Lub luag haujlwm tseem ceeb ntawm cellulose ether hauv mortar

Cellulose ether tuaj yeem txhim kho kev ua haujlwm ntawm cov khib nyiab ntub dej, thiab yog ib qho tseem ceeb ntxiv uas cuam tshuam rau kev tsim kho ntawm mortar. Tsim nyog xaiv ntawm cellulose ethers ntawm ntau yam, txawv viscosities, txawv particle loj, txawv degrees ntawm viscosity thiab ntxiv cov nyiaj yuav muaj txiaj ntsig zoo rau kev txhim kho kev ua haujlwm ntawm cov hmoov qhuav mortar. Tam sim no, ntau cov masonry thiab plastering mortars muaj kev tuav dej tsis zoo, thiab cov dej slurry yuav sib cais tom qab ob peb feeb ntawm kev sawv. Kev tuav dej yog ib qho tseem ceeb ntawm methyl cellulose ether, thiab nws kuj yog ib qho kev ua tau zoo uas ntau lub tsev tsim khoom qhuav-sib xyaw, tshwj xeeb tshaj yog cov nyob rau yav qab teb cov cheeb tsam uas muaj qhov kub thiab txias, ua tib zoo saib xyuas. Cov yam ntxwv uas cuam tshuam rau cov dej tuav cov nyhuv ntawm cov hmoov qhuav qhuav muaj xws li qhov sib ntxiv, viscosity, fineness ntawm cov khoom, thiab qhov kub ntawm qhov chaw siv.

Kev tuav dej ntawm cellulose ether

Hauv kev tsim cov khoom siv hauv tsev, tshwj xeeb tshaj yog cov hmoov qhuav mortar, cellulose ether plays lub luag haujlwm tsis tuaj yeem hloov tau, tshwj xeeb tshaj yog nyob rau hauv kev tsim cov mortar tshwj xeeb (hloov mortar), nws yog ib qho tseem ceeb thiab tseem ceeb tivthaiv. Lub luag haujlwm tseem ceeb ntawm cov dej-soluble cellulose ether hauv mortar feem ntau muaj peb yam, ib qho yog cov dej tuav tau zoo, lwm qhov yog kev cuam tshuam ntawm kev sib xws thiab thixotropy ntawm mortar, thiab qhov thib peb yog kev sib cuam tshuam nrog cov cement. Cov dej tuav cov nyhuv ntawm cellulose ether nyob ntawm qhov nqus dej ntawm lub hauv paus txheej, muaj pes tsawg leeg ntawm mortar, lub thickness ntawm lub mortar txheej, cov dej xav tau ntawm cov mortar, thiab lub sij hawm teem ntawm cov khoom siv. Cov dej tuav ntawm cellulose ether nws tus kheej los ntawm solubility thiab lub cev qhuav dej ntawm cellulose ether nws tus kheej. Raws li peb txhua tus paub, txawm hais tias cov cellulose molecular saw muaj ntau ntawm cov hydratable OH pawg, nws tsis yog soluble hauv dej, vim hais tias cov qauv cellulose muaj ib tug high degree ntawm crystallinity. Lub peev xwm hydration ntawm hydroxyl pawg ib leeg tsis txaus los npog cov hydrogen bonds thiab van der Waals rog ntawm cov molecules. Yog li ntawd, nws tsuas swells tab sis tsis yaj nyob rau hauv dej. Thaum ib qho kev hloov pauv tau nkag mus rau hauv cov saw hlau molecular, tsis yog tsuas yog cov khoom hloov pauv puas tsuaj rau cov saw hlau hydrogen, tab sis kuj tseem cuam tshuam cov interchain hydrogen daim ntawv cog lus raug rhuav tshem vim qhov sib txuas ntawm cov khoom sib hloov ntawm cov saw hlau uas nyob ib sab. Qhov loj dua qhov hloov pauv, qhov kev ncua deb ntawm cov molecules ntau dua. Qhov deb dua. Qhov ntau dua qhov cuam tshuam ntawm kev rhuav tshem hydrogen bonds, cellulose ether ua dej-soluble tom qab cellulose lattice nthuav dav thiab cov tshuaj nkag mus, tsim cov tshuaj viscosity siab. Thaum qhov kub nce siab, cov dej ntawm cov polymer tsis muaj zog, thiab cov dej ntawm cov chains raug tsav tawm. Thaum lub cev qhuav dej txaus, cov molecules pib sib sau ua ke, tsim cov qauv peb-dimensional network gel thiab folded tawm.

Feem ntau hais lus, qhov siab dua qhov viscosity, qhov zoo dua cov dej tuav. Txawm li cas los xij, qhov siab dua qhov viscosity thiab siab dua qhov hnyav molecular, qhov sib piv ntawm nws cov solubility yuav muaj kev cuam tshuam tsis zoo rau lub zog thiab kev tsim kho ntawm cov mortar. Qhov siab dua qhov viscosity, qhov pom tseeb dua cov nyhuv thickening ntawm mortar, tab sis nws tsis ncaj qha proportional. Qhov siab dua qhov viscosity, qhov viscous ntau dua cov mortar ntub yuav, uas yog, thaum lub sij hawm tsim kho, nws yog manifested li sticking rau scraper thiab siab adhesion rau lub substrate. Tab sis nws tsis muaj txiaj ntsig los ua kom lub zog muaj zog ntawm cov mortar ntub nws tus kheej. Thaum lub sij hawm tsim kho, qhov kev ua tau zoo anti-sag tsis pom tseeb. Ntawm qhov tsis sib xws, qee qhov nruab nrab thiab qis viscosity tab sis hloov kho methyl cellulose ethers muaj kev ua tau zoo hauv kev txhim kho lub zog ntawm cov khoom ntub dej.

Thickening thiab Thixotropy ntawm Cellulose Ether

Kuj tseem muaj kev sib raug zoo ntawm kev sib xws ntawm cov cement paste thiab ntau npaum li cas ntawm cellulose ether. Cellulose ether tuaj yeem ua kom cov viscosity ntawm mortar zoo heev. Qhov ntau npaum li cas, qhov pom tseeb dua cov nyhuv. High-viscosity cellulose ether aqueous tov muaj siab thixotropy, uas kuj yog ib tug tseem ceeb yam ntxwv ntawm cellulose ether.

Thickening nyob ntawm qhov degree ntawm polymerization ntawm cellulose ether, kua concentration, shear rate, kub thiab lwm yam mob. Cov cuab yeej gelling ntawm cov tshuaj yog tshwj xeeb rau alkyl cellulose thiab nws cov derivatives hloov. Cov khoom gelation muaj feem xyuam rau qib ntawm kev hloov pauv, tshuaj concentration thiab additives. Rau hydroxyalkyl hloov derivatives, cov khoom gel kuj muaj feem xyuam nrog kev hloov kho qib ntawm hydroxyalkyl. Rau cov viscosity tsawg MC thiab HPMC, 10%-15% tov tuaj yeem npaj tau, nruab nrab viscosity MC thiab HPMC tuaj yeem npaj 5%-10% tov, thaum siab viscosity MC thiab HPMC tsuas tuaj yeem npaj 2%-3% tov, thiab feem ntau Kev faib tawm viscosity ntawm cellulose ether kuj tau muab qhab nia los ntawm 1% -2% tov. Siab molecular hnyav cellulose ether muaj cov thickening efficiency. Nyob rau hauv tib lub concentration tov, polymers nrog sib txawv molecular luj muaj sib txawv viscosities. Qib siab. Lub hom phiaj viscosity tsuas tuaj yeem ua tiav los ntawm kev ntxiv ib qho loj ntawm qhov hnyav molecular cellulose ether. Nws viscosity muaj me ntsis nyob ntawm tus nqi shear, thiab lub siab viscosity ncav cuag lub hom phiaj viscosity, thiab qhov yuav tsum tau ntxiv tus nqi yog me me, thiab viscosity nyob ntawm qhov thickening efficiency. Yog li ntawd, kom ua tiav ib qho kev sib xws, qee qhov ntawm cellulose ether (kev sib xyaw ntawm cov tshuaj) thiab cov tshuaj viscosity yuav tsum tau lav. Cov gel kub ntawm cov tshuaj kuj txo qis linearly nrog qhov nce ntawm cov concentration ntawm cov tshuaj, thiab gels ntawm chav tsev kub tom qab ncav cuag ib tug tej yam concentration. Lub gelling concentration ntawm HPMC yog qhov siab ntawm chav tsev kub.

Retardation ntawm Cellulose Ether

Qhov thib peb ua haujlwm ntawm cellulose ether yog ncua cov txheej txheem dej ntawm cov cement. Cellulose ether endows mortar nrog ntau yam khoom muaj txiaj ntsig, thiab tseem txo qis cov dej thaum ntxov ntawm cov cement thiab ncua cov txheej txheem hydration dynamic ntawm cov cement. Qhov no yog qhov tsis zoo rau kev siv tshuaj khib nyiab hauv thaj chaw txias. Cov nyhuv retardation no yog tshwm sim los ntawm adsorption ntawm cellulose ether molecules ntawm hydration khoom xws li CSH thiab ca (OH) 2. Vim qhov nce hauv qhov viscosity ntawm cov pore tov, cellulose ether txo qhov kev txav ntawm ions hauv cov tshuaj, yog li ncua cov txheej txheem hydration. Qhov siab dua qhov concentration ntawm cellulose ether nyob rau hauv cov ntxhia gel cov ntaub ntawv, ntau pronounced cov nyhuv ntawm hydration ncua. Cellulose ether tsis tsuas yog ncua kev teeb tsa, tab sis tseem ncua cov txheej txheem hardening ntawm cov cement mortar system. Cov nyhuv retarding ntawm cellulose ether nyob ntawm tsis tsuas yog nyob rau hauv nws cov concentration nyob rau hauv cov ntxhia gel system, tab sis kuj nyob rau hauv cov tshuaj. Qhov siab dua qib ntawm methylation ntawm HEMC, qhov zoo dua qhov cuam tshuam ntawm cellulose ether. Qhov piv ntawm hydrophilic hloov pauv mus rau kev hloov pauv dej nce ntxiv Cov nyhuv retarding muaj zog dua. Txawm li cas los xij, viscosity ntawm cellulose ether tsis tshua muaj txiaj ntsig rau cov cement hydration kinetics.

Nyob rau hauv mortar, cellulose ether plays lub luag hauj lwm ntawm cov dej tuav, thickening, ncua cov cement hydration zog, thiab txhim kho kev tsim kho. Lub peev xwm tuav dej zoo ua rau cov cement hydration ntau dua, tuaj yeem txhim kho cov viscosity ntawm cov khib nyiab ntub dej, ua kom lub zog sib txuas ntawm mortar, thiab kho lub sijhawm. Ntxiv cellulose ether rau cov neeg kho tshuab txau mortar tuaj yeem txhim kho cov tshuaj txau lossis kev ua haujlwm thiab kev ua haujlwm ntawm cov tshuaj khib nyiab. Yog li ntawd, cellulose ether tau dav siv los ua ib qho tseem ceeb additive nyob rau hauv npaj sib tov mortar