Rau siab -siab qhov kev pab cuam ntawm 180 degree, qis -melt-flow- Performance index PFA resin (MFI 2) muaj kev nkag siab zoo dua thiab lub neej ntev dua li tus qauv MFI 8 resin, tab sis ntawm tus nqi ntawm kev ua haujlwm nyuaj dua thiab qis dua tshuaj lom neeg. Tsawg-MFI resin muaj qhov hnyav dua molecular (≈400 kDa vs. 200-250 kDa), uas ua rau cov neeg kho tshuab muaj zog thiab txo qis hauv qab siab. Rau 1.5 hli phab ntsa raj ntawm 180℃thiab 10 bar sab hauv siab, MFI 2 lub rhaub muaj sia nyob 10, 000+ teev ua ntej creep rupture, thaum MFI 8 lub rhaub dej tsis dhau 2,000-4,000 teev. Kev lag luam tawm -tawm: qis-MFI resin yuav tsum tau kub extrusion ntau dua (400–420℃vs{29}}–390 degree) thiab qeeb extrusion ceev, nce nqi tsim khoom los ntawm 20–40%. Rau chav ua haujlwm siab tshaj 160 degree, qis -MFI PFA yog qhov zoo dua. Rau qhov kub thiab txias (<140°C) or non-pressure applications, standard MFI 8 is adequate.
Creep Resistance Comparison ntawm 180 degree, 10 bar hoop stress (1.5 hli phab ntsa, 25 hli OD)
| PFA Qib | MFI (g/10 min) | Molecular Luj (kDa) | Sijhawm rau 1% Creep Strain (teev) | Lub Sijhawm Rau Repture (teev) | Hom Failure Hom |
|---|---|---|---|---|---|
| Ultra{0}} siab MW | 0.5–1 | 500+ | 5,000–8,000 | 15,000–25,000 | Cov pob txha tawg |
| Tsawg MW (kev ua haujlwm siab) | 2–3 | 350–450 | 3,000–5,000 | 8,000–15,000 | Creep rupture |
| Standard (lub hom phiaj dav dav) | 5–8 | 200–250 | 500–1,500 | 2,000–4,000 | Creep rupture |
| High flow (yooj yim extrusion) | 10–15 | 150–180 | 200–500 | 800–1,500 | nrawm nrawm |
| Recycled / reprocessed | 15+ | <150 | <200 | <500 | Kev ua tsis tiav tam sim ntawd |
Vim li cas qis -MFI Resin ua tau zoo dua ntawm qhov kub thiab txias
Ntawm 180 degree, PFA yog ze rau nws qhov muag muag (melting pib ntawm 305 degree, tab sis modulus poob qis dua 150 degree). High molecular hnyav chains muaj ntau entanglements, uas tiv thaiv saw slippage (creep). Cov saw luv luv (qhov hnyav molecular) swb dhau ib leeg yooj yim dua, ua rau nrawm nrawm thiab tawg. Kev sib raug zoo ntawm MFI thiab lub neej creep yog kwv yees li: Lub Neej ∝ 1 / (MFI)^1.5. MFI 2 resin muaj 8 × MFI ntawm MFI 2? Tos, piv MFI 8 rau MFI 2=4. Lub neej piv=4^1.5=8. Yog li MFI 2 yuav tsum kav 8 × ntev dua, uas phim cov ntaub ntawv (10,000 vs{19}},000 teev=5 × txawv, nyob rau hauv scatter).
Kev Sib Tw Ua Haujlwm rau Tsawg-MFI Resin
| Parameter | Standard MFI 8 | Tsawg MFI 2 | Kev cuam tshuam |
|---|---|---|---|
| Extrusion kub | 370-390 degree | 400-420 degree | Tus nqi zog siab dua |
| Extrusion ceev (m / min) | 5–10 | 2–4 | qeeb, qis dua |
| Tuag siab | Nruab nrab | 30-50% siab dua | Yuav tsum muaj cov cuab yeej muaj zog |
| Nto zoo | du | Tej zaum yuav rougher (melt fracture) | Tej zaum yuav xav tau polishing |
| Tus nqi (resin + ua) | Lub hauv paus | +20–40% | Tus nqi siab dua |
Piv txwv teb
A steam sterilizer (180°C, 8 bar) used 1.5 mm wall PFA heaters made from standard MFI 8 resin. Heaters failed after 1.5–2 years (≈3,500–5,000 hours). The plant switched to low-MFI resin (MFI 2.5) from the same manufacturer. Extrusion was slower (3 m/min vs. 7 m/min), and cost increased by 25%. The new heaters lasted 6+ years (>12,000 teev). Cov nroj tsuag suav tias tus nqi pib siab dua tau rov qab los hauv 2 xyoos los ntawm kev txo qis qis. Lawv tam sim no qhia MFI Tsawg dua lossis sib npaug li 3 rau txhua qhov kev pabcuam chav siab tshaj 150 degree.
Thaum Standard MFI 8 Tau Txais
Chav ntsuas kub tsawg dua lossis sib npaug li 150 degree: Creep tus nqi qis dua.
Tsawg siab (<3 bar): Hoop stress tsawg.
Kev pabcuam cuam tshuam (tsis txuas ntxiv): Cov polymer rov zoo thaum lub sijhawm tawm - mus.
Phab ntsa tuab (Ntau dua lossis sib npaug li 2.5 hli): Ntau cov ntaub ntawv nkag mus, tab sis tseem txwv los ntawm qhov hnyav molecular.
Chemical Resistance Trade-Tawm
Tsawg-MFI resin muaj crystallinity dua me ntsis (55–60% vs. 45-50% rau tus qauv), uas txo cov permeation tab sis kuj yuav txo qhov cuam tshuam. Qhov siab dua crystallinity yog qhov ua tau zoo rau cov tshuaj tiv thaiv (tsawg amorphous dawb ntim). Txawm li cas los xij, qhov tsis xws luag extrusion (melt fracture) tuaj yeem tsim cov pinholes yog tias tsis tswj tau. Rau cov tshuaj phem, qhov qis -MFI resin tsis qis dua; tej zaum nws yuav zoo dua vim muaj crystallinity ntau dua.
Xaus: Rau 180℃Chav, Tsawg-MFI (2–3) Extens Life 3–5 × Tshaj Standard MFI 8
Rau siab -siab qhov kev pab cuam ntawm 180 degree, lub PFA rhaub ua los ntawm qis-melt-flow-index resin (MFI 2–3) muab 3-5 × lub neej ntev dua li tus qauv MFI 8 resin vim siab dua molecular hnyav thiab superior creep resistance. Kev lag luam tawm - tawm yog nce nqi tsim khoom (20–40%) thiab kev tsim khoom qeeb. Rau qhov kev pab cuam txuas mus ntxiv rau saum 160 degree, tus nqi them nqi yog tsim nyog. Rau qhov ntsuas kub qis dua lossis tsis yog- cov ntawv thov siab, tus qauv MFI 8 txaus. Lub melt flow index yog qhov rais rau hauv qhov hnyav molecular, thiab qhov hnyav molecular txiav txim siab lub neej ntawm qhov kub siab. Tsawg MFI txhais tau tias lub neej ntev. High MFI txhais tau tias lub neej luv. Xaiv raws li. Hauv chav, mus qis. Koj lub rhaub yuav kav ntev. Cov nyiaj khaws cia hauv lub sijhawm poob yuav deb tshaj tus nqi them ua ntej. Qhov ntawd yog kev lag luam - tawm. Kev lag luam ntse.
