PTFE Structure Property Ubale

Njira yomvetsetsa momwe fluorine imakhudzira ndikuwunika kusiyana pakati pa polyethylene (PE) ndi PTFE yomwe ndi fluoropolymer yomaliza potengera katundu ndi mawonekedwe.

Pali kusiyana kwakukulu pakati pa katundu wa PE ndi wa PTFE:

• * PTFE ndi amodzi mwa ma polima otsika kwambiri padziko lapansi
• *PTFE ndiye polima wosamva mankhwala
• *PTFE ndi imodzi mwama polima olimba kwambiri
• *Malo osungunuka ndi mphamvu yokoka ya PTFE ndizoposa kawiri za polyethylene

Kusiyana kwa PTFE ndi PE kumachitika chifukwa cha kusiyana kwa ma bond a CeF ndi CeH.Kusiyana kwamagetsi ndi makulidwe a F ndi H kumabweretsa zotsatirazi:

• *F ndiye mphamvu yamagetsi kwambiri pazinthu zonse (4 Paulings)
• *F ili ndi ma electron awiriawiri osagawana
• *F imasinthidwa mosavuta kukhala Fe
• *Mphamvu zama bond za CeF ndizokwera kuposa CeH
• *F ndi wamkulu kuposa H

Ma electronegativity a carbon pa 2.5 Paulings ndi apamwamba kuposa a haidrojeni komanso otsika kuposa electronegativity ya fluorine.Chifukwa chake, polarity ya chomangira cha CeF ndi chosiyana ndi chomangira cha CeH, ndipo chomangira cha CeF chimakhala chokhazikika kwambiri.Mu chomangira cha CeF, mathero a fluorine a bondi amakhala ndi mlandu woyipa poyerekeza ndi chomangira cha CeH chomwe mpweya wa kaboni umayikidwa molakwika.

Kusiyana kwa ma bond polarity a CeH ndi CeF kumakhudza kukhazikika kwapang'onopang'ono kwa maunyolo awiri a polima.Crystallization wa polyethylene kumachitika mu planar ndi trans conformation.PTFE akhoza kukakamizidwa kukhala conformation pa kwambiri kuthamanga kwambiri.PTFE, pansi pa 19 C, imawala ngati helix yokhala ndi 0.169 nm pa mtunda wobwereza: zimatengera ma atomu 13 C kuti kutembenuka kwa 180 kumalizike.Pamwamba pa 19 C, mtunda wobwereza ukuwonjezeka kufika pa 0.195 nm zomwe zikutanthauza kuti maatomu a kaboni 15 amafunikira pa kutembenuka kwa 180.Pamwamba pa 19 C maunyolo amatha kusuntha mwamakona, komwe kumakwera pamwamba pa 30 C mpaka kufika posungunuka (327 C).

Kulowetsedwa kwa F mmalo mwa H mu chomangira cha CeH kumakulitsa kwambiri mphamvu ya chomangira kuchoka pa 99.5 kcal/mole kwa chomangira cha CeH kufika pa 116 kcal/mole pachomangira cha CeF.Chifukwa chake, kukhazikika kwamafuta ndi kukana kwamankhwala kwa PTFE ndikokwera kuposa PE chifukwa mphamvu zambiri zimafunikira kuti muthyole chomangira cha CeF.Polarity ndi mphamvu ya chomangira cha CeF kumapangitsa kuti F atomu abstraction njira kuti nthambi zikhale zovuta.Mosiyana ndi izi, polyethylene yokhala ndi nthambi zambiri (> nthambi 8 pa ma atomu a kaboni 100) imatha kupangidwa.Njira yopangira nthambi ngati chida chosinthira crystallinity sizothandiza kwa PTFE.M'malo mwake ma comonomer okhala ndi magulu a pendenti ayenera kukhala ndi polymerized ndi TFE.

Crystallinity ya PTFE yosasungunuka ili m'kati mwa 92e98%, yogwirizana ndi unyolo wopanda nthambi.FEP, copolymer ya TFE ndi HFP, ili ndi crystallinity monga-polymerized ya 40e50%.Mu FEP, gulu la pendent CF3 limamangiriridwa ku carbon tertiary yomwe imakhala yosasunthika kwambiri kuposa maatomu a carbon ndi pulayimale.Mapiritsi owonongeka amasonyeza kutentha kwa 300 C kwa FEP (0.02% kuwonda) ndi 425 C kwa PTFE (0.03% kuwonda).