Bio-based sustainable composites from hazelnut shell and PP/SEBS blends

In this study, waste hazelnut shells (HNS) were powderized and used as the filler for the fabrication of sustainable polymeric composites. HNS based composites can be used for many applications because of their tunable intrinsic brown color for various indoor and outdoor applications including decking applications and furniture that require a natural esthetic appearance. Polypropylene (PP), styrene-b-(ethylene-co-butylene)-b-styrene (SEBS), and 50/50 PP/SEBS blends were used as the polymeric matrixes. HNS concentration was set to 2.5, 5, and 10 wt%. PP/SEBS blend and HNS filled granules were prepared by melt mixing in an extruder. Following that polymeric films were fabricated from the granules by compression molding. The morphological, structural, thermal, mechanical, contact angle, water absorption analyses were performed in order to characterize the composites. Matrix type and filler concentration were found significant for the properties. PP/SEBS blends showed homogeneous morphology. At low concentrations, fillers were well-dispersed. On the other hand, at 10 wt% HNS loading agglomerations were observed and mechanical properties showed a noticeable drop. PP-based composites showed the highest tensile strength and elastic modulus with the lowest tensile strain. SEBS-based composites showed the lowest tensile strength and elastic modulus with the highest tensile strain. PP/SEBS composites showed mechanical properties between PP and SEBS. The incorporation of SEBS into PP increased the flexibility of the composites and resulted in relatively higher strain at break.