Ageing of different biodegradable polyesters blends mechanical and hygrothermal behavior

The aim of this study is to better understand the performance of binary blends of biodegradable polyesters when exposed to hygrothermal ageing, in order to overcome some of their limitations such as water resistance. For this, blends have been prepared by extrusion using two P(L)LA (l-poly-(lactic acid)) of different molecular weights and PɛCL (poly-ɛ-caprolactone). Mechanical properties over ageing are reported and compared to pure P(L)LA. Blending PɛCL to P(L)LA allowed to improve P(L)LA initial resilience. During ageing, crystallinity increase seemed to lower water uptake at short ageing times, while osmotic cracking was found to possibly occur in pure P(L)LA for long ageing times, thus increasing water uptake. Besides, P(L)LA/PɛCL blends water uptake remained constant over ageing. Finally, while P(L)LA resilience decrease could be related to chain scission, blend aptitude to elongation decrease was related to interphase decohesion, at long ageing times. Results showed P(L)LA molecular weight influence on both initial mechanical properties and water uptake.