Cellulose ether yog ib qho hluavtaws polymer ua los ntawm ntuj cellulose ua raw khoom los ntawm kev hloov tshuaj. Cellulose ether yog derivative ntawm natural cellulose, cellulose ether ntau lawm thiab hluavtaws polymer yog txawv, nws cov khoom siv yooj yim tshaj plaws yog cellulose, natural polymer compounds. Vim qhov tshwj xeeb ntawm cov qauv cellulose, cellulose nws tus kheej tsis muaj peev xwm ua rau muaj kev cuam tshuam nrog etherifying tus neeg sawv cev. Tab sis tom qab kev kho mob ntawm tus neeg sawv cev o, lub zog hydrogen bonds ntawm molecular chains thiab chains raug rhuav tshem, thiab cov kev ua ntawm hydroxyl pawg tau tso tawm rau hauv alkali cellulose nrog lub peev xwm tshuaj tiv thaiv, thiab cellulose ether tau txais los ntawm cov tshuaj tiv thaiv ntawm etherifying agent - OH pawg rau hauv. — LOSSIS pab pawg.
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 ether kuj yog nyob ntawm hom kev hloov pauv, qib ntawm etherification, solubility thiab lwm yam kev thov tuaj yeem raug cais tawm. Raws li hom kev hloov pauv ntawm cov saw hlau molecular, nws tuaj yeem muab faib ua ib leeg ether thiab sib xyaw ether. MC feem ntau yog siv los ua ib qho ether, thaum HPmc yog ib qho ether sib xyaw. Methyl cellulose ether MC yog lub ntuj cellulose qabzib chav tsev ntawm hydroxyl yog methoxide hloov los ntawm cov khoom qauv formula [CO H7O2 (OH) 3-H (OCH3) H] X, hydroxypropyl methyl cellulose ether HPmc yog ib chav nyob ntawm hydroxyl yog ib feem. ntawm methoxide hloov, lwm qhov ntawm hydroxypropyl hloov khoom, Cov qauv qauv yog [C6H7O2 (OH) 3-MN (OCH3) M [OCH2CH (OH) CH3] N] X thiab hydroxyethyl methyl cellulose ether HEmc, uas yog dav siv thiab muag hauv khw.
Los ntawm solubility tuaj yeem muab faib ua hom ionic thiab hom tsis-ionic. Dej-soluble non-ionic cellulose ether yog tsim los ntawm alkyl ether thiab hydroxyl alkyl ether ob series ntawm ntau yam. Ionic Cmc feem ntau yog siv rau hauv cov khoom siv hluavtaws, textile, luam ntawv, khoom noj khoom haus thiab kev siv roj av. Non-ionic MC, HPmc, HEmc thiab lwm yam feem ntau siv hauv cov khoom siv hauv tsev, latex coatings, tshuaj, chemistry txhua hnub thiab lwm yam. Raws li thickening tus neeg saib xyuas, dej tuav tus neeg saib xyuas, stabilizer, dispersant, film forming agent.
Cellulose ether tuav dej
Hauv kev tsim cov khoom siv hauv tsev, tshwj xeeb tshaj yog qhuav sib xyaw mortar, cellulose ether plays lub luag haujlwm hloov tsis tau, tshwj xeeb tshaj yog nyob rau hauv kev tsim cov tshuaj khib tshwj xeeb (hloov mortar), yog ib feem tseem ceeb.
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, qhov thib ob yog kev cuam tshuam ntawm mortar sib xws thiab thixotropy, thiab qhov thib peb yog kev sib cuam tshuam nrog cov cement.
Cellulose ether dej tuav, nyob ntawm lub hauv paus ntawm hydroscopicity, muaj pes tsawg leeg ntawm mortar, mortar txheej thickness, mortar dej xav tau, condensation khoom condensation lub sij hawm. Cov dej tuav ntawm cellulose ether los ntawm solubility thiab lub cev qhuav dej ntawm cellulose ether nws tus kheej. Nws yog qhov paub zoo tias cov saw cellulose molecular, txawm hais tias lawv muaj ntau cov hydrated OH pawg, yog insoluble hauv dej vim lawv cov qauv crystalline heev. Lub peev xwm hydration ntawm hydroxyl pab pawg ib leeg tsis txaus los them rau cov muaj zog intermolecular hydrogen bonds thiab van der Waals rog. Thaum cov khoom hloov pauv tau nkag mus rau hauv cov saw hlau molecular, tsis yog cov khoom hloov pauv tsuas yog rhuav tshem cov saw hlau hydrogen, tab sis kuj tseem muaj cov interchain hydrogen bonds tawg vim qhov sib txuas ntawm cov khoom sib txuas ntawm cov saw hlau uas nyob ib sab. Qhov loj dua qhov hloov pauv, qhov kev ncua deb ntawm molecules ntau dua. Qhov ntau dua qhov kev puas tsuaj ntawm hydrogen bond effect, cellulose lattice expansion, cov tshuaj rau hauv cellulose ether ua dej-soluble, tsim cov viscosity siab. Raws li qhov kub nce siab, cov dej ntawm cov polymer txo qis thiab cov dej ntawm cov saw hlau raug tsav tawm. Thaum lub cev qhuav dej txaus, cov molecules pib sib sau ua ke thiab cov gel folds tawm hauv peb-dimensional network. Cov yam ntxwv cuam tshuam rau cov dej khaws cia ntawm mortar suav nrog cellulose ether viscosity, ntau npaum li cas, particle fineness thiab kev pabcuam kub.
Qhov ntau dua qhov viscosity ntawm cellulose ether, qhov zoo dua cov dej tuav kev ua haujlwm, viscosity ntawm cov tshuaj polymer. Qhov hnyav molecular (degree ntawm polymerization) ntawm polymer kuj yog txiav txim siab los ntawm qhov ntev thiab morphology ntawm cov qauv molecular ntawm cov saw, thiab kev faib cov naj npawb ntawm cov khoom hloov ncaj qha cuam tshuam rau viscosity ntau yam. [eta] = Km alpha
Intrinsic viscosity ntawm cov tshuaj polymer
M polymer molecular hnyav
α polymer yam ntxwv tsis tu ncua
K viscosity kua coefficient
Lub viscosity ntawm cov tshuaj polymer yog nyob ntawm qhov hnyav molecular ntawm cov polymer. Lub viscosity thiab concentration ntawm cellulose ether daws muaj feem xyuam rau ntau yam kev siv. Yog li ntawd, txhua cellulose ether muaj ntau yam sib txawv viscosity specifications, viscosity kev cai kuj tseem yog los ntawm degradation ntawm alkali cellulose, uas yog lub pob txha ntawm cellulose molecular saw mus cuag.
Rau particle loj, qhov finer particle, qhov zoo dua cov dej tuav. Cov khoom loj ntawm cellulose ether tiv tauj nrog dej, qhov chaw tam sim ntawd yaj thiab tsim cov gel los qhwv cov khoom kom tiv thaiv cov dej molecules los ntawm kev txuas ntxiv mus, qee zaum ntev stirring tsis tuaj yeem sib npaug dispersed yaj, tsim cov av nkos flocculent tov los yog agglomerate. Lub solubility ntawm cellulose ether yog ib qho ntawm cov yam ntxwv los xaiv cellulose ether.
Thickening thiab thixotropy ntawm cellulose ether
Qhov thib ob nyhuv ntawm cellulose ether - thickening nyob ntawm: cellulose ether polymerization degree, kua concentration, shear npaum li cas, kub thiab lwm yam mob. Cov cuab yeej gelation ntawm kev daws yog tshwj xeeb rau alkyl cellulose thiab nws cov derivatives hloov. Cov yam ntxwv gelation muaj feem xyuam nrog kev hloov pauv, kev daws teeb meem thiab cov khoom ntxiv. Rau hydroxyl alkyl hloov derivatives, gel zog kuj muaj feem xyuam rau qib ntawm hydroxyl alkyl hloov kho. Rau cov tshuaj concentration ntawm tsawg viscosity MC thiab HPmc tuaj yeem npaj 10% -15% concentration tov, nruab nrab viscosity MC thiab HPmc tuaj yeem npaj 5%-10% tov thiab siab viscosity MC thiab HPmc tsuas yog npaj tau 2% -3% cov tshuaj, thiab feem ntau cov viscosity ntawm cellulose ether kuj yog graded los ntawm 1% -2% tov. Qhov hnyav molecular cellulose ether thickener efficiency, tib lub concentration ntawm kev daws, sib txawv molecular hnyav polymers muaj txawv viscosity, viscosity thiab molecular hnyav yuav qhia tau raws li nram no, [η] = 2.92 × 10-2 (DPn) 0.905, DPn yog qhov nruab nrab polymerization degree ntawm siab. Tsawg molecular hnyav cellulose ether ntxiv kom ua tiav lub hom phiaj viscosity. Nws cov viscosity tsawg dua nyob ntawm tus nqi shear, siab viscosity kom ua tiav lub hom phiaj viscosity, tus nqi yuav tsum tau ntxiv tsawg dua, 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. Lub gelation kub ntawm cov tshuaj txo qis linearly nrog qhov nce ntawm cov concentration ntawm cov tshuaj, thiab gelation tshwm sim nyob rau hauv chav tsev kub tom qab ncav cuag ib tug tej yam concentration. HPmc muaj gelation concentration ntawm chav tsev kub.
Qhov sib xws kuj tuaj yeem hloov kho los ntawm kev xaiv qhov loj me thiab cellulose ethers nrog ntau qib kev hloov kho. Qhov kev hloov pauv yog kev qhia txog cov pab pawg hydroxyl alkyl hauv qee qhov kev hloov pauv ntawm cov pob txha pob txha ntawm MC. Los ntawm kev hloov pauv cov txiaj ntsig sib txawv ntawm ob tus neeg hloov pauv, uas yog, DS thiab MS txheeb ze hloov pauv qhov txiaj ntsig ntawm methoxy thiab hydroxyl pawg. Ntau yam khoom ntawm cellulose ether yuav tsum tau los ntawm kev hloov pauv cov txiaj ntsig sib txawv ntawm ob hom kev hloov pauv.
kev sib raug zoo ntawm kev sib xws thiab kev hloov kho. Nyob rau hauv daim duab 5, qhov sib ntxiv ntawm cellulose ether cuam tshuam cov dej siv ntawm mortar thiab hloov cov dej-binder ratio ntawm dej thiab cement, uas yog cov thickening nyhuv. Qhov ntau npaum li cas, kev siv dej ntau dua.
Cellulose ethers siv hauv cov khoom siv hauv tsev yuav tsum yaj sai sai hauv dej txias thiab muab cov kab ke kom zoo sib xws. Yog hais tias ib tug muab shear npaum li cas tseem flocculent thiab colloidal nws yog ib tug substandard los yog tsis zoo cov khoom.
Kuj tseem muaj kev sib raug zoo ntawm cov cement slurry zoo ib yam thiab ntau npaum ntawm cellulose ether, cellulose ether tuaj yeem ua rau kom cov viscosity ntawm mortar ntau dua, qhov ntau npaum li cas, qhov pom tseeb ntawm cov nyhuv.
Cellulose ether aqueous tov nrog siab viscosity muaj siab thixotropy, uas yog ib qho ntawm cov yam ntxwv ntawm cellulose ether. Aqueous daws ntawm Mc hom polymers feem ntau muaj pseudoplastic, uas tsis yog-thixotropic fluidity hauv qab lawv cov gel kub, tab sis Newtonian ndlwg zog ntawm qis shear tus nqi. Pseudoplasticity nce nrog qhov nce ntawm qhov hnyav ntawm molecular lossis concentration ntawm cellulose ether thiab tsis muaj kev hloov pauv ntawm hom thiab qib. Yog li, cellulose ethers ntawm tib qib viscosity, txawm tias MC, HPmc lossis HEmc, ib txwm qhia tib lub zog rheological ntev npaum li qhov concentration thiab kub nyob twj ywm. Thaum qhov kub nce, cov txheej txheem gel yog tsim thiab siab thixotropic ntws tshwm sim. Cellulose ethers nrog siab concentration thiab tsawg viscosity pom thixotropy txawm tias qis dua qhov kub ntawm gel. Cov cuab yeej no muaj txiaj ntsig zoo rau kev tsim vaj tsev mortar los kho nws cov dej ntws thiab ntws cov khoom dai. Nws yuav tsum tau piav qhia ntawm no tias qhov siab dua qhov viscosity ntawm cellulose ether, qhov dej tuav tau zoo dua, tab sis qhov siab dua qhov viscosity, qhov siab dua qhov txheeb ze molecular hnyav ntawm cellulose ether, qhov txo qis ntawm nws cov solubility, uas muaj kev cuam tshuam tsis zoo. lub mortar concentration thiab kev tsim kho. Qhov siab dua qhov viscosity, qhov pom tseeb dua cov nyhuv ntawm cov tshuaj khib nyiab, tab sis nws tsis yog kev sib raug zoo ntawm kev sib raug zoo. Qee qhov qis viscosity, tab sis hloov kho cellulose ether hauv kev txhim kho lub zog ntawm cov mortar ntub dej muaj kev ua tau zoo dua, nrog rau qhov nce ntawm viscosity, cellulose ether dej tuav tau zoo tuaj.
Lub sij hawm xa tuaj: Mar-30-2022