Hom qauv ntawm obcellulose ethersyog muab nyob rau hauv daim duab 1.1 thiab 1.2. Txhua β-D-dehydrated txiv hmab txiv ntoo ntawm cellulose molecule
Chav tsev qab zib (chav rov ua dua ntawm cellulose) yog hloov nrog ib pawg ether txhua ntawm C (2), C (3) thiab C (6) txoj haujlwm, piv txwv li mus txog peb.
ib pawg ether. Vim muaj cov pab pawg hydroxyl, cellulose macromolecules muaj intramolecular thiab intermolecular hydrogen bonds, uas nyuaj rau yaj hauv dej.
Thiab nws yog ib qho nyuaj rau yaj nyob rau hauv yuav luag tag nrho cov organic solvents. Txawm li cas los xij, tom qab etherification ntawm cellulose, ether pawg tau nkag mus rau hauv cov saw molecular,
Nyob rau hauv txoj kev no, hydrogen bonds nyob rau hauv thiab nruab nrab ntawm cov molecules ntawm cellulose raug rhuav tshem, thiab nws cov hydrophilicity kuj tau txhim kho, kom nws solubility tuaj yeem txhim kho.
kho tau zoo heev. Ntawm lawv, Daim duab 1.1 yog cov qauv dav dav ntawm ob chav anhydroglucose ntawm cellulose ether molecular saw, R1-R6 = H
los yog organic hloov. 1.2 yog ib feem ntawm carboxymethyl hydroxyethyl cellulose molecular saw, qhov kev hloov ntawm carboxymethyl yog 0.5,4
Kev hloov qib ntawm hydroxyethyl yog 2.0, thiab qib molar hloov pauv yog 3.0.
Rau txhua qhov hloov pauv ntawm cellulose, tag nrho nws cov etherification tuaj yeem qhia tau raws li qib kev hloov pauv (DS). ua los ntawm fibers
Nws tuaj yeem pom los ntawm cov qauv ntawm cov qauv tseem ceeb uas qhov kev hloov pauv ntawm 0-3. Ntawd yog, txhua chav tsev anhydroglucose nplhaib ntawm cellulose
, qhov nruab nrab tus naj npawb ntawm hydroxyl pawg hloov los ntawm etherifying pawg ntawm tus neeg sawv cev etherifying. Vim yog pawg hydroxyalkyl ntawm cellulose, nws hloov pauv
Lub etherification yuav tsum tau rov pib dua los ntawm pawg tshiab hydroxyl dawb. Yog li ntawd, qhov kev hloov pauv ntawm hom cellulose ether tuaj yeem qhia hauv moles.
degree ntawm kev hloov pauv (MS). Lub npe hu ua molar degree ntawm kev hloov pauv qhia tus nqi ntawm etherifying tus neeg sawv cev ntxiv rau txhua chav anhydroglucose ntawm cellulose.
Qhov nruab nrab loj ntawm cov reactants.
1 General qauv ntawm ib chav tsev glucose
2 Fragments ntawm cellulose ether molecular chains
1.2.2 Kev faib tawm ntawm cellulose ethers
Txawm hais tias cellulose ethers yog ib leeg ethers lossis sib xyaw ethers, lawv cov khoom sib txawv me ntsis. Cellulose macromolecules
Yog tias cov pab pawg hydroxyl ntawm lub nplhaib yog hloov los ntawm ib pawg hydrophilic, cov khoom tuaj yeem muaj qhov qis dua ntawm kev hloov pauv raws li qhov kev hloov pauv qis dua.
Nws muaj qee yam dej solubility; yog tias nws tau hloov los ntawm pawg hydrophobic, cov khoom muaj qee qhov kev hloov pauv tsuas yog thaum qhov kev hloov pauv ntawm qhov nruab nrab.
Cov dej-soluble, tsawg hloov cellulose etherification cov khoom tuaj yeem tsuas yog o hauv dej, lossis yaj hauv cov tshuaj alkali tsawg dua
nruab nrab.
Raws li hom kev hloov pauv, 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 tus, xws li carboxymethyl cellulose, thiab lwm yam. Yog hais tias tus 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 Khoom thiab kev siv ntawm cellulose ethers
Cellulose ether yog ib yam khoom tom qab hloov cellulose etherification, thiab cellulose ether muaj ntau yam tseem ceeb heev. nyiam
Nws muaj cov khoom ua yeeb yaj kiab zoo; Raws li cov ntawv luam tawm, nws muaj cov dej zoo solubility, thickening zog, dej tuav thiab stability;
5
Plain ether tsis muaj ntxhiab, tsis muaj tshuaj lom, thiab muaj biocompatibility zoo. Ntawm lawv, carboxymethyl cellulose (CMC) muaj "kev lag luam monosodium glutamate"
npe.
1.2.3.1 Zaj duab xis tsim
Cov qib ntawm etherification ntawm cellulose ether muaj kev cuam tshuam zoo rau nws cov yeeb yaj kiab tsim cov khoom xws li kev ua yeeb yaj kiab muaj peev xwm thiab kev sib koom ua ke. Cellulose ether
Vim nws lub zog zoo txhua yam thiab zoo sib xws nrog ntau yam resins, nws tuaj yeem siv rau hauv cov yeeb yaj kiab yas, cov nplaum thiab lwm yam ntaub ntawv.
kev npaj khoom siv.
1.2.3.2 Solubility
Vim muaj ntau pawg hydroxyl nyob rau ntawm lub nplhaib ntawm cov pa oxygen uas muaj cov piam thaj, cellulose ethers muaj cov dej solubility zoo dua. thiab
Nyob ntawm seb cov cellulose ether hloov pauv thiab qib ntawm kev hloov pauv, kuj tseem muaj cov kev xaiv sib txawv rau cov kuab tshuaj organic.
1.2.3.3 Thickening
Cellulose ether yog yaj nyob rau hauv aqueous tov nyob rau hauv daim ntawv ntawm colloid, nyob rau hauv lub degree ntawm polymerization ntawm cellulose ether txiav txim lub cellulose.
Viscosity ntawm ether kua. Tsis zoo li Newtonian kua, viscosity ntawm cellulose ether daws hloov nrog shear force, thiab
Vim cov qauv no ntawm cov macromolecules, cov viscosity ntawm cov tshuaj yuav nce sai heev nrog rau cov khoom ntawm cellulose ether, tab sis cov kua viscosity.
Viscosity kuj txo qis sai nrog nce kub [33].
1.2.3.4 Degradability
Cov tshuaj cellulose ether yaj nyob rau hauv dej rau ib lub sij hawm ntawm lub sij hawm yuav loj hlob cov kab mob, yog li tsim cov kab mob enzyme thiab rhuav tshem cov cellulose ether theem.
Qhov uas nyob ib sab unsubstituted glucose unit bonds, yog li txo cov txheeb ze molecular loj ntawm macromolecule. Yog li ntawd, cellulose ethers
Lub preservation ntawm aqueous daws yuav tsum tau ntxiv ib tug npaum li cas ntawm preservatives.
Tsis tas li ntawd, cellulose ethers muaj ntau lwm yam khoom tshwj xeeb xws li kev ua haujlwm saum npoo av, kev ua haujlwm ionic, ua npuas ncauj ruaj khov thiab ntxiv rau.
gel kev. Vim cov khoom no, cellulose ethers yog siv hauv textiles, papermaking, hluavtaws detergents, tshuaj pleev ib ce, zaub mov, tshuaj,
Nws yog dav siv nyob rau hauv ntau lub teb.
1.3 Taw qhia txog cov khoom siv cog qoob loo
Los ntawm cov ntsiab lus ntawm 1.2 cellulose ether, nws tuaj yeem pom tias cov khoom siv raw rau kev npaj ntawm cellulose ether yog paj rwb cellulose, thiab ib qho ntawm cov ntsiab lus ntawm cov ntsiab lus no.
Nws yog siv cellulose muab rho tawm los ntawm cov nroj tsuag raw cov ntaub ntawv los hloov paj rwb cellulose los npaj cellulose ether. Hauv qab no yog cov lus qhia luv luv rau cov nroj tsuag
khoom.
Raws li cov peev txheej xws li roj, thee thiab cov nkev roj tau poob qis, kev txhim kho ntawm ntau yam khoom raws li lawv, xws li cov khoom siv hluavtaws thiab cov yeeb yaj kiab fiber ntau, kuj tseem yuav txwv ntau ntxiv. Nrog rau kev txhim kho txuas ntxiv ntawm zej zog thiab lub teb chaws thoob ntiaj teb (tshwj xeeb tshaj yog
Nws yog ib lub teb chaws tsim kho) uas ua tib zoo saib xyuas qhov teeb meem ntawm ib puag ncig muaj kuab paug. Natural cellulose muaj biodegradability thiab ib puag ncig kev sib koom tes.
Nws yuav maj mam dhau los ua qhov tseem ceeb ntawm cov ntaub ntawv fiber ntau.
Post lub sij hawm: Sep-26-2022