Khoom cua roj hmab ntau lawm

Cov hluavtaws elastomers yog tsim rau ntawm kev ntsuas hauv kev lag luam hauv kev daws lossis emulsion polymerization. ( Cov tshuaj polymerization thiab emulsion polymerization tau piav qhia hauv tsab xov xwm txog kev lag luam muaj cov tshuaj polymers .) Cov tshuaj pleev ua haujlwm hauv cov tshuaj feem ntau muaj cov kab tawm ntau dua (uas yog, muaj tsawg dua cov ceg ntawm sab txuas los ntawm lub ntsiab xov polymer ), thiab lawv kuj muaj qhov sib faib ntawm cov qauv sib txawv. qhov hnyav (uas yog, ntev dua) thiab ntws yooj yim dua. Ntxiv rau, qhov kev tso kawm ntawm cov monomer units hauv lub polymer molecule tuaj yeem tswj tau ntau dua qhov tseeb thaum cov tshuaj polymerization tau ua hauv kev daws teeb meem. Lub monomer lossis monomers yog yaj hauv hydrocarbon solvent, feem ntau hexane lossis cyclohexane, thiab polymerized, siv cov organometallic catalyst xws li butyllithium.

Hauv emulsion polymerization , cov monomer (lossis monomers) yog emulsified hauv dej nrog cov xab npum tsim nyog (piv txwv li sodium stearate) ua haujlwm ua surfactant , thiab dej-soluble dawb-radical catalyst (piv txwv li, potassium persulfate, peroxides, lub redox system) yog ntxiv rau induce polymerization. Tom qab polymerization tau mus txog qib qhov xav tau, cov tshuaj tiv thaiv raug tso tseg los ntawm kev ntxiv ib radical inhibitor. Txog 10 feem pua ntawm cov hluavtaws elastomer uas ua los ntawm cov txuj ci emulsion raug muag ua cov latex . Tus so yog coagulated nrog acidified brine, ntxuav, qhuav, thiab nias rau hauv 35-kg (77-phaus) bales.

Daim duab ntawm daim duab emulsion-polymerization qauv. Monomer lwg me me thiab cov kev pub dawb-tshaj dhau ntxiv tau ntxiv rau cov dej-ua emulsion da dej nrog rau cov ntaub soaplike hu ua surfactants, lossis cov neeg sawv cev ua haujlwm saum npoo av. Lub surfactant lwg me me, tsim los ntawm hydrophilic (dej-txaus nyiam) thiab hydrophobic (dej-pleev xim) kawg, ua rau lub zog emulsion ua ntej polymerization los ntawm txheej cov monomer mob. Lwm cov surfactant lwg me me sib dhos ua ke rau hauv cov khoom sib txuas me dua hu ua micelles, uas tseem nqus cov pa roj carbon monomer. Polymerization tshwm sim thaum thawj kauj ruam tsiv mus rau hauv cov micelles, ua rau lub monomer lwg me me los ua cov qauv loj uas tsim cov xim ua kua. Encyclopædia Britannica, Inc.

Thaum cov emulsion polymerization ntawm SBR nqa tawm "kub" (piv txwv li ntawm 50 ° C, lossis 120 ° F), cov kua roj polymer polymer ntau dua cov ceg. Thaum polymerization yog nqa tawm "txias" (piv txwv li, ntawm 5 ° C, lossis 40 ° F), lawv yog cov kab ntau dua thiab feem ntau siab dua hauv cov phaus nyhav-cov yam ntxwv uas txhim kho cov ntxuag kuj thiab hnav tsis kam ntawm cov log tsheb. Qee qhov xwm txheej polymerization txuas txuas ntxiv txhawm rau muab cov khoom lag luam ntawm cov muaj qhov hnyav molecular uas lawv ib txwm yuav dhau los ua kev cuam tshuam. Hauv cov xwm txheej no kwv yees li 30 feem pua ntawm cov roj hnyav tau ntxiv ua ntej coagulation kom cov pa "roj-txuas" elastomers nrog kev hnav zoo dua