Conclusions
The main degradation mechanism of PLA exposed to
photooxidation under outdoor-representative conditions was
investigated and showed polymer degradation by the formation
of anhydride groups. A mechanism based on -elimination from
hydroperoxides formed on the tertiary carbon atom of PLA is
proposed. The rapid consumption of a clay organic modifier is
the first direct evidence of the photodegradation activity of
Figure 10. FTIR spectrum of PLACl20A vs photooxidation time.
Figure 11. Evolution of 1845 cm-1 anhydride peak vs time.
Figure 12. Photocatalytic decomposition of hydroperoxides by transition
metal ions: Transition metal ion catalyzes the hydroperoxide
decomposition.
2924 Biomacromolecules, Vol. 11, No. 11, 2010 Bocchini et al.