Fracture of Corn Endosperm in Bending Part II: Fracture Analysis by Fractography and Optical Microscopy
ABSTRACT FRACTURE in corn endosperm, studied by both a scanning electron microscope and an optical microscope, occurs as an intergranular brittle fracture at lower temperatures, but as an intergranular ductile frac-ture at higher temperatures. The mode of crack propagation is not affected by temperature and rate of loading since there were no ap-parent differences between ruptured surfaces due to bending as simple beams and stress-crack surfaces due to heated-air drying. The fracture in corn endosperm was found to initiate in the center of the kernel, apparently due to internal flaws, and propagate toward the outside through the cell walls and around the starch granules.