Starch-based biocomposite films have drawn considerable attention on food packaging due to their attractive combination of low price, environmental friendly, and abundance. Nevertheless, the use of starch-based biocomposite films in industrial application were restricted by its poor tensile properties, poor water resistance and naturally intractable behavior. The aims of this research work were to develop crosslinked starch-based biocomposite films and to investigate the effects of nanocellulose (NC) and crosslinking agent on tensile, physical, water resistance, thermal and biodegradation properties of tapioca starch (TS) biocomposite films. The NC was extracted from oil palm empty fruit bunch (OPEFB) via acid hydrolysis. Fourier transform infrared spectroscopy analysis on NC verified that the chemical treatments and acid hydrolysis removed non-cellulosic constituents including hemicelluloses and lignin from OPEFB. X-ray diffractograms revealed that the crystallinity of NC increased from 43.1% of raw OPEFB to 65.8%. Transmission electron microscope image confirmed the diameter of NC was in nano-sized with needle like structure. TS/NC biocomposites with glycerol as plasticizer were prepared using solution casting method by varying amounts of NC. Crosslinker, namely Citrus aurantifolia, also known as lime juice (LJ), was introduced for TS crosslinking. At the same time, commercial citric acid (CA) was used as crosslinker for comparison purposes. Crosslinking between TS and LJ through esterification were validated through the Fourier transform infrared spectroscopy, degree of substitution and degree of di-esterification results. Ten parts per hundred starch (phs) of LJ enhanced the flexibility of TS biocomposite as its break elongation of 106 % was the highest, while NC (1 phs) increased its tensile strength with the highest value of 13.5 MPa. Crosslinkers did not considerably affect the optical property of TS biocomposites but the addition of NC reduced its transparency. TS biocomposite films with both LJ and NC have lower water vapor permeability (WVP). The WVP of LJ-crosslinked TS film with 1 phs NC reduced about 55%, compared to neat TS film. The crystallinity of TS film increased from 43.5 % for neat TS to 51.6 % for TS film with addition of NC. LJ-crosslinked TS film with 1 phs of NC had the lowest moisture absorption and swelling ratio, indicating the improvement of water resistance of TS. TS biocomposites with both NC and LJ also had better thermal and biodegradation behavior. This outcome showed that LJ is usable in starch crosslinking as the results obtained were comparable to those of the commercial CA. The developed LJ-crosslinked TS biocomposites with enhanced tensile properties, water resistance and thermal properties could be used as food packaging, especially for dry food.
