Glycerol-derived organic carbonates: environmentally friendly plasticizers for PLA

Area of Science:

• Polymer Science
• Materials Science
• Green Chemistry

Background:

• Polylactic acid (PLA) is a renewable, biodegradable polymer but suffers from brittleness, limiting its applications.
• Plasticizers are commonly used to improve PLA's flexibility, but their environmental impact and long-term stability are concerns.

Purpose of the Study:

• To synthesize novel biodegradable organic carbonates from renewable resources.
• To evaluate these carbonates as plasticizers for polylactic acid (PLA).
• To assess the biodegradability and long-term stability of PLA plasticized with these novel compounds.

Main Methods:

• Synthesis of four organic carbonates (1-4) using glycerol and diethyl carbonate (DEC) or dimethyl carbonate (DMC).
• Assessment of biodegradability via soil exposure at 25 °C.
• Evaluation of plasticizer efficacy and compatibility with PLA using DSC, DMA, SEM, and rheometry.
• Tensile property testing of PLA blends.
• Long-term stability and plasticizer migration studies using DMA.

Main Results:

• Synthesized organic carbonates (1-4) demonstrated rapid biodegradability under ambient conditions.
• Organic carbonate 1 proved effective as a PLA plasticizer, improving ductility up to 30 phr.
• PLA/1 blends exhibited superior morphological stability compared to PLA/ATBC blends, with no observed crystallization or plasticizer migration.
• The addition of biodegradable plasticizers did not enhance the biodegradation rate of PLA under ambient soil conditions over six months.

Conclusions:

• Novel biodegradable organic carbonates can be synthesized from renewable feedstocks.
• These compounds effectively plasticize PLA, enhancing its ductility and long-term morphological stability.
• While the plasticizers themselves are biodegradable, they do not accelerate the degradation of the PLA matrix under ambient conditions.