1. Institute of Mathematics, Physics and Chemistry, Opole University of Technology, Luboszycka 5, 45-036 Opole, Poland, Institute of Coal Chemistry, Polish Academy of Sciences, Sowinskiego 5, 44-121 Gliwice, Poland, and Department of Physical Chemistry and Technology of Polymers, Faculty of Chemistry, Silesian University of Technology, Strzody 9, 44-100 Gliwice, Poland