PPTA
Para-aramid (Kevlar)
Glass Transition (Tg)
—
Melting Point (Tm)
~500 (decomposes) °C
Density
1.44 g/cm³
CAS Number
24938-64-5
Recycling Code
♺ 7
Category
High-Performance
Repeat Unit
–[NH–C₆H₄–NH–CO–C₆H₄–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
Rigid para-linked backbone with dense hydrogen bonding forms highly oriented fibres; specific strength ~5× steel; degraded by UV and strong acids.
Applications
Ballistic vests, cut-resistant gloves, tyre reinforcement, ropes.