Short answer: in PTFE procurement, five property values actually drive decisions — density, tensile strength, elongation, dielectric strength and deformation under load (creep) — while most datasheet rows are resin-lot trivia for your application. Insist on values tested on finished parts, not resin brochures: the same resin can test 2x apart after bad sintering.
PTFE datasheets look alike because they copy resin-producer values. Two suppliers’ “identical” sheets can differ more than their datasheets suggest, because sintering quality — time, temperature, uniformity — changes the finished properties more than the resin choice does. Here is which numbers to ask for and how to read them.
The five values that matter
| Valeur | Healthy virgin range (finished part) | What off-range values indicate |
|---|---|---|
| Densité | 2.10–2.30 g/cm³ | Below 2.10: under-sintered or porous — permeation and strength suffer |
| Tensile strength | ~25–40 MPa (skived virgin) | Below ~20: reprocessed resin or poor sintering |
| Élongation | ≥200% (often 300–400%) | Low values: brittle, crystallinity problems |
| Dielectric strength | ≥10 kV/mm (thin wall) | Lower: voids or contamination — the density problem in electrical form |
| Deformation under load | per grade/filler | The creep number that predicts gasket and bearing life |
Reading values like a buyer, not a student
- Ask what was tested: “resin datasheet” values are the polymer-maker’s claim; demand finished-part test values with lot reference.
- Ask how it was tested: specimen geometry and temperature change results; consistent method is what makes supplier comparisons possible.
- Filled grades: require filler name/percentage plus the same five values on the composite — fillers change every row, and only tested rows mean anything.
- Trends over absolutes: a supplier’s values drifting down lot-over-lot is the early warning; one certificate proves nothing, three lots show a system.
Chunhuan tests finished products under ISO 9001 across its semi-finished and machined program (10,000+ grades, since 1985) and supplies values with lot references as standard. Send the five values as your spec; quotes that answer with tested lot data are quoting a product — the rest are quoting a datasheet.
Frequently Asked Questions
Which PTFE properties matter most in procurement?
Density, tensile strength, elongation, dielectric strength and deformation under load (creep) — tested on finished parts, with lot references.
Why do identical PTFE datasheets perform differently?
Sintering quality changes finished properties more than resin choice. Two ‘identical’ sheets can test 2x apart in tensile and density.
What does low tensile strength in PTFE indicate?
Usually reprocessed resin or poor sintering — genuine skived virgin PTFE tests ~25-40 MPa with elongation above 200%.
Should filled PTFE datasheets be compared the same way?
Yes, plus the filler name and percentage on the certificate — fillers change every property row and only tested composite values are meaningful.
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