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  • 1
    Online-Ressource
    Online-Ressource
    Application of Mixing Rules for Adjusting the Flowability of Virgin and Post-Consumer Polypropylene as an Approach for Design from Recycling
    MDPI AG ; 2022
    In:  Polymers Vol. 14, No. 13 ( 2022-06-30), p. 2699-
    Details
    In: Polymers, MDPI AG, Vol. 14, No. 13 ( 2022-06-30), p. 2699-
    Kurzfassung: To enable the use of recyclates in thermoformed polypropylene products with acceptable optical appearance and good mechanical stability, a multilayer structure of virgin and recycled material can be used. When producing multilayer films with more than two layers, the used materials should have similar melt flow properties to prevent processing instabilities. In the case of a three-layer film, post-consumer recyclates are often hidden in the core layer. Due to the inconsistent melt flow properties of post-consumer recyclates, the adjustment of the melt flow properties of the core layer to those of the outer layers has to be realized by blending with virgin materials. In order to understand the effect of mixing with a virgin material with a certain pre-defined melt flow rate (MFR), material mixtures with different mixing partners from various sources were realized in this study. Hence, the pre-defined virgin material was mixed with (i) virgin materials, (ii) artificial recyclates out of a mixture of different virgin materials, and (iii) commercially available recyclates. These blends with mixing partner contents ranging from 0–100% in 10% increments were prepared by compounding and the MFR of each mixture was determined. For a mathematical description of the mixing behavior and furthermore for a proper MFR prediction of the material mix, existing mixing rules were tested on the three pre-defined sample groups. Therefore, this paper shows the applicability of different mixing rules for the prediction of the MFR of material blends. Furthermore, a new mixing rule was developed using symbolic regression based on genetic programming, which proved to be the most accurate predictive model.
    Materialart: Online-Ressource
    ISSN: 2073-4360
    URL: Article
    DOI: 10.3390/polym14132699
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2022
    ZDB Id: 2527146-5
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  • 2
    Online-Ressource
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    Resistance of Quench and Partitioned Steels Against Hydrogen Embrittlement
    Springer Science and Business Media LLC ; 2023
    In:  Journal of Materials Engineering and Performance Vol. 32, No. 11 ( 2023-06), p. 5186-5200
    Details
    In: Journal of Materials Engineering and Performance, Springer Science and Business Media LLC, Vol. 32, No. 11 ( 2023-06), p. 5186-5200
    Kurzfassung: Multiphase ultra-high strength steels (UHSS) containing retained austenite (RA) appear to be among the most interesting steels for the automotive industry. Developments in the last decades have allowed obtaining a very good combination of mechanical strength and ductility. Quenching and partitioning (Q & P) steels have been proposed as third-generation UHSS, reaching ultimate tensile strength up to 1300 MPa along with excellent fracture elongations of more than 15%. However, the use of Q & P steels is mainly limited by their susceptibility to hydrogen embrittlement (HE). The present work investigates the influence of the Q & P heat treatment parameters on the mechanical properties and on the HE resistivity of 20Mn-Si wire rod steel. The HE resistivity was measured using incremental step load testing with in situ electrochemical hydrogen charging according to ASTM F1624-12 standard. A comprehensive microstructure characterization was performed to examine volume fraction, nucleation sites and morphologies of RA. Although the mechanical properties were similar after Q & P heat treatment, an increase in the partitioning time revealed a significant increase in the HE threshold stress of more than 200 MPa.
    Materialart: Online-Ressource
    ISSN: 1059-9495 , 1544-1024
    URL: Article
    DOI: 10.1007/s11665-022-07438-4
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2023
    ZDB Id: 2048384-3
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  • 3
    Online-Ressource
    Online-Ressource
    Scanning electrochemical microscopy methods (SECM) and ion-selective microelectrodes for corrosion studies
    Walter de Gruyter GmbH ; 2022
    In:  Corrosion Reviews Vol. 40, No. 6 ( 2022-12-16), p. 515-542
    Details
    In: Corrosion Reviews, Walter de Gruyter GmbH, Vol. 40, No. 6 ( 2022-12-16), p. 515-542
    Kurzfassung: Over the last 30 years, scanning electrochemical microscopy (SECM) has become a fundamental technique in corrosion research. With its high spatial resolution and its ability to study local electrochemistry, it contributes essentially to the understanding of corrosion processes. By using selective micro- and nano-sensors, concentration profiles of different corrosion relevant species, from protons to metal ions, can be established. This review provides a comprehensive overview about SECM based techniques and discusses various types of microsensors, including materials selection and preparation techniques, and it provides extensive tables on redox-couples for specific corrosion research applications.
    Materialart: Online-Ressource
    ISSN: 2191-0316
    URL: Article
    DOI: 10.1515/corrrev-2021-0104
    Sprache: Englisch
    Verlag: Walter de Gruyter GmbH
    Publikationsdatum: 2022
    ZDB Id: 2592645-7
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  • 4
    Online-Ressource
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    Involvement of Flagellin in Kin Recognition between Bacillus velezensis Strains
    American Society for Microbiology ; 2022
    In:  mSystems Vol. 7, No. 6 ( 2022-12-20)
    Details
    In: mSystems, American Society for Microbiology, Vol. 7, No. 6 ( 2022-12-20)
    Kurzfassung: Kin discrimination in nature is an effective way for bacteria to stabilize population cooperation and maintain progeny benefits. However, so far, the research on kin discrimination for Bacillus still has concentrated on “attack and defense” between cells and diffusion-dependent molecular signals of quorum sensing, kin recognition in Bacillus , however, has not been reported. To determine whether flagellar is involve in the kin recognition of Bacillus , we constructed Bacillus velezensis SQR9 assembled with flagellin of its kin and non-kin strains, and performed a swarm boundary assay with SQR9, then analyzed sequence variation of flagellin and other flagellar structural proteins in B. velezensis genus. Our results showed that SQR9 assembled with flagellin of non-kin strains was more likely to form a border phenotype with wild-type strain SQR9 in swarm assay than that of kin strains, and that non-kin strains had greater variation in flagellin than kin strains. In B. velezensis , these variations in flagellin were prevalent and had evolved significantly faster than other flagellar structural proteins. Therefore, we proposed that flagellin is an effective tool partly involved in the kin recognition of B. velezensis strains. IMPORTANCE Kin selection plays an important role in stabilizing population cooperation and maintaining the progeny benefits for bacteria in nature. However, to date, the role of flagellin in kin recognition in Bacillus has not been reported. By using rhizospheric Bacillus velezensis SQR9, we accomplished flagellin region interchange among its related strains, and show that flagellin acts as a mediator to distinguish kin from non-kin in B. velezensis . We demonstrated the polymorphism of flagellin in B. velezensis through alignment analysis of flagellin protein sequences. Therefore, it was proposed that flagellin was likely to be an effective tool for mediating kin recognition in B. velezensis .
    Materialart: Online-Ressource
    ISSN: 2379-5077
    URL: Article
    DOI: 10.1128/msystems.00778-22
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2022
    ZDB Id: 2844333-0
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Online-Ressource
    Online-Ressource
    (In situ) Bestimmung des Wasserstoffeintrages in galvanisierten Dualphasenstahl unter korrosiven Bedingungen
    Springer Science and Business Media LLC ; 2023
    In:  BHM Berg- und Hüttenmännische Monatshefte Vol. 168, No. 1 ( 2023-01), p. 15-19
    Details
    In: BHM Berg- und Hüttenmännische Monatshefte, Springer Science and Business Media LLC, Vol. 168, No. 1 ( 2023-01), p. 15-19
    Kurzfassung: Das Ziel dieses Beitrags ist die methodenübergreifende Analyse des Wasserstoffeintrages in feuerverzinkten Dualphasenstahl (DP1000) unter korrosiven Bedingungen. Dazu wurde die Z100 Beschichtung der Proben einer Korrosion durch Immersion in 5 % Natriumchloridlösung bei Raumtemperatur ausgesetzt. The resultierende Wasserstoffverteilung in der Probe sowie Bereiche mit erhöhtem Wasserstoffeintrag konnten mittels Rasterkelvinsonde und Rasterkraft-Kelvinsondenmikroskopie detektiert werden. Die Auswirkung des Wasserstoffs auf die mechanischen Eigenschaften wurde in Langsamzugversuchen analysiert. Die Quantifizierung des eingetragenen Wasserstoffs erfolgte mittels Thermischer Desorptions-Massenspektrometrie, die zusätzlich Einblicke in die Beweglichkeit des Wasserstoffs im Metallgitter ermöglichte, indem zwischen frei beweglichem Wasserstoff und Wasserstoff, immobilisiert in Fallen, unterschieden werden konnte.
    Materialart: Online-Ressource
    ISSN: 0005-8912 , 1613-7531
    URL: Article
    DOI: 10.1007/s00501-022-01314-3
    RVK:
    TE 1000
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2023
    ZDB Id: 2376950-6
    SSG: 19,1
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Online-Ressource
    Online-Ressource
    Assessment of property profile of post‐industrial polypropylene recyclates through a multivariable recycling process
    Wiley ; 2024
    In:  Journal of Applied Polymer Science Vol. 141, No. 31 ( 2024-08-15)
    Details
    In: Journal of Applied Polymer Science, Wiley, Vol. 141, No. 31 ( 2024-08-15)
    Kurzfassung: This study provides key insights into the extrusion of a post‐industrial feedstock primarily composed of polypropylene (PP) and reveals its influence on the property profile of the recyclate. The objective of this study was to gain a fundamental understanding of complex process‐property relationships. Therefore, a two‐part experimental design was established. The first part aimed to analyze the feedstock variability by investigating key material properties of recyclates produced under constant processing conditions. The second part aimed to systematically evaluate the effect of the screw speed, filtration setup, and degassing setup on the properties of the recyclates. An industrial‐scale recycling extrusion line was used. The material evaluation included melt mass‐flow rate (MFR), ash content, oxidation induction temperature, tensile and impact properties, degassing performance, and residual volatile organic compounds (VOCs). Higher melt temperatures led to chain scission of the PP fraction, resulting in increased MFR and higher material stiffness. Additionally, a finer filtration positively contributed to the enhanced material stiffness. Furthermore, the mechanical properties were also influenced by the levels of inorganic fillers in the material composition of the feedstock. Finally, the filtration setup had a greater impact on degassing performance and residual VOC levels than the degassing setup and screw speed.
    Materialart: Online-Ressource
    ISSN: 0021-8995 , 1097-4628
    URL: Issue
    URL: Article
    DOI: 10.1002/app.v141.31
    DOI: 10.1002/app.55731
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2024
    ZDB Id: 1491105-X
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  • 7
    Online-Ressource
    Online-Ressource
    Hydrogen Insertion into Complex-Phase High-Strength Steel during Atmospheric Corrosion at Low Relative Humidity
    MDPI AG ; 2022
    In:  Metals Vol. 12, No. 4 ( 2022-04-04), p. 624-
    Details
    In: Metals, MDPI AG, Vol. 12, No. 4 ( 2022-04-04), p. 624-
    Kurzfassung: Atmospheric corrosion is one of the major sources of hydrogen in a high-strength-steel product in service. Even low concentrations of absorbed hydrogen can cause a hydrogen embrittlement-related material degradation. The extent of atmospheric corrosion and thus the related hydrogen entry is highly dependent on the environmental parameters, such as the relative humidity. The present work focused on the hydrogen entry at low relative humidity, where atmospheric corrosion rates are expected to be low. Hydrogen insertion and distribution in CP1000 steel induced by corrosion under dried and rewetted single droplets of aqueous NaCl and MgCl2 solution were studied using the Scanning Kelvin Probe (SKP) and the resulting amounts of diffusible hydrogen were analyzed using thermal desorption mass spectrometry (TDMS). Corrosion product analyses were carried out with SEM/EDX, XRD, and Mössbauer spectroscopy. The results revealed the strong impact of salt type and concentration on the hydrogen entry into steel. The hygroscopic effect of MgCl2 and the formed corrosion products were responsible for the prolonged insertion of hydrogen into the steel even at very low levels of relative humidity.
    Materialart: Online-Ressource
    ISSN: 2075-4701
    URL: Article
    URL: Article
    DOI: 10.3390/met12040624
    DOI: 10.37473/dac/10.3390/met12040624
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2022
    ZDB Id: 2662252-X
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  • 8
    Online-Ressource
    Online-Ressource
    Critical Assessment of the Effect of Atmospheric Corrosion Induced Hydrogen on Mechanical Properties of Advanced High Strength Steel
    MDPI AG ; 2020
    In:  Metals Vol. 11, No. 1 ( 2020-12-28), p. 44-
    Details
    In: Metals, MDPI AG, Vol. 11, No. 1 ( 2020-12-28), p. 44-
    Kurzfassung: Hydrogen absorption into steel during atmospheric corrosion has been of a strong concern during last decades. It is technically important to investigate if hydrogen absorbed under atmospheric exposure conditions can significantly affect mechanical properties of steels. The present work studies changes of mechanical properties of dual phase (DP) advanced high strength steel specimens with sodium chloride deposits during corrosion in humid air using Slow Strain Rate Test (SSRT). Additional annealed specimens were used as reference in order to separate the possible effect of absorbed hydrogen from that of corrosion deterioration. Hydrogen entry was monitored in parallel experiments using hydrogen electric resistance sensor (HERS) and thermal desorption mass spectrometry (TDMS). SSRT results showed a drop in elongation and tensile strength by 42% and 6%, respectively, in 27 days of atmospheric exposure. However, this decrease cannot be attributed to the effect of absorbed hydrogen despite the increase in hydrogen content with time of exposure. Cross-cut analysis revealed considerable pitting, which was suggested to be the main reason for the degradation of mechanical properties.
    Materialart: Online-Ressource
    ISSN: 2075-4701
    URL: Article
    URL: Article
    DOI: 10.3390/met11010044
    DOI: 10.37473/fic/10.3390/met11010044
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2020
    ZDB Id: 2662252-X
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  • 9
    Online-Ressource
    Online-Ressource
    Versatile, low-cost, non-toxic potentiometric pH-sensors based on niobium
    Elsevier BV ; 2022
    In:  Sensing and Bio-Sensing Research Vol. 35 ( 2022-02), p. 100478-
    Details
    In: Sensing and Bio-Sensing Research, Elsevier BV, Vol. 35 ( 2022-02), p. 100478-
    Materialart: Online-Ressource
    ISSN: 2214-1804
    URL: Article
    DOI: 10.1016/j.sbsr.2022.100478
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2022
    ZDB Id: 2821969-7
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  • 10
    Online-Ressource
    Online-Ressource
    Potential Analysis of the Plastics Value Chain for Enhanced Recycling Rates: A Case Study in Iceland
    MDPI AG ; 2022
    In:  Recycling Vol. 7, No. 5 ( 2022-10-09), p. 73-
    Details
    In: Recycling, MDPI AG, Vol. 7, No. 5 ( 2022-10-09), p. 73-
    Kurzfassung: In light of the circular economy gaining momentum, plastics recycling is regarded as a key solution to keep materials in the loop. Continuous efforts are needed to achieve the packaging waste recycling targets set by the European Union. Hence, this work evaluates the potential of the Icelandic plastics value chain for enhanced recycling rates. In addition to identifying the main challenges and opportunities, a feasibility study was conducted on the expansion of the deposit-return system to Skyr cups, allowing for closed-loop solutions. Based on the status quo, proposals for the improvement of the current waste and recycling system are made. Insights were acquired by semi-structured interviews with nine key stakeholders in Iceland, representing vital groups that influence the plastics value chain. The obtained answers followed the same trend, pointing out that a circular economy within the boundaries of Iceland is currently not feasible. This is mainly due to the strong dependence on international partners in all parts of the value chain except waste collection. However, major improvements are required to enhance the current waste collection rate of 28%. No conclusive evidence was found to justify the suitability of Skyr cups for the deposit-return system, as the disadvantages outweigh theoretically higher collection and recycling rates. Moreover, the extended producer responsibility scheme implemented with the Icelandic Recycling Fund is a valuable tool to enforce a design for recycling of products, enabling higher recycling rates. Despite one recycler operating in Iceland, Icelandic stakeholders consider sorting and treatment of mixed plastic waste as economically more efficient by collaborating with experts throughout Europe. Therefore, they expect that the current practice of exporting the majority of the domestic waste will prevail. On the contrary, the authors propose a comprehensive waste treatment and recycling scheme within Iceland, which requires a sorting step prior to three possible pathways, being (1) mechanical recycling, (2) alternative fuel, and (3) waste-to-energy. The aim of the proposed scheme is a reduction in greenhouse gas impact of plastics entering the waste stage by an efficient and flexible design of the relevant technologies within Iceland.
    Materialart: Online-Ressource
    ISSN: 2313-4321
    URL: Article
    DOI: 10.3390/recycling7050073
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2022
    ZDB Id: 2813991-4
    Standort Signatur Einschränkungen Verfügbarkeit
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