Properties of particleboards made of agricultural by-products with a classical binder or self-bound

•Sunflower bark can replace flax shives in particleboards made with a binder.•Self-adhesion is better with flax shives thanks to their biochemical composition.•Binderless boards made of flax shives present interesting bending strength.•Fire resistance of binderless particleboards is better than that of boards containing UF resin. In order to replace wood in particleboard manufacturing, two agricultural by-products were studied: the flax shives and the sunflower bark, which are abundant, renewable and little valorized raw materials. Sunflower bark in particular is very few studied. This study will demonstrate the possibility of using sunflower bark in particleboards and how to modulate the manufacturing process to take the benefits of both studied agroresources. These plant based particles present interesting porous structures for using as materials for building insulation or as furniture. To obtain totally biosourced materials, the plant based particles were self-bound by a thermocompression process with water. The properties of these materials were compared with particleboards made of the same plant based particles with a classical urea-formaldehyde binder. Particleboards of two target densities are compared: 350 and 500 kg m−3. Both agroresource materials do not present the same behavior to self-binding or classical binding. Flax shives are more adapted to self-binding process thanks to their biochemical composition and their morphological structure. These different boards were characterized according to mechanical and thermal properties, resistance to water and to fire. The type of agroresource or of binder does not influence the thermal conductivity. The denser binderless boards show better resistance to fire. The main defect of binderless boards is their too low resistance to water compared to boards made with a synthetic binder.