Preparation and characterization of biodegradable PLA polymeric blends

Area of Science:

• Materials Science
• Biomaterials Engineering
• Polymer Chemistry

Background:

• High molecular-weight poly-L-lactic acid (PLLA) is brittle and has a long degradation time, limiting its use in orthopedic and dental surgery.
• Modifications like adding plasticizers or surfactants are needed to improve PLLA's mechanical properties and reduce degradation time.

Purpose of the Study:

• To enhance the toughness of high molecular-weight poly-L-lactic acid (PLLA) while maintaining its strength.
• To improve PLLA's suitability for orthopedic and dental applications through material modification.

Main Methods:

• Blends of PLLA with poly-DL-lactic acid (PDLLA) or polycaprolactone (PCL) were prepared in various ratios using dichloromethane.
• A surfactant (copolymer of ethylene oxide and propylene oxide) was added to some blends.
• Characterization included differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and mechanical property testing.

Main Results:

• PLLA/PDLLA blends with surfactant showed a single glass transition temperature (T(g)) indicating improved miscibility.
• The 50/50 PLLA/PDLLA/2% surfactant blend exhibited the highest elastic modulus, yield strength, and break strength.
• The addition of PDLLA and surfactant significantly increased the elongation at break compared to pure PLLA.

Conclusions:

• Solution-blending PLLA with PDLLA and a surfactant effectively improves toughness and elongation at break.
• The modified PLLA blends demonstrate enhanced mechanical properties, making them promising for orthopedic and dental applications.