—
Lignin
Glass Transition (Tg)
90–170 °C
Melting Point (Tm)
— (decomposes)
Density
1.30–1.40 g/cm³
CAS Number
9005-53-2
Recycling Code
None
Category
Natural
Repeat Unit
–[C₉H₁₀O₂(OCH₃)ₓ]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
Second most abundant biopolymer and the largest renewable source of aromatics; highly heterogeneous structure limits reproducibility; a major pulp-industry by-product.
Applications
Carbon-fibre precursor, bio-phenolic resins, UV-blocking filler, dispersants.