Tri-(butanediol-monobutyrate) citrate plasticizing poly(lactic acid): Synthesis, crystallization, thermal, and mechanical properties

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Abstract

Tri-(butanediol-monobutyrate) citrate (TBBC) as a new plasticizer for poly(lactic acid) (PLA) was synthesized via a two-step esterification. The chemical structure of TBBC was characterized by 1H-nuclear magnetic resonance. The studies on solubility parameters, transparence, and storage stability indicated the good miscibility between PLA and TBBC. The glass transition, crystallization, thermal, and mechanical properties of PLA plasticized by TBBC were evaluated. With an increase in TBBC content, the glass transition temperature (Tg), melting point (Tm), and the cold crystallization temperature (Tcc) of plasticized PLA gradually shifted to a lower temperature. The elongation at break and flexibility were greatly improved by the addition of TBBC. After 30 days of storage, PLA plasticized with up to 20 wt% of TBBC exhibited good storage stability and remained the original transparence and mechanical properties. The flexibility of PLA/TBBC films can be tuned by changing TBBC content. The corresponding crystalline morphology and structure were investigated by Polarizing optical microscope and X-ray diffraction as well. This study revealed that TBBC was miscible with PLA and may therefore be a promising plasticizer for PLA-based packaging materials. POLYM. ENG. SCI., 55:205–213, 2015. © 2014 Society of Plastics Engineers

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