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Modification of Processability and Shear-Induced Crystallization of Poly(lactic acid)
Ruiqi Feng1, Daisuke Kugimoto2, Masayuki Yamaguchi1
1Japan Advanced Institute of Science and Technology, Graduated School of Advanced Science and Technology, Asahidai, Nomi 923-1292, Ishikawa, Japan.
Polymers
|January 8, 2025
Summary
Adding ethylene-vinyl acetate copolymer (EVA) to poly(lactic acid) (PLA) reduces melt viscosity and improves melt strength. This blend modification enhances processing and crystallization, making PLA suitable for industrial use.
Area of Science:
- Polymer Science
- Materials Science
- Rheology
Background:
- Poly(lactic acid) (PLA) is a biodegradable polymer with limitations in processing and toughness.
- Ethylene-vinyl acetate copolymer (EVA) is immiscible with PLA and forms a dispersed phase.
Purpose of the Study:
- To investigate the rheological properties and crystallization behavior of PLA/EVA blends.
- To understand the impact of EVA addition on PLA's shear and elongational flow characteristics.
- To evaluate the potential of PLA/EVA blends for industrial applications.
Main Methods:
- Rheological measurements under shear and elongational flow.
- Analysis of crystallization behavior after shear history.
- T-die extrusion to observe neck-in behavior.
Main Results:
- EVA addition significantly reduced shear viscosity due to interfacial slippage.
- EVA induced strain hardening in elongational flow, reducing neck-in during extrusion.
- EVA accelerated shear-induced crystallization of PLA, without acting as a nucleator at rest.
Conclusions:
- PLA/EVA blends exhibit improved processability and mechanical toughness.
- The modification technique enhances PLA's suitability for various industrial applications.
- Interfacial phenomena play a crucial role in the blend's rheological and crystallization behavior.
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