Hydrolysis is one of the main characteristics of PLA. It affects not
only the biodegradation but also the mechanical property, which
determines the service life of PLA [4e6]. Therefore, a tremendous
amount of work has been done to study the hydrolysis of PLA. Both
chain end scission and random chain cleavage for PLA hydrolysis
have been reported in previous work though the scission kinetic
constant of the terminal groups was found to be larger than that of
the internal esters [7e10]. The carboxylic end groups following the
chain scission are known to act catalytically, leading to accelerated
hydrolysis of PLA [11,12]. Moreover, caused by the autocatalysis of
carboxyl end group, hydrolysis acts fast inside than at the surface
[13]. Therefore, the hydrolysis behavior is related to the size of PLA
and the bulk erosion mechanism is dominant [14e16]. For the
crystalline PLA, the chain cleavage proceeds preferentially in the
amorphous regions due to its good water permeability [17]. The
hydrolysis is dependent of various factors, such as chemical structure,
morphology, hydrolysis conditions [4].