Morgan Deroiné, Antoine Le Duigou, Yves-Marie Corre, Pierre-Yves Le Gac, 
Peter Davies, Guy César, Stéphane Bruzaud, Accelerated ageing of 
polylactide in aqueous environments: Comparative study between distilled 
water and seawater, Polymer Degradation and Stability, Available online 
23 January 2014, ISSN 0141-3910, 
http://dx.doi.org/10.1016/j.polymdegradstab.2014.01.020.
(http://www.sciencedirect.com/science/article/pii/S0141391014000226)
Abstract: Pollution of nature by plastics is a major environmental 
problem and the challenge for the future is to manage the lifetime of 
polymers better. The aim of this study is to establish a baseline on 
degradation mechanism and degradation kinetics for lifetime prediction 
of polylactide (PLA) in a marine environment. The ageing of PLA was 
accelerated by raising temperature in distilled water, filtered and 
renewed seawater and natural seawater. Samples were immersed in 
distilled water for six months at different temperatures (25, 30, 40 and 
50°C) in order to evaluate the influence of temperature on PLA 
degradation kinetics and to predict lifetime. Then, samples were 
immersed in seawater both in the laboratory and at sea, in order to 
compare the effects of environment, marine organisms and salt, on 
degradation. The different degradation steps were followed by 
gravimetry, tensile tests, scanning electron microscopy (SEM), steric 
exclusion chromatography (SEC) and differential scanning calorimetry 
(DSC). In distilled water, accelerated ageing of PLA is complex with 
deviation from Fickian behaviour at higher temperature. Moreover, 
immersion in distilled water induces morphological changes, in 
particular holes, which are absent in seawater at 40°C for the same 
immersion time. Indeed, seawater has little impact on the diffusion 
kinetics but affects M∞ values, which are slightly lower compare to the 
distilled water uptake.
Keywords: PLA; accelerated ageing; hydrothermal ageing; degradation