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Johansson, Erik
Publications (10 of 10) Show all publications
Ahlström, P., Gebäck, T., Johansson, E. & Bolton, K. (2010). Water absorption in polymers. Paper presented at 8th European Conference on Computational Chemistry, 25-25.8, Lund. Paper presented at 8th European Conference on Computational Chemistry, 25-25.8, Lund.
Open this publication in new window or tab >>Water absorption in polymers
2010 (English)Conference paper, Poster (with or without abstract) (Other academic)
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).

Keywords
Resursåtervinning, Computational modelling
National Category
Theoretical Chemistry Other Industrial Biotechnology
Identifiers
urn:nbn:se:hb:diva-6524 (URN)2320/7484 (Local ID)2320/7484 (Archive number)2320/7484 (OAI)
Conference
8th European Conference on Computational Chemistry, 25-25.8, Lund
Available from: 2015-12-22 Created: 2015-12-22
Bolton, K., Johansson, E., Jönsson, L. & Ahlström, P. (2009). Simulation of water clusters in vapour, alkanes and polyethylenes. Molecular Simulation, 35(10/11), 888-896
Open this publication in new window or tab >>Simulation of water clusters in vapour, alkanes and polyethylenes
2009 (Swedish)In: Molecular Simulation, ISSN 0892-7022, E-ISSN 1029-0435, Vol. 35, no 10/11, p. 888-896Article in journal (Refereed) Published
Abstract [en]

The Gibbs Ensemble Monte Carlo (GEMC) technique has been used to study the clustering of water in vapour, alkanes and polyethylene, where the water clusters are in equilibrium with liquid phase water. The effect of an external electric field and ionic impurities on the clustering of water in the hydrocarbons (alkanes and polyethylene) has also been studied. The simulations of water clustering in polyethylene were made more efficient by using a connectivity altering osmotic Gibbs ensemble method. It was found that trends in the size distribution of water clusters in the hydrocarbons are similar to those found in the pure vapour, but that fewer and smaller clusters are formed as the length of the hydrocarbon chain increased. Also, large external electric fields decrease the solubility of water in hydrocarbons, whereas the presence of ionic species dramatically increases the solubility.

Place, publisher, year, edition, pages
Taylor & Francis Ltd., 2009
Keywords
Energi och material
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hb:diva-3097 (URN)10.1080/08927020902787804 (DOI)2320/8067 (Local ID)2320/8067 (Archive number)2320/8067 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-11-24Bibliographically approved
Johansson, E., Ahlström, P. & Bolton, K. (2008). Molecular simulation of the effect of ionic impurities and external electric fields on rod-like water clusters in polyethylene. Polymer, 49(24), 5357-5362
Open this publication in new window or tab >>Molecular simulation of the effect of ionic impurities and external electric fields on rod-like water clusters in polyethylene
2008 (English)In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 49, no 24, p. 5357-5362Article in journal (Refereed) Published
Abstract [en]

Monte Carlo methods have been combined with end-bridging methods to study the solubility and structure of water in polyethylene, where the polyethylene contains a pair of oppositely charged ionic impurities. The water in the polymer is in equilibrium with pure liquid water. Both the polymer and pure water phases are exposed to an external electric field. The ions dramatically increase the solubility of water in polyethylene and induce the formation of a stable, rod-like water cluster between the ions. The solubility, the hydrogen-bond ordering of the water molecules in the cluster and the size of the cluster increase in the presence of an external field that enhances the local electric field between the ions. When the direction of the external field is reversed, and when it has the same magnitude as the local ionic field, the rod-like structure is broken up and a smaller cluster forms around each ion. (C) 2008 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
Elsevier Ltd, 2008
Keywords
polymerer, datormodellering, vatten, Energi och material
National Category
Materials Chemistry
Identifiers
urn:nbn:se:hb:diva-2549 (URN)10.1016/j.polymer.2008.09.052 (DOI)2320/4503 (Local ID)2320/4503 (Archive number)2320/4503 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-01Bibliographically approved
Johansson, E., Bolton, K. & Ahlström, P. (2008). On Polyethylene Cable Failure, Electric Fields, Water Clusters and Ions. In: (Ed.), Proceedings of the 100th Annual Meeting of the American Institute for Chemical Engineering: .
Open this publication in new window or tab >>On Polyethylene Cable Failure, Electric Fields, Water Clusters and Ions
2008 (English)In: Proceedings of the 100th Annual Meeting of the American Institute for Chemical Engineering, 2008Conference paper, Published paper (Refereed)
Keywords
polythylene cables, water trees, monte carlo, gibbs ensemble, simulations, Energi och material
National Category
Other Materials Engineering Physical Chemistry
Identifiers
urn:nbn:se:hb:diva-6058 (URN)2320/4426 (Local ID)2320/4426 (Archive number)2320/4426 (OAI)
Available from: 2015-12-22 Created: 2015-12-22
Johansson, E., Bolton, K. & Ahlström, P. (2008). Simulations of Water Clustering in Vapour, Hydrocarbons and Polymers. In: : . Paper presented at CHPC National Meeting, Durban, South Africa, December 9-10, 2008.
Open this publication in new window or tab >>Simulations of Water Clustering in Vapour, Hydrocarbons and Polymers
2008 (English)Conference paper, Published paper (Other academic)
Keywords
datormodellering, Energi och material
National Category
Materials Chemistry
Identifiers
urn:nbn:se:hb:diva-6084 (URN)2320/4538 (Local ID)2320/4538 (Archive number)2320/4538 (OAI)
Conference
CHPC National Meeting, Durban, South Africa, December 9-10, 2008
Available from: 2015-12-22 Created: 2015-12-22 Last updated: 2017-09-28Bibliographically approved
Johansson, E., Bolton, K., Theodorou, D. N. & Ahlström, P. (2007). Formation of rodlike structure of water between oppositely charged ions in decane and polyethylene. Journal of Chemical Physics, 127(19)
Open this publication in new window or tab >>Formation of rodlike structure of water between oppositely charged ions in decane and polyethylene
2007 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 127, no 19Article in journal (Refereed) Published
Place, publisher, year, edition, pages
American Institute of Physics, 2007
Keywords
alkanes, ions, water, gibbs ensemble, Energi och material
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hb:diva-2298 (URN)10.1063/1.2811721 (DOI)2320/2965 (Local ID)2320/2965 (Archive number)2320/2965 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-03Bibliographically approved
Johansson, E., Bolton, K., Theodorou, D. N. & Ahlström, P. (2007). Monte Carlo simulations of equilibrium solubilities and structure of water in n-alkanes and polyethylene. Journal of Chemical Physics, 126(22)
Open this publication in new window or tab >>Monte Carlo simulations of equilibrium solubilities and structure of water in n-alkanes and polyethylene
2007 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 126, no 22Article in journal (Refereed) Published
Place, publisher, year, edition, pages
American Institute of Physics, 2007
Keywords
monte carlo, modelering kolnanorör, Energi och material
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hb:diva-2300 (URN)10.1063/1.2745296 (DOI)2320/2967 (Local ID)224902 (ISBN)2320/2967 (Archive number)2320/2967 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-03Bibliographically approved
Johansson, E. (2007). Simulations of water clustering in vapour, hydrocarbons and polymers. (Doctoral dissertation). Chalmers tekniska högskola
Open this publication in new window or tab >>Simulations of water clustering in vapour, hydrocarbons and polymers
2007 (English)Doctoral thesis, monograph (Other academic)
Abstract [en]

It is commonly known that water plays a crucial role in many natural and industrial processes. One of these processes is the formation of water trees, and the subsequent breakdown of polyethylene used for high voltage cable insulation purposes. It has been shown that the mechanism for water molecules diffusing through amorphous polyethylene includes the formation of small water clusters. Gibbs Ensemble Monte Carlo molecular simulations has been performed to study the clustering of vapour phase water under vapour - liquid equilibrium conditions at temperatures ranging from 300 K to 600 K. The increase in vapour density with increasing temperature leads to a radical increase in the fraction of molecules belonging to clusters with two or more water molecules. It is also seen that the size of the clusters increases with temperature. The topologies of the smaller clusters, up to pentamers, have also been studied. A structural transition is observed from a large percentage with cyclic topology, which is the minimum energy configuration, at lower temperatures to predominantly linear clusters, favoured by entropic effects, at higher temperatures. Similar water properties have been obseved in simulations where the vapour phase has been replaced with a hydrocarbon rich phase ( n-alkanes and polyethylene ). Application of an external electric field to the polymer system reduces the water solubility and affects the water structure. A dramatic increase in water solubility in the hydrocarbon phase is observed when two oppositely charged ions are introduced in the hydrocarbon. The structure of the water have changed from several small clusters to a single large cluster with a rod-like shape. The cluster is extremely stable during the simulation. Application of an external electric field may enhance or reduce the effect of the ions depending on the direction of the field. Based on these observations is an alternative mechanism for water tree propagation proposed.

Place, publisher, year, edition, pages
Chalmers tekniska högskola, 2007
Series
Ny serie ; 2676
Keywords
cluster, gibbs ensemble, monte carlo, water, polyethylene, external field, ions, Energi och material
National Category
Physical Chemistry
Identifiers
urn:nbn:se:hb:diva-3436 (URN)2320/2617 (Local ID)978-91-7291-995-2 (ISBN)2320/2617 (Archive number)2320/2617 (OAI)
Available from: 2015-12-04 Created: 2015-12-04
Johansson, E., Bolton, K. & Ahlström, P. (2007). Water absorption in polyethylene under external electric fields. Journal of Chemical Physics, 127(2)
Open this publication in new window or tab >>Water absorption in polyethylene under external electric fields
2007 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 127, no 2Article in journal (Refereed) Published
Place, publisher, year, edition, pages
American Institute of Physics, 2007
Keywords
modelering, monte carlo, polymerer, Energi och material
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hb:diva-2299 (URN)10.1063/1.2750340 (DOI)2320/2966 (Local ID)024902 (ISBN)2320/2966 (Archive number)2320/2966 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-03Bibliographically approved
Johansson, E. & Ahlström, P. (2006). Atomistic Simulation Studies of Polymers and Water. In: : . Paper presented at 8th International Workshop on Applied Parallel Computing (PARA 2006), Umeå 18-21 juni 2006..
Open this publication in new window or tab >>Atomistic Simulation Studies of Polymers and Water
2006 (English)Conference paper, Published paper (Refereed)
Abstract [en]

A Monte Carlo simulation study of water and hydrocarbons aiming at understanding the degradation of polyethylene cable insulation is presented. The equilibrium distributions and clustering of water in vapour and in hydrocarbons was investigated using Gibbs ensemble Monte-Carlo simulations. Different combinations of water and hydrocarbon models are investigated in order to reproduce experimental densities of water and hydrocarbons in both the water phase and the hydrocarbon phase.

Keywords
alkanes, water, gibbs ensemble, Energi och material
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hb:diva-5770 (URN)10.1007/978-3-540-75755-9_7 (DOI)2320/3062 (Local ID)2320/3062 (Archive number)2320/3062 (OAI)
Conference
8th International Workshop on Applied Parallel Computing (PARA 2006), Umeå 18-21 juni 2006.
Available from: 2015-12-22 Created: 2015-12-22 Last updated: 2017-09-27Bibliographically approved
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