The metal-catalyzed reaction tends to cause racemization of the PLA, reducing its stereoregularity compared to the starting material (usually corn starch). The most common route to PLA is the ring-opening polymerization of lactide with various metal catalysts (typically tin octoate) in solution or as a suspension. Two main monomers are used: lactic acid, and the cyclic di-ester, lactide. Several industrial routes afford usable (i.e. The monomer is typically made from fermented plant starch such as from corn, cassava, sugarcane or sugar beet pulp. The name "polylactic acid" is potentially ambiguous or confusing, because PLA is not a polyacid ( polyelectrolyte), but rather a polyester. Without annealing, however, PLA has the lowest heat resistance of the common 3D printing plastics.Īlthough the name "polylactic acid" is widely used, it does not comply with IUPAC standard nomenclature, which is "poly(lactic acid)". Its low melting point, high strength, low thermal expansion, good layer adhesion, and high heat resistance when annealed make it an ideal material for this purpose. PLA is the most widely used plastic filament material in 3D printing. Its widespread application has been hindered by numerous physical and processing shortcomings. In 2021, PLA had the highest consumption volume of any bioplastic of the world, although it is still not a commodity polymer. PLA has become a popular material due to it being economically produced from renewable resources. It can also be prepared by ring-opening polymerization of lactide [–C(CHĢ, the cyclic dimer of the basic repeating unit. N, formally obtained by condensation of lactic acid C(CHģ)(OH)HCOOH with loss of water (hence its name). Polylactic acid, also known as poly( lactic acid) or polylactide ( PLA), is a thermoplastic polyester with backbone formula (C
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