BAM-Publica - Publikationsserver der Bundesanstalt für Materialforschung und -prüfung
Not a member yet
58839 research outputs found
Sort by
Der digitale Produktpass für Bauprodukte
No full textDer mit der Revidsion der Bauproduktenverordnung eingeführte digitale Produktpass für Bauprodukte wird erläutert. Speziell werden Funktion, Interaktion mit dem Register der Ökodesign-Verordnung und zukünftige Normungsaufgaben dargestellt
Limitations of SEC: Strategies for Improved Regulatory Polymer Analysis
No full textPolymers, composed of repeating units called monomers, exhibit a diverse range of properties, with molecular weight distribution (MWD) being particularly important for regulatory risk assessments. Size exclusion chromatography (SEC), or gel permeation chromatography (GPC), is the primary technique for MWD characterization, as detailed in OECD guidelines 118 and 119, along with DIN and ISO standards. However, SEC faces significant shortcomings that complicate the accurate determination of MWD and oligomer content. These limitations include the insolubility of certain polymers, crosslinking, and ultra-high molecular weight characteristics, which can exceed SEC's separation capabilities. The presence of salts or modifiers can further interfere with oligomer content determination, and the availability of appropriate SEC columns and calibration standards limits comparability across laboratories.
To enhance SEC's reliability and applicability within regulatory frameworks, innovative methods and strategies are essential. Proposed solutions involve new sample preparation techniques, advanced data interpretation methods, and the establishment of standardized methodologies to promote harmonization. This is especially crucial in light of the expected Polymer REACh (PREACh) legislation, which aims to regulate polymer registration and risk assessment within the European market.
Given the anticipated complexity of the registration process, which requires extensive data generation, proactive strategies are needed to address SEC's challenges. Currently, there are no viable alternatives for oligomer content determination, and the unique properties of polymers often necessitate tailored analytical approaches. Without new methodologies and guidelines, the polymer registration process could become burdensome and costly, jeopardizing important products and markets in the EU.
Key areas for improvement include extending existing norms to cover a broader range of solvents, addressing high error margins in oligomer content determination, establishing harmonized approaches for dealing with side components, and providing clarity on measuring partially soluble polymers. In conclusion, addressing SEC's limitations through the development of comprehensive guidelines and harmonization is critical for ensuring accurate and efficient polymer analysis, ultimately facilitating smoother registration processes
Description of a measurement setup for LLB exposures in dynamic situations using high-resolution measurement technology
No full textIn order to gain an understanding of the Low Level Blast (LLB) exposure of soldiers when using weapon systems, it is necessary to characterize these weapon systems with regard to their overpressure effect [1]. Carrying out static measurements of weapon systems in the rough terrain of firing ranges and training areas poses a challenge for sensitive measurement technology. Furthermore, soldiers are often exposed to LLB in dynamic situations [2]. Therefore, commercially available blast gauges are often used, which, however, are not sufficient for high-resolution measurement of overpressure exposures with academic requirements due to their intended use [3]. Static measurement setups, such as with penile probes, must be used to characterize weapon systems, but they cannot make valid statements about the real load on dynamically behaving soldiers. However, this real load on the soldier is essential in order to be able to adequately assess the potential resulting medical effects.
As part of this challenging measurement task, a prototype of a self-sufficient, high-resolution measurement system is presented, which can be used by an operator in dynamic situations without interference. The complete measuring chain was realized as a self-sufficient unit. The system is based on a 20-liter backpack system, which contains the power supply, the measuring amplifier and the measuring card (see Fig. 1, left). The measuring computer is attached to the front of the backpack to allow quick access. The measuring system is capable of recording four channels with a sampling rate of up to 2 MHz. Piezoelectric integrated charge pressure sensors are used as a high-resolution pressure sensor (type: PCB138B32). The pressure sensor is placed on a XX- carrier plates with the dimensions XY × YY. The pressure sensors are attached at the typical positions for Blast-Gauges measurements, like on the left shoulder, on the upper chest and on the back of the head. At the same time, commercial blast gauges are placed at the positions of the pressure sensors to qualify the blast gauges (type: B3 Blast Gauges Gen 6). The measuring system is referred to as a “Sensor Carrier Operator (StEk)”.
As part of the functional testing of the measurement system, tests are carried out with hand weapons. For this purpose, a soldier is equipped with the StEk and blast gauges. The handguns used are the pistole P8 (caliber 9 mm) and the long rifle G36 (caliber 5.56 mm). The firing position is standing freehand. In addition, the soldier carried out an examination of the carrying comfort of the StEk as part of the training. Furthermore, it was evaluated whether the measuring chain was adequately integrated into the measuring system. The quality of the pressure measurement was also examined, whereby a direct comparison was made with the blast gauges (see Fig. 1 right).
The measurement system presented here enables the combined (static and dynamic) scientific characterization of weapon systems, particularly with regard to overpressure loading
Reliable analysis of the elemental composition of graphene oxide flakes with energy dispersive spectroscopy (SEM/EDS) and x-ray photoelectron spectroscopy (XPS)
No full textSuspensions of graphene-related 2D materials (GR2M) are broadly used for further applications like printable electronics. The reliable quantification of the composition of graphene-related 2D materials as liquid suspensions is still a challenging task, which can hinder the commercialisation of the products. Specific parameters to be measured are defined, e.g. the oxygen-to-carbon (O/C) concentration ratio, the trace metal impurities, or the functional groups present [1], but reference protocols are still missing. One of the central methods for the quantification is X-ray photoelectron spectroscopy (XPS) as a rather expensive method. Therefore, the development of cheaper alternatives is highly desired. One attractive alternative of XPS is energy-dispersive spectroscopy (EDS) which is usually coupled with scanning electron microscopy (SEM). This combination is one of the most widely used methods in analytical laboratories. In this contribution the results of a systematic study on the capability of SEM/EDS to reliably quantify the O/C ratio in a well-defined and well-characterized graphene oxide material [2] are presented. The robustness of the SEM/EDS results obtained at various measurement conditions (various excitation energies) is tested by comparing the results to the established XPS analysis [3], which has been carried out on the same samples.
It is demonstrated that for samples prepared by drop-casting on a substrate, both surface-sensitive XPS analysis and bulk-characterising EDS result in very similar elemental composition of oxygen and carbon for thick spots. Further, the effect of untight deposited material enabling co-analysis of the (silicon) substrate, is evaluated for both methods, XPS and EDS. The last results clearly show the influence of the substrate on the analysis of the results and stressed out the importance of the sample preparation
Update from ISO/TC 61/SC14/WG4
No full textThis talk is an update from ISO/TC 61/SC14/WG4. It describes the production of microplastic test material for the use in an interlaboratory comparison. IWe report the first results of an ILC on microplastic detection methods organized under the pre-stantdardisation plattform of VAMAS (www.vamas.org/twa45/) as Project 2 “Development of standardized methodologies for characterisation of microplastics with microscopy and spectroscopy methods”, within the Technical Working Area TWA 45 “Micro and Nano Plastics in the Environment”. The ILC has gathered 84 participants all over the world representing all continents. Reference materials were developed by BAM to test the main methods for MPs detection as addressed in ISO/TR 21960:2020: thermo-analytical methods (Py-GC/MS and TED-GC/MS) and vibrational methods (µ-IR and µ-Raman). As far as the mass fraction is concerned, accurate results with quite a good precision were achieved with the thermo-analytical methods. Number-based results are not adressed here
Kalte Kiste - Tieftemperatur Transport eine sichere Option für kritische Batterien?
No full textObwohl Batterien und im Besonderen Lithiumbatterien bei normaler Benutzung sicher sind, kann ein Fehlerfall zu einem katastrophalen Event führen. Dabei können giftige Gase frei werden und es kann bis zum Brand der gesamten Batterie kommen. Daher muss der Transport beschädigter Batterien unter sicheren Bedingungen erfolgen. Die Zuständigkeit für den sicheren Transport kritisch defekter Batterien in Deutschland hat die BAM inne. In diesem Zusammenhang erforscht die BAM an sicheren Transportbedingungen, welche im Rahmen dieser Präsentation vorgestellt werden. Dabei zeigen Lithiumbatterien unterhalb einer individuellen Temperatur keinerlei Reaktionen bei kritischer Beschädigung. Diese Temperatur wird als initiale Reaktionstemperatur (IRT) definiert. Ferner kann diese IRT mit einem einfachen elektrischen Test bestimmt werden. Ein Auftauen nach der kritischen Beschädigung kann dennoch zum thermischen Durchgehen (TR) führen. Dieser kann jedoch zusätzlich auch lokal begrenzt auftreten. Das Schockfrosten während des laufenden TR führt nicht immer dazu, dass der TR gestoppt wird
Close encounters on a micro scale: Dynamics and interactions of microplastic biofilms in aquatic ecosystems.
No full textMicroplastics circulate freely throughout aquatic ecosystems and, due to their interactive nature, accumulate complex polymeric matrices consisting of rich organic compounds and inorganic pollutants. Simultaneously, these hardy substrates offer nutrition and protection to diverse microbial communities and their theatre of activity, representing a new ecological niche. In our work, we investigate the interactions of microplastics in aquatic systems and characterise the effects of these interactions on associated microbial communities to better understand how these substrates might impact surrounding ecosystems. Demonstrating no specificity to polymer type, microplastic biofilms are shaped more by the strong influence of spatial and temporal factors. Microplastic sorption of polycyclic aromatic hydrocarbons (PAHs), in contrast, appear to be more strongly dictated by substrate type, with different polymers observed to sorb varying levels of different PAHs. These interactions between the different emerging contaminants were found in our study to have a significant effect on associated substrate biofilms. Elevated levels of specific 3- and 4-ring PAHs on polyethylene and polystyrene were found to coincide with a notable shift in community composition and structure, as well as a reduced diversity among biofilm communities. The findings in our study illustrate the importance of investigating the collective effect of pollutants in combination and their complex interactions in assessing their environmental impact. To fully understand how microplastics interact and alter surrounding ecosystems, the entire substrate must be considered, including all chemicals integrated into the polymeric matrix
Bio-sourced Flame Retardant System for Engineering Plastics
No full textMain message: Intumescent flame retardant degradation products react with the lignocellulose hydroxyl groups by esterification, causing enhanced effectiveness in char formation [1]. The aim of this work is to prepare polyamide 11 with lower flammability by modifying it with a plant-based flame retardant system. An innovation is the thermal modification of plant raw materials to establish bio-sourced flame-retardant systems dedicated to engineering materials.
Introduction: Using plant fillers to modify engineering materials raises concerns due to too low thermal stability and problems during processing. However, substances participating in char formation, such as cellulose and lignin, have higher decomposition temperatures than the processing temperature of most engineering plastics. Appropriate preparation of lignocellulosic materials through modification by thermal methods will enable their partial decomposition in controlled conditions and eliminate components with low thermal stability.
Results and Discussion: For PA11, the heat release (HRR) curve is characterized by two peaks (Fig.1), with a maximum value at the end of burning. The flame retardant systems caused the curves to flatten, which was especially visible for samples with the highest sunflower husk share. The maximum values of heat release rate (pHRR) for samples with FRs varied from 991 to 626 kW/m2 and were much lower compared to PA11 (2152 kW/m2) and MPP (1234 kW/m2). All samples with FRs ignited much earlier than the reference materials, especially compared to unmodified polymer (Tab.1). The maximum average rate of heat emission (MARHE), used to forecast flame spread, decreased compared to PA11 (maximum by 30%) and slightly to MPP. Decreases were also noted in the case of total heat emission (THE), corresponding to the total heat released at the end of flame combustion. The values range from 112 to 127, and depending on the series, an increase (SH) or decrease (SHT) with the growth of the amount of bio-based components was observed. The reduction in THE follows from incomplete combustion as an effect of char forming or reduced combustion efficiency [2]. Char formation was proved by an increase in the yield of residue , while a slight decrease in the effective heat of combustion (EHC) suggests activity in the gas phase. Smoke emission was assessed by specific extinction area (SEA). The SEA reduction was noted only for the MPP sample, and introducing sunflower husks increased the smoke released
Synergistic effect of commercial and natural flame retardants in polylactide biocomposites
No full textMain message: We propose a combination of natural biomass from algae species Desmodesmus sp.along with commercially available flame retardant Melapur200 (melamine polyphosphate) in different mass ratios. We have successfully demonstrated that the use of both of them in PLA matrix biocomposites shows a synergistic flame retardant effect. Introduction: Poly(lactic acid) (PLA), a biodegradable polymer produced from renewable resources such as corn starch and sugarcane, is increasingly being used as a substitute for traditional petrochemical-based polymers in various commercial applications. However, its flammability characteristics need improvement to enable its use as a technical polymer. Based on previous successful experiments on PLA biocomposites with phosphor-enriched algae as filler [1], it was even mandatory to continue with enhancement of PLA flame retardancy. Therefore, tests for PLA biocomposites with P-algae containing melamine polyphosphate at different mass ratios were performed. Pyrolysis, reaction to small fire and fire behavior tests were carried out. Results and Discussion: Thermal stability analyses showed that all composites decompose earlier at lower temperature than pure PLA to a small extent. The evolved gases analysis revealed the release of ammonia and phosphates for the composites tested. PCFC analysis showed the greatest decrease in pHRR for the sample containing Melapur200/Algae (Figure 1A). Similarly, in the fire behaviour analysis, the best result was obtained for the sample containing a mixture of Melapur200 and Algae (Figure 1B). Satisfying results were obtained in the tests of reaction to small flame, where all the samples passed the classification from V-2 to V-0 (in the UL 94 test) and the oxygen index for the best sample was 27.4 +- 0.2%. When only Melapur200 or algae are added separately, a slight flame retardant effect is visible, however if both materials are added in suitable mixtures to the polymer, a synergistic effect is observable. In some cases, it can even be observed that the synergistic effect has surpassed expectations from the superposition. In conclusion, the combination of Melapur200 together with microalgae gives satisfying flame retardant effects for PLA biocomposites. Acknowledgement: The authors thank Dr. Georgios Mourgas (Tecnaro GmbH), and Dr. Michael Schweizer (Tecnaro GmbH) for their contributions to conceptualizing the project, raising the grant, and supporting this work. Thanks to Dr. Robert Gleuwitz (formerly of the BAM), Dr. Claudia Thomsen (iSeaMC GmbH) and Prof. Dr. Laurenz Thomsen (formerly of Jacobs University Bremen, now University of Gothenburg), Thanks to the financial support of the Bundesministerium für Bildung und Forschung – BMBF: KMU-innovativ: Biooekonomie 031B1289
Collapse of the Carola Bridge in Dresden Part 1: From theambitious design to the tragic partial collapse
No full textAbstraktDer 11. September 2024 wird nicht nur der Brückenbaucommunity in Deutschland in Erinnerung bleiben. Der Teileinsturz einer Spannbetonbrücke ohne Vorankündigung schlug berechtigterweise gesamtgesellschaftlich hohe Wellen. Betroffen war die Dresdner Carolabrücke – ein ästhetisches und ausgesprochen schlankes Bauwerk, welches in der Fachwelt zurecht als eine Ikone der Ingenieurbaukunst ihrer Zeit angesehen wird. Die Konstruktion sowie der Bau wären auch unter den heutigen Möglichkeiten eine Herausforderung. Der vorliegende Teil 1 des Beitrags fasst die Entstehungsgeschichte, die Konstruktion selbst und den Bau der Brücke zusammen. Es werden die Maßnahmen zur Instandhaltung und Sanierung der Brücke vorgestellt. In einem Teil 2 wird der Versuch der Rekonstruktion des Einsturzvorgangs unternommen und die Suche nach der Einsturzursache beschrieben. Zudem wird auf das aktuelle Monitoring eingegangen und ein Ausblick auf das mögliche weitere Vorgehen gegeben