PEN (Polyethylene Naphthalate) High-Performance Fibre
topic
PEN (polyethylene naphthalate): naphthalene ring instead of benzene ring in backbone. Higher chain stiffness → higher Tg (120°C vs. 67°C), higher modulus (250 cN/dtex vs. 120), better thermal stability, and superior UV/barrier resistance compared to PET. Used for: industrial tyre cord, magnetic tape base, electronic substrates. More expensive than PET (naphthalene feedstock from coal tar). Not widely used in apparel.
Role
PEN illustrates how aromatic ring geometry (naphthalene vs. benzene) profoundly affects chain stiffness, thermal transitions, and modulus — making it an important case study in structure–property relationships in high-performance polyesters.