How do different ratios of cow bone and cassava cortex affect the tensile strength of hybrid epoxy composites intended for automotive applications?
The study revealed that the ratio of cow bone and cassava cortex reinforcement significantly influences the tensile strength of the resulting hybrid epoxy composite. Six different reinforcement compositions were investigated:
- 0% cow bone / 0% cassava cortex (pure epoxy),
- 40% cow bone / 0% cassava cortex,
- 30% cow bone / 10% cassava cortex,
- 20% cow bone / 20% cassava cortex,
- 10% cow bone / 30% cassava cortex,
- 0% cow bone / 40% cassava cortex.
Among these, the hybrid composition of 20% cow bone and 20% cassava cortex (denoted as R4) yielded the highest tensile strength of 91.80 MPa, especially when combined with 4% NaOH treatment and 100 µm particle size. This indicates a synergistic effect between the two bio-fillers, likely due to enhanced interfacial bonding, complementary mechanical characteristics, and increased filler distribution efficiency.
In contrast, samples with only one type of reinforcement or lower reinforcement content exhibited lower tensile strengths. The unreinforced epoxy (0% filler) had the lowest strength at 72.66 MPa, confirming that both cow bone and cassava cortex significantly contribute to strength enhancement.
The observed trend shows that:
- Increasing the reinforcement ratio initially increases tensile strength, up to an optimal point (20/20 mix),
- Excessive filler content or imbalance in ratio (e.g., 40% of one filler) may reduce performance due to agglomeration or poor stress transfer.
Therefore, the ratio of cow bone to cassava cortex plays a crucial role in determining mechanical properties, with the balanced 1:1 ratio (20% each) providing the best tensile performance for automotive-grade composites.