Open Access

ARTICLE

Improving Polylactide Toughness by Plasticizing with Low Molecular Weight Polylactide-Poly(Butylene Succinate) Copolymer

Yottha Srithep^1,*, Onpreeya Veang-in¹, Dutchanee Pholharn², Lih-Sheng Turng³, John Morris⁴

1 Manufacturing and Materials Research Unit, Department of Manufacturing Engineering, Faculty of Engineering, Mahasarakham University, Mahasarakham, 44150, Thailand
2 Department of Chemistry, Faculty of Science and Technology, Rajabhat Maha Sarakham University, Mahasarakham, 44000, Thailand
3 Polymer Engineering Center, Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, 53705, USA
4 King Mongkut Institute of Technology Ladkrabang, Bangkok, 10520, Thailand

* Corresponding Author: Yottha Srithep. Email:

(This article belongs to the Special Issue: Polylactide Based Biopolymeric Systems)

Journal of Renewable Materials 2021, 9(7), 1267-1281. https://doi.org/10.32604/jrm.2021.015604

Received 31 December 2020; Accepted 03 February 2021; Issue published 18 March 2021

Abstract

A low-molecular-weight polylactide-poly(butylene succinate) (PLA-PBS) copolymer was synthesized and incorporated into polylactide (PLA) as a novel toughening agent by solvent casting. The copolymer had the same chemical structure and function as PLA and it was used as a plasticizer to PLA. The copolymer was blended with PLA at a weight ratio from 2 to 10 wt%. Phase separation between PLA and PLA-PBS was not observed from their scanning electron microscopy (SEM) images and the crystal structure of PLA almost remained unchanged based on the X-ray diffraction (XRD) measurement. The melt flow index (MFI) of the blends was higher as the amount of PLA-PBS increased, indicating that the block copolymer did improve the mobility of the PLA chains. Moreover, tensile tests revealed that PLA with greater PLA-PBS copolymer exhibited higher elongation at break and it reached the maximum at 8 wt% of PLA-PBS in PLA, which was around 6 times higher than that of pure PLA. Furthermore, the glass transition temperature, measured by differential scanning calorimetry (DSC), markedly decreased with an increasing amount of the copolymer as it decreased from 61.2°C for pure PLA to 41.3°C when it was blended with 10 wt% PLA-PBS copolymer. Therefore, the PLA-PBS copolymer was shown to be a promising plasticizer for fully biobased and toughened PLA.

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