Effect of pH on Physico-Chemical and Mechanical Properties of Composite Films

Ramnath* V., Gajalakshmi M., lalitha J., Sekar S., Sankar S.


The effect of pH on physico-chemical and mechanical properties of composites films prepared from natural resources was reported in this study. Composite films varying in their pH (range 3-7) containing soya protein (SY) and sago starch (SG) were prepared by solvent casting method. These films were cross linked with glutaraldehyde to improve their mechanical properties. The films prepared were characterized for their water absorption, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), mechanical properties and thermogravimetric analysis (TGA). The results obtained showed that change in pH of the SG-SY-G composite from its native pH of 5, has significantly influenced the water absorption capacity, and rearrangement in the functional groups. An increase in the thermal stability was observed beyond the native pH and thermally unstable below the native pH (i.e pH3 and 4). The scanning electron microscope studies have shown a smooth surface of the SG-SY-G film in the pH range 3, 4 and 5 and presence of smooth surface with granules in the pH 6 and 7. This study revealed that change in the pH of soya protein from its native pH 5, has influenced notable changes in its physico-chemical and mechanical properties to that of other composites prepared in other pH range.


pH; Composite film; soya protein; sago starch; Biomaterial.

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