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  • 1.
    Aitomäki, Yvonne
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, SICOMP.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Långström, R.
    RISE - Research Institutes of Sweden, Materials and Production, SICOMP.
    Fernberg, P.
    RISE - Research Institutes of Sweden, Materials and Production, SICOMP.
    Novel reactive bicomponent fibres: Material in composite manufacturing2012In: Journal of Nanostructured Polymers and Nanocomposites, ISSN 17904439, Vol. 8, no 1, p. 11-majArticle in journal (Refereed)
    Abstract [en]

    The hypotheses that reactive uncured, thermoset bicomponent fibres can be prepared and mixed with reinforcing fibres and ultimately used in preparation of a composite was tested and is described. It is thought that such fibres have the two potential advantages: (1) to enable manufacturing with particle doped resins e.g. nanocomposites which add functionality to composites and (2) increased efficiency of structural composite manufacturing by increasing the level of automation. The structure of the thermoset fibres comprises of a sheath of thermoplastic and a core of uncured thermoset resin. Once manufactured, the fibres were wound with a reinforced fibre onto a plate, consolidated and cured. The resulting composite was examined and compared to other composites made with the same manufacturing method from commercially available materials. The results show that a laminate can be produced using these reactive bicomponent fibres. The resin system successfully impregnates the reinforcing carbon fibres and that the thermoplastic separates from the epoxy resin system during consolidation. In comparison to reference material, the bicomponent laminate shows promising characteristics. However, the processes developed are currently on a lab-scale and considerable improvement of various bicomponent fibre properties, such as the strength, are required before the technology can be used on a larger scale.

  • 2.
    Aitomäki, Yvonne
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, SICOMP.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Långström, Runar
    RISE - Research Institutes of Sweden, Materials and Production, SICOMP.
    Fernberg, Patrik
    RISE - Research Institutes of Sweden, Materials and Production, SICOMP.
    Novel reactive bicomponent fibres: Material in composite manufacturing2012In: Journal of Nanostructured Polymers and Nanocomposites, ISSN 17904439, Vol. 8, no 1, p. s.5-11Article in journal (Refereed)
    Abstract [en]

    The hypotheses that reactive uncured, thermoset bicomponent fibres can be prepared and mixed with reinforcing fibres and ultimately used in preparation of a composite was tested and is described. It is thought that such fibres have the two potential advantages: (1) to enable manufacturing with particle doped resins e.g. nanocomposites which add functionality to composites and (2) increased efficiency of structural composite manufacturing by increasing the level of automation. The structure of the thermoset fibres comprises of a sheath of thermoplastic and a core of uncured thermoset resin. Once manufactured, the fibres were wound with a reinforced fibre onto a plate, consolidated and cured. The resulting composite was examined and compared to other composites made with the same manufacturing method from commercially available materials. The results show that a laminate can be produced using these reactive bicomponent fibres. The resin system successfully impregnates the reinforcing carbon fibres and that the thermoplastic separates from the epoxy resin system during consolidation. In comparison to reference material, the bicomponent laminate shows promising characteristics. However, the processes developed are currently on a lab-scale and considerable improvement of various bicomponent fibre properties, such as the strength, are required before the technology can be used on a larger scale.

  • 3.
    Alt Murphy, Margit
    et al.
    University of Gothenburg, Sweden.
    Bergquist, Filip
    University of Gothenburg, Sweden.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Hernández, Niina
    University of Borås, Sweden.
    Johansson, Dongni
    University of Gothenburg, Sweden.
    Ohlsson, Fredrik
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Sandsjö, Leif
    University of Borås, Sweden; Chalmers University of Technology, Sweden.
    Wipenmyr, Jan
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Malmgren, Kristina
    University of Gothenburg, Sweden; Sahlgrenska University Hospital, Sweden.
    An upper body garment with integrated sensors for people with neurological disorders – early development and evaluation2019In: BMC Biomedical Engineering, Vol. 1, article id 3Article in journal (Refereed)
    Abstract [en]

    Background

    In neurology and rehabilitation the primary interest for using wearables is to supplement traditional patient assessment and monitoring in hospital settings with continuous data collection at home and in community settings. The aim of this project was to develop a novel wearable garment with integrated sensors designed for continuous monitoring of physiological and movement related variables to evaluate progression, tailor treatments and improve diagnosis in epilepsy, Parkinson’s disease and stroke.

    Methods

    In this paper the early development and evaluation of a prototype designed to monitor movements and heart rate is described. An iterative development process and evaluation of an upper body garment with integrated sensors included: identification of user needs, specification of technical and garment requirements, garment development and production as well as evaluation of garment design, functionality and usability. The project is a multidisciplinary collaboration with experts from medical, engineering, textile, and material science within the wearITmed consortium. The work was organized in regular meetings, task groups and hands-on workshops. User needs were identified using results from a mixed-methods systematic review, a focus group study and expert groups. Usability was evaluated in 19 individuals (13 controls, 6 patients with Parkinson’s disease) using semi-structured interviews and qualitative content analysis.

    Results

    The garment was well accepted by the users regarding design and comfort, although the users were cautious about the technology and suggested improvements. All electronic components passed a washability test. The most robust data was obtained from accelerometer and gyroscope sensors while the electrodes for heart rate registration were sensitive to motion artefacts. The algorithm development within the wearITmed consortium has shown promising results.

    Conclusions

    The prototype was accepted by the users. Technical improvements are needed, but preliminary data indicate that the garment has potential to be used as a tool for diagnosis and treatment selection and could provide added value for monitoring seizures in epilepsy, fluctuations in PD and activity levels in stroke. Future work aims to improve the prototype further, develop algorithms, and evaluate the functionality and usability in targeted patient groups. The potential of incorporating blood pressure and heart-rate variability monitoring will also be explored.

  • 4.
    De Vrieze, S.
    et al.
    Ghent University.
    Van Camp, T.
    Ghent University.
    Nelvig, Anna
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Westbroek, P.
    Ghent University.
    De Clerck, K.
    Ghent University.
    The effect of temperature and humidity on electrospinning2009In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 44, no 5, p. 1357-1362Article in journal (Refereed)
    Abstract [en]

    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. © 2008 Springer Science+Business Media, LLC.

  • 5.
    Færevik, H.
    et al.
    SINTEF.
    Gersching, D.
    TITK.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Novel temperature regulating fibers and garments2013In: Chemical Fibers International, ISSN 14343584, Vol. 63, no 2, p. 89-90Article in journal (Refereed)
    Abstract [en]

    The objective of the EU-funded research project Noterefiga was to develop novel temperature regulating fibers and innovative textile products for thermal management and improved comfort. The temperature regulating effect was achieved by novel methods of incorporating large amounts of phase changing materials (PCM) in textile fibers. The PCM melted and absorbed the heat from the body in the form of latent heat when the body temperature increased. The PCM crystallized and the stored heat was released again when the temperature dropped. It was assumed that clothes with built-in thermo-regulating properties would provide maintained thermal comfort in difficult thermal environments and physical activity situations. The thermophysiological effect of the developed PCM garments were evaluated on 24 human subjects in controlled environmental conditions under the Noterefiga project.

  • 6.
    Guo, Zengwei
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Preparation of polypropylene/nanoclay composite fibers2013In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 53, no 10, p. 2035-2044Article in journal (Refereed)
    Abstract [en]

    Melt spinning of nanoclay (NA)/polypropylene (PP) composites into textile fibers is studied. The synthetic NA Perkalite F100 is prone to be exfoliated in PP matrix. With the help of a maleic anhydride-grafted low-molecular-weight PP as compatibilizer (Epolene E43), a highly exfoliated PP/NA composite was successfully prepared. However, the prepared PP/NA composite shows a poor spinnability because of the phase separation between Epolene E43 and PP matrix. The combination of two different groups of compatibilizers, which are Polybond 1001 (acrylic acid-grafted PP) for the dispersion of NA and Epolene G3216 (maleic anhydride-grafted PP-based copolymer) for the exfoliation of NA, can solve this problem. The PP/NA composite prepared by these two compatibilizers can be smoothly spun into fiber at the NA concentration below 1.9 wt%, which is found to be the percolation concentration of formation of NA network structure in PP matrix. © 2013 Society of Plastics Engineers.

  • 7.
    Guo, Zengwei
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Nilsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Rigdahl, M.
    Chalmers University of Technology.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Melt spinning of PVDF fibers with enhanced β phase structure2013In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 130, no 4, p. 2603-2609Article in journal (Refereed)
    Abstract [en]

    Polyvinylidene fluoride (PVDF) fibers with a high amount of β phase crystal structure were prepared by melt spinning. With this technique, the cold drawing process is critical and efficient when aiming for a high amount of β phase. During the cold drawing process, more than 80% of the originally formed α phase crystal structure was converted into the β phase structure. In addition, the incorporation of 0.01 wt % of amino-modified double wall carbon nanotube (NH2-DWCNT) could further enhance the β phase content in the PVDF fibers. FTIR and DSC studies showed that the addition of NH2-DWCNT to PVDF fibers could increase both the total crystallinity and β phase fraction in PVDF. The addition of nanoclay was found to be less efficient in this respect. © 2013 Wiley Periodicals, Inc.

  • 8.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Industrial scale production of nanofibers from polymer solutions2012Conference paper (Other academic)
  • 9.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Temperature regulating textile fibers containing large amounts of phase change material2010In: Chemical Fibers International, 2010, Vol. 60, no 4, p. 221-223Conference paper (Refereed)
    Abstract [en]

    Integration of phase change materials (PCM's) in textile fibers is a means to achieve thermo-regulating properties. When the body temperature goes up, the PCM melts and absorbs the heat from the body in the form of latent heat (cooling effect). When the temperature drops, the PCM crystallizes and the stored heat is released again (warming effect). PCM's can be integrated into textile fibers by means of melt spun bi-component fibers with a sheath/core structure. In this way PCM is trapped inside the fibers. Bi-component fibers with PA6 and PET sheaths were in this way successfully produced. Fibers containing up to about 40% PCM were produced showing heat of fusions up to about 80 J/g and tenacities above 15 cN/tex. The loss of PCM during use and repeated washing cycles was shown to be low.

  • 10.
    Hagström, Bengt
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Rössler, Joraine
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Controlling Strength and Conductivity of Functional Wet-Spun Cellulose Fibers through Different Types of Carbon Black2015Conference paper (Other academic)
  • 11.
    Hagström, Bengt
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Rössler, Joraine
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Electrical Functionalization of Wet-Spun Cellulose Fibers through Different Grades of Carbon Black2015Conference paper (Other academic)
  • 12.
    Hagström, Bengt
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Rössler, Joraine
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Influence of Differently Structured Carbon Black on Electrical and Mechanical Properties of Wet-Spun Cellulose Fibers2015Conference paper (Other academic)
  • 13.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Hagman, Joel
    RISE, Swerea.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    RISE, Swerea. Chalmers University of Technology, Sweden.
    Hagström, Bengt
    RISE, Swerea.
    Cosolvent and non-solvent effects on EmimAc-cellulose solutions’ rheology investigated inoscillatory shear and elongation2016In: 6th Avancell conference, 2016Conference paper (Other academic)
  • 14.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Untersuchungen zur Koagulation von Celluloselösungen / Investigations of coagulation of cellulose solutions2014Conference paper (Other academic)
  • 15.
    Härdelin, Linda
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Wet spun fibers from solutions of cellulose in an ionic liquid with suspended carbon nanoparticles2015In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, no 6, article id 41417Article in journal (Refereed)
    Abstract [en]

    Wet spun fibers from solutions of dissolving pulp in 1-ethyl-3-methylimidazolium acetate (EmimAc) with up to 50 wt % (based on cellulose) suspended carbon black and graphene nanoplatelets particles were studied. Carbon fillers were dispersed by simple shearing in a Couette type mixer and the resulting spin dope was extruded into a hot water coagulation bath from a single hole spinneret. Microstructure, mechanical properties, and electrical conductivity were assessed as a function of filler loading and discussed in comparison to melt spun fibers with similar fillers. The coagulation process and subsequent drying of wet spun fibers was found to produce a significant microporosity, more so the higher the filler loading. The electrical percolation threshold was quite high in the wet spun fibers and relatively modest values of conductivity were obtained with regard to the high filler loadings. Carbon black was found to be superior to graphene nanoplatelets. This was related to flow-induced orientation effects. The mechanical properties of the carbon-filled fibers were found to be similar or lower compared to the pure cellulose fibers because of low interfacial interactions and formation of microporosity.

  • 16.
    Härdelin, Linda
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Perzon, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Walkenström, Pernilla
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Gatenholm, P.
    Chalmers University of Technology.
    Influence of molecular weight and rheological behavior on electrospinning cellulose nanofibers from ionic liquids2013In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 130, no 4, p. 2303-2310Article in journal (Refereed)
    Abstract [en]

    Dissolving pulp was depolymerized with 2.5M HCl into cellulose fractions with decreasing molecular weight relative to acid treatment time. The cellulose fractions were dissolved at various concentrations in the ionic liquid 1-ethyl-3-methylimidazolium acetate (EmimAc) with co-solvent DMSO at ratio 1: 1 (w/w) and electrospun. Size exclusion chromatography was used to evaluate the molecular weight distributions and the rheological properties were characterized with a cone-and-plate rheometer. Scanning electron microscope was used to evaluate the fiber morphology, and thereby spinnability. Zero shear viscosity as a function of cellulose concentration show that all the solutions in this study are in the entangled semi-dilute regime; where the polymer concentration is large enough for significant overlap necessary for chain entanglement. However, within the intervals studied, neither cellulose concentration nor molecular weight seems to be decisive for if a solution can be electrospun into fibers or not. It is rather the viscosity of the solution that is decisive for electrospinnability, even though the solution is in the entangled semi-dilute regime. © 2013 Wiley Periodicals, Inc.

  • 17.
    Lund, A.
    et al.
    University of Borås, Sweden.
    Jonasson, Christian
    RISE, Swedish ICT, Acreo.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Haagensen, D.
    Chalmers University of Technology, Sweden.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Piezoelectric polymeric bicomponent fibers produced by melt spinning2012In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 126, no 2, p. 490-500Article in journal (Refereed)
    Abstract [en]

    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. Copyright © 2012 Wiley Periodicals, Inc.

  • 18. Lund, A
    et al.
    Nilsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Melt spun piezoelectric textile fibres demonstrated2013Conference paper (Other academic)
  • 19.
    Lund, Anja
    et al.
    Chalmers University of Technology, Sweden.
    Rundqvist, Karin
    University of Borås, Sweden.
    Nilsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Yu, Liyang
    Chalmers University of Technology, Sweden.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF. Chalmers University of Technology, Sweden.
    Müller, Christian
    Chalmers University of Technology, Sweden.
    Energy harvesting textiles for a rainy day: woven piezoelectrics based on melt-spun PVDF microfibres with a conducting core2018In: npj Flexible Electronics, Vol. 2, article id 9Article in journal (Refereed)
    Abstract [en]

    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.

  • 20.
    Nechyporchuk, Oleksandr
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Håkansson, Karl
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Gowda.V, Krishne
    KTH Royal Institute of Technology, Sweden.
    Lundell, Fredrik
    KTH Royal Institute of Technology, Sweden.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Continuous Assembly of Cellulose Nanofibrils and Nanocrystals into Strong Macrofibers through Microfluidic Spinning2018In: Advanced Materials Technologies, ISSN 2365-709X, article id 1800557Article in journal (Refereed)
    Abstract [en]

    Microfluidic fiber spinning is a promising technique for assembling cellulose nanomaterials into macroscopic fibers. However, its implementation requires upscalabe fabrication processes while maintaining high strength of the fibers, which could not be previously achieved. Herein, a continuous wet spinning process based on microfluidic flow focusing is developed to produce strong fibers from cellulose nanofibrils (CNFs) and nanocrystals (CNCs). Fibers with an average breaking tenacity as high as 29.5 cN tex−1 and Young's modulus of 1146 cN tex−1 are reported for the first time, produced from nonhighly purified CNF grades. Using the same developed method, wet spinning of fibers from CNCs is achieved for the first time, reaching an average Young's modulus of 1263 cN tex−1 and a breaking tenacity of 10.6 cN tex−1, thus exhibiting strength twice as high as that of common CNC films. A rather similar stiffness of CNC and CNF spun fibers may originate from similar degrees of alignment, as confirmed by wide-angle X-ray scattering (WAXS) and birefringence measurements, whereas lower strength may primarily arise from the shorter length of CNCs compared to that of CNFs. The benefit of CNCs is their higher solids content in the dopes. By combining both CNCs and CNFs, the fiber properties can be tuned.

  • 21. Nilsson, B
    et al.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Melt spun electrical conductive textilefibres with high carbon particles loading2014Conference paper (Other academic)
  • 22.
    Nilsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Rössler, Jochen
    University Medical Hospital, Germany.
    Electrically conductive fibres - recent development2016Conference paper (Other academic)
  • 23.
    Nilsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Lund, Anja
    Chalmers University of Technology, Sweden.
    Jonasson, Christian
    RISE, Swedish ICT, Acreo.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Poling and characterization of piezoelectric polymer fibers for use in textile sensors2013In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 201, p. 477-486Article in journal (Refereed)
    Abstract [en]

    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 s 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 15 nW. 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.

  • 24.
    Nilsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Oxfall, Henrik
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Wandelt, W.
    Rychwalski, R.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Electrically conductive textile fibres with hybridized graphite nanoplatelets and carbon black filler2012Conference paper (Other academic)
  • 25.
    Nilsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Oxfall, Henrik
    RISE, Swerea, IVF. Chalmers University of Technology.
    Wandelt, Wojciech
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Rychwalski, R.
    Chalmers University of Technology.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Melt spinning of conductive textile fibers with hybridized graphite nanoplatelets and carbon black filler2013In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 130, no 4, p. 2579-2587Article in journal (Refereed)
    Abstract [en]

    In this study, two different carbon fillers: carbon black (CB) and graphite nanoplatelets (GNP) are studied as conductive fillers for the preparation of conductive polypropylene (PP) nanocomposites. In order to obtain a homogenous dispersion of GNP, GNP/PP composites were prepared by two different methods: solid state mixing (SSM) and traditional melt mixing (MM). The result shows that MM is more efficient in the dispersion of GNP particles compared to SSM method. PP nanocomposites containing only one conductive filler and two fillers were prepared at different filler concentrations. Based on the analysis of electrical and rheological properties of the prepared nanocomposites, it shows that a hybridized composite with equal amounts of GNP and CB has favorable processing properties. Conductive fibers with a core/sheath structure were produced on a bicomponent melt spinning line. The core materials of these fibers are the hybridized GNP/CB/PP nanocomposite and the sheath is pure polyamide. It was found that GNPs were separated during melt and cold drawing which results in the decrease of conductivity. However, the conductivity could partly be restored by the heat treatment. © 2013 Wiley Periodicals, Inc.

  • 26.
    Nilsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Rigdahl, Mikael
    Chalmers University of Technology, Sweden.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Electrically conductive polymeric bi-component fibers containing a high load of low-structured carbon black2015In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, no 29, article id 42255Article in journal (Refereed)
    Abstract [en]

    Melt spinning at semi-industrial conditions of carbon black (CB) containing textiles fibers with enhanced electrical conductivity suitable for heating applications is described. A conductive compound of CB and high density polyethylene (HDPE) was incorporated into the core of bi-component fibers which had a sheath of polyamide 6 (PA6). The rheological and fiber-forming properties of a low-structured and a high-structured CB/HDPE composite were compared in terms of their conductivity. The low-structured CB gave the best trade-off between processability and final conductivity. This was discussed in terms of the strength of the resulting percolated network of carbon particles and its effect on the spin line stability during melt spinning. The conductivity was found to be further enhanced with maintained mechanical properties by an in line thermal annealing of the fibers at temperatures in the vicinity of the melting point of HDPE. By an adequate choice of CB and annealing conditions a conductivity of 1.5 S/cm of the core material was obtained. The usefulness of the fibers for heating applications was demonstrated by means of a woven fabric containing the conductive fibers in the warp direction. By applying a voltage of 48 V the surface temperature of the fabric rose from 20 to 30°C.

  • 27.
    Olsson, Carina
    et al.
    RISE, Swerea, IVF.
    Hagström, Bengt
    RISE, Swerea, IVF.
    Sjöholm, Elisabeth
    RISE, Innventia.
    Reimann, Anders
    RISE, Innventia.
    Carbon fibres from lignin-cellulose precursor2015In: 18th International Symposium on Wood, Fiber and Pulping Chemistry, September 9-11, 2015, Vienna, 2015, Vol. Poster, p. 126-129Conference paper (Other academic)
    Abstract [en]

    A series of two-component precursor fibres for carbon fibre production has been produced by air-gap spinning of kraft lignin with cellulose as the fibreforming polymer, the latter from paper grade or dissolving grade pulps. The spun precursor fibres,containing 70% lignin and 30% cellulose, demonstrate mechanical properties equivalent to commercial textile fibres. Precursor fibres based on softwood kraft lignin were treated thermally in twosteps to carbon fibres, which had mechanical properties equal to or greater than those reported for neat lignin-based carbon fibres produced by melt spinning. An advantage of the wet-spun precursor fibres developed in this project is that they are more flexible and easier to handle with a decreased risk ofbrittle fracture. The potential for further improvement for the new type of carbon fibre is very high.

  • 28.
    Olsson, Carina
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Sjöholm, Elisabeth
    RISE, Innventia.
    Reimann, Anders
    RISE, Innventia.
    Carbon fibres from lignin-cellulose precursor: Proceedings of the 18th International symposium on Wood2015In: Proceedings of the 18th International symposium onWood, Fiber and Pulping Chemistry, 2015Conference paper (Other academic)
  • 29.
    Rundqvist, Karin
    et al.
    University of Borås, Sweden.
    Sandsjö, Leif
    University of Borås, Sweden.
    Lund, Anja
    University of Borås, Sweden.
    Persson, Nils-Krister
    University of Borås, Sweden.
    Nilsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Registrering av fotnedsättning baserat på piezoelektriska fibrer2014Conference paper (Other academic)
  • 30.
    Strååt, Martin
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Boldizar, A.
    Chalmers University of Technology.
    Rigdahl, M.
    Chalmers University of Technology.
    Hagström, Bengt
    Swerea IVF Institute of Research.
    Improvement of melt spinning properties and conductivity of immiscible polypropylene/polystyrene blends containing carbon black by addition of styrene-ethylene-butene-styrene block copolymer2011In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 51, no 6, p. 1165-1169Article in journal (Refereed)
    Abstract [en]

    Conducting polymeric materials prepared from immiscible blends, such as polypropylene (PP)/polystyrene (PS), together with carbon black (CB), are known to have a relatively high electrical conductivity, because of a selective distribution of CB (double percolation). Melt spinning of immiscible blends containing CB has, however, not been extensively reported on previously. An immiscible 1:1 blend of PP and PS to which 4 wt% CB was added exhibited a very low melt draw-down ratio at rupture compared wit PP with the same content of CB. By adding 5 wt% SEBS (styrene-ethylene-butene-styrene block copolymer), the ultimate melt draw-down ratio increased about 10 times, which made the material more suitable for melt spinning. As-extruded samples of the immiscible blends (with CB) did not have higher electrical conductivities than PP/CB. A heat treatment increased the conductivity of immiscible PP/PS/CB composites, and longer treatment times and higher temperatures promoted the conductivity. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.

  • 31.
    Strååt, Martin
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Rigdahl, M.
    Chalmers University of Technology.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Conducting bicomponent fibers obtained by melt spinning of PA6 and polyolefins containing high amounts of carbonaceous fillers2012In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 123, no 2, p. 936-943Article in journal (Refereed)
    Abstract [en]

    Melt spinning of conductive polymer composites (CPCs) is coupled with some difficulties such as a decrease of conductivity upon drawing and a reduced spinnability with increasing filler concentration. Applying bicomponent technology may provide the possibility to produce fibers from CPCs with a high filler concentration. A pilot-scale bicomponent melt spinning set-up was used to produce core/sheath fibers with fiber titers between 13 and 47 dtex. The sheath material was polyamide 6 (PA6) or polypropylene (PP) and the core material was a CPC. Two CPCs were used, polypropylene (PP) with carbon black (CB), denoted by PP/CB, and polyethylene (PE) with multiwalled carbon nanotubes (MWNT), denoted by PE/MWNT. The results showed that both materials could be used with a filler concentration of 10 wt % to obtain melt draw ratios up to 195. The volumetric fraction of core material in the bicomponent structure was 28%. A heat treatment of PP/CB fibers restored the conductivity to the level of the undrawn material, corresponding to an increase in conductivity by a factor 5. The same heat treatment had a positive effect on the conductivity of PE/MWNT fibers although the conductivity was not restored. © 2011 Wiley Periodicals, Inc.

  • 32.
    Strååt, Martin
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Toll, Staffan
    Boldizar, Antal
    Chalmers University of Technology.
    Rigdahl, Mikael
    Chalmers University of Technology.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Melt spinning of conducting polymeric composites containing carbonaceous fillers2011In: Journal of Applied Polymer Science, ISSN 00218995, Vol. 119, no 6, p. 3264-3272Article in journal (Refereed)
    Abstract [en]

    Fibers produced by melt spinning of conductive polymer composites are attractive for several applications; the main drawback is however reduced processability at high filler concentrations. Carbon nanotubes (CNTs) are considered suitable fillers for conductive polymer composites, replacing conductive grades of carbon black (CB). In this study, the fiber-forming properties of conductive polymer composites based on a conductive grade of CB and two masterbatches with CNT in a polyethylene matrix were investigated. The CB was also used in a polypropylene matrix for comparison. The rheological properties of the filler-containing melts in shear and their extensional behavior were evaluated. A piston-driven device was used to extrude the molten materials through a capillary; different capillary geometries were tested. Fibers were produced at various draw ratios, and their conductivity was determined. To assess the ultimate extensibility, a modified Rheotens method was used. The results showed that a conductive CB grade can have a lower percolation threshold and higher conductivity than a material with CNT. Conductivity decreased with increasing melt draw ratio for both types of fillers. The spinnability of the materials decreased with increasing concentration of filler material and correlations were found between spinnability and melt elasticity.

  • 33.
    Åkesson, D.
    et al.
    University College of Borås.
    Skrifvars, M.
    University College of Borås.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Walkenström, Pernilla
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Seppälä, J.
    Helsinki University of Technology.
    Processing of structural composites from biobased thermoset resins and natural fibres by compression moulding2009In: Journal of Biobased Materials and Bioenergy, ISSN 1556-6560, E-ISSN 1556-6579, Vol. 3, no 3, p. 215-225Article in journal (Refereed)
    Abstract [en]

    With the aim of producing composites from renewable materials for the furniture industry, a number of thermoset prepregs were manufactured and evaluated. The applicability of two different biobased thermoset resins was evaluated. The first resin is based on soybean oil and the second on lactic acid. Both resins are cross-linkable and produced from renewable resources. Prepregs were manufactured from the two resins together with natural fibres (flax and cellulose). Furthermore, sheet moulding compound (SMC) was developed from lactic acid based resin together with glass fibre. Seat shells were produced from the prepregs by compression moulding. Curing of the composites was monitored using a response surface methodology. Further, the fibre ratio, mechanical properties as well as adhesion between the matrix and the fibre were evaluated. These prepregs offers short cycle times and yield products with suitable mechanical properties. Issues related to the preparation and the processing of the prepregs are discussed in the article. Copyright © 2009 American Scientific Publishers.

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