Change search
Refine search result
1 - 12 of 12
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Bazooyar, Faranak
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bohlén, Martin
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bolton, Kim
    University of Borås, Faculty of Textiles, Engineering and Business.
    Computational Studies of Water and Carbon Dioxide Interactions with Cellobiose2015In: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 21, p. 2553-Article in journal (Refereed)
    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.

  • 2.
    Bohlén, Martin
    et al.
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    Conformational studies of poly(vinylidene fluoride), poly(trifluoroethylene) and poly(vinylidene fluoride-co-trifluoroethylene) using density functional theory2014In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 25, p. 12929-12939Article in journal (Refereed)
    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.

  • 3.
    Bohlén, Martin
    et al.
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    Effect of single wall carbon nanotubes on the conformation of Poly(vinylidene fluoride)2014In: Quantum Matter, ISSN 2164-7615, Vol. 3, no 4, p. 339-343Article in journal (Refereed)
    Abstract [en]

    Structures consisting of single Poly(vinylidene fluoride) (PVDF) chains, single wall carbon nanotubes (SWCNTs), a PVDF chain interacting with a SWCNT and of five PVDF chains arranged to resemble the α and β crystal structures of PVDF were evaluated using geometry optimizations and single point energy calculations. Density functional theory with dispersion correction was used for all calculations. The conformer of PVDF is the lowest energy structure, irrespective of whether the SWCNT is present or not. Interaction with the SWCNT reduces the energy difference between the β and α conformers by approximately 30%, indicating that SWCNTs can increase the relative amount of the β conformers at higher temperatures. However, even in the presence of the SWCNT this energy difference is approximately 1.67 kcal/mol per –CH2CF2– repeat unit, which is larger than kT at 300 K (0.6 kcal/mol). Hence, the presence of the SWCNTs is not expected to substantially increase the relative amount of the β conformers at these conditions. Compression of the α and β crystal structures, which occurs during fibre extrusion, and which may be increased if nanoparticles are present in the polymer matrix, further decreases the energy difference between the β and α conformers but only to a very small extent at pressures relevant to fibre extrusion.

  • 4.
    Bohlén, Martin
    et al.
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    Inducing the piezoelectric β-phase of PVDF: a DFT study2014Conference paper (Refereed)
  • 5.
    Bohlén, Martin
    et al.
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    Inducing the β-phase of poly(vinylidene fluoride): a review2014In: Annual Review of Nanoscience and Nanotechnology, ISSN 2159-9688, Vol. 1, no 1Article in journal (Refereed)
    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.

  • 6.
    Bohlén, Martin
    et al.
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    Molecular Dynamics Studies of the Influence of Single Wall Carbon Nanotubes on the Mechanical Properties of Poly(vinylidene fluoride)2013In: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 68, p. 73-80Article in journal (Refereed)
    Abstract [en]

    Molecular dynamics simulations and geometry optimizations based on the Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies (COMPASS) force field were performed to understand the effect of Single Wall Carbon Nanotubes (SWCNTs) on the mechanical properties of Poly(vinylidene fluoride) (PVDF). In particular, the Young’s modulus, bulk and shear modulus, pullout energy, pullout force, interfacial shear stress and interfacial bonding energy were calculated. The presence of the SWCNTs can increase the Young’s modulus of the systems studied here by 1 GPa in the direction of the SWCNT axis, although this depends on the distance between neighboring SWCNTs. The calculated interfacial shear stress was between 100 and 129 MPa, which is in agreement with results obtained for other SWCNT-polymer systems. The results, and in particular those obtained for the bulk and shear modulus, show that SWCNTs do not have a significant effect on the bulk mechanical properties. Functionalizing the SWCNTs may yield stronger adhesion between the nanotube and the polymer, thereby achieving improved mechanical properties. ⺠Computational studies using molecular dynamics and molecular mechanics. ⺠Effect of single wall carbon nanotubes on the mechanical properties of Poly(vinylidene fluoride). ⺠Alignment of the nanotubes plays a crucial role for the reinforcing effect. ⺠When aligned, an increase in Young’s modulus of approximately 1 GPa could be observed. ⺠The interfacial shear stress was calculated to be in the range of 100–129 MPa.

  • 7.
    Bohlén, Martin
    et al.
    University of Borås, School of Engineering.
    Satyanarayana, Kavitha Chelakara
    Bolton, Kim
    University of Borås, School of Engineering.
    Computational Studies of Poly(vinylidene fluoride)-Single Wall Carbon Nanotube Systems2013In: Journal of Computational and Theoretical Nanoscience, ISSN 1546-1955, E-ISSN 1546-1963, Vol. 10, no 6, p. 1317-1325Article in journal (Refereed)
    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.

  • 8.
    Bohlén, Martin
    et al.
    University of Borås, School of Engineering.
    Yaghooby, Haleh
    Airola, Karri
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Film Extrusion of Hydroxyapapatite and β-Tricalciumphosphate Functionalized Polyactide Polymers for Biomedical Implants2010Conference paper (Other academic)
  • 9. Chelakara Satyanarayana, Kavitha
    et al.
    Bohlén, Martin
    University of Borås, School of Engineering.
    Lund, Anja
    Rychwalski, Rodney
    Bolton, Kim
    University of Borås, School of Engineering.
    Analysis of the torsion angle distribution of poly(vinylidene fluoride) in the melt2012In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 53, no 4, p. 1109-1114Article in journal (Refereed)
    Abstract [en]

    Analysis of the torsionangledistribution of poly(vinylidene fluoride) (PVDF) structures at temperatures above its melting point is addressed by combining first principles methods, atomistic simulations and laboratory experiments. Amorphous, α- and β-conformations of PVDF structures have been considered. The results from the atomistic simulations as well as the experiments show that there is a larger probability of the PVDF torsions to be near ±180° at temperatures above the melting point, which is associated more with the β-conformation than the α-conformation.

  • 10.
    Erdtman, Edvin
    et al.
    Linköping Universitet.
    Bohlén, Martin
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ahlström, Peter
    University of Borås, Faculty of Textiles, Engineering and Business.
    Gkourmpis, Thomas
    Borealis AB.
    Berlin, Mikael
    Tetra Pak Packaging Solutions AB.
    Andersson, Thorbjörn
    Tetra Pak Packaging Solutions AB.
    Bolton, Kim
    University of Borås, Faculty of Textiles, Engineering and Business.
    A molecular-level computational study of the diffusion and solubility of water and oxygen in carbonaceous polyethylene nanocomposites2016In: Journal of Polymer Science Part B: Polymer Physics, ISSN 0887-6266, E-ISSN 1099-0488, Vol. 54, p. 589-602Article in journal (Refereed)
    Abstract [en]

    Monte Carlo and molecular dynamics simulations were performed to investigate the effect on the solubility, diffusion, and permeability of water and oxygen when adding graphene or single-walled carbon nanotubes (SWCNTs) to polyethylene (PE). When compared with pure PE, addition of graphene lowered the solubility of water, whereas at lower temperatures, the oxygen solubility increased because of the oxygen–graphene interaction. Addition of SWCNTs lowered the solubility of both water and oxygen when compared with pure PE. A detailed analysis showed that an ordered structure of PE is induced near the additive surface, which leads to a decrease in the diffusion coefficient of both penetrants in this region. The addition of graphene does not change the permeation coefficient of oxygen (in the direction parallel to the filler) and, in fact, may even increase this coefficient when compared with pure PE. In contrast, the water permeability is decreased when graphene is added to PE. The addition of SWCNTs decreases the permeability of both penetrants. Graphene can consequently be added to selectively increase the solubility and permeation of oxygen over water, at least at lower temperatures. 

  • 11. Erdtman, Edvin
    et al.
    Bohlén, Martin
    University of Borås, School of Engineering.
    Ahlström, Peter
    University of Borås, School of Engineering.
    Gkourmpis, Thomas
    Berlin, Mikael
    Andersson, Thorbjörn
    Bolton Kim, Kim
    University of Borås, School of Engineering.
    Permeation of water and oxygen through carbonaceous PE composites2014Conference paper (Refereed)
  • 12. Haghighatpanah, Shayesteh
    et al.
    Bohlén, Martin
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    Molecular level computational studies of polyethylene and polyacrylonitrile composites containing single walled carbon nanotubes: effect of carboxylic acid functionalization on nanotube-polymer interfacial properties2014In: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 2, no 74Article in journal (Refereed)
    Abstract [en]

    Molecular dynamics and molecular mechanics methods have been used to investigate additive – polymer interfacial properties in single walled carbon nanotube – polyethylene and single walled carbon nanotube – polyacrylonitrile composites. Properties such as the interfacial shear stress and bonding energy are similar for the two composites. In contrast, functionalizing the single walled carbon nanotubes with carboxylic acid groups leads to an increase in these properties, with a larger increase for the polar polyacrylonitrile composite. Increasing the percentage of carbon atoms that were functionalized from 1% to 5% also leads to an increase in the interfacial properties. In addition, the interfacial properties depend on the location of the functional groups on the single walled carbon nanotube wall.

1 - 12 of 12
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf