Unfilled PET
Unfilled PET is a grade of PET. It has the lowest strength and highest ductility compared to the other variants of PET. The graph bars on the material properties cards below compare unfilled PET to: polyester plastics (top), all thermoplastics (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Elastic (Young's, Tensile) Modulus
3.5 GPa 0.51 x 106 psi
Elongation at Break
70 %
Impact Strength: Notched Izod
43 J/m 0.8 ft-lb/in
Poisson's Ratio
0.39
Tensile Strength: Ultimate (UTS)
60 MPa 8.7 x 103 psi
Thermal Properties
Glass Transition Temperature
70 °C 160 °F
Heat Deflection Temperature At 1.82 MPa (264 psi)
80 °C 180 °F
Heat Deflection Temperature At 455 kPa (66 psi)
120 °C 240 °F
Maximum Temperature: Autoignition
410 °C 760 °F
Maximum Temperature: Decomposition
390 °C 730 °F
Maximum Temperature: Mechanical
80 °C 180 °F
Melting Onset (Solidus)
260 °C 490 °F
Specific Heat Capacity
1150 J/kg-K 0.27 BTU/lb-°F
Thermal Conductivity
0.2 W/m-K 0.12 BTU/h-ft-°F
Thermal Expansion
70 µm/m-K
Electrical Properties
Dielectric Constant (Relative Permittivity) At 1 Hz
3.7
Dielectric Strength (Breakdown Potential)
50 kV/mm 2.0 V/mil
Electrical Resistivity Order of Magnitude
13 10x Ω-m
Otherwise Unclassified Properties
Density
1.4 g/cm3 86 lb/ft3
Limiting Oxygen Index (LOI)
21 %
Water Absorption After 24 Hours
0.1 %
Water Absorption At Saturation
0.5 %
Common Calculations
Stiffness to Weight: Axial
1.4 points
Stiffness to Weight: Bending
37 points
Strength to Weight: Axial
12 points
Strength to Weight: Bending
25 points
Thermal Diffusivity
0.13 mm2/s
Thermal Shock Resistance
17 points
Followup Questions
Further Reading
SPI Plastics Engineering Handbook of the Society of the Plastics Industry, Inc., 5th ed., Michael L. Berins (editor), 2000
Modern Plastics Handbook, Charles A. Harper (editor), 1999
Plastics Materials, 7th ed., J. A. Brydson, 1999