Yan, Libo, Technische Universität Braunschweig, Department of Organic and Wood-Based Construction Materials, Hopfengarten 20, 38102 Braunschweig, Germany; Fraunhofer WilhelmKlauditz-Institut, Center for Light and Environmentally friendly Structures, Bienroder Weg 54E, 38108 Braunschweig, Germany, Germany