Ukwakheka kwamakhemikhali oketshezi-kokubili okunamagwebu okuyingxenye ngokuvamile ukwakhiwa kwengxenye A (ingxenye ye-isocyanate) kanye nengxenye B (ingxenye ye-polyol). Ngemva kokuxuba, lezi zingxenye ezimbili zisabela ukuze zenze igwebu. Okulandelayo ukuhlaziya okuqondile:
1.Ingxenye A (ingxenye ye-isocyanate)
• Izingxenye eziyinhloko: i-polyisocyanates, evame kakhulu i-toluene diisocyanate (TDI) ne-diphenylmethane diisocyanate (MDI), ngaphezu kwe-polymeric MDI (PAPI).
• Umsebenzi: "Njenge-ejenti exhumanisayo" yokusabela, ihlangana neqembu le-hydrogen esebenzayo engxenyeni B futhi iwumgogodla wempahla esetshenziselwa ukwakheka kwesakhiwo segwebu.
2.Ingxenye B (ingxenye ye-polyol)
Iqukethe izinhlobonhlobo zezingxenye ezibamba iqhaza ekuphenduleni futhi zilawule izakhiwo zegwebu:
• Ama-Polyols: afana ne-polyether polyol ne-polyester polyol, ahlinzeka nge-hydroxyl (-OH) futhi ahlangane-neqembu le-NCO le-isocyanate, akha isisekelo sohlaka lwamathambo egwebu.
• I-ejenti ekhiqiza amagwebu: ikhiqiza igesi ukuze kwandiswe ingxube nokwenza amabhamuza. Ezivamile izinto ezikhipha amagwebu ngokomzimba (isb., izibambela ze-Freon, i-cyclopentane) kanye namagwebu amakhemikhali (isb, amanzi, ahlangana ne-isocyanate ukuze akhiqize isikhutha).
• I-Catalyst: Isheshisa ukusabela, njenge-amine catalyst (ithuthukisa ukusabela okukhihliza amagwebu) kanye ne-organotin catalyst (ithuthukisa ukusabela kwejeli).
• Ama-surfactants: zinzisa ukwakheka kwegwebu futhi uvimbele ukuthi igwebu lingaqhumi. Ngokuvamile ziyizinhlanganisela ze-siloxane.
• Ezinye izithasiselo: njengama-flame retardants, ama-fillers, ama-colorants, njll, anezelwa ngokuvumelana nezidingo zohlelo lokusebenza ukuthuthukisa i-flame retardant, amandla nezinye izakhiwo zegwebu.
3.Isimiso Sokusabela
Uma izingxenye A no-B zixutshwa, amaqembu e-NCO e-isocyanate asabela-ngamaqembu e-OH ama-polyols namanzi, adedele igesi (ephuphumayo) ukuze akhe into eyigwebu enezimbotshana. Izilinganiso ezithile kanye nezinhlobo zezingxenye zinquma ukuminyana kwegwebu, ukuqina, izakhiwo zokufaka ukushisa okushisayo, nezinye izici. Lokhu kwaziswa okuguquguqukayo kuthola ukusetshenziswa okubanzi kumasistimu okufakwa ngaphakathi, izixazululo zokupakisha, ukukhiqizwa kwefenisha, kanye nezimboni ezihlobene.