Ukufunyanwa kwe-polyurethane [PU] kubuyela emva kunyaka we-1937 ngu-Otto Bayer kunye noogxa bakhe kwiilabhoratri ze-IG Farben eLeverkusen, eJamani.Imisebenzi yokuqala igxile kwiimveliso ze-PU ezifunyenwe kwi-aliphatic diisocyanate kunye ne-diamine eyenza i-polyurea, de iipropati ezinomdla ze-PU ezifunyenwe kwi-aliphatic diisocyanate kunye ne-glycol, zafunyanwa.I-Polyisocyanates yafumaneka ngorhwebo ngonyaka ka-1952, kwakamsinya nje emva kokuba imveliso yesikali sorhwebo yePU yabonwa (emva kweMfazwe Yehlabathi II) ukusuka kwi-toluene diisocyanate (TDI) kunye neepolyester polyols.Kwiminyaka eyalandelayo (1952-1954), iinkqubo ezahlukeneyo zepolyester-polyisocyanate zaveliswa yiBayer.
Iipolyester polyols ngokuthe ngcembe zatshintshwa ziipolyether polyols ngenxa yeenzuzo zazo ezininzi ezinje ngexabiso eliphantsi, ukuphathwa ngokulula, kunye nokuphuculwa kozinzo lwe-hydrolytic kuneyangaphambili.I-Poly(tetramethylene ether) glycol (PTMG), yaziswa yi-DuPont ngo-1956 nge-polymerizing tetrahydrofuran, njenge-polyether polyol yokuqala efumanekayo kurhwebo.Kamva, kwi-1957, i-BASF kunye ne-Dow Chemical yavelisa i-polyalkylene glycols.Ngokusekelwe kwi-PTMG kunye ne-4,4'-diphenylmethane diisocyanate (MDI), kunye ne-ethylene diamine, i-Spandex fiber ebizwa ngokuba yi-Lycra yaveliswa yi-Dupont.Kumashumi eminyaka, i-PU yaphumelela kwi-PU foams (1960) ukuya kumagwebu e-PU eqinile (i-polyisocyanurate foams-1967) njengee-agent ezininzi zokuvuthela, i-polyether polyols, kunye ne-polymeric isocyanate njenge-poly methylene diphenyl diisocyanate (PMDI) yafumaneka.Ezi foams ze-PU ezisekelwe kwi-PMDI zibonise ukuxhathisa okulungileyo kwe-thermal kunye ne-flame retardance.
Ngo-1969, itekhnoloji ye-PU Reaction Injection Molding [PU RIM] yaziswa eyaqhubela phambili kwi-Reinforced Reaction Injection Molding [RRIM] ivelisa imathiriyeli yokusebenza ephezulu ye-PU eyathi ngo-1983 yavelisa imoto yokuqala yomzimba weplastiki eMelika.Ngoo-1990s, ngenxa yokunyuka kolwazi malunga neengozi zokusebenzisa i-chloro-alkanes njengee-arhente zokuvuthela (i-Montreal protocol, 1987), ezinye ii-arhente zokuvuthela eziye zagalelwa kwimarike (umz., icarbon dioxide, pentane, 1,1,1,2- tetrafluoroethane, 1,1,1,3,3- pentafluoropropane).Kwangelo xesha, iipakethi ezimbini ze-PU, i-PU-polyurea yetekhnoloji yokutshiza yeza kumdlalo wangaphambili, oye wathwala izibonelelo ezibalulekileyo zokungakhathali ngokufuma nokuphinda usebenze ngokukhawuleza.Emva koko kwaqhakaza iqhinga lokusetyenziswa kweoyile yemifuno esekwe kwi-polyols kuphuhliso lwePU.Namhlanje, ihlabathi le-PU livela kumgama omde ukusuka kwi-PU hybrids, i-PU composites, i-PU engeyiyo isocyanate, kunye nezicelo eziguquguqukayo kwiinkalo ezininzi ezahlukeneyo.Umdla kwi-PU wavela ngenxa yendlela yabo elula kunye neprotocol yesicelo, izinto ezilula (ezimbalwa) ezisisiseko kunye neepropati eziphezulu zemveliso yokugqibela.Amacandelo aqhubayo anika inkcazo emfutshane yezinto ezifunekayo kwi-PU synthesis kunye nekhemistri ngokubanzi ebandakanyekayo ekuvelisweni kwePU.
Isibhengezo:Inqaku licatshulwe © 2012 Sharmin kunye noZafar, umntu onikwe ilayisenisi u-InTech.Kuphela ukunxibelelana kunye nokufunda, ungenzi ezinye iinjongo zorhwebo, ayimeli iimbono kunye nezimvo zenkampani, ukuba ufuna ukuphinda uprinte, nceda uqhagamshelane nombhali wokuqala, ukuba kukho ukuphulwa, nceda uqhagamshelane nathi ngokukhawuleza ukwenza ukucima ukusetyenzwa.