Filtern
Dokumenttyp
- Zeitschriftenartikel (16)
- Vortrag (2)
- Posterpräsentation (2)
- Beitrag zu einem Tagungsband (1)
- Sonstiges (1)
Schlagworte
- Microplastics (4)
- Polyurethane (3)
- TED-GC-MS (3)
- Antibacterial (2)
- FTIR (2)
- Friction (2)
- Intermodulation AFM (2)
- Micropatterning (2)
- Polydopamine (2)
- Rosin (2)
- TPU (2)
- AFM (1)
- AFM force spectroscopy (1)
- Analysis and identification (1)
- Artificial weathering (1)
- Bacterial lipopolysaccharides (1)
- Bewitterung (1)
- Biological techniques (1)
- Biomimicry (1)
- Cellulose acetate (1)
- Cellulose nanofibrils (1)
- Composite (1)
- Composites (1)
- Crosslinking (1)
- DPP (1)
- Degradation (1)
- Digitales Zertifikat (1)
- Digitalisierung (1)
- Direct laser interference patterning (1)
- Electron microscopy (1)
- Electron tomography (1)
- Electrospinning (1)
- Environmental Science (1)
- FTIR imaging (1)
- Femtosecond laser (1)
- Feuchte (1)
- GPC (1)
- Hierarchical structures (1)
- Humidity (1)
- IR (1)
- Infrared nano AFM (1)
- Interphase (1)
- Laser-induced periodic surface structures (LIPSS) (1)
- Lignin (1)
- Microplastic (1)
- Modulus (1)
- Moisture (1)
- Multiphoton lithography (1)
- NanoIR (1)
- Nanocomposites (1)
- Nässe (1)
- Oxidation (1)
- PUR (1)
- Photooxidation (1)
- Polycarbonate (1)
- Polystyrene microparticles (1)
- Polyurethan (1)
- Principle component analysis (1)
- Propolis (1)
- Pseudomonas aeruginosa (1)
- Quality (1)
- Qualitätsinfrastruktur (1)
- Qualitätssicherung (1)
- RAMAN (1)
- Raman (1)
- Raman imaging (1)
- SAXS (1)
- SEC (1)
- Smart Standard (1)
- Structure–property correlation (1)
- Surface functionalization (1)
- Swell-capture (1)
- Thermoanalytics (1)
- Thermoplastics (1)
- Titanium (1)
- Two-photon polymerisation (1)
- UV (1)
- UV radiation (1)
- Van der Waals forces (1)
- Vibrational Spectroscopy (1)
- Waste water treatment (1)
- digitale Transformation (1)
Organisationseinheit der BAM
- 6 Materialchemie (15)
- 6.6 Physik und chemische Analytik der Polymere (14)
- 6.1 Oberflächen- und Dünnschichtanalyse (4)
- 5 Werkstofftechnik (3)
- 6.2 Material- und Oberflächentechnologien (3)
- 1 Analytische Chemie; Referenzmaterialien (2)
- 1.2 Biophotonik (2)
- 5.1 Mikrostruktur Design und Degradation (2)
- 6.3 Strukturanalytik (2)
- 6.7 Materialsynthese und Design (2)
Paper des Monats
- ja (1)
Eingeladener Vortrag
- nein (2)
Branched Polyurethanes Based on Synthetic Polyhydroxybutyrate with Tunable Structure and Properties
(2018)
Branched, aliphatic polyurethanes (PURs) were synthesized and compared to linear analogues. The influence of polycaprolactonetriol and synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) in soft segments on structure, thermal and sorptive properties of PURs was determined.
Using FTIR and Raman spectroscopies it was found that increasing the R,S-PHB amount in the structure of branched PURs reduced a tendency of urethane groups to hydrogen bonding. Melting enthalpies (on DSC thermograms) of both soft and hard segments of linear PURs were higher than branched PURs, suggesting that linear PURs were more crystalline. Oil sorption by samples of linear and branched PURs, containing only polycaprolactone chains in soft segments, was higher than in the case of samples with R,S-PHB in their structure. Branched PUR without R,S-PHB absorbed the highest amount of oil. Introducing R,S-PHB into the PUR structure increased water sorption.
Thus, by operating the number of branching and the amount of poly([R,S]-3-hydroxybutyrate) in soft segments thermal and sorptive properties of aliphatic PURs could be controlled.
The effects of weathering exposure on unfilled and filled thermoplastic polyurethanes (TPU) materials are described as performed under different humidity conditions. For this purpose, a weathering device was used with UV-A 340 nm lamps at a constant temperature of 40 °C. The effects of environmental (UV and humidity condition) degradation on the frictional properties of TPU materials are presented along with surface analyses to characterize the chemistry of the degradative process. Photooxidative degradation of unfilled polymer leads to deterioration of physical and mechanical properties, which affects its tribological behavior significantly. Due to crosslinking, the stiffness of the material increases, reducing drastically the friction coefficient of unfilled TPUs. The frictional behavior of glass fiber reinforced TPU is less affected by radiation.
The antibacterial features of natural pine/spruce rosin are well established, yet the functionality in various thermoplastics has not been surveyed. This work focuses on the processing of industrial grade purified rosin mixed with polyethylene (PE), polypropylene (PP), polylactic acid (PLA), polyamide (PA) and corn starch based biopolymer (CS). Homopolymer masterbatches were extrusion-compounded and melt-spun to form fibres for a wide range of products, such as filters, reinforcements, clothing and medical textiles. Due to the versatile chemical structure of rosin, it was observed compatible with all the selected polymers. In general, the rosin-blended systems were shear-thinning in a molten condition. The doped fibres spun of PE and PP indicated adequate melt-spinning capability and proper mechanical properties in terms of ultimate strength and Young's modulus. The antibacterial response was found dependent on the selected polymer. Especially PE with a 10 wt% rosin content showed significant antibacterial effects against Escherichia coli DH5α and Staphylococcus aureus ATCC 12598 when analysed in the Ringer's solution for 24 h.
The quantitative difference in the antibacterial response was measured for pine rosin and propolis against Staphylococcus aureus ATCC 12598. The activity was studied for fibrous networks that form entirely bio-based cellulose-acetate (CA) materials. The analysis considers the effects of bacterial input, additive dosage, solvent type, variation in preparation, as well as the effect of storage time. Based on the results, the electrospun network structure is dependent on the solvent and the concentration of rosin and propolis. Both rosin and propolis improved the cellulose acetate solution processability, yet they formed beads at high concentrations. Rosin and propolis created strong antibacterial properties when these material systems were immersed in the liquid for 24 h at room temperature. The response remained visible for a minimum of two months. The electrospun networks of water and DMAc solvent systems with 1 to 5 wt% rosin content were clearly more efficient (i.e., decrease of 4 to 6 logs in colony forming units per mL) than the propolis networks, even after two months. This efficiency is likely due to the high content of abietic acids present in the rosin, which is based on the Fourier transform infrared spectra. The results of the additional analysis and cell cultivation with dermal fibroblast cells indicated an impairing effect on skin tissue by the rosin at a 1 wt% concentration compared to the pure CA fibers.
Atomic force microscopy based Infrared spectroscopy (AFM-IR) is a quickly evolving technique that provides chemical analysis and compositional mapping with spatial resolution far below conventional optical diffraction limits. This is possible since the detection method is based on a very sharp AFM tip which starts to oscillate when the sample starts to thermally expand (the changed is caused by the absorption of IR wavelength) where the thermal expansion is related to the IR absorption. This presentation briefly described the application of that new technique from polymer characterization and utilization of AFM-IR in material research, up to life science applications.
Einfluss von Feuchte und Nässe auf die Witterungs-induzierte Alterung am Beispiel eines Polyurethans
(2017)
In diesem Beitrag soll der relative Einfluss des Wassers als Feuchte und Nässe unter den Beanspruchungsfaktoren untersucht werden. Die Unterscheidung von Luftfeuchte und Nässe bezüglich ihrer Wirkung ist dabei notwendig, weil die stehende Nässe zusätzliche Extraktionswirkung besitzt und auch die verfügbare Sauerstoffmenge beeinflusst.
Dazu wurde ein Polymer, das im Rahmen des BAM-internen Projektes PolyComp untersucht wird, künstlich bewittert. Hierzu wurde ein Fluoreszenzlampengerät mit UV-A 340 nm Leuchtstoffröhren verwendet, in dessen Probenraum durch zusätzliche Kammern die gleichzeitige Bewitterung unter drei unterschiedlichen Feuchte-Varianten realisiert wurde (bei konstanter Temperatur):
- UV und trocken
- UV und hohe Luftfeuchte
- UV und stehende Nässe
Das gleichzeitige Einwirken der einzelnen Einflussfaktoren kann dabei konkurrierende oder aufeinander folgende chemische Reaktionen und physikalische Prozesse und somit ein anderes Ergebnis bewirken, als wenn sie isoliert nacheinander auf eine Probe eingewirkt hätten.
Über die erwähnten Varianten hinaus kann auch noch der spezifische Einfluss der UV-Strahlung mit untersucht werden, weil die Proben im Bereich ihrer Befestigung verdeckt sind.
Die Methodik und erste Ergebnisse dieser Untersuchung werden präsentiert.
Avoiding aerial microfibre contamination of environmental samples is essential for reliable analyses when it comes to the detection of ubiquitous microplastics. Almost all laboratories have contamination problems which are largely unavoidable without investments in clean-air devices. Therefore, our study supplies an approach to assess background microfibre contamination of samples in the laboratory under particle-free air conditions. We tested aerial contamination of samples indoor, in a mobile laboratory, within a laboratory fume hood and on a clean bench with particles filtration during the examining process of a fish. The used clean bench reduced aerial microfibre contamination in our laboratory by 96.5%. This highlights the value of suitable clean-air devices for valid microplastic pollution data. Our results indicate, that pollution levels by microfibres have been overestimated and actual pollution levels may be many times lower. Accordingly, such clean-air devices are recommended for microplastic laboratory applications in future research work to significantly lower error rate
An investigation of microplastic (MP) occurrence in a municipal wastewater treatment plant (WWTP) effluent with tertiary treatment was carried out. Representative sample volumes of 1 m3 were taken by applying a fractionated filtration method (500, 100, and 50 µm mesh sizes). The detection of MP mass fractions by thermal extraction desorption–gas chromatography/mass spectrometry (TED-GC/MS) was achieved without the previously required additional sample pretreatment for the first time. Different types of quantification methods for the evaluation of TED-GC/MS data were tested, and their accuracy and feasibility have been proven for real samples. Polyethylene, polystyrene, and polypropylene were identified in effluent samples. The polymer mass content varied significantly between 5 and 50 mg m−3. A correlation between the MP load and the quantity of suspended matter in the WWTP effluents, particle size distribution, particle type, and operation day (i.e., weekday, season, and capacity) was not found. It can be concluded that a meaningful assessment of WWTPs requires a comprehensive sampling campaign with varying operation conditions.
Produktion und Handel in immer komplexeren Wertschöpfungsnetzwerken, die fortschreitende digitale und grüne Transformation sowie technologische Innovationen sind in hohem Maße auf die verlässliche Sicherung und den effizienten Nachweis der Qualität, Sicherheit und Nachhaltigkeit von Waren, Dienstleistungen und Prozessen angewiesen. Unverzichtbar dafür ist eine moderne und leistungsfähige Qualitätsinfrastruktur (QI). Der Artikel stellt die Initiative QI-Digital, ihre Ziele und Aktivitäten für die digitale Transformation der QI vor.
Outer membrane lipopolysaccharides (LPS) play a crucial role in determining attachment behavior and pathogenicity of bacteria. The aim of this study was to develop a simple procedure for anchoring bacterial lipopolysaccharides to polystyrene (PS) microparticles as a model system for in situ attachment studies. By using a swellcapture methodology, commercially available LPS of Pseudomonas aeruginosa (strain ATCC 27316 serotype 10.22) was anchored onto PS microparticles in a proof-of-concept study. A detailed chemical and morphological characterization has proven the success of LPS incorporation. It was shown that the coverage and structure of the LPS film was concentration dependent. The procedure can easily be adapted to LPS of other bacterial strains to generate a synthetic model toolkit for attachment studies.