Mechanical, morphological and water absorption properties of polyethylene/olive pomace flour bio-composites

Mechanical and physical properties of various weigh percentages (0% - 40%) of olive pomace flour (OPF)-loaded linear low density polyethylene (LLDPE) in the presence of 0%, 5% and 10% coupling agent (C) were formulated and studied. Extrusion and hot press processing techniques were used to fabricate OPF/LLDPE composites. Tensile stress at yield increased by 20% with the increasing of the filler loading up to 20%; and marginally increased in the presence of the C. Whereas, the decline in the tensile strain at yield of the polymer composite improved with the increase in the C content. The modulus increased from 631 MPa for the neat LLDPE to 680, 808 and 700 MPa for the composites filled by 5%, 10% and 20% filler content, respectively. Whereas, a decrease in the given modulus (550 MPa) was observed at 40% filler loading. The modulus has shown a successive improvement upon the addition of the C with values not less than 800 MPa. The impact strength decreased with the increase in filler loading from 119 kJ/m2 for the neat LLDPE to 81, 43, 27 and 16 kJ/m2 for the 5%, 10%, 20% and 40% OPF/LLDPE samples, respectively. On the contrary, 10% C addition improved the impact strength of the composite by two folds in the case of 10 - 40% filler inclusion. The scanning electron microscopy (SEM) illustrations proved the mechanical performance of various bio-composite formulations. Water absorption of the bio-composite increased with the OPF loading, from 0.73% for the neat LLDPE to 2.6% for 40% OPF-filled polymer composite, and decreased upon increasing the C content with an average of 1.4% for all composites. Formulated by mixing cellulosic-based material OPF and LLDPE, the bio-composite demonstrated compatible physical properties and can be used as an already available cellulosic filler for the bio-composite materials.