Dzina la malonda:polyurethane

Kapangidwe kazinthu zama cell:

Chemical Properties:

Ma polyurethanes adapangidwa koyamba ndikufufuzidwa ndi Dr. Otto Bayer mu 1937. Polyurethane ndi polima momwe gawo lobwereza limakhala ndi urethane moiety.Urethanes ndi zotumphukira za ma carbamic acid omwe amapezeka mwa mawonekedwe a esters awo[15].Ubwino waukulu wa PU ndikuti unyolowu supangidwa ndi maatomu a kaboni okha koma m'malo mwa ma heteroatomu, oxygen, carbon ndi nitrogen[4].Pogwiritsa ntchito mafakitale, polyhydroxyl pawiri ingagwiritsidwe ntchito.Mofananamo, mankhwala a nayitrogeni a poly-functional atha kugwiritsidwa ntchito polumikizana ndi amide.Posintha ndikusintha ma polyhydroxyl ndi polyfunctional nitrogen compounds, ma PU osiyanasiyana amatha kupangidwa [15].Ma polyester kapena polyether resins okhala ndi magulu a hydroxyl amagwiritsidwa ntchito kupanga polyesteror polyether-PU, motsatana [6].Kusiyanasiyana kwa kuchuluka kwa zolowa m'malo ndi kagawidwe pakati ndi mkati mwa unyolo wanthambi kumatulutsa ma PU kuyambira mzere mpaka nthambi ndi 9exible mpaka olimba.Linear PUs amagwiritsidwa ntchito popanga ulusi ndi kuumba[6].Flexible PUs amagwiritsidwa ntchito popanga zomangira ndi zokutira[5].Mapulasitiki osinthika komanso olimba a thovu, omwe amapanga ma PU ambiri opangidwa, amapezeka m'njira zosiyanasiyana m'makampani[7].Pogwiritsa ntchito ma prepolymer otsika a cell, ma copolymer osiyanasiyana amatha kupangidwa.Gulu la terminal la hydroxyl limalola kuti midadada yosinthira, yotchedwa magawo, kuti ayikidwe mu unyolo wa PU.Kusiyanasiyana m'magawo awa kumabweretsa milingo yosiyanasiyana yamphamvu yamphamvu komanso kukhazikika.Midawu yopereka gawo lolimba la crystalline komanso yokhala ndi chain extender imatchedwa magawo olimba[7].Zomwe zimapatsa gawo la amorphous rubbery ndipo zimakhala ndi polyester / polyether amatchedwa zigawo zofewa.Pazamalonda, ma polima a block awa amadziwika kuti Segmented Pus

Ntchito:

Polyurethanes ndi chimodzi mwazinthu zosunthika kwambiri padziko lapansi masiku ano.Ntchito zawo zambiri zimachokera ku thovu losinthika mumipando yokwezeka, mpaka thovu lolimba ngati zotchingira m'makoma, madenga ndi zida zamagetsi ku thermoplastic polyurethane yomwe imagwiritsidwa ntchito pazida zamankhwala ndi nsapato, mpaka zokutira, zomatira, zosindikizira ndi ma elastomer omwe amagwiritsidwa ntchito pansi ndi mkati mwagalimoto [17,18] ].Ma polyurethanes akhala akugwiritsidwa ntchito kwambiri m'zaka makumi atatu zapitazi m'njira zosiyanasiyana chifukwa cha chitonthozo chawo, phindu lamtengo wapatali, kupulumutsa mphamvu komanso kumveka bwino kwa chilengedwe.Kodi ndi zinthu ziti zomwe zimapangitsa polyurethane kukhala yofunikira kwambiri?Kukhazikika kwa polyurethane kumathandizira kwambiri pazaka zambiri zamoyo wazinthu zambiri.Kuwonjezedwa kwa moyo wazinthu zopangira ndi kusungirako zinthu ndizofunikira kwambiri pazachilengedwe zomwe nthawi zambiri zimakonda kusankha ma polyurethanes[19-21].Ma polyurethanes (PU) amayimira gulu lofunikira la ma polima a thermoplastic ndi thermoset monga makina awo, matenthedwe, ndi mankhwala amatha kupangidwa mogwirizana ndi ma polyols osiyanasiyana ndi ma poly-isocyanates.