1. Poznan University of Technology, Institute of Materials Technology, Polymer Division; Piotrowo, 3 Poznan 61-138 Poland
2. Centre for Advanced Technologies, Adam Mickiewicz University; Umultowska, 89 C Poznan 61-614 Poland
3. Consiglio Nazionale Delle Ricerche, Istituto per I Polimeri, Compositi E Biomateriali, c/o Comprensorio Olivetti; via Campi Flegrei, 34 Pozzuoli NA 80078 Italy