| 1. |
- Darabi, Sozan, 1994, et al.
(författare)
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Green Conducting Cellulose Yarns for Machine-Sewn Electronic Textiles
- 2020
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 12:50, s. 56403-56412
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Tidskriftsartikel (refereegranskat)abstract
- The emergence of "green"electronics is a response to the pressing global situation where conventional electronics contribute to resource depletion and a global build-up of waste. For wearable applications, green electronic textile (e-textile) materials present an opportunity to unobtrusively incorporate sensing, energy harvesting, and other functionality into the clothes we wear. Here, we demonstrate electrically conducting wood-based yarns produced by a roll-to-roll coating process with an ink based on the biocompatible polymer:polyelectrolyte complex poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The developed e-textile yarns display a, for cellulose yarns, record-high bulk conductivity of 36 Scm-1, which could be further increased to 181 Scm-1 by adding silver nanowires. The PEDOT:PSS-coated yarn could be machine washed at least five times without loss in conductivity. We demonstrate the electrochemical functionality of the yarn through incorporation into organic electrochemical transistors (OECTs). Moreover, by using a household sewing machine, we have manufactured an out-of-plane thermoelectric textile device, which can produce 0.2 μW at a temperature gradient of 37 K.
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| 2. |
- Lund, Anja, et al.
(författare)
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Enhancement of beta phase crystals formation with the use of nanofillers in PVDF films and fibres
- 2011
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Ingår i: Composites Science And Technology. - : Elsevier Ltd.. - 0266-3538 .- 1879-1050. ; 71:2, s. 222-229
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Tidskriftsartikel (refereegranskat)abstract
- Nanoclay and carbon nanotubes (CNT) have been in focus recently as means of enhancing beta phase crystals formation in poly(vinylidene fluoride)(PVDF). Dominantly, the so-far work has been carried out on films/ thin sheets filled with nanoclay. It has been found, mainly from combined XRD and DSC data, that nanoclay influences the PVDF structure, and particularly the beta phase crystals formation is enhanced. Results published by various groups are in fairly good agreement. There are no results for nanoclay filled melt-spun PVDF fibres. The influence of CNT on PVDF structure has been less studied. XRD data indicating an enhancing role of multi-wall carbon nanotubes (MWNT) on beta phase crystals formation in solution compounded PVDF films are available. Published results for MWNT/PVDF films are not in good agreement. The only study into single-wall carbon nanotube (SWNT)/PVDF has been made on electrospun nanofibres. We explore above findings towards melt-spun nanofilled PVDF fibres. We present new results obtained by us for melt-spun PVDF fibres containing non-functionalized and amino-functionalized double-wall carbon nanotubes (DWNT). The key finding is that amino-DWNT can influence the beta to alpha polymorphic balance.
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| 3. |
- Lund, Anja, et al.
(författare)
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Melt spinning of beta-phase poly(vinylidene fluoride) yarns with and without a conductive core
- 2011
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Ingår i: Journal of Applied Polymer Science. - : Wiley Periodicals, Inc.. - 0021-8995 .- 1097-4628. ; 120:2, s. 1080-1089
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Tidskriftsartikel (refereegranskat)abstract
- When poly(vinylidene fluoride) (PVDF) is to be used as a piezoelectric material, the processing must include the formation of polar β-phase crystallites, as well as the application of electrically conducting charge collectors, that is, electrodes. In this article, results from the melt spinning of PVDF yarns and a novel bicomponent PVDF-yarn with a conductive carbon black/polypropylene (CB/PP) core are presented. Melt spinning has been done under conditions typical for industrial large-scale fiber production. The effects on the resulting crystalline structure of varying the spinning velocity, draw rate, and draw temperature are discussed. The results show that, for maximum α-to-β phase transformation, cold drawing should take place at a temperature between 70 and 90°C, and both the draw ratio and the draw rate should be as high as possible. It was observed that the cold drawing necessary to form β-phase crystallinity simultaneously leads to a decrease in the core conductivity of the bicomponent yarns. In this work, the melt spinning of bicomponent fibers with high-β-phase PVDF in the sheath and a CB/PP core was successfully accomplished. The core material remained electrically conductive, paving the way for the use of a CB-polymer compound as inner electrode in the melt spinning of piezoelectric bicomponent fibers.
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| 4. |
- Lund, Anja, et al.
(författare)
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Melt spinning of poly(vinylidene fluoride) fibers and the influence of spinning parameters on beta-phase crystallinity
- 2010
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Ingår i: Journal of Applied Polymer Science. - : Wiley Periodicals, Inc. - 0021-8995 .- 1097-4628. ; 116:5, s. 2685-2693
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Tidskriftsartikel (refereegranskat)abstract
- The effect of melt spinning and cold drawing parameters on the formation of β-phase crystallinity in Poly(Vinylidene Fluoride) (PVDF) fibres, and ways of increasing such crystallinity, were studied. Fibres were melt-spun using four different melt draw ratios, and subsequently cold-drawn at different draw ratios. The maximum draw ratio in cold drawing was dependent on the draw ratio used in the melt spinning. The crystalline structure of the fibres was studied mainly by DSC and XRD. Results showed that the degree of crystallinity in the fibres was determined by the melt draw ratio, and that before cold drawing the crystalline structure of the fibres was predominantly in the α form. By cold drawing, α-phase crystallites could be transformed into the β-phase. It was established that, at certain conditions of melt spinning and cold drawing, PVDF fibres containing up to 80% of mainly β form crystallinity can be prepared. It is further proposed that fibres spun at a sufficiently high melt draw ratio consist to a large extent of extended-chain crystals, and this greatly affects the melting point of the PVDF. Thus DSC melting point data were shown to be insufficient to determine the crystalline phase of PVDF.
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| 5. |
- Lund, Anja
(författare)
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Melt spun piezoelectric textile fibres : an experimental study
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Melt Spun Piezoelectric Textile Fibres - an Experimental Study ANJA LUND Department of Materials and Manufacturing Technology Chalmers University of Technology ABSTRACT The manufacturing and characterisation of piezoelectric textile fibres are described in this thesis. A piezoelectric material is one that generates an electric voltage when deformed, a property which exists in a number of materials. The polymer with the strongest known piezoelectric effect today is poly(vinylidene fluoride) (PVDF), however it must be processed under certain conditions to become piezoelectric. This study shows that piezoelectric bicomponent PVDF-based fibres can be produced by melt spinning, which is a common and relatively simple fibre spinning method. The melt spinning process must include cold drawing, as this introduces a polar crystalline structure in the polymer. The fibres must also be electroded, which is done by producing bicomponent fibres with a core-and-sheath structure. The core is electrically conductive and constitutes an inner electrode consisting of a carbon black/polymer compound, whereas the sheath is PVDF and constitutes the piezoelectric component. Being sensitive to both deformation and temperature changes, these fibres are anticipated to be useful in a number of sensor applications. The flexibility and small size of the fibres makes it possible to include them as miniature-sensors in structures or garment without affecting the shape or comfort.
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| 6. |
- Lund, Anja, et al.
(författare)
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Piezoelectric polymeric bicomponent fibers produced by melt spinning
- 2012
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Ingår i: Journal of Applied Polymer Science. - : Wiley Periodicals, Inc.. - 0021-8995 .- 1097-4628. ; 126:2, s. 490-500
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Tidskriftsartikel (refereegranskat)abstract
- Melt spinning of a novel piezoelectric bicomponent fiber, with poly(vinylidene fluoride) as the electroactive sheath component, has been demonstrated. An electrically conductive compound of carbon black (CB) and high density polyethylene was used as core material, working as an inner electrode. A force sensor consisting of a number of fibers embedded in a soft CB/polyolefin elastomer matrix was manufactured for characterization. The fibers showed a clear piezoelectric effect, with a voltage output (peak-to-peak) of up to 40 mV under lateral compression. This continuous all-polymer piezoelectric fiber introduces new possibilities toward minimal single fiber sensors as well as large area sensors produced in standard industrial weaving machines.
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| 7. |
- Nilsson, Erik, 1976, et al.
(författare)
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Poling and characterization of piezoelectric polymer fibers for use in textile sensors
- 2013
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Ingår i: Sensors and Actuators A-Physical. - : Elsevier S.A.. - 0924-4247 .- 1873-3069. ; 201, s. 477-486
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Tidskriftsartikel (refereegranskat)abstract
- This study reports on the poling and characteristics of a melt-spun piezoelectric bicomponent fiber with poly(vinylidene fluoride) (PVDF) as its sheath component and a conductive composite with carbon black (CB) and high density polyethylene (HDPE) as its core component. The influence of poling conditions on the piezoelectric properties of the fibers has been investigated. The poling parameters temperature, time and poling voltage have been varied and the piezoelectric effect of both contact- and corona-poled yarns have been evaluated. The results show that a high piezoelectric effect is achieved when the poling voltage is high as possible and the poling temperature is between 60°C and 120°C. It was also shown that permanent polarization is achieved in a time as short as 2 second in corona-poled fibers. A yarn exposed to a sinusoidal axial tension of 0.07% strain (the corresponding force amplitude was 0.05 N) shows an intrinsic voltage output of 4 V. The mean power from a 25 mm length of yarn is estimated to be 15nW. To demonstrate the fibers sensor properties, they are woven into a textile fabric from which a force sensor is manufactured and used to detect the heartbeat of a human.
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| 8. |
- Satyanarayana, K. C., et al.
(författare)
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Analysis of the torsion angle distribution of poly(vinylidene fluoride) in the melt
- 2012
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Ingår i: Polymer. - : Elsevier BV. - 0032-3861 .- 1873-2291. ; 53:5, s. 1109-1114
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of the torsion angle distribution of poly(vinylidene fluoride) (PVDF) structures at temperatures above its melting point is addressed by combining first principles methods, atomistic simulations and laboratory experiments. Amorphous, alpha- and beta-conformations of PVDF structures have been considered. The results from the atomistic simulations as well as the experiments show that there is a larger probability of the PVDF torsions to be near +/- 180 degrees at temperatures above the melting point, which is associated more with the beta-conformation than the alpha-conformation.
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| 9. |
- Åkerfeldt, Maria, 1982, et al.
(författare)
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Textile sensing glove with piezoelectric PVDF fibers and printed electrodes of PEDOT:PSS
- 2015
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Ingår i: Textile Research Journal. - : SAGE Publications. - 0040-5175 .- 1746-7748. ; 85:17, s. 1789-1799
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Tidskriftsartikel (refereegranskat)abstract
- The development of an entirely polymer-based motion sensing glove with possible applications, for example, in physical rehabilitation is described. The importance of comfort for the wearer and the possibility to clean the glove in normal laundering processes were important aspects in the development. The glove is all textile and manufactured using materials and methods suitable for standard textile industry processes. For the first time, melt-spun piezoelectric poly(vinylidene fluoride) (PVDF) fibers with conductive cores were machine embroidered onto a textile glove to function as a sensor element. Electrodes and electrical interconnections were constituted by a screen printed conductive poly(3,4- ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) formulation. The screen printing of the interconnections was shown to be a reliable method for reproducible material deposition, resulting in an average surface resistivity value of 57/square. A repeated strain of 10% only influenced the resistance of the interconnections initially and to a very limited extent. The influence of washing on the electrical resistance of the printed interconnections was also studied; after 15 wash cycles the average surface resistivity was still below 500/square, which was deemed sufficient for the polymeric sensor system to remain functional during long-term use. Sensor data from the glove was also successfully used as input to a microcontroller running a robot gripper, in order to demonstrate its potential applications.
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