Cellulose ether ke polymer ea maiketsetso e entsoeng ka selulose ea tlhaho e le thepa e tala ka phetoho ea lik'hemik'hale.Cellulose ether e tsoa ho cellulose ea tlhaho, tlhahiso ea cellulose ether le polymer ea maiketsetso e fapane, thepa ea eona ea mantlha ke selulose, metsoako ea polima ea tlhaho.Ka lebaka la sebopeho sa cellulose ea tlhaho, selulose ka boeona ha e na matla a ho itšoara ka etherifying agent.Empa ka mor'a ho phekoloa ha moemeli oa ho ruruha, maqhama a matla a hydrogen pakeng tsa liketane tsa molek'hule le liketane li ile tsa senyeha, 'me mosebetsi oa sehlopha sa hydroxyl o ile oa lokolloa ka selulose ea alkali e nang le bokhoni ba ho itšoara,' me cellulose ether e ile ea fumanoa ka karabelo ea etherifying agent - sehlopha sa OH ho kena. - KAPA sehlopha.
Thepa ea cellulose ethers e itšetlehile ka mofuta, palo le kabo ea li-substituent.Sehlopha sa cellulose ether se boetse se ipapisitse le mofuta oa li-substituent, tekanyo ea etherification, solubility le ts'ebeliso e amanang le eona e ka aroloa.Ho ea ka mofuta oa li-substituents tsa ketane ea molek'hule, e ka aroloa ka ether e le 'ngoe le ether e tsoakiloeng.MC hangata e sebelisoa joalo ka ether e le 'ngoe, ha HPmc e le ether e tsoakiloeng.Methyl cellulose ether MC ke yuniti ea tsoekere ea cellulose ea tlhaho ho hydroxyl ke methoxide e nkeloa sebaka ke foromo ea sebopeho sa sehlahisoa [CO H7O2 (OH) 3-H (OCH3) H] X, hydroxypropyl methyl cellulose ether HPmc ke yuniti e ho hydroxyl ke karolo. ea methoxide e ile ea nkeloa sebaka, karolo e 'ngoe ea sehlahisoa sa hydroxypropyl se nkeloe sebaka, Sebopeho sa sebopeho ke [C6H7O2 (OH) 3-MN (OCH3) M [OCH2CH (OH) CH3] N] X le hydroxyethyl methyl cellulose ether HEmc, e sebelisoang haholo. le ho rekisoa 'marakeng.
Ho tsoa ho solubility ho ka aroloa ka mofuta oa ionic le mofuta o seng oa ionic.Metsi a qhibilihang a non-ionic cellulose ether haholo-holo a entsoe ka alkyl ether le hydroxyl alkyl ether tse peli tsa mefuta e sa tšoaneng.Ionic Cmc e sebelisoa haholo ho sesepa sa maiketsetso, masela, khatiso, lijo le tšebeliso ea peterole.Non-ionic MC, HPmc, HEmc le tse ling tse sebelisoang haholo ka thepa ea kaho, liaparo tsa latex, meriana, k'hemistri ea letsatsi le letsatsi le likarolo tse ling.Joalo ka motenya, moemeli oa ho boloka metsi, stabilizer, dispersant, moemeli oa ho etsa filimi.
Ho boloka metsi a cellulose ether
Ha ho etsoa thepa ea mohaho, haholo-holo seretse se omeletseng se tsoakiloeng, selulose ether e phetha karolo e ke keng ea nkeloa sebaka, haholo-holo tlhahiso ea seretse se khethehileng (seretse se fetotsoeng), ke karolo ea bohlokoa haholo.
Karolo ea bohlokoa ea selulose e qhibilihang ka metsing ka seretse e na le likarolo tse tharo, e 'ngoe ke bokhoni bo babatsehang ba ho boloka metsi, ea bobeli ke tšusumetso ea ho lumellana ha seretse le thixotropy,' me ea boraro ke ho sebelisana le samente.
Ho boloka metsi a cellulose ether, ho ipapisitse le motheo oa hydroscopicity, sebopeho sa seretse, botenya ba seretse, tlhokahalo ea metsi a seretse, nako ea condensation ea thepa ea condensation.Palo ea metsi ea cellulose ether e tsoa ho solubility le dehydration ea cellulose ether ka boeona.Hoa tsebahala hore liketane tsa limolek'hule tsa cellulose, le hoja li na le palo e kholo ea lihlopha tsa OH tse nang le metsi a mangata, ha li khone ho qhibiliha metsing ka lebaka la sebopeho sa tsona sa kristale e ngata.Bokhoni ba hydration ba lihlopha tsa hydroxyl feela ha boa lekana ho lefella li-intermolecular hydrogen bond le matla a van der Waals.Ha substituents hlahiswa ka ketane ea molek'hule, e seng feela substituents senya ketane ea haedrojene, empa hape le ditlamo interchain hydrogen li robehile ka lebaka la wedging ea substituents pakeng tsa liketane tse haufi.Tse kholoanyane tse nkang sebaka, sebaka se pakeng tsa limolek'hule se seholo.The timetso e kholoanyane ea phello ea hydrogen bond, katoloso ea selulose lattice, tharollo ka har'a selulose ether e fetoha qhibilihang ka metsing, ho thehoa ha tharollo e phahameng ea viscosity.Ha mocheso o ntse o phahama, hydration ea polymer e fokotseha 'me metsi a pakeng tsa liketane a lelekoa.Ha phello ea dehydrating e lekane, limolek'hule li qala ho bokellana 'me gel e phuthoa ka marang-rang a mararo.Lintlha tse amang ho bolokoa ha metsi ka seretse li kenyelletsa cellulose ether viscosity, litekanyetso, botle ba likaroloana le mocheso oa ts'ebeletso.
Ha viscosity e kholo ea cellulose ether, e ntlafatsa ts'ebetso ea ho boloka metsi, le viscosity ea tharollo ea polymer.Boima ba molek'hule (tekanyo ea polymerization) ea polymer e boetse e khethoa ke bolelele le morphology ea sebopeho sa limolek'hule tsa ketane, 'me kabo ea palo ea li-substituent e ama ka ho toba sebaka sa viscosity.[eta] = Km alpha
Intrinsic viscosity ea tharollo ea polymer
M polymer boima ba molek'hule
α polymer tšobotsi kamehla
K viscosity tharollo coefficient
The viscosity ea tharollo ea polymer e itšetlehile ka boima ba limolek'hule tsa polymer.Viscosity le mahloriso a tharollo ea cellulose ether li amana le lits'ebetso tse fapaneng.Ka hona, e 'ngoe le e' ngoe ea cellulose ether e na le litlhaloso tse ngata tse fapaneng tsa viscosity, taolo ea viscosity e boetse e bakoa haholo ke ho senyeha ha selulose ea alkali, e leng ho robeha ha selulose ketane ea limolek'hule ho finyella.
Bakeng sa boholo ba likaroloana, ha karoloana e le ntle, ho boloka metsi ho molemo.Likaroloana tse kholo tsa selulose ether li kopana le metsi, ka holim'a metsi hang-hang li qhibiliha ebe li etsa gel ho phuthela lintho tse bonahalang ho thibela limolek'hule tsa metsi ho tsoela pele ho kenella, ka linako tse ling nako e telele e tsosang takatso e ke ke ea qhalakanngoa ka mokhoa o ts'oanang, ho thehoa ha tharollo ea seretse kapa agglomerate.The solubility ea cellulose ether ke e 'ngoe ea lintlha tsa ho khetha cellulose ether.
Thickening le thixotropy ea cellulose ether
Phello ea bobeli ea cellulose ether - thickening e itšetlehile ka: tekanyo ea cellulose ether polymerization, mahloriso a tharollo, sekhahla sa ho kuta, mocheso le maemo a mang.Thepa ea gelation ea tharollo e ikhethile ho alkyl cellulose le li-derivatives tsa eona tse fetotsoeng.Litšobotsi tsa gelation li amana le tekanyo ea ho fetola, mahloriso a tharollo le li-additives.Bakeng sa li-derivatives tse fetotsoeng tsa hydroxyl alkyl, thepa ea gel e boetse e amana le tekanyo ea phetoho ea hydroxyl alkyl.Bakeng sa tharollo ea mahloriso a tlaase viscosity MC le HPmc ka lokisoa 10% -15% ea mahloriso tharollo, mahareng viscosity MC le HPmc ka lokisoa 5% -10% tharollo le phahameng viscosity MC le HPmc ka feela lokisetsa 2% -3% tharollo, 'me hangata viscosity ea cellulose ether e boetse e graded ke 1% -2% tharollo.Boima bo phahameng ba cellulose ether thickener e sebetsang hantle, motsoako o tšoanang oa tharollo, li-polymers tse fapaneng tsa boima ba molek'hule li na le viscosity e fapaneng, viscosity le boima ba molek'hule li ka hlalosoa ka tsela e latelang, [η] = 2.92 × 10-2 (DPn) 0.905, DPn ke karolelano polymerization tekanyo e phahameng.Low molecular weight cellulose ether ho eketsa ho feta ho finyella sepheo sa viscosity.Viscosity ea eona ha e itšetlehe haholo ka sekhahla sa ho kuta, viscosity e phahameng ho fihlela sepheo sa viscosity, chelete e hlokahalang ho eketsa hanyane, viscosity e itšetlehile ka katleho e ntseng e eketseha.Ka hona, ho finyella ho ts'oana ho itseng, palo e itseng ea cellulose ether (concentration of solution) le viscosity ea tharollo e tlameha ho tiisetsoa.Mocheso oa mocheso oa tharollo o fokotsehile ka mokhoa o ts'oanang le ho eketseha ha motsoako oa tharollo, 'me gelation e etsahetse mocheso oa kamore ka mor'a ho fihla mohopolong o itseng.HPmc e na le mocheso o phahameng oa gelation mocheso oa kamore.
Ho lumellana ho ka boela ha fetoloa ka ho khetha boholo ba likaroloana le li-cellulose ethers tse nang le likhato tse fapaneng tsa phetoho.Seo ho thoeng ke phetoho ke ho kenngoa ha sehlopha sa hydroxyl alkyl ka tekanyo e itseng ea ho fetola sebopeho sa skeleton sa MC.Ka ho fetola litekanyetso tse lekanyelitsoeng tsa phapanyetso ea li-substitute tse peli, ke hore, DS le MS e amanang le phapanyetso ea boleng ba lihlopha tsa methoxy le hydroxyl.Mefuta e fapaneng ea ether ea cellulose e hlokahala ka ho fetola boleng ba mefuta e 'meli ea li-substitute.
kamano pakeng tsa tsitsipano le phetoho.Setšoantšong sa 5, ho eketsoa ha cellulose ether ho ama tšebeliso ea metsi ea seretse 'me ho fetola tekanyo ea metsi-binder ea metsi le samente, e leng phello e teteaneng.Ha tekanyo ea litekanyetso e phahame, ho sebelisoa metsi a mangata.
Li-cellulose ethers tse sebelisoang ka thepa ea mohaho oa phofo li tlameha ho qhibiliha ka potlako metsing a batang le ho fana ka tsamaiso ka mokhoa o nepahetseng.Haeba tekanyo e fanoeng ea ho kuta e ntse e phalla 'me e le colloidal ke sehlahisoa sa boleng bo tlaase kapa se tlaase.
Ho boetse ho na le kamano e ntle pakeng tsa samente slurry consistency le tekanyo ea cellulose ether, cellulose ether e ka eketsa viscosity ea seretse haholo, e kholoanyane lethal dose, le phello e hlakileng haholoanyane.
Cellulose ether aqueous solution e nang le viscosity e phahameng e na le thixotropy e phahameng, e leng e 'ngoe ea litšobotsi tsa cellulose ether.Litharollo tsa metsi tsa mofuta oa Mc polymers hangata li na le pseudoplastic, non-thixotropic fluidity ka tlase ho mocheso oa tsona oa gel, empa thepa ea phallo ea Newtonian ka litheko tse tlase tsa ho kuta.Pseudoplasticity e eketseha ka ho eketseha ha boima ba limolek'hule kapa khatello ea cellulose ether 'me e ikemela ho latela mofuta le degree.Ka hona, li-cellulose ethers tsa sehlopha se tšoanang sa viscosity, ebang ke MC, HPmc kapa HEmc, kamehla li bontša litšobotsi tse tšoanang tsa rheological hafeela mahloriso le mocheso li lula li le teng.Ha mocheso o ntse o eketseha, gel ea mohaho e thehoa 'me phallo e phahameng ea thixotropic e etsahala.Li-cellulose ethers tse nang le mahloriso a phahameng le li-viscosity tse tlaase li bonts'a thixotropy esita le ka tlase ho mocheso oa gel.Thepa ena e na le molemo o moholo kahong ea seretse sa moaho ho lokisa phallo ea eona le thepa e leketlileng.Ho hlokahala hore ho hlalosoe mona hore ho phahama ha viscosity ea cellulose ether, ho boloka metsi ho molemo, empa ho phahama ha viscosity, ho phahamisa boima ba molek'hule ea cellulose ether, ho fokotseha ho lumellanang ha solubility ea eona, e nang le phello e mpe ho mahloriso a seretse le ts'ebetso ea kaho.Ho phahama ha viscosity, ho hlakile haholoanyane phello e teteaneng ea seretse, empa ha se kamano e feletseng ea tekano.Li-viscosity tse ling tse tlase, empa ether ea selulose e fetotsoeng ho ntlafatsa matla a sebopeho sa seretse se metsi se na le ts'ebetso e ntle haholo, ka keketseho ea viscosity, ho boloka metsi a cellulose ether ho ntlafalitsoe.
Nako ea poso: Mar-30-2022