Fully Biobased Panels for Building Thermal Insulation

Sunflower plants grow in abundance in southwestern France. In addition to their wide availability, the sunflower pith particles stand out thanks to their alveolar structure and their particle porosity. Indeed, sunflower pith particles differ from other agricultural by-products by their honeycomb structure and their high porosity which gives them a high insulating potential. The use of these kinds of biobased materials is increasing due to their good environmental performances. The purpose of this project is to investigate the possibility of mixing pith particles with a biobased glue in order to manufacture cold pressed panels. The thermal insulation properties of these materials, as well as their mechanical properties through bending and compression tests and the impact of natural and accelerated ageing on the latter are studied. The present paper focuses on the properties of the panels at the initial stage. Two different biobased binders with various content were used to prepare the sunflower pith panels with densities ranging from 34 to 48 kg/m \(^3\) . The first binder was a commercial starch-based glue, the second one was pea starch. The results show very good thermal conductivities (from 0.040 to 0.043 W/(m.K)) and average mechanical values for these types of lightweight materials.