Mechanical Behavior of Poly(Ethylene 2,6-Naphthalene-Dicarboxylate) (PEN) Fibres near the Glass-Rubber Transition Temperature

Abstract

The mechanical properties of as-spun poly(ethylene 2,6-naphthalene-dicarboxylate) (PEN) fibres were studied in order to characterize this relatively new material near its glass-rubber transition.

Tensile tests were carried out on amorphous (low-speed spun) PEN filaments. The temperature range of 90°C up to 160°C was covered using increments of 10°C. A transition from necking and cold drawing to rubber-like behavior was observed in the stress-strain relationship. Dynamic mechanical experiments were carried out on PEN yarns spun at speeds from 500 to 4000 m min⁻¹. Both temperature and frequency were varied. The maxima in loss modulus depend on spinning speed. Tensile behavior and dynamic mechanical behavior of PEN fibres demonstrate that the glass-rubber transition temperature of PEN is approximately 125°C.

Key Words:

• PEN
• glass temperature transition
• polyester fibre.