Cellulose ether yog ib qho polymer hluavtaws ua los ntawm cov cellulose ntuj ua cov khoom siv raw los ntawm kev hloov kho tshuaj. Cellulose ether yog ib qho derivative ntawm cellulose ntuj, cellulose ether ntau lawm thiab cov polymer hluavtaws yog txawv, nws cov khoom siv yooj yim tshaj plaws yog cellulose, cov 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 tus neeg sawv cev etherifying. Tab sis 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 tau raug rhuav tshem, thiab cov haujlwm ntawm hydroxyl pawg tau tso tawm rau hauv alkali cellulose nrog lub peev xwm ua haujlwm, thiab cellulose ether tau txais los ntawm kev cuam tshuam ntawm tus neeg sawv cev etherifying - OH pawg rau hauv - LOS YOG pawg.
Cov khoom ntawm cellulose ethers nyob ntawm hom, tus lej thiab kev faib tawm ntawm cov substituents. Kev faib tawm ntawm cellulose ether kuj yog raws li hom substituents, qib ntawm etherification, solubility thiab lwm yam kev siv tuaj yeem faib ua pawg. Raws li hom substituents ntawm cov saw molecular, nws tuaj yeem faib ua ib leeg ether thiab sib xyaw ether. MC feem ntau yog siv ua ib leeg ether, thaum HPmc yog sib xyaw ether. Methyl cellulose ether MC yog ib qho cellulose glucose unit ntuj ntawm hydroxyl yog methoxide hloov los ntawm cov qauv khoom mis [CO H7O2 (OH) 3-H (OCH3) H] X, hydroxypropyl methyl cellulose ether HPmc yog ib chav ntawm hydroxyl yog ib feem ntawm methoxide hloov, lwm ib feem ntawm hydroxypropyl hloov khoom, Cov qauv mis yog [C6H7O2 (OH) 3-MN (OCH3) M [OCH2CH (OH) CH3] N] X thiab hydroxyethyl methyl cellulose ether HEmc, uas yog siv dav thiab muag hauv khw.
Los ntawm qhov solubility muaj peev xwm muab faib ua hom ionic thiab hom tsis-ionic. Cov dej-soluble non-ionic cellulose ether feem ntau yog tsim los ntawm alkyl ether thiab hydroxyl alkyl ether ob series ntawm ntau yam. Ionic Cmc feem ntau yog siv rau hauv cov tshuaj ntxuav hluavtaws, textile, luam ntawv, khoom noj thiab roj av. 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. Ua thickening agent, water retention agent, stabilizer, dispersant, film forming agent.
Kev khaws cia dej ntawm cellulose ether
Hauv kev tsim cov ntaub ntawv siv hauv tsev, tshwj xeeb tshaj yog cov tshuaj khib qhuav, cellulose ether ua lub luag haujlwm tseem ceeb, tshwj xeeb tshaj yog hauv kev tsim cov tshuaj khib tshwj xeeb (hloov kho tshuaj khib), yog ib feem tseem ceeb.
Lub luag haujlwm tseem ceeb ntawm cov cellulose ether uas yaj tau hauv dej hauv cov mortar feem ntau muaj peb yam, ib qho yog lub peev xwm khaws dej zoo heev, qhov thib ob yog qhov cuam tshuam ntawm kev sib xws ntawm mortar thiab thixotropy, thiab qhov thib peb yog kev sib cuam tshuam nrog cement.
Kev khaws dej ntawm cellulose ether nyob ntawm lub hauv paus ntawm hydroscopicity, cov khoom sib xyaw ntawm mortar, qhov tuab ntawm cov mortar, qhov xav tau dej ntawm mortar, thiab lub sijhawm condensation ntawm cov khoom siv condensation. Kev khaws dej ntawm cellulose ether los ntawm qhov solubility thiab dehydration ntawm cellulose ether nws tus kheej. Nws paub zoo tias cellulose molecular chains, txawm hais tias lawv muaj ntau tus OH pawg hydrated heev, tsis yaj hauv dej vim lawv cov qauv crystalline heev. Lub peev xwm hydration ntawm hydroxyl pawg ib leeg tsis txaus los them rau cov hydrogen bonds intermolecular muaj zog thiab van der Waals zog. Thaum substituents raug qhia rau hauv molecular saw, tsis yog tsuas yog substituents rhuav tshem cov hydrogen saw, tab sis kuj tseem muaj cov hydrogen bonds interchain tawg vim yog wedging ntawm substituents ntawm cov saw sib ze. Qhov loj dua cov substituents yog, qhov ntau dua qhov deb ntawm cov molecules yog. Qhov ntau dua qhov kev puas tsuaj ntawm hydrogen bond effect, cellulose lattice nthuav dav, cov tshuaj rau hauv cellulose ether ua dej-soluble, tsim cov tshuaj viscosity siab. Thaum qhov kub nce siab, qhov dej ntawm cov polymer txo qis thiab cov dej ntawm cov saw hlau raug tsav tawm. Thaum qhov cuam tshuam ntawm kev ziab dej txaus, cov molecule pib sib sau ua ke thiab cov gel quav tawm hauv lub network peb-seem. Cov yam ntxwv cuam tshuam rau kev khaws dej ntawm cov mortar suav nrog cellulose ether viscosity, dosage, particle fineness thiab kev pabcuam kub.
Qhov ntau dua qhov viscosity ntawm cellulose ether, qhov zoo dua qhov kev ua tau zoo ntawm kev khaws dej, qhov viscosity ntawm cov tshuaj polymer. Qhov hnyav molecular (degree ntawm polymerization) ntawm polymer kuj tseem txiav txim siab los ntawm qhov ntev thiab morphology ntawm cov qauv molecular ntawm cov saw, thiab kev faib tawm ntawm tus lej ntawm cov substituents ncaj qha cuam tshuam rau qhov ntau ntawm viscosity. [eta] = Km alpha
Intrinsic viscosity ntawm cov tshuaj polymer
Qhov hnyav molecular ntawm M polymer
α polymer yam ntxwv tas mus li
K viscosity kua coefficient
Qhov viscosity ntawm cov tshuaj polymer nyob ntawm qhov hnyav molecular ntawm cov polymer. Qhov viscosity thiab concentration ntawm cov tshuaj cellulose ether muaj feem cuam tshuam rau ntau yam kev siv. Yog li ntawd, txhua cellulose ether muaj ntau yam viscosity specifications sib txawv, kev tswj viscosity kuj tseem yog los ntawm kev puas tsuaj ntawm alkali cellulose, uas yog, kev tawg ntawm cellulose molecular saw kom ua tiav.
Rau qhov loj ntawm cov khoom me me, cov khoom me me dua, qhov zoo dua qhov khaws cia dej. Cov khoom loj ntawm cellulose ether sib cuag 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 rau hauv, qee zaum ntev lub sijhawm do tsis tuaj yeem sib npaug zos yaj, tsim cov kua flocculent av nkos lossis agglomerate. Qhov solubility ntawm cellulose ether yog ib qho ntawm cov yam tseem ceeb los xaiv cellulose ether.
Thickening thiab thixotropy ntawm cellulose ether
Qhov thib ob ntawm cellulose ether - thickening nyob ntawm: cellulose ether polymerization degree, cov tshuaj concentration, shear rate, kub thiab lwm yam mob. Lub zog gelation ntawm cov tshuaj yog tshwj xeeb rau alkyl cellulose thiab nws cov derivatives hloov kho. Cov yam ntxwv gelation muaj feem cuam tshuam nrog qib ntawm kev hloov pauv, cov tshuaj concentration thiab cov additives. Rau hydroxyl alkyl modified derivatives, gel cov khoom kuj muaj feem cuam tshuam nrog qib ntawm hydroxyl alkyl hloov kho. Rau cov tshuaj concentration ntawm qis viscosity MC thiab HPmc tuaj yeem npaj 10% -15% concentration tshuaj, nruab nrab viscosity MC thiab HPmc tuaj yeem npaj 5% -10% tshuaj thiab siab viscosity MC thiab HPmc tsuas yog tuaj yeem npaj 2% -3% tshuaj, thiab feem ntau viscosity ntawm cellulose ether kuj tau qib los ntawm 1% -2% tshuaj. Qhov hnyav molecular siab cellulose ether thickener ua haujlwm tau zoo, tib qhov concentration ntawm cov tshuaj, cov polymers hnyav molecular sib txawv muaj viscosity sib txawv, viscosity thiab molecular hnyav tuaj yeem qhia raws li hauv qab no, [η] = 2.92 × 10-2 (DPn) 0.905, DPn yog qhov nruab nrab polymerization degree ntawm siab. Qhov hnyav molecular qis cellulose ether ntxiv ntau dua kom ua tiav lub hom phiaj viscosity. Nws viscosity tsawg dua nyob ntawm shear rate, viscosity siab kom ua tiav lub hom phiaj viscosity, qhov ntau uas xav tau ntxiv tsawg dua, viscosity nyob ntawm qhov thickening efficiency. Yog li ntawd, kom ua tiav qee qhov sib xws, ib qho ntau ntawm cellulose ether (concentration ntawm cov tshuaj) thiab viscosity ntawm cov tshuaj yuav tsum tau lees paub. Qhov kub ntawm cov tshuaj gelation txo qis linearly nrog qhov nce ntawm qhov concentration ntawm cov tshuaj, thiab gelation tshwm sim ntawm chav tsev kub tom qab mus txog qee qhov concentration. HPmc muaj qhov concentration gelation siab ntawm chav tsev kub.
Qhov sib xws kuj tseem tuaj yeem hloov kho los ntawm kev xaiv qhov loj me ntawm cov khoom me me thiab cellulose ethers nrog ntau qib kev hloov kho. Qhov kev hloov kho hu ua yog kev qhia txog hydroxyl alkyl pawg hauv qee qib ntawm kev hloov pauv ntawm cov qauv pob txha ntawm MC. Los ntawm kev hloov pauv cov nqi hloov pauv ntawm ob qho kev hloov pauv, uas yog, DS thiab MS cov nqi hloov pauv ntawm methoxy thiab hydroxyl pawg. Ntau yam khoom ntawm cellulose ether yog qhov yuav tsum tau los ntawm kev hloov pauv cov nqi hloov pauv ntawm ob hom kev hloov pauv.
kev sib raug zoo ntawm kev sib xws thiab kev hloov kho. Hauv Daim Duab 5, kev ntxiv cov cellulose ether cuam tshuam rau kev siv dej ntawm cov mortar thiab hloov pauv qhov sib piv ntawm dej-binder ntawm dej thiab cement, uas yog qhov ua rau tuab. Qhov ntau dua qhov koob tshuaj, qhov ntau dua kev siv dej.
Cov cellulose ethers siv rau hauv cov ntaub ntawv ua vaj tse hmoov yuav tsum yaj sai sai hauv dej txias thiab muab lub kaw lus nrog qhov sib xws. Yog tias qhov nrawm ntawm kev txiav tseem yog flocculent thiab colloidal nws yog cov khoom tsis zoo lossis tsis zoo.
Kuj tseem muaj kev sib raug zoo ntawm cov cement slurry sib xws thiab cov koob tshuaj ntawm cellulose ether, cellulose ether tuaj yeem ua rau kom cov viscosity ntawm mortar ntau ntxiv, qhov ntau dua ntawm cov koob tshuaj, qhov pom tseeb dua.
Cov kua dej cellulose ether uas muaj viscosity siab muaj thixotropy siab, uas yog ib qho ntawm cov yam ntxwv ntawm cellulose ether. Cov kua dej ntawm Mc hom polymers feem ntau muaj pseudoplastic, tsis yog thixotropic fluidity qis dua lawv qhov kub gel, tab sis Newtonian ntws cov khoom ntawm qhov qis shear. Pseudoplasticity nce nrog qhov nce ntawm qhov hnyav molecular lossis concentration ntawm cellulose ether thiab tsis yog nyob ntawm hom substituent thiab degree. Yog li ntawd, cellulose ethers ntawm tib qib viscosity, txawm tias MC, HPmc lossis HEmc, ib txwm qhia tib yam rheological khoom ntev li ntev tau qhov concentration thiab kub tseem nyob ruaj khov. Thaum qhov kub nce, cov qauv gel yog tsim thiab cov dej ntws thixotropic siab tshwm sim. Cellulose ethers nrog cov concentration siab thiab viscosity qis qhia thixotropy txawm tias qis dua qhov kub gel. Cov khoom no yog qhov zoo rau kev tsim kho ntawm lub tsev mortar los kho nws cov dej ntws thiab ntws dai khoom. Nws yuav tsum tau piav qhia ntawm no tias qhov siab dua qhov viscosity ntawm cellulose ether, qhov zoo dua qhov kev khaws cia dej, tab sis qhov siab dua qhov viscosity, qhov siab dua qhov hnyav molecular ntawm cellulose ether, qhov sib xws txo qis ntawm nws cov solubility, uas muaj qhov cuam tshuam tsis zoo rau qhov concentration ntawm mortar thiab kev ua haujlwm ntawm kev tsim kho. Qhov siab dua qhov viscosity, qhov pom tseeb ntau dua qhov thickening nyhuv ntawm mortar, tab sis nws tsis yog kev sib raug zoo tag nrho. Qee qhov viscosity qis, tab sis hloov kho cellulose ether hauv kev txhim kho lub zog ntawm cov mortar ntub muaj kev ua tau zoo dua, nrog rau kev nce ntawm viscosity, cellulose ether dej khaws cia tau zoo dua.
Lub sijhawm tshaj tawm: Lub Peb Hlis-30-2022