Oxidative degradation of polylactide (PLA) and its effects on physical and mechanical properties

The thermo-oxidative degradation of polylactide (PLA) films was studied between 70 and 150 degrees C. It was shown that the oxidative degradation of PLA leads to a random chain scission responsible for a reduction of the molar mass. These molar mass changes affect T-g and the degree of crystallinity, and it was found that T-g decreases according to the Fox-Flory theory whereas the degree of crystallinity increases due to a chemicrystallization process. A correlation between molar mass and strain at break during oxidation has been established: PLA displays a brittle behavior when M-n falls below 40 kg mol(-1) in agreement with relationships linking the critical value for embrittlement with the molar mass between entanglements. (C) 2013 Elsevier Ltd. All rights reserved.