Effect of unidirectional drawing process on fracture behavior of poly(l-lactide)

Excerpt

Poly(l-lactide) (PLLA) has widely been used as a polymeric biomaterial mainly owing to its bioabsorbability and biocompatibility. For example, PLLA has successfully been used for bone fixation devices in oral and orthopedic surgeries [1]. Although application of PLLA medical devices is rapidly growing, the deformation and fracture behavior of PLLA has not fully been understood yet. Fundamental mechanical properties of thin PLLA films have already been evaluated [2‐5]; however, few studies have performed to understand such properties of bulk sheet samples. Recently, Todo et al. have extensively investigated the fracture properties and behavior of PLLA plate specimens [6‐11], and clarified the effects of annealing, crystallization, hydrolysis and loading-rate on the fracture behavior. Drawing process is known to be an effective way to improve the mechanical properties of thermoplastics, and effects of drawing on tensile and fracture properties of thermoplastics have been studied [12‐16]. PLLA is usually draw-processed when it is used for bone fixation devices, and therefore, fundamental effect of drawing on its fracture behavior needs to be characterized. …