Investigation of mechanical integrity and high-cycle fatigue behavior of 3D-printed PLA/PCL blend after exposure to a physiological environment

Polylactic-Acid/Polycaprolactone blends are promising biopolymers to be used in bioabsorbable implants, offering a range of mechanical properties which could be tailored according to their final applications. This study investigates the corrosion behavior, tensile properties, and high cycle fatigue performance of 3D-printed PLA/20 %PCL specimens after immersion in simulated body fluid (SBF), a solution that mimics the ionic composition of human plasma to simulate in vivo degradation, for different durations including 2, 4, 6, and 8 weeks. After 8 weeks of immersion in SBF, pure PLA and PLA/20 %PCL respectively exhibited a weight loss of 1.68 % and 4.33 %, a pH decreases of 18.9 % and 24.3 %, and a water uptake increase of 12.2 % and 16.7 %. Furthermore, ultimate tensile strength (UTS), which represents the maximum stress a material can withstand before failure, decreased by 41 % and 36 %, and Young's Modulus reduced by 45 % and 20 % in the pure PLA and PLA/20 %PCL specimens, respectively. After 2, 4, 6 and 8 weeks of immersion, the fatigue limit of the pure PLA respectively decreased by 3 %, 3.8 %, 6.2 %, and 10 %. However, after similar immersion times, PLA/20 %PCL blend showed larger reductions of 3.7 %, 10.3 %, 15.4 %, and 31.8 %, respectively. Despite the steeper decline in fatigue performance, of the PLA/20 %PCL blend, still exhibited a higher fatigue limit after 8 weeks of immersion, compared with that of the corroded pure PLA. This improved fatigue behavior of the PLA/PCL blend could be attributed to its superior toughness and, higher maximum elongation, suggesting its potential as a promising candidate for temporary orthopedic implants.