1. Department of Fiber and Polymer Technology; Wallenberg Wood Science Center; KTH Royal Institute of Technology; 100 44 Stockholm Sweden
2. ETH Zürich; Institute for Building Materials; Stefano-Franscini-Platz 3 8093 Zurich Switzerland
3. EMPA-Swiss Federal Laboratories for Material Testing and Research; Applied Wood Research Laboratory; Dübendorf 8600 Switzerland