Evaluation of distillers grains as fillers for low density polyethylene: Mechanical, rheological and thermal characterization

Low density polyethylene/distillers grains (LDPE/DG) composites have been prepared by melt extrusion. The distillers grains fillers were characterized in terms of surface morphology and particle size distribution. The composite characteristics were investigated by melt flow index (MFI), mechanical tests (tensile properties and Izod impact strength), dynamic rheological measurements and thermal stability (TG). SEM analysis showed that NaOH-treated DG feature a huge potential as reinforcing agents of LDPE due to their rough surface morphology. The introduction of 40 wt% DG in the LDPE matrix increased the tensile modulus by a factor 3 compared to the pure LDPE, which is ascribed to the higher modulus of the DG compared with LDPE. Whereas tensile strength and elongation at break of the composites decreased with the increasing of DG content. Dynamic rheological analysis showed that the storage modulus increased for all composites compared to LDPE, indicating that the addition of DG fillers to LDPE might be beneficial in applications to improve stiffness. The TG results showed that the thermal stability of LDPE/DG composites decreased slightly by adding DG as the percentage of mass loss at DG’s decomposition peak temperature increased monotonically from 4.51% to 15.13% for 10 to 40 wt% addition of DG; however, their flame retardancy leveled up. The results showed that distillers grains, as renewable raw materials, hold great potential as fillers in thermoplastic composites.