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Esterification of Condensed Tannins and Their Impact on the Properties of Poly(Lactic Acid)
Biopolymer Network Ltd and Manufacturing & Bioproduct Development, Scion, Rotorua, 3046, New Zealand
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Received: 25 February 2013; in revised form: 6 March 2013 / Accepted: 11 April 2013 / Published: 19 April 2013
Abstract: 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.
Keywords: condensed tannins; polyphenolics; esterification; poly(lactic acid) (PLA); plastic additives
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MDPI and ACS Style
Grigsby, W.J.; Bridson, J.H.; Lomas, C.; Elliot, J.-A. Esterification of Condensed Tannins and Their Impact on the Properties of Poly(Lactic Acid). Polymers 2013, 5, 344-360.
Grigsby WJ, Bridson JH, Lomas C, Elliot J-A. Esterification of Condensed Tannins and Their Impact on the Properties of Poly(Lactic Acid). Polymers. 2013; 5(2):344-360.
Grigsby, Warren J.; Bridson, James H.; Lomas, Cole; Elliot, Jaime-Anne. 2013. "Esterification of Condensed Tannins and Their Impact on the Properties of Poly(Lactic Acid)." Polymers 5, no. 2: 344-360.