Investigation of cross-linked PVA/starch biocomposites reinforced by cellulose nanofibrils isolated from aspen wood sawdust

In this study, a bio-based composite prepared from cross-linked polyvinyl alcohol/starch/cellulose nanofibril (CNF) was developed for film packaging applications. For this purpose, CNF, as reinforcing phase, was initially isolated from aspen wood sawdust (AWS) using chemo-mechanical treatments, and during these treatments, hydrolysis conditions were optimized by experimental design. Morphological and chemical characterizations of AWS fibers were studied by transmission electron microscopy, scanning electron microscopy, Kappa number, and attenuated total reflectance-Fourier transform infrared spectroscopy, as well as National Renewable Energy Laboratory and ASTM procedures. Morphological images showed that the diameter of the AWS fibers was dramatically decreased during the chemo-mechanical treatments, proving the successful isolation of CNF. Moreover, chemical composition results indicated the successful isolation of cellulose, and Kappa number analysis demonstrated a dramatic reduction in lignin content. Mechanical, morphological, biodegradability, and barrier properties of biocomposites were also investigated to find out the influence of CNF on the prepared biocomposite properties. The mechanical results obtained from tensile analysis revealed that Young’s modulus and ultimate tensile strength of biocomposite films were enhanced with increasing CNF concentration, while a significant decrease was observed in elongation at break at the same concentration of CNF. Furthermore, with adding CNF, barrier properties and resistance to biodegradability were increased in films, whereas film transparency gradually declined.