Cellulose ether yog cov ntsiab lus dav dav rau cov khoom lag luam uas tsim los ntawm cov tshuaj tiv thaiv ntawm alkali cellulose thiab etherifying tus neeg sawv cev nyob rau hauv qee yam mob. Alkali cellulose yog hloov los ntawm cov neeg ua haujlwm sib txawv kom tau txais cov cellulose ethers sib txawv. Raws li cov khoom ionization ntawm cov khoom hloov, cellulose ethers tuaj yeem muab faib ua ob pawg: ionic (xws li carboxymethyl cellulose) thiab nonionic (xws li methyl cellulose). Raws li hom kev hloov pauv, cellulose ether tuaj yeem muab faib ua monoether (xws li methyl cellulose) thiab sib xyaw ether (xws li hydroxypropyl methyl cellulose). Raws li qhov sib txawv solubility, nws tuaj yeem muab faib ua dej solubility (xws li hydroxyethyl cellulose) thiab organic solvent solubility (xws li ethyl cellulose). Qhuav-sib xyaw mortar feem ntau yog dej-soluble cellulose, thiab dej-soluble cellulose muab faib ua hom instant thiab deg-kho ncua-dissolution hom.
Lub mechanism ntawm kev txiav txim ntawm cellulose ether nyob rau hauv mortar yog raws li nram no:
(1) Tom qab cov cellulose ether nyob rau hauv lub mortar yog yaj nyob rau hauv dej, qhov zoo thiab niaj hnub faib ntawm cov cementitious cov ntaub ntawv nyob rau hauv lub system yog guaranteed vim lub nto nto, thiab cellulose ether, raws li ib tug tiv thaiv colloid, "wraps" cov khoom. cov khoom thiab Ib txheej ntawm lubricating zaj duab xis yog tsim rau ntawm nws sab nrauv, uas ua rau cov mortar system ruaj khov, thiab tseem txhim kho cov kua dej ntawm cov mortar thaum lub sij hawm sib tov thiab smoothness ntawm kev tsim kho.
(2) Vim nws tus yam ntxwv ntawm cov qauv molecular, cov tshuaj cellulose ether ua rau cov dej noo hauv cov khib nyiab tsis yooj yim ploj, thiab maj mam tso tawm rau lub sijhawm ntev, ua rau cov mortar nrog dej tuav thiab ua haujlwm tau zoo.
1. Methylcellulose: (MC)
Tom qab cov paj rwb refined yog kho nrog alkali, cellulose ether yog tsim los ntawm ib tug series ntawm cov tshuaj tiv thaiv nrog methane chloride ua etherification tus neeg sawv cev. Feem ntau, qhov degree ntawm kev hloov pauv yog 1.6 ~ 2.0, thiab cov solubility kuj txawv nrog ntau qib kev hloov pauv. Nws belongs rau non-ionic cellulose ether.
(1) Methylcellulose yog soluble hauv dej txias, thiab nws yuav nyuaj rau yaj hauv dej kub. Nws cov tshuaj aqueous yog ruaj khov nyob rau hauv thaj tsam ntawm pH = 3 ~ 12. Nws muaj kev sib raug zoo nrog cov hmoov txhuv nplej siab, cov pos hniav, thiab lwm yam thiab ntau surfactants. Thaum qhov kub nce mus txog qhov kub thiab txias, gelation tshwm sim.
(2) Cov dej tuav ntawm methyl cellulose nyob ntawm nws cov nyiaj ntxiv, viscosity, particle fineness thiab dissolution tus nqi. Feem ntau, yog tias qhov sib ntxiv yog qhov loj, qhov zoo me me, thiab cov viscosity loj, cov dej tuav tau siab. Ntawm lawv, qhov sib ntxiv muaj qhov cuam tshuam loj tshaj plaws ntawm cov dej tuav tus nqi, thiab qib ntawm viscosity tsis ncaj qha mus rau theem ntawm cov dej tuav tus nqi. Tus nqi dissolution feem ntau yog nyob ntawm qhov kev hloov kho saum npoo ntawm cellulose hais thiab particle fineness. Ntawm cov cellulose ethers saum toj no, methyl cellulose thiab hydroxypropyl methyl cellulose muaj cov dej tuav ntau dua.
(3) Kev hloov ntawm qhov kub thiab txias yuav cuam tshuam rau cov dej tuav tus nqi ntawm methyl cellulose. Feem ntau, qhov kub thiab txias dua, qhov dej khaws cia tsis zoo. Yog hais tias lub mortar kub siab tshaj 40 ° C, cov dej tuav ntawm methyl cellulose yuav txo qis, cuam tshuam rau kev tsim kho ntawm mortar.
(4) Methyl cellulose muaj qhov cuam tshuam loj rau kev tsim kho thiab cohesion ntawm mortar. Qhov "adhesiveness" ntawm no yog hais txog kev sib koom ua ke ntawm cov neeg ua haujlwm cov cuab yeej siv thiab cov phab ntsa substrate, uas yog, shear resistance ntawm lub mortar. Lub adhesiveness yog siab, shear resistance ntawm lub mortar yog loj, thiab lub zog yuav tsum tau los ntawm cov neeg ua hauj lwm nyob rau hauv tus txheej txheem ntawm kev siv kuj loj, thiab kev tsim kho ntawm lub mortar yog tsis zoo. Kev sib koom ua ke ntawm methyl cellulose yog nyob rau theem nruab nrab hauv cellulose ether cov khoom.
2. Hydroxypropyl methyl cellulose (HPMC):
Hydroxypropyl methylcellulose yog ib hom cellulose uas nws cov zis thiab kev noj tau nce zuj zus nyob rau xyoo tas los no. Nws yog non-ionic cellulose tov ether ua los ntawm refined paj rwb tom qab alkalization, siv propylene oxide thiab methyl chloride ua etherification tus neeg sawv cev, los ntawm ib tug series ntawm cov tshuaj tiv thaiv. Qhov kev hloov pauv feem ntau yog 1.2 ~ 2.0. Nws cov khoom sib txawv nyob ntawm qhov piv ntawm cov ntsiab lus methoxyl rau hydroxypropyl cov ntsiab lus.
(1) Hydroxypropyl methylcellulose yog yooj yim soluble nyob rau hauv dej txias, thiab nws yuav ntsib teeb meem nyob rau hauv dissolving nyob rau hauv dej kub. Tab sis nws qhov kub thiab txias hauv dej kub yog siab dua li ntawm methyl cellulose. Lub solubility hauv dej txias kuj zoo heev piv nrog methyl cellulose.
(2) Lub viscosity ntawm hydroxypropyl methylcellulose muaj feem xyuam rau nws qhov hnyav molecular, thiab qhov loj dua qhov hnyav molecular, qhov viscosity siab dua. Kub kuj cuam tshuam rau nws cov viscosity, thaum kub nce, viscosity txo. Txawm li cas los xij, qhov cuam tshuam ntawm nws cov viscosity siab thiab kub yog qis dua li ntawm methyl cellulose. Nws cov tshuaj yog ruaj khov thaum khaws cia ntawm chav tsev kub.
(3) Cov dej tuav ntawm hydroxypropyl methylcellulose nyob ntawm nws qhov sib ntxiv, viscosity, thiab lwm yam, thiab nws cov dej tuav tus nqi nyob rau hauv tib qhov sib ntxiv yog siab dua li ntawm methyl cellulose.
(4) Hydroxypropyl methylcellulose ruaj khov rau cov kua qaub thiab alkali, thiab nws cov tshuaj aqueous yog ruaj khov nyob rau hauv thaj tsam ntawm pH = 2 ~ 12. Caustic soda thiab txiv qaub dej tsis tshua muaj txiaj ntsig rau nws qhov kev ua tau zoo, tab sis alkali tuaj yeem ua kom nws tawg thiab ua kom nws viscosity me ntsis. Hydroxypropyl methylcellulose yog ruaj khov rau cov ntsev ntau, tab sis thaum lub concentration ntawm ntsev tov yog siab, lub viscosity ntawm hydroxypropyl methylcellulose tov nyhav nce.
(5) Hydroxypropyl methylcellulose tuaj yeem sib xyaw nrog cov dej-soluble polymer compounds los ua ib qho kev daws teeb meem thiab siab dua viscosity. Xws li polyvinyl cawv, starch ether, zaub pos hniav, thiab lwm yam.
(6) Hydroxypropyl methylcellulose muaj enzyme zoo dua li methylcellulose, thiab muaj peev xwm ntawm enzymatic degradation ntawm nws cov tshuaj yog qis dua li ntawm methylcellulose.
(7) Lub adhesion ntawm hydroxypropyl methylcellulose rau mortar siv yog siab dua li ntawm methylcellulose.
3. Hydroxyethyl cellulose (HEC):
Nws yog tsim los ntawm refined paj rwb kho nrog alkali, thiab reacted nrog ethylene oxide raws li etherification tus neeg sawv cev nyob rau hauv lub xub ntiag ntawm acetone. Nws qhov kev hloov pauv feem ntau yog 1.5 ~ 2.0. Nws muaj zog hydrophilicity thiab yooj yim rau nqus noo noo.
(1) Hydroxyethyl cellulose yog soluble hauv dej txias, tab sis nws nyuaj rau yaj hauv dej kub. Nws cov tshuaj yog ruaj khov ntawm qhov kub thiab txias yam tsis muaj gelling. Nws tuaj yeem siv tau ntev hauv qhov kub thiab txias hauv mortar, tab sis nws cov dej tuav qis dua li ntawm methyl cellulose.
(2) Hydroxyethyl cellulose ruaj khov rau cov kua qaub thiab alkali. Alkali tuaj yeem ua kom nrawm nrawm rau nws qhov kev sib cais thiab ua kom nws cov viscosity me ntsis. Nws dispersibility hauv dej yog me ntsis phem dua li ntawm methyl cellulose thiab hydroxypropyl methyl cellulose. .
(3) Hydroxyethyl cellulose muaj kev ua haujlwm zoo los tiv thaiv mortar, tab sis nws muaj sijhawm ntev dua rau cov cement.
(4) Kev ua tau zoo ntawm hydroxyethyl cellulose ua los ntawm qee lub tuam txhab hauv tsev yog qis dua li ntawm methyl cellulose vim nws cov ntsiab lus dej siab thiab cov hmoov tshauv siab.
4. Carboxymethyl cellulose (CMC):
Ionic cellulose ether yog tsim los ntawm ntuj fibers (paj rwb, thiab lwm yam) tom qab kev kho alkali, siv sodium monochloroacetate ua tus neeg sawv cev etherification, thiab tau txais kev kho cov tshuaj tiv thaiv. Qib ntawm kev hloov pauv feem ntau yog 0.4 ~ 1.4, thiab nws qhov kev ua tau zoo cuam tshuam los ntawm qib hloov pauv.
(1) Carboxymethyl cellulose yog hygroscopic ntau dua, thiab nws yuav muaj dej ntau dua thaum khaws cia rau hauv cov xwm txheej.
(2) Carboxymethyl cellulose aqueous tov yuav tsis tsim gel, thiab viscosity yuav txo nrog qhov kub thiab txias. Thaum qhov kub siab tshaj 50 ° C, viscosity yog irreversible.
(3) Nws ruaj khov heev cuam tshuam los ntawm PH. Feem ntau, nws tuaj yeem siv rau hauv gypsum-raws li mortar, tab sis tsis yog hauv cov cement-based mortar. Thaum alkaline heev, nws yuav poob viscosity.
(4) Nws cov dej tuav tau qis dua li ntawm methyl cellulose. Nws muaj cov nyhuv retarding ntawm gypsum-raws li mortar thiab txo nws lub zog. Txawm li cas los xij, tus nqi ntawm carboxymethyl cellulose yog qis dua li ntawm methyl cellulose.
Post lub sij hawm: Feb-27-2023