Characterization of PVA/cassava starch biocomposites fabricated with and without sonication using bacterial cellulose fiber loadings

•PVA/starch (non-sonicated and sonicated) blends film were reinforced by BC fibers.•Opacity, tensile testing, XRD, FTIR, and TGA were used to characterize the films.•Sonicated blends film shows lower tensile strength than the non-sonicated one.•Sonicated biocomposite film had better performance than the non-sonicated one. This paper reports the characterization of polyvinyl alcohol (PVA)/cassava starch biocomposites. The cassava starch gel with or without ultrasonic probe treatment was mixed with PVA gel then short bacterial cellulose fibers were added. The presence of the sonicated starch gel in the PVA resulted in low thermal and moisture resistance, and low transparency of the blend film. After adding the fibers thermal and moisture resistance of the sonicated biocomposite increased due to stronger hydrogen bonding between the fibers and the matrix. Tensile strength of sonicated biocomposite with 10 g fibers increased 215% compared to the sonicated blend. However, addition of the fibers to the non-sonicated blend did not significantly increase mechanical and thermal properties or moisture resistance of the biocomposite. Opacity of the non-sonicated biocomposite was lower than that of the sonicated one.