Design and engineering of sustainable biocomposites from ocean-recycled polypropylene-based polyolefins reinforced with almond shell and hull

Abstract

In this work, we discuss the development of a bio-based polypropylene composite by using recycled polypropylene (rPP) and almond shell with hull as green phases. In the first step, a blend of rPP and virgin PP (vPP) was manufactured and evaluated. The melt flow index (MFI) of the blend was higher (∼20 g/10 min) as compared to the neat rPP (∼3 g/10 min). With the introduction of polyethylene-octene elastomer (POE), the impact properties improved dramatically from 29.5 J/m to 203 J/m while the MFI remained close to ∼20 g/10 min which is ideal for injection molding applications. A finely ground almond shell powder was introduced to produce the composites at 20 wt.% filler content. The particle-matrix interface was clearly improved by the addition of 3% maleic anhydride grafted polypropylene (MA-g-PP), as observed in the SEM images. The good particle-matrix interfacial adhesion also improved the tensile and impact strengths by 17% and 15%, respectively. Results obtained in these experiments prove that recycled PP-almond shell reinforced composites show promise for the preparation of alternative new green materials to those manufactured with 100% non-upcycled materials.