Cov qauv ib txwm muaj ntawm obcov cellulose etherstau muab rau hauv Cov Duab 1.1 thiab 1.2. Txhua lub β-D-dehydrated txiv hmab ntawm ib lub molecule cellulose
Chav qab zib (chav rov ua dua ntawm cellulose) raug hloov nrog ib pawg ether txhua tus ntawm C (2), C (3) thiab C (6) txoj haujlwm, piv txwv li txog li peb
ib pawg ether. Vim muaj cov pab pawg hydroxyl, cellulose macromolecules muaj cov hydrogen bonds intramolecular thiab intermolecular, uas nyuaj rau yaj hauv dej.
Thiab nws nyuaj rau yaj hauv yuav luag txhua cov kuab tshuaj organic. Txawm li cas los xij, tom qab etherification ntawm cellulose, ether pawg tau qhia rau hauv cov saw molecular,
Ua li no, cov hydrogen bonds hauv thiab ntawm cov molecules ntawm cellulose raug rhuav tshem, thiab nws cov hydrophilicity kuj tau txhim kho, yog li nws cov solubility tuaj yeem txhim kho.
zoo heev. Ntawm lawv, Daim Duab 1.1 yog cov qauv dav dav ntawm ob lub anhydroglucose units ntawm cellulose ether molecular saw, R1-R6 = H
los yog cov organic substituents. 1.2 yog ib daim ntawm carboxymethyl hydroxyethyl cellulose molecular saw, qib ntawm kev hloov pauv ntawm carboxymethyl yog 0.5,4
Qhov degree hloov ntawm hydroxyethyl yog 2.0, thiab qhov degree hloov molar yog 3.0.
Rau txhua qhov hloov pauv ntawm cellulose, tag nrho cov nyiaj ntawm nws cov etherification tuaj yeem qhia tau tias yog qib ntawm kev hloov pauv (DS). ua los ntawm cov fibers
Nws tuaj yeem pom los ntawm cov qauv ntawm lub molecule tseem ceeb uas qib ntawm kev hloov pauv yog txij li 0-3. Ntawd yog, txhua lub nplhaib anhydroglucose ntawm cellulose
, tus lej nruab nrab ntawm cov pab pawg hydroxyl hloov los ntawm cov pab pawg etherifying ntawm tus neeg sawv cev etherifying. Vim yog pawg hydroxyalkyl ntawm cellulose, nws cov kev hloov pauv
Qhov kev sib xyaw ua ke yuav tsum tau rov pib dua los ntawm pawg hydroxyl dawb tshiab. Yog li ntawd, qib ntawm kev hloov pauv ntawm hom cellulose ether no tuaj yeem qhia tau hauv moles.
degree of substitution (MS). Qhov hu ua molar degree of substitution qhia txog qhov ntau ntawm cov etherifying agent ntxiv rau txhua chav anhydroglucose ntawm cellulose
Qhov nruab nrab ntawm cov reactants.
1 Cov qauv dav dav ntawm chav ntsuas qabzib
2 Cov ntu ntawm cov cellulose ether molecular chains
1.2.2 Kev faib tawm ntawm cellulose ethers
Txawm hais tias cellulose ethers yog cov ethers ib leeg lossis cov ethers sib xyaw, lawv cov khoom sib txawv me ntsis. Cellulose macromolecules
Yog tias pawg hydroxyl ntawm lub nplhaib chav tsev raug hloov los ntawm pawg hydrophilic, cov khoom tuaj yeem muaj qib qis dua ntawm kev hloov pauv nyob rau hauv qhov xwm txheej ntawm qib qis dua ntawm kev hloov pauv.
Nws muaj qee qhov dej solubility; yog tias nws raug hloov los ntawm pawg hydrophobic, cov khoom muaj qee qib ntawm kev hloov pauv tsuas yog thaum qib ntawm kev hloov pauv yog nruab nrab.
Cov khoom uas yaj tau hauv dej, cov khoom uas tsis hloov pauv ntau cellulose etherification tsuas yog o tuaj yeem hauv dej, lossis yaj hauv cov kua alkali uas tsis muaj zog.
nruab nrab.
Raws li cov hom substituents, cellulose ethers tuaj yeem muab faib ua peb pawg: alkyl pawg, xws li methyl cellulose, ethyl cellulose;
Hydroxyalkyls, xws li hydroxyethyl cellulose, hydroxypropyl cellulose; lwm yam, xws li carboxymethyl cellulose, thiab lwm yam. Yog tias qhov ionization
Kev faib tawm, cellulose ethers tuaj yeem muab faib ua: ionic, xws li carboxymethyl cellulose; non-ionic, xws li hydroxyethyl cellulose; sib xyaw
hom, xws li hydroxyethyl carboxymethyl cellulose. Raws li kev faib tawm ntawm solubility, cellulose tuaj yeem muab faib ua: dej-soluble, xws li carboxymethyl cellulose,
Hydroxyethyl cellulose; dej-insoluble, xws li methyl cellulose, thiab lwm yam.
1.2.3 Cov khoom thiab daim ntawv thov ntawm cellulose ethers
Cellulose ether yog ib hom khoom tom qab cellulose etherification hloov kho, thiab cellulose ether muaj ntau yam khoom tseem ceeb heev. zoo li
Nws muaj cov khoom zoo ua zaj duab xis; ua ib qho tshuaj nplaum luam ntawv, nws muaj cov dej zoo solubility, cov khoom tuab, khaws dej thiab ruaj khov;
5
Cov ether yooj yim tsis muaj ntxhiab, tsis muaj tshuaj lom, thiab muaj kev sib raug zoo ntawm biocompatibility. Ntawm lawv, carboxymethyl cellulose (CMC) muaj "kev lag luam monosodium glutamate"
lub npe menyuam yaus.
1.2.3.1 Kev tsim zaj duab xis
Qhov degree ntawm etherification ntawm cellulose ether muaj kev cuam tshuam loj heev rau nws cov khoom tsim zaj duab xis xws li lub peev xwm tsim zaj duab xis thiab lub zog sib txuas.
Vim nws lub zog zoo thiab kev sib raug zoo nrog ntau yam resins, nws tuaj yeem siv rau hauv cov yas zaj duab xis, cov nplaum thiab lwm yam ntaub ntawv.
kev npaj khoom siv.
1.2.3.2 Kev yaj tau
Vim muaj ntau pawg hydroxyl ntawm lub nplhaib ntawm cov pa oxygen-muaj glucose unit, cellulose ethers muaj dej solubility zoo dua. thiab
Nyob ntawm seb tus cellulose ether substituent thiab qib ntawm kev hloov pauv, kuj muaj kev xaiv sib txawv rau cov organic solvents.
1.2.3.3 Ua kom tuab
Cellulose ether yog yaj rau hauv cov kua dej hauv daim ntawv ntawm colloid, qhov twg qib ntawm polymerization ntawm cellulose ether txiav txim siab qhov cellulose
Qhov viscosity ntawm cov kua ether. Tsis zoo li Newtonian kua, qhov viscosity ntawm cellulose ether kua hloov pauv nrog lub zog shear, thiab
Vim yog cov qauv no ntawm cov macromolecules, qhov viscosity ntawm cov tshuaj yuav nce sai nrog rau qhov nce ntawm cov khoom khov ntawm cellulose ether, txawm li cas los xij qhov viscosity ntawm cov tshuaj
Qhov viscosity kuj txo qis sai sai nrog rau qhov kub thiab txias nce ntxiv [33].
1.2.3.4 Kev puas tsuaj yooj yim
Cov kua cellulose ether uas yaj hauv dej rau ib lub sijhawm yuav loj hlob cov kab mob, yog li ntawd tsim cov kab mob enzyme thiab rhuav tshem cov theem cellulose ether.
Cov khoom sib txuas ntawm cov piam thaj uas tsis tau hloov pauv sib txuas, yog li ntawd txo qhov hnyav ntawm cov macromolecule. Yog li ntawd, cellulose ethers
Kev khaws cia cov kua dej yuav tsum tau ntxiv qee yam tshuaj preservatives.
Ntxiv rau, cellulose ethers muaj ntau lwm yam khoom tshwj xeeb xws li kev ua haujlwm ntawm qhov chaw, kev ua haujlwm ionic, kev ruaj khov ua npuas ncauj thiab cov khoom ntxiv.
gel ua haujlwm. Vim yog cov khoom no, cellulose ethers yog siv rau hauv textiles, papermaking, synthetic detergents, cosmetics, food, tshuaj,
Nws yog dav siv nyob rau hauv ntau lub teb.
1.3 Kev Taw Qhia Txog Cov Khoom Siv Raw Ntawm Cov Nroj Tsuag
Los ntawm kev txheeb xyuas ntawm 1.2 cellulose ether, nws tuaj yeem pom tias cov khoom siv raw rau kev npaj cellulose ether feem ntau yog paj rwb cellulose, thiab ib qho ntawm cov ntsiab lus ntawm cov ncauj lus no
Nws yog siv cellulose rho tawm los ntawm cov khoom siv raw ntawm cov nroj tsuag los hloov paj rwb cellulose los npaj cellulose ether. Cov hauv qab no yog kev qhia luv luv rau cov nroj tsuag
khoom siv.
Raws li cov peev txheej xws li roj, thee thiab roj av tab tom poob qis, kev tsim cov khoom sib txawv raws li lawv, xws li cov xov paj hluavtaws thiab cov yeeb yaj kiab fiber, kuj tseem yuav raug txwv ntau ntxiv. Nrog rau kev txhim kho tas mus li ntawm lub zej zog thiab cov tebchaws thoob ntiaj teb (tshwj xeeb tshaj yog
Nws yog ib lub teb chaws uas tsim kho) uas ua tib zoo saib xyuas qhov teeb meem ntawm kev ua qias tuaj ib puag ncig. Cov cellulose ntuj muaj kev puas tsuaj thiab kev sib koom tes ib puag ncig.
Nws yuav maj mam dhau los ua qhov tseem ceeb ntawm cov ntaub ntawv fiber.
Lub sijhawm tshaj tawm: Cuaj hlis-26-2022