The corn flour was hydrolyzed and microfluidized to reduce the particle size. The particle size analysis showed that the
size distribution was inhomogeneous with a small fraction of larger particles, but 91% of the hydrolyzed corn flour had an
average size of 300 nm, a reduction of 33 times compared to un-hydrolyzed corn flour. The reduction in the particle size
and the corresponding increase in total particle surface area were reflected in the tensile properties of their natural rubber
composites. Compared to un-hydrolyzed CF composites, the composites filled with 10–40% hydrolyzed CF had a significant
increase in tensile strength at break (29–48%), Young’s modulus (16–74%), and toughness at break (33–55%), but a decrease
in the elongation at break (4–29%). The 300% modulus also increased 2–3 times. The swelling studies indicate that particles
agglomerated at filler concentrations greater than 20% for both hydrolyzed and un-hydrolyzed CF composites. Such particle
agglomeration was significantly reduced after CF was oxidized to introduce particle–particle repulsion with negatively
charged carboxylic acid functional groups. However, the CF with the high level oxidation interfered with sulfur crosslinking
process and behaved like a scorch retarder. It was concluded that an optimum level of oxidation should be less than the low
level oxidation used in this study. Reinforcement effect was studied with dynamic shear modulus at linear viscoelastic
region. A reasonable fit to experimental data was obtained with Halpin–Tsai and Guth model for anisotropic reinforcement
elements based on the structure defined by modulus contrast in the models. The aspect ratio of the reinforcement elements
also decreased as the temperature increased, indicating polymer softening within the reinforcement elements.