Ukutholwa kwe-polyurethane [PU] kuhlehlela emuva onyakeni we-1937 ngu-Otto Bayer kanye nozakwabo emalabhorethri akwa-IG Farben eLeverkusen, eJalimane.Imisebenzi yokuqala igxile emikhiqizweni ye-PU etholwe ku-aliphatic diisocyanate kanye ne-diamine eyenza i-polyurea, kuze kube yilapho izici ezithokozisayo ze-PU ezitholwe ku-aliphatic diisocyanate ne-glycol, zatholakala.I-Polyisocyanates yaqala ukutholakala ngezohwebo ngonyaka we-1952, ngemuva nje kokukhiqizwa kwesikali se-PU kwafakazelwa (ngemuva kweMpi Yezwe II) kusuka ku-toluene diisocyanate (TDI) kanye ne-polyester polyols.Eminyakeni eyalandela (1952-1954), izinhlelo ezahlukene ze-polyester-polyisocyanate zathuthukiswa yi-Bayer.
Ama-polyester polyols kancane kancane athathelwa indawo ama-polyether polyols ngenxa yezinzuzo zawo ezimbalwa njengezindleko eziphansi, ukuphatha kalula, kanye nokuzinza kwe-hydrolytic okuthuthukisiwe kunangaphambili.I-Poly(tetramethylene ether) glycol (PTMG), yethulwa yi-DuPont ngo-1956 nge-polymerizing tetrahydrofuran, njenge-polyether polyol yokuqala etholakala kwezohwebo.Kamuva, ngo-1957, i-BASF ne-Dow Chemical bakhiqiza ama-polyalkylene glycols.Ngokusekelwe ku-PTMG kanye ne-4,4'-diphenylmethane diisocyanate (MDI), kanye ne-ethylene diamine, i-Spandex fiber ebizwa ngokuthi i-Lycra yakhiqizwa i-Dupont.Emashumini eminyaka, i-PU yathweswa iziqu kumagwebu e-PU aguquguqukayo (1960) yaya kumagwebu e-PU aqinile (i-polyisocyanurate foams-1967) njengama-agent afutha amaningana, ama-polyether polyols, ne-polymeric isocyanate njenge-poly methylene diphenyl diisocyanate (PMDI) yatholakala.Lawa magwebu e-PU asekelwe ku-PMDI abonise ukumelana okuhle kokushisa kanye nokubambezeleka komlilo.
Ngo-1969, kwasungulwa ubuchwepheshe be-PU Reaction Injection Molding [PU RIM] obuqhubekela phambili ku-Reinforced Reaction Injection Molding [RRIM] bukhiqiza izinto ezisebenza kahle ze-PU okwathi ngo-1983 zakhiqiza imoto yokuqala yepulasitiki e-United States.Ngo-1990s, ngenxa yokuqwashisa okukhulayo mayelana nezingozi zokusebenzisa i-chloro-alkanes njengama-ejenti afuthayo (i-Montreal protocol, 1987), amanye ama-agent afuthayo atheleka emakethe (isb, i-carbon dioxide, i-pentane, 1,1,1,2- tetrafluoroethane, 1,1,1,3,3- pentafluoropropane).Ngasikhathi sinye, ubuchwepheshe bokugcotshwa kwe-PU enamaphakethe amabili, i-PU-polyurea bungene ekudlalweni kwangaphambili, okube nezinzuzo ezibalulekile zokungazweli umswakama ngokusebenza kabusha okusheshayo.Kwabe sekuqhakaza isu lokusebenzisa uwoyela wemifino asuselwa ku-polyols ukuthuthukisa i-PU.Namuhla, umhlaba we-PU usuqhamuke kude kuma-PU hybrids, izinhlanganisela ze-PU, i-PU engeyona isocyanate, nezinhlelo zokusebenza eziguquguqukayo emikhakheni eminingi eyahlukene.Izithakazelo ku-PU zaphakama ngenxa yokuhlanganisa kwazo okulula nephrothokholi yohlelo lokusebenza, ama-reactants alula (ambalwa) ayisisekelo kanye nezakhiwo eziphakeme zomkhiqizo wokugcina.Izigaba eziqhubekayo zinikeza incazelo emfushane yezinto ezingavuthiwe ezidingekayo ku-PU synthesis kanye nekhemistri evamile ehilelekile ekukhiqizeni i-PU.
Isimemezelo:Isihloko sicashuniwe © 2012 Sharmin kanye no-Zafar, umnikazi welayisensi u-InTech.Ukuxhumana nokufunda kuphela, ungenzi ezinye izinjongo zezohwebo, akumele imibono nemibono yenkampani, uma udinga ukuphrinta kabusha, sicela uxhumane nomlobi wokuqala, uma kukhona ukwephulwa, sicela usithinte ngokushesha ukuze wenze ukucubungula ukususa.