1.Sebopeho le molao-motheo oa ho lokisa oa ether ea selulose
Setšoantšo sa 1 se bontša sebopeho se tloaelehileng sa li-ether tsa cellulose. Yuniti e 'ngoe le e 'ngoe ea bD-anhydroglucose (yuniti e pheta-phetoang ea cellulose) e nkela sehlopha se le seng sebaka maemong a C (2), C (3) le C (6), ke hore, ho ka ba le lihlopha tse tharo tsa ether. Ka lebaka la litlamo tsa haedrojene tsa kahare ho ketane le lipakeng tsa ketane ealimolek'hule tsa cellulose, ho thata ho qhibilihisa ka metsing le hoo e batlang e le metsoako eohle ea lintho tse phelang. Ho kenngoa ha lihlopha tsa ether ka ho kopanya ether ho senya maqhama a haedrojene ka hare ho limolek'hule le ka hare ho limolek'hule, ho ntlafatsa philicity ea eona ea metsi, 'me ho ntlafatsa haholo ho qhibiliha ha eona mecheng ea metsi.
Lintho tse tloaelehileng tse nkeloang sebaka ke lihlopha tsa alkoxy tse boima bo tlase ba limolek'hule (liathomo tsa khabone tse 1 ho isa ho tse 4) kapa lihlopha tsa hydroxyalkyl, tse ka nkeloang sebaka ke lihlopha tse ling tse sebetsang joalo ka lihlopha tsa carboxyl, hydroxyl kapa amino. Lintho tse nkeloang sebaka e ka ba tsa mofuta o le mong, e 'meli kapa ho feta tse fapaneng. Holim'a ketane ea macromolecular ea cellulose, lihlopha tsa hydroxyl maemong a C(2), C(3) le C(6) a yuniti ka 'ngoe ea glucose li nkeloa sebaka ka litekanyo tse fapaneng. Ha e le hantle, cellulose ether ka kakaretso ha e na sebopeho se tobileng sa lik'hemik'hale, ntle le lihlahisoa tse nkeloang sebaka ka botlalo ke mofuta o le mong oa sehlopha (lihlopha tsohle tse tharo tsa hydroxyl li nkeloa sebaka). Lihlahisoa tsena li ka sebelisoa feela bakeng sa tlhahlobo le lipatlisiso tsa laboratori, 'me ha li na boleng ba khoebo.
(a) Sebopeho se akaretsang sa diyuniti tse pedi tsa anhydroglucose tsa ketane ya dimolek'hule ya ether ya cellulose, R1~R6=H, kapa ntho e nkelang sebaka sa tlhaho sebaka;
(b) Karoloana ea ketane ea limolek'hule ea carboxymethylhydroxyethyl cellulose, tekanyo ea ho nkeloa sebaka ha carboxymethyl ke 0.5, tekanyo ea ho nkeloa sebaka ha hydroxyethyl ke 2.0, 'me tekanyo ea ho nkeloa sebaka ha molar ke 3.0. Sebopeho sena se emela boemo bo tloaelehileng ba ho nkeloa sebaka ha lihlopha tse nang le ether, empa lintho tse nkeloang sebaka ha e le hantle li sa reroa.
Bakeng sa ntho e 'ngoe le e 'ngoe e nkelang sebaka, kakaretso ea etherification e bontšoa ke tekanyo ea boleng ba DS bo nkeloang sebaka. Mefuta ea DS ke 0 ~ 3, e leng palo e lekanang le karolelano ea lihlopha tsa hydroxyl tse nkeloang sebaka ke lihlopha tsa etherification yuniti ka 'ngoe ea anhydroglucose.
Bakeng sa li-ether tsa hydroxyalkyl cellulose, karabelo ea phetisetso e tla qala ho fetoha ha ether ho tsoa lihlopheng tse ncha tsa hydroxyl tse lokolohileng, 'me tekanyo ea phetisetso e ka lekanngoa ka boleng ba MS, ke hore, tekanyo ea molar ea phetisetso. E emela palo e tloaelehileng ea li-moles tsa reactant ea moemeli ea etherifying e ekelitsoeng ho yuniti e 'ngoe le e 'ngoe ea anhydroglucose. Reactant e tloaelehileng ke ethylene oxide 'me sehlahisoa se na le sebaka sa hydroxyethyl. Setšoantšong sa 1, boleng ba MS ba sehlahisoa ke 3.0.
Ka khopolo-taba, ha ho na moedi o ka hodimo bakeng sa boleng ba MS. Haeba boleng ba DS ba tekanyo ya phetolo sehlopheng se seng le se seng sa lesale la glucose bo tsejwa, bolelele ba ketane bo tloaelehileng ba ketane ya lehlakore la ether Bahlahisi ba bang le bona hangata ba sebedisa karolo ya boima (wt%) ya dihlopha tse fapaneng tsa etherification (tse kang -OCH3 kapa -OC2H4OH) ho emela boemo le tekanyo ya phetolo ho ena le boleng ba DS le MS. Karolo ya boima ya sehlopha se seng le se seng le boleng ba sona ba DS kapa MS di ka fetolwa ka ho bala ho bonolo.
Bongata ba li-ether tsa cellulose ke li-polymer tse qhibilihang ka metsing, 'me tse ling li boetse li qhibiliha ka karolo e itseng ka har'a li-solvent tsa tlhaho. Cellulose ether e na le litšobotsi tsa bokhoni bo phahameng, theko e tlase, ts'ebetso e bonolo, chefo e tlase le mefuta e mengata, 'me masimo a tlhoko le ts'ebeliso a ntse a atoloha. Joaloka moemeli ea thusang, ether ea cellulose e na le bokhoni bo boholo ba ts'ebeliso masimong a fapaneng a indasteri. e ka fumanoa ke MS/DS.
Li-ether tsa cellulose li aroloa ho latela sebopeho sa lik'hemik'hale tsa lintho tse nkeloang sebaka ke li-ether tsa anionic, cationic le nonionic. Li-ether tse seng tsa ionic li ka aroloa ka lihlahisoa tse qhibilihang metsing le tse qhibilihang ka oli.
Lihlahisoa tse seng li entsoe indastering li thathamisitsoe karolong e ka holimo ea Tafole ea 1. Karolo e ka tlase ea Tafole ea 1 e thathamisa lihlopha tse ling tse tsejoang tsa etherification, tse e-so fetohe lihlahisoa tsa bohlokoa tsa khoebo.
Tatellano ea khutsufatso ea li-substituent tse tsoakiloeng tsa ether e ka rehoa ho latela tatellano ea alfabeta kapa boemo ba DS (MS) e amehang, mohlala, bakeng sa 2-hydroxyethyl methylcellulose, khutsufatso ke HEMC, 'me e ka boela ea ngoloa e le MHEC ho totobatsa substituent ea methyl.
Lihlopha tsa hydroxyl tse holim'a cellulose ha li fumanehe habonolo ke li-etherification agents, 'me ts'ebetso ea etherification hangata e etsoa tlas'a maemo a alkaline, ka kakaretso ho sebelisoa motsoako o itseng oa tharollo ea metsi ea NaOH. Cellulose e etsoa pele ho ba alkaline cellulose e ruruhileng ka tharollo ea metsi ea NaOH, ebe e feta karabelong ea etherification ka etherification agent. Nakong ea tlhahiso le ho lokisoa ha li-ethers tse tsoakiloeng, mefuta e fapaneng ea li-etherification agents e lokela ho sebelisoa ka nako e le 'ngoe, kapa etherification e lokela ho etsoa mohato ka mohato ka ho fepa nako le nako (haeba ho hlokahala). Ho na le mefuta e mene ea karabelo ho etherification ea cellulose, e akaretsoang ke foromo ea karabelo (cellulosic e nkeloa sebaka ke Cell-OH) ka tsela e latelang:
Equation (1) e hlalosa karabelo ea Williamson etherification. RX ke ester ea asiti e sa tloaelehang, 'me X ke halogen Br, Cl kapa sulfuric acid ester. Chloride R-Cl hangata e sebelisoa indastering, mohlala, methyl chloride, ethyl chloride kapa chloroacetic acid. Palo ea stoichiometric ea motheo e sebelisoa liketsong tse joalo. Lihlahisoa tsa ether tsa cellulose tse entsoeng indastering methyl cellulose, ethyl cellulose le carboxymethyl cellulose ke lihlahisoa tsa karabelo ea etherification ea Williamson.
Foromo ea karabelo (2) ke karabelo ea tlatsetso ea li-epoxide tse kentsoeng motheong (tse kang R=H, CH3, kapa C2H5) le lihlopha tsa hydroxyl limolek'huleng tsa cellulose ntle le ho ja motheo. Karabelo ena e kanna ea tsoela pele ha lihlopha tse ncha tsa hydroxyl li hlahisoa nakong ea karabelo, e leng se lebisang ho thehoeng ha liketane tsa lehlakore tsa oligoalkylethylene oxide: Karabelo e tšoanang le 1-aziridine (aziridine) e tla theha aminoethyl ether: Cell-O-CH2-CH2-NH2. Lihlahisoa tse kang hydroxyethyl cellulose, hydroxypropyl cellulose le hydroxybutyl cellulose kaofela ke lihlahisoa tsa epoxidation e entsoeng motheong.
Foromo ea karabelo (3) ke karabelo pakeng tsa Cell-OH le metsoako ea lintho tse phelang e nang le litlamo tse peli tse sebetsang sebakeng sa alkaline, Y ke sehlopha se hulang lielektrone, joalo ka CN, CONH2, kapa SO3-Na+. Kajeno mofuta ona oa karabelo ha o sebelisoe hangata indastering.
Foromo ea karabelo (4), etherification ka diazoalkane ha e so ka e etsoa indasteri.
- Mefuta ea li-ether tsa cellulose
Ether ea cellulose e ka ba monoether kapa ether e tsoakiloeng, 'me thepa ea eona ea fapana. Ho na le lihlopha tsa hydrophilic tse nketsoeng sebaka ka tlase ho cellulose macromolecule, joalo ka lihlopha tsa hydroxyethyl, tse ka fang sehlahisoa tekanyo e itseng ea ho qhibiliha ha metsi, ha bakeng sa lihlopha tse sa nkeheng sebaka, joalo ka methyl, ethyl, jj., ke phetoho e itekanetseng feela. Tekanyo e phahameng e ka fa sehlahisoa ho qhibiliha ho itseng ha metsi, 'me sehlahisoa se nketsoeng sebaka ka tlase se kokomoha feela ka metsing kapa se ka qhibiliha ka tharollo ea alkali e hlapolotsoeng. Ka lipatlisiso tse tebileng mabapi le thepa ea li-ether tsa cellulose, li-ether tse ncha tsa cellulose le masimo a tsona a ts'ebeliso li tla ntlafatsoa le ho hlahisoa khafetsa, 'me matla a maholohali a ho khanna ke' maraka o pharaletseng le o ntlafalitsoeng o tsoelang pele.
Molao o akaretsang oa tšusumetso ea lihlopha tse nang le li-ether tse tsoakiloeng holim'a thepa ea ho qhibiliha ke:
1) Eketsa dikahare tsa dihlopha tse sa rateng metsi sehlahisweng ho eketsa ho sa rateng metsi ha ether le ho theola ntlha ya gel;
2) Eketsa dikahare tsa dihlopha tse phelang metsing (tse kang dihlopha tsa hydroxyethyl) ho eketsa ntlha ya yona ya gel;
3) Sehlopha sa hydroxypropyl se ikhetha, 'me hydroxypropylation e nepahetseng e ka fokotsa mocheso oa gel oa sehlahisoa, 'me mocheso oa gel oa sehlahisoa se mahareng sa hydroxypropyl o tla nyoloha hape, empa boemo bo phahameng ba ho nkeloa sebaka bo tla fokotsa ntlha ea eona ea gel; Lebaka ke ka lebaka la sebopeho se khethehileng sa bolelele ba ketane ea carbon sa sehlopha sa hydroxypropyl, hydroxypropylation ea boemo bo tlase, litlamo tse fokolang tsa hydrogen ka har'a le pakeng tsa limolek'hule tse ka har'a cellulose macromolecule, le lihlopha tsa hydroxyl tse phelang ka metsing liketane tsa makala. Metsi aa busa. Ka lehlakoreng le leng, haeba phetoho e le holimo, ho tla ba le polymerization sehlopheng se ka thoko, litaba tse amanang le sehlopha sa hydroxyl li tla fokotseha, hydrophobicity e tla eketseha, 'me ho qhibiliha ho tla fokotseha ho e-na le hoo.
Tlhahiso le lipatlisiso tsaether ea selulosee na le nalane e telele. Ka 1905, Suida o ile a tlaleha ka lekhetlo la pele ka ho fetoha ha cellulose, e neng e na le methylated ka dimethyl sulfate. Li-ether tsa alkyl tse seng tsa ionic li ile tsa fuoa patente ke Lilienfeld (1912), Dreyfus (1914) le Leuchs (1920) bakeng sa li-ether tsa cellulose tse qhibilihang ka metsing kapa tse qhibilihang ka oli, ka ho latellana. Buchler le Gomberg ba hlahisitse benzyl cellulose ka 1921, carboxymethyl cellulose e ile ea hlahisoa ka lekhetlo la pele ke Jansen ka 1918, 'me Hubert a hlahisa hydroxyethyl cellulose ka 1920. Mathoasong a lilemo tsa bo-1920, carboxymethylcellulose e ile ea rekisoa Jeremane. Ho tloha ka 1937 ho isa ho 1938, tlhahiso ea indasteri ea MC le HEC e ile ea etsoa United States. Sweden e qalile tlhahiso ea EHEC e qhibilihang ka metsing ka 1945. Kamora 1945, tlhahiso ea ether ea cellulose e ile ea atoloha ka potlako Europe Bophirimela, United States le Japane. Qetellong ea 1957, China CMC e ile ea qala ho hlahisoa Fekthering ea Celluloid ea Shanghai. Ka 2004, bokhoni ba tlhahiso ea naha ea heso e tla ba lithane tse 30,000 tsa ionic ether le lithane tse 10,000 tsa non-ionic ether. Ka 2007, e tla fihla lithane tse 100,000 tsa ionic ether le lithane tse 40,000 tsa Non-ionic ether. Likhamphani tsa theknoloji tse kopaneng lapeng le kantle ho naha le tsona li ntse li hlaha khafetsa, 'me bokhoni ba tlhahiso ea cellulose ether ea Chaena le boemo ba tekheniki li ntse li ntlafala khafetsa.
Lilemong tsa morao tjena, li-monoether tse ngata tsa cellulose le li-ether tse tsoakiloeng tse nang le boleng bo fapaneng ba DS, viscosities, bohloeki le thepa ea rheological li 'nile tsa ntlafatsoa ka ho tsoelang pele. Hona joale, sepheo sa nts'etsopele lefapheng la li-ether tsa cellulose ke ho amohela theknoloji e tsoetseng pele ea tlhahiso, theknoloji e ncha ea ho lokisa, lisebelisoa tse ncha, Lihlahisoa tse ncha, lihlahisoa tsa boleng bo holimo, le lihlahisoa tse hlophisitsoeng li lokela ho etsoa lipatlisiso tsa tekheniki.
Nako ea poso: Mmesa-28-2024