched polyphosphoesters in epoxy resins N2 - Hyperbranched polyphosphoesters are promising multifunctional flame retardants for epoxy resins. These polymers were prepared via thiol-ene polyaddition reactions. While key chemical transformations and modes of actions were elucidated, the role of sulfur in the chemical composition remains an open question. In this study, the FR-performance of a series of phosphorus-based flame retardant additives with and without sulfur (thioethers or sulfones) in their structure are compared. The successful synthesis of thio-ether or sulfone-containing variants is described and verified by 1H and 31P NMR, also FTIR and MALDI-TOF. A decomposition process is proposed from pyrolytic evolved gas analysis (TG-FTIR, Py-GC/MS), and flame retardancy effect on epoxy resins is investigated under pyrolytic conditions and via fire testing in the cone calorimeter. The presence of sulfur increased thermal stability of the flame retardants and introduced added condensed phase action. Likely, Sulfur radical generation plays a key role in the flame-retardant mode of action, and sulfones released incombustible SO2. The results highlight the multifunctionality of the hyperbranched polymer, which displays better fire performance than its low molar mass thio-ether analogue due to the presence of vinyl groups and higher stability than its monomer due to the presence of thio-ether groups. KW - Phosphoester KW - Hyperbranched KW - Sulfur KW - Thio-ether KW - Flame retardant KW - Epoxy resin PY - 2020 DO - https://doi.org/10.1016/j.eurpolymj.2019.109390 SN - 0014-3057 VL - 122 SP - 109390 PB - Elsevier Ltd. AN - OPUS4-50238 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Battig, Alexander T1 - Hyperbranched Polymeric Flame Retardants N2 - Most synthetic polymers have a high fire load, and as a result, they require flame retardants (FRs) to ensure their safe use. Phosphorus plays an important role in flame retardancy and has the potential to replace halogenated variants, which are assumed to be harmful to the environment and health. Among phosphorus-based FRs, there exists a trend towards polymeric, high molar mass molecules with complex molecular architectures. In this project, we synthesized a novel series of so-called phosphorus-based hyperbranched polymeric FRs and investigated their use as multifunctional additives to high-performance polymers, i.e. epoxy resins. By cleverly designing the chemical structure to contain varying amounts of P-O and P-N bonds, new insight into the chemical mechanism of flame retardancy was gained, and by comparing the hyperbranched polymers to their monomeric counterparts, a greater understanding of the role of complex architecture was won. This talk aims at presenting some of these results and proposes chemical mechanisms that illustrate what role these novel hyperbranched flame retardants play in molecular firefighting. T2 - AMI Fire Resistance in Plastics 2019 CY - Cologne, Germany DA - 03.12.2019 KW - Epoxy resin KW - Flame retardant KW - Hyperbranched polymers KW - Phosphoester KW - Phosphoramidate KW - Phosphoramide KW - Phosphorodiamidate KW - Pyrolysis PY - 2019 AN - OPUS4-50034 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Battig, Alexander A1 - Markwart, J. C. A1 - Wurm, F. R. A1 - Schartel, Bernhard T1 - Matrix matters: Hyperbranched flame retardants in aliphatic and aromatic epoxy resins N2 - We synthesized a library of phosphorus-based flame retardants (phosphates and phosphoramides of low and high molar mass) and investigated their behavior in two epoxy resins (one aliphatic and one aromatic). The pyrolytic and burning behavior of the two resins (via TGA, TG-FTIR, Hot stage FTIR, Py-GC/MS, PCFC, DSC, LOI, UL-94, Cone calorimeter) are analyzed and compared to the results of flame retardant (FR)-containing composites. A decomposition pathway incorporating the identified modes of action and known chemical mechanisms is proposed. The overlap of decomposition temperature (Tdec) ranges of matrix and FR determines the efficacy of the system. Low molar mass FRs strongly impact material properties like Tg but are very reactive, and high molar mass variants are more thermally stable. Varying PeO and PeN content of the FR affects decomposition, but the chemical structure of the matrix also guides FR behavior. Thus, phosphates afford lower fire load and heat release in aliphatic epoxy resins, and phosphoramides can act as additives in an aromatic matrix or a reactive FRs in aliphatic ones. The chemical structure and the structure-property relationship of both FR and matrix are central to FR performance and must be viewed not as two separate but as one codependent system. KW - Flame retardant KW - Phosphate KW - Phosphoramide KW - Epoxy resin KW - Hyperbranched polymer PY - 2019 DO - https://doi.org/10.1016/j.polymdegradstab.2019.108986 SN - 0141-3910 VL - 170 SP - 108986 PB - Elsevier Ltd. AN - OPUS4-49456 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prewitz, M. A1 - Gaber, M. A1 - Müller, Ralf A1 - Marotzke, C. A1 - Holtappels, Kai T1 - Polymer coated glass capillaries and structures for high-pressure hydrogen storage: Permeability and hydrogen tightness N2 - The hydrogen tightness of high-pressure hydrogen storage is a Basic criterion for long-term storage. The H2 permeation coefficients of epoxy resin and a glass lacquer were determined to enable the geometric optimization of a glass capillary storage. It was found that the curing conditions have no significant influence on the H2 permeation coefficient of resin. The H2 permeation coefficient of epoxy resin is only about three orders of Magnitude greater than that of borosilicate glass. This suggests that the initial pressure of 700 bar takes about 2.5 years to be halved in capillary array storage. Therefore, a high-pressure hydrogen storage tank based on glass capillaries is ideally suited for long-term storage in mobile applications. KW - Permeability KW - Glass capillaries KW - Coating KW - Hydrogen storage KW - Long-term calculation KW - Epoxy resin PY - 2018 DO - https://doi.org/10.1016/j.ijhydene.2017.12.092 SN - 0360-3199 VL - 43 IS - 11 SP - 5637 EP - 5644 PB - Elsevier AN - OPUS4-44327 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Qiu, Y. A1 - Wachtendorf, Volker A1 - Klack, Patrick A1 - Qian, L. A1 - Liu, Z. A1 - Schartel, Bernhard T1 - Improved flame retardancy by synergy between cyclotetrasiloxane and phosphaphenanthrene/triazine compounds in epoxy thermoset N2 - A siloxane compound (MVC) and a bi-group phosphaphenanthrene/triazine compound (TGD) were employed in epoxy thermosets to explore high-efficiency flame retardant systems. With only 1wt% MVC and 3wt% TGD, an epoxy thermoset passed UL 94 V-0 rating test and achieved a limiting oxygen index value of 34.0%, exhibiting an excellent flame retardant effect. The MVC/TGD system not only decreased the peak value of heat release rate and effective heat of combustion but also imparted an improved charring ability to thermosets, thereby outstandingly reducing the flammability of 1%MVC/3%TGD/EP. Compared with the fire performance of 4%TGD/EP and 4%MVC/EP, the MVC/TGD system showed an obvious flame retardant synergistic effect, mainly depending on the general improvement of flame inhibition, charring and barrier effects of the thermoset during combustion. Evolved gas analysis combinedwith condensed-phase pyrolysis product Analysis jointly revealed the details of the changed pyrolysis mode. KW - Flame retardant KW - Epoxy resin KW - Synergy KW - Siloxane KW - DOPO KW - Triazine PY - 2017 DO - https://doi.org/10.1002/pi.5466 SN - 0959-8103 SN - 1097-0126 VL - 66 IS - 12 SP - 1883 EP - 1890 PB - Wiley AN - OPUS4-42950 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schartel, Bernhard T1 - Flame and fire retardancy of polymer composites used in aviation N2 - The fire behaviour of carbon fibre (CF) reinforced polymers differs in comparison to polymers. Fibres behave often inert with respect to pyrolysis, they change the melt flow and dripping behaviour, the heat absorption and transfer, the amount and properties of the fire residue and so on. Flame and fire retardancy concepts are needed not only suitable for the different fire protection goals typical for each application, but also tailored for composites. This field is illuminated by examples taken from different projects carried out in the group of the author in the recent years. The examples target on different applications through achieving reduction in reaction to fire controlling the fire risks (flammability, heat release) in the beginning and development of a fire and investigating the fire stability, when a severe flame is directly applied (key property in fully developed fires). Approaches to halogen-free flame retardancy in CF reinforced thermosets are presented as well as building up a bench and an intermediate scale testing of composites in fire applying mechanical load (up to 1 MN compression) and direct flame exposure (180 kW/m2) simultaneously. Indeed, e.g. we have investigated the fire stability of stringer reinforced shell components taken out from the fuselage of an aircraft. The understanding of fire behaviour, fire resistance, and fire retardant modes of action in composites is a promising basis for target-oriented development. The role of flame inhibition, charring, and protective layer formation is discussed. Successful concepts are presented for fire retardancy tailored for different application as well as general guidelines for future development. Different phosphorus flame retardants are proposed to achieve halogen-free flame retardancy with respect to ignition and developing fires. Different protective approaches are sketched for addressing the fire stability of composites that is the most important fire risk for the fire resistance in structural applications. T2 - 7th EASN International Conference on Innovation in European Aeronautics Research CY - Warsaw, Poland DA - 26.09.2017 KW - Composite in Fire KW - Carbon fibre reinforced composite KW - Epoxy resin KW - Stringer reinforced shells KW - Fire stability KW - Flammability KW - Sandwich panels KW - Intumescence KW - Pyrolysis KW - Flame retardant PY - 2017 AN - OPUS4-42433 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, R. T1 - Experimentally calibrated modeling technique for the cross linking mechanism of epoxy resin and its influence on mechanical properties N2 - Epoxy resins are one of the first choices for structural adhesives and are widely used in combination with fibers as fiber reinforced plastics (FRP). The mechanical properties are the result of the complex chemical network structure that is generated by the thermally catalyzed cross linking reaction. Numerical simulations on the atomistic length scale are appropriate tools to understand and improve the mechanical properties and its mechanisms of epoxy resins. This leads to the necessity of a model generation procedure that covers the characteristic cross linking mechanisms of epoxy resins and is able to generate a realistic representation of the network structure. Research in the field of Molecular Dynamic based curing kinematics of polymers has led to cross linking procedures that are based on the main chemical curing reaction and can produce models, whose mechanical properties are in agreement with experimental values. Nevertheless an assessment of the realism of these cross linking procedures is difficult, since various complex aspects, such as the influence of the activator molecules or catalyzing chemical reactions may be important, but are hard to characterize. By using the method of in situ near-infrared spectroscopy (NIR) the time and temperature evolution of the reactive groups, epoxy and either amine or anhydrite curing groups, can be measured. It has been shown that this method is well suited for analyzing the curing process and to characterize the fully hardened epoxy resin. Thus NIR measurements of the cross linking kinetics of epoxy resins give a valuable insight in the curing process that can be used to calibrate and assess numerical approaches of the cross linking procedure. A modeling technique for the curing kinematics of epoxy resins is presented, that is able to realistically represent the cross linking mechanism and generate simulation models with characteristics in good agreement with experimentally analyzed cured epoxy resins. This is achieved by calibrating the cross linking parameters and is shown by a comparison of both, the cross linking procedure and the resulting network structure, with experimental results of NIR measurements. The modeling approach is incorporated in the Molecular Dynamic Finite Element Method (MDFEM) framework and implements a step by step molecular network build-up. This allows to perform MDFEM equilibrium iterations during the curing procedure in order to create realistic and well equilibrated simulation models. Furthermore MDFEM simulations of tensile tests are presented to evaluate the influence of the network structure on the elastic mechanical properties. These numerical tests also illustrate the need for accurate models when deriving material properties from atomistic length scale simulations. T2 - ICCS 20 CY - Paris, France DA - 04.09.2017 KW - Epoxy resin KW - NIR spectroscopy KW - Mechanics PY - 2017 AN - OPUS4-42416 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Battig, Alexander T1 - Hyperbranched Polyphosphoesters, -di/amidates and –amides as Novel Flame Retardants for Epoxy Resins: Understanding the Role of Chemical Composition N2 - The use of phosphorus-containing flame retardants as a viable alternative to their widely used halogen-containing counterparts has been the source of much recent research. As the search for an effective flame retardant for specific polymeric systems continues, a new class of flame retardants have shown promising results, namely hyperbranched polyphosphoesters and their derivatives. These macromolecules promise to combine the effects of complex, hyperbranched structures with the flame retarding effects of phosphorus, enabling a high miscibility and processability, as well as a lower impact on glass transition temperature and decreased diffusion from the polymer matrix. These and other functions enable them to act as multifunctional additives. In recent times, phosphorus-based hyperbranched materials and their efficacy as flame retardants have been described in literature. Often, the inclusion of nitrogen atoms into the chemical surrounding of phosphorus has lead to reports of increased flame retarding performance through synergistic effects. However, a comprehensive study of the relationship between nitrogen and phosphorus in hyperbranched polymers is lacking. The aim of this work is to determine the efficacy of novel, phosphorus-based hyperbranched polymers compared to other, commercially available, previously studied flame retardants and to investigate the molecular flame retarding mechanism of these complex structured macromolecules. Among one of the key aspects here is the modification of the O:N ratio of the phosphorus-containing repeating units of these hyperbranched polymers. The newly described synthesis route yields trifunctional monomers of the desired composition, which undergo an A2+B3-type polymerization via radical thiol-ene reactions, producing polyphosphoesters, -amidates, -diamidates, or -amides, respectively. By precisely tailoring the nitrogen and oxygen ratio in the chemical surrounding of phosphorus, a more comprehensive picture of the structure-property relationship of these materials may be gained. Furthermore, by adjusting the aromaticity of the hydrocarbon moieties in these trifunctional monomers, an optimization of flame retarding properties, such as increased charring, is aimed to be achieved. Additionally, the trifunctional monomers themselves act as low molecular weight fire retardants; therefore, by comparing the performance of these monomers to their high molecular weight, hyperbranched, polymeric counterparts, an understanding of the role of molecular architecture in designing a more effective flame retardant can be gained. Finally, several epoxy resin matrices, common in high-tech industrial applications, are investigated in the interest of comprehending the interaction between these novel hyperbranched flame retardant additives and their surrounding polymeric matrix. In order to determine the flame retardancy mechanism of these materials, a multi-methodological approach is selected, thus offering a high volume of correlating data. Using Fourier-transform infrared spectroscopy (FTIR) coupled with thermogravimetric analysis (TGA), as well as pyrolysis combustion flow calorimetry (PCFC), provides evidence of mass loss processes, their respective decomposition products, and the heat released by volatiles in the gas phase during pyrolysis, while hot-stage FTIR offers information of the decomposition products occurring in the condensed phase. Limiting oxygen index (LOI) and UL-94 help to quantify and categorize the materials’ flammability, while the use of a cone calorimeter offers valuable insight into the fire behavior in forced flaming conditions, providing heat release rates, smoke and CO/CO2 production, amount of residue, and other important indices. Finally, the use of differential scanning calorimetry (DSC) provides information of material properties such as glass transition temperatures, and the implementation of blooming tests serves to examine the reduction of molecular mobility in the matrix. By varying the architecture of the flame retardants – in the O:N ratio of the chemical surrounding of phosphorus and in the aromatic composition of the monomers’ hydrocarbon moieties – and by comparing low versus high molecular weight species in varied epoxy resin matrices, as well as through the use of a multi-methodological approach, new insight into the use and the mode of action of these components as flame retardants for modern materials can be won. T2 - FRPM 2017, 16th European Meeting on Fire Retardant Polymeric Materials CY - Manchester, UK DA - 03.07.2017 KW - Hyperbranched polymer KW - Phosphoester KW - Phosphor(di)amidate KW - Phosphoramide KW - Flame retardant KW - Epoxy resin PY - 2017 AN - OPUS4-40948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rabe, Sebastian A1 - Chuenban, Yuttapong A1 - Schartel, Bernhard T1 - Exploring the Modes of Action of Phosphorus-Based Flame Retardants in Polymeric Systems N2 - Phosphorus-based flame retardants were incorporated into different, easily preparable matrices, such as polymeric thermoset resins and paraffin as a proposed model for polyolefins and investigated for their flame retardancy performance. The favored mode of action of each flame retardant was identified in each respective system and at each respective concentration. Thermogravimetric analysis was used in combination with infrared spectroscopy of the evolved gas to determine the pyrolysis behavior, residue formation and the release of phosphorus species. Forced flaming tests in the cone calorimeter provided insight into burning behavior and macroscopic residue effects. The results were put into relation to the phosphorus content to reveal correlations between phosphorus concentration in the gas phase and flame inhibition performance, as well as phosphorus concentration in the residue and condensed phase activity. Total heat evolved (fire load) and peak heat release rate were calculated based on changes in the effective heat of combustion and residue, and then compared with the measured values to address the modes of action of the flame retardants quantitatively. The quantification of flame inhibition, charring, and the protective layer effect measure the non-linear flame retardancy effects as functions of the phosphorus concentration. Overall, this screening approach using easily preparable polymer systems provides great insight into the effect of phosphorus in different flame retarded polymers, with regard to polymer structure, phosphorus concentration, and phosphorus species. KW - Flame retardants KW - Flame inhibition KW - Cone calorimeter KW - Aluminum diethyl phosphinate KW - Polyester KW - PMMA KW - Epoxy resin KW - Red phosphorus KW - BDP PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-402731 DO - https://doi.org/10.3390/ma10050455 SN - 1996-1944 VL - 10 IS - 5 SP - 455, 1 EP - 455, 23 PB - MDPI AN - OPUS4-40273 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sut, Aleksandra A1 - Greiser, Sebastian A1 - Jäger, Christian A1 - Schartel, Bernhard T1 - Synergy in flame-retarded epoxy resin - Identification of chemical interactions by solid-state NMR N2 - The potential synergists aluminium diethylphosphinate (AlPi), boehmite (AlO(OH)) and melamine polyphosphate (MPP) were compared in flame-retardant epoxy resin (EP)/melamine poly(magnesium phosphate) (S600). The pyrolysis, the fire behaviour as well as the chemical interactions in the gas and condensed phases were investigated by various methods. Flammability was investigated by cone calorimeter and oxygen index (OI). The thermal and thermo-oxidative decomposition were studied by thermogravimetric analysis coupled with FTIR spectrometer. The special focus was on the Investigation of structural changes in the condensed phase via solid-state NMR of 27Al and 31P nuclei. By the comparison of epoxy resin with only one additive or with S600 in combination with AlPi, AlO(OH) or MPP, it was possible to calculate the synergy index. The best performance in terms of fire behaviour was observed for EP/S600/MPP with a PHRR (Peak heat release rate) of 208 kW m-2 due to slight synergy. In the case of THE (total heat evolved), clear synergy occurred for EP/S600/AlPi and EP/S600/AlO(OH). By solid-state NMR, different phosphates and aluminates were identified, indicating the chemical interactions between S600 and AlPi, AlO(OH) or MPP. The systematic multi-methodical approach yielded insight into the synergistic effects in the flame-retarded epoxy resin. KW - Synergy KW - Epoxy resin KW - Flame retardancy KW - Melamine poly(magnesium phosphate) KW - Solid-state NMR PY - 2017 DO - https://doi.org/10.1007/s10973-016-5934-4 SN - 1388-6150 SN - 1588-2926 VL - 128 IS - 1 SP - 141 EP - 153 PB - Springer AN - OPUS4-39298 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Erdmann, Maren A1 - Trappe, Volker A1 - Sturm, Heinz A1 - Braun, Ulrike A1 - Dümichen, Erik T1 - Cure conversion of structural epoxies by cure state analysis and in situ cure kinetics using nondestructive NIR spectroscopy N2 - Non-isothermal heating rate kinetics was applied to two epoxy resin systems. In situ near-infrared (NIR) measurements were taken with a heatable NIR cell which allowed the cure to be monitored by characteristic absorption bands. An autocatalyzed reaction of the nth order was shown to describe the epoxy conversion curves. Differential Scanning Calorimetry (DSC) was used as a complementary method. The kinetic models developed by both NIR and DSC are in good accordance with experimental epoxy conversion in the in situ NIR setup for single and multiple cure temperature ramps. A linear calibration curve of the characteristic absorption bands of epoxy normalized to aromatic vibrations was introduced. The curing degree of structural epoxies that were cured according to an industrial temperature cure profile was determined by NIR using the calibration curve. The epoxy conversions of the structural components showed good agreement with the experimental in situ NIR. Several degrees of cure for structural specimens were evaluated by NIR and residual reaction enthalpy by DSC. We present the non-destructive NIR spectroscopy as an alternative to determine fast and non-destructive epoxy conversion, particularly suitable for high degrees of cure on structural components. KW - Epoxy resin KW - Curing kinetics KW - In situ near-infrared (NIR) spectroscopy KW - Differential scanning calorimetry (DSC) PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0040603117300205 DO - https://doi.org/10.1016/j.tca.2017.01.010 SN - 0040-6031 SN - 1872-762X VL - 650 SP - 8 EP - 17 PB - Elsevier B.V. AN - OPUS4-39123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Martins, M. S. S. A1 - Schartel, Bernhard A1 - Magalhães, F. D. A1 - Pereira, C. M. C. T1 - The effect of traditional flame retardants, nanoclays and carbon nanotubes in the fire performance of epoxy resin composites N2 - The effectiveness of distinct fillers, from micro to nano-size scaled, on the fire behaviour of an epoxy resin and its carbon fibre reinforced composites was assessed by cone calorimetry. The performance was compared not only regarding the reaction to fire performance, but also in terms of thermal stability, glass transition temperature and microstructure. Regarding the fire reaction behaviour of nanofilled epoxy resin, anionic nanoclays and thermally oxidized carbon nanotubes showed the best results, in agreement with more compact chars formed on the surface of the burning polymer. For carbon fibre reinforced composite plates, the cone calorimeter results of modified resin samples did not show significant improvements on the heat release rate curves. Poorly dispersed fillers in the resin additionally caused reductions on the glass transition temperature of the composite materials. KW - Epoxy resin KW - Carbon fibre reinforced composite KW - Nanoclays KW - Carbon nanotubes KW - Flame retardants PY - 2017 DO - https://doi.org/10.1002/fam.2370 SN - 1099-1018 SN - 0308-0501 VL - 41 IS - 2 SP - 111 EP - 130 PB - Wiley & Sons, Ltd. AN - OPUS4-39085 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tang, S. A1 - Wachtendorf, Volker A1 - Klack, Patrick A1 - Qian, Lijun A1 - Dong, Y. A1 - Schartel, Bernhard T1 - Enhanced flame-retardant effect of montmorillonite/phosphaphenanthrene compound in an epoxy thermoset N2 - A phosphaphenanthrene and triazinetrione group containing flame retardant (TAD) is combined with organically modified montmorillonite (OMMT) in epoxy resin thermosets (EP) to improve the performance of the flame-retardant system. When only 1 wt% OMMT/4 wt% TAD is introduced into the EP, the limited oxygen index (LOI) rises from 26% to 36.9% and a V-0 rating is achieved in a UL 94 test. The decomposition and pyrolysis products in the gas phase and condensed phase were characterized using thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR). The influence on the decomposition of EP, such as the increase in char yield, is limited with the incorporation of OMMT; a large amount of the phosphorus is released into the gas phase. The flame-retardant effect evaluation based on cone calorimeter data testified that OMMT improves the protective-barrier effect of the fire residue of OMMT/TAD/EP on the macroscopic scale, while TAD mainly causes flame inhibition. The fire residues showed a corresponding macroscopic appearance (digital photo) and microstructure (scanning electron microscope [SEM] results). The protective barrier effect of OMMT and the flame-inhibition effect of TAD combined to exert a superior flame-retardant effect, resulting in sufficient flame-retardant performance of OMMT/TAD/EP KW - Flame retardant KW - Nanocomposite KW - DOPO KW - Thermoset KW - Epoxy resin KW - TG-FTIR PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-388865 DO - https://doi.org/10.1039/c6ra25070j SN - 2046-2069 VL - 7 IS - 2 SP - 720 EP - 728 AN - OPUS4-38886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Marotzke, Christian T1 - Fracture on microscale of fiber reinforced composites N2 - Failure of composite materials is initiated by fracture processes on microscale, especially by interfacial debonding. Failure processes taking place on microscale are studied by single fiber experiments. This is, single fibers embedded in tensile specimen are loaded under various off-axis angles. Starting at microdefects interface cracks propagate circumferentially as well as longitudinally, depending on the loading angle. In addition, finite element simulations of interfacial crack propagation around single fibers as well as fibers embedded in a hexagonal composite are shown based on linear elastic fracture mechanics. The course of the energy release rate is given in dependence of the fiber volume fraction. T2 - Seminar CY - Imperial College, London, UK DA - 12.10.2016 KW - Composites KW - Fracture surfaces KW - Micromechanics KW - Epoxy resin PY - 2016 AN - OPUS4-37853 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -