Size effect of ZnO nanorods on physicochemical properties of plasticized starch composites

Abstract

tThis work demonstrates that the size of ZnO nanorods (ZnONR) with similar aspect ratio determines sev-eral physicochemical and microbiological properties of thermoplastic starch composites (TPS/ZnONR) ata given concentration of ZnONRs. A combination of sol-gel and hydrothermal methods was developed tosynthesize ZnONR with different sizes but similar aspect ratios. Starch composites containing 1 wt.% ofZnONR were prepared by casting. Composites with smaller size nanorods (ZnONR-S) showed more effi-ciency in shielding UVA radiation and had a higher solubility and water vapor permeability than thosewith larger nanorods (ZnONR-L). Mechanical properties, biodegradability and antibacterial activity werealso influenced by the size of the ZnONR. X-ray diffraction analysis showed that composites with ZnONR-S maintained the typical B-V type starch structure, intensifying the V-type starch structure peaks, whilecomposite with ZnONR-L induced the formation of an amorphous structure, preventing starch retrogra-dation during storage. Properties affected by nanorods size are fundamental in determining composite applications.