Valorization of date palm wastes as sandwich panels using short rachis fibers in skin and petiole 'wood' as core

Algerian agriculture offers free by-products that can be transformed in biobased-materials. We use one of them, the date palm 'wood', to locally develop sandwich panels. We demonstrate by tensile tests that rachis fibers are more efficient than petiole fibers. Then, petiole 'wood' is used as sandwich core and short rachis fibers (5%, 10%, 15%) are used as epoxy skin reinforcement. The skins are tested by tensile and bending tests, 15%Mf untreated short fibers have been selected as a best choice for stiffness of the skins. Three parameters are studied to optimize the design of the core: the orientation (longitudinal, transverse, radial), the length of the pieces of 'wood' (30 mm, 100 mm), and the thickness (10 mm, 15 mm, 20 mm). The sandwich efficiency are studied by 3-points bending tests combined to linear elastic beam theory and failure mode analysis. The dominant failure modes are bottom skin failure and core shear, the latter being not activated in case of transverse orientation of core. Both other parameters (thickness, pieces of core length) are not really determinant in mechanical point of view, depending on the future use. We conclude that making sandwich board by using untreated short rachis fibers as reinforcement for skins and untreated transverse cut petiole 'wood' as core is a very efficient choice to give technical and cheap valorization of palm leaf wastes for non-structural use.

Automated summary

Algerian agriculture provides free by-products that can be converted into biobased materials. The study found that using untreated short rachis fibers as reinforcement for skins and untreated transverse cut petiole 'wood' as core to make sandwich panels is a highly efficient choice for technical and cost-effective utilization of palm leaf waste for non-structural use.