Methylcellulose (MC)
Fomula ya molekyulu ya methylcellulose (MC) ndi iyi:
[C6H7O2(OH)3-h(OCH3)n\]x
Njira yopangira ndi kupanga cellulose ether kudzera muzochita zingapo pambuyo poti thonje loyengedwa lakonzedwa ndi alkali, ndipo methyl chloride imagwiritsidwa ntchito ngati etherification agent. Kawirikawiri, mlingo wa kusintha ndi 1.6 ~ 2.0, ndipo kusungunuka kumasiyananso ndi madigiri osiyanasiyana a kusintha. Ndi ya non-ionic cellulose ether.
Methylcellulose imasungunuka m'madzi ozizira, ndipo zimakhala zovuta kusungunuka m'madzi otentha. Madzi ake ndi olimba kwambiri pa pH = 3 ~ 12.
Imagwirizana bwino ndi starch, guar gum, ndi zina zotero. Ndi ma surfactants ambiri. Kutentha kukafika pa kutentha kwa gelation, gelation imachitika.
Kusungidwa kwa madzi kwa methylcellulose kumadalira kuchuluka kwake, kukhuthala kwake, kusalala kwa tinthu tating'onoting'ono, ndi kuchuluka kwa kusungunuka kwake.
Kawirikawiri, ngati kuchuluka kwa zowonjezera kuli kwakukulu, kupyapyala kumakhala kochepa, ndipo kukhuthala kumakhala kwakukulu, kuchuluka kwa madzi kumakhala kwakukulu. Pakati pawo, kuchuluka kwa zowonjezera kumakhudza kwambiri kuchuluka kwa madzi, ndipo kuchuluka kwa kukhuthala sikufanana mwachindunji ndi kuchuluka kwa madzi. Kuchuluka kwa kusungunuka kumadalira makamaka kuchuluka kwa kusintha kwa pamwamba pa tinthu ta cellulose ndi kupyapyala kwa tinthu.
Pakati pa ma ether a cellulose omwe ali pamwambapa, methyl cellulose ndi hydroxypropyl methyl cellulose ali ndi kuchuluka kwa madzi osungira.
Carboxymethylcellulose (CMC)
Carboxymethyl cellulose, yomwe imadziwikanso kuti sodium carboxymethyl cellulose, yomwe imadziwikanso kuti cellulose, cmc, ndi zina zotero, ndi anionic linear polymer, sodium salt ya cellulose carboxylate, ndipo imapangidwanso komanso yosatha. Zipangizo zopangira mankhwala.
Amagwiritsidwa ntchito makamaka m'makampani opanga sopo, mafakitale azakudya ndi mafuta obowola, ndipo kuchuluka komwe kumagwiritsidwa ntchito mu zodzoladzola ndi pafupifupi 1%.
Ionic cellulose ether imapangidwa kuchokera ku ulusi wachilengedwe (thonje, ndi zina zotero) pambuyo pochiza ndi alkali, pogwiritsa ntchito sodium monochloroacetate ngati etherification, ndikuchita chithandizo chamankhwala osiyanasiyana.
Mlingo wa kusintha nthawi zambiri umakhala 0.4 ~ 1.4, ndipo magwiridwe antchito ake amakhudzidwa kwambiri ndi kuchuluka kwa kusintha.
CMC ili ndi luso lomangirira bwino, ndipo yankho lake lamadzi lili ndi luso labwino loyimitsa, koma palibe phindu lenileni la kusintha kwa pulasitiki.
Pamene CMC isungunuka, kusungunuka kwa polymer kumachitikadi. Kusungunuka kumayamba kukwera panthawi yosungunuka, kudutsa pamlingo wapamwamba, kenako kumatsika mpaka pamwamba. Kusungunuka komwe kumachitika kumagwirizana ndi kusungunuka kwa polymer.
Mlingo wa depolymerization umagwirizana kwambiri ndi kuchuluka kwa solvent (madzi) yofooka mu kapangidwe kake. Mu dongosolo losauka la solvent, monga mankhwala otsukira mano okhala ndi glycerin ndi madzi, CMC sidzachepa kwathunthu ndipo idzafika pamlingo woyenera.
Pankhani ya kuchuluka kwa madzi, CMC yomwe imalowa m'malo mwa madzi imakhala yosavuta kuichotsa polima kuposa CMC yomwe imalowa m'malo mwa madzi ochepa.
Hydroxyethylcellulose (HEC)
HEC imapangidwa popaka thonje loyengedwa ndi alkali, kenako n’kuchitapo kanthu ndi ethylene oxide ngati etherification ngati pali acetone. Mlingo wa kusintha nthawi zambiri umakhala 1.5 ~ 2.0. Ili ndi hydrophilicity yamphamvu ndipo imayamwa mosavuta chinyezi.
Hydroxyethyl cellulose imasungunuka m'madzi ozizira, koma imakhala yovuta kusungunuka m'madzi otentha. Yankho lake limakhala lokhazikika kutentha kwambiri popanda kusungunuka.
Ndi yokhazikika ku ma acid ndi ma bases wamba. Alkalis imatha kufulumizitsa kusungunuka kwake ndikuwonjezera kukhuthala kwake pang'ono. Kufalikira kwake m'madzi ndikoipa pang'ono kuposa kwa methyl cellulose ndi hydroxypropyl methyl cellulose.
Hydroxypropyl Methyl Cellulose (HPMC)
Fomula ya molekyulu ya HPMC ndi iyi:
\[C6H7O2(OH)3-mn(OCH3)m,OCH2CH(OH)CH3\]n\]x
Hydroxypropyl methylcellulose ndi mtundu wa cellulose womwe ntchito yake ndi kugwiritsidwa ntchito kwake zikuwonjezeka mofulumira.
Ndi ether yosakanikirana ya cellulose yosakhala ionic yopangidwa kuchokera ku thonje loyengedwa bwino pambuyo pa alkalization, pogwiritsa ntchito propylene oxide ndi methyl chloride ngati etherification, kudzera muzochita zingapo. Mlingo wa kusintha nthawi zambiri umakhala 1.2 ~ 2.0.
Kapangidwe kake ndi kosiyana chifukwa cha kusiyana kwa kuchuluka kwa methoxyl ndi kuchuluka kwa hydroxypropyl.
Hydroxypropyl methylcellulose imasungunuka mosavuta m'madzi ozizira, koma imakumana ndi zovuta kusungunuka m'madzi otentha. Koma kutentha kwake kwa gelation m'madzi otentha ndi kwakukulu kwambiri kuposa kwa methyl cellulose. Kusungunuka m'madzi ozizira nakonso kumawonjezeka kwambiri poyerekeza ndi methyl cellulose.
Kukhuthala kwa hydroxypropyl methylcellulose kumagwirizana ndi kulemera kwake kwa mamolekyulu, ndipo kulemera kwa mamolekyulu kukakhala kwakukulu, kukhuthala kumawonjezeka. Kutentha kumakhudzanso kukhuthala kwake, pamene kutentha kukukwera, kukhuthala kumachepa. Komabe, kukhuthala kwake kwakukulu kumakhala ndi kutentha kochepa kuposa methyl cellulose. Yankho lake limakhala lokhazikika likasungidwa kutentha kwa chipinda.
Kusunga madzi kwa hydroxypropyl methylcellulose kumadalira kuchuluka kwake kowonjezera, kukhuthala kwake, ndi zina zotero, ndipo kuchuluka kwake kosungira madzi pa kuchuluka komweko kowonjezerako kumakhala kwakukulu kuposa kwa methyl cellulose.
Hydroxypropyl methylcellulose ndi yokhazikika ku asidi ndi alkali, ndipo yankho lake lamadzi ndi lokhazikika kwambiri pa pH = 2 ~ 12. Caustic soda ndi madzi a laimu sizikhudza kwambiri magwiridwe ake, koma alkali imatha kufulumizitsa kusungunuka kwake ndikuwonjezera kukhuthala kwake.
Hydroxypropyl methylcellulose imakhala yokhazikika ku mchere wamba, koma pamene mchere uli wambiri, kukhuthala kwa hydroxypropyl methylcellulose kumawonjezeka.
Hydroxypropyl methylcellulose ikhoza kusakanikirana ndi mankhwala a polymer osungunuka m'madzi kuti apange yankho lofanana komanso lokhuthala kwambiri. Monga polyvinyl alcohol, starch ether, vegetable gum, ndi zina zotero.
Hydroxypropyl methylcellulose ili ndi kukana bwino kwa ma enzyme kuposa methylcellulose, ndipo yankho lake silingathe kuwonongeka ndi ma enzyme kuposa methylcellulose.
Nthawi yotumizira: Feb-14-2023