1. a Department of Polymer Engineering , University of Minho , Campus de Azurém, Guimarães, 4800-058, Portugal
2. b Department of Polymer Engineering , University of Minho , Campus de Azurém, Guimarães, 4800-058, Portugal
3. c Agrotechnological Research Institute , ATO, P.O. Box 17, AA Wageningen, NL-6700, The Netherlands