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Microstructure and Performance Evolution of Poly(l-Lactic Acid) during Physical Aging: Effect of Molecular Weight
Zhi-Xuan Zhang1, Chao-Qun Wu1, Yi-Fan Zha1
1School of Chemistry, Key Laboratory of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031, China.
Biomacromolecules
|October 13, 2025
Summary
Molecular weight impacts poly(l-lactic acid) (PLLA) physical aging by affecting cohesional entanglements. Higher molecular weights delay aging, showing a nonlinear increase and saturation effect in PLLA materials.
Area of Science:
- Polymer Science
- Materials Science
- Physical Chemistry
Background:
- Poly(l-lactic acid) (PLLA) is increasingly used due to environmental concerns.
- Physical aging significantly alters PLLA's microstructure and properties.
- Understanding PLLA aging mechanisms is crucial for material stability.
Purpose of the Study:
- To elucidate the mechanism of molecular weight's influence on PLLA physical aging.
- To investigate how molecular weight affects the physical aging timeline.
- To provide a theoretical framework for PLLA aging behavior.
Main Methods:
- Utilized cohesional entanglement theory to analyze PLLA aging.
- Investigated the relationship between molecular weight and aging kinetics.
- Observed the "growth process" of cohesional entanglements in PLLA.
Main Results:
- Higher molecular weight PLLA showed inhibited entanglement growth, delaying physical aging.
- The influence of molecular weight on aging exhibited a nonlinear increase.
- A "saturation effect" was observed in the relationship between molecular weight and PLLA aging.
Conclusions:
- Molecular weight is a key regulatory parameter for PLLA physical aging.
- Cohesional entanglement dynamics govern the observed aging behaviors.
- This study offers a theoretical basis for controlling PLLA aging via molecular weight manipulation.
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