PAA
Polyacrylic Acid
Glass Transition (Tg)
~105 °C
Melting Point (Tm)
— (amorphous)
Density
1.22 g/cm³
CAS Number
9003-01-4
Recycling Code
None
Category
Functional & Smart
Repeat Unit
–[CH₂–CH(COOH)]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
Weak polyelectrolyte: ionises above pH ~4.5 and the chain expands by charge repulsion; crosslinked sodium salt absorbs hundreds of times its weight in water.
Applications
Superabsorbent in diapers (SAP), thickeners, dispersants, mucoadhesives.