In this work, the influences of different concentration of sodium hydroxide (NaOH) (3, 6 and 9 wt.%) on the flexural and impact properties of linear low-density polyethylene / date seeds (LLDPE/DS) composites were examined. The LLDPE / DS ratio was fixed at 90/10 wt.% and the size of DS particles was measured at 125 - 250 micro m. The process used to synthesize the composites id extrusion followed by injuction molding process. Results showed that the presence of NaOH particularly at 6 wt.% concentration has improved the flexural and impact properties of the composite. This is due to bonding of the date seeds particles with the LLDPE matrix that reflected posativelly on the mechanical properties of the composite. However, the using of high NaOH concentration (9 wt.%) has shown an opposite trend, the increasing of surface roughness of the fiber after 9% NaOH treatment has reduced the flexibility of the composite and made it stiffer and more rigid, which in turn made it easy to break during mechanical test.
