PEN
Polyethylene Naphthalate
Glass Transition (Tg)
120–125 °C
Melting Point (Tm)
265–270 °C
Density
1.36 g/cm³
CAS Number
24968-11-4
Recycling Code
♺ 7
Category
Engineering
Repeat Unit
–[O–CH₂CH₂–O–CO–C₁₀H₆–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
Naphthalene ring gives higher Tg, better barrier and UV blocking than PET; significantly more expensive.
Applications
Hot-fill bottles, flexible electronics substrates, high-grade films.