PTFE Ulwakhiwo lwePropati yoBudlelwane

Indlela yokuqonda impembelelo ye-fluorine kukuhlola umahluko phakathi kwe-polyethylene (PE) kunye ne-PTFE eyona nto iphambili ye-fluoropolymer ngokweempawu kunye neempawu.

Kukho umahluko obalulekileyo phakathi kweepropati ze-PE kunye naleyo ye-PTFE:

• • I-PTFE yenye yeepholima zamandla ezisezantsi
• *I-PTFE yeyona polima ixhathisayo kwikhemikhali
• *I-PTFE yenye yeepholima ezizinzile ngokushushu
• *Indawo yokunyibilika kunye nobunzima obuthile be-PTFE bungaphezulu kokuphindwe kabini kwezo ze-polyethylene

I-PTFE kunye ne-PE iyantlukwano ibalelwa kumahluko we-CeF kunye ne-CeH bond.Umahluko kwiipropati ze-elektroniki kunye nobukhulu be-F kunye no-H bukhokelela kolu qwalaselo lulandelayo:

• *F ngowona mbane unamandla kuzo zonke iziqalelo (4 Paulings)
• *F inee-electron pairs ezingabiwanga
• *F iguqulelwa ngokulula ngakumbi kuFe
• *Amandla ebhondi ye-CeF aphezulu kune-CeH
• *F inkulu kunoH

I-electronegativity yekhabhoni kwi-2.5 Paulings iphakamile noko kune-hydrogen kwaye ingaphantsi kune-electronegativity ye-fluorine.Ngenxa yoko, ipolarity ye-CeF bond ichasene naleyo yebhondi ye-CeH, kwaye ibhondi ye-CeF yahlulwa kakhulu.Kwibhondi ye-CeF, isiphelo sefluorine sebhondi sihlawuliswa kakubi xa kuthelekiswa nebhondi ye-CeH apho ikhabhoni ihlawuliswa kakubi.

Umahluko kwi-bond polarity ye-CeH kunye ne-CeF ichaphazela uzinzo olunxulumeneyo lwemixokelelwane yamakhonkco amabini epholima.I-Crystallization ye-polyethylene yenzeke kwiplani kunye ne-trans conformation.I-PTFE inokunyanzelwa ukuba ibe yingqungquthela kuxinzelelo oluphezulu kakhulu.I-PTFE, engaphantsi kwe-19 C, ikhazimla njenge-helix ene-0.169 nm ngomgama ophinda-phindayo: kuthatha i-athomu ze-13 C kwi-180 ukujika ukuba igqitywe.Ngaphezulu kwe-19 C, umgama ophindayo uyanyuka ukuya kwi-0.195 nm okuthetha ukuba ii-athomu ze-carbon ezili-15 ziyafuneka kwi-180 turn.Ngaphezulu kwe-19 C amatyathanga ayakwazi ukufuduka kwe-angular, okunyuka ngaphezu kwe-30 C de kufike kwindawo yokunyibilika (327 C).

Ukutshintshwa kwe-F kwi-H kwibhondi ye-CeH kwandisa kakhulu amandla ebhondi ukusuka kwi-99.5 kcal/mole yebhondi ye-CeH ukuya kwi-116 kcal/mole yebhondi ye-CeF.Ngenxa yoko, ukuzinza kwe-thermal kunye nokumelana neekhemikhali ze-PTFE kuphezulu kune-PE kuba amandla amaninzi afunekayo ukuphula ibhondi ye-CeF.I-polarity kunye namandla ebhondi ye-CeF inika indlela yokutsalwa kwe-athomu ye-F ukuze kube nzima ukwenza i-branching.Ngokwahlukileyo, i-polyethylene ene-branched kakhulu (> amasebe ayi-8 kwii-athom zekhabhoni ezili-100) inokwenziwa.Indlela yesebe njengesixhobo sokunyenyisa ikristale ayisebenzi kwi-PTFE.Endaweni yoko ii-comonomers ezinamaqela e-pendent kufuneka zenziwe i-polymerized nge-TFE.

I-Crystallinity ye-PTFE engazange inyibilike ikuluhlu lwe-92e98%, ehambelanayo nesakhiwo sekhonkco esingenamasebe.I-FEP, i-copolymer ye-TFE kunye ne-HFP, ine-crystallinity njenge-polymerized ye-40e50%.Kwi-FEP, iqela le-CF3 elilengayo libotshelelwa kwikhabhoni ephezulu engazinzanga kangako ngokwe-thermal kunee-athom zekhabhoni eziziiprayimari nezesekondari.Iingqungquthela zokuthotywa zibonisa ukuthotywa kweqondo lokushisa kwe-300 C ye-FEP (0.02% ukulahleka kwesisindo) kunye ne-425 C ye-PTFE (0.03% ukulahleka kwesisindo).