PP
Polypropylene
Glass Transition (Tg)
-10 °C
Melting Point (Tm)
160–170 °C
Density
0.90–0.91 g/cm³
CAS Number
9003-07-0
Recycling Code
♺ 5
Category
Commodity
Repeat Unit
–[CH₂–CH(CH₃)]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
Lowest density of common thermoplastics; isotactic grade is semi-crystalline; excellent fatigue resistance (living hinge); brittle below 0 °C unless impact-modified.
Applications
Automotive bumpers, food containers, BOPP film, nonwoven fabrics, medical syringes.