Rheological, Thermal, and Degradation Properties of PLA/PPG Blends

Area of Science:

• Polymer Science
• Materials Science
• Rheology

Background:

• Polylactic acid (PLA) is a biodegradable polymer with processing challenges.
• Understanding polymer melt viscosity and molecular weight relationships is crucial for material processing.
• Polypropylene glycol (PPG) is explored as a plasticizer for PLA.

Purpose of the Study:

• To simulate the compounding process of PLA/PPG composites using a torque rheometer.
• To investigate the relationship between melt viscosity, polymer molecular weight (MW), and plasticization.
• To predict the plasticization effect of PPG with varying MWs on PLA.

Main Methods:

• Torque rheometry was used to simulate the compounding process.
• Capillary rheometry and torque rheometry were employed to study rheological properties.
• Real-time monitoring of initial degradation during melt processing was conducted.

Main Results:

• PPG significantly reduced the melt viscosity of PLA/PPG composites, inducing pseudoplastic behavior.
• A lower molecular weight of PPG led to a lower composite viscosity.
• PPG addition promoted PLA degradation, with increased degradation at lower PPG MWs.

Conclusions:

• PPG effectively plasticizes PLA, reducing melt viscosity and improving processability.
• The molecular weight of PPG is a critical factor influencing the rheological properties and degradation of PLA composites.
• Optimizing PPG MW can tailor PLA composite properties for specific applications.