| 1. |
- Guo, Zengwei, et al.
(author)
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Preparation of polypropylene/nanoclay composite fibers
- 2013
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In: Polymer Engineering and Science. - : Wiley. - 0032-3888 .- 1548-2634. ; 53:10, s. 2035-2044
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Journal article (peer-reviewed)abstract
- 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.
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| 2. |
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| 3. |
- Härdelin, Linda, 1977, et al.
(author)
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Influence of molecular weight and rheological behavior on electrospinning cellulose nanofibers from ionic liquids
- 2013
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In: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 130:4, s. 2303-2310
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Journal article (peer-reviewed)abstract
- 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.
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| 4. |
- Härdelin, Linda, 1977, et al.
(author)
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Wet Spun Fibers from Solutions of Cellulose in an Ionic Liquid with Suspended Carbon Nanoparticles
- 2015
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In: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 132:6
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Journal article (peer-reviewed)abstract
- 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.
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| 5. |
- Larsson, Bengt, et al.
(author)
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Molecular oxygen in the rho Ophiuchi cloud
- 2007
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In: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 466:3, s. 5-
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Journal article (peer-reviewed)abstract
- Context: Molecular oxygen, O2, has been expected historically to be an abundant component of the chemical species in molecular clouds and, as such, an important coolant of the dense interstellar medium. However, a number of attempts from both ground and from space have failed to detect O2 emission.Aims: The work described here uses heterodyne spectroscopy from space to search for molecular oxygen in the interstellar medium. Methods: The Odin satellite carries a 1.1 m sub-millimeter dish and a dedicated 119 GHz receiver for the ground state line of O2. Starting in 2002, the star forming molecular cloud core ρ Oph A was observed with Odin for 34 days during several observing runs.Results: We detect a spectral line at v_LSR =+3.5 km s-1 with Δ v_FWHM=1.5 km s-1, parameters which are also common to other species associated with ρ Oph A. This feature is identified as the O2 (NJ = 11 - 1_0) transition at 118 750.343 MHz.Conclusions: The abundance of molecular oxygen, relative to H{2} , is 5 × 10-8 averaged over the Odin beam. This abundance is consistently lower than previously reported upper limits.Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Étude Spatiale (CNES). The Swedish Space Corporation has been the industrial prime contractor and also is operating the satellite. Appendix A is only available in electronic form at http://www.aanda.org
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| 6. |
- Lund, Anja, 1971, et al.
(author)
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A study on melt spinning of potentially electroactive textile fibres, and the influence of melt spinning parameters on molecular structure development
- 2009
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In: Poster186-P, PPS-2009, Europe /Africa Regional Meeting, Larnaca, Cyprus, October 18-21, 2009.
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Conference paper (other academic/artistic)
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| 7. |
- Lund, Anja, et al.
(author)
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Melt spinning of beta-phase poly(vinylidene fluoride) yarns with and without a conductive core
- 2011
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In: Journal of Applied Polymer Science. - : Wiley Periodicals, Inc.. - 0021-8995 .- 1097-4628. ; 120:2, s. 1080-1089
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Journal article (peer-reviewed)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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| 8. |
- Lund, Anja, et al.
(author)
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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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In: Journal of Applied Polymer Science. - : Wiley Periodicals, Inc. - 0021-8995 .- 1097-4628. ; 116:5, s. 2685-2693
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Journal article (peer-reviewed)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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| 9. |
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| 10. |
- Lund, Anja, et al.
(author)
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Piezoelectric polymeric bicomponent fibers produced by melt spinning
- 2012
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In: Journal of Applied Polymer Science. - : Wiley Periodicals, Inc.. - 0021-8995 .- 1097-4628. ; 126:2, s. 490-500
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Journal article (peer-reviewed)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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