Fracture toughness of hybrid natural fiber/nanoclay reinforced starch biocomposite material

Abstract

In this paper, fracture toughness of banana fiber reinforced thermoplastic starch (BF_TPS) material was studied. Fiber weight percent (30, 40, and 50 wt.%) to starch polymer was fabricated using hot press at a pressure of 5 MPa of 160°C for 30 min. Experimental result shows that 40 wt.% BF_TPS biocomposite gave optimum tensile strength. Furthermore, nanoclay with varying weight percentage (1–5 wt.%) of dry cornstarch (CS) powder was added to enhance the property of the optimum 40 wt.% BF_TPS biocomposite, hence, forming hybrid clay/BF_TPS biocomposite. Tensile, impact, and fracture mechanics (Mode I fracture test) through Single End Notched Bending (SENB) Test were studied concurrently. Thermal properties and degradations were equally studied through Dynamic Mechanical Analysis (DMA) and Thermogravimetric Analysis (TGA). Results show that tensile strength and impact resistance increased to the maximum of 65% and 15.6%, respectively, at 3 wt.% clay addition. Critical stress intensity factor ( K IC ) was approximately higher by 276% when compared to neat BF_TPS material. Strain energy release rates ( G IC ) values were minimal. Delamination and catastrophic failures occurred with less fiber crack propagation along the crack initiation notches. In TGA, less weight reduction was observed at 3 wt.% clay/BF_TPS material, while a positive shift occurred in DMA tan delta (Tan δ) T g by 30°C. The micrography of the clay-enhanced biocomposites resulted in better bonding interaction between the polymer and fiber.