The solid symbols stand for the crystallinity obtained during
hydrolysis, which is calculated based on the first heating scan
(Fig. 7c). The crystallinity of each sample shows an evident increase
from 3% to 35% after 2 days immersion in water, which results in
surface whitening and complete loss of transparency. This may be
caused by the enhancement of PLA segments mobility by the high
temperature and plasticizing effect of water. The following increase
in crystallinity may be mostly related to the loss of amorphous PLA
because the hydrolysis is easier occurred in amorphous [17,30].