Tuning polylactic acid performance using green citrate plasticizers of varying chain lengths

Area of Science:

• Materials Science
• Polymer Science
• Chemical Engineering

Background:

• Polylactic acid (PLA) is a biodegradable polymer with limited ductility.
• Plasticizers are additives used to increase polymer flexibility.
• Understanding plasticizer effects is crucial for tailoring PLA properties.

Purpose of the Study:

• To investigate the effects of plasticizers on PLA's mechanical, thermal, and shape memory properties.
• To identify optimal plasticizer concentrations for enhanced deformability.
• To explore the relationship between plasticizer content, chain mobility, and crystallization.

Main Methods:

• Mechanical testing (tensile strength, elongation at break).
• Thermal analysis (differential scanning calorimetry for glass transition temperature).
• Thermomechanical analysis.
• Shape memory recovery tests.
• Exposure to food simulants to assess plasticizer migration.

Main Results:

• Triethyl citrate (TEC) at 20 wt% significantly enhanced PLA elongation to 307%, while reducing tensile strength to 25.2 MPa.
• A decrease in glass transition temperature from 59.6°C to 19.3°C confirmed increased chain mobility.
• Plasticizers promoted crystallization and affected shape memory recovery.
• Plasticizer migration was observed, correlating with increased free volume and ductility.

Conclusions:

• Plasticizers effectively improve PLA's ductile properties and lower its glass transition temperature.
• Optimal plasticizer concentration is critical for balancing deformability and mechanical integrity.
• Plasticizer migration is a key factor influencing long-term properties and potential applications, especially in food contact materials.