Mg alloy rod reinforced biodegradable poly-lactic acid composite for load bearing bone replacement

Absorbable medicinal devices must be fabricated in order to have a suitable degradation rate in agreement with the healing rate of bone in the implantation site. In this work one of the naturally biodegradable poly-lactic acids composite reinforced with (AZ31) magnesium alloy rod for potential application and there in-vitro degradation is investigated during 8 weeks. There microstructures, mechanical properties, immersion corrosion and surface/interface behavior were studied. Fluoride conversion coatings formed porous MgF2 ceramic layer on Mg rod surface. The results show that the Mg rod reinforced poly-lactic acid plays a crucial role in the degradation rate of PLA/Mg composite, treated with hydrofluoric acid promoting a lower degradation rate than untreated sample. This fact is only due to micro-anchoring effect, leading to better mechanical properties and degradation performance in simulated body fluid solution. Untreated promote a faster formation of cracks and, therefore, an increasingly faster degradation of the polymeric matrix. With prolonging immersion time until 8 weeks, the MgF2 porous coatings were corroded gradually, along with the disappearance of original pores and the formation of a relatively smooth surface. It resulted in a rapid reduction in mechanical properties for corresponding composite rods owing to the weakening of interfacial binding capacity between poly-lactic acid and inner layer. The present results indicated that this new Mg alloy rod reinforced poly-lactic acid composite rods show a potential for biomedical applications.