Unitrex Lf20 – PTFE Filled PEEK

A newly released form of Filled PEEK is now available. This PEEK is filled with PTFE and is called Unitrex Lf20, and it is filled with 20% PTFE. This new grade of PTFE Filled PEEK plastic is produced by Nytef Plastics. It is an extruded thermoplastic that comes in both rod and sheet form. This grade has significantly improved properties over the standard unfilled grades of PEEK. The PTFE filler provides excellent wear properties and has a very low co-efficient of friction, which makes this a great material for sliding and wear applications, and is made to last for long periods of abuse. Unitrex Lf20 has great machinability and dimensionally stability. It has a wide range of uses in such fields as medical, semi-conductor, and aerospace seals, where standard PEEK is too rigid. These properties enable this material to replace Polyimide (Vespel®) and PCTFE (formerly Kel-F) in many applications of high chemical resistance and the ductility for use in seals. This Filled PEEK works extremely well in Medical, Semi-Conductor and Aerospace Seal applications. Nytef Plastics Unitrex Lf20 Manufacturer

PTFE Filled PEEK vs. PTFE Filled Acetal – Delrin


Comparable to Lf13 which is 13% PTFE filled Delrin (Delrin AF), which is also good for most of the same types of applications but cannot withstand the high temperatures than that of Unitrex Lf20. The PTFE Filled PEEK has a melting point of 650 degrees F while the PTFE Filled Delrin – Unital Lf13 has a melt point of 347 degrees F, making both materials high temperature plastics.

Because the Nytef Unitrex Lf20 is filled with PTFE (which has the lowest co-efficient of friction of any plastic), it is ideal for sliding and wear applications. It also has a kinetic and static friction resistance of 0.1 which makes it the perfect choice for jobs were heat from friction should not be generated and part longevity is critical. Unitrex Lf20 offers superior properties to many other plastics, such as high heat and chemical resistance but also great friction resistance along with improved properties to make it a great plastic for a wide spectrum of uses.

Why Change from Vespel SP-1 or PCTFE to Unitrex Lf20?

While this new PTFE Filled PEEK will not replace the Vespel SP-1 and PCTFE in all applications, it certainly will in many applications (see table for comparison). The main reason to make a change is, drum roll please, COST. The Unitrex Lf20 is up to 30% less expensive that the other materials. With similar and comparable properties, consider making the change.

Unitrex Lf20 also exhibits a far superior chemical resistance to that of its Delrin counterpart due to PEEK having a far better range of chemical resistance to aqueous and organic environments as well as acids and alkalines. Delrin tends to degrade when exposed to such chemicals like sulfuric acid and chlorine while PEEK only tends to be attacked by halogens and hydrocarbons such as in crude oils. For additional properties and to compare the Unitrex LF-20 to Dupont Vespel SP-1 and PCTFE see the table below. Here is a copy of the full data sheet on Nytef Unitrex Lf20.


Standard Properties Table

Properties TestMethod Unit UnitrexLF20 Nominal Value PCTFE(Kel-f) Nominal Value VespelSP-1 Nominal Value
Specific Gravity ASTM-D-792 1.42 2.1 – 2.14 1.43
Tensile Strength ASTM-D-638 psi 11,500 4,800 – 5,300 12,500
Tensile Modulus ASTM-D-638 psi 460,000 207,000
Flexural Modulus ASTM-D-790 psi 500,000 180,000 450,000
Rockwell Hardness ASTM-D-785 84-D 90-D 45 – 60 E
Melting Point DSC degress F 650 410 – 415 680+
Flammability UL 94 @ 3.0mm V-0 V-0 V-0
Kinetic Coef. of Friction ASTM-D-1894 0.1
Static Coef. of Friction ASTM-D-1894 0.1

For additional details on these and other materials, please contact us here or call us at 866-832-9315

Unitrex and Unital are registered trademarks of Nytef Plastics, Ltd.
Nytef is a US manufacturer of plastic sheet and rod, is based in Bensalem, PA
Delrin and Vespel are registered trademarks of E.I. Dupont

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