5 Werkstofftechnik
Filtern
Dokumenttyp
- Posterpräsentation (114) (entfernen)
Sprache
- Englisch (98)
- Deutsch (15)
- Französisch (1)
Referierte Publikation
- nein (114) (entfernen)
Schlagworte
- Glass (8)
- Additive manufacturing (5)
- Creep (5)
- Degradation (5)
- Microstructure (5)
- Additive Manufacturing (4)
- Coarsening (4)
- Corrosion (4)
- Crack growth (4)
- FAIR (4)
- Transmission electron microscopy (4)
- 316L (3)
- Ab-initio (3)
- Alloy 2618A (3)
- Crystallization (3)
- EBSD (3)
- Fatigue (3)
- Hydrogen (3)
- NTE (3)
- Nanoparticles (3)
- Oxidation (3)
- Soda-lime silicate glass (3)
- Sol-gel (3)
- Solid-state (3)
- TDEP (3)
- VSSA (3)
- Vickers (3)
- Bildanalyse (2)
- Crack Propagation (2)
- Crystal orientation (2)
- DCB (2)
- Dark-field transmission electron microscopy (DFTEM) (2)
- Depth-profiling (2)
- Deuterium (2)
- Electron beam induced modification (2)
- Electron microscopy (2)
- Environmental stress cracking (ESC) (2)
- FIB (2)
- GD-OES (2)
- Gold nanoparticles (2)
- High temperature corrosion (2)
- Imaging techniques (2)
- Inconel 686 (2)
- Iron oxide nanoparticles (2)
- Kikuchi (2)
- LTCC (2)
- Lattice parameters (2)
- Lithium Ion Batteries (2)
- Low Cycle Fatigue (2)
- Machine Learning (2)
- Metadata schema (2)
- Mikroplastik (2)
- NFDI (2)
- Ontologie (2)
- Ontology (2)
- Oxidglas (2)
- Plattform MaterialDigital (2)
- Polymer (2)
- Ratio refinement (2)
- Reference data (2)
- Referenzdaten (2)
- Robotische Glasschmelzanlage (2)
- Sample preparation (2)
- Sandwich (2)
- Selective laser melting (2)
- Semantic Web Technologies (2)
- Sintering (2)
- Sulfidation (2)
- Syngle Crystal alloy (2)
- TED-GC-MS (2)
- Ti-6Al-4V (2)
- ToF-SIMS (2)
- Water content (2)
- Water speciation (2)
- 3D (1)
- 3D imaging (1)
- 5G (1)
- AFM (1)
- AISI 304L (1)
- AM (1)
- Abwasser (1)
- Additiv gefertigter Stahl (1)
- Additive Fertigung (1)
- Aggressive environement (1)
- Aggressive environment (1)
- Aging mechanisms (1)
- Al-Cu-Li alloys (1)
- Alkali ions (1)
- Aluminium (1)
- Analysis (1)
- Anhydrite (1)
- Anisotropy (1)
- Artefact (1)
- Atacama Desert (1)
- Atmospheric Plasma Spraying (1)
- Atomic packing factor (1)
- Atomization (1)
- Austenitic stainless steel (1)
- Austenitic steel (1)
- Automation (1)
- BCS (1)
- BTS (1)
- Belebtschlamm (1)
- Bilanzierung (1)
- Bio Ceramics (1)
- Bioactive glass (1)
- Biofilm (1)
- Bioresorbable (1)
- Boden (1)
- Borate glasses (1)
- Brittle / ductile fracture behavior (1)
- Brittle fracture (1)
- CALPHAD (1)
- CALPHAD databases analysis (1)
- CCS (1)
- CMSX4 (1)
- Calcium cobaltite (1)
- Carbon Fiber Reinforced Plastics (1)
- Carbon capture (1)
- Carbon dioxide (1)
- Ceramic (1)
- Chemically Complex Alloy (1)
- Chemometrie (1)
- Chromium oxide (1)
- Co-axial monitoring (1)
- Complex concentrated alloy (CCA) (1)
- Composite (1)
- Computed Tomography (1)
- Corrosion resistance (1)
- Crack (1)
- Crack evolution (1)
- Crack healing (1)
- Crack propagation analysis (1)
- Crystal plasticity (1)
- DED-L (1)
- Dark-field transmission electron microscopy (1)
- Data Fusion (1)
- Data Integration (1)
- Data Interoperability (1)
- Data fusion (1)
- Demonstrators (1)
- Density (1)
- Destabilization (1)
- Dielectric Spectroscopy (1)
- Diesel (1)
- Diffraction Enhanced Imaging (1)
- Diffusion coefficient (1)
- Digital material representation (1)
- Digitaler Zwilling (1)
- Digitalisierung (1)
- Digitalization (1)
- Diopside (1)
- Dislocations (1)
- Distributed fiber optic sensors (1)
- EDX (1)
- Electromicroscopy (1)
- Electron Backscatter Diffraction (1)
- Electronic Lab Notebook (1)
- Environmental stress cracking (1)
- FeCr- alloys (1)
- Film depositition (1)
- Focussed ion beam growth (1)
- Fracture Toughness (1)
- Fracture surface analysis (1)
- Fraktografie (1)
- Fresnoit (1)
- Full Notch Creep Test (1)
- Full Notch Creep Test (FNCT) (1)
- Full-Notch Creep Test (FNCT) (1)
- Fused Filament Fabrication (1)
- GFRP (1)
- Glas (1)
- GlasDigital (1)
- Glasfaserverstärkter Kunststoff (1)
- Glass ceramic (1)
- Glass composition (1)
- Glass fiber reinforced polymers (1)
- Glass matrix composite (1)
- Glass melt (1)
- Glass structure (1)
- Glass transformation temperature (1)
- Glass-ceramic (1)
- Gypsum (1)
- HDPE Sorption (1)
- HV-Insulation (1)
- Hardness (1)
- Heat Treatment (1)
- High Cycle Fatigue (1)
- High Temperature Testing (1)
- High Voltage Insulation (1)
- High entropy alloy (1)
- High temperature (1)
- High-density polyethylene (1)
- High-entropy alloys (1)
- High-temperature corrosion (1)
- Hot stage microscopy (1)
- Hydrogen permeability (1)
- IR (1)
- In situ (1)
- In situ tensile test (1)
- In-situ tomography (1)
- In718 (1)
- Infrarotspektroskopie (1)
- Internal friction (1)
- Kavitation (1)
- Knowledge Representation (1)
- Kontrastierung (1)
- LCF (1)
- LMD (1)
- LTCC multilayer (1)
- Laser Beam Melting (1)
- Laser Cladding (1)
- Laser Powder Bed Fusion (1)
- Laser ablation in liquid (1)
- Laser cladding (1)
- Lightweight materials (1)
- Lithium-ion batteries (1)
- Local landscape evolution (1)
- Long-term behavior (1)
- Low cycle fatigue (1)
- ML (1)
- Manganese oxide (1)
- Material characterization (1)
- Material oxidation (1)
- Mechanical Behavior (1)
- Metal powder characterization (1)
- Metal seal (1)
- Metformin (1)
- Metrology (1)
- Micro computed tomography (1)
- Micromanipulation (1)
- Microplastics (1)
- Microstructure Analysis (1)
- Microstructure analysis (1)
- Mikrostruktur (1)
- Model alloy (1)
- Modeling (1)
- NFDI-MatWerk (1)
- NMR (1)
- Nahinfrarotspektroskopie (1)
- Nano-landscape (1)
- Nano-powder characterization (1)
- Nanomaterial screening (1)
- Non-Destructive Testing (1)
- Optical criterion (1)
- Orientation (1)
- Orientation-dependent microstructure (1)
- Oxide Glasses (1)
- PE-HD (1)
- PMD Core Ontology (1)
- PMDco (1)
- Particle size (1)
- Peem (1)
- Photocatalysis (1)
- Polyethylene, PE-HD (1)
- Polymer-Ceramic-Composite (1)
- Porosity (1)
- Precipitation (1)
- ProMoAM (1)
- Process Monitoring (1)
- Property simulation (1)
- Prozessmonitoring (1)
- Präparation (1)
- Pulveraktivkohle (1)
- Reference Data (1)
- Reference Dataset (1)
- Reference material (1)
- Reference nanomaterials (1)
- Reliable characterization (1)
- Research Data Management (1)
- Residual stress (1)
- Risswachstum (1)
- Robot-assisted galss melting (1)
- Roboter (1)
- Rotorblätter (1)
- Röntgenbeugung (1)
- Röntgenrefraktion (1)
- S-phase (1)
- SEM (1)
- SIMS (1)
- SLM (1)
- Salt melt (1)
- Sandwichstruktur (1)
- Scale-bridging (1)
- Scanning electron microscopy (SEM) (1)
- Scarf joint repairs (1)
- Schadensanalyse (1)
- Semantic Data (1)
- Semantic Interoperability (1)
- Silver (1)
- Silver glass paste (1)
- Silver nanoparticle (1)
- Simulation (1)
- Size and size distribution (1)
- Slurry (1)
- Small angle x-ray scattering (1)
- Sodium zinc borate glass (1)
- Sodiumborosilicate glasses (1)
- Soil sample (1)
- Starch (1)
- Starch nanoparticle (1)
- Sulfiding (1)
- Superalloy (1)
- Surface (1)
- Surface Energy (1)
- Surface crystallization (1)
- Surface energy (1)
- Synchrotron (1)
- Synchrotron Tomography (1)
- Synchrotron tomography (1)
- Synthetic air (1)
- TEM (1)
- Tensile Properties (1)
- Thermal Spray (1)
- Thermoanalyse (1)
- Thermodynamic analysis (1)
- Thermoelectric generator design (1)
- Thermoelectric oxides (1)
- Thermogravimetrie (1)
- Thermomechanics (1)
- Time-offlight Diffraction (TOFD) (1)
- Titanium (1)
- Titanium oxide (1)
- Topografie (1)
- Transmission electron microscope (TEM) (1)
- Ultrasonic Testing (1)
- Ultrasound (1)
- VM12 SHC (1)
- Vickers indentation (1)
- Virtual experiments (1)
- Viscosity (1)
- Wind turbine blade shells (1)
- Wind turbine blades (1)
- X-Ray Diffraction (1)
- X-ray refraction (1)
- XRD (1)
- Young´s Modulus (1)
Organisationseinheit der BAM
- 5 Werkstofftechnik (114) (entfernen)
1. Introduction
A normally unwanted process that can arise when converging an electron beam onto, e.g. microparticles, has been called "damage induced by electric field" (DIEF) [1]. By DIEF, the convergent electron beam (CEB) imparts a high amount of energy to the microparticle locally and strongly interacts with its atoms. At a specific current density J, which can be controlled by the convergence angle α, the irradiated material begins to transform. The phenomenon of expelling nanomaterial from microparticles under the influence of a convergent electron beam (CB) in a transmission electron microscope (TEM) has been largely studied [2]. Several types of nanoparticles (NPs) have been observed for different metallic materials and metal oxides after specific CB protocols (P) in the TEM. Thus, DIEF can be used as a promising synthesis method controlled changes of micrometric material to create new nanometric material compositions and morphologies.
While these reactions have been observed in situ at the high acceleration voltages associated with TEM, it remains unclear whether the SEM can also be used to fabricate NPs via DIEF. In contrast to TEM there is no possibility to statically convert the electron beam to a range of α to reach the needed J as in TEM. Instead, the scanning parameters and the magnification can be manipulated so as to find an integrated J. Considering that the scanning electron microscope (SEM) is easier to use, more accessible and cheaper than a TEM, here we explore the possibility to transfer the concepts of DIEF known to operate in the TEM for in situ NP generation SEM.
2. Objectives
The main goal is to determine whether DIEF can be translated to the SEM perform to controlled in situ fabrication of nanoparticles from microparticles, using gold microparticles on amorphous SiO substrate as precursors. We determine what experimental parameters must be taken into account to create SEM-based CBPs for NP creation in the SEM with these materials.
3. Materials & methods
Gold microparticles with diameter of around 1 to 3 µm were deposited on electron transparent amorphous SiO/SiO2 substrate. Using a convergent electron beam protocol (CBP) in a scanning electron microscope (SEM) at an acceleration voltage of 30 kV, the gold microparticles were irradiated until a production of NPs takes place as shown in figure 1. The beam current varied between 16 and 23 nA.
4. Results
Depending on the CBP parameters, either only Au NPs or a mixture of Au and Si NPs are produced. The particle size ranges from a few nm up to 100 nm, and it depends on the distance of the NP to the initial position of the microparticle. Further beam parameters such as the dwell time, the effective irradiated volume and particle size determine whether NPs are produced or if the microparticles only are expelled from the substrate without reacting.
5. Conclusion
The SEM can be used as an instrument for synthesizing nanomaterials via DIEF. Different CBP protocols can be applied for obtaining either gold nanoparticles or silicon + gold nanoparticles
The phenomenon of expelling nanomaterial from microparticles of different materials, such as Au, WO3 or B2O3 under the influence of a convergent electron beam (CB) of a transmission electron microscope (TEM) was reviewed by Ignacio Gonzalez-Martinez [1]. Converging the e-beam in a TEM means that a high amount of energy enters the microparticle at a very local place and interact with the matter. Obviously, during the convergent beam protocol, no imaging with the electron beam is possible, but at the end, nanoparticles with different appearances lie down next to the microparticle while its size is reduced.
Hence, there is a blind spot in the observation, which we want to fill, as we want to help clarify the nature of the expelling phenomenon. One hypothesis that explains the phenomenon is the so-called damage (of the microparticle) induced by an electric field (DIEF). Within this theory, the material is ionized and expelled in form of ionic waves. Our aim is therefore to fabricate specimens with artificial microlandscapes, as schematically exemplified in figure 1a), using the focused ion beam (FIB) and micromanipulators, as experimental setups to follow the paths of the expelled material.
As a first step towards the fabrication of such specimen, we make experimental feasibility studies for each fabrication method, FIB structuring with Ga+ ion beam and micromanipulated microparticle deposition. Bridges (gray regions in Fig. 1) are created by milling a commercially available electron transparent membrane (silicon oxide or carbon) of a Cu-TEM grid. Platinum or carbon walls (blue features in Fig. 1) are built to stand on those bridges. Microparticles (yellow sphere in Fig. 1) of gold or other material are deposited in the center of the bridges.
Figure 2a) shows four square holes (black area) and between them the residual silicon oxide membrane bridges (dark grey). On top of the bridges, walls (light grey) are deposited. The width of the bridges is different, the walls overlap the holes as well as the distance between the walls is very small, so these and other parameters need to be optimized. Figure 2b) shows a square hole (black) with bridges (white) on the right side on top of a carbon membrane (grey). There are still some obstacles which needs to be eliminated. For instance, the deposition process of the walls is not reliable as visible at the wall on top where a hole arises instead of a wall.
These studies are still in progress and the results are further discussed in terms of the applicability for the DIEF experiment in the TEM.
Damage induced by electric field (DIEF) that happens in the transmission electron microscope (TEM) when converging the electron beam (e-beam) on microparticles (MPs) can be used to synthesis new nanomaterial and nanomaterial compositions. The research questions are to clarify the limits and possibilities of the method regarding materials that can be produced, systems to which it is applicable and working beam parameters. Synthesis of nano-objects from microparticles using DIEF in TEM could be shown for different materials. Additionally, DIEF using the e-beam in a scanning electron microscope (SEM) can also be used to synthesis nano-objects. A deeper material analysis of this nano-objects was done using TEM and shows that the material of the nanoparticles (NPs) can be gold or/and silicon. Furthermore, the size of the NPs depends on the distance to the center of DIEF whereby the larger NPs are closer to the center. The areas of gold NPs are promising candidates for plasmonic or photonic devices for energy storage or transport.
Gypsum (CaSO4∙2H2O) and anhydrite (CaSO4) are among the dominant evaporite minerals in the Atacama Desert [1]. They are distributed ubiquitously, and play a key role in local landscape evolution.
The formation mechanism of especially anhydrite has been a matter of scientific debate for more than a century [2]. To date, there exists no model that can reliably predict anhydrite formation at earth’s surface conditions. While thermodynamics favor its formation [3], it is hardly achieved on laboratory time scales at conditions fitting the Atacama Desert. Long induction times for nucleation have recently been modeled by Ossorio et al. [4]. However, anhydrite can be readily found in the Atacama Desert. Recently, the mineral was synthesized in flow-through reactors as a byproduct of K-jarosite dissolution at high water activity (aw=0.98) and room temperature [5], even-though the thermodynamic stability field begins only under a value of ~0.8. Additionally, recent studies investigated the nano-structure of various calcium-sulfates, which advocate for highly non-classical crystallization behavior [6]. The specific roles of particulates, ionic or organic reagents working as catalysts for the non-classical crystallization pathway remain to be determined.
Here, we present recent results from flow-through experiments as well as analyses of anhydrite samples from the Atacama Desert. Flow-through experiments were performed to systematically explore the domains of flow rate, composition, ionic-strengths and starting materials. Neither primary, nor secondary anhydrite was produced in any of these experiments. Analyses on Atacama samples reveal the existence of at least three distinct anhydrite facies, with differing mineralogy and micro- to nano-structures. The facies are (1) aeolian deposits with sub-µm grain sizes, (2) (sub-)surface nodules that formed from aeolian deposits and (3) selenites with secondary anhydrite rims. Possible mechanisms of their formation will be discussed.
Glass strength and fatigue is limited by surface cracks. As subcritical crack growth (SCCG) is governed by ambient humidity, stress corrosion at the crack tip is widely accepted to be the underlying mechanism. However, as water is known to have decisive effect on glass properties and can rapidly enter the crack tip near glass region, SCCG could be affected by such water related phenomena. We tried to mimic these effects studying water dissolution and speciation, mechanical properties, and SCCG in water-bearing glasses. For this purpose, glasses up to 8 wt% water have been prepared by means of high-pressure melting of glass powder - water mixtures.
As part of this effort, SCCG in dry and hydrous commercial micros¬cope slide glass (CW = 6 wt%) was studied in double cantilever beam (DCB) geometry and sub-Tg relaxation was measured by Dynamic Mechanical Analysis (DMA).
For SCCG in ambient air (24% r.h.), SCCG was promoted by the presence of 6wt% bulk water with respect to the dry glass. On the other hand, stress intensity values, KI, required to cause slow crack growth (v < 10-6 ms-1) resemble literature findings for float glass of similar composition in liquid water, which might represent the maximum possible promoting effect of ambient water on SCCG.
For SCCG in vacuum (10-3 mbar), dissolved bulk water causes even more pronounced effects. Most strikingly, it strongly decreases the slope of the log v(KI)-curve, which is a measure of dissipated energy during fracture. A strong increase of sub-Tg relaxation with increasing water content was confirmed by DMA. As a consequence, slow crack growth occurs at KI values as measured in the dry glass whereas fast crack growth occurs at much larger KI than that of the dry glass. Kinks and shoulders shown by the inert log v(KI)-curve indicate that bulk water does not simply affect bulk mechanical properties.
GlasDigital
(2023)
Der aktuelle Stand des MateriaDigital1 Projektes GlasDigital wird vorgestellt. Hierbei wird allgemein die Problem- und Zielstellung präsentiert, als auch auf 2 separaten Postern die Ergebnisse. Diese beinhalten zum Einen die smarte Gestaltung der robotergestützten Glasschmelzanlage der BAM inkl. Analytik und zum Anderen die Digitalisierungsbestrebungen im Bereich Glas, d.h. ML-gestützte C-S-P-Simulation, Ontologie für den Werkstoff Glas, Digitaler Zwilling des Gießprozesses.
As part of a joint project involving the Fraunhofer Institute for Silicate Research (ISC), the Friedrich Schiller University of Jena, the Clausthal University of Technology and the Federal Institute for Materials Research and Testing (BAM), digital tools are to be created for the development of new types of glass materials. Current processes for the production of glasses with improved properties are usually very cost- and energy-intensive due to the low degree of automation and are subject to long development cycles. The use of robotic synthesis processes in combination with self-learning machines is intended to overcome these problems in the long term. The development of new types of glass can then not only be accelerated considerably, but also be achieved with much less effort.
In this talk, data generation via a robotic high-throughput glass melting system is presented, which should be the experimental basis for the ontology developed within the project GlasDigital.
Premature failure of glass under load is caused by sub-critical crack growth (SCCG) originate from microscopic flaws at the surface. While SCCG is related to the humidity of the ambient atmosphere, leading to stress corrosion phenomena at the crack tip, the detailed mechanism and the effect of different network formers are still not fully understood. For more clarity, various soda silicate glasses with a second network former were investigated by double cantilever beam technique: Na2O*Al2O3*SiO2 (NAS), Na2O*B2O3*SiO2 (NBS), Na2O*PbO*SiO2 (NPbS).
Three effects on the crack growth velocity, v, versus stress intensity, KI, curves were found out. The slope in region I, which is limited by corrosion, increases in the order NAS < NBS ≲ NPbS. The velocity range of region II reflecting the transition between corrosion effected and inert crack growth (region III), varies within one order of magnitude between the glasses. The KI region of inert crack growth strongly scatters between 0.4 and 0.9 MPam1/2. For comparison, crack growth at different humidity in commercial soda lime silicate glass (NCS) was measured.
Für die Erfassung der Verbreitung von Mikroplastik (MP) in der Umwelt ist die zeit- und kostenaufwendige Analysestrategie und der damit verbundene geringe Probendurchsatz eine limitierende Größe. Eine große Zahl verschiedener Studien dokumentriet das Auftreten von MP über den gesamten Globus. Meist sind die Studien aufgrund des großen analytischen Aufwands auf exemplarische, stichpunktartige Untersuchungen kleiner Umweltaliquoten und zahlenmäßig kleiner Probenumfänge begrenzt. Um die Verbreitung, die Eintragspfade und den Verbleib von MP in der Umwelt besser zu verstehen und effektive Vermeidungsstrategien abzuleiten, ist es jedoch notwendig, analytisch mehr Proben erfassen zu können.
Bildgebende mikro-spektroskopische Methoden wie das Raman- und FTIR-Imaging ermöglichen eine zeitaufwendige, umfassende Charakterisierung kleiner Umweltaliquoten. Neben der Partikelanzahl sind zusätzlich Informationen zu Partikelgröße, Größenverteilung und Oberflächenmorphologie zugänglich. Chemische und thermische Extraktionsverfahren sind bereits deutlich schneller und können diese Informationen durch eine Massenbilanz vervollständigen. Die analysierbare Probenmenge ist jedoch auf Milligramm Mengen beschränkt.
Wir schlagen daher vor, die Analyse von Proben auf MP durch ein vorangestelltes Screening mit der Nahinfrarot-Spektroskopie (NIRS) zur komplementieren. In diesem wird bereits eine erste Einschätzung über die Präsenz von MP in einer Probe gefällt und dadurch die wertvolle Messzeit anderer Methoden effizienter genutzt.
NIR zur Analyse von Polymeren wird seit langem eingesetzt, jedoch bisher lediglich im Rahmen einer Studie zur Mikroplastikuntersuchung mittels Hyperspektraler Bildgebung beschrieben. Der NIR Spektralbereich findet sich zwischen dem sichtbaren Licht und dem mittleren Infrarot (MIR). MIR Spektren sind durch klar definierte Banden charakterisiert, welche mehrheitlich von den Grundschwingungen der Moleküle stammen. Die höheren Energien im nahen Infrarot regen hingegen Kombinations- und Oberschwingungen der Streck und Biegeschwingungen an. Die resultierenden Absorptionsbanden sind oft breit und relativ unspezifisch. Erst mit Hilfe einer computergestützten Datenauswertung lassen sich aus diesen Spektren nützliche Informationen gewinnen. Dies erklärt die steigende Popularität der NIR-Spektroskopie in der jüngeren Vergangenheit mit einem Schwerpunkt als prozessanalytische Methode. NIR Spektrometer für das industrielle Prozessmonitoring zeichnen sich durch eine kompakte und robuste Konstruktionsweise aus. Die verfügbaren faseroptischen Reflexionssonden eignen sich gut um pulverförmige Proben zu untersuchen. Der räumlich erfassbare Messbereich kann durch die Sondengeometrie variiert werden. Sind die untersuchten Partikel im Verhältnis zur abgetasteten Fläche klein, wird als spektrale Information die Summe der Absorption aller Partikel im Sichtfeld erfasst. Die Methode ist deshalb nicht für Detailuntersuchungen von MP geeignet, erlaubt es jedoch innerhalb weniger Minuten eine Einschätzung über das Vorkommen von Mikroplastik in einer Probe zu treffen.
Exemplarisch wurden für diese Untersuchungen vier der am weitesten verbreiteten Kunststoffe Polyethylen (PE), Polyethylenterephthalat (PET), Polypropylen (PP) und Polystyrol (PS) gewählt. Aus den additivfreien Polymeren wurden nach einer Kryo-vermahlung und anschließender Siebung (< 125 µm) Modellproben generiert. Die Polymere wurden dafür zu einem Massenanteil von 1 % mit einem Standardboden (LUFA2.3, gesiebt < 125 µm) vermischt. Die Gesamtmenge von 1 g je Probe wurde in Aluminiumbehältern präpariert und 8 Messungen an unterschiedlichen, zufällig gewählten Positionen vorgenommen. Die erhaltenen Spektren wurden zur Kalibrierung chemometrischer Modelle genutzt.
In einem hierarchischen Ansatz wurde anhand der NIR-Spektren eine Klassifizierung vorgenommen:
1. Bestimmung ob eine Probe MP enthält (Ja/Nein).
2. Identifikation der Polymere in der Probe.
Eine aussagekräftige Klassifizierung beruht auf einer Vorbehandlung der Spektren. Hierdurch werden die Unterschiede zwischen den einzelnen Polymerbanden hervorgehoben. Die Eignung der so erstellten Modelle wurde anhand eines Referenzmaterials und am Beispiel von Realproben erfolgreich getestet. Dabei zeigte sich, dass nicht nur in den erstellten Polymer-Bodenmischungen, sondern auch in den Rückständen von fermentiertem Bioabfall und in Filterrückständen einer Waschmaschine, MP richtig erkannt wurde. Weiterhin zeigten Tests mit Mikroplastik-freien Bodenproben unterschiedlicher Herkunft, dass keine falsch-positive Resultate erzeugt wurden. Alle vier untersuchten Polymere, d.h. PE, PET, PS und PP mit einem Massenanteil von 1 % in einer Bodenmatrix werden auch bei einer gemischten Polymerzusammensetzung mit der NIR-Spektroskopie erkannt.
Der kombinierte Einsatz von NIRS und Chemometrie ermöglicht die Entscheidung über ein potenzielles Vorkommen sowie die Zuordnung des Materials der enthaltenen Polymerpartikel für eine Massefraktion ≥ 1 % in einer (trockenen) Probenmenge von 1 g innerhalb von 10–15 min. Der zeitaufwendige Schritt der Methode liegt hier in der Erstellung geeigneter chemometrischer Modelle sowie deren Validierung. Wesentliche Voraussetzung ist dabei, dass bei der Kalibrierung die Varianz der zu erwartenden Partikel und der Matrix realistisch abgebildet wird.