Polyethylene Naphthalate ( PEN ) - Data Supplied by Goodfellow

Background

Polyethylene Naphthalate is a polyester that is chemically quite similar to polyethylene terephthalate but which is more temperature resistant. So far available only as biaxially oriented and heat stabilised films, they are semi-crystalline and colourless, either crystal clear or slightly hazy (the latter are available from Goodfellow stock).

Compared to their polyethylene terephthalate equivalents, they start to shrink significantly at 190 °C rather than 150 C and are certified for long term electrical use at 155 °C rather than 105/130 °C. Their tensile strengths are similar, but the modulus of Polyethylene Naphthalate is higher - say 25% at ambient temperatures but several times higher in the 100-150 °C region.

They also have better UV resistance and barrier properties and are more resistant to hydrolysis in alkaline or very hot aqueous conditions. Polyethylene Naphthalate films are, however, more expensive and have a lower flex life.

Applications

Applications for the Polyethylene Naphthalate films are mainly in the electrical and electronic areas.

Properties

The key properties of Polyethylene Naphthalate are tabulated below.

Table 1. Key properties

Chemical Resistance
Acids - concentrated Poor - Good
Acids - dilute Good
Alcohols Good
Alkalis Poor - Good
Aromatic hydrocarbons Good
Greases and Oils Good
Ketones Good
Electrical Properties
Dielectric constant @ 1 MHz 3.2 @ 10 kHz
Dielectric strength ( kV.mm-1 ) 160 @ 0.075 mm
Dissipation factor @ 1 MHz 0.0048 @ 10 kHz
Surface resistivity ( ohm/sq ) 1014
Volume resistivity ( ohm.cm ) 1015
Mechanical Properties
Coefficient of friction 0.27 - biax film
Elongation at break ( % ) 60 - biax film
Tensile modulus ( GPa ) 5-5.5 - biax film
Tensile strength ( MPa ) 200 - biax film
Physical Properties
Density ( g.cm-3 ) 1.36
Flammability VTM-2 - UL94, 0.075 mm
Optical transmission ( % ) 84 @ 0.075 mm
Thermal Properties
Coefficient of thermal expansion ( x10-6 K-1 ) 20-21 - biax film
Upper working temperature ( °C ) 155
Properties Polyethylene naphthalate Film
Property Value
Shrinkage % 0.8 – 5 min @ 190 °C

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Source: Goodfellow

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