Endre søk
Begrens søket
1234 1 - 50 of 177
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Adekunle, Kayode
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Åkesson, Dan
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Biobased Composites Prepared by Compression Molding with a Novel Thermoset Resin from Soybean Oil and a Natural-Fiber Reinforcement2010Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 116, nr 3, s. 1759-1765Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biobased composites were manufactured with a compression-molding technique. Novel thermoset resins from soybean oil were used as a matrix, and flax fibers were used as reinforcements. The air-laid fibers were stacked randomly, the woven fabrics were stacked crosswise (0/90 ), and impregnation was performed manually. The fiber/resin ratio was 60 : 40. The prepared biobased composites were characterized by impact and flexural testing. Scanning electron microscopy of knife-cut cross sections of the specimens was also done to investigate the fiber–matrix interface. Thermogravimetric analysis of the composites was carried out to provide indications of thermal stability. Three resins from soybean oil [methacrylated soybean oil, methacrylic anhydride modified soybean oil (MMSO), and acetic anhydride modified soybean oil] were used as matrices. The impact strength of the composites with MMSO resin reinforced with air-laid flax fibers was 24 kJ/m2, whereas that of the MMSO resin reinforced with woven flax fabric was between 24 and 29 kJ/m2. The flexural strength of the MMSO resin reinforced with air-laid flax fibers was between 83 and 118 MPa, and the flexural modulus was between 4 and 6 GPa, whereas the flexural strength of the MMSO resin reinforced with woven fabric was between 90 and 110 MPa, and the flexural modulus was between 4.87 and 6.1 GPa.

  • 2.
    Adekunle, Kayode
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Åkesson, Dan
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Preparation of biobased composites using novel thermoset polymers from soybean oil and a natural fibre reinforcement2009Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Health related issues, stringent environmental protection policies, search for cost effective and alternative materials, crave for renewability and sustainability and quest for high performance materials for structural applications give the motivation for research in polymer composites and material science. Due to the health, safety and environmental concerns over the conventional synthetic materials and the legislation against their usage both in domestic and industrial applications, alternatives sources that will be comparable in properties are being sought. There is an emerging market for biodegradable polymers which is expected to increase substantially in the coming years.[1] Preparation of Composites Airlaid and woven flax fibre mats were first treated with 4% sodium hydroxide solution for one hour and then washed with plenty of water. This was done in order to remove any residual impurities. The fibres were dried at room temperature for 24 hr and then dried in a vacuum oven for 1hr at a temperature of 105°С. The 8 sheets of the fibre were hand laid cross- wisely and the impregnation was done manually. The fibre/ resin ratio was about 60% to 40%. Methacrylated soybean oil, methacrylic anhydride and acetic anhydride modified soybean oil were the synthesized matrices used. The compression moulding was done at a temperature of 170°С for 5 min at 40bar. Characterisations The tensile testing was performed based on an ISO-test method for tensile tests on plastic materials. The Charpy impact strength of unnotched specimens was evaluated in accordance with ISO 179 using a Zwick test instrument and scanning electron microscopy analysis was done on the fractured specimens. The composites showed various mechanical properties, having impact strengths between 24 and 63 kJ/m² and tensile strength up to 51MPa.

  • 3.
    Adekunle, Kayode
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Åkesson, Dan
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Synthesis of reactive soybean oils for use as biobased thermoset resins in structural natural fibre composites2008Konferansepaper (Fagfellevurdert)
  • 4.
    Adekunle, Kayode
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Åkesson, Dan
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Synthetic modification of reactive soybean oils for use as biobased thermoset resins in structural natural fiber composites2008Konferansepaper (Annet vitenskapelig)
  • 5.
    Adekunle, Kayode
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Åkesson, Dan
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Synthetic modification of reactive soybean oils for use as biobased thermoset resins in structural natural fiber composites2008Inngår i: Polymer Preprints, ISSN 0551-4657, Vol. 49, nr 1, s. 279-Artikkel i tidsskrift (Fagfellevurdert)
  • 6.
    Ahlström, Peter
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Aim, Karel
    Dohrn, Ralf
    Elliott, J. Richard
    Jackson, George
    Jaubert, Jean-Noel
    Rebello de A. Macedo, Maria Eugénia
    Pokki, Juha-Pekka
    Reczey, Kati
    Victorov, Alexey
    Fele Zilnik, Ljudmila
    Economou, Ioannis
    A Survey of Thermodynamics and Transport Properties in Chemical Engineering Education in Europe and the USA2008Inngår i: Proceedings of the 100th Annual Meeting of the American Institute for Chemical Engineering, 2008Konferansepaper (Fagfellevurdert)
  • 7.
    Ahlström, Peter
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Gebäck, Tobias
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Johansson, Erik
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Water absorption in polymers2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    In this work two different examples of water absorbtion in polymers are studied by Monte Carlo simulations. Both of them are of large technical and commercial impotance. The first example is the water absorption in polyethylene cables where the water absorption plays a crucial role in the degradation of the cable insulation and thus should be as low as possible. The second example is bio-based superabsorbents made from denatured protein where water absorption capability is the prime desired property. Methods Gibbs Ensemble Monte Carlo simulations [1] were used to study the hydration of polymers. All simulations are performed with two boxes, one of which is filled with water at the start of the simulation, whereas the other contains polymer molecules and possible ions. The polymer molecules are not allowed to swap boxes whereas the water molecules are allowed to do so thus constituting an osmotic Gibbs ensemble [2]. For the polyethylene a connectivity-altering algorithm was used whereas the protein molecules were simulated using a side-chain regrowth model in addition to traditional Monte Carlo moves. For the polyethylene, the TraPPE [3] force field was used and the protein molecules, the Amber force field [4] was used. Water was modelled using simple point charge models [5]. Electrostatic interactions are treated using Ewald summation methods. The protein molecules were of different amino acid compositions and in different conformations, e.g., β-turns and random coils obtained using the amorphous cell method[6]. Studies were made with different degrees of charging on, e.g., lysine side chains mimicking different ionization states. Results The studies of polyethylene revealed the importance of ions left from the polymerisation catalyst for the absorbtion of water and the concomitant degradation of polyethylene cable insulation. Also the absorption properties of the protein molecules is strongly related to the presence of charged groups and fully charged protein molecules absorb large amounts of water. However, neither native nor denatured protein molecules show superabsorbing properties (i.e. absorbing hundreds of times their own mass) as they show in experimental studies and the reasons for this discrepancy will be discussed. References 1. A.Z. Panagiotopoulos, Mol. Phys. 61, 813 (1987). 2. E. Johansson, K. Bolton, D.N. Theodorou, P. Ahlström, J. Chem. Phys., 126, 224902 (2007). 3. M.G. Martin, and J.I. Siepmann, J. Phys. Chem. B, 103, 4508-4517 (1999). 4. W.D. Cornell, P. Cieplak, C.I. Bayly, I.R. Gould, K.M. Merz Jr, D.M. Ferguson, D.C. Spellmeyer, T. Fox, J.W. Caldwell, P.A. Kollman (1995). J. Am. Chem. Soc. 117, 5179–5197. 5. H. J. C. Berendsen, J. P. M. Postma and W. F. van Gunsteren, in Intermolecular Forces, B. Pullman, ed. (Reidel, Dordrecht, 1981) p. 331; H. J. C. Berendsen, J. R. Grigera and T. P. Straatsma, J. Phys. Chem. 91, 6269 (1987). 6. D.N. Theodorou, U.W. Suter, Macromolecules, 18, 1467 (1985).

  • 8.
    Ahlström, Peter
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Moodley, Suren
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ramjugernath, D.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Computer Simulations of Vapor-Liquid-Liquid Equilibria Involving Hydrocarbons and Water2008Inngår i: Proceedings of the 100th Annual Meeting of the American Institute for Chemical Engineering, 2008, CHPC National Meeting, Durban, South Africa, December 9-10, 2008, AlChe Annual Meeting, Philadelphia, November 15-21, 2008, 2008Konferansepaper (Annet vitenskapelig)
  • 9. Ali, Majid
    et al.
    Bashir, Tariq
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Persson, Nils-Krister
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Optimization of oCVD Process for the Production of Conductive Fibers2011Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Electro active textile fibers are key components in smart and interactive textile applications. In our previous study, we produced poly(3,4-ethylenedioxythiophene) (PEDOT) coat edviscose fibers by using oxidative chemical vapordeposition (OCVD) technique. We tried FeCl3 as oxidant and found optimum reaction conditions at which better electrical as well as mechanical properties of conductive fibers could be achieved.

  • 10. Ali, Majid
    et al.
    Bashir, Tariq
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Persson, Nils-Krister
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Stretch Sensing Properties of PEDOT Coated Conductive Yarns Produced by OCVD Process2011Konferansepaper (Fagfellevurdert)
  • 11.
    Arja, Mina
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Akbar Mirzaei, Ali
    University of Sistan and Baluchestan, Zahedan 98135-674, Iran.
    Mahmood Davarpanah, Abdol
    University of Sistan and Baluchestan, Zahedan 98135-674, Iran.
    Masoud Barakati, Seyed
    University of Sistan and Baluchestan, Zahedan 98135-674, Iran.
    Mohsenzadeh, Abas
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Atashi, Hossein
    University of Sistan and Baluchestan, Zahedan 98135-674, Iran.
    Bolton, Kim
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    DFT studies of hydrocarbon combustion on metal surfaces2018Inngår i: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 24, s. 47-Artikkel i tidsskrift (Fagfellevurdert)
  • 12.
    Baghaei, Behnaz
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Berglin, Lena
    Högskolan i Borås, Institutionen Textilhögskolan.
    Hybrid natural fibre reinforcements and prepregs for thermoplastic composites with improved performance and properties2014Konferansepaper (Annet vitenskapelig)
  • 13.
    Baghaei, Behnaz
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Berglin, Lena
    Högskolan i Borås, Institutionen Textilhögskolan.
    Manufacture and characterisation of thermoplastic composites made from PLA/hemp co-wrapped hybrid yarn prepregs2013Inngår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 50, s. 93-101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PLA/hemp co-wrapped hybrid yarns were produced by wrapping PLA filaments around a core composed of a 400 twists/m and 25 tex hemp yarn (Cannabis Sativa L) and 18 tex PLA filaments. The hemp content varied between 10 and 45 mass%, and the PLA wrapping density around the core was 150 and 250 turns/metre. Composites were fabricated by compression moulding of 0/90 bidirectional prepregs, and characterised regarding porosity, mechanical strength and thermal properties by dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC). Mechanical tests showed that the tensile and flexural strengths of the composites markedly increased with the fibre content, reaching 59.3 and 124.2 MPa when reinforced with 45 mass% fibre, which is approximately 2 and 3.3 times higher compared to neat PLA. Impact strength of the composites decreased initially up to 10 mass% fibre; while higher fibre loading (up to 45 mass%) caused an increase in impact strength up to 26.3 KJ/m2, an improvement of about 2 times higher compared to neat PLA. The composites made from the hybrid yarn with a wrapping density of 250 turns/metre showed improvements in mechanical properties, due to the lower porosity. The fractured surfaces were investigated by scanning electron microscopy to study the fibre/matrix interface.

  • 14.
    Baghaei, Behnaz
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Salehi, Masoud
    Bashir, Tariq
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Rissanen, Marja
    Nousiainen, Pertti
    Novel aligned hemp fibre reinforcement for structural biocomposites: Porosity, water absorption, mechanical performances and viscoelastic behaviour2014Inngår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 61, s. 1-12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper examines the thermal and mechanical behaviour as well as moisture absorption of aligned hemp composites using hemp/PLA wrap spun yarns. Uniaxial composites were fabricated with 30 mass% hemp using compression moulding. The properties of composites in terms of hemp fibre orientation (aligned and random), off-axis angle and alkali treatment were investigated. It was found that the testing direction influenced the mechanical properties of the composites. Compared with all the fabricated composites, the aligned alkali hemp/PLA yarn composite possessed the best mechanical properties, including tensile, flexural and impact strengths, lower porosity and water absorption. The water absorption for all composites was higher than for neat PLA, both at room temperature and 80 C. The PLA in its treated composites had higher crystallinity, which was attributed to effective heterogeneous nucleation induced by hemp. Based on SEM observation and theoretical analysis of DMTA data, there was a favourable interfacial adhesion in all composites.

  • 15.
    Bakare, Fatimat
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Åkesson, Dan
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bashir, Tariq
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ingman, Petri
    Srivastava, Rajiv
    Synthesis and characterization of unsaturated lactic acid based thermoset bio-resins2014Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 67, s. 570-582Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bio-based thermoset resins have been synthesized using lactic acid oligomers, which were functionalized with carbon–carbon double bonds, in order to allow their crosslinking by a free radical mechanism. Two different resin structures were synthesized. One resin was composed of an allyl alcohol terminated lactic acid oligomer, which was end-functionalized with methacrylic anhydride (MLA resin). The second resin was a mixture of the same allyl alcohol-lactic acid oligomer, and penthaerythritol. This mixture was end-functionalized with methacrylic anhydride, in order to get a methacrylate functionalized lactic acid oligomer, and methacrylate functionalized penthaerythritol (PMLA resin). The synthesized resins were characterized using FT-IR, 1H NMR and 13C NMR spectroscopy, differential scanning calorimetry as well as dynamic mechanical analysis to confirm the resin structure and reactivity. The flow viscosities were also measured in order to evaluate the suitability of the resins to be used as a matrix in composite applications. The results showed that the PMLA resin has better mechanical, thermal and rheological properties than the MLA resin, and both had properties which were comparable with a commercial unsaturated polyester resin. The high biobased content of 90% and the high glass transition temperature at 100 °C for the PMLA resin makes it an attractive candidate for composite applications where crude oil based unsaturated polyester resins are normally used.

  • 16.
    Barghi, Hamidreza
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Functionalization of Synthetic Polymers for Membrane Bioreactors2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Membrane bioreactors (MBRs) show great promise for productivity improvement and energy conservation in conventional bioprocesses for wastewater reclamation. In order to attain high productivity in a bioprocess, it is crucial to retain the microorganisms in the bioreactors by preventing wash out. This enables recycling of the microorganisms, and is consequently saving energy. The main feature of MBRs is their permeable membranes, acting as a limitative interface between the medium and the microorganisms. Permeation of nutrients and metabolites through the membranes is thus dependent on the membrane characteristics, i.e. porosity, hydrophilicity,and polarity. The present thesis introduces membranes for MBRs to be used in a continuous feeding process, designed in the form of robust, durable, and semi-hydrophilic films that constitute an effective barrier for the microorganisms, while permitting passage of nutrients and metabolites. Polyamide 46 (polytetramethylene adipamide), a robust synthetic polymer, holds the desired capabilities, with the exception of porosity and hydrophilicity. In order to achieve adequate porosity and hydrophilicity, bulk functionalization of polyamide 46 with different reagents was performed. These procedures changed the configuration from dense planar to spherical, resulting in increased porosity. Hydroxyethylation of the changed membranes increased the surface tension from 11.2 to 44.6 mJ/m2. The enhanced hydrophilicity of PA 46 resulted in high productivity of biogas formation in a compact MBR, due to diminished biofouling. Copolymerization of hydrophilized polyamide 46 with hydroxymethyl 3,4-ethylenedioxythiophene revealed electroconductivity and hydrophilic properties, adequate for use in MBRs. To find either the maximal pH stability or the surface charge of the membranes having undergone carboxymethylation, polarity and the isoelectric point (pI) of the treated membranes were studied by means of a Zeta analyzer. The hydroxylated PA 46 was finally employed in a multilayer membrane bioreactor and compared with hydrophobic polyamide and PVDF membranes. The resulting biogas production showed that the hydroxylated PA 46 membrane was, after 18 days without regeneration, fully comparable with PVDF membranes.

  • 17.
    Barghi, Hamidreza
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Catalytic Synthesis of Bulk Hydrophilic Acetaldehyde-Modified Polyamide 462014Inngår i: Current Organic Synthesis, ISSN 1570-1794, E-ISSN 1875-6271, Vol. 11, nr 6, s. 288-294Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hydrophilization of Polyamide 46 (PA46) via modification with acetaldehyde in continuous phase was studied. The chemical modification of PA 46 with acetaldehyde resulted in a water-swollen polymer with hydrophilic property. The polyamide 46 undergoes a nucleophilic addition with acetaldehyde in the presence of aluminum chloride as a catalyst. The extent of bulk hydroxyethylation using AlCl3 resulted in 95.65% modification counted as total N-hydroxyethylated polyamide 46. The modification resulted in improved hydrophilic properties, and a maximum surface free energy of 44.6 mJ/m2 was achieved after 3 h reaction, whereas the unmodified PA46 had a surface free energy of 11.2 mJ/m2. In addition, thermal properties of the polymers were studied using differential scanning calorimetry and thermogravimetric analyses. The functionalization leads to decrease in the crystallization energy from 88 J/g to 51 J/g, while the melting energy is changed from 110 J/g to 53 J/g. Furthermore, the thermal stability of the PA46 to pyrolysis was diminished after hydroxylation.

  • 18.
    Bashir, Tariq
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ali, Majid
    Persson, Nils-Krister
    Högskolan i Borås, Institutionen Textilhögskolan.
    Ramamoorthy, Sunil Kumar
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Stretch Sensing Properties of Conductive Knitted Structures of PEDOT-coated Viscose and Polyester Yarns2013Inngår i: Textile research journal, ISSN 0040-5175, E-ISSN 1746-7748, Vol. 84, nr 3, s. 323-334Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wearable textile-based stretch sensors for health-care monitoring allow physiological and medical evaluation without interfering in the daily routine of the patient. In our previous work, we successfully coated viscose and polyester (PES)fibers with the conjugated polymer poly(3,4-ethylenedioxythiophene) (PEDOT), using a chemical vapor deposition (CVD) process. In the present paper we report the possibility of producing a large quantity of PEDOT-coated conductive fibers with acceptable mechanical strength and frictional properties, so that knitted stretch sensors can be produced. In utilizing these knitted structures we have demonstrated the possibility of producing a textile-based monitoring device which is more readily integrated into wearable clothing than the previous metal-containing structures. The performance of viscose and PES knitted structures as stretch sensors has been investigated using a cyclic tester of our own design. For imitation of respiratory and joint movement, the variation in electrical properties of the knitted structures was examined at 5 to 50% elongation, and the performance of knitted viscose and PES structures was then compared on the basis of the cyclic testing results. In order to determine the effect of washing on PEDOT coatings and the knitted structures, two washing cycles were performed. After washing, the persistence of PEDOT coating on knitted structures was investigated using FT–IR spectroscopy and thermogravimetric analysis. In the case of PES fiber, it was revealed that stretch sensing behavior persisted even after the washing cycles. These structures thus have the potential to be utilized in medical textiles for monitoring the physiological activities of patients, such as breathing rate and joint movement.

  • 19.
    Bashir, Tariq
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bakare, Fatimat
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Baghaei, Behnaz
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Mehrjerdi, Adib Kalantar
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Influence of different organic solvents and oxidants on insulating and film-forming properties of PEDOT polymer2013Inngår i: Iranian polymer journal, ISSN 1026-1265, E-ISSN 1735-5265, Vol. 22, nr 8, s. 599-611Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Processing of conjugate polymers has always been a challenge because of their poor solubility and infusibility in organic and inorganic solvents. The processibility and applications of intrinsically conductive polymers (ICPs) can be enhanced by producing their solutions or dispersions in different suitable solvents. It can also be achieved by preparing un-doped or electrically neutral polymers, which can further be transformed in semiconductor after oxidation/reduction reaction. The present study focuses on the preparation of active dispersions of poly (3,4-ethylenedioxythiophene) (PEDOT) conductive polymer in various organic solvents. For this purpose, the polymerization of 3,4-ethylenedioxythiophene (EDOT) monomer was carried out in three different organic solvents, ethanol, 1-butanol and acetonitrile with two commonly used oxidants, ferric (III) chloride (FeCl3) and ferric (III) p-toluenesulfonate (FepTS). In this regard, the oxidant and monomer solutions with variable molar concentrations (0.25, 0.5, 1.0 M) were prepared in particular solvents and then these solutions were mixed with different monomer/oxidant volume ratios. The obtained dispersions of PEDOT can readily be polymerized on the surface of different materials after solvent evaporation and a uniform film can be achieved. The effect of molar as well as volume concentrations of EDOT monomer and oxidant on insulating (undoped/neutral) and film forming properties of PEDOT was investigated. These dispersions were applied on a transparent PET film and cellulosic fibers (viscose), dried at room temperature and analyzed using scanning electron microscope (SEM), optical microscope and ATR-FTIR spectroscopic analysis. The electrical characterization of undoped PEDOT-coated fibers was performed on Keithly picoammeter. This study contributes to obtain a simpler and instantaneous polymerization method of PEDOT preparation and to enhance its application area.

  • 20.
    Bashir, Tariq
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Fast, Lars
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Persson, Nils-Krister
    Högskolan i Borås, Institutionen Textilhögskolan.
    Electrical Resistance Measurement Methods and Electrical Characterization of Poly(3,4-ethylenedioxythiophene)- Coated Conductive Fibers2012Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 124, nr 4, s. 2954-2961Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Textile fibers and yarns of high conductivity, and their integration into wearable textiles for different electronic applications, have become an important research field for many research groups throughout the world. We have produced novel electrically conductive textile yarns by vapor-phase polymerization (VPP) of a conjugated polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), on the surface of commercially available textile yarns (viscose). In this article, we have presented a novel setup for electrical resistance measurements, which can be used not only for fibrous structures but also for woven structures of specific dimensions. We have reported a two-point resistance- measuring method using an already manufactured setup and also a comparison with the conventionally used method (so-called crocodile clip method). We found that the electrical properties of PEDOT-coated viscose fibers strongly depend on the concentration of oxidant (FeCl3)and the doping (oxidation) process of PEDOT. To evaluate the results, we used mass specific resistance values of PEDOT-coated viscose yarns instead of normal surface resistance values. The voltage–current (V–I) characteristics support the ohmic behavior of coated fibers to some extent. Monitoring of the charging effect of the flow of current through conductive fibers for prolonged periods of time showed that conductivity remains constant. The change in electrical resistance values with increase in the length of coated fibers was also reported. The resistance measuring setup employed could also be used for continuous measurement of resistance in the production of conductive fibers, as well as for four-point resistance measurement.

  • 21.
    Bashir, Tariq
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Naeem, Jawad
    Persson, Nils-Krister
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    FUNCTIONAL TEXTILES: Micro-porous Conductive Membranes for Bio-fuel Cell and Anti-static Air Filter Applications2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Conductive membranes are the highly demanding materials in the field of bio-fuel generation, bio-electrodes, sensors and anti-static air filter systems. The conductive membranes can effectively be utilized for above mentioned applications if they have better conductivity, lower weight, flexibility and cost effectiveness. Textile materials are extremely versatile in nature because their synergic combinations with other functional materials could be used for a wide range of applications, such as medical, sports, defence, energy generation and chemical industry. The non-woven micro-porous textile substrates can effectively be functionalized by coating them with conjugated polymers, such as PEDOT and polypyrrole. Coating with conjugated polymers not only gives better conductivity values but also maintain the lower molecular weight of the substrate material. In our research, we have prepared micro-porous conductive membranes by coating cellulosic non-woven fabrics with conductive polymer PEDOT. For coating purpose, we utilized most effective deposition technique, which is called chemical vapour deposition (CVD) process. The deposition of PEDOT by CVD process showed advantages over other conventionally used methods, such as the micro-pores were not blocked even after PEDOT deposition. The electrical characterization on produced conductive membranes was performed by using Kiethely 6000 picoammeter. The surface morphology was examined by scanning electron microscopy and structural properties were determined by ATR-FTIR analysis. In order to see the behaviour of these conductive membranes, electrochemical impedance scanning (EIS) was performed in different electrolyte solutions. The produced conductive membranes might have potential to be utilized as active electrode in bio-fuel cells and also can be used in anti-static air filter systems.

  • 22.
    Bashir, Tariq
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Naeem, Jawad
    Persson, Nils-Krister
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Functionalization of Textile Materials by Coating with Conjugated Polymers2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    During the last decade, smart textiles have attracted an enormous attention of researchers and found extraordinary applications in biomedical, sports, defense, energy, and fashion industry. These textiles are able to accept the physical signals from external stimuli and then generate a reaction in the form of thermal, electrical, chemical and magnetic signals. They should be in the form of functionalized fabric or electro-active fibers. A numerous techniques for the production of electrically conductive fibers have already been developed. In this study, we have prepared relatively highly conductive fibers with better mechanical properties. For this purpose, we have functionalized the commercially available textile fibers by coating with intrinsically conductive polymer (ICP), poly(3,4-ethylenedioxythiophene) (PEDOT). An efficient coating technique, so called oxidative chemical vapor deposition (CVD) was utilized for making uniform, thin and highly conductive polymer layers on the surface of textile fibers. For our initial experiments, we used viscose and polyester fibers as substrate materials. After performing a series of experiments, we have optimized a number of reaction parameters at which good electro-mechanical properties of conductive fibers can be achieved. At specific reaction conditions, the conductivity level which we have attained is approximately 15 S/cm. The PEDOT coated viscose and polyester fibers were compared in order to find out the best suitable substrate material. For increasing the service life of obtained conductive fibers, a thin layer of silicon resin was applied on the surface of PEDOT coated fibers.

  • 23.
    Bashir, Tariq
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Persson, Nils-Krister
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Smart Textiles: A novel concept of functionalizing textile materials2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Electrically conductive textile materials are the key components in smart and interactive textile applications. In our research, we introduced functionalities in commercially available textile substrates (fibers and fabrics) by coating them with conjugated polymer, such as poly (3,4-ethylenedioxythiophene) (PEDOT) [1-2]. In order to get conductivities that are of use, an efficient technique, chemical vapor deposition (CVD), was used. The obtained coated fibers and fabrics exhibited good electro-mechanical properties and can be utilized for a number of electronic applications, such as stretch sensors, anti-static air filters and electrodes for bio-fuel cells.

  • 24.
    Bashir, Tariq
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Persson, Nils-Krister
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Production of conductive yarns by chemical vapour deposition technique of PEDOT viscose fibres2010Konferansepaper (Fagfellevurdert)
  • 25.
    Bashir, Tariq
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Persson, Nils-Krister
    [external].
    Production of PEDOT Coated Conductive Fibers for Smart & Interactive Textile Applications2012Konferansepaper (Fagfellevurdert)
  • 26.
    Bashir, Tariq
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Persson, Nils-Krister
    Surface Modification of Conductive PEDOT Coated Textile Yarns with Silicone Resin2011Inngår i: Materials technology (New York, N.Y.), ISSN 1066-7857, E-ISSN 1753-5557, Vol. 26, nr 3, s. 135-139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electroactive textile fibres and fabrics have been used in smart and interactive clothing for medical,military and sports applications. The improved surface properties of conductive textiles are required for their successful integration in all of the above mentioned applications. This paper presents the production of conductive poly(3,4-ethylenedioxythiophene) (PEDOT) coated viscose yarns in longer length, i.e. 5 m, and the surface modification of the coated yarns by treating with silicone solution. The structural properties of silicone coated conductive yarns were then investigated by Fourier transform infrared spectroscopy and thermogravimetric analysis. The effect of silicone coating on the mechanical, electrical and hydrophobic properties was also evaluated and then compared with the PEDOT coated viscose yarns without surface treatment. Results show that the mechanical and hydrophobic properties of conductive yarns were improved by surface modification with silicone without affecting their structural properties. The surface modified PEDOT coated yarns could be used as pressure and stretch sensors in health care applications.

  • 27.
    Bashir, Tariq
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ramamoorthy, Sunil Kumar
    Persson, Nils-Krister
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    All-organic conductive fibers for smart and interactive textile applications2013Konferansepaper (Annet vitenskapelig)
  • 28.
    Bazooyar, Faranak
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Bohlén, Martin
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Bolton, Kim
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Computational Studies of Water and Carbon Dioxide Interactions with Cellobiose2015Inngår i: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 21, s. 2553-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    B3LYP/6-311++G** with dispersion correction (DFT-D) was used to study local and global minimum energy structures of water (H2O) or carbon dioxide (CO2) bonding with a pair of cellobiose molecules. The calculations showed that neither the H2O nor the CO2 prefer to be between the cellobiose molecules, and that the minimum energy structures occur when these molecules bond to the outer surface of the cellobiose pair. The calculations also showed that the low energy structures have a larger number of inter-cellobiose hydrogen bonds than the high energy structures. These results indicate that penetration of H2O or CO2 between adjacent cellobiose pairs, which would assist steam or supercritical CO2 (SC-CO2) explosion of cellulose, is not energetically favored. Comparison of the energies obtained with DFT-D and DFT (the same method but without dispersion correction) show that both hydrogen bonds and van der Waals interactions play an important role in cellobiose-cellobiose interactions.

  • 29.
    Bazooyar, Faranak
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Molecular-level Simulations of Cellulose Dissolution by Steam and SC-CO2 Explosion2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Dissolution of cellulose is an important but tough step in biofuel production from lignocellulosic materials. Steam and supercritical carbon dioxide (SC-CO2) explosion are two effective methods for dissolution of some lignocellulosic materials. Loading and explosion are the major processes of these methods. Studies of these processes were performed using grand canonical Monte Carlo and molecular dynamics simulations at different pressure/ temperature conditions on the crystalline structure of cellulose. The COMPASS force field was used for both methods. The validity of the COMPASS force field for the calculations was confirmed by comparing the energy and structures obtained from molecular mechanics simulations of cellobiose (the repeat unit of cellulose), water–cellobiose, water-cellobiose pair and CO2-cellobiose pair systems with those obtained from first principle calculations with and without dispersion correction. A larger disruption of the cellulose crystal structure was seen during loading than that during the explosion process. This is seen by an increased separation of the cellulose chains from the centre of mass of the crystal during the initial stages of the loading, especially for chains in the outer shell of the crystalline structure. Reducing and non-reducing ends of the cellulose crystal show larger disruption than the central core; this leads to increasing susceptibility to enzymatic attack in these end regions. There was also change from the syn to the anti torsion angle conformations, especially for chains in the outer cellulose shell. Increasing the temperature increases the disruption of the crystalline structure during loading and explosion.

  • 30.
    Bazooyar, Faranak
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Bolton, Kim
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Molecular-level Simulations of Cellulose Steam Explosion2015Inngår i: Quantum Matter, ISSN 2164-7615, Vol. 4, nr 2, s. 115-122Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Grand canonical Monte Carlo and molecular dynamics simulations are used to study steam explosion of crystalline cellulose using 100, 160, 210 and 250 °C saturated steam. The simulations are based on the COMPASS force field, which provides a valid description of the cellulose crystal structure and water-cellobiose interactions. Disruption of the crystal structure during steaming is typically larger than that during the explosion stage and the restructuring is larger at increased temperature and pressure. This is seen by an increased separation of the cellulose chains from the center of mass of the crystal during the initial stages of the steaming, especially for chains in the outer shell of the elementary fibril. There is a large change in the radius of gyration and fraction of anti torsion angle conformers for chains in the outer shell of the elementary fibril. In addition, the disruption at the reducing and non-reducing ends of the cellulose crystal is larger than in the central core, increasing susceptibility to enzymatic attack in these end regions.

  • 31.
    Bazooyar, Faranak
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Momany, Frank A.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Validating Empirical Force Fields for Molecular-level Simulation of Cellulose Dissolution2012Inngår i: Computational and Theoretical Chemistry, ISSN 2210-271X, E-ISSN 2210-2728, Vol. 984, s. 119-127Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The calculations presented here, which include dynamics simulations using molecular mechanics forcefields and first principles studies, indicate that the COMPASS forcefield is preferred over the Dreiding and Universal forcefields for studying dissolution of large cellulose structures. The validity of these forcefields was assessed by comparing structures and energies of cellobiose, which is the shortest cellulose chain, obtained from the forcefields with those obtained from MP2 and DFT methods. In agreement with the first principles methods, COMPASS is the only forcefield of the three studied here that favors the anti form of cellobiose in the vacuum. This forcefield was also used to compare changes in energies when hydrating cellobiose with 1–4 water molecules. Although the COMPASS forcefield does not yield the change from anti to syn minimum energy structure when hydrating with more than two water molecules – as predicted by DFT – it does predict that the syn conformer is preferred when simulating cellobiose in bulk liquid water and at temperatures relevant to cellulosedissolution. This indicates that the COMPASS forcefield yields valid structures of cellulose under these conditions. Simulations based on the COMPASS forcefield show that, due to entropic effects, the syn form of cellobiose is energetically preferred at elevated temperature, both in vacuum and in bulk water. This is also in agreement with DFT calculations.

  • 32.
    Bohlén, Martin
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Conformational studies of poly(vinylidene fluoride), poly(trifluoroethylene) and poly(vinylidene fluoride-co-trifluoroethylene) using density functional theory2014Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, nr 25, s. 12929-12939Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Different conformations of systems consisting of poly(vinylidene fluoride) (PVDF), poly(trifluoroethylene) (PTrFE) and poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) were investigated using density functional theory with dispersion correction. It was found that the trans-gauche-trans-gauche´ (TGTG´) conformation of a single PVDF chain is the lowest energy conformer. Crystals of PVDF were modelled using between two to five chains with up to 12 repeat units in each chain and, in agreement with experiment, structures comprised partly or completely of chains with the TGTG´ conformation are more stable than structures built up from chains with all-trans (TTTT) conformation. This indicates that an all-trans segment or chain will not induce the growth of a larger crystal with the same chain conformations. In contrast, the energetically preferred structure of PTrFE chains is an all-trans (TTTT) conformation, and the results indicate that copolymerization of vinylidene fluoride with trifluoroethylene can facilitate the formation of the all-trans PVDF conformations. This is probably due to increased intramolecular repulsion between the fluorine atoms and an increased intermolecular attraction in the crystal structure.

  • 33.
    Bohlén, Martin
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Inducing the piezoelectric β-phase of PVDF: a DFT study2014Konferansepaper (Fagfellevurdert)
  • 34.
    Bohlén, Martin
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Inducing the β-phase of poly(vinylidene fluoride): a review2014Inngår i: Annual Review of Nanoscience and Nanotechnology, ISSN 2159-9688, Vol. 1, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Poly(vinylidene fluoride) (PVDF) is a versatile material with numerous applications in many fields of industry and science. The extent of applications, ranging from approved contact materials in the food industry to monitors for respiration and heart-rate in medicine, drives the research and development by the materials science community. The largest limiting factor when using PVDF in applications where its piezo- and pyroelectricity is important, is the amount of the highly polar crystalline β-phase in the material. PVDF is polymorphic and usually crystallizes from melt or solution into the non-polar α-phase, which is of little use in piezoelectric applications. Many studies have therefore aimed at increasing the amount of the β-phase crystal structure in the material. Cold drawing of α-phase PVDF, poling in high electric fields, copolymerization with trifluoroethylene, and inclusion of different types of additives to PVDF have been studied using both experimental and computational techniques. This review presents the current status and understanding of these processes, and summarizes results from previous studies. © Global Scientific Publishers 2015.

  • 35.
    Bohlén, Martin
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Satyanarayana, Kavitha Chelakara
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Computational Studies of Poly(vinylidene fluoride)-Single Wall Carbon Nanotube Systems2013Inngår i: Journal of Computational and Theoretical Nanoscience, ISSN 1546-1955, E-ISSN 1546-1963, Vol. 10, nr 6, s. 1317-1325Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    First principles and molecular mechanics methods have been used to study poly(vinylidene fluoride)—single wall carbon nanotube systems. First principles calculations (Møller-Plesset second order perturbation theory and density functional theory with B3LYP exchange correlation functional with and without dispersion correction) using short poly(vinylidene fluoride) segments and short hydrogen-capped single wall carbon nanotubes show that the polymer segments prefer to have the β-rather than the β-conformation both in the absence and presence of the single wall carbon nanotube. The lowest energy structure is obtained when the poly(vinylidene fluoride) has an β-conformation and is located parallel to the single wall carbon nanotube wall. In contrast to the Dreiding and Universal force fields, the COMPASS force field predicts the structures containing the β-conformation of poly(vinylidene fluoride) to be the lowest in energy in agreement with first principles results. The COMPASS force field was consequently used in preliminary studies of a longer poly(vinylidene fluoride) chain and a longer single wall carbon nanotube using molecular dynamics.

  • 36.
    Bohlén, Martin
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Yaghooby, Haleh
    Airola, Karri
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Film Extrusion of Hydroxyapapatite and β-Tricalciumphosphate Functionalized Polyactide Polymers for Biomedical Implants2010Konferansepaper (Annet vitenskapelig)
  • 37.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Modelling carbon nanotube growth2008Konferansepaper (Annet vitenskapelig)
  • 38.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Simulations of water, metal and carbon clustering2008Konferansepaper (Annet vitenskapelig)
  • 39.
    Bolton, Kim
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Börjesson, Anders
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Computational studies of single-walled carbon nanotube growth2011Inngår i: SNIC Progress Report (2008-2009), s. 40-46Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Allocation of time on the Swedish national supercomputing facilities since 2000, as well as support from other sources, has allowed us to perform computational studies on a wide variety of systems. These include properties and growth of carbon nanotubes [1–36], icecatalysed reactions of importance to stratospheric ozone depletion[37], calculations of vapour-liquid, liquid-liquid and vapour-liquid-liquid phase equilibrium of single, binary and ternary component systems[38], and, more recently, carbonaceous polymer nanocomposites and cellulose decomposition. More details of these projects are available at the web page given above.

  • 40.
    Bolton, Kim
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    De Mena, Barbara
    ttz Bremerhaven.
    Schories, Gerhard
    ttz Bremerhaven.
    Sustainable Management of Solid Waste2016Inngår i: Resource Recovery to approach zero municipal wastes / [ed] M. J. Taherzadeh and T. Richards, CRC Press, 2016, s. 23-41Kapittel i bok, del av antologi (Fagfellevurdert)
  • 41.
    Bolton, Kim
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ding, F.
    Börjesson, Arne
    Zhu, W.M.
    Duan, H.M.
    Harutyunyan, A.R.
    Curtarlo, S.
    Computational Studies of Catalytic Particles for Carbon Nanotube Growth2009Inngår i: Journal of Computational and Theoretical Nanoscience, ISSN 1546-1955, E-ISSN 1546-1963, Vol. 6, nr 1, s. 1-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We review our computational studies of the melting temperatures and mechanisms of iron and iron-carbide clusters. Both isolated and supported clusters have been considered, and substrates with different shapes or pores have been simulated. It has been seen, for example, that the surface curvature—or local surface curvature—of the particle plays a dominant role in the melting mechanism and temperature. It has also been observed that the melting mechanism for small clusters is different to that of larger clusters.

  • 42.
    Bolton, Kim
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Zhu, Wuming
    Börjesson, Anders
    Progress in understanding controlled single-wall carbon nanotube growth from computer simulations2012Inngår i: Journal of Computational and Theoretical Nanoscience, ISSN 1546-1955, E-ISSN 1546-1963, Vol. 9, nr 6, s. 819-825Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Density functional theory based on the PW91 and PBE exchange-correlation functionals was used to study processes that are expected to play a key role in single-walled carbon nanotube (SWNT) growth and continued growth. It is shown that Ni clusters adapt their shape to the shape of the SWNT end to which they are attached. The results also show that the presence of SWNTs affects Ostwald ripening of the catalyst metal clusters and that, under certain conditions, the net diffusion may be from larger to smaller clusters. Also, Ostwald ripening may affect the chiral distribution of the SWNTs.

  • 43.
    Börjesson, A.
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Zhu, W.
    Amara, H.
    Bichara, C.
    Ducastelle, F.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Theoretical investigation of the Nanotube-metal junction2008Konferansepaper (Annet vitenskapelig)
  • 44.
    Börjesson, Anders
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Computational Studies of Metal Clusters and Carbon Nanotubes2008Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Carbon nanotubes constitute a promising candidate material in the realisation of nanoscaled electronics. This requires the ability for systematic production of carbon nanotubes with certain properties. This is called selective carbon nanotube growth. Two important aspects related to carbon nanotube growth are investigated in order to shed some light on this issue. First the melting behaviour of nanometer sized iron particles is investigated using molec- ular dynamics simulations. The iron nanoparticles studied are mounted on a porous Al2 O3 substrate in order to mimic the experimental situation during nanotube growth with the chemical vapour deposition method. This showed that the melting temperature of a cluster on a porous substrate may be lower than the melting temperature of a cluster on a flat sub- strate. This means that the catalyst particles used for nanotube growth may be liquid. In association with these studies the role of surface curvature to melting behaviour is explored further. The second presented study concerns the docking of nickel clusters to open single wall carbon nanotube ends. The motivation for this study was the possibility to continue growth of a carbon nanotube by docking of catalyst particles to its end. This work may also be of importance for the creation of electric junctions between carbon nanotubes and metal elec- trodes. This study showed that independent of whether the metal was gently put on the nanotube end or brutally forced to the end, it is the metal that adapts to the nanotube and not vice versa. For forced docking it was seen that carbon might dissolve in to the metal. This was not seen for the gently docked clusters. Carbon dissolution might affect the electronic properties of the metal (carbide) and nanotube-metal junction.

  • 45.
    Börjesson, Anders
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    First Principles Studies of the Effect of Nickel Carbide Catalyst Composition on Carbon Nanotube Growth2010Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, nr 42, s. 18045-18050Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Density functional theory calculations were used to investigate the stability of single-walled carbon nanotubes (CNTs) attached to nanoparticles. The total energies and the adhesion energies between the CNTs and the nanoparticles were calculated for systems where the nanoparticles were either pure Ni or Ni carbide. It was found that the adhesion between the CNT and a pure Ni cluster is stronger than between the same CNT and a Ni carbide cluster although the energy difference was small compared to the total adhesion energies. This adhesion strength implies that CNTs are likely to remain attached to both pure Ni and Ni carbide clusters and that either pure Ni or Ni carbide clusters may be docked onto the open CNT ends to achieve continued growth or electronic contacts between CNTs and electrode materials. The system with a CNT attached to a pure Ni cluster was found to be energetically favored compared to a system containing the same CNT attached to a Ni carbide. The difference in total energy implies that a CNT should act as a sink for C atoms dissolved in the Ni carbide cluster, which means that the dissolved C atoms will be drained from the cluster, yielding a pure metal in the zero Kelvin thermodynamic limit. It is argued that this draining procedure is likely to occur even if carbon is added to the cluster at a proper rate, for example, during CNT growth.

  • 46.
    Börjesson, Anders
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan. Högskolan i Borås, Institutionen Textilhögskolan.
    Modelling of Ostwald ripening of metal clusters attached to carbon nanotubes2011Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, nr 50, s. 24454-24462Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a model of Ostwald ripening of nanosized clusters and apply it to study the time evolution of metal particles attached to carbon nanotubes. The Ostwald ripening of metal clusters attached to carbon nanotubes differs from that of free metal clusters. While free clusters experience a rapid broadening in the size dispersion, this may be delayed by the nanotubes, which may therefore limit the ripening. The diameter and chirality of the carbon nanotubes were also seen to affect the Ostwald ripening of the catalyst particles. For a collection of carbon nanotubes that contains different diameters and chiralities, the clusters attached to carbon nanotubes with large diameters and strong carbon–metal adhesion are the most likely to survive the Ostwald ripening.

  • 47.
    Börjesson, Anders
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Erdtman, Edvin
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ahlström, Peter
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Berlin, Mikael
    Andersson, Thorbjörn
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Molecular modelling of oxygen and water permeation in polyethylene2013Inngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 54, nr 12, s. 2988-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Monte Carlo and molecular dynamics simulations were performed to calculate solubility, S, and diffusion, D, coefficients of oxygen and water in polyethylene, and to obtain a molecular-level understanding of the diffusion mechanism. The permeation coefficient, P, was calculated from the product of S and D. The AMBER force field, which yields the correct polymer densities under the conditions studied, was used for the simulations, and it was observed that the results were not sensitive to the inclusion of atomic charges in the force field. The simulated S for oxygen and water are higher and lower than experimental data, respectively. The calculated diffusion coefficients are in good agreement with experimental data. Possible reasons for the discrepancy in the simulated and experimental solubilities, which results in discrepancies in the permeation coefficients, are discussed. The diffusion of both penetrants occurs mainly by large amplitude, infrequent jumps of the molecules through the polymer matrix.

  • 48.
    Börjesson, Anders
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Harutyunyan, Avetik R.
    Curtarolo, Stefano
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Computational study of the thermal behavior of iron clusters on a porous substrate2008Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 77, nr 11Artikkel i tidsskrift (Fagfellevurdert)
  • 49.
    Börjesson, Anders
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Zhu, Wuming
    Amara, Hakim
    Bichara, Christophe
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Computational studies of metal-carbon nanotube interfaces for regrowth and electronic transport2009Inngår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 9, nr 3, s. 1117-1120Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    First principles and tight binding Monte Carlo simulations show that junctions between single-walled carbon nanotubes (SWNTs) and nickel clusters are on the cluster surface, and not at subsurface sites, irrespective of the nanotube chirality, temperature, and whether the docking is gentle or forced. Gentle docking helps to preserve the pristine structure of the SWNT at the metal interface, whereas forced docking may partially dissolve the SWNT in the cluster. This is important for SWNT-based electronics and SWNT-seeded regrowth.

  • 50. Chalapati, Sachin
    et al.
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Toluene mediated fluid catalytic cracking of low density polyethylene using ionic liquids2014Konferansepaper (Annet vitenskapelig)
1234 1 - 50 of 177
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf