Comparison
PET Fiber Grade vs PEEK
A side-by-side comparison of Polyethylene Terephthalate for Fiber Applications and Polyether Ether Ketone.
Physical
Density
1.30-1.39 g/cm³
1.32 g/cm³
Water Absorption (24h)
0.1-0.5 %
0.15 %
Transparency
Can be opaque or clear (before spinning)
Opaque (amber)
Shrinkage
0.5-1.5 %
1.1 – 1.4 %
Mechanical
Young's Modulus
2.5-4.0 GPa
3.6 GPa
Tensile Strength
50-70 MPa
100 MPa
Elongation at Break
10-50 %
50 %
Impact Strength (Izod)
30-60 J/m
55 J/m
Flexural Strength
—
170 MPa
Thermal
Glass Transition Temperature
65-85 °C
143 °C
Melting Point
250-260 °C
343 °C
Continuous Service Temperature
Up to 150 °C (intermittent)
260 °C
Heat Deflection Temperature
60-70 °C
160 °C
Electrical
Dielectric Constant
3.0-3.2
3.2
Volume Resistivity
10¹²-10¹⁴ Ω⋅cm
10¹⁶ Ω·cm
Dielectric Strength
15-25 kV/mm
—
Chemical resistance
Acids
Good resistance to dilute acids
Excellent
Bases
Poor resistance to strong bases
Excellent
Solvents
Insoluble in most solvents, but can be attacked by strong acids, bases, and chlorinated hydrocarbons
Excellent
UV Resistance
Fair (requires stabilization)
Fair
Hydrolysis (steam)
—
Excellent
Sustainability
Recyclability
Highly recyclable
Recyclable (specialty)
Recycling Code
1 (PET)
7
Carbon Footprint
Moderate
~30 kg CO₂e / kg