Tech Talk Blog

The first part of the answer is we need to know what kind of Teflon. DuPont’s family of Teflon products includes a number of different materials. PTFE is the best know of this family and the answer to your question for this material would be NO! PTFE does not hold up well at all in gamma radiation. As an example, 4Mrads of exposure reduces the tensile strength of the PTFE to 2% of it’s original value.

A better fluoropolymer for gamma irradiation would be DuPon’ts Tefzel product which is known by the chemical moniker of ETFE. In vacuum or air irradiation, Tefzel maintains a high level of physical integrity after long exposures.

Another fluoropolymer that does well in gamma is PCTFE, formerly known as Kel-F. PCTFE has minimal property loss even after doses of 16-18Mrads of exposure. Rates of property loss in all main categories are less than 30% which is quite good for fluoropolymers.

TriStar Plastics has more information on different methods of sterilization and how it affects most medical grade polymers. Ask The Experts – you’ll still like them when they’re angry (but they won’t be)!

Molecular weight and crystallinity are two factors in PTFE that determine many of it’s performance qualities. Both of these properties are highly dependant on the sintering operation of the PTFE production. If the material is cooked (sintered) too long or at too high a temperature it can degrade the polymer. Molecular weight is a measure of the polymer chain length and it affects flex life, tensile strength and elongation. As molecular weight increases so do these properties and paying attention to gel temperatures and dwell times during sintering is extra critical.

Crystallinity of PTFE can vary considerably depending on processing. This value can be seen in small variations in the specific gravity although in practice most PTFE materials fall in the 50-60 percent crystalline percentage. Increasing crystallinity decreases flex life, increases compressive stress and decreases recovery values, permeability and wear life. Other properties of PTFE, such as thermal, chemical, electrical and friction, are not generally affected by crystallinity changes.

So, sintering and other processing steps do a make a difference in deterimining the quality of PTFE. If you need to maximize the performance of your PTFE parts, including Rulon, Fluorosint, Ultraflon or even generic products, be sure you contact Tri Star Plastics first.  We can help you select the right material and the right process.