polylactaat

Polylactaat, or poly(lactic acid) (PLA), is a biodegradable aliphatic polyester produced from lactic acid. It is typically synthesized by polymerizing lactide, the cyclic di-ester of lactic acid, through ring-opening polymerization or, less commonly, polycondensation. The material exists as stereoisomers: poly(L-lactide) (PLLA), poly(D-lactide) (PDLA), and the racemic poly(D,L-lactide) (PDLLA). Copolymers and blends are used to tailor crystallinity, thermal properties, and degradation rates.

PLA is a thermoplastic with good clarity and moderate stiffness. It has a glass transition temperature around 55–60°C and a melting temperature around 150–160°C. The polymer is relatively brittle and exhibits limited heat resistance, but can be reinforced or plasticized through blends. PLA is derived from renewable resources and is typically biodegradable under industrial composting conditions, with degradation influenced by crystallinity, molecular weight, and environmental factors. It degrades mainly by hydrolysis of the ester bonds, followed by microbial assimilation.

Production begins with the fermentation of sugars to lactic acid, which is then converted to lactide and polymerized via ring-opening polymerization using catalysts such as tin(II) octoate or other metal catalysts to yield high-molecular-weight PLA. Adjusting stereochemistry, crystallinity, and copolymer composition enables a range of properties suitable for different applications.

Applications include packaging films and containers, disposable cutlery, agricultural films, 3D printing filaments, and various medical devices such as sutures and implants. PLA’s renewability and potential for lower carbon footprint contribute to its role in sustainable materials strategies, though end-of-life management depends on local composting infrastructure.