Effect of clay contents on mechanical and water vapor barrier properties of agar-based nanocomposite films

Agar/clay (Cloisite Na+) nanocomposite films with different amount of the nanoclay (0, 2.5, 5, 10, 15, and 20 g clay/100 g agar) were prepared using a solution intercalation method. Results on X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed well developed intercalated nanocomposite films especially at low level of nanoclay addition, and their properties were greatly influenced with the clay content. Tensile strength (TS) increased with increase in the clay content up to 10%, and decreased with more than 10% of clay incorporation. Water vapor permeability (WVP), water vapor uptake ratio (WVUR5), and water solubility (WS) decreased with increase in the nanoclay content due to the tortuous path for water vapor diffusion and strong structure formed between the intercalated silicate layers and the polymer matrix. Hydrophilicity of the nanocomposite films increased with increase in the hydrophilic nanoclay, resulted in decreased water contact angle (CA) and increased swelling ratio (SR).