Cellulose ether yog ib qho polymer hluavtaws ua los ntawm cov cellulose ntuj los ntawm kev hloov kho tshuaj. Cellulose ether yog ib qho derivative ntawm cellulose ntuj. Kev tsim cov cellulose ether txawv ntawm cov polymers hluavtaws. Nws cov khoom siv yooj yim tshaj plaws yog cellulose, ib qho tshuaj polymer ntuj. Vim yog qhov tshwj xeeb ntawm cov qauv cellulose ntuj, cellulose nws tus kheej tsis muaj peev xwm los cuam tshuam nrog cov neeg sawv cev etherification. Txawm li cas los xij, tom qab kev kho mob ntawm tus neeg sawv cev o, cov hydrogen bonds muaj zog ntawm cov saw hlau molecular thiab cov saw hlau raug rhuav tshem, thiab kev tso tawm ntawm pawg hydroxyl ua rau cov alkali cellulose reactive. Tau txais cellulose ether.
Hauv cov tshuaj mortar sib xyaw ua ke, qhov ntxiv ntawm cellulose ether tsawg heev, tab sis nws tuaj yeem txhim kho qhov ua tau zoo ntawm cov tshuaj mortar ntub, thiab nws yog ib qho khoom ntxiv tseem ceeb uas cuam tshuam rau kev ua tau zoo ntawm cov tshuaj mortar. Kev xaiv cov cellulose ethers ntawm ntau hom sib txawv, viscosities sib txawv, qhov loj me ntawm cov khoom sib txawv, qib sib txawv ntawm viscosity thiab qhov ntxiv ntau yuav muaj qhov cuam tshuam zoo rau kev txhim kho qhov ua tau zoo ntawm cov tshuaj mortar hmoov qhuav. Tam sim no, ntau cov tshuaj mortar masonry thiab plastering muaj kev ua tau zoo tsis zoo, thiab cov dej slurry yuav sib cais tom qab ob peb feeb sawv.
Kev khaws dej yog ib qho tseem ceeb ntawm methyl cellulose ether, thiab nws kuj yog ib qho kev ua tau zoo uas ntau lub tuam txhab tsim cov tshuaj mortar qhuav hauv tsev, tshwj xeeb tshaj yog cov neeg nyob rau sab qab teb uas muaj qhov kub siab, tau them sai sai rau. Cov yam ntxwv cuam tshuam rau kev khaws dej ntawm cov tshuaj mortar qhuav suav nrog qhov ntau ntawm MC ntxiv, qhov viscosity ntawm MC, qhov zoo ntawm cov khoom me me thiab qhov kub ntawm qhov chaw siv.
Cov khoom ntawm cellulose ethers nyob ntawm hom, tus lej thiab kev faib tawm ntawm cov substituents. Kev faib tawm ntawm cellulose ethers kuj yog raws li hom substituents, qib ntawm etherification, solubility thiab cov khoom siv cuam tshuam. Raws li hom substituents ntawm cov saw molecular, nws tuaj yeem 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 tom qab hydroxyl pawg ntawm chav glucose ntawm cellulose ntuj yog hloov los ntawm methoxy. Cov qauv mis 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, cov no yog cov hom tseem ceeb siv dav thiab muag hauv khw.
Hais txog kev yaj, nws muaj peev xwm muab faib ua ionic thiab non-ionic. Cov dej-soluble non-ionic cellulose ethers feem ntau yog tsim los ntawm ob series ntawm alkyl ethers thiab hydroxyalkyl ethers. Ionic CMC feem ntau yog siv rau hauv cov tshuaj ntxuav hluavtaws, textile printing thiab dyeing, zaub mov thiab roj tshawb nrhiav. Non-ionic MC, HPMC, HEMC, thiab lwm yam feem ntau yog siv rau hauv cov ntaub ntawv tsim kho, latex coatings, tshuaj, tshuaj txhua hnub, thiab lwm yam. Siv ua thickener, dej tuav tus neeg sawv cev, stabilizer, dispersant thiab zaj duab xis tsim tus neeg sawv cev.
Kev khaws dej ntawm cellulose ether: Hauv kev tsim cov khoom siv hauv tsev, tshwj xeeb tshaj yog cov hmoov qhuav mortar, cellulose ether ua lub luag haujlwm tseem ceeb, tshwj xeeb tshaj yog hauv kev tsim cov mortar tshwj xeeb (hloov kho mortar), nws yog ib qho tseem ceeb thiab tseem ceeb. Lub luag haujlwm tseem ceeb ntawm cov dej-soluble cellulose ether hauv mortar feem ntau muaj peb yam:
1. Muaj peev xwm khaws dej tau zoo heev
2. Cov nyhuv rau kev sib xws ntawm cov mortar thiab thixotropy
3. Kev sib cuam tshuam nrog cov cement.
Qhov cuam tshuam ntawm kev khaws dej ntawm cellulose ether nyob ntawm qhov nqus dej ntawm cov txheej hauv paus, cov khoom sib xyaw ntawm cov mortar, qhov tuab ntawm cov txheej mortar, qhov xav tau dej ntawm cov mortar, thiab lub sijhawm teeb tsa ntawm cov khoom teeb tsa. Kev khaws dej ntawm cellulose ether nws tus kheej los ntawm qhov solubility thiab dehydration ntawm cellulose ether nws tus kheej. Raws li peb txhua tus paub, txawm hais tias cov saw hlau molecular cellulose muaj ntau tus lej ntawm cov pab pawg OH uas muaj dej ntau, nws tsis yaj hauv dej, vim tias cov qauv cellulose muaj qib siab ntawm crystallinity. Lub peev xwm hydration ntawm hydroxyl pawg ib leeg tsis txaus los npog cov hydrogen bonds muaj zog thiab van der Waals zog ntawm cov molecules. Yog li ntawd, nws tsuas yog swells tab sis tsis yaj hauv dej. Thaum ib qho substituent raug qhia rau hauv cov saw hlau molecular, tsis yog tsuas yog cov substituent rhuav tshem cov saw hlau hydrogen, tab sis kuj tseem muaj cov hydrogen bond interchain raug rhuav tshem vim yog qhov wedging ntawm cov substituent ntawm cov saw hlau sib ze. Qhov loj dua qhov substituent, qhov ntau dua qhov deb ntawm cov molecules. Qhov ntau dua qhov deb. Qhov cuam tshuam ntawm kev rhuav tshem cov hydrogen bonds ntau dua, cov cellulose ether ua rau dej-soluble tom qab cov cellulose lattice nthuav dav thiab cov tshuaj nkag mus, tsim cov tshuaj viscosity siab. Thaum qhov kub nce siab, qhov hydration ntawm cov polymer tsis muaj zog, thiab cov dej ntawm cov saw hlau raug tsav tawm. Thaum qhov cuam tshuam dehydration txaus, cov molecules pib sib sau ua ke, tsim cov qauv network peb-seem gel thiab tais tawm.
Lub sijhawm tshaj tawm: Lub Kaum Ob Hlis-06-2022