| 1. |
- Jönsson, Christina, et al.
(författare)
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Biocatalysis in the Recycling Landscape for Synthetic Polymers and Plastics towards Circular Textiles
- 2021
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 14:19, s. 4028-4040
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Tidskriftsartikel (refereegranskat)abstract
- Although recovery of fibers from used textiles with retained material quality is desired, separation of individual components from polymer blends used in today's complex textile materials is currently not available at viable scale. Biotechnology could provide a solution to this pressing problem by enabling selective depolymerization of recyclable fibers of natural and synthetic origin, to isolate constituents or even recover monomers. We compiled experimental data for biocatalytic polymer degradation with a focus on synthetic polymers with hydrolysable links and calculated conversion rates to explore this path The analysis emphasizes that we urgently need major research efforts: beyond cellulose-based fibers, biotechnological-assisted depolymerization of plastics so far only works for polyethylene terephthalate, with degradation of a few other relevant synthetic polymer chains being reported. In contrast, by analyzing market data and emerging trends for synthetic fibers in the textile industry, in combination with numbers from used garment collection and sorting plants, it was shown that the use of difficult-to-recycle blended materials is rapidly growing. If the lack of recycling technology and production trend for fiber blends remains, a volume of more than 3400 Mt of waste will have been accumulated by 2030. This work highlights the urgent need to transform the textile industry from a biocatalytic perspective.
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| 2. |
- Hosseini, Seyedehsan, 1994
(författare)
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Additive-Driven Improvements in Interfacial Properties and Processing of TMP-Polymer Composites
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Efforts to address environmental concerns have resulted in new regulations designed to plan the reduction of plastic and synthetic polymer usage, necessitating the search for sustainable natural alternatives with comparable cost-effectiveness and mechanical performance. Thermomechanical pulp (TMP) fibres are one of the most affordable natural fibres that have no chemical refining in production, production have a high yield of 90-98% and TMP fibres have been demonstrated to improve the mechanical characteristics (strength, stiffness and toughness) of wood-polymer composites (WPCs) compared to the pure polymer. The integration of TMP fibres with non-polar synthetic polymers remains a challenge due to surface polarity differences. This PhD thesis aims to ease the processing of TMP fibre composites through the incorporation of additives. The hypothesis posits that incorporating magnesium stearate (MgSt), molybdenum disulfide (MoS2) and alkyl ketene dimer (AKD) as additives in TMP composites will enhance interfacial properties, resulting in improved processability and flow behaviour at high temperatures. MoS2 is known for its interaction with lignin, which exists in TMP and MgSt is recognised for its ability to improve flow in pharmaceutical processing when combined with cellulose, also a component of TMP. AKD modifies the hydrophilic properties of lignocellulosic surfaces. The experimental work explores the effect of these additives on the properties of TMP composites of ethylene acrylic acid copolymer (EAA) and polypropylene (PP) matrices. The dynamic mechanical analysis (DMA) and mechanical analysis results reveal that MoS2 exhibits superior interaction with TMP fibres, yielding enhanced interfacial properties compared to MgSt in between EAA and TMP fibres. Rheological studies elucidate the transition from a fluid-like state to a network-like structure upon the incorporation of TMP into the PP matrix. The incorporation of AKD with C18 reduces the viscosity of TMP-PP composites and PP itself, and, as determined through theoretical Hansen solubility parameter (HSP) calculations, increases compatibility between cellulose in TMP fibres and PP. The addition of AKD influences both the colour (lighter) and shape (smoother surface) of the extrudate filaments in the TMP-PP composites, indicative of improved processing. In addition, frictional analysis demonstrates the reduction of the coefficient of friction (COF) between metal and TMP fibre by MgSt and AKD treatments.
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| 3. |
- Lei, Yu, et al.
(författare)
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Graphene and Beyond: Recent Advances in Two-Dimensional Materials Synthesis, Properties, and Devices
- 2022
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Ingår i: ACS Nanoscience Au. - : American Chemical Society (ACS). - 2694-2496. ; 2:6, s. 450-485
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Forskningsöversikt (refereegranskat)abstract
- Since the isolation of graphene in 2004, two-dimensional (2D) materials research has rapidly evolved into an entire subdiscipline in the physical sciences with a wide range of emergent applications. The unique 2D structure offers an open canvas to tailor and functionalize 2D materials through layer number, defects, morphology, moiré pattern, strain, and other control knobs. Through this review, we aim to highlight the most recent discoveries in the following topics: theory-guided synthesis for enhanced control of 2D morphologies, quality, yield, as well as insights toward novel 2D materials; defect engineering to control and understand the role of various defects, including in situ and ex situ methods; and properties and applications that are related to moiré engineering, strain engineering, and artificial intelligence. Finally, we also provide our perspective on the challenges and opportunities in this fascinating field.
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| 4. |
- Hosseini, Seyedehsan, 1994, et al.
(författare)
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Alkyl ketene dimer modification of thermomechanical pulp promotes processability with polypropylene
- 2024
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Ingår i: Polymer Composites. - 1548-0569 .- 0272-8397. ; 45:1, s. 825-835
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Tidskriftsartikel (refereegranskat)abstract
- Alkyl ketene dimers (AKDs) are known to efficiently react with cellulose with a dual polarity in their structure: a polar component and a nonpolar component. AKD of three different carbon chain lengths, 4, 10, and 16 carbons have been synthesized, and thermomechanical pulp (TMP) fibers were modified by them. The modification of TMP fibers with AKD resulted in an increased water contact angle, showing the presence of the AKDs on the TMP fibers and a new carbonyl peak in the IR spectra, suggesting modification of the TMP fibers with AKD groups. Calculating the Hansen solubility parameters of AKD and AKD conjugated to TMP in polypropylene (PP) indicates improved compatibility, especially of longer chain AKD and TMP AKD. The rheological studies of the composites showed that the AKD with the longest carbon chain decreases the melt viscosity of the PP-TMP-AKD composite, which combined with the shape and the color of the extruded composite filaments indicates improved flow properties and reduced stress build up during processing. The research findings demonstrate the ability of AKD to enhance the dispersibility and compatibility of natural fibers with PP.
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| 5. |
- Townsend, Philip, 1991, et al.
(författare)
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Stochastic modelling of 3D fiber structures imaged with X-ray microtomography
- 2021
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Ingår i: Computational materials science. - : Elsevier B.V.. - 0927-0256 .- 1879-0801. ; 194
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Tidskriftsartikel (refereegranskat)abstract
- Many products incorporate into their design fibrous material with particular levels of permeability as a way to control the retention and flow of liquid. The production and experimental testing of these materials can be expensive and time consuming, particularly if it needs to be optimised to a desired level of absorbency. We consider a parametric virtual fiber model as a replacement for the real material to facilitate studying the relationship between structure and properties in a cheaper and more convenient manner. 3D image data sets of a sample fibrous material are obtained using X-ray microtomography and the individual fibers isolated. The segmented fibers are used to estimate the parameters of a 3D stochastic model for generating softcore virtual fiber structures. We use several spatial measures to show the consistency between the real and virtual structures, and demonstrate with lattice Boltzmann simulations that our virtual structure has good agreement with respect to the permeability of the physical material. © 2021 The Author(s)
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| 6. |
- Peterson, Joel, 1959-, et al.
(författare)
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Mechanical-Property-Based Comparison of Paper Yarn with Cotton, Viscose, and Polyester Yarns
- 2021
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Ingår i: Journal of Natural Fibers. - : Taylor & Francis Group. - 1544-0478 .- 1544-046X. ; 18:4, s. 492-501
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Tidskriftsartikel (refereegranskat)abstract
- Cotton and oil-based fibre consumption is highly problematic because the growth of these materials often requires fertilisers and toxic pesticides. Less environmentally damaging alternative fibres are urgently required. This study investigates Manila-hemp paper-yarn textile fabrics. Manila-hemp (abacá) is a species of banana grown as a commercial crop in the Philippines, Ecuador, and Costa Rica. Knitted structures of paper, cotton, viscose, and polyester yarns are tested and compared. Tensile strength tests are also performed. Paper yarn shows low shrinkage and no pilling, which are excellent characteristics for use in the textile and clothing industries. However, its poor handleability/knittability, high stiffness, and hard grip must be resolved for the widespread application of paper yarn in the textile industry in the future.
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| 7. |
- Hu, Enyi, et al.
(författare)
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Junction and energy band on novel semiconductor-based fuel cells
- 2021
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Ingår i: iScience. - : Elsevier BV. - 2589-0042. ; 24:3
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Forskningsöversikt (refereegranskat)abstract
- Fuel cells are highly efficient and green power sources. The typical membrane electrode assembly is necessary for common electrochemical devices. Recent research and development in solid oxide fuel cells have opened up many new opportunities based on the semiconductor or its heterostructure materials. Semiconductor-based fuel cells (SBFCs) realize the fuel cell functionality in a much more straightforward way. This work aims to discuss new strategies and scientific principles of SBFCs by reviewing various novel junction types/interfaces, i.e., bulk and planar p-n junction, Schottky junction, and n-i type interface contact. New designing methodologies of SBFCs from energy band/alignment and built-in electric field (BIEF), which block the internal electronic transport while assisting interfacial superionic transport and subsequently enhance device performance, are comprehensively reviewed. This work highlights the recent advances of SBFCs and provides new methodology and understanding with significant importance for both fundamental and applied R&D on new-generation fuel cell materials and technologies.
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| 8. |
- Zubritskaya, Irina, 1984, et al.
(författare)
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Dynamically Tunable Optical Cavities with Embedded Nematic Liquid Crystalline Networks
- 2023
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 35:13
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Tidskriftsartikel (refereegranskat)abstract
- Tunable metal–insulator–metal (MIM) Fabry–Pérot (FP) cavities that can dynamically control light enable novel sensing, imaging and display applications. However, the realization of dynamic cavities incorporating stimuli-responsive materials poses a significant engineering challenge. Current approaches rely on refractive index modulation and suffer from low dynamic tunability, high losses, and limited spectral ranges, and require liquid and hazardous materials for operation. To overcome these challenges, a new tuning mechanism employing reversible mechanical adaptations of a polymer network is proposed, and dynamic tuning of optical resonances is demonstrated. Solid-state temperature-responsive optical coatings are developed by preparing a monodomain nematic liquid crystalline network (LCN) and are incorporated between metallic mirrors to form active optical microcavities. LCN microcavities offer large, reversible and highly linear spectral tuning of FP resonances reaching wavelength-shifts up to 40 nm via thermomechanical actuation while featuring outstanding repeatability and precision over more than 100 heating–cooling cycles. This degree of tunability allows for reversible switching between the reflective and the absorbing states of the device over the entire visible and near-infrared spectral regions, reaching large changes in reflectance with modulation efficiency ΔR = 79%.
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| 9. |
- Öberg Månsson, Ingrid, 1991-
(författare)
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Electroanalytical devices with fluidic control using textile materials and methods
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis, written by Ingrid Öberg Månsson at KTH Royal Institute of Technology and entitled “Electroanalytical devices with fluidic control using textile materials and methods”, presents experimental studies on the development of textile based electronic devices and biosensors. One of the reasons why this is of interest is the growing demand for integrated smart products for wearable health monitoring or energy harvesting. To enable such products, new interdisciplinary fields arise combining traditional textile technology and electronics.Textile based devices have garnered much interest in recent years due to their innate ability to incorporate function directly into, for example, clothing or bandages by textile processes such as weaving, knitting or stitching. However, many modifications of yarns required for such applications are not available on an industrial scale. The major objective of this work has been to study how to achieve the performance necessary to create electronic textile devices by either coating yarns with conductive material or using commercially available conductive yarns that are functionalized to create sensing elements.Further, liquid transport within textile materials has been studied to be able to control the contact area between electrolyte and electrodes in electrochemical devices such as sensors and transistors. Yarns with specially designed cross-sections, traditionally used in sportswear to wick sweat away from the body and enhance evaporation, was used to transport electrolyte liquids to come in contact with yarn electrodes. The defined area of the junction where the fluidic yarn meets the conductive yarn was shown to increase stability of the measurements and the reproducibility between devices.The results presented in the two publications of this thesis as well as additional results presented in the thesis itself show the promising potential of using textile materials to integrate electronic and electrochemical functionality in our everyday life. This is shown by using basic textile materials and processing techniques to fabricate complex devices for various application areas such as sensors and diagnostics as well as electrical and energy harvesting components.
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| 10. |
- Johannisson, Wilhelm, et al.
(författare)
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A screen-printing method for manufacturing of current collectors for structural batteries
- 2021
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Ingår i: Multifunctional Materials. - : IOP Publishing. - 2399-7532. ; 4:3, s. 035002-
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Tidskriftsartikel (refereegranskat)abstract
- Structural carbon fibre composite batteries are a type of multifunctional batteries that combine the energy storage capability of a battery with the load-carrying ability of a structural material. To extract the current from the structural battery cell, current collectors are needed. However, current collectors are expensive, hard to connect to the electrode material and add mass to the system. Further, attaching the current collector to the carbon fibre electrode must not affect the electrochemical properties negatively or requires time-consuming, manual steps. This paper presents a proof-of-concept method for screen-printing of current collectors for structural carbon fibre composite batteries using silver conductive paste. Current collectors are screen-printed directly on spread carbon fibre tows and a polycarbonate carrier film. Experimental results show that the electrochemical performance of carbon fibre vs lithium metal half-cells with the screen-printed collectors is similar to reference half-cells using metal foil and silver adhered metal-foil collectors. The screen-printed current collectors fulfil the requirements for electrical conductivity, adhesion to the fibres and flexible handling of the fibre electrode. The screen-printing process is highly automatable and allows for cost-efficient upscaling to large scale manufacturing of arbitrary and complex current collector shapes. Hence, the screen-printing process shows a promising route to realization of high performing current collectors in structural batteries and potentially in other types of energy storage solutions.
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| 11. |
- Schellenberger, Steffen, 1981-, et al.
(författare)
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An Outdoor Aging Study to Investigate the Release of Per- And Polyfluoroalkyl Substances (PFAS) from Functional Textiles
- 2022
-
Ingår i: Environmental Science and Technology. - : American Chemical Society. - 0013-936X .- 1520-5851. ; 56, s. 3471-
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Tidskriftsartikel (refereegranskat)abstract
- The emission of per- and polyfluoroalkyl substances (PFAS) from functional textiles was investigated via an outdoor weathering experiment in Sydney, Australia. Polyamide (PA) textile fabrics treated with different water-repellent, side-chain fluorinated polymers (SFPs) were exposed on a rooftop to multiple natural stressors, including direct sunlight, precipitation, wind, and heat for 6-months. After weathering, additional stress was applied to the fabrics through abrasion and washing. Textile characterization using a multiplatform analytical approach revealed loss of both PFAS-containing textile fragments (e.g., microfibers) as well as formation and loss of low molecular weight PFAS, both of which occurred throughout weathering. These changes were accompanied by a loss of color and water repellency of the textile. The potential formation of perfluoroalkyl acids (PFAAs) from mobile residuals was quantified by oxidative conversion of extracts from unweathered textiles. Each SFP-textile finish emitted a distinct PFAA pattern following weathering, and in some cases the concentrations exceeded regulatory limits for textiles. In addition to transformation of residual low molecular weight PFAA-precursors, release of polymeric PFAS from degradation and loss of textile fibers/particles contributed to overall PFAS emissions during weathering. © 2022 The Authors.
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| 12. |
- Dahlbom, Maja, et al.
(författare)
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Sustainable clothing futures - Mapping of textile actors in sorting and recycling of textiles in Europe
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report is as a part of the research project Sustainable clothing futures, and have, through literature and market studies and interviews, identified actors working with sorting and recycling of textiles, with capacities of 560 000 tons and 1.3 million tons per year, respectively.In the interviews, it was clear that an up scale of the capacities is possible, but is depending on several factors, technological development amongst others.
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| 13. |
- Tadesse Abate, Molla
(författare)
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Supercritical CO2 technology in resource-effectiveproduction of functional and smart textiles
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The demand for functional and smart textiles has risen nowadays due to the lifestyle change of human beings. Along with this, the production of functional and smart textiles is consistently increasing. However, the conventional dyeing and finishing methods used to produce the functional textiles have issues such as the requirement of a large amount of fresh-water, energy, and chemicals and the associated wastewater pollution which poses harmful effect to humans, animals, and the environment. Moreover, due to the stringent environmental legislation on effluent release and hence the necessity of wastewater treatment, it has also become an economic problem for the textile industry. Thus, the textile industry has nowadays focused on alternative green technologies and eco-friendly chemical agents to minimize these problems. In this regard, supercritical carbon dioxide (scCO2) dyeing technique is a promising alternative to conventional aqueous-based methods as it avoids the use of water, uses less energy, and fewer chemicals minimizing the waste generation which is important to improve the ecological footprint and reduced production cost. Owing to these important attributes, scCO2 dyeing has been investigated in the last three decades as an environmentally benign process and now it is commercially successful in an industrial scale for dyeing polyester fibres. Thus, employing this technique to textile functionalization can bring additional economic and environmental benefits for the textile dyeing and finishing industry. Nevertheless, only a few attempts have been made so far in using this technology for textile finishing despite having promising potentials.This thesis used scCO2 dyeing technology intending to explore its potential to the production of functional and smart textiles. To fulfil this, firstly, different functional dyes and functional finishing agents of interest suitable for scCO2 media were selected based on literature data and some screening experiments. Based on this, chitosan very low molecular weight and lactate derivatives, curcumin natural dye, and two commercial photochromic dyes based on spirooxazine and naphthopyran dye classes were selected. Secondly, these agents were incorporated into the polyester fabric using scCO2 impregnation technique to impart range functionalities such as antimicrobial, antioxidant, UV protecting and smart UV-sensor fabrics. Moreover, the functional and colour performances of these functional textiles and the effects of the processing variables on the functional/colour properties were explored. Besides, the thesis includes the production of pH sensing functional fabric with a halochromic molecule using photo grafting technique as an alternative resource-efficient method.The results showed that scCO2 is a viable technique for the production of functional polyester fabric in a resource-efficient and eco-friendly way. Dyed polyester fabric with additional functionalities such as antimicrobial, antioxidant, UV protection, and UV sensing properties were realised in a single step. The fabrics developed have demonstrated desirable colour and functional properties without affecting each other confirming compatibility. Moreover, the functional fabrics exhibited the required durability and fastness properties sufficient for various applications. This thesis contributes towards widening the application of supercritical CO2 dyeing technique further and paves a way for sustainable production of functional and smart textiles in a resource-efficient and eco-friendly way. Moreover, the functionalization of cotton fabric with a pH indicator dye using the photo-grafting technique was successful and exhibited good halochromic property towards different pH environments with potential application in several smart textile areas.
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| 14. |
- Xu, Yunsheng, et al.
(författare)
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Methacrylated lignosulfonate as compatibilizer for flax fiber reinforced biocomposites with soybean-derived polyester matrix
- 2020
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Ingår i: Composites Communications. - : Elsevier BV. - 2452-2139.
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Tidskriftsartikel (refereegranskat)abstract
- The poor adhesion between natural fibers and polymer matrix restricts the mechanical performance of natural fiber reinforced composites. Here, lignosulfonate was methacrylated and evaluated as a potential compatibilizer for flax fiber reinforced soybean-derived polyester thermosets. Significant improvement in both tensile and flexural properties of the fiber composites were achieved when the flax fiber mat was treated with methacrylated lignosulfonate solution. In particular, the flexural modulus and flexural strength more than doubled from 2.6 to 6.7 GPa and from 36 MPa to 76.8 MPa, respectively when the fibers were soaked in 5 wt % MLS solution. The SEM analysis revealed improved fiber-matrix interface and lower extent of fiber pull-out in the methacrylated lignosulfonate treated fiber composites, which correlates with the improved mechanical properties.
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| 15. |
- Pal, Rudrajeet, Biträdande Professor, et al.
(författare)
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Demystifying process-level scalability challenges in fashion remanufacturing : An interdependence perspective
- 2021
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Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 286
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to determine how process-level challenges can be solved in order improve scalability of fashion remanufacturing. In order to do so, and prescribe solutions, the paper first conducts a systematic literature review to reveal three categories of process-level challenges that are related to sourcing of input material, process throughput time, and skillset requirement. These categories further guided us in conducting case study with a Swedish charity-owned fashion remanufacturer for exploring how the challenges are addressed and solved in order to achieve process-level scalability. First, our study reveals a systematized approach to determine product-process categories defined by production volume and degree of remanufacturing. Second, by exploring the process-level challenges of six different remanufactured product groups in the case study organization we identify process-level requirements for scalability, and challenges when these are unmet. The findings show that in fashion remanufacturing (particularly disassembly and reassembly), low degree of coupling, high level of formalization of activities and low skill specificity can be ways to attain process-level scalability. Overall, this highlights the need to build lower interdependence between disassembly and reassembly during fashion remanufacturing.
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| 16. |
- Farjana, Sadia, 1983, et al.
(författare)
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Low Loss Gap Waveguide Transmission line and Transitions at 220-320 GHz Using Dry Film Micromachining
- 2021
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Ingår i: IEEE Transactions on Components, Packaging and Manufacturing Technology. - 2156-3985 .- 2156-3950. ; 11:11, s. 2012-2021
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel microfabrication technique to manufacture gap waveguide components operating at sub-millimeter wave (sub-mmWave) frequency range. The conventional metal waveguide component manufacturing has a low resolution and low throughput and is not suitable for applications above 100 GHz. The micromachining techniques have matured and applied in various applications. Several micromachining techniques have been developed to address the specification requirements of different fields. Conventional micromachining techniques suffer from fabrication issues such as non-vertical sidewall, non-uniform surface, and time-consuming fabrication process. The proposed dry film photoresist offers significant amount of benefits such as fewer processing steps, reduced production cost, shorter prototyping time over existing micromachine techniques. To validate the proposed fabrication method, SUEX dry film photoresist is used to demonstrate three gap waveguide transmission lines. Different transitions from rectangular waveguide (RW) to gap waveguide (GW) have also been designed to characterize the newly fabricated gap waveguide components with a standard measurement setup. All the designed and fabricated device operates from 220 GHz to 320 GHz. The fabricated devices showed a good agreement with the simulation result over this frequency band and the measured average insertion losses were in the order of 0.048 dB/mm and 0.075 dB/mm for groove gap waveguide and ridge gap waveguide respectively. Thus, dry film photoresist provides fabrication precision of the structures and consequently opens the path for low-cost fabrication of high-frequency waveguide components.
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| 17. |
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| 18. |
- Ghai, Viney, 1989, et al.
(författare)
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Orientation of graphene nano sheets in magnetic fields
- 2024
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Ingår i: Progress in Materials Science. - 0079-6425. ; 143
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Forskningsöversikt (refereegranskat)abstract
- Aligning anisotropic nanoparticles using external fields is one of the major obstacles to unlocking their enormous potential for novel applications. The most famous such example is graphene, a 2D family of nanomaterials that has received enormous attention since its discovery. Using graphene to enhance mechanical, thermal, electric or gas barrier properties, imparting antibacterial properties etc., relies to a great extent on the ability to control their orientation inside a matrix material, i.e., polymers. Here we summarize the latest advances on graphene orientation using magnetic fields. The review covers the underlying physics for graphene interaction with magnetic fields, theoretical continuum mechanics framework for inducing orientation, typical magnetic field orientation setups, and a summary of latest advances in their use to enhance the performance of materials. Current trends, limitations of current alignment techniques are highlighted and major challenges in the field are identified.
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| 19. |
- da Costa, Marcus Vinicius Tavares, et al.
(författare)
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Prediction of loss of barrier properties in cracked thin coatings on polymer substrates subjected to tensile strain
- 2021
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 426
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Tidskriftsartikel (refereegranskat)abstract
- Thin brittle coatings on polymer films are a potentially useful material combination for food packaging applications. The brittle coatings inevitably risk cracking when the package is converted. This strain-induced cracking leads to a loss of the key barrier properties. In design of packaging materials, it would be useful to predict the loss of the oxygen transmission rate (OTR) as a function of the applied tensile strain, which are linked by the crack opening and crack spacing in the coating. Previous works have presented a model that predicts the effect of strain on the OTR in the presence of cracks in the coating. This work uses an improved numerical model based on finite element method (FEM) to predict the oxygen permeability more accurately, especially for thin coatings with high crack densities. The numerical predictions show reasonable correspondence with experimental results for SiOx coatings. These results as well as predictions for previously tested metal-oxide coated polymer films show a significant increase in OTR at crack onset, which suggests that efforts should be made to make the coatings more ductile with higher crack onset strains if the barrier performance should be maintained in converted packages. The quantitative link from deformation over the damage state to barrier properties indicate that mechanics could provide a tool to aid the design of improved food packages with retained barrier capacity.
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| 20. |
- Samanta, Archana, 1990, et al.
(författare)
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Wet spinning of strong cellulosic fibres with incorporation of phase change material capsules stabilized by cellulose nanocrystals
- 2023
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Ingår i: Carbohydrate Polymers. - : Elsevier Ltd. - 0144-8617 .- 1879-1344. ; 312
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Tidskriftsartikel (refereegranskat)abstract
- Incorporating a phase change material (PCM) into fibres allows the fabrication of smart textiles with thermo-regulating properties. Previously, such fibres have been made from thermoplastic polymers, usually petroleum-based and non-biodegradable, or from regenerated cellulose, such as viscose. Herein, strong fibres are developed from aqueous dispersions of nano-cellulose and dispersed microspheres with phase changing characteristics using a wet spinning technique employing a pH shift approach. Good distribution of the microspheres and proper compatibility with the cellulosic matrix was demonstrated by formulating the wax as a Pickering emulsion using cellulose nanocrystals (CNC) as stabilizing particles. The wax was subsequently incorporated into a dispersion of cellulose nanofibrils, the latter being responsible for the mechanical strength of the spun fibres. It was possible to produce fibres highly loaded with the microspheres (40 wt%) with a tenacity of 13 cN tex−1 (135 MPa). The fibres possessed good thermo-regulating features by absorbing and releasing heat without undergoing structural changes, while maintaining the PCM domain sizes intact. Finally, good washing fastness and PCM leak resistance were demonstrated, making the fibres suitable for thermo-regulative applications. Continuous fabrication of bio-based fibres with entrapped PCMs may find applications as reinforcements in composites or hybrid filaments. © 2023 The Authors
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| 21. |
- Depalo, Francesco, et al.
(författare)
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Effects of dynamic axial stiffness of elastic moorings for a wave energy converter
- 2022
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Ingår i: Ocean Engineering. - : Elsevier BV. - 0029-8018. ; 251
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Tidskriftsartikel (refereegranskat)abstract
- This work studies the effects of the dynamic axial stiffness of elastic moorings on the dynamic behaviour of a point absorber wave energy converter. Following two mooring analysis procedures, coupled dynamic analysis of a taut-moored WEC with three legs is performed using the FEM program DeepC in three irregular wave conditions. Two synthetic fibre rope materials are investigated, i.e. a normally stiff polyester and a wire-lay 3-strand nylon rope. The results of WEC motions and mooring tensions obtained from a quasi-static stiffness model and the dynamic stiffness model are compared and discussed. The former analysis applies the non-linear stiffness working curves of the ropes in the simulations, while the latter utilizes the dynamic stiffness expression with an iterative process following a practical mooring analysis procedure. For the nylon rope, the influence of the load amplitude on the dynamic stiffness and the WEC response is presented and analysed. It was found that the quasi-static stiffness model tends to underestimate the maximum mooring tensions, leading to 30%–40% lower results compared to the one accounting for the dynamic stiffness effects. For the studied WEC system, the nylon rope shows advantages over polyester, because of the lower mooring tensions and higher WEC motions.
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| 22. |
- Hafid, Abdelakram, et al.
(författare)
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Sensorized T-Shirt with Intarsia-Knitted Conductive Textile Integrated Interconnections: Performance Assessment of Cardiac Measurements during Daily Living Activities
- 2023
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Ingår i: Sensors. - 1424-8220. ; 23:22
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Tidskriftsartikel (refereegranskat)abstract
- The development of smart wearable solutions for monitoring daily life health status is increasingly popular, with chest straps and wristbands being predominant. This study introduces a novel sensorized T-shirt design with textile electrodes connected via a knitting technique to a Movesense device. We aimed to investigate the impact of stationary and movement actions on electrocardiography (ECG) and heart rate (HR) measurements using our sensorized T-shirt. Various activities of daily living (ADLs), including sitting, standing, walking, and mopping, were evaluated by comparing our T-shirt with a commercial chest strap. Our findings demonstrate measurement equivalence across ADLs, regardless of the sensing approach. By comparing ECG and HR measurements, we gained valuable insights into the influence of physical activity on sensorized T-shirt development for monitoring. Notably, the ECG signals exhibited remarkable similarity between our sensorized T-shirt and the chest strap, with closely aligned HR distributions during both stationary and movement actions. The average mean absolute percentage error was below 3%, affirming the agreement between the two solutions. These findings underscore the robustness and accuracy of our sensorized T-shirt in monitoring ECG and HR during diverse ADLs, emphasizing the significance of considering physical activity in cardiovascular monitoring research and the development of personal health applications.
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| 23. |
- Chen, Jiajia, et al.
(författare)
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Characterization of Longitudinal Thermal Conductivity of Graphene Film
- 2021
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Ingår i: 2021 22nd International Conference on Electronic Packaging Technology, ICEPT 2021.
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Konferensbidrag (refereegranskat)abstract
- The chase of high performance by chip manufacturers has greatly increased the power consumption of integrated circuits, which brings great challenges to the heat dissipation of electronics systems. It has also slowed down following up of the Moore's Law, and it is expected to hit the wall soon [1]. Graphene film with high in-plane thermal conductivity is one of the key materials to make it possible for electronics industry to continue to follow the Moore's Law. However, there are few studies focusing on the longitudinal thermal conductivity of graphene films. The purpose of this study is to investigate the longitudinal thermal conductivity of graphene films according to ASTM D5470 [2]. The results show that the longitudinal thermal conductivity of the pressed graphene film is greater than that of the unpressurized graphene film. The longitudinal thermal conductivity is 10.6 W/m· K for the unpressurized graphene film and 20.6 W/m· K for the pressed graphene film.
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| 24. |
- Mehraeen, Shayan, et al.
(författare)
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Effect of Core Yarn on Linear Actuation of Electroactive Polymer Coated Yarn Actuators
- 2023
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Ingår i: Advanced Materials Technologies. - : John Wiley & Sons. - 2365-709X.
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Tidskriftsartikel (refereegranskat)abstract
- Smart textiles combine the features of conventional textiles with promising properties of smart materials such as electromechanically active polymers, resulting in textile actuators. Textile actuators comprise of individual yarn actuators, so understanding their electro-chemo-mechanical behavior is of great importance. Herein, this study investigates the effect of inherent structural and mechanical properties of commercial yarns, that form the core of the yarn actuators, on the linear actuation of the conducting-polymer-based yarn actuators. Commercial yarns were coated with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) to make them conductive. Then polypyrrole (PPy) that provides the electromechanical actuation is electropolymerized on the yarn surface under controlled conditions. The linear actuation of the yarn actuators is investigated in aqueous electrolyte under isotonic and isometric conditions. The yarn actuators generated an isotonic strain up to 0.99% and isometric force of 95 mN. The isometric strain achieved in this work is more than tenfold and threefold greater than the previously reported yarn actuators. The isometric actuation force shows an increase of nearly 11-fold over our previous results. Finally, a qualitative mechanical model is introduced to describe the actuation behavior of yarn actuators. The strain and force created by the yarn actuators make them promising candidates for wearable actuator technologies. © 2023 The Authors. Advanced Materials Technologies published by Wiley-VCH GmbH.
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| 25. |
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