I-Polyethylene: iphuzu lokuqhakazila, izakhiwo zabathengi kanye nesicelo

Namuhla, isintu asikwazi ukwenza ngaphandle kwemishini yokufakelwa. Zinezimpawu eziningi eziyingqayizivele, zitholakalayo kanye nokukhiqizwa okungabizi kakhulu. Enye into enjalo i-polyethylene. I-melting point, kanye nezinye izici zobuchwepheshe, kufanele zicatshangelwe ngokucophelela. Phela, lokhu kungenye yezinsiza ezidumile kakhulu namuhla. Ingxenye engaphezu kwesigamu se-ethylene eyenziwa yimboni yamakhemikhali yomhlaba ithunyelwa ukukhiqiza i-polyethylene. Ukuze uqonde ukuthi kungani ethandwa kakhulu namuhla, kufanele ucabangele izici zalo.

Iyini into?

Ukwakhiwa kwe-molecule ye-polyethylene kuyinto elula. Ibukeka njengeketheni eliqukethe ama-athomu e-carbon. Kulowo nalowo ngamunye ama-molecule e-hydrogen amabili anamathiselwe. Ezweni kukhona ukuguqulwa kokubili kwalesi sici. Ahlukile ekwakheni. Lokhu kukhonjiswe ezintweni i-polyethylene enayo (iphuzu lokuqhakazila kanye nephuzu elibilisa, izakhiwo zabathengi). Imvelaphi yabo kuphela ebabumbene. Zombili lezi zinguquko zitholakala e-ethylene.

Uhlobo lokuqala lwe-polyethylene liqukethe ama-monomers ajwayelekile. I-degree yabo ye-polymerization ingu-5000 noma ngaphezulu. Ukuguqulwa kwesibili kunama-monomers we-branching. Ziqukethe ama-athomu e-carbon (kusuka ku-4 kuya ku-6).

Ukwakha i-polyethylene elayini, kusetshenziselwa izici ezikhethekile. Inqubo ye-polymerization iqala ekushiseni okufika ku-150 ° C.

Izimpawu

I-polymeri ye-thermoplastiki, ekhonjiswe ngophawu olusenyakatho, i-polyethylene ngathi. Iphuzu lokuqhakazila, izici zobuchwepheshe zendaba zenza zithandeke. I-crystallizes phakathi kwe--60 kuya ku-269 ° C.

Ikhwalithi yayo enhle kakhulu ukungabi khona kwe-polyethylene emanzi ngamanzi. Ekhaya, akuvezwanga ku-solvents ehlukahlukene. Awukwazi ukusabela ekamelweni lokushisa ngekasa elimnandi, izixazululo ezinamakhemikhali namakhemikhali.

Lapho izinga lokushisa likhuphuka lifika ku-60 ° C, le ndaba iba yingozi kwi-sulfuric ne-nitric acid. Ukusebenzisa ama-oxidants ukuphatha indawo ye-polyethylene, ukuchithwa koqweqwe lwendawo kufanele kulindeleke. Lezi zinto ziqala ukuncibilikiswa ngamanzi. Le mfanelo iyadingeka ukugcoba i-polyethylene.

Izindlela zokwenza i-polymerization

Kuye ngendlela yokwenza i-polymerization ye-ethylene, i-polyethylene inama-3 izinhlobo: okuphansi, ukucindezela okukhulu kanye nohlobo oluthile lwempahla. Lokhu kunquma ukuthi yiziphi izimfanelo ze-polyethylene ezizohlala nazo. Iphuzu lokuqhakazila, izakhiwo zobuchwepheshe zezinhlobo zonke zihlukile. Ngakho-ke, zisetshenziswe cishe kunoma iyiphi ingxenye yomsebenzi wesintu.

I-Polyethylene, ekhiqizwa ngaphansi kwengcindezi ephezulu, ilula. It polymerized by the method radical. Ukucindezela kulokhu kufinyelela ku-atm. 1-3. Ukushisa kungu-180 ° C. I-oksijeni kulokhu ibamba iqhaza njenge-initiator.

I-Polyethylene yokucindezela okuphansi kwenziwa ngosizo lwama catalysts e-Ziegler-Natta. Kule nqubo, i-solvent ephilayo ihlanganyela. Umshini wokusebenza awuwona ngaphansi kuka-5 atm., Futhi izinga lokushisa lidlula u-80 ° С.

I-polyethylene ephakathi nendawo (ephakathi) iphakathi phakathi kwezinhlobonhlobo ezicutshangwayo. Lokhu kuphathelene nezimfanelo zayo nezakhiwo. Yenziwa ngecindezela lika-30-40 atm. Uma usebenzisa i-metallocene catalysts, kungenzeka ukuthola umkhiqizo wamandla akhulisiwe.

Isizathu sokungafani kwezakhiwo ze-polyethylene

Ukwakhiwa kwamagatsha ama-macromolecules kunquma izinto eziqukethe i-polyethylene. Iphuzu lokuqhaqhazela nobukhulu kuxhomeke kuhlobo lwezinketho. Uma kunezinto ezinamandla kakhulu, impahla enwebekayo enezakhi ezincane zekristallini itholakala kulesi sakhiwo.

Lesi sici sakhiwo senza kube nzima kakhulu ukwakha iphakethe elikhudlwana lama-macromolecules, okuba yisithiyo kwizinga le-crystallinity elingu-100%. Le ndaba nayo inesigaba sezulu. Iqukethe izingxenye ezingenakulinganiswa zezigaba ze-molecule. Indlela yokukhiqiza inquma inani lama-cristalline nezigaba zomkhathi. Lesi sici esithinta izindawo ze-polyethylene.

Ngakho-ke, amafilimu akhiqizwa ngaphansi kwengcindezi ephansi ayigugu kakhulu kunezinye izinhlobo zazo. Ukwakhiwa kwe-crystallinity (isisindo samangqamuzana), ukuphakama kokusebenza komshini. Ngakho-ke, ngesimo sefilimu, izinto ezibonakalayo zivulekile futhi zisezingeni eliphezulu. Kodwa amashidi e-polyethylene ayoba nzima futhi opaque.

Umphumela wokushisa

Ngaphansi kwethonya lemvelo, izimfanelo okushiwo ushintsho lwe-polyethylene. Iphuzu lokuqhafaza kwalesi sici futhi sincike emvelweni wokukhiqiza. Ngendlela evamile, lapho ukushisa i-polyethylene kudlula izigaba eziningana. Ekuqaleni kuba lula, kunwebeka okukhulu. Ilula ngokulula ngaphansi kwethonya lamathonya anomshini.

Ukushisa okubhakabhaka lapho i-polyethylene ejwayelekile elahlekelwa khona izici zayo ziyi-70 ° C. Ngokunyuka kwalo okuqhubekayo, lezinto ziyancipha ngisho nakakhulu. Ilahlekelwa ngokuphelele isimo esivamile uma ishisa ngo-120 ° C. Esikhathini somthamo wamanzi, kuguqulwa ekushiseni kuka-130 ° C.

Ngaphezu kokushisa okushisayo, kubalulekile ukucabangela umphumela wemisebe ye-ultraviolet. Uma le nto isetshenziselwa imikhiqizo yomgwaqo, kubalulekile ukukhetha izinhlobo ezinamandla. Uma kungenjalo, i-polyethylene elula, elashelele emva konyaka wokusebenza ngaphansi kwelanga eliqondile kuyoba nzima futhi inzima. Ngisho nombala wezinto eziguqukayo ngesikhatsi.

I-Polyethylene yokucindezela okuphansi

Uhlobo ngalunye lwezinto ezinezimfanelo ezikhethekile. Lokhu kwandisa ububanzi bezinhlelo zokusebenza i-polyethylene enayo. Iphuzu lokuqhakazila (ukuphakama okukhulu) liyi-120-135 ° C. Kwezimpahla ngabanye, ukumelana nokushisa kungu-110 ° C. Ukuphakama kwama-molecular high kunomthelela ekwandeni ukumelana nokushisa komthelela.

Ngaphandle kwalezi zimfanelo, i-polyethylene ephansi yokucindezela ayitholakali kakhulu ekuhlaselweni kwamakhemikhali. Kodwa-ke, ukuqina ngokweqile kwama-molecule emazingeni aphansi asezingeni eliphansi kwenza ukuthi le nto ibhekeke, ibuye ibe yinto egcwele imithombo yamagesi, amagesi.

Loluhlobo lwempahla lunemibono emihle ye-dielectric. Kuyinto engasebenzi, kodwa kulula ukukhiqizwa ezimbonini.

I-Polyethylene yokucindezela okukhulu

Leli qembu liqukethe i-polyethylene elula, elula. I-melting point, izakhiwo ze-crystallization azivumeli ukwenza izinto eziphakeme, amandla okushisa okuvela kulo. Kuye ngokuthi umkhiqizo ungaba nobani obuhlukile. Iphuzu labo lokuqhakazila livela ku-60 kuya ku-90 ° C.

Njengolunye uhlobo lwangaphambilini lwezinto ezibonakalayo, i-polyethylene ephezulu kakhulu ihlala isikhathi eside uma isisindo samangqamuzana sanda. Iba yinto engaphansi kakhulu yamakhemikhali, amathonya e-ultraviolet. Kodwa lokhu kunciphisa ikhono layo lokumelana nokushaqeka. Ku-polyethylene enjalo ekuqhekekeni okukhulu kwama-frosts avela, ama-breaks. Iba yinto enomphelela emiphakeni kanye negesi.

Izinto ezinjalo nazo zinempahla emihle ye-dielectric. Akabonisi ukumelana namafutha, amafutha. Kodwa le nto ingakwazi ukuqukatha imisebe yemisebe. Ngokwemvelo, le ndaba nayo inert, kodwa kulula ukuyisebenzisa.

Ukusetshenziswa kwe-polyethylene yokucindezela okuphansi

Ikhwalithi ehambelana nalokhu kunquma ukuthi insimu yesicelo iphi i-polyethylene. Iphuzu lokuqhakaziza (ukusetshenziswa kwalesi sibonakaliso kuyimpoqo ekukhetheni umkhiqizo ngamunye) kwenza kube lula ukwenza amaphakheji nokupakisha kusuka kulolu hlobo. Ngokuvamile, isitsha sikhiqizwa ukushaya. Lezi zingaqukatha izimonyo noma amakha, iziqukathi zokudla.

I-canisters neziqukathi ze-polyethylene ephansi kakhulu zisetshenziselwa izimboni zezimoto nezamakhemikhali, ekwakheni imiphongolo kanye namathangi okushisa.

Ukukhiqizwa kwamafilimu okupakisha okuvela kwento efanayo kufinyelela phambili. Isetshenziswa kakhulu ekukhiqizeni amapayipi, ukufakwa. Kuyinto impahla eshibhile futhi eqinile. Iyakwazi ukususa ezinye imikhiqizo yokuncintisana emakethe.

Ukusetshenziswa kwe-polyethylene ephakeme kakhulu

I-Polyethylene, iphuzu lokuqhakazila elingaphansi kweyenguqulo yangaphambilini, lisetshenziselwa ukukhiqizwa kwamafilimu ezolimo, imboni yokudla nezinye izinhloso zobuchwepheshe. Ukufuna kwalo kukhula njalo.

Amafilimu ahlukene ngenhloso yezolimo angakwazi ukuqinisa ngokwengeziwe, umbala wabo uphinde uhlukile. Zisetshenziswa ezindlini zokugcina izithombo, emasimini ukuthuthukisa izinga nevolumu yesitshalo.

Amafilimu okudla, amaphakethe emhlabeni wonke adliwa minyaka yonke ngezinga elikhulu. Loluhlobo lwempahla luye lwasuka emikhiqizweni emikhulu yamakethe amakhulu kusuka kwezinye izinto.

Isakhiwo sokusetshenziswa

I-Polyethylene, iphuzu lokuqhakazila elibeka insimu yesicelo sayo, liyadingeka kakhulu emhlabeni wonke. Isakhiwo sokusetshenziswa kwalesi sihloko sithandeka kakhulu. I-60-70% ye-polyethylene isetshenziselwa ukwenza amashidi namafilimu.

Okunye okuyingxenye enkulu yenani eliphelele lokukhiqizwa lihlala ngemikhiqizo etholakalayo ngomjovo wokufakelwa noma nge-extrusion. Ukukhiqizwa okungeyona okungadingekile kokufakelwa kwezingcingo zikagesi, amapayipi nokufakwa. Futhi, i-polyethylene isetshenziselwa ukukhiqiza imikhiqizo ngokushaya nokunye okunjalo.

Ekukhiqizeni amashidi namafilimu, i-polyethylene ephakeme kakhulu (isibalo esiphansi) cishe isetshenziswa ngaso sonke isikhathi. Zenziwe ngezindlela ezahlukene. Ubukhulu befilimu bububanzi buka 0.03-0.3 mm, kanye namashidi - 1-6 mm.

Ngaphezu kokufaka amaphakheji, lolo lwazi lungenza izikhwama, izikhwama, ama-liners amabhokisi, amabhokisi nezinye iziqukathi. Izakhiwo umkhiqizo okufanele uzuze zinqunywa ngendlela i-polyethylene ekhiqizwa ngayo. Ekupheleni kokukhiqizwa, uhlobo ngalunye lwempahla lunikezwa umkhiqizo. Kuyasiza ukukhetha uhlobo olufanele lwempahla kunoma iyiphi imboni.