Tough polylactide blend system for osteosynthesis procedures

This work stems from the need to contribute, improve and collaborate in the design of new bioresorbable polymeric implants for bone fracture fixations (osteosynthesis procedures), particularly those involving polylactides (PLA). Choosing materials for orthopedic implants often imposes strict requirements for the mechanical properties. PLA is widely employed for this purpose; however toughening schemes are necessary for its suitable application. Blending of poly(D, L-lactide) (PDLLA) and biodegradable poly(L-lactide-co-ε-caprolactone) copolymer (PLCL) showing a thermoplastic-elastomeric behavior has been performed in an effort to toughen the PDLLA without compromising its biodegradability and biocompatibility. The miscibility state of PDLLA/PLCL blend system is studied by means of Differential Scanning Calorimetry (DSC), phase morphology is observed by Scanning Electron Microscopy (SEM) and eventually, the changes in mechanical properties during the first 3 months at body temperature is also discussed to establish a preliminary outline of the response that could be expected from this system in service. Blends of PDLLA/PLCL show two clear Tg indicating immiscibility of the blends. The phase separation is also corroborated by SEM micrographs where two distinct phases are observed clearly, one acting as a matrix and the other one as a dispersed phase. Initially, the toughness of PDLLA was considerably improved by the addition of PLCL. The elongation at break was significantly increased. However, the mechanical properties loss during the aging at body temperature of the blends indicates the unsuitability of these blends to use as bone fracture fixations.