What Makes PCTFE Unique?
The challenged supply chain has surfaced several products that are often overlooked as they are not used in high volumes; however, they become critical pain points upon lack of availability. One such product is PCTFE. A practical comparison is to compare PCTFE (Poly-Chloro-Tri-Fluoro-Ethylene) to PTFE (Poly-Tetra-Fluor-Ethylene), the workhorse of the fluoropolymer family.
At first glance, the formula is exactly the same, except for one Fluorine atom on the PTFE molecule converted to a Chlorine atom. However, it seems like a minute change; the addition of the chlorine atom results in a huge difference in the final properties of the material.
Chemical Resistance
PTFE is a fully fluorinated molecule and thus is practically inert to chemical attack even in strong acids. PCTFE being partially fluorinated but containing 3 of 4 Fluorine atoms on the polymer results in a very good chemical resistance but not to the high standards of PTFE, specifically in aromatic and halogenated solvents.
Mechanical Properties
When high voltages, extreme chemical resistance, and high thermal properties are required, more often, PTFE becomes a default product. However, where high dimensional stability over a wide temperature range is needed, or high mechanical strength is required, PTFE may not fit the application. PCTFE offers approximately 2X higher tensile strength, substantially less elongation, and 2.5X tensile modulus.
Thermal Properties
The addition of the chlorine atom reduces the melting point of PCTFE to 410°F compared to the 621°F achieved with the PTFE. It needs to be considered for your application.
Bottom Line
PCTFE occupies a unique niche between Advanced Engineered Polymers such as PEEK or PPS & PTFE in terms of dimensional stability but still offers phenomenal properties. In addition, PCTFE offers extremely low outgassing values with the low flammability of a fluoropolymer.
Comparison Table
| Property | PTFE (Virgin) | PCTFE |
|---|---|---|
| Tensile Strength (ASTM D638, psi) | 3,600 | 7,830 |
| Tensile Modulus (ASTM D638, psi) | 80,000 | 218,000 |
| Flexural Modulus (ASTM D790, psi) | 72,000 | 220,000 |
| Chemical Resistance | Inert | Very Good |
| Melting Temperature (°F) | 635 | 410 |
| CLTE (ASTM D695, x10^-5, in/in/°F) | 7.5 | 4 |