Fabrication and Characterization of Corn Starch-blended Polyhydroxybutyrate Films

Polyhydroxybutyrate (PHB) is a biodegradable polyester from natural resources commonly applied in food packaging due to its fast biodegradation. This study investigates PHB as a primary matrix with corn starch as a supplementary reinforcement. Traditional casting method was used with different weight ratios of PHB and corn starch (50/50, 60/40, and 70/30). Mechanical properties, morphological characteristics and structural analyses were evaluated using Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. A field emission scanning electron microscope (FESEM) with energy-dispersive spectroscopy (EDS) was employed to study biodegradation in the PHB-corn starch combinations. The SEM images revealed that corn starch is uniformly dispersed within the PHB matrix, particularly in the 50/50 and 70/30 ratios, while the 60/40 ratio showed pore formation due to poor dispersion. Similarly, FTIR indicated that no interfacial intermetallics were present in the PHB-corn starch blends at the 60/40 ratio, which also displayed lower tensile strength compared to the other two blends, attributed to particulate agglomeration. Soil burial tests revealed that the optimal proportion of PHB:Corn starch is 70:30.