@article{4372, abstract = {Magnetic nanofibers were prepared by electrospinning polymer/metal solutions of poly(acrylonitrile) (PAN) with magnetite (Fe3O4) nanoparticles. At a mass ratio of PAN:magnetite of 2:1, the total solid content in the dimethyl sulfoxide (DMSO) solution was varied between 15 wt.% and 25 wt.%, which represents the limits of the spinnable range. The results show that the most homogeneous nanofiber mats were 21 wt.% solid contents. At 15 wt.% solid contents, a nano-membrane with some fibrous regions was produced. Nanofibers at 25 wt.% had a much larger and more inhomogeneous diameter. Nevertheless, the magnetic properties of all samples were very similar, indicating that the distribution of magnetite nanoparticles in the fibers is comparable in all samples. The results also suggested that the samples spun from solutions with near-ideal solid contents (19–21 wt.%) contain agglomerations of the nanoparticles inside the nanofibers. }, author = {Graciano Alvarez, Ana Karen and Dotter, Marius and Tuvshinbayar, Khorolsuren and Bondzio, Laila and Ennen, Inga and Hütten, Andreas and Blachowicz, Tomasz and Ehrmann, Andrea}, issn = {2079-6439}, journal = {Fibers}, keywords = {electrospinning, magnetite, homogeneity, fiber diameter, alternating gradient magnetometer (AGM)}, number = {3}, publisher = {MDPI AG}, title = {{Electrospinning Poly(acrylonitrile) Containing Magnetite Nanoparticles: Influence of Magnetite Contents}}, doi = {10.3390/fib12030019}, volume = {12}, year = {2024}, } @article{3758, abstract = { The increasing development and application of wireless devices and systems that radiate electromagnetic waves makes electromagnetic interference (EMI) shielding more and more important in everyday life. In practice, rigid EMI shields are the most commonly used ones. However, for humans or in automotive and aviation applications, flexible, drapable materials, such as textile fabrics, can be more effective and useful. Textile fabrics are usually nonconductive and not magnetic, i.e., they lack the requirements for EMI shielding. However, shielding properties of textile fabrics can be achieved by blending yarns with fine wires or coating fibers or by blending complete textile layers with conductive or magnetic materials. In this paper, shielding textile fabrics and 3D-printed materials, as references with different conductive (and partly also magnetic) properties, are examined. The measurements show a high shielding effectiveness of 80 dB given by densely woven fabrics with a thin metallic coating in the frequency range of 6.5–11 GHz, while large pores in crocheted fabrics significantly reduce the EMI shielding effectiveness, and other samples did not show shielding at all, suggesting that a combination of conductivity and the structure of the samples is responsible for the shielding potential. }, author = {Wójcik, Dariusz and Surma, Maciej and Magnuski, Mirosław and Blachowicz, Tomasz and Tuvshinbayar, Khorolsuren and Dotter, Marius and Topuz, Yusuf and Ehrmann, Andrea}, issn = {2076-3417}, journal = {Applied Sciences}, keywords = {electromagnetic interference (EMI), shielding effectiveness, conductive coating, metallized fabric, conductive yarn, crocheted fabric, porosity, cover factor}, number = {17}, publisher = {MDPI AG}, title = {{Experimental Verification of the Shielding Properties of Selected Textile Materials in the X Frequency Band}}, doi = {10.3390/app13179777}, volume = {13}, year = {2023}, } @article{3747, abstract = { A first limited approach for the automated production of crocheted fabrics was introduced in 2019. However, the knowledge on crocheted fabrics is very scarce and only few technical applications are presented in the literature. To provide a basis for possible future technical applications, the general tensile properties of crocheted fabrics are explored, and a promising application as composite reinforcement is introduced. Due to the early development state of the crochet machine prototype, conventionally hand-made crocheted fabrics are studied and the benefit of improving the machine is evaluated. The mechanical properties of crocheted fabrics depend significantly on the individual crocheter, but fabrics produced from the same person are sufficiently reproducible for reasonable investigations. Anisotropic properties with a trend toward higher resisted forces in course compared to wale direction were identified with crochets constructed from single crochet (sc) and from half double crochet (hdc) stitches. Furthermore, a tendency toward higher possible loads at larger elongations was revealed for crocheted fabrics compared to knitted ones. To the best of our knowledge, for the first time crocheted aramid fabrics were used in epoxy composites. With a crocheted reinforcement in a non-cut composite produced by vacuum-assisted hand lay-up, significantly higher ultimate tensile strength and Young’s modulus were recorded compared to a knitted one with comparable fracture modes. }, author = {Storck, Jan Lukas and Steenbock, Liska and Dotter, Marius and Funke, Herbert and Ehrmann, Andrea}, issn = {1558-9250}, journal = {Journal of Engineered Fibers and Fabrics}, publisher = {SAGE Publications}, title = {{Principle capabilities of crocheted fabrics for composite materials}}, doi = {10.1177/15589250231203381}, volume = {18}, year = {2023}, } @article{3595, abstract = {Nanofiber mats can be electrospun by different techniques, usually subdivided into needle-based and needleless. The latter allow for producing large-area nanofiber mats, e.g., with a width of 50 cm and lengths of several meters, if electrospinning proceeds for several hours, depending on the required thickness. Even spinning smaller samples, however, raises the question of homogeneity, especially if defined mechanical properties or a defined thickness is required, e.g., for filtration purposes. Very often, only the inner parts of such electrospun nanofiber mats are used to avoid too high variation of the nanofiber mat thickness. For this study, we used wire-based electrospinning to prepare nanofiber mats with slightly varying spinning parameters. We report investigations of the thickness and mass per unit area, measured on different positions of needleless electrospun nanofiber mats. Martindale abrasion tests on different positions are added as a measure of the mechanical properties. All nanofiber mats show unexpectedly strong variations of thickness, mass per unit area, and porosity, as calculated from the apparent density of the membranes. The thickness especially varied by nearly one order of magnitude within one sample, while the apparent density, as the most uniform parameter, still showed variations by more than a factor of two within one sample. This shows that even for apparently highly homogeneous areas of such nanofiber mats, variations cannot be neglected for all potential applications. }, author = {Morina, Edona and Dotter, Marius and Döpke, Christoph and Kola, Ilda and Spahiu, Tatjana and Ehrmann, Andrea}, issn = {2079-4991}, journal = {Nanomaterials}, number = {18}, publisher = {MDPI AG}, title = {{Homogeneity of Needleless Electrospun Nanofiber Mats}}, doi = {10.3390/nano13182507}, volume = {13}, year = {2023}, } @article{3301, abstract = { Dye-sensitized solar cells have been under development for the last three decades but are yet to see the market. This has been attributed to stability issues of the electrolyte in the cell. Electrolytes can be liquid, quasi-solid, or solid. Liquid electrolytes were the first to be developed and, therefore, have been subject to radical revisions in both composition and applicability. They have shown the best power conversion efficiencies but have poor thermal stability. Although quasi-solid and solid-state electrolytes were developed to overcome these stability issues, they too have their limits. The aim of this paper is to explore the development of liquid electrolytes, outlining the current state of the technology and considering their potential in the photovoltaic market. }, author = {Ebenezer Anitha, Angellina and Dotter, Marius}, issn = {1996-1073}, journal = {Energies}, number = {13}, publisher = {MDPI AG}, title = {{A Review on Liquid Electrolyte Stability Issues for Commercialization of Dye-Sensitized Solar Cells (DSSC)}}, doi = {10.3390/en16135129}, volume = {16}, year = {2023}, } @article{2577, abstract = { In the context of the energy transition to renewables, the spotlight is on large systems connected to the power grid, but this also offers room for smaller, more specialized applications. Photovoltaics, in particular, offer the possibility of the self-sufficient supply of smaller electrical appliances on smaller scales. The idea of making previously unused surfaces usable is by no means new, and textiles such as backpacks, tent tarpaulins and other covers are particularly suitable for this purpose. In order to create a non-toxic and easily recyclable product, dye-sensitized solar cells (DSSC), which can be manufactured through electrospinning with a textile feel, are an attractive option here. Therefore, this paper investigates a needle electrospun nanofiber mat, whose spin solution contains polyacrylonitrile (PAN) dissolved in dimethyl sulfoxide (DMSO) as well es TiO2 nanoparticles. In addition to characterization, the nanofiber mat was dyed in a solution containing anthocyanins to later serve as a front electrode for a dye-sensitized solar cell. Although of lower efficiency, the DSSC provides stable results over two months of measurement. }, author = {Dotter, Marius and Placke, Lion Lukas and Storck, Jan Lukas and Güth, Uwe}, issn = {2350-3696}, journal = {Tekstilec}, keywords = {dye-sensitized solar cells (DSSC), long-term stability, electrospinning, polyacrylonitrile (PAN), TiO2 nanoparticles}, number = {4}, pages = {298--306}, publisher = {University of Ljubljana}, title = {{Characterization of PAN-TiO2 Nanofiber Mats and their Application as Front Electrodes for Dye-sensitized Solar Cells}}, doi = {10.14502/tekstilec.65.2022081}, volume = {65}, year = {2023}, } @article{2285, abstract = {Long-term stability belongs to the main problems of dye-sensitized solar cells (DSSCs), impeding their practical application. Especially the usually fluid electrolyte tends to evaporation, thus drying the cells if they are not perfectly sealed. While gelling the electrolyte with different polymers often reduces the efficiency, using a glycerol-based electrolyte was already shown to result in similar or even improved efficiency. At the same time, drying of the cells was significantly reduced. Here we report on improving glycerol-based electrolytes further by varying the iodine-triiodide ratio and the overall concentration in the electrolyte. Long-term tests with unsealed glass-based DSSCs were performed over more than 1 year, showing that most of the cells increased efficiency during this time, opposite to cells with a commercial solvent-based iodine-triiodide electrolyte which completely dried after 2–3 months.}, author = {Gossen, Katrin and Dotter, Marius and Brockhagen, Bennet and Storck, Jan Lukas and Ehrmann, Andrea}, journal = {AIMS Materials Science }, keywords = {dye-sensitized solar cells (DSSCs), glycerol, electrolyte, iodine-triiodide, natural dye, long-term study}, number = {2}, pages = {283--296}, title = {{Long-term investigation of unsealed DSSCs with glycerol-based electrolytes of different compositions}}, doi = {10.3934/matersci.2022017}, volume = {9}, year = {2022}, } @article{2029, abstract = { Keratin is one of the most important protein materials and can act as a sustainable biopolymer for manifold applications. This paper reports on a sustainable extraction method for keratin from wool fiber materials. The use of this extracted keratin for polymer film preparation and preparation of nano-composite materials by electrospinning is investigated. The preparation of keratin films is done in combination with the both biopolymers alginate and pectin. Keratin nanofibers are prepared in combination with the polymer polyacrylonitrile PAN. A view on antibacterial properties of the prepared films is given. As further analytic methods, Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetry, and scanning electron microscopy (SEM) are used. Finally, the preparation of new keratin containing materials is described, which may be used in future for biomedical applications. }, author = {Goyal, Sahil and Dotter, Marius and Diestelhorst, Elise and Storck, Jan Lukas and Ehrmann, Andrea and Mahltig, Boris}, issn = {1558-9250}, journal = {Journal of Engineered Fibers and Fabrics}, keywords = {Keratin, wool, electrospinning, SEM, FT-IR spectroscopy, antimicrobial, antibacterial}, publisher = {SAGE Publications}, title = {{Extraction of keratin from wool and its use as biopolymer in film formation and in electrospinning for composite material processing}}, doi = {10.1177/15589250221090499}, volume = {17}, year = {2022}, } @article{1412, abstract = { In times of climate change and dwindling fossil resources, the need for sustainable renewable energy technologies gains importance, increasingly fast. However, the state of the art technologies are energy intensive in their production, like monocrystalline photovoltaic, or even consist of not recyclable composite material, in the case of wind turbine blades. Despite a lack in efficiency and stability, dye sensitized solar cells (DSSC) have a high potential to supplement the state of the art green energy technology in future. With low production costs and no necessity for toxic compounds DSSCs are a potential product, which could circulate in the loops of a circular economy. Therefore, with this paper, we provide the status of research on DSSC recycling and an outlook on how recycling streams could be realized in the future for glass-based DSSCs without toxic components. The overview includes work on using recycled material to build DSSCs and extending the life of a DSSC, e.g., through rehydration. We also illustrate the state of sustainability research for DSSCs using the VOSviewer tool. To date, the term sustainability appears in 35 of 24,441 publications on DSSCs. In view of the global challenges, sustainability should be researched more seriously because it is as important as the efficiency and stability of DSSCs. }, author = {Schoden, Fabian and Dotter, Marius and Knefelkamp, Dörthe and Blachowicz, Tomasz and Schwenzfeier-Hellkamp, Eva}, issn = {1996-1073}, journal = {Energies}, number = {13}, publisher = {MDPI AG}, title = {{Review of State of the Art Recycling Methods in the Context of Dye Sensitized Solar Cells}}, doi = {10.3390/en14133741}, volume = {14}, year = {2021}, } @article{2169, abstract = { The electrolyte for dye-sensitized solar cells (DSSCs) is subject of constant innovation, as the problems of leakage and drying greatly reduce the long-term stability of a device. One possible way to solve these problems is the use of gel polymer electrolytes (GPEs) with a gelling structure, which offer different advantages based on the used polymers. Here, potential GPE systems based on dimethyl sulfoxide (DMSO) as solvent for low-cost, non-toxic and environmentally friendly DSSCs were investigated comparatively. In order to observe a potential improvement in long-term stability, the efficiencies of DSSCs with different GPEs, consisting of polyacrylonitrile (PAN), acrylonitrile-butadiene-styrene (ABS), polyvinyl alcohol (PVA) and poly (vinylidene fluoride) (PVDF) and their blends with poly (ethylene oxide) (PEO), were investigated over a period of 120 days. The results indicate that blending the polymers with PEO achieves better results concerning long-term stability and overall efficiency. Especially the mixtures with PAN and PVDF show only slight signs of deterioration after 120 days of measurement. }, author = {Dotter, Marius and Storck, Jan Lukas and Surjawidjaja, Michelle and Adabra, Sonia and Grothe, Timo}, issn = {2076-3417}, journal = {Applied Sciences}, number = {13}, publisher = {MDPI AG}, title = {{Investigation of the Long-Term Stability of Different Polymers and Their Blends with PEO to Produce Gel Polymer Electrolytes for Non-Toxic Dye-Sensitized Solar Cells}}, doi = {10.3390/app11135834}, volume = {11}, year = {2021}, } @article{1082, abstract = { Alongside efficiency, long-term stability of dye-sensitized solar cells (DSSCs) is a key factor regarding their commercialization. One suitable and cost-effective method to increase the long-term stability is to prevent leakage and evaporation of the electrolyte by gelling it with polymers such as poly(ethylene oxide) (PEO) and gaining a gel polymer electrolyte (GPE). In this study, a GPE based on PEO and glycerol is investigated for the first time as electrolyte for environmentally friendly DSSCs with natural dyes. To evaluate the novel glycerol/PEO GPE, the ionic conductivity and resulting efficiency progressions of DSSCs were measured for 75 days. Different molecular weights (MWs) of PEO and blending with poly(vinylidene fluoride) (PVDF) had negligible impact on efficiencies. 17 wt% PEO was found to be more suitable than lower concentrations and resulted in a relatively high efficiency over 75 days. A glycerol electrolyte without PEO had higher ionic conductivity and achieved higher efficiencies as well but leaked from the unsealed DSSCs. In addition, the reproducibility was examined especially, which appeared to be reduced by considerable differences between identical DSSCs and between measurements of the same DSSC at different times. This emphasizes the relevance of studying multiple DSSC per sample to ensure reliable results. }, author = {Storck, Jan Lukas and Dotter, Marius and Brockhagen, Bennet and Grothe, Timo}, issn = {2073-4352}, journal = {Crystals}, number = {12}, publisher = {MDPI AG}, title = {{Evaluation of Novel Glycerol/PEO Gel Polymer Electrolytes for Non-Toxic Dye-Sensitized Solar Cells with Natural Dyes Regarding Long-Term Stability and Reproducibility}}, doi = {10.3390/cryst10121158}, volume = {10}, year = {2020}, } @article{1083, abstract = { To overcome the long-term stability problems of dye-sensitized solar cells (DSSC) due to solvent evaporation and leakage, gelling the electrolyte with polymers is an appropriate option. Especially for future applications of textile-based DSSCs, which require cost-effective and environmentally friendly materials, such an improvement of the electrolyte is necessary. Therefore, the temporal progressions of efficiencies and fill factors of non-toxic glass-based DSSCs resulting from different gel electrolytes with poly(ethylene oxide) (PEO) are investigated over 52 days comparatively. Dimethyl sulfoxide (DMSO) proved to be a suitable non-toxic solvent for the proposed gel electrolyte without ionic liquids. A PEO concentration of 17.4 wt% resulted in an optimal compromise with a relatively high efficiency over the entire period. Lower concentrations resulted in higher efficiencies during the first days but in a poorer long-term stability, whereas a higher PEO concentration resulted in an overall lower efficiency. Solvent remaining in the gel electrolyte during application was found advantageous compared to previous solvent evaporation. In contrast to a commercial liquid electrolyte, the long-term stability regarding the efficiency was improved successfully with a similar fill factor and thus equal quality. }, author = {Storck, Jan Lukas and Dotter, Marius and Adabra, Sonia and Surjawidjaja, Michelle and Brockhagen, Bennet and Grothe, Timo}, issn = {2073-4360}, journal = {Polymers}, number = {12}, publisher = {MDPI AG}, title = {{Long-Term Stability Improvement of Non-Toxic Dye-Sensitized Solar Cells via Poly(ethylene oxide) Gel Electrolytes for Future Textile-Based Solar Cells}}, doi = {10.3390/polym12123035}, volume = {12}, year = {2020}, } @article{680, abstract = {Polyacrylonitrile (PAN) belongs to the group of polymers that are often used for electrospinning, as it can be applied as a pre-cursor for carbon nanofibers and is spinnable from the low-toxic solvent dimethyl sulfoxide (DMSO). While the influence of different spinning parameters on fibre morphology and mass per unit area was investigated in a previous study, here we report on the impact of the spinning solution, using DMSO as a solvent and wire-based (needleless) electrospinning. Our results show that a broad range of solid contents can be applied, providing the opportunity to tailor the fibre diameter distribution or to optimize the areal weight of the nanofibrous mat by changing this parameter, while the chemical composition of the fibres remains identical.}, author = {Grothe, Timo and Storck, Jan Lukas and Dotter, Marius and Ehrmann, Andrea}, journal = {Tekstilec}, keywords = {needleless electrospinning, polyacrylonitrile (PAN), nanofibrous mat, dimethyl sulfoxide (DMSO), Fourier-transform infrared (FTIR) spectroscopy}, number = {3}, pages = {225--232}, title = {{Impact of solid content in the electrospinning solution on the physical and chemical properties of polyacrylonitrile (PAN) nanofibrous mats}}, doi = {10.14502/Tekstilec2020.63.225-232}, volume = {63}, year = {2020}, }