A.17.14. PETP (Mylar, Melinex, Terphane, ...)

PRODUCT

Type

Thermoplastic film.

Chemical Composition

Polyethylene Terephthalate.

Manufacturer

Several (DuPont USA, ICI UK, La Cellophane France, ...)

EXPERIENCE & AVAILABILITY

Development Status

Commercial Product

Cost Range

Very Low

Lot Reproducibility

Excellent

Space Experience

Extensive

GENERAL PROPERTIES (Physical, Mechanical, Thermal, Electrical, Optical)

Nature

Typical Value

Remarks

Specific Gravity

1.4

 

Tensile Strength

210 MPa

 

Tear Strength

0.787 kg/mm

 

Folding Endurance

> 100 000

ASTM D2176

Thermal Expansion Coefficient

30 x 10-6 C -1

 

Thermal Conductivity

0.61 W m -1 C -1

 

Specific Heat

1.3 J g-1 C -1

 

Volume Resistivity

1016 W m

 

Dielectric Constant

3.2

50 Hz, 25C

Dissipation Factor

0.002

50 Hz, 25C

Dielectric Strength

280 kV/mm

 

Refractive Index

1.64

 

PROPERTIES RELEVANT TO SPACE USE

Nature

Typical Value

Type of Test

Temperature Range

-180 to +150C

Long term

Outgassing

TML = 0.3%, RML = 0.1%, CVCM = 0.03%

ECSS-Q-70-02

Oxygen Index

31

ECSS-Q-70-21

Ionising Radiation

10 Mrad

Mechanical properties

UV Radiation

Unstable

 

Water Absorption

0.6%

Immersion

Toxicity/Offgassing

Pass

NASA NHB 8060-1A

Flammability

Burnt

NASA NHB 8060-1B

SPECIAL RECOMMENDATIONS

          Aluminised films (1 or 2 faces) exist in the trade and are extensively used in space programmes since Al protects the plastic against destruction by unfiltered UV light.

          Sizes available are down to 3mm thick and up to 300 cm wide, depending on the vendor.

          Flammability depends on thickness and configuration.

          PETP is etched by atomic oxygen in low earth orbit at a rate of approx. 3.4 x 10-24 cm3/atom.