Preparation and properties of poly(L-lactide)/hydroxyapatite composites

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Materials Engineering

Background:

• Poly(L-lactide) (PLLA) is a biodegradable polymer with potential biomedical applications.
• Hydroxyapatite (HA) is a bioceramic known for its osteoconductivity.
• Combining PLLA with HA can create composite materials with improved properties for tissue engineering and orthopedic applications.

Purpose of the Study:

• To synthesize poly(L-lactide)/hydroxyapatite (PLLA/HA) composites with varying HA content.
• To investigate the effect of HA incorporation on the structural, thermal, and mechanical properties of PLLA.
• To evaluate the potential of these composites as biomaterials.

Main Methods:

• Poly(L-lactide) synthesized via ring-opening polymerization.
• PLLA/HA composites prepared by blending HA particles (25-45 µm, Ca/P = 1.69) into PLLA solutions at 10, 30, and 50 wt% HA.
• Specimens fabricated using compression molding and machining.
• Characterization included scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), and mechanical property testing.

Main Results:

• SEM and TGA confirmed uniform dispersion of HA within the PLLA matrix.
• HA acted as a nucleating agent, slightly increasing the crystallinity of PLLA/HA composites with higher HA content.
• Dynamic mechanical analysis revealed no secondary relaxation below the glass-to-rubber transition temperature (60°C).
• Mechanical testing showed that increased HA content significantly improved the bending modulus and strength of the PLLA/HA composites.

Conclusions:

• PLLA/HA composites exhibit good HA dispersion and tunable mechanical properties.
• The incorporation of HA enhances the mechanical performance of PLLA, making it suitable for load-bearing biomedical applications.
• These PLLA/HA composites demonstrate promise for use in bone regeneration and orthopedic implants.