Methylcellulose (MC)
Cov mis molecular ntawm methylcellulose (MC) yog:
[C6H7O2(OH)3-h(OCH3)n\]x
Cov txheej txheem ntau lawm yog ua cellulose ether los ntawm ntau yam kev tshuaj tiv thaiv tom qab cov paj rwb ua kom zoo raug kho nrog alkali, thiab methyl chloride yog siv los ua tus neeg sawv cev etherification. Feem ntau, qib ntawm kev hloov pauv yog 1.6 ~ 2.0, thiab solubility kuj txawv nrog ntau qib ntawm kev hloov pauv. Nws yog rau cov cellulose ether uas tsis yog ionic.
Methylcellulose yaj tau hauv dej txias, thiab nws yuav nyuaj rau yaj hauv dej kub. Nws cov kua dej ruaj khov heev hauv pH = 3 ~ 12.
Nws muaj kev sib raug zoo nrog cov hmoov txhuv nplej siab, cov roj hmab guar, thiab lwm yam thiab ntau yam surfactants. Thaum qhov kub ncav cuag qhov kub gelation, gelation tshwm sim.
Qhov kev khaws cia dej ntawm methylcellulose nyob ntawm nws qhov ntxiv, viscosity, particle fineness thiab dissolving rate.
Feem ntau, yog tias qhov ntxiv ntau, qhov zoo me me, thiab qhov viscosity loj, qhov ceev ntawm kev khaws dej siab. Ntawm lawv, qhov ntau ntawm kev ntxiv muaj qhov cuam tshuam loj tshaj plaws rau qhov ceev ntawm kev khaws dej, thiab qib ntawm viscosity tsis ncaj qha rau qib ntawm kev khaws dej. Qhov ceev ntawm kev yaj feem ntau nyob ntawm qib ntawm kev hloov pauv ntawm qhov chaw ntawm cov cellulose me me thiab qhov zoo ntawm cov khoom me me.
Ntawm cov cellulose ethers saum toj no, methyl cellulose thiab hydroxypropyl methyl cellulose muaj cov dej khaws cia siab dua.
Carboxymethylcellulose (CMC)
Carboxymethyl cellulose, tseem hu ua sodium carboxymethyl cellulose, feem ntau hu ua cellulose, cmc, thiab lwm yam, yog ib qho anionic linear polymer, ib qho sodium ntsev ntawm cellulose carboxylate, thiab yog rov ua dua tshiab thiab tsis muaj qhov kawg. Cov ntaub ntawv raw tshuaj.
Nws yog siv rau hauv kev lag luam ntxuav tes, kev lag luam zaub mov thiab cov roj drilling kua, thiab tus nqi siv hauv cov tshuaj pleev ib ce tsuas yog li 1%.
Ionic cellulose ether yog ua los ntawm cov fibers ntuj (paj rwb, thiab lwm yam) tom qab kev kho alkali, siv sodium monochloroacetate ua tus neeg sawv cev etherification, thiab dhau los ntawm ntau yam kev kho mob tshuaj tiv thaiv.
Feem ntau, qib kev hloov pauv yog 0.4 ~ 1.4, thiab nws cov kev ua tau zoo cuam tshuam loj heev los ntawm qib kev hloov pauv.
CMC muaj peev xwm khi tau zoo heev, thiab nws cov kua dej muaj peev xwm dais tau zoo, tab sis tsis muaj tus nqi hloov pauv yas tiag tiag.
Thaum CMC yaj, qhov tseeb depolymerization tshwm sim. Qhov viscosity pib nce thaum lub sijhawm yaj, dhau mus txog qhov siab tshaj plaws, thiab tom qab ntawd poob rau qhov tiaj tiaj. Qhov viscosity tshwm sim yog cuam tshuam nrog depolymerization.
Qhov degree ntawm depolymerization muaj feem cuam tshuam nrog qhov ntau ntawm cov kuab tshuaj tsis zoo (dej) hauv cov mis. Hauv cov txheej txheem kuab tshuaj tsis zoo, xws li cov tshuaj txhuam hniav uas muaj glycerin thiab dej, CMC yuav tsis depolymerize tag nrho thiab yuav ncav cuag qhov sib npaug.
Yog tias muaj cov dej ntau dhau, CMC uas muaj hydrophilic ntau dua yuav yooj yim dua rau depolymerize dua li CMC uas muaj substituted tsawg.
Hydroxyethylcellulose (HEC)
HEC yog ua los ntawm kev kho cov paj rwb zoo nrog alkali, thiab tom qab ntawd reacting nrog ethylene oxide ua tus neeg sawv cev etherification nyob rau hauv lub xub ntiag ntawm acetone. Qhov degree ntawm kev hloov pauv feem ntau yog 1.5 ~ 2.0. Nws muaj hydrophilicity muaj zog thiab yooj yim rau nqus dej noo.
Hydroxyethyl cellulose yaj tau hauv dej txias, tab sis nws nyuaj rau yaj hauv dej kub. Nws cov kua ruaj khov ntawm qhov kub siab tsis muaj gelling.
Nws ruaj khov rau cov kua qaub thiab cov hauv paus. Cov alkali tuaj yeem ua rau nws yaj sai dua thiab ua rau nws cov viscosity me ntsis. Nws qhov kev tawg hauv dej yog qhov phem dua li ntawm methyl cellulose thiab hydroxypropyl methyl cellulose.
Hydroxypropyl Methyl Cellulose (HPMC)
Cov mis molecular ntawm HPMC yog:
\[C6H7O2(OH)3-mn(OCH3)m,OCH2CH(OH)CH3\]n\]x
Hydroxypropyl methylcellulose yog ib hom cellulose uas nws cov zis thiab kev noj khoom nce ntxiv sai heev.
Nws yog ib qho non-ionic cellulose sib xyaw ether ua los ntawm paj rwb refined tom qab alkalization, siv propylene oxide thiab methyl chloride ua tus neeg sawv cev etherification, los ntawm ntau yam kev tshuaj tiv thaiv. Qib ntawm kev hloov pauv feem ntau yog 1.2 ~ 2.0.
Nws cov khoom sib txawv vim yog qhov sib txawv ntawm cov ntsiab lus methoxyl thiab cov ntsiab lus hydroxypropyl.
Hydroxypropyl methylcellulose yooj yim yaj hauv dej txias, tab sis nws yuav ntsib teeb meem hauv kev yaj hauv dej kub. Tab sis nws qhov kub gelation hauv dej kub siab dua li ntawm methyl cellulose. Qhov solubility hauv dej txias kuj zoo dua piv rau methyl cellulose.
Qhov viscosity ntawm hydroxypropyl methylcellulose muaj feem cuam tshuam nrog nws qhov hnyav molecular, thiab qhov loj dua qhov hnyav molecular, qhov siab dua qhov viscosity. Kub kuj cuam tshuam rau nws qhov viscosity, thaum kub nce, viscosity txo qis. Txawm li cas los xij, nws qhov viscosity siab muaj qhov kub qis dua li methyl cellulose. Nws cov kua ruaj khov thaum khaws cia rau hauv chav tsev kub.
Qhov khaws dej ntawm hydroxypropyl methylcellulose nyob ntawm nws qhov ntxiv, viscosity, thiab lwm yam, thiab nws qhov khaws dej ntawm tib qhov ntxiv yog siab dua li ntawm methyl cellulose.
Hydroxypropyl methylcellulose ruaj khov rau cov kua qaub thiab alkali, thiab nws cov kua dej ruaj khov heev hauv pH = 2 ~ 12. Caustic soda thiab dej txiv qaub tsis muaj feem cuam tshuam rau nws cov kev ua tau zoo, tab sis alkali tuaj yeem ua kom nws cov yaj sai dua thiab ua rau nws cov viscosity nce ntxiv.
Hydroxypropyl methylcellulose ruaj khov rau cov ntsev feem ntau, tab sis thaum qhov concentration ntawm cov ntsev tov siab, qhov viscosity ntawm hydroxypropyl methylcellulose kua feem ntau nce.
Hydroxypropyl methylcellulose tuaj yeem sib xyaw nrog cov polymer sib xyaw uas yaj tau hauv dej los ua cov kua nplaum uas sib xws thiab muaj viscosity siab dua. Xws li polyvinyl cawv, starch ether, zaub gum, thiab lwm yam.
Hydroxypropyl methylcellulose muaj kev tiv thaiv enzyme zoo dua li methylcellulose, thiab nws cov kua tsis tshua muaj peev xwm raug rhuav tshem enzymatically dua li methylcellulose.
Lub sijhawm tshaj tawm: Lub Ob Hlis-14-2023