The development of materials derived from biosourced products has been booming over the last decade. Due to this development, several projects have been launched in Europe. These projects are based particularly on the association of different natural products in order to obtain high added-value biocomposites, which represents a major economic and scientific challenge. However, only a few projects use by-products derived from agriculture. The development of new materials derived from these byproducts represents an important scientific challenge.
Recently, several national and European regulations, such as «Grenelle 2 de l'environnement» or the European directive 2002/91/CE, have been decided to promote the environmental quality of existing buildings owned by local governments, particularly with the recommendations on thermal insulation for these buildings, in order to reduce CO2 production (Law «Grenelle 1 article 4 et article 5-I» - Draft law «Grenelle 2 article 1 et article 2»).
One of these solutions is to use materials made from agricultural by-products thermal insulation of existing buildings.
The originality of this approach is the fact that it will use binders derived from natural biopolymers (polysaccharides) differently formulated, according to the desired properties. This strategy gives the possibility to distinguish this project from other current works aiming to blend plant fibres derived from agronomy with mineral binders.
Hence, a full range of biomaterials will be developed for thermal insulation of buildings. This approach is combined with environmental models in order to take into account the viability of these new materials in the long term and their industrial applications.
The insulating panels developed are composed of sunflower stems and a biosourced matrix (based on chitosan). The bark of the sunflower stems provides a mechanical function and the marrow gives the insulating panels good thermal properties. The developed insulator thus has a thermal diffusion coefficient l = 0.06 W.m-1.K-1. This value complies with the French regulation Thermal Regulation 2012.