Cellulose ethers yog ntau yam dej-soluble polymers muab tau los ntawm cellulose, ib tug natural polymer pom nyob rau hauv cov nroj tsuag cell phab ntsa. Cov ethers no muaj cov khoom tshwj xeeb xws li thickening, stabilization, film-forming, thiab dej tuav, thiab yog dav siv nyob rau hauv ntau yam lag luam xws li tshuaj, zaub mov, tshuaj pleev ib ce, thiab kev tsim kho. Ntawm cov cellulose ethers, hydroxyethyl cellulose (HEC) thiab hydroxypropyl methylcellulose (HPMC) yog ob qho tseem ceeb derivatives, txhua tus muaj cov khoom sib txawv thiab kev siv.
1. Taw qhia txog cellulose ethers
A. Cellulose Structure thiab Derivatives
Txheej txheem cej luam ntawm cellulose:
Cellulose yog ib hom kab hluav taws xob uas muaj cov piam thaj sib txuas los ntawm β-1,4-glycosidic bonds.
Nws yog nplua nuj nyob rau hauv cov nroj tsuag cell phab ntsa thiab muab cov qauv kev txhawb nqa thiab rigidity rau cov ntaub so ntswg.
Cellulose ether derivatives:
Cellulose ethers yog muab los ntawm cellulose los ntawm kev hloov tshuaj lom neeg.
Ethers tau qhia kom nce solubility thiab hloov cov khoom ua haujlwm.
2. Hydroxyethylcellulose (HEC)
A. Cov qauv thiab kev sib txuas
Chemical structure:
HEC yog tau los ntawm etherification ntawm cellulose nrog ethylene oxide.
Hydroxyethyl pawg hloov cov pawg hydroxyl hauv cov qauv cellulose.
Degree ntawm kev hloov pauv (DS):
DS hais txog qhov nruab nrab ntawm cov pawg hydroxyethyl ib chav tsev anhydroglucose.
Nws cuam tshuam rau solubility, viscosity thiab lwm yam khoom ntawm HEC.
B. Xwm
Solubility:
HEC yog soluble nyob rau hauv ob qho tib si dej txias thiab kub, muab kev yooj yim ntawm daim ntawv thov.
viscosity:
Raws li kev hloov kho rheology, nws cuam tshuam rau lub thickness thiab ntws ntawm cov tshuaj.
Nws txawv nrog DS, concentration thiab kub.
Zaj duab xis tsim:
Ua ib zaj duab xis pob tshab nrog adhesion zoo heev.
C. Daim ntawv thov
tshuaj:
Siv raws li ib tug thickener nyob rau hauv cov ntaub ntawv ua kua.
Txhim kho lub viscosity thiab stability ntawm qhov muag tee.
Paints thiab Coatings:
Txhim kho viscosity thiab muab cov khoom zoo heev thickening.
Txhim kho xim adhesion thiab stability.
Cov khoom siv tu tus kheej:
Pom muaj nyob rau hauv cov tshuaj zawv plaub hau, cream thiab tshuaj pleev ib ce ua lub thickener thiab stabilizer.
Muab kev ntxhib los mos rau cov tshuaj pleev ib ce.
3. Hydroxypropylmethylcellulose (HPMC)
A. Cov qauv thiab kev sib txuas
Chemical structure:
HPMC yog tsim los ntawm kev hloov cov pab pawg hydroxyl nrog methoxy thiab hydroxypropyl pawg.
Etherification tshwm sim los ntawm cov tshuaj tiv thaiv nrog propylene oxide thiab methyl chloride.
Kev hloov pauv Methoxy thiab hydroxypropyl:
Cov pab pawg methoxy pab txhawb kev solubility, thaum pawg hydroxypropyl cuam tshuam rau viscosity.
B. Xwm
Thermal gelation:
Exhibits reversible thermal gelation, tsim gels ntawm qhov kub thiab txias.
Yuav siv tau rau kev tswj kev tso tshuaj tshuaj npaj.
Kev tuav dej:
Cov dej tuav tau zoo heev, ua rau nws tsim nyog rau kev tsim kho.
Kev ua haujlwm saum npoo:
Tso tawm cov khoom zoo li surfactant los pab kom ruaj khov emulsions.
C. Daim ntawv thov
Kev tsim kho kev lag luam:
Siv los ua tus neeg saib xyuas dej hauv cov cement-based mortar.
Txhim kho kev ua haujlwm thiab adhesion ntawm pobzeb adhesives.
tshuaj:
Feem ntau siv nyob rau hauv qhov ncauj thiab tshuaj pleev ib ce npaj.
Yooj yim tswj cov tshuaj tso tawm vim nws lub peev xwm gel-forming.
kev lag luam zaub mov:
Ua raws li cov thickener thiab stabilizer hauv cov khoom noj.
Muab cov kev ntxhib los mos thiab qhov ncauj zoo dua hauv qee qhov kev siv.
4. Kev soj ntsuam sib piv
A. Qhov sib txawv ntawm kev sib xyaw
HEC thiab HPMC synthesis:
HEC yog tsim los ntawm reacting cellulose nrog ethylene oxide.
HPMC synthesis suav nrog ob qhov kev hloov pauv ntawm methoxy thiab hydroxypropyl pawg.
B. Kev ua tau zoo sib txawv
Solubility thiab viscosity:
HEC yog soluble hauv dej txias thiab kub, thaum lub solubility ntawm HPMC cuam tshuam los ntawm methoxy pawg ntsiab lus.
HEC feem ntau pom cov viscosity qis dua piv rau HPMC.
Gel cwj pwm:
Tsis zoo li HPMC, uas tsim cov gels thim rov qab, HEC tsis raug thermal gelation.
C. Qhov txawv ntawm daim ntawv thov
Kev tuav dej:
HPMC yog qhov zoo dua rau kev tsim kho daim ntawv thov vim nws cov dej tuav tau zoo heev.
Film forming peev xwm:
HEC tsim cov yeeb yaj kiab uas muaj qhov zoo adhesion, ua rau nws haum rau qee yam kev siv uas tsim cov yeeb yaj kiab yog qhov tseem ceeb.
5 Kev xaus
Hauv cov ntsiab lus, hydroxyethyl cellulose (HEC) thiab hydroxypropyl methylcellulose (HPMC) yog cov cellulose ethers tseem ceeb nrog cov khoom tshwj xeeb thiab kev siv. Lawv cov qauv tshuaj tshwj xeeb, cov txheej txheem ntawm kev sib txuas, thiab cov khoom siv ua haujlwm ua rau lawv muaj ntau yam hauv ntau yam lag luam. Kev nkag siab txog qhov sib txawv ntawm HEC thiab HPMC tuaj yeem pab koj txiav txim siab zoo thaum xaiv cov cellulose ether txoj cai rau ib daim ntawv thov tshwj xeeb, txawm nyob rau hauv cov chaw muag tshuaj, kev tsim kho, pleev xim lossis cov khoom tu tus kheej. Raws li kev siv thev naus laus zis nrog kev tshawb fawb, kev tshawb fawb ntxiv yuav nthuav tawm ntau daim ntawv thov thiab kev hloov kho, yog li txhim kho cov txiaj ntsig ntawm cov cellulose ethers hauv ntau qhov chaw.
Lub sij hawm xa tuaj: Dec-11-2023