Mylar® is a Polyester Film and is registered trademark owned by Dupont Tejjin Films.  Mylar is wear resistant, durable and strong and suitable for many applications.

What are the Highlights of Mylar Plastic Fasteners?

Mylar is:

  • AN extremely good electrical insulator
  • Less expensive and an alternative to Kapton
  • Dimensionally stable

Additionally, mylar fasteners exhibit low shrinkage, exhibit low moisture absorption characteristics, have good dielectric properties and include high thermal resistance.

Mylar WasherIn which applications can you use Mylar within Plastic Fasteners?

A very popular use for Mylar within plastic fasteners is mylar washers.   Mylar washers have a number of uses, including:

  • As a plastic washer (this is the most popular option for Mylar).
  • As a plastic spacer
  • To reduce vibration vs. metal substitutes
  • As a locking device
  • For load distribution for certain fasteners like screws and bolts

Mylar washers can also be die cut into many sizes, and from materials such as nylon, Teflon, vulcanized fiber, polyethylene, Lexan, cork, felt, neoprene and others.

Physical and Thermal Properties

Mylar ® polyester film retains good physical properties over a wide temperature range (–70 to 150 ° C [–94 to 302 ° F]), and it is also used at temperatures from –250 to 200 ° C (–418 to 392 ° F) when the physical requirements are not as demanding

Shear Strength

Mylar ® has a shear strength that is significantly higher than published data for other polymeric materials such as acetals, nylons, and polyolefins.

Thermal Expansion

The thermal coefficient of linear expansion of Mylar ® is 1.7 × 10 –5 in/in/ ° C (9.5 × 10 –6 in/in/° F).


Mylar ® is unusually resistant to creep. Two values measured at room temperature are 0.1% after 260 hr at 2.09 kg/mm 2 (2.98 kpsi) and 0.2% after 1000 hr at 2.10 kg/mm 2 (3.00 kpsi). After 4000 hr at 0.35 kg/mm 2 (0.50 kpsi) in 100 ° C (212 ° F) oven, a creep of 0.9% was measured.

Heat Aging

The maximum service temperature usually recommended for Mylar polyester film is 150°C (302°F). Where extensive exposure, severe environmental conditions, or unusual physical requirements are involved, it may be necessary to reduce service temperatures. However, coatings are available to increase the resistance of Mylar® to the effects of heat aging.


When choosing components and fasteners for manufacturing and production, it’s important to consider the application, the environment of the finished products and the characteristics of the materials available. Plastics, and especially some of the advanced composite materials, make a great choice for many applications and offer exceptional strength and resistance to wear.

Mylar  is a very popular choice within a wide variety of plastic fasteners, but it’s not used in every application.  If you have any questions on the properties of nylon plastic fasteners, or its use within your application, please do not hesitate to contact us.  We’re here to help!