Mechanical and Thermal Properties of Polypropylene Reinforced with Almond Shells Particles: Impact of Chemical Treatments

Polypropylene (PP) matrix composites reinforced with chemically treated Almond Shell (AS) particles with and without compatibilizer (PP-g-MA) was prepared by a twin-screw extrusion at loading of 20 wt.% AS particles. Two types of chemical treatments (alkali treatment with sodium hydroxide and etherification with dodecane bromide) of the particles were carried out to improve the interface adhesion between particles and PP matrix. Results show that chemical modifications of AS particles affect the mechanical and viscoelastic properties of AS/PP composites. The composites reinforced with alkali treated particles and the compatibilized matrix lead to a notable increase in the Young's modulus (14%) compared to the composites with untreated AS particles. The ductility of composite was also evaluated by the yield strain, and results show a notable increase (31%) compared to that of composites with untreated particles. The thermal stability increased with the use of etherification (385 degrees C), with gains in the temperature up to 23 degrees C compared to neat PP (362 degrees C). The achieved results show that the AS/PP composites can be used in several applications. A thermoplastic matrix compsite mixed with treated AS particles appears to be a good alternative to obtain environmentally friendly products.