Mbiri ya polyurethane

Kupezeka kwa polyurethane [PU] kudayamba mchaka cha 1937 ndi Otto Bayer ndi ogwira nawo ntchito ku ma laboratories a IG Farben ku Leverkusen, Germany.Ntchito zoyambazo zimayang'ana kwambiri pa zinthu za PU zopezedwa kuchokera ku aliphatic diisocyanate ndi diamine kupanga polyurea, mpaka zinthu zosangalatsa za PU zopezedwa kuchokera ku aliphatic diisocyanate ndi glycol, zidakwaniritsidwa.Ma Polyisocyanates adayamba kupezeka pamalonda mchaka cha 1952, patangopita nthawi yochepa kuti malonda a PU awonekere (itatha Nkhondo Yachiwiri Yapadziko Lonse) kuchokera ku toluene diisocyanate (TDI) ndi polyester polyols.M'zaka zotsatira (1952-1954), machitidwe osiyanasiyana a polyester-polyisocyanate anapangidwa ndi Bayer.
Ma polyester polyols adasinthidwa pang'onopang'ono ndi ma polyether polyols chifukwa cha zabwino zake zingapo monga mtengo wotsika, kusavuta kugwira, komanso kukhazikika kwa hydrolytic kuposa zakale.Poly(tetramethylene ether) glycol (PTMG), idayambitsidwa ndi DuPont mu 1956 ndi polymerizing tetrahydrofuran, monga polyether polyether polyol yoyamba kugulitsidwa.Pambuyo pake, mu 1957, BASF ndi Dow Chemical anapanga polyalkylene glycols.Kutengera PTMG ndi 4,4'-diphenylmethane diisocyanate (MDI), ndi ethylene diamine, Spandex ulusi wotchedwa Lycra anapangidwa ndi Dupont.Pazaka makumi angapo, PU adamaliza maphunziro a PU foams (1960) mpaka PU foams (polyisocyanurate foams-1967) ngati zida zingapo zowombera, polyether polyols, ndi polymeric isocyanate monga poly methylene diphenyl diisocyanate (PMDI) idapezeka.Ma foam a PU a PMDI awa adawonetsa kukana kwabwino kwamafuta komanso kuchepa kwamoto.
Mu 1969, ukadaulo wa PU Reaction Injection Molding [PU RIM] udayambitsidwa womwe udapita patsogolo mu Reinforced Reaction Injection Molding [RRIM] kupanga zida za PU zomwe mu 1983 zidatulutsa galimoto yoyamba yamapulasitiki ku United States.M'zaka za m'ma 1990, chifukwa cha kukwera kwa chidziwitso chokhudza kuopsa kogwiritsa ntchito ma chloro-alkanes ngati owombera (Montreal protocol, 1987), zida zina zingapo zophulitsa zidatulutsidwa pamsika (mwachitsanzo, carbon dioxide, pentane, 1,1,1,2- tetrafluoroethane, 1,1,1,3,3-pentafluoropropane).Nthawi yomweyo, ukadaulo wapaketi wapaketi wa PU, PU-polyurea wopaka utoto udayamba kuwoneratu, womwe unali ndi zabwino zambiri zokhala osakhudzidwa ndi chinyezi ndikuchitanso mwachangu.Kenako idaphuka njira yogwiritsira ntchito mafuta a masamba opangidwa ndi polyols popanga PU.Masiku ano, dziko la PU lachokera kutali ndi ma hybrids a PU, ma PU composites, non-isocyanate PU, okhala ndi ntchito zosunthika m'magawo angapo osiyanasiyana.Zokonda za PU zidayamba chifukwa cha kuphatikizika kwawo kosavuta komanso njira yogwiritsira ntchito, zosavuta (zochepa) zoyambira zoyambira komanso zabwino kwambiri pazomaliza.Magawo omwe akukambidwawo amafotokoza mwachidule za zida zomwe zimafunikira mu kaphatikizidwe ka PU komanso chemistry yomwe imakhudzidwa ndi kupanga PU.
Chidziwitso:Nkhaniyi idalembedwa © 2012 Sharmin ndi Zafar, yemwe ali ndi chilolezo InTech.Pokhapokha kuyankhulana ndi kuphunzira, osachita zina zamalonda, sikuyimira maganizo ndi malingaliro a kampani, ngati mukufuna kusindikizanso, chonde funsani wolemba woyambirira, ngati pali kuphwanya, chonde tilankhule nafe nthawi yomweyo kuti tichite kukonza.


Nthawi yotumiza: Dec-12-2022