* Corresponding author. Address: Department of Rubber Technology,
Faculty of Science and Technology, University of Twente, P.O. Box 217,
7500 AE Enschede, The Netherlands. Tel.: C31 53 4892529; fax: C31 53
4893823.
E-mail address: j.w.m.noordermeer@utwente.nl (J.W.M. Noordermeer).