Thermoplastic agar blended PBAT films with enhanced oxygen scavenging activity

Abstract

The morphology and properties of biodegradable packaging comprising thermoplastic agar and poly (butylene adipate-co-terephthalate) (PBAT) blends (20/80 and 40/60 ratios) produced via cast extrusion were characterized. These polymers were blended with gallic acid (GA) and determined for oxygen scavenging activity. Increasing agar content formed non-homogeneous PBAT matrices with dispersed clumps, while GA facilitated the unfolding of agar molecules and reduced the number of clumps. GA interacted with agar and PBAT by modifying the CO and C–H stretching vibrations, causing polymer blend plasticization and decreasing the mechanical relaxation temperature. Addition of agar and GA modified the crystallinity, morphology, and barrier properties of PBAT. Compounding GA into the polymer matrices effectively enhanced oxygen scavenging, while oxygen absorption rates increased with increasing relative humidity (RH) from 50% to 100%. Rates and maximum scavenging capacity depended on GA contents and humidity at 50% RH, while higher humidity showed insignificant effects of GA contents, suggesting additional roles of polymer structures involving oxygen diffusion through the matrices. Blending thermoplastic agar at 20% in PBAT films produced biobased sustainable food packaging and effectively enhanced oxygen scavenging active functions.