Synergistic morphological and mechanical properties of pressed oil palm trunk CNF/TiO₂ composite for green innovative antibacterial food packaging

Cellulose nanofibrils-based composites are renewable biomaterials with wide potential applications such as active antibacterial packaging. Derived from lignocellulosic biomass such as pineapple leaves, cellulose nanofibrils possess excellent and unique properties. Oil palm trunk (OPT), another widely available post-harvest waste in Indonesia, is an alternative source of raw material, although its mechanical processing requires a significant amount of energy input and normally involves corrosive chemicals. Isolation of cellulose nanofibrils from pressed OPT fibers was carried out using a combined chemical and mechanical approach, developing further to form cellulose nanofibril/TiO₂ composites to be used as antibacterial packaging materials. A 2.5 % (w/v) NFC slurry was mixed with TiO₂ nanoparticles (5, 10, and 15 % (w/w)) as an antibacterial agent for NFC/TiO₂ composites. First, the chemically delignified and bleached compressed OPT fibers were hydrolysed with non-corrosive succinic acid and subsequently defibrillated using ultrasonication. TiO₂ is the antibacterial agent within the composite. Optimal hydrolysis was achieved using 0.3 mol/L succinic acid with an average diameter reduction of 45.18 % and yield of 92.35 ± 1.61 %. Following ultrasonication, diameters of fibrils ranged from 25 to 170 nm, whilst most were in the range of 44 to 62 nm. The analysis is supported by experimental techniques; for example, SEM for surface morphology analysis, XRD for crystallinity and structural insight, and statistical methods to assess the significance of data and the characteristics of distribution. All the characteristics mentioned above were enhanced with added TiO₂ since tensile strength, thickness, and brightness of composites increased in the presence of TiO₂ and possessed effective antibacterial properties against the organisms Escherichia coli and Staphylococcus aureus.