PTFE vs Other Engineering Plastics: How to Choose the Right Sealing Material

Designers specifying sealing materials often have a shortlist of three to six polymers on the drawing. PTFE is one of them, but it is rarely the cheapest option in raw-material cost. The right comparison has to balance material cost against functional requirements and service life. This article works through a practical comparison of PTFE against the other common engineering plastics — PVC, PP, PE, nylon, Delrin (POM), UHMW-PE, and PEEK — and ends with a four-step selection workflow that we use with our customers.

Why Compare PTFE to Other Materials?

The wrong substitution costs more than the savings: a seal that fails in weeks erases months of planning. The right comparison has to balance cost against five variables:

• Chemical resistance to the actual process fluid (not just the generic class — concentration, temperature, and impurities all matter).
• Continuous service temperature, the upper limit at which the material still holds at least 50% of its room-temperature properties.
• Mechanical behaviour under load (creep, friction, wear rate).
• Regulatory acceptance (FDA, USP, EU 1935/2004, NSF, KTW, WRAS) where applicable.
• Manufacturability — how cleanly it cuts, moulds, extrudes, welds, or bonds.

A wrong substitution can fail in weeks. The right substitution can save 30-80% on material cost without changing service life.

Material Performance Comparison

PTFE vs Specific Materials

PTFE vs PEEK

PEEK handles higher pressure and tighter tolerance, and resists radiation better, but costs 8-10× per kg. Choose PTFE for chemical, food, and laboratory applications; choose PEEK for aerospace, semiconductor, and high-pressure hydraulic service where the 250 °C continuous rating and 100+ MPa tensile strength are needed.

PTFE vs Delrin (POM)

Delrin is cheaper and machines very cleanly, with tight as-machined tolerance. It cannot, however, match PTFE in chemicals and is limited to around 100 °C continuous. Delrin is the right choice for dry mechanical parts; PTFE is the right choice for wet chemical service.

PTFE vs UHMW-PE

UHMW is tougher and more abrasion-resistant at low temperature, but cannot be compression-moulded into rods thicker than about 50 mm, and has a lower continuous service temperature. UHMW wins for chute liners and bulk-material handling; PTFE wins for precision seals and chemical service.

PTFE vs PVC

PVC is much cheaper and easier to weld, but has a limited temperature range and much poorer chemical resistance across the solvent spectrum. PVC is the right choice for water and drainage plumbing; PTFE is the right choice for chemical, food, and high-purity applications.

PTFE vs PP (polypropylene)

PP is the lowest cost, lightest, and easiest to weld, but has the lowest temperature and chemical resistance. PP is suitable for dilute aqueous service; PTFE for concentrated, hot, or organic media.

Selection Workflow

A four-step process used by our team when a customer asks "which polymer":

1. List the process media (chemical or mixture), concentration, and peak temperature.
2. List the pressure or load and any motion (static, rotary, reciprocating).
3. List the regulatory needs (FDA, USP, EU).
4. Filter the table above to the surviving materials; pick the cheapest that meets the requirements.

When PTFE is Not the Best Choice

There are a handful of cases where PTFE is the wrong starting point. In each, the wrong material is usually obvious from the application brief:

• High-load dry bearing surfaces: PEEK, UHMW, or filled Delrin handle sustained load and dynamic motion with lower wear rate and creep than PTFE.
• Structural parts at high temperature: PEEK and PI (polyimide) hold mechanical properties above 200 °C more reliably than PTFE.
• Weldable, low-cost aqueous pipework: PVC or PP is lower cost and supports solvent cement or hot-plate welding.
• Abrasion-resistant chute liners: UHMW is the workhorse; PTFE handles abrasion less well than HDPE or UHMW.
• Tight-tolerance structural parts: PEEK and Delrin hold tolerance under load and temperature where PTFE will creep.

Cost vs Total Life

Reading the TDS

When comparing technical data sheets, three numbers matter most for sealing applications:

1. Continuous service temperature (the upper number where 50% of room-temperature properties still hold after long-term ageing).
2. Tensile strength and elongation (govern load-bearing capacity and ductility during installation).
3. Chemical compatibility charts from the supplier or from ASTM D543 testing.

Ignore the tensile strength of virgin PTFE at room temperature (around 20-30 MPa) when sizing a load-bearing part — the operating temperature is the dominating variable.

A 100 mm PTFE gasket sheet costs more than the equivalent PVC plate and is similar in price to a UHMW plate. Over a 10-year life in chemical service, the PTFE sheet is replaced once (or never), while the PVC plate is replaced several times. The PTFE choice ends up cheaper per year even with the higher initial purchase, before counting the cost of any downtime.

Frequently Asked Questions

Summary and Related Reading

PTFE is the most chemically inert, highest temperature, and most FDA-accepted engineering plastic available at moderate material cost. It is the right starting point for any sealing or containment problem involving corrosive media, food, or pharmaceuticals. Where PTFE is over-specified for a particular application, the right replacement usually comes from PEEK (higher load), Delrin (dry mechanical), UHMW (abrasion), or PVC / PP (low-cost aqueous service). For a deeper dive on chemical compatibility, see our PTFE chemical resistance guide; for the material physics and properties, see the PTFE properties page.

LIANTUO PTFE supplies rod, sheet, tape, and CNC-machined components in PTFE and complementary engineering plastics for industrial buyers worldwide. Send a drawing or application brief to sales@liantuoptfe.com for a practical engineering quote.