In Vitro Degradation Effects on Strength, Stiffness, and Creep of PLLA/PBS: A Potential Stent Material

Abstract

Poly(L-lactic acid) is prominent in biodegradable stent material research but its brittleness is a disadvantage. Poly(butylene succinate) (PBS) addition enhances ductility but there is a void in knowledge of degradation effects on PLLA/PBS blends—vital for evaluation of a potential stent material. Neat PLLA and melt-blended PLLA/PBS specimens were subjected to tensile testing, before and after degradation in buffered saline (37°C, pH 7.4), for up to 24 weeks. Additional specimens were subjected to constant-load creep tests. Tensile test results indicate that PLLA/PBS blends exhibit gradual losses of strengths and Young's moduli as they degrade whilst neat PLLA shows little change over a 24-week degradation period. Neat PLLA exhibits increasing creep resistance during the first eight weeks of degradation whilst the 75/25 wt% PLLA/PBS blend exhibits decreasing creep resistance with increasing degradation time. PLLA/PBS blends are ductile but creep resistance during degradation needs improvement for their use as biodegradable stent materials.