Unitrex Lf20 – Replacement for PCTFE and Vespel SP-1 for many demanding applications?
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.
PTFE Filled PEEK vs. PTFE Filled Acetal
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 Acetal counterpart due to PEEK having a far better range of chemical resistance to aqueous and organic environments as well as acids and alkalines. Acetal Copolymer 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. DupontGoogle+ – Hayden Hess