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.
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. Nws yog ib qho khoom tau los ntawm kev hloov ib feem ntawm pawg hydroxyl ntawm chav tsev nrog methoxy pawg thiab lwm qhov nrog ib pawg hydroxypropyl. Cov qauv qauv yog [C6H7O2(OH) 3-mn(OCH3)m[OCH2CH(OH)CH3]n] x Hydroxyethyl methyl cellulose ether HEMC, cov no yog cov hom tseem ceeb uas tau siv thiab muag hauv khw.
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 mortar qhuav, 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. Cov yam ntxwv cuam tshuam rau cov dej tuav ntawm mortar muaj xws li viscosity ntawm cellulose ether, tus nqi ntxiv, qhov zoo ntawm cov khoom thiab qhov kub thiab txias.
Qhov siab dua qhov viscosity ntawm cellulose ether, qhov zoo dua cov dej tuav kev ua haujlwm, thiab siab dua qhov viscosity ntawm cov tshuaj polymer. Nyob ntawm qhov hnyav molecular (polymerization degree) ntawm cov polymer, nws kuj tseem txiav txim siab los ntawm cov saw ntev ntawm cov qauv molecular thiab cov duab ntawm cov saw, thiab kev faib tawm ntawm hom thiab qhov ntau ntawm cov khoom siv kuj cuam tshuam ncaj qha rau nws cov viscosity ntau yam. [η]=Kmα
[η] Intrinsic viscosity ntawm polymer kua
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 tov muaj feem xyuam rau daim ntawv thov nyob rau hauv ntau yam teb. Yog li ntawd, txhua tus cellulose ether muaj ntau yam sib txawv viscosity specifications, thiab kev hloov ntawm viscosity yog tsuas yog pom tau hais tias los ntawm degradation ntawm alkali cellulose, uas yog, tawg ntawm cellulose molecular chains.
Qhov ntau dua ntawm cov cellulose ether ntxiv rau hauv mortar, qhov dej tuav tau zoo dua, thiab qhov viscosity siab dua, qhov dej tuav tau zoo dua.
Rau particle loj, qhov finer particle, qhov zoo dua cov dej tuav. Saib daim duab 3. Tom qab cov khoom loj ntawm cellulose ether sib cuag nrog dej, qhov saum npoo tam sim ntawd dissolves thiab tsim cov gel los qhwv cov khoom kom tiv thaiv cov dej molecules los ntawm kev nkag mus ntxiv. Tsawg tshaj li qhov sib txawv dispersion dissolves, tsim cov huab flocculent tov los yog agglomerates. Nws cuam tshuam rau cov dej tuav ntawm cellulose ether, thiab solubility yog ib qho tseem ceeb ntawm kev xaiv cellulose ether.
Thickening thiab Thixotropy ntawm Cellulose Ether
Qhov thib ob ua haujlwm ntawm cellulose ether - thickening, nyob ntawm: qib ntawm polymerization ntawm cellulose ether, kua concentration, shear npaum li cas, kub thiab lwm yam kev 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 qis viscosity MC thiab HPMC, 10% -15% tov tuaj yeem npaj, nruab nrab viscosity MC thiab HPMC tuaj yeem npaj 5%-10% tov, thiab 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 nrog 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.
Kev sib raug zoo kuj tuaj yeem hloov kho los ntawm kev xaiv qhov loj me thiab xaiv cellulose ethers nrog ntau qib kev hloov kho. Qhov kev hloov pauv yog los qhia txog qee qhov kev hloov pauv ntawm pawg hydroxyalkyl ntawm cov pob txha pob txha ntawm MC. Los ntawm kev hloov pauv tus txheeb ze qhov txiaj ntsig ntawm ob tus neeg hloov pauv, uas yog, DS thiab MS txheeb ze hloov pauv qhov txiaj ntsig ntawm pawg methoxy thiab hydroxyalkyl uas peb feem ntau hais. Ntau yam kev ua tau zoo ntawm cellulose ether tuaj yeem tau txais los ntawm kev hloov pauv cov txiaj ntsig sib txawv ntawm ob qhov hloov pauv.
Cellulose ethers siv hauv cov khoom siv hauv tsev yuav tsum yaj sai sai hauv dej txias thiab muab qhov tsim nyog rau lub cev. Yog tias muab qee qhov kev txiav tawm, nws tseem dhau los ua flocculent thiab colloidal block, uas yog cov khoom lag luam tsis zoo lossis cov khoom tsis zoo.
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. Aqueous kev daws teeb meem ntawm MC polymers feem ntau muaj pseudoplastic thiab non-thixotropic fluidity hauv qab lawv cov gel kub, tab sis Newtonian ndlwg zog ntawm qis shear tus nqi. Pseudoplasticity nce nrog qhov hnyav molecular lossis concentration ntawm cellulose ether, tsis hais hom kev hloov pauv thiab qib ntawm kev hloov pauv. Yog li ntawd, cellulose ethers ntawm tib qib viscosity, tsis hais MC, HPMC, HEMC, yuav ib txwm qhia tib yam rheological zog ntev npaum li qhov concentration thiab kub nyob twj ywm. Cov txheej txheem gels yog tsim thaum qhov kub thiab txias, thiab thixotropic ntws heev. High concentration thiab tsawg viscosity cellulose ethers qhia thixotropy txawm nyob rau hauv lub gel kub. Cov cuab yeej no muaj txiaj ntsig zoo rau kev hloov kho ntawm qib thiab sagging hauv kev tsim kho ntawm lub tsev mortar. 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, thiab qhov sib thooj hauv nws cov solubility, uas muaj kev cuam tshuam tsis zoo. ntawm mortar concentration thiab kev tsim kho. Qhov siab dua qhov viscosity, qhov pom tseeb dua cov nyhuv thickening ntawm cov tshuaj khib, tab sis nws tsis yog proportional kiag li. Qee qhov nruab nrab thiab qis viscosity, tab sis hloov kho cellulose ether muaj kev ua tau zoo dua hauv kev txhim kho lub zog ntawm cov mortar ntub dej. Nrog rau qhov nce ntawm viscosity, cov dej tuav ntawm cellulose ether txhim kho
Post lub sij hawm: Nov-22-2022