Abubuwan da ke ɗauke da yawan ƙungiyoyin hydroxyl ana kiran su spolyols.Hakanan suna iya ƙunsar ester, ether, amide, acrylic, ƙarfe, metalloid da sauran ayyuka, tare da ƙungiyoyin hydroxyl.Polyester polyols (PEP) sun ƙunshi ester da ƙungiyoyin hydroxylic a cikin kashin baya ɗaya.Gabaɗaya ana shirya su ta hanyar yanayin daɗaɗɗa tsakanin glycols, watau,
ethylene glycol, 1,4-butane diol, 1,6-hexane diol da dicarboxylic acid / anhydride (aliphatic Polyurethane: Gabatarwa 7 ko aromatic).Kaddarorin PU kuma sun dogara da matakin haɗin giciye da kuma nauyin kwayoyin halittar PEP na farawa.Duk da yake babban reshe PEP yana haifar da PU mai tsauri tare da zafi mai kyau da juriya na sinadarai, ƙarancin PEP yana ba da PU tare da sassauci mai kyau (a ƙananan zafin jiki) da ƙarancin juriya na sinadarai.Hakazalika, ƙananan nau'in polyols suna haifar da tsayayyen PU yayin da babban nauyin kwayoyin dogon sarkar polyols suna haifar da PU mai sassauƙa.Kyakkyawan misali na PEP da ke faruwa a zahiri shine man Castor.Sauran man kayan lambu (VO) ta hanyar canjin sinadarai kuma suna haifar da PEP.PEP suna da saukin kamuwa da hydrolysis saboda kasancewar
ƙungiyoyin ester, kuma wannan kuma yana haifar da tabarbarewar kayan aikinsu.Ana iya shawo kan wannan matsala ta hanyar ƙara ƙananan adadin carbodiimides.Polyether polyols (PETP) ba su da tsada fiye da PEP.Ana samar da su ta hanyar ƙari na ethylene ko propylene oxide tare da barasa ko amine masu farawa ko masu ƙaddamarwa a gaban mai haɓaka acid ko tushe.PU da aka haɓaka daga PETP suna nuna ƙarancin danshi da ƙarancin Tg, wanda ke iyakance yawan amfani da su a cikin sutura da fenti.Wani misali na polyols shine acrylated polyol (ACP) wanda aka yi ta hanyar polymerization na kyauta na hydroxyl ethyl acrylate/methacrylate tare da sauran acrylics.ACP yana samar da PU tare da ingantaccen yanayin zafi kuma yana ba da halaye na yau da kullun na acrylics zuwa sakamakon PU.Waɗannan PU suna samun aikace-aikace azaman kayan shafa.Polyols an ƙara gyaggyarawa da ƙarfe gishiri (misali, ƙarfe acetates, carboxylates, chlorides) kafa karfe dauke da polyols ko hybrid polyols (MHP).PU da aka samu daga MHP yana nuna kyakkyawan kwanciyar hankali na thermal, kyalkyali da halayen anti-microbial.Littattafai sun ba da rahoton misalai da yawa na tushen PEP, PETP, ACP, MHP da aka yi amfani da su azaman kayan shafa na PU.Wani misali shine VO wanda aka samo fatty amide diols da polyols (wanda aka kwatanta daki-daki a cikin babi na 20 Seed oil based polyurethanes: wani fahimta), wanda yayi aiki a matsayin mai kyau.
kayan farawa don haɓaka PU.Wadannan PU sun nuna kyakkyawan kwanciyar hankali na thermal da juriya na hydrolytic saboda kasancewar ƙungiyar amide a cikin diol ko polyol kashin baya.

Sanarwa:An nakalto labarin © 2012 Sharmin and Zafar, mai lasisi InTech.Sai kawai don sadarwa da koyo, kada ku yi wasu dalilai na kasuwanci, baya wakiltar ra'ayi da ra'ayoyin kamfanin, idan kuna buƙatar sake bugawa, tuntuɓi marubucin asali, idan akwai ƙetare, da fatan za a tuntuɓe mu nan da nan don yin sharewa.