PLA Photooxidation. The infrared analysis of PLA photooxidation
shows the formation of a band with a maximum at
1845 cm-1 (Figure 5), attributed to the formation of anhydride
groups.42 In the hydroxyl region, a broad absorption band is
observed with a maximum at 3400 cm-1 that corresponds to
products such as hydroperoxides or alcohols.
Anhydride presence was confirmed by exposition of the
photooxidated film to NH3 saturated atmosphere. Infrared
analysis of exposed films shows the disappearance of the 1845