1. Metallurgy and Materials Engineering Department and Laboratory of Food Chemistry, Katholieke Universiteit Leuven, B-3001 Heverlee, Belgium, Institute of Materials Science, University of Connecticut, 06269 Storrs, Connecticut, and Laboratoire de technologie des composites et polymères (LTC), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland