Thermal and Barrier Characterizations of Cellulose Esters with Variable Side-Chain Lengths and Their Effect on PHBV and PLA Bioplastic Film Properties

Cellulose esters (CEs) are promising biodegradable substitutes for traditional petroleum-based plastic materials. Research on structure-property relationships of CEs is necessary to evaluate their suitability for industrial applications such as food packaging. Cellulose esters with different side-chain lengths were synthesized and studied. Their thermal and moisture barrier properties were characterized. Cellulose triheptanoate (CTH) was proved to have an optimal moisture barrier (WVTR = 0.31 g.mil/day/in.(2)) and was used to blend with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polylactic acid (PLA) bioplastics. CTH addition improved the PLA thermal stability, enhanced the ductility, and increased the moisture barrier by 32%, while it decreased the PHBV thermal stability, weakened the ductility, and reduced the moisture barrier by 90%. We demonstrated that by proper choice of the combination of CE and bioplastic, bioplastic blends with unique and useful synergistic properties can be obtained. These blends can potentially be used for commercial applications, such as biodegradable flexible packaging.