Uniaxial Draw Of Poly(aryl‐ether‐ether‐ketone) by solid‐state extrusion

Poly(aryl‐ether‐ether‐ketone) (PEEK) films and rods have been solid‐state extruded at 154 and 310°C, respectively. The crystal orientation functions, melting behavior, density, and tensile properties of the drawn PEEK films (EDR ≤ 3.7) and rods (EDR ≤ 5.5) have been measured. As extrusion draw ratio (EDR) was increased, the c ‐axis orientation function, melting temperature, and tensile modulus and strength increased. Moduli up to 6.5 GPa and the strengths up to 600 MPa, 3 and 6 times the values of undrawn films, respectively, were obtained for the drawn films. The thermal expansivities along (α ‖ ) and perpendicular (α ⟂ ) to the draw direction of PEEK rods were measured from −40 to +10°C. As EDR was increased, α ⟂ increased, but α ‖ decreased. At EDRs of 3.8 and 5.5, α ‖ even exhibited negative values (about −5 × 10 −6 °C −1 ), probably due to reversible contraction of elongated tie‐molecules.