PolyLactic

Polylactic acid, commonly abbreviated PLA, is a biodegradable aliphatic polyester used in packaging, medical devices, and 3D printing. It is produced from lactic acid and exists in stereoisomeric forms: poly-L-lactic acid (PLLA), poly-D-lactic acid (PDLA), and poly(D,L-lactic acid) (PDLLA).

PLA is typically made by polymerizing lactide, a cyclic diester of lactic acid, through ring-opening polymerization. Lactic acid is usually obtained by fermentation of sugars from corn, sugarcane, or other feedstocks. Common catalysts include tin(II) octoate and other metal catalysts. PLA is thermoplastic with a glass transition around 55-65 C and a melting point of 150-160 C; crystallinity and properties vary with stereochemistry.

Applications include food packaging, films, and disposable tableware, as well as medical implants, sutures, and drug-delivery systems, due to biocompatibility and biodegradability. It is also widely used in additive manufacturing as a filament for fused deposition modeling because of its ease of processing and relatively low odor.

PLA is derived from renewable resources, contributing to lower net greenhouse gas emissions compared with many petroleum-based plastics. It is compostable under industrial conditions, breaking down to water, carbon dioxide, and biomass; home composting is usually ineffective. Recycling is possible but less common, with mechanical and chemical routes facing challenges from contamination and limited infrastructure.

Limitations include moderate heat resistance, brittleness, and cost. Blending or copolymerization can improve toughness and heat resistance. PLA's performance depends on crystallinity and molecular weight, and it requires suitable end-of-life facilities to realize its environmental benefits.