27 Janvier – Thesis defense - Valentin Makomra
14 h ENSAM Bordeaux - Building P. 031
Modelling the drying behaviour of green glue plywood.
The forests of the Congo Basin constitute an essential treasure for the well-being of humanity. However, they are poorly managed because to the intensive and highly selective cutting of a limited number of species. The objective of this thesis is to develop plywood panels glued in the green state of new tropical species. The expanding potential that technology promises could contribute to more sustainable management. Kiln-dried veneers before glueing in manufacture of plywood cause several damages (cracks, deformations), limiting the use of many species. The suggested solution is to glue them in the green state using a polyurethane adhesive before drying while holding them together by assembly. In this perspective, a multi-criteria analysis made it possible to prioritize the choices of interesting species to be exploited and valorized. A numerical modeling of the plywood of Bété (Mansonia altissima), made of three layers of veneer, glued in the green state and dried under atmospheric conditions, is carried out and feet experimentally. This allowed to better analyze and understand the various multi-physical phenomena and optimize drying. The development of this work was made with vacuum drying technology, with humidification cycles to relax stresses due to the preferential shrinkage between glued plies. Four original species was tested in standard conditions. Results feet all the minimum of standards requirements for commercialization. The most relevant results concerns species of Bete and Dabema, which are available to be valorized in the industry by this new technology.