Zein-Based Materials: Effect of Nanocarbon Inclusion and Potential Applications

Zein-based materials were produced by dissolving zein water at pH 13, and subsequently congealing it with CaCl 2 . Biocarbon particles were produced with miscanthus biomass by pyrolization at 650 °C (M-L) and at 900 °C (M-H), followed by ball-milling. Increasing the pyrolization temperature caused the disappearance of functional groups on the particle surface and increased their hydrophobicity of the particles (as shown through Attenuated Total Reflection- Fourier Transform Infrared Spectroscopy, ATR-FTIR and by the preferential partitioning on the particles in toluene rather than water). Therefore, hydrophobic interactions were likely stronger between zein and M-H particles, than between zein and M-L particles. Measurements conducted using a zeta sizer showed that aggregates of zein and M-L particles were > 1 µm, and aggregates of zein and M-H particles were G″ ≅ 5.7 × 10 4 Pa with M-H and G′ ≅ 4.3 × 10 4 Pa and G″ ≅ 4.6 × 10 4 Pa without zein). M-H particles also increased the tensile strength of zein materials, potentially improving their usefulness as bioplastics. M-L particles increased the viscoelastic moduli of zein (G′ ≅ 6.7 × 10 4 Pa and G″ ≅ 7.3 × 10 4 Pa), but did not render the material elastic (i.e. G′ was not greater than G″). Moreover, M-L particles stiffened zein at small elongational deformations, but rendered it brittle at larger deformations. M-H particles greatly reduced the permeability of zein barriers injected in sandy media, which can be for instance used to prevent the migration of subsurface contaminants. Flow reduction was 90% with zein and M-H, whereas it was 64% with zein only and 68% with zein and M-L particles and zein. Graphic Abstract