Mechanical and degradation properties of biodegradable Mg strengthened poly-lactic acid composite through plastic injection molding

• Full biodegradable Mg alloy strengthened PLA composite rods were prepared by plastic injection molding.
• Uncoated, AO and MAO coated Mg rods were selected as insert to prepare PLA composite rods.
• Interfacial bonding force between PLA and Mg plays a very important role in PLA/Mg composite rods.
• Porous MgO coating improved the mechanical properties of composite rods by mechanical locking and chemical bonding.

Full biodegradable magnesium alloy (AZ31) strengthened poly-lactic acid (PLA) composite rods for potential application for bone fracture fixation were prepared by plastic injection process in this work. Their surface/interfacial morphologies, mechanical properties and vitro degradation were studied. In comparison with untreated Mg rod, porous MgO ceramic coating on Mg surface formed by Anodizing (AO) and micro-arc-oxidation (MAO)treatment can significantly improve the interfacial binding between outer PLA cladding and inner Mg rod due to the micro-anchoring action, leading to better mechanical properties and degradation performance of the composite rods.With prolonging immersion time in simulated body fluid (SBF) solution until 8 weeks, the MgO porous coating were corroded gradually, along with the disappearance of original pores and the formation of a relatively smooth surface. This resulted in a rapidly reduction in mechanical properties for corresponding composite rods owing to the weakening of interfacial binding capacity. The present results indicated that this new PLA-clad Mg composite rods show good potential biomedical applications for implants and instruments of orthopedic inner fixation.

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