Characterization and feasibility of Mimusops Elengi seed shell powder as filler for thermoplastic materials

Mimusops elengi seed shell powder (MESSP) was prepared through drying, grinding and sieving the seed shells of Mimusops elengi (ME) fruits. Characterizations such as elemental composition, chemical functionality, specific surface area, particle size and distribution, particle shape and surface morphology, and thermal stability were studied to determine the feasibility of MESSP as filler for polypropylene (PP). The main elements that can be found in MESSP are calcium oxide, potassium oxide, sulphur trioxide, ferric oxide and titanium oxide. The main chemical functional groups of MESSP are hydroxyl, carbonyl and methyl. MESSP has mean diameter of 0.225 µm and specific surface area of 29 m2/g. Morphological analysis of MESSP showed that the particles are irregular in shape with rough surface due to the presence of pores and cracks. The particles also present majorly as an individual particle or loosely bound aggregates which suggest good dispersion in polymer matrix. Thermogravimetric analysis revealed that MESSP is 93.77% stable at composite processing temperature and showed maximum decomposition rate at 365 °C. The processing torque and melting temperature of PP/MESSP composites were not affected with the addition of MESSP up to 20 wt %, which proved that the composite is feasible to be processed at similar condition as neat PP. Morphological observation of composite also confirms partial adhesion between PP and MESSP, as well as physical interaction between PP and MESSP through PP chain penetration on the surface of MESSP particles which would potentially improve the mechanical properties of the composite.