Polyphenol

Engineering

Condensed tannin

Polymer chemistry

Bacteria

Biology

Materials science

Chemical engineering

Food science

Proanthocyanidin

Polymer

Genetics

Organic chemistry

Glass transition

Lactic acid

Antioxidant

Tannin

Chemistry

Polymer science

Polymers

Reported is a study evaluating the potential of esterified tannins as plastic additives in poly(lactic acid) (PLA). Tannin esterification using anhydrides was investigated as a route to synthesize tannin esters possessing varying ester chain length and degree of substitution (DS). Esterification decreased the tannin UV absorbance, predominately in the UVB region. However, tannin materials with longer ester chain lengths exhibited melt behaviors suitable for processing in plastics. On compounding into PLA, tannin hexanoate esters lowered the PLA glass transition by 5–6 °C. Shorter chain length tannin esters had a reduced effect on PLA polymer properties. The PLA flexural properties were significantly altered with stiffness decreases of up to 15% depending on ester chain length and loading. Artificial weathering of modified the PLA samples suggests the presence of tannin esters may confer a protection role to PLA on extended exposure. Overall, results suggest scope for the use of tannin esters possessing longer ester chain length as plastic additives.

Esterification of Condensed Tannins and Their Impact on the Properties of Poly(Lactic Acid)