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Mechanochemical pathways to sustainability: from molecular insights to applications
No full textMechanochemical Innovations for Sustainable Synthesis of Framework Materials and Industrial ScaleUp
Mechanochemistry has emerged as a powerful approach for sustainable materials synthesis and processing, with significant potential to meet the UN Sustainable Development Goals. This presentation will highlight our recent advancements in understanding, monitoring, and scaling-up mechanochemical synthesis of framework materials, focusing on the balance between fundamental understanding of reaction mechanisms and its practical applications in energy storage and energy transfer materials.
A central focus of our work has been the development and application of time-resolved in situ monitoring techniques for mechanochemical processes. Our research on real-time synchrotron X-ray diffraction has enabled unprecedented insights into reaction pathways and kinetics. Recently, we have successfully applied energy-dispersive X-ray diffraction for time-resolved in situ monitoring of reactive extrusion, marking a significant step towards ‘lighting up’ industrial-scale mechanochemistry.
Bridging fundamental understanding with practical applications, we have explored the mechanochemical synthesis of functional materials for energy storage and transfer, making process in the mechanochemical synthesis of highly proton-conductive metal phosphonates, demonstrating the potential of mechanochemistry to manufacture advanced materials for energy applications
Advancing sustainable synthesis through in situ monitoring and industrial scale-up of mechanochemical processes
No full textMechanochemistry has emerged as a powerful approach for sustainable materials synthesis and processing, with significant potential to meet the UN Sustainable Development Goals. This presentation will highlight our recent advancements in understanding, monitoring, and scaling-up mechanochemical transformations, focusing on the balance between fundamental understanding of reaction mechanisms and its practical applications in energy storage and energy transfer materials.
Our research has made significant strides in elucidating the fundamental mechanisms of mechanochemical reactions. We have investigated delayed polymorphism under mechanochemical conditions, revealing new insights into the interplay between mechanical impact, thermal effects, and structural transformations in molecular crystals. By employing variable temperature ball milling, we have demonstrated unprecedented control over polymorphic forms in organic cocrystals, opening new avenues for tailoring material properties.
A central focus of our work has been the development and application of time-resolved in situ monitoring techniques for mechanochemical processes. Our research on real-time synchrotron X-ray diffraction has enabled unprecedented insights into reaction pathways and kinetics. Recently, we have successfully applied energy-dispersive X-ray diffraction for time-resolved in situ monitoring of reactive extrusion, marking a significant step towards ‘lighting up’ industrial-scale mechanochemistry.
Bridging fundamental understanding with practical applications, we have explored the mechanochemical synthesis of functional materials for energy storage and transfer, making process in the mechanochemical synthesis of highly proton-conductive metal phosphonates, demonstrating the potential of mechanochemistry to manufacture advanced materials for energy applications. Addressing the challenges of industrial scale-up, we have investigated the role of solvent polarity in mechanochemical reactions, providing valuable guidance for optimizing organic syntheses such as the Knoevenagel condensation. This work contributes to our broader efforts to develop more efficient and sustainable chemical manufacturing processes.
Looking to the future, we will discuss emerging directions in mechanochemistry, including the development of continuous flow processes and the integration of machine learning approaches for reaction prediction and optimization. As we anticipate the next decade of research, we envision mechanochemistry playing an increasingly crucial role in sustainable chemical manufacturing and materials processing, with far-reaching implications for addressing global energy and environmental challenges
Cyclic Deformation Behavior of Laser Powder Bed Fused Stainless Steel 316L Role of the Manufacturing Induced Cell Structure
No full textThe cyclic deformation behavior of an austenitic 316L stainless steel produced by laser powder bed fusion in two heat treated conditions and featuring a low defect population is presented. Strain controlled push/pull tests were performed between room temperature and 600 °C. The PBF‑LB/M/316L exhibits an initial cyclic hardening, followed by a cyclic softening. The grade of softening decreases (i) with increasing test temperature and (ii) after a partial dissolution of its dislocation substructure through heat treatment. The deformation behavior and its dependency on test temperature and heat-treated/microstructural condition are attributed to the slip character and related changes. With either a partially dissolved dislocation substructure or increasing test temperature the material exhibits typical wavy slip characteristics. In the opposite case, the deformation mechanism seems to be rather planar dislocation slip as the formation of slip planes spanning through entire grains was observed, seemingly acting as pathways of easy dislocation movement
Referenzanalytik und Herstellung geeigneter Referenzmaterialien für die quantitative Elementanalyse von Batterierohstoffen
No full textDas vom BMFTR geförderte Vorhaben X@Line hat das Ziel, eine at-line-fähige Elementanalytik von Schwarzmassen mittels eines neuartigen Röntgenfluoreszenzverfahrens zu etablieren. Im Rahmen des Teilvorhabens "Referenzanalytik und Herstellung geeigneter Referenzmaterialien für die quantitative Elementanalyse von Batterierohstoffen" ist die BAM für die Auswahl und Herstellung geeigneter Referenzmaterialien zuständig und damit auch für die Referenzanalytik unter Verwendung von Methoden wie die optische Emissionsspektroskopie mit induktiv gekoppeltem Plasma (ICP-OES). Erste Untersuchungen der Schwarzmassen des Projektpartners Redux zeigen die Notwendigkeit, die verschiedenen Klassen an Schwarzmassen gesondert zu behandeln. Die Klassen unterscheiden sich je nach im Recycling eingesetztem Batterie-Typ. Die Batterie-Typen basieren auf ihren jeweiligen Kathodenmaterialien. Die Referenzmaterialien müssen demnach den Klassen entsprechend hergestellt werden. Des Weiteren müssen die Klassen auch bei der Entwicklung von Kalibriermodellen für die Röntgenfluoreszenzanalyse (RFA) berücksichtigt werden. Diese Notwendigkeiten ergeben sich aus der Matrixabhängigkeit der Röntgenfluoreszenzspektroskopie. Erste Klassifizierungsversuche wurden mit der Partial Least Squares Discriminant Analysis (PLS-DA) vorgenommen. Die PLS-DA kann die einzelnen Klassen anhand der semiquantitativen Ergebnisse der RFA clustern und für die entsprechenden Proben die jeweilige Klasse vorhersagen
Aus Schaden wird man klug - Der Teileinsturz der Carolabrücke liefert neue Prüf-und Schädigungsansätze für vergütete Spannstähle
No full textSpannstahlbrücken die in der Vergangenheit mir vergüteten Spannstählen errichtet worden sind können unter ungünstigen Gegebenheiten bei deren Erstellung signifikante Probleme hinsichtlich der Tragfähigkeit bekommen. Im Speziellen kann die wasserstoffinduzierte Spannungsrisskorrosion hier bei der Errichtung der Brückenbauwerke Anrisse an den Spanndrähten erzeugt haben die Jahre später zum Versagen der Brücke führen können. Die Präsentation im Speziellen behandelt den Teileinsturz der Carolabrücke in Dresden
Dataset for publication: Characterization of temperature influence on the structural built-up of 3D concrete
No full textImplementation, data, and results for the generation of the study "Characterization of temperature influence on the structural built-up of 3D concrete".
In this study, the influence of temperature on structural build-up is investigated. A significant temperature influence is demonstrated for three experimental setups (small amplitude oscillatory shear, constant shear rate, and small amplitude oscillatory extensional tests) using different materials.
A common modeling framework capturing the time- and temperature evolution is derived based on the maturity approach. Two alternative formulations for the time evolution were proposed. Both models were calibrated using a probabilistic approach, allowing for uncertainty quantification. The calibrated models successfully predict the structural build-up under different ambient temperature conditions
Assessment of Pd Nanoparticles as Chemical Modifiers and Preconcentration Agents for Cd Determination in River Water by HR-CS GFAAS
No full textCadmium is a heavy metal that can be hazardous to environmental and human health, even in trace levels.[1] In this way, the extraction and/or preconcentration of this element from environmental samples, such as river water, is important to obtain information about the composition and monitoring of potential contamination.[2] High-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) is widely used for Cd determination. However, the determination of this element at trace-level can be challenging, especially in complex matrices. Thus, nanoparticles (NPs) can be used as an alternative for the extraction and preconcentration of Cd in environmental samples, minimizing the potential interferences and improving the method´s limit of detection (LOD). Considering that Pd is also widely used as a “universal” chemical modifier, this project aims todevelop PdNPs capped with 3-mercaptopropionic acid (MPA) to assess its potential as a chemical modifier and preconcentration agent for Cd determination by HR-CS GF AAS in river water. In this way, the synthesis of PdNPs was performed in an aqueous medium by using ascorbic acid as a reducing agent. The characterization of PdNPs was performed by checking the size via dynamic light scattering (DLS), transmission electron microscopy (TEM), and inductively coupled plasma mass spectrometer in single particle mode (spICP-MS), where the median size was 56 ± 14 nm. The temperature program of HR-CS GFAAS was optimized for river water under three conditions: using Pd(NO3)2/Mg2+ (0.01%/0.5% m/v) as a chemical modifier (condition A), using Pd NPs as a chemical modifier (condition B), and without chemical modifiers (condition C). The pyrolysis and atomization temperatures for condition A were 900 and 1900 ºC, for condition B were 700 ºC and 1900 ºC, and for condition C were 500 and 1900ºC, respectively. Besides the temperature of pyrolysis for the universal chemical modifier being higher than that of PdNPs, using the PdNPs, the absorbance is significantly greater, according to the t-test for pairs, at a 95% confidence level. In addition, the evaluation of the preconcentration property of the PdNP was performed by adding 1 µg L-1 of Cd2+ in buffer pH 4 in two systems: one with and the other without PdNPs. After 1 h of stirring, both
systems were centrifuged at 3600 rpm for 10 min, and the absorbance in HR-CS GFAAS for Cd in both supernatants was evaluated. According to ANOVA from the t-test, at a 95% confidence level, there was a significant difference in the absorbance, indicating that Cd is interacting with the PdNPs. A multifactorial planning 2k, where k is the number of parameters of the extraction, which was time of extraction (10; 35; 60 min), Volume of Pd NPs (100; 300; 500 µL), pH (3; 5; 7), was used to evaluate the parameters with significant influence in the preconcentration of Cd2+. According to ANOVA, with 95% confidence, there is no lack of fit, and the parameters volume of PdNP and pH significantly influenced the response. In this way, the Doehlert methodology surface will be applied to both significant parameters. The goal is to achieve optimal conditions that increase the extraction efficiency of Cd2+ from environmental samples. The results indicate that the developed material is promising to use as a chemical modifier and for the preconcentration of Cd2+ in environmental samples
Flame retardant polylimonene carbonate: Material innovation as a game changer
No full textThis research seeks to understand and identify the most promising approaches to enhance the flame resistance of poly(limonene carbonate) (PLimC). Furthermore, the goal is to develop a PLimC-based material that incorporates halogen-free flame retardants (FRs) that are not only highly effective but also environmentally sustainable, contributing to the advancement of greener materials for safer use.
The plastic industry depends on fossil-based materials, causing environmental concerns. PLimC, a sustainable polymer derived from limonene and CO₂, offers a promising alternative. Its use in fire-safe applications underscores the need to optimize its performance. This study evaluates halogen-free FRs to identify and understand the most promising approaches to enhance PLimC’s flame resistance, aiming to improve fire safety and support eco-friendly material development.
This study has as its main task to conduct experimental evaluations to analyze the thermal properties, flammability, and fire behavior of each system. Pyrolysis, together with the evolved gases of the samples, were analyzed by thermogravimetric analysis coupled with a FTIR spectrometer. The energy content was determined by using a bomb calorimeter. The flammability of the samples was assessed by the reaction to small flame tests such as the UL 94 burning chamber and limiting oxygen index (LOI). The burning behavior in forced flamed conditions was evaluated using the cone calorimeter.
Thermal properties were first evaluated to gain a deeper understanding of the pure PLimC thermal stability and fire behavior. This analysis builds on PLimC's structural similarity to polycarbonate (PC), due to its carbonate group, and to polyolefins (PO), due to its aliphatic limonene-derived segment, providing insights into optimizing PLimC for sustainable, fire-safe applications.
The initial results, which defined our starting point, showed that the LOI of PLimC was 17.2%, very close to that of PO such as polyethylene (PE) and polypropylene (PP) (~18%). In contrast, PC has a higher LOI of ~24%. Additionally, PLimC did not produce any char (0 wt.-%), similar to PO, whereas PC forms char due to its phenolic structures. The effective heat of combustion of PLimC, measured using bomb calorimetry, was determined to be 31.1 MJ/kg. This value is comparable to that of PC (~30 MJ/kg) but significantly lower than PO (~44 MJ/kg). These findings, which demonstrated similarities to both PO and PC, prompted the evaluation of various commercially available FRs at standard market concentrations.
Four halogen-free FR systems were chosen for evaluation: 1. mixture of APP (20 wt.-%) + pentaerythritol (10 wt.-%) as an intumescent system [PLimC / APP / Penta], 2. mixture of the phosphorus compound PX200® (16 wt.-%) + PTFE (0.4 wt.-%) as antidripping [PLimC / PhosC / PTFE], 3. aluminum trihydroxide ATH (50 wt.-%) [PLimC / ATH], and the potassium sulfonate salt Bayowet® (0.4 wt.-%) [PLimC / SulfS]. The concentrations were decided according to the standards used in the industry.
Cone calorimeter results show that PLimC has the usual behavior of a non-charring specimen (fast burning and high peak of heat release). ATH proved to be the most effective flame retardant, achieving the biggest reductions in the effective heat of combustion (EHC) and total heat evolved (THE). Additionally, ATH achieved the highest increase in the LOI (17.1% to 26.0%). With these results, we understood that the FRs commonly used with polyolefins (at concentrations standard in the industry) exhibit similar behavior in terms of flammability and flame retardancy when applied to PLimC.
Additionally, we aim to investigate bio-based flame retardants to further improve the sustainability of the material. Given that phytic acid salts and lignin have demonstrated effective flame-retardant performance in polyolefins, we consider these compounds promising candidates for application in our system
Application of Elastic Reverse Time Migration to Ultrasonic Echo Data from Concrete Structures
No full textTo enhance ultrasonic imaging of concrete structures, we adapted the geophysical migration method, Reverse Time Migration (RTM), for non-destructive testing (NDT) in civil engineering. First, two 2D elastic RTM algorithms, each considering different wave types, were implemented and evaluated with synthetic ultrasonic data. The algorithm that best resolved numerical concrete structures was subsequently applied to real ultrasonic data from a concrete specimen. Compared with conventional synthetic aperture focusing technique (SAFT) imaging, elastic RTM reproduced a greater number of structural features in both the numerical model and the concrete specimen. In particular, elastic RTM reconstructed vertical interfaces as well as hidden lower edges of modeled cavities and tendon ducts. Notably, imaging the full cross-sections of tendon ducts, which enables direct diameter estimation, represents a novel achievement for ultrasonic NDT
Anwendungspotenziale von verzinktem Betonstahl in klinkerreduzierten Bindemittelsystemen unter Berücksichtigung spezifischer Korrosionsphasen
No full textKurzvorstellung zu einem DFG-Antrag. Themengebiet sind alterative Bindemittel für die Herstellung von Stahlbetonbauwerken in Kombination mit feuerverzinktem Betonstahl. Die Möglichkeit Bindemittel zu verwenden die keine Alkalitätsreserve vorhalten müssen lässt sich mit feuerverzinktem Betonstahl generieren. Hierbei können die pH-Werte um 8 mit einer Reduktion der Korrosionsgeschwindigkeit einhergehen, sofern man den direkten Vergleich mit hochalkalischen Betonen anstrebt