PHB
Polyhydroxybutyrate
Glass Transition (Tg)
0–5 °C
Melting Point (Tm)
170–180 °C
Density
1.25 g/cm³
CAS Number
29435-48-1
Recycling Code
♺ 7
Category
Biodegradable
Repeat Unit
–[O–CH(CH₃)–CH₂–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
Produced directly by bacteria as an energy store; truly marine-biodegradable; highly crystalline and therefore very brittle, with a narrow processing window (Tm close to degradation).
Applications
Compostable packaging, agricultural films, medical devices.