Poly(lactic acid) Toughening through Chain End Engineering

Journal Article · 05 December 2019 · ACS Applied Polymer Materials

DOI: https://doi.org/10.1021/acsapm.9b00888 · OSTI ID:1606924

Li, Kai  ^[1]; Wang, Yu  ^[1]; Rowe, Matthew ^[2]; Zhao, Xianhui ^[1]; Li, Tianyu ^[3]; Tekinalp, Halil ^[1]; Ozcan, Soydan  ^[2]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
3. Univ. of Tennessee, Knoxville, TN (United States)

The intrinsic brittleness of poly(lactic acid) (PLA) has hindered its widespread use in many structural applications. Various strategies have been developed to toughen PLA; however, most of the methods lead to a trade-off in strength or modulus. In this study, a chain end engineering strategy was developed to toughen PLA via an industry-friendly melt processing method. Green acids with multifunctional groups, such as 1,2,3,4-butanetetracarboxylic acid (BTCA), were used to modify PLA chain ends/tails via a melt reaction. We report a remarkable improvement in toughness (16×) was achieved by the addition of a minimal amount of BTCA (0.5%). At the same time, the toughened PLA samples maintained the tensile strength and Young’s modulus of neat PLA, suggesting a unique toughening mechanism that is different from the plasticizing effect. Other acid–based modifiers with different numbers of functional groups were also studied in this work. To understand the toughening, we propose a chain end engineering picture that can improve the toughness via a reduction in the number density of chain ends or defects of entanglement and the formation of long-branch topological structures. This study demonstrates a unique and cost-effective strategy for toughening PLA via scalable melt reaction without sacrificing other mechanical properties of PLA, potentially broadening the applications.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Advanced Manufacturing Office (EE-5A)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1606924
• Journal Information: ACS Applied Polymer Materials, Journal Name: ACS Applied Polymer Materials Journal Issue: 2 Vol. 2; ISSN 2637-6105
• Publisher: ACS PublicationsCopyright Statement
• Country of Publication: United States
• Language: English