The effects of notch-geometries and tensile speed on the fracture strength of jute-fiber-reinforced polypropylene (JF/PP) were investigated. Jute fiber is extracted from the stems of plants and has advantages such as low cost and low energy requirements during manufacture compared to conventional fibers such as glass. In addition, JF/PP can be more easily recycled (by methods including thermal recycling) compared to glass-fiber-reinforced plastics. In the present study, JF/PP plates containing 30 wt. % jute fiber were prepared by injection molding. The notch-root radii were 0.5 mm, 1mm, and 2 mm, while the notch depth ranged from 2 to 5 mm. Tensile tests were performed on the JF/PP plates at cross-head speeds of 103 mm/s, 102 mm/s, 10 mm/s, 1 mm/s, 8.33 × 10-3 mm/s, and 8.33 × 10-5 mm/s, at a temperature of 23 ± 1 °C. In order to gain insight into the process of micro-cracking, the notch-root surface was observed with a microscope. The microscopic observations revealed that micro-cracks were present only near the notch-root immediately before the fracture. Further, during the tensile tests, all the notched specimen were found to exhibit brittle fracture at the maximum load. The maximum elastic stress at fracture was determined using the notch-root radius and the time-to-fracture. However, it was independent of notch-depth. The results obtained can be explained based on the concept of stress-field intensity near the notch-root. Furthermore, the applicability of a fracture criterion based on the stress-field intensity near the notch-root was verified for the case of JF/PP.
