PTFE 25% Glass-Filled: Enhanced Wear Resistance & Dimensional Stability
Published: 2026-06-08
PTFE 25% glass-filled combines the universal chemical resistance of pure PTFE with significantly improved dimensional stability and wear resistance. The glass fiber filler reduces the cold-flow (creep) that limits unfilled PTFE in load-bearing...
PTFE 25% glass-filled combines the universal chemical resistance of pure PTFE with significantly improved dimensional stability and wear resistance. The glass fiber filler reduces the cold-flow (creep) that limits unfilled PTFE in load-bearing applications — compressive strength increases by approximately 40% compared to virgin PTFE. This grade is specified for: pump wear rings, lip seals in chemically aggressive environments, valve seats handling strong acids at moderate temperatures, and electrical insulators requiring both chemical inertness and mechanical stability. The trade-off: glass fibers make this grade mildly abrasive to mating surfaces — soft metal shafts running against 25GF PTFE bearings will experience accelerated wear unless hardened or coated.
Technical Properties
| Density | 2.22 g/cm³ |
|---|---|
| Tensile Strength | 25 MPa |
| Melting Point | 327 °C |
| Shrinkage Rate | 1.5-2.5% |
| Flexural Modulus | 1.8 GPa |
| Hdt | 120 °C at 1.82 MPa |
Engineering Tool: Shrinkage & Cost Estimator
Calculate part weight, mold cavity dimensions accounting for shrinkage, and material cost — all locally in your browser.
Equivalents & Cross-References
| Equivalent / Alternate | Action |
|---|---|
| Teflon 25GF | |
| Fluorosint 500 |
Frequently Asked Questions
When should I use glass-filled PTFE instead of virgin PTFE?
When the application involves compressive loads or requires dimensional stability. Virgin PTFE cold-flows (creeps) under sustained load — gaskets lose bolt tension over time, bearing clearances change. Glass-filled PTFE resists creep approximately 3-5× better than virgin PTFE. The downside is reduced chemical resistance (glass fibers can be attacked by hydrofluoric acid and strong alkalis) and abrasiveness to mating surfaces.
Is glass-filled PTFE FDA-compliant for food contact?
Some grades are — specifically those using FDA-compliant glass fiber sizing. Check the manufacturer's certification. Unfilled PTFE is universally FDA-compliant; filled grades require verification. For pharmaceutical and food processing, consider PTFE with FDA-compliant fillers or unfilled PTFE with modified processing to improve creep resistance.
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References & Industry Standards
- ASTM International. Standard Specifications for Engineering Plastics & Thermoplastics. astm.org
- UL Prospector. Plastics & Elastomers Material Database. ulprospector.com
- MatWeb. Material Property Data for Engineering Thermoplastics. matweb.com
- ISO 1043. Plastics — Symbols and Abbreviated Terms. iso.org