Cellulose ether yog ib qho hluavtaws polymer ua los ntawm ntuj cellulose los ntawm kev hloov tshuaj lom neeg. Cellulose ether yog derivative ntawm natural cellulose. Kev tsim cov cellulose ether yog txawv los ntawm hluavtaws polymers. Nws cov khoom siv yooj yim tshaj plaws yog cellulose, lub ntuj polymer compound. Vim qhov tshwj xeeb ntawm cov qauv cellulose, cellulose nws tus kheej tsis muaj peev xwm ua rau cov tshuaj etherification. Txawm li cas los xij, tom qab kev kho mob ntawm tus neeg mob o, lub zog hydrogen bonds ntawm cov saw hlau molecular thiab cov chains raug rhuav tshem, thiab cov active tso tawm ntawm pawg hydroxyl los ua reactive alkali cellulose. Tau txais cellulose ether.
Hauv kev npaj sib tov mortar, qhov sib ntxiv ntawm cellulose ether yog tsawg heev, tab sis nws tuaj yeem txhim kho kev ua haujlwm ntawm cov khib nyiab ntub dej, thiab nws 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 cuam tshuam rau cov dej tuav cov nyhuv ntawm cov tshuaj khib nyiab qhuav suav nrog cov nyiaj MC ntxiv, qhov viscosity ntawm MC, qhov zoo ntawm cov khoom thiab qhov kub ntawm qhov chaw siv.
Cov khoom ntawm cellulose ethers nyob ntawm seb hom, tus lej thiab kev faib tawm ntawm cov khoom hloov pauv. Kev faib tawm ntawm cellulose ethers kuj yog nyob ntawm hom kev hloov pauv, qib ntawm etherification, solubility thiab lwm yam khoom siv. Raws li hom kev hloov pauv ntawm cov saw hlau molecular, nws tuaj yeem muab faib ua monoether thiab sib xyaw ether. MC peb feem ntau siv yog monoether, thiab HPMC yog sib xyaw ether. Methyl cellulose ether MC yog cov khoom lag luam tom qab pawg hydroxyl ntawm cov piam thaj hauv cov cellulose ntuj hloov los ntawm methoxy. Cov qauv tsim qauv yog [COH7O2(OH)3-h(OCH3)h]x. Ib feem ntawm pawg hydroxyl ntawm chav tsev yog hloov los ntawm pawg methoxy, thiab lwm qhov yog hloov los ntawm pawg hydroxypropyl, cov qauv qauv yog [C6H7O2(OH) 3-mn(OCH3)m[OCH2CH(OH)CH3] n]x Ethyl methyl cellulose ether HEMC ntau yam muag.
Nyob rau hauv cov nqe lus ntawm solubility, nws yuav muab faib ua ionic thiab non-ionic. Dej-soluble non-ionic cellulose ethers yog tsim los ntawm ob series ntawm alkyl ethers thiab hydroxyalkyl ethers. Ionic CMC feem ntau yog siv rau hauv cov khoom siv hluavtaws, textile printing thiab dyeing, zaub mov thiab roj tshawb nrhiav. Non-ionic MC, HPMC, HEMC, thiab lwm yam yog siv rau hauv cov khoom siv hauv tsev, latex coatings, tshuaj, tshuaj txhua hnub, thiab lwm yam. Siv ua thickener, dej tuav tus neeg saib xyuas, stabilizer, dispersant thiab zaj duab xis tsim tus neeg sawv cev.
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 cov khoom tshwj xeeb mortar (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:
1. Cov dej tuav tau zoo heev
2. Cov nyhuv ntawm mortar sib xws thiab thixotropy
3. 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.
Post lub sij hawm: Dec-06-2022