Densidad, mga uri at katangian ng PTFE
Natuklasan ang PTFE, na kilala sa trademark na Teflon, ng Kinetic Chemicals noong 1938. Aksidenteng natuklasan ni Roy Plunkett nang mag-polymerize ang tetrafluoroethylene gas sa pressurized cylinder at bumuo ng puting powder.
Mga katangian at gamit
Pangunahing bentahe ang dielectric property, kasama ang:
- mataas na densidad at dimensional stability;
- malawak na temperature range;
- ductility;
- strength;
- moisture resistance;
- mababang surface adhesion at self-cleaning;
- UV at ionizing-radiation resistance;
- wear at abrasion resistance;
- bioinertness;
- madaling machining.
Ginagamit sa bahay, food, automotive, medicine at industriya bilang:
- wire insulation, hose, pipe, vessel at fishing line;
- nonwoven noncombustible material, technical fabric at film;
- heat-resistant membrane, bearing at automotive part;
- pump/mixer part, valve at plumbing component;
- cable system at capacitor;
- high-pressure pipeline para sa chemically active medium.
Chemically stable at karaniwang ligtas sa approved condition, ngunit huwag lumampas sa working temperature. Mga kahinaan:
- mahal na equipment para sa forming at sintering;
- malakas na exhaust ventilation sa pagproseso;
- mapanganib ang polymer kapag lampas sa upper temperature limit.
Mga uri
Nag-iiba ang grade ayon sa chain at molecule. Nasa 1700–2240 kg/m³ ang densidad:
- F4 / PTFE — pinakasiksik, low-porosity, hydrophobic, hanggang +260 °C.
- F3 — mas mababa ang chemical at thermal resistance ngunit mas dense; melt-processable at may adhesion sa metal, ginagamit sa anticorrosion coating.
- F2 — abrasion-resistant, walang plasticizer, matibay, para sa aggressive medium, pipe at vessel.
- F40 — matibay, resistant sa boiling acid at ilang solvent, nonflammable at hindi nagpapadaan ng UV at radiation.
| Property | F2 | F3 | F4 | F40 | |
| Density (kg/m³) | 1780 | 2090–2160 | 2150–2240 | 1700 | |
| Failure stress, MPa | Tension | 44–45 | 35–43 | 16–35 | 27–50 |
| Compression | – | 55–60 | 10–12 | 50 | |
| Flexure | – | 60–80 | 14–18 | 34 | |
| Temperature, °C | Melting | 150–175 | 210–215 | 270–327 | 265–275 |
| Glass transition | –30…–20 | 50 | 127 | –90 | |
| Decomposition | 400 | 320 | 425 | 400 | |
| Operation | –45…+150 | –195…+190 | –260…+260 | –200…+200 | |
| Volume resistivity (Ω·m) | 10¹⁰–10¹³ | 10¹⁵–10¹⁷ | 10¹⁷–10¹⁸ | 10¹⁶ | |
Ginagawa bilang disc, plate, sheet, film, rod, granule at powder.
- 2.5 kg ang 1000×1000×1 mm sheet.
- Humigit-kumulang 0.18 kg ang 1000 mm long at 10 mm diameter rod.
Mga madalas itanong
Magkano ang bigat ng 1 m³ ng fluoropolymer?
Nasa humigit-kumulang 1700–2240 kg ayon sa grade. Para sa PTFE/F4, madalas 2150–2240 kg/m³.
Bakit mas mabigat ito kaysa maraming plastic?
Mataas ang densidad dahil sa chemical composition at polymer structure, kaya mas mabigat kaysa polyethylene at polypropylene.
Maaari bang painitin lampas sa working temperature?
Hindi. Maaaring mag-decompose at maglabas ng mapanganib na produkto, kaya sundin ang operating range ng grade.