In terms of volume applications, the biopolyester
polylactide or PLA is arguably the biodegradable polymer
that has the greatest commercial potential. PLA is a
polymer of lactic acid and is commonly produced by
ring-opening polymerisation of the cyclic lactide dimer
[3]. PLA may also be produced by direct polycondensation
of lactic acid and although this route usually yields
fairly low molecular weight species, special procedures
can overcome this problem [4]. Lactic acid, the starting
material for PLA synthesis, can be produced by fermentation
from a number of different renewable
resources and, for example, a large PLA production
facility based on use of corn starch-derived lactic acid
and with an annual production capacity of 140,000
metric tons is currently being established in North
America by Cargill Dow LLC, a joint venture between
Cargill Corporation and Dow. A recent review article
lists a number of other current manufacturers of PLA
[5].