polyLlactic

Polylactic acid, often written as polyLlactic in some sources and commonly abbreviated PLA, is a biodegradable, bio-based aliphatic polyester derived from lactic acid or its cyclic dimer, lactide. It is produced primarily by ring-opening polymerization of lactide, although high-molecular-weight PLA can also be obtained by polycondensation of lactic acid under reduced pressure. Lactic acid is typically produced by fermentation of carbohydrate feedstocks such as corn, sugarcane, or cassava, making PLA a renewable-resource polymer.

PLA exists in three stereoforms: poly-L-lactic acid (PLLA), poly-D-lactic acid (PDLA), and the racemic poly(D,L-lactic acid) (PDLLA). Tacticity governs crystallinity, heat resistance, and mechanical behavior: PLLA and PDLA are predominantly semicrystalline; PDLLA is usually amorphous. Glass transition temperatures are around 55–65 C, while melting points for crystalline PLLA are approximately 170–180 C. These properties, along with molecular weight, influence processability by injection molding, extrusion, blow molding, and 3D printing.

Applications include packaging films and containers, agricultural mulches, and disposable cutlery, as well as medical uses such as sutures, implants, and drug-delivery systems. PLA is also popular in additive manufacturing as a filament.

Biodegradation occurs via hydrolysis of ester bonds to lactic acid; degradation is accelerated in industrial composting environments with elevated temperature and humidity. In the environment, degradation is slower and not guaranteed. Recycling is possible through mechanical recovery or chemical recycling, though PLA is often kept separate from conventional plastics.

Safety and sustainability: PLA is derived from renewable resources and generally considered biocompatible and approved for certain medical applications; life cycle assessments vary depending on feedstock and energy sources.