PLA
Polylactic Acid
Glass Transition (Tg)
55–60 °C
Melting Point (Tm)
150–175 °C
Density
1.24–1.27 g/cm³
CAS Number
26100-51-6
Recycling Code
♺ 7
Category
Biodegradable
Repeat Unit
–[O–CH(CH₃)–CO]ₙ–
The repeating unit is the smallest structural fragment whose repetition builds the whole chain. Subscripts show the relative share of each unit in copolymers.
Key Properties
Made from fermented corn or sugarcane; stereochemistry (L/D ratio) controls crystallinity — PLLA crystallises, while >10 % D-units give a fully amorphous resin; industrially compostable but brittle with low HDT.
Applications
3D-printing filament, food packaging, resorbable sutures and screws.