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Träfflista för sökning "WAKA:kon ;lar1:(hb);pers:(Berglin Lena)"

Sökning: WAKA:kon > Högskolan i Borås > Berglin Lena

  • Resultat 1-10 av 24
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1.
  • Baghaei, Behnaz, et al. (författare)
  • Hemp/PLA Co-Wrapped Hybrid Yarns For Structured Thermoplastic Composites
  • 2013
  • Konferensbidrag (refereegranskat)abstract
    • In recent years, natural fibre-reinforced polymer composites have been attracting attention from the viewpoint of reducing the impact on the natural environment. Currently, the use of thermoplastic resins in composites is clearly of higher potential than the use of thermoset. There are many thermoplastic polymers derived from renewable raw materials, which are also biodegradable. Polylactic acid (PLA) is one such candidate, and it shows rather good properties that are suitable for applications that do not require long-term durability or elevated mechanical performance at higher temperatures. In order to make their possible use in many technical applications more attractive, the mechanical properties of the PLA can be enhanced by using reinforcements. Hemp fibres can be considered to be a good choice for reinforcing polymer composites, due to their high stiffness, strength, and aspect ratio. Highly ordered textile reinforcements, such as interlaced woven fabrics and unidirectional fabrics made from natural-fibre yarns, perform considerably better than random non-woven mats in natural-fibre composites. At present, the commercially available plant-fibre yarns are not intended for structural composites, but for textiles, which have entirely different demands on the yarns. Thus, work is needed to tailor-make the best plant-fibre yarn for reinforcement of composites. This also includes investigation of the possibility of combining plant-fibre yarns with the matrix polymer in fibre form into one hybrid yarn (a composite preform), and how to do it (twisting or blending). It is well known that fibres provide the highest strength and stiffness when they are continuous and aligned in the direction of the applied load. Natural fibres are naturally discontinuous and conventional spun staple yarns tend to be highly twisted, which leads to fibre misalignment and poor resin wet-out. The structured natural-fibre composites reported so far are based on twisted yarns produced by long-established conventional spinning methods, mainly ring spinning. In this paper, we report our work on improving the orientation of hemp fibres in composites by using our recent development of co-wrapped yarn structures. This novel co-wrapped yarn consists of low twist and very fine hemp yarns next to PLA filaments in the core part, which are wrapped by PLA filaments. By varying the composition of hybrid yarn, it is possible to vary the hemp fibre content from 10 to 45 wt %. An exciting recent advancement has been a new family of aligned natural-fibre reinforcements, which has overcome these issues by using low twist yarns. We also report the influence of fibre content and wrap density (number of wraps per unit length) on the properties of composites. Before compression moulding, multilayer 0/90 bidirectional hybrid yarn prepregs were prepared by winding the hybrid yarn around a steel rectangular frame. We investigated the mechanical and thermo-mechanical properties of hemp-reinforced PLA composites. Compared to neat PLA, the tensile and flexural modulus and the strength of the PLA-hemp composites were significantly higher as a result of the increased fibre content. Impact strength of the composites decreased initially up to 10 wt % fibre loading, but even higher fibre loading caused an improvement in impact strength. From the DMTA results, it is evident that incorporation of the fibres gives a considerable increase in storage modulus and a decrease in tan δ values. These results show the reinforcing effect of hemp on PLA matrix. From the general trend in the results obtained, it can be affirmed that co-wrapped hybrid yarn with lower wrapping density leads to lower mechanical properties in the composite. The study performed with DSC revealed that the glass transition temperature and the crystalline melting point of PLA were not affected significantly after reinforcement with hemp. The crystallisation temperature of the hemp-reinforced PLA composites decreased compared to pure PLA, which indicates that the hemp fibres hinder the migration and diffusion of PLA molecular chains to the surface of the nucleus in the composites. No noteworthy differences in calorimetric data from DSC for composites were observed between the hybrid yarn preforms with different wrapping density. Future work will concentrate on efforts to evaluate the biodegradability of these developing and promising composites.
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  • Baghaei, Behnaz, et al. (författare)
  • Tailoring of the mechanical and thermal properties of hemp/PLA hybrid yarn composites
  • 2013
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • In this study, we worked on improving the orientation of hemp fibres in composites by using our recent development of co-wrapped yarn structures. We investigated the influence of fibre content and wrap density on the properties of composites. Composites were fabricated by compression moulding of 0/90 bidirectional prepregs. Compared to neat PLA, the tensile and flexural modulus and the strength of the PLA-hemp composites were significantly higher as a result of the increased fibre content. Impact strength of the composites decreased initially up to 10 mass % fibre loading, but even higher fibre loading caused an improvement in impact strength. From the DMTA results, it was evident that incorporation of the fibres gives a considerable increase in storage modulus and a decrease in tan δ values. From the general trend in the results obtained, it can be affirmed that co-wrapped hybrid yarn with lower wrapping density leads to lower mechanical properties in the composite. The study performed with DSC revealed that the crystallisation temperature of the hemp-reinforced PLA composites decreased compared to pure PLA, which indicates that the hemp fibres hinder the migration and diffusion of PLA molecular chains to the surface of the nucleus in the composites.
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4.
  • Berglin, Lena (författare)
  • Designing for extreme conditions
  • 2008
  • Ingår i: In Proceedings of Cumulus Design Conference 28-31 march 2008, Kyoto, Japan.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • This paper describes a project where experimental product design has been used in order to find out how to create textile products with a double function for an extreme context regarding hard weather conditions. A concept was defined using interviews of professional that daily have to survive extreme working conditions. An overall impression from the interviews was that the use of equipment to manage the exposed situation is limited and functional to fulfil a few important needs. The concept was developed into a set of advanced textile structures and products with a double function and the aim to save people in extreme environments. These structures are general which are shown in examples where these textiles maintain ordinary daily live activities.
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  • Berglin, Lena, et al. (författare)
  • Textile Sound Structures
  • 2008
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • In this paper we describe a set of sound sensitive structures based on piezoelectric technique. We have laminated piezoelectric polymer films between layers of different textile fabric structures. The initial results show that these structures register sound and the signal quality depends on the laminate set-up. Textile sound structures offer a variety of possible applications such as active sound absorbers and heart rate monitoring.
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  • Eriksson, Siw, et al. (författare)
  • Three-dimensional multilayer fabric structures for interactive textiles
  • 2011
  • Ingår i: 3rd World Conference on 3D Fabrics and Their Applications; Wuhan; China; 20 April 2011 through 21 April 2011. - 9781846260490 ; , s. 63-67
  • Konferensbidrag (refereegranskat)abstract
    • Abstract. The integration of performances in interactive textile fabric system has so far been rather complicated since they are based on multilayer or three-dimensional principles. These structures are today mainly put together by means of several processes, which is laborious and time consuming. In this interdisciplinary study we have combined the principle of a three-dimensional multilayer weaving process and interactive textiles structures in order to enable the manufacturing of interactive textile structure in one process. The process is investigated using a manual reconstructed loom and the approach has been to use the 3D structures in order to integrate and organize conductive and compressive spacer layers as a textile capacitive structure. Measurements on such a structure was done by construction a first order passive high pass filter and using the fabric sample as the capacitor and a 1MΩ resistor. The behavior of the measurement of the capacitive sensor is quite close to the theoretical calculation and already at this stage the structure might be used to indicate the presence of a pressure. In this project we have shown that a three-dimensional structure enables the development of interactive textiles in one process. Further the concept of using a rebuilt manual loom has shown great potential in early research stages. It is considerable saving time and resources since, in this case, it is easy to reconstruct the loom design compared to performing similar reconstruction on a machine. Future research will focus on developing other types of interactive structures. Another issue will be to scale down the size of the structures in order to get thinner and more flexible qualities.
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8.
  • Eriksson, Siw, et al. (författare)
  • Tredimensionell vävteknik med möjliga tillämpningar inom medicinsk teknik
  • 2011
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Integreringen av interaktiva egenskaper i teknisk textil har rönt stort intresse inom textil-forskningen de senaste åren. Med interaktiva textila strukturer avses textila system som interagerar med sin omgivning i någon mening. Ett sätt att åtadkomma dessa interaktiva strukturer är att foga samman lager av olika struktur eller material där varje lager tillför textilen/det textila systemet olika egenskaper. Det typiska tillvägagångssättet för att sammanfoga olika lager av textila material är att använda någon form av lamineringsteknik. Föreliggande projekt rör en ny vävteknik som möjliggör att flera textila lager med olika egenskaper vävs samman i en och samma process utan de tillsatser eller extra hantering som krävs vid laminering. Utöver de uppenbara produktionstekniska fördelarna möjliggör kombinationen av olika egenskaper i en lagerstruktur också att speciella krav på slutprodukten lättare kan tillgodoses. Det medicintekniska området förväntas ha stor nytta av textila strukturer som kan utformas i tre dimensioner eller kombinera olika egenskaper i en och samma struktur. Syftet är att demonstrera hur en nyutvecklad vävteknik för tredimensionella strukturer kan tillämpas för att tillverka interaktiva textila strukturer i en och samma tillverkningsprocess. I detta delprojekt har den tredimensionella tekniken använts för att utveckla en kapacitiv struktur utformad helt i textil. Genom mindre modifieringar av och tillägg till en 16-skaftad datorstyrd manuell prototypvävstol har två ledande och ett isolerande skikt kombinerats för att realisera en textilbaserad kondensator. I ett första test realiserades ett enkelt högpassfilter med den kapacitiva textila strukturen som kondensator. Filtrets egenskaper visade sig väl följa den förväntade filterkarakteristiken. Den nyutvecklade tredimensionella vävtekniken förväntas ha stora tillämpningsmöjligheter inom det medicintekniska området.
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  • Resultat 1-10 av 24

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