Igama Lomkhiqizo:i-polyurethane

Isakhiwo samangqamuzana omkhiqizo:

Izakhiwo Zekhemikhali:

I-polyurethanes yaqala ukukhiqizwa futhi yaphenywa nguDkt. Otto Bayer ngo-1937. I-polyurethane iyi-polymer lapho iyunithi ephindaphindayo iqukethe i-urethane moiety.Ama-urethane aphuma kuma-carbamic acid akhona kuphela ngendlela yama-esters awo[15].Inzuzo enkulu ye-PU ukuthi uchungechunge alukhiwanga kuphela ama-athomu ekhabhoni kodwa kunalokho ama-heteroatom, umoya-mpilo, ikhabhoni ne-nitrogen[4].Ngezicelo zezimboni, inhlanganisela ye-polyhydroxyl ingasetshenziswa.Ngokufanayo, izinhlanganisela ze-nitrogen ezisebenza nge-poly-functional zingasetshenziswa ekuxhumaneni kwe-amide.Ngokushintsha nokushintshanisa i-polyhydroxyl ne-polyfunctional nitrogen compounds, ama-PU ahlukene angahlanganiswa[15].Ama-polyester noma ama-polyether resins aqukethe amaqembu e-hydroxyl asetshenziselwa ukukhiqiza i-polyesteror polyether-PU, ngokulandelana[6].Ukwehluka kwenani lokushintshwa kanye nesikhala phakathi nangaphakathi kwamaketango egatsha kukhiqiza ama-PU asuka kolayini ukuya kwengamagatsha futhi angu-9 avumelanayo kuya kokuqinile.I-Linear PUs isetshenziselwa ukwenza imicu nokubumba[6].Ama-PU aguquguqukayo asetshenziswa ekukhiqizeni ama-ejenti abophayo kanye nama-coatings[5].Amapulasitiki anegwebu aguquguqukayo futhi aqinile, akha iningi lama-PU akhiqizwayo, angatholakala ngezindlela ezahlukahlukene embonini[7].Kusetshenziswa ama-prepolymers aphansi we-molecular mass, kungakhiqizwa ama-block copolymers ahlukahlukene.Iqembu letheminali le-hydroxyl livumela amabhlogo ashintshanayo, abizwa ngokuthi amasegimenti, ukuthi afakwe ochungechungeni lwe-PU.Ukwehluka kulawa masegimenti kuholela kumazinga ahlukahlukene wamandla aqinile nokunwebeka.Amabhulokhi ahlinzeka ngesigaba sekristalu esiqinile futhi aqukethe i-chain extender abizwa ngokuthi amasegimenti aqinile[7].Lezo ezikhiqiza isigaba se-amorphous rubbery futhi equkethe i-polyester/polyether ibizwa ngokuthi amasegimenti athambile.Ngokwezentengiselwano, lawa ma-polymer block aziwa njenge-Segmented Pus

Isicelo:

I-polyurethanes ingenye yezinto eziguquguqukayo kakhulu emhlabeni namuhla.Ukusetshenziswa kwabo okuningi kusuka kugwebu oluguquguqukayo kufenisha ewupholstered, kuya kugwebu oluqinile njengokufakwa ezindongeni, ophahleni nasezintweni zikagesi ku-thermoplastic polyurethane esetshenziswa emishinini yezokwelapha nasezicathulweni, kuya ezingubo, okokunamathiswa, ama-sealant nama-elastomer asetshenziswa phansi nasezindaweni zangaphakathi zezimoto[17,18] ].Ama-polyurethanes aye asetshenziswa kakhulu phakathi neminyaka engamashumi amathathu edlule ezinhlobonhlobo zezicelo ngenxa yokunethezeka kwawo, izinzuzo zezindleko, ukonga amandla kanye nokuzwakala kwemvelo okungaba khona.Yiziphi ezinye zezinto ezenza i-polyurethanes ithandeke kangaka?Ukuqina kwe-polyurethane kunomthelela omkhulu empilweni ende yemikhiqizo eminingi.Izandiso zomjikelezo wokuphila komkhiqizo nokongiwa kwensiza kuwukucatshangelwa okubalulekile kwemvelo okuvame ukukhetha ukukhethwa kwama-polyurethanes[19-21].Ama-Polyurethanes (PUs) amele isigaba esibalulekile sama-polymers we-thermoplastic kanye ne-thermoset njengoba izakhiwo zawo zemishini, ezishisayo, namakhemikhali zingavunyelaniswa ukusabela kwama-polyols ahlukahlukene nama-poly-isocyanate.