| 1. |
- Andersson, Henrik, Dr, 1975-, et al.
(författare)
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Variable low-density polylactic acid and microsphere composite material for additive manufacturing
- 2021
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Ingår i: Additive Manufacturing. - : Elsevier BV. - 2214-8604 .- 2214-7810. ; 40
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Tidskriftsartikel (refereegranskat)abstract
- Thermally expandable microspheres are extensively used in industry as a lightweight filler for many products. The spheres can expand up to 60 times the initial size and are used for different purposes, including material reduction and surface modification. In fused filament fabrication (FFF), a material is deposited in a layer-by-layer process. Typically, FFF objects need not be solid because such objects are typically used for applications with low mechanical stress. Low material infill percentages are commonly used inside a solid outer shell to reduce material usage, weight, and manufacturing time. This paper proposes a new composite filament for FFF consisting of polylactic acid (PLA) and thermally expandable Expancel microspheres in the form of masterbatch granules. These filaments contain unexpanded microspheres that can be expanded during printing by heating. Two types of filaments containing 2 wt% and 5 wt% of masterbatch granules were manufactured and tested. The filaments were successfully used with a commercial 3D printer to manufacture objects with a density of 45% compared to objects manufactured using standard PLA. The tensile strength of these objects changed linearly with density and was comparable to that of PLA objects of the same density prepared using infill patterns. The composite filaments are advantageous in that they can reduce the amount of material used, as is currently done by using different amounts of infill in a pattern. Further, by varying the nozzle temperature, their density can be adjusted directly during printing as well as during fabrication to produce layers of different densities in the same object.
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| 2. |
- Andres, Britta, 1986-
(författare)
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Low-Cost, Environmentally Friendly Electric Double-Layer Capacitors : Concept, Materials and Production
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Today’s society is currently performing an exit from fossilfuel energy sources. The change to sustainable alternativesrequires inexpensive and environmentally friendly energy storagedevices. However, most current devices contain expensive,rare or toxic materials. These materials must be replaced bylow-cost, abundant, nontoxic components.In this thesis, I suggest the production of paper-based electricdouble-layer capacitors (EDLCs) to meet the demand oflow-cost energy storage devices that provide high power density.To fulfill the requirements of sustainable and environmentallyfriendly devices, production of EDLCs that consist of paper,graphite and saltwater is proposed. Paper can be used as aseparator between the electrodes and as a substrate for theelectrodes. Graphite is suited for use as an active material in theelectrodes, and saltwater can be employed as an electrolyte.Westudied and developed different methods for the productionof nanographite and graphene from graphite. Composites containingthese materials and similar advanced carbon materialshave been tested as electrode materials in EDLCs. I suggest theuse of cellulose nanofibers (CNFs) or microfibrillated cellulose(MFC) as a binder in the electrodes. In addition to improvedmechanical stability, the nanocellulose improved the stabilityof graphite dispersions and the electrical performance of theelectrodes. The influence of the cellulose quality on the electricalproperties of the electrodes and EDLCs was investigated.The results showed that the finest nanocellulose quality is notthe best choice for EDLC electrodes; MFC is recommended forthis application instead. The results also demonstrated thatthe capacitance of EDLCs can be increased if the electrodemasses are adjusted according to the size of the electrolyte ions.Moreover, we investigated the issue of high contact resistancesat the interface between porous carbon electrodes and metalcurrent collectors. To reduce the contact resistance, graphitefoil can be used as a current collector instead of metal foils.Using the suggested low-cost materials, production methodsand conceptual improvements, it is possible to reduce the material costs by more than 90% in comparison with commercialunits. This confirms that paper-based EDLCs are apromising alternative to conventional EDLCs. Our findings andadditional research can be expected to substantially supportthe design and commercialization of sustainable EDLCs andother green energy technologies.
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| 3. |
- Arshadi Rastabi, Shahrzad, et al.
(författare)
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Metallurgical investigation of aluminum anode behavior in water-in-salt electrolyte for aqueous aluminum batteries
- 2022
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Ingår i: Journal of Power Sources. - : Elsevier. - 0378-7753 .- 1873-2755. ; 523
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Tidskriftsartikel (refereegranskat)abstract
- Although ionic liquid electrolytes (ILs) are environmentally unfriendly, they are the most common electrolyte used in aluminum-ion batteries (AIB). Aqueous electrolytes offer a more sustainable alternative, but problem with oxide passivating barrier on Al surface becomes more profound. Recently, a new sub-class of aqueous electrolytes, water-in-salt (WIS) of (AlCl3·6H2O), has been considered, but experimental validation of the behavior of the Al electrode over cycling is required. This work investigates aluminum/graphitic cells using WIS electrolytes with a mass ratio of salt to water of 4, 8, and 12 and finds that they show similar trends in cycling performance. The degradation observed over cycling has been attributed to the formation of a detrimental solid electrolyte interphase (SEI) layer on the Al surface. It was found that WIS 4 increased Al corrosion, resulting in a slightly higher capacity and longer cycling life. Metallurgical observation showed that the Al matrix has a tendency to initiate corrosion around Al3Fe intermetallic phases in both WIS and ILs. This implies that the presence of Al3Fe particles allows the electrolyte to break the oxide barrier and access the bulk Al. These results suggests that metallurgical treatments are important to enhance the electrochemical performance of AIB.
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| 4. |
- Arshadi Rastabi, Shahrzad, et al.
(författare)
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Porous NiMoO4-NrGO as a Battery-Like Electrode Material for Aqueous Hybrid Supercapacitors
- 2023
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Ingår i: Journal of Composites Science. - : MDPI. - 2504-477X. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- Recently, much research has investigated nanocomposites and their properties for the development of energy storage systems. Supercapacitor performance is usually enhanced by the use of porous electrode structures, which produce a larger surface area for reaction. In this work, a biocompatible polymer of starch medium was used to create the porous nanostructure. Two powders, i.e., Nickel molybdate/reduced graphene oxide (NiMoO4-rGO) and Nickel molybdate/nitrogen-doped reduced graphene oxide (NiMoO4-NrGO), were synthesized using the deposition method in a medium containing starch, nickel nitrate salts, sodium molybdate, and graphene oxide powder. In terms of electrochemical performance, the NiMoO4-NrGO electrode displayed a higher specific capacitance, i.e., 932 Fg−1 (466 Cg−1), than the NiMoO4-rGO electrode, i.e., 884 Fg−1 (442 Cg−1), at a current density of 1 Ag−1. In fact, graphene oxide sheets could lose more oxygen groups in the presence of ammonia, resulting in increased electrical conductivity. For the asymmetric supercapacitor of NiMoO4-NrGO//AC, the specific capacitance at 1 Ag−1, energy density, and power density were 101.2 Fg−1 (111.32 Cg−1), 17 Wh kg−1, and 174.4 kW kg−1, respectively. In addition, this supercapacitor material displayed a good cycling stability of over 82%.
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| 5. |
- Bond, Luke, et al.
(författare)
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Electrically conductive polymer-graphene composite material for selective laser sintering additive manufacturing
- 2024
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE - The International Society for Optics and Photonics. - 9781510670068
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Konferensbidrag (refereegranskat)abstract
- Additive manufacturing is rapidly growing, where selective laser sintering technology dominates for industrial use. In the case of polymer selective laser sintering, polyamide is the standard material. However, polyamide is an electrical insulator, and for specific applications, it would be desirable to be able to manufacture polymer-based electrically conductive parts. Electromagnetic Compatibility is one of the most significant targeted applications, where the introduction of electric vehicles raises new electromagnetic compatibility demands. The goal is, therefore, to develop an electrically conductive composite material for selective laser sintering using graphene as the additive. Composites are prepared by mixing polyamide, graphene, and additives with varying graphene/polyamide ratios. The aim of this investigation is the laser-assisted processing of the resulting graphene/polyamide composites with various parameters to sinter the material, forming a solid conductive structure. The structure is characterized using SEM and resistance measurements. Results show sheet resistance values of about 700Ω/sq after laser-assisted processing with good powder flowability.
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| 6. |
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| 7. |
- Ebadi, Seyed Morteza, et al.
(författare)
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A Highly-Efficient and Compact Surface Plasmon Polaritons High-Pass Filter based on MIM waveguides
- 2020
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Ingår i: <em>Frontiers in Optics / Laser Science</em>. - Washington, D.C., United States : Optics Info Base, Optical Society of America. - 9781943580804 ; , s. 1-2
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Konferensbidrag (refereegranskat)abstract
- This letter presents design and simulation results of a highly-efficient and compact plasmonic high-pass filter based on a MIM waveguide. Numerical results reveal that by tailoring structural parameters, desired cut-off wavelength can be chosen.
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| 8. |
- Ebadi, Seyed Morteza, et al.
(författare)
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A Multipurpose and Highly-Compact Plasmonic Filter based on Metal-Insulator-Metal Waveguides
- 2020
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Ingår i: IEEE Photonics Journal. - 1943-0655. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- A multipurpose and ultra-compact nanoplasmonic wavelength filter based on stub structure in a metal-insulator-metal (MIM) waveguide is suggested and numerically investigated. A novel approach of connecting two stepped-like apertures to both input and output ports is applied to form Fabry-Perot (FP) cavities, which enabled the structure to act as a dual band-pass filter at wavelengths 1310 nm and 1550 nm. It is shown that the variation in cavities’ length allows to realize a long-wavelength cutoff filter, and cutoff wavelength can be easily tuned by adjusting the length of the cavities. Furthermore, it is revealed that increasing the gap between the stepped-like apertures and the cavities provides a triple band-pass at telecom wavelengths, e.g. 1267.5nm, 1414.19 nm, and 1644.7 nm. The tunable broadband high-pass wavelength filter is then achieved while the lengths of stepped-like apertures and stub resonators are set to be identical. Finally, a tunable nearly perfect absorber can be obtained by varying the width of stub resonators. Therefore, because of functionality, size, as well as efficiency the proposed plasmonic filter may greatly contribute to miniaturization of next generation of photonic integrated circuits (PICs), and find applications in on-chip integration and wavelength-division multiplexing (WDM) in optical communication systems.
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| 9. |
- Ebadi, Seyed Morteza, et al.
(författare)
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A Reconfigurable and Ultra-Compact Plasmonic Filter based on MIM Waveguides at Optical Channels
- 2020
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Ingår i: <em>OSA Advanced Photonics Congress (AP) 2020</em>. - : Optics Info Base, Optical Society of America. - 9781943580798
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Konferensbidrag (refereegranskat)abstract
- This paper reports design and simulation of a tunable highly-efficient reconfigurableplasmonic filter based on MIM waveguides. Simulation results shown that by adjusting structuralparameters, the device can work as a multipurpose optical circuit.
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| 10. |
- Ebadi, Seyed Morteza, et al.
(författare)
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A Tunable and Highly-Efficient Plasmonic Band-Stop Filter at Telecom Wavelengths
- 2021
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Ingår i: 2021 IEEE Research and Applications of Photonics in Defense Conference (RAPID). - Miramar Beach, FL, USA : Institute of Electrical and Electronics Engineers (IEEE). - 9781665446747 - 9781665422239 ; , s. 1-2
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Konferensbidrag (refereegranskat)abstract
- This paper reports design and numerical results of an ultra-compact, efficient and tunable plasmonic band-stop filter based on a metal-insulator-metal waveguide at optical channels. Furthermore, a wide-bandgap can be easily achieved by adjusting the width of the of the stub resonator.
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