Thermoplastic starch (TPS) reinforced by 1 wt % nanofiber cellulose (NFC) reinforcing from water hyacinth was produced. Ultrasonic vibration time (UVT) was applied to bionanocomposites during gelation for 0, 15, 30 and 60 min. Morphology of the NFC was investigated using Transmission Electron Microscopy (TEM). Scanning Electron Microscopy (SEM) and tensile tests were performed to identify the fracture surface and determine the mechanical properties of the bionanocomposites, respectively. The Crystallinity index (CI) of untreated and treated bionanocomposites was measured using X-ray Diffraction (XRD). The average diameter of NFC water hyacinth was 10–20 nm. The maximum tensile strength (TS) and modulus elasticity (ME) of the bionanocomposite was 11.4 MPa and 443 MPa respectively, after 60 min UVT. This result was supported by SEM which indicated good dispersion and compact structure.

Cellulose fiber was isolated from bengkoang (Pachyrhizus erosus) tuber peel. A suspension consisting of distilled water, starch, and glycerol was mixed with various cellulose loadings (0, 2, 6, and 10 g) then gelatinized using a hot plate with a magnetic stirrer. The biocomposite gel was sonicated using an ultrasonication probe (47.78 W/cm² for 4 min). Scanning electron microscopy (SEM) micrographs for the fracture surface of resulting biocomposite films displayed a rougher surface than starch film, indicating fiber dispersion in the matrix. The opacity and moisture resistance of biocomposite films increased with the addition of cellulose. The opacity was at a maximum value (243.05 AUnm) with 10 g fiber, which was 11.27% higher than the starch film without cellulose. Moisture absorption of this biocomposite was 16.79% lower than the starch film. Fourier transform infrared (FTIR) confirmed this more hydrophobic nature with lower transmittance at –OH stretching in the composite than the starch film. The addition of cellulose fiber into the matrix also increased the crystallinity index.