Fabrication of starch - Nanocellulose composite fibers by electrospinning

Electrospinning has become an increasingly attractive technique to produce micro-to nano-scale fibers from bio-based polymers, including starch. Compared to their synthetic counterparts, fibers electrospun from bio-based polymers generally have inferior mechanical strength. In the present study, we aim to enhance the mechanical strength of electrospun starch-based fibers by using nanocellulose as a reinforcing filler and cationic starch as a binding agent. The potential ionic bonding between cationic starch and anionic nanocellulose, and the hydrogen bonding as well as macromolecular entanglement between the three components, are expected to improve the compatibility of polymers and the mechanical strength of their composite fibers. Rheological properties of nanocellulose, cationic starch, and their mixtures were studied to understand their conformation and interaction in DMSO dispersions. The rheological properties of the ternary systems were studied and correlated with their electrospinnability and the tensile strength of the composite fiber mats. Our results suggested that nanocellulose-cationic starch at its percolation concentration (≈2%, w/w, of starch) has the most profound influence on fiber strength, and CS:NC ratios of 1:2 and 1:1 created improved intermolecular ionic bonding for reinforcing the fiber structure.