PTFE tsis nqus dej noo, tsis hlawv, thiab muaj huab cua tiv taus zoo

Suav lub npe ntawm PETF yog polytetrafluoroethylene, uas yog ib tug polymer ntawm tetrafluoroethylene. Cov lus Askiv luv yog PTFE. Lub hauv paus qauv ntawm PTFE yog. - CF2 - CF2 - CF2 - CF2 - CF2 - CF2 - CF2 - CF2 - CF 2 - CF2 -. Tsis muaj tshuaj lom rau tib neeg los ntawm nws tus kheej, tab sis ib qho ntawm cov khoom siv raw siv hauv cov txheej txheem tsim khoom, perfluorooctanoic acid ammonium (PFOA), yog xav tias yuav muaj peev xwm ua rau mob qog noj ntshav.

Tus txheeb ze molecular loj ntawm PTFE kuj loj, qhov qis yog ntau pua txhiab, qhov siab yog ntau tshaj 10 lab, feem ntau lab (cov degree ntawm polymerization yog nyob rau hauv qhov kev txiav txim ntawm 104, thaum lub polyethylene tsuas yog 103). Feem ntau, cov crystallinity yog 90-95 feem pua, thiab qhov kub ntawm melting yog 327-342 degree . CF2 units nyob rau hauv lub polytetrafluoroethylene molecule yog teem nyob rau hauv ib tug zigzag duab. Txij li lub vojvoog ntawm cov fluorine atom yog me ntsis loj dua li ntawm cov hydrogen, cov CF2 nyob ib sab tsis tuaj yeem ua tiav hauv trans, tab sis tsim ib txoj hlua helical twisted, uas yuav luag them los ntawm fluorine atoms. nto ntawm tag nrho cov saw hlau polymer. Cov qauv molecular no piav qhia ntau yam khoom ntawm PTFE. Thaum qhov kub qis dua 19 degree, lub 13/6 helix yog tsim; ntawm 19 degree, ib theem kev hloov pauv tshwm sim, thiab cov molecules yog me ntsis unwound los ua ib tug 15/7 helix.

Txawm hais tias qhov cleavage ntawm carbon-carbon bonds thiab carbon-fluorine bonds nyob rau hauv perfluorocarbons yuav tsum tau lub zog nqus ntawm 346.94 thiab 484.88 kJ / mol, ntsig txog, lub depolymerization ntawm PTFE rau 1 mol ntawm tetrafluoroethylene yuav tsum tsuas 171.38 kJ ntawm lub zog. Yog li ntawd, thaum kub kub tawg, PTFE feem ntau yog depolymerized rau hauv tetrafluoroethylene. Qhov hnyav poob (feem pua) ntawm PTFE ntawm 260, 370 thiab 420 degree yog 1 × 10-4, 4 × 10-3 thiab 9 × 10-2 ib teev, raws li. Nws tuaj yeem pom tias PTFE tuaj yeem siv tau ntev ntawm 260 degree. Txij li cov khoom muaj kuab lom heev xws li fluorophosgene thiab perfluoroisobutylene kuj tau tsim thaum lub sij hawm kub pyrolysis, tshwj xeeb yuav tsum tau them rau kev tiv thaiv kev nyab xeeb thiab tiv thaiv PTFE los ntawm kev sib cuag qhib nplaim taws.

Cov khoom siv kho tshuab Nws cov kev sib txhuam coefficient tsawg heev, tsuas yog 1/5 ntawm polyethylene, uas yog ib qho tseem ceeb ntawm perfluorocarbon nto. Thiab vim hais tias lub zog intermolecular ntawm cov fluorine-carbon saw muaj tsawg heev, PTFE tsis nplaum.

Polytetrafluoroethylene tswj cov khoom siv kho tshuab zoo heev hauv qhov kub thiab txias ntawm -196 txog 260 degree . Ib qho ntawm cov yam ntxwv ntawm perfluorocarbon polymers yog tias nws tsis ua nkig ntawm qhov kub thiab txias.

Tshuaj thiab Huab Cua Resistance PTFE zoo tiv thaiv txhua yam tshuaj tua kab mob tsuas yog cov hlau alkali molten. Piv txwv li, thaum boiled nyob rau hauv concentrated sulfuric acid, nitric acid, hydrochloric acid, los yog txawm nyob rau hauv aqua regia, nws qhov hnyav thiab zog tsis hloov, thiab nws yuav luag insoluble nyob rau hauv tag nrho cov kuab tshuaj, tsuas yog me ntsis soluble nyob rau hauv peralkanes (txog 0). .1g / 100g) siab tshaj 300 degree . PTFE tsis nqus dej noo, tsis yog-flammable, thiab ruaj khov heev rau oxygen thiab ultraviolet rays, yog li nws muaj huab cua zoo heev.

Cov khoom siv hluav taws xob PTFE muaj qhov tsis tshua muaj hluav taws xob tsis tu ncua thiab dielectric poob ntau zaus, thiab muaj qhov hluav taws xob tawg siab, ntim tiv taus thiab arc tsis kam.

Radiation resistance PTFE muaj cov hluav taws xob tsis zoo (104 rads), thiab nws yog degraded los ntawm high-zog hluav taws xob hluav taws xob, thiab hluav taws xob thiab txhua yam khoom ntawm cov polymer yog txo qis.