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Bengt Hagström

Other affiliations: Research Institutes of Sweden
Bio: Bengt Hagström is an academic researcher from Chalmers University of Technology. The author has contributed to research in topics: Melt spinning & Electrospinning. The author has an hindex of 15, co-authored 39 publications receiving 1036 citations. Previous affiliations of Bengt Hagström include Research Institutes of Sweden.

Papers
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Journal ArticleDOI
TL;DR: In this article, the influence of humidity and temperature on the formation and the properties of nanofibres are studied using cellulose acetate (CA) and poly(vinylpyrrolidone) (PVP) as target materials.
Abstract: Electrospinning is a process that generates nanofibres. Temperature and humidity affect this process. In this article the influence of humidity and temperature on the formation and the properties of nanofibres are studied using cellulose acetate (CA) and poly(vinylpyrrolidone) (PVP) as target materials. The experiments indicate that two major parameters are dependent of temperature and have their influence on the average fibre diameter. A first parameter is the solvent evaporation rate that increases with increasing temperature. The second parameter is the viscosity of the polymer solution that decreases with increasing temperature. The trend in variation of the average nanofibre diameter as a function of humidity is different for CA and PVP, which can be explained by variations in chemical and molecular interaction and its influence on the solvent evaporation rate. As the humidity increases, the average fibre diameter of the CA nanofibres increases, whilst for PVP the average diameter decreases. The average diameter of nanofibres made by electrospinning change significantly through variation of temperature and humidity.

428 citations

Journal ArticleDOI
22 Mar 2018
TL;DR: In this article, the authors use a weaving loom to realize textile bands with yarns of melt-spun piezoelectric microfibres, that consist of a conducting core surrounded by β-phase poly(vinylidene fluoride) (PVDF), in the warp direction.
Abstract: Recent advances in ubiquitous low-power electronics call for the development of light-weight and flexible energy sources. The textile format is highly attractive for unobtrusive harvesting of energy from e.g., biomechanical movements. Here, we report the manufacture and characterisation of fully textile piezoelectric generators that can operate under wet conditions. We use a weaving loom to realise textile bands with yarns of melt-spun piezoelectric microfibres, that consist of a conducting core surrounded by β-phase poly(vinylidene fluoride) (PVDF), in the warp direction. The core-sheath constitution of the piezoelectric microfibres results in a—for electronic textiles—unique architecture. The inner electrode is fully shielded from the outer electrode (made up of conducting yarns that are integrated in the weft direction) which prevents shorting under wet conditions. As a result, and in contrast to other energy harvesting textiles, we are able to demonstrate piezoelectric fabrics that do not only continue to function when in contact with water, but show enhanced performance. The piezoelectric bands generate an output of several volts at strains below one percent. We show that integration into the shoulder strap of a laptop case permits the continuous generation of four microwatts of power during a brisk walk. This promising performance, combined with the fact that our solution uses scalable materials and well-established industrial manufacturing methods, opens up the possibility to develop wearable electronics that are powered by piezoelectric textiles.

120 citations

Journal ArticleDOI
TL;DR: In this article, 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 car...
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 car ...

111 citations

Journal ArticleDOI
TL;DR: In this article, the effect of melt spinning and cold drawing parameters on the formation of β-phase crystallinity in polyvinylidene fluoride (PVDF) fibres, and ways of increasing such crystallinity, were studied.
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.

61 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the main characteristics of the electroactive phases of polyvinylidene fluoride and copolymers are summarized, and some interesting potential applications and processing challenges are discussed.

2,242 citations

Journal ArticleDOI
TL;DR: In this paper, the authors provide an overview of the electrospinning (applied electric field, distance between the needle and collector and flow rate, needle diameter), solution (polymer concentration, viscosity, solvent and solution conductivity) and environmental (relativity humidity and temperature) parameters that affect the nanofibers fabrication.

1,071 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed an extension of electrospinning towards fiber formation based not only on polymers of synthetic, biological nature, but also on metals, metal oxides, ceramics, organic/organic, organic-inorganic as well as inorganic/inorganic composite systems.

763 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a review on the preparation and application of electrospun nanofiber membranes as the barrier layer for water treatment, with emphasis on the reinforcement and post-treatment of electro-spun polymer membranes.

742 citations

Journal ArticleDOI
TL;DR: A critical review is presented on the current state of the arts of wearable fiber/fabric-based piezoelectric nanogenerators and triboelectrics with respect to basic classifications, material selections, fabrication techniques, structural designs, and working principles, as well as potential applications.
Abstract: Integration of advanced nanogenerator technology with conventional textile processes fosters the emergence of textile-based nanogenerators (NGs), which will inevitably promote the rapid development and widespread applications of next-generation wearable electronics and multifaceted artificial intelligence systems. NGs endow smart textiles with mechanical energy harvesting and multifunctional self-powered sensing capabilities, while textiles provide a versatile flexible design carrier and extensive wearable application platform for their development. However, due to the lack of an effective interactive platform and communication channel between researchers specializing in NGs and those good at textiles, it is rather difficult to achieve fiber/fabric-based NGs with both excellent electrical output properties and outstanding textile-related performances. To this end, a critical review is presented on the current state of the arts of wearable fiber/fabric-based piezoelectric nanogenerators and triboelectric nanogenerators with respect to basic classifications, material selections, fabrication techniques, structural designs, and working principles, as well as potential applications. Furthermore, the potential difficulties and tough challenges that can impede their large-scale commercial applications are summarized and discussed. It is hoped that this review will not only deepen the ties between smart textiles and wearable NGs, but also push forward further research and applications of future wearable fiber/fabric-based NGs.

729 citations