1. Polymer-Tribology Group, Division of Machine Elements, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Campus Porsön, 971 87 Luleå, Sweden
2. Laboratory for Tribology and Interface Nanotechnology, Faculty of Mechanical Engineering, University of Ljubljana, Bogišićeva 8, 1000 Ljubljana, Slovenia
3. Polymeric Composite Materials, Division of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Campus Porsön, 971 87 Luleå, Sweden