Biocomposites based on Argan nut shell and a polymer matrix: Effect of filler content and coupling agent

• Polymer bio-composites with Argan nut shell Fillers (ANS) are produced and tested.
• The effect of filler content and coupling agent on the properties is evaluated.
• Dynamic mechanical characterization is carried out.
• ANS may be considered as possible reinforcements of thermoplastics bio-composites.

This study aimed at developing a biocomposite using polypropylene (PP) as the matrix and Argan nut shell (ANS) as reinforcement. Also, styrene–(ethylene–butene)–styrene triblock copolymer grafted with maleic anhydride (SEBS-g-MA) was used as a coupling agent. The samples were prepared by using extrusion compounding followed by injection molding to determine the effect of filler and coupling agent content on the morphological, thermal, mechanical, and hygroscopic properties of the biocomposites. SEM micrographs revealed that good ANS dispersion/distribution into PP was achieved with an important reduction of fiber pull-out, micro-spaces, and voids with coupling agent addition. This led to substantial improvement intension, torsion, and water absorption reduction due to improved interfacial adhesion. Although ANS particles did not significantly modify the thermal stability of PP, the use of a coupling agent increased it. The experimental data were compared with several theoretical models such Voigt, Reuss, Hirsch, and Tsai–Pagano to characterize the interfacial adhesion quality and to determine the elastic modulus of a single ANS particle. Finally, all the results show that Argan waste to produce PP biocomposites is an interesting avenue to effectively deal with agricultural wastes and develop valuable industrial and practical applications.