Crucial Differences in
the Hydrolytic Degradation
between Industrial Polylactide and Laboratory-Scale Poly(L-lactide)
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Abstract
The rate of degradation of large-scale synthesized polylactide
(PLA) of industrial origin was compared with that of laboratory-scale
synthesized poly(L-lactide) (PLLA) of similar molar mass.
The structural discrepancy between the two material types resulted
in a significant difference in degradation rate. Although the hydrolysis
of industrial PLA was substantially faster than that of PLLA, the
PLA material became less brittle and fragmented to a lesser extent
during degradation. In addition, a comprehensive picture of the degradation
of industrial PLA was obtained by subjecting different PLA materials
to hydrolytic degradation at various temperatures and pH’s
for up to 182 days. The surrounding environment had no effect on the
degradation rate at physiological temperature, but the degradation
was faster in water than in a phosphate buffer after prolonged degradation
at temperatures above the <i>T</i><sub>g</sub>. The degree
of crystallinity had a greater influence than the degradation environment
on the rate of hydrolysis. For a future use of polylactide in applications
where bulk plastics are generally used today, for example plastic
packages, the appropriate PLA grade must be chosen based on the conditions
prevailing in the degradation environment
