Ändra sökning
Avgränsa sökresultatet
1 - 13 av 13
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • harvard-cite-them-right
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Svensson, Sofie
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Åkesson, Dan
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Bohlén, Martin
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Reprocessing of High-Density Polyethylene Reinforced with Carbon Nanotubes2020Ingår i: Journal of Polymers and the Environment, ISSN 1566-2543, E-ISSN 1572-8919, Vol. 28, nr 7, s. 1967-1973Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-density polyethylene (HDPE) was compounded with 3 wt% carbon nanotubes (CNTs). In order to simulate mechanical recycling, both the nanocomposite and neat HDPE were repeatedly extruded and subsequently analysed by tensile tests, Charpy impact strength, differential scanning calorimetry (DSC), oxidation induction time (OIT), Gel Performance Chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR) and TEM After 10 cycles of extrusion, thermal, mechanical, and rheological tests did not reveal any significant degradation. In order to better study the effect of the CNTs, a large number of cycles were simulated by processing the materials for up to 200 min. After 200 min of processing, the neat HDPE was significantly degraded whereas the nanocomposite was almost unaffected.

  • 2.
    Erdtman, Edvin
    et al.
    Linköping Universitet.
    Bohlén, Martin
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Ahlström, Peter
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Gkourmpis, Thomas
    Borealis AB.
    Berlin, Mikael
    Tetra Pak Packaging Solutions AB.
    Andersson, Thorbjörn
    Tetra Pak Packaging Solutions AB.
    Bolton, Kim
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    A molecular-level computational study of the diffusion and solubility of water and oxygen in carbonaceous polyethylene nanocomposites2016Ingår i: Journal of Polymer Science Part B: Polymer Physics, ISSN 0887-6266, E-ISSN 1099-0488, Vol. 54, s. 589-602Artikel i tidskrift (Refereegranskat)
    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. 

  • 3.
    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 Cellobiose2015Ingår i: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 21, s. 2553-Artikel i tidskrift (Refereegranskat)
    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.

  • 4.
    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 theory2014Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, nr 25, s. 12929-12939Artikel i tidskrift (Refereegranskat)
    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.

  • 5.
    Bohlén, Martin
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Effect of single wall carbon nanotubes on the conformation of Poly(vinylidene fluoride)2014Ingår i: Quantum Matter, ISSN 2164-7615, Vol. 3, nr 4, s. 339-343Artikel i tidskrift (Refereegranskat)
    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.

  • 6.
    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 study2014Konferensbidrag (Refereegranskat)
  • 7.
    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 review2014Ingår i: Annual Review of Nanoscience and Nanotechnology, ISSN 2159-9688, Vol. 1, nr 1Artikel i tidskrift (Refereegranskat)
    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.

  • 8. Haghighatpanah, Shayesteh
    et al.
    Bohlén, Martin
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Molecular level computational studies of polyethylene and polyacrylonitrile composites containing single walled carbon nanotubes: effect of carboxylic acid functionalization on nanotube-polymer interfacial properties2014Ingår i: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 2, nr 74Artikel i tidskrift (Refereegranskat)
    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.

  • 9. Erdtman, Edvin
    et al.
    Bohlén, Martin
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ahlström, Peter
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Gkourmpis, Thomas
    Berlin, Mikael
    Andersson, Thorbjörn
    Bolton Kim, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Permeation of water and oxygen through carbonaceous PE composites2014Konferensbidrag (Refereegranskat)
  • 10.
    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 Systems2013Ingår i: Journal of Computational and Theoretical Nanoscience, ISSN 1546-1955, E-ISSN 1546-1963, Vol. 10, nr 6, s. 1317-1325Artikel i tidskrift (Refereegranskat)
    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.

  • 11.
    Bohlén, Martin
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Molecular Dynamics Studies of the Influence of Single Wall Carbon Nanotubes on the Mechanical Properties of Poly(vinylidene fluoride)2013Ingår i: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 68, s. 73-80Artikel i tidskrift (Refereegranskat)
    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.

  • 12. Chelakara Satyanarayana, Kavitha
    et al.
    Bohlén, Martin
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Lund, Anja
    Rychwalski, Rodney
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Analysis of the torsion angle distribution of poly(vinylidene fluoride) in the melt2012Ingår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 53, nr 4, s. 1109-1114Artikel i tidskrift (Refereegranskat)
    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.

  • 13.
    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 Implants2010Konferensbidrag (Övrigt vetenskapligt)
1 - 13 av 13
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • harvard-cite-them-right
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf