1.Maumbirwo nepfungwa yekugadzirira cellulose ether
Mufananidzo 1 unoratidza chimiro chakajairika che cellulose ethers. Chikamu chimwe nechimwe che bD-anhydroglucose (chikamu chinodzokorora che cellulose) chinotsiva boka rimwe panzvimbo dze C (2), C (3) uye C (6), kureva kuti, panogona kuva nemapoka matatu e ether. Nekuda kwe intra-chain uye inter-chain hydrogen bonds dzemacromolecules e cellulose, zvakaoma kunyungudika mumvura uye muzvinhu zvinenge zvese zvinonyungudika. Kuunzwa kwemapoka e ether kuburikidza ne etherification kunoparadza hydrogen bonds mukati memamorekuru nepakati pemamorekuru, kunovandudza hydrophilicity yayo, uye kunovandudza zvikuru kunyungudika kwayo mumvura.
Zvinhu zvinotsiva ether zvakajairika imapoka ealkoxy ane huremu hwakaderera (1 kusvika 4 maatomu ekabhoni) kana mapoka ehydroxyalkyl, ayo anogona kutsiviwa nemamwe mapoka anoshanda akadai secarboxyl, hydroxyl kana amino groups. Zvinhu zvinotsiva zvinogona kuva zvemhando imwe, mbiri kana kupfuura dzakasiyana. Pamwe chete ne cellulose macromolecular chain, mapoka ehydroxyl ari panzvimbo dzeC(2), C(3) uye C(6) dzeyuniti yega yega yeglucose anotsiviwa nezvikamu zvakasiyana. Kutaura chokwadi, cellulose ether kazhinji haina chimiro chemakemikari chakajeka, kunze kwezvigadzirwa zvinotsiviwa zvachose nerudzi rumwe rweboka (mapoka ese matatu ehydroxyl anotsiviwa). Zvigadzirwa izvi zvinogona kushandiswa chete pakuongorora nekutsvagisa murabhoritari, uye hazvina kukosha kwekutengeserana.
(a) Maumbirwo akajairika emayuniti maviri e-anhydroglucose e-cellulose ether molecular chain, R1~R6=H, kana chinhu chinotsiva organic;
(b) Chidimbu cheketani yemamorekuru checarboxymethylhydroxyethyl cellulose, mwero wekutsiva carboxymethyl i0.5, mwero wekutsiva hydroxyethyl i2.0, uye mwero wekutsiva molar i3.0. Chimiro ichi chinomiririra avhareji yehuwandu hwekutsiva hwemapoka e etherified, asi zvinotsiva zvacho hazviwanzoitika.
Pachinhu chimwe nechimwe chinotsiva, huwandu hwese hwe etherification hunoratidzwa nedanho rekutsiva DS. Huwandu hweDS i0~3, hwakaenzana neavhareji yehuwandu hwe hydroxyl groups dzakatsiviwa ne etherification groups pa anhydroglucose unit yega yega.
Kune ether dzehydroxyalkyl cellulose, reaction yekutsiva ichatanga etherification kubva kumapoka matsva ehydroxyl akasununguka, uye mwero wekutsiva unogona kuverengerwa neMS value, kureva, molar degree yekutsiva. Inomiririra avhareji yehuwandu hwema moles e etherifying agent reactant inowedzerwa kune imwe neimwe anhydroglucose unit. Reactant yakajairika i ethylene oxide uye chigadzirwa chine hydroxyethyl substituent. MuMufananidzo 1, MS value yechigadzirwa i3.0.
Panyaya yedzidziso, hapana muganho wepamusoro weMS value. Kana DS value yedanho rekutsiva paboka rega rega re glucose ring ichizivikanwa, avhareji yehurefu hwechain ye ether side chain. Vamwe vagadziri vanowanzo shandisawo mass fraction (wt%) yemapoka akasiyana e etherification (akadai se -OCH3 kana -OC2H4OH) kumiririra level uye degree yekutsiva panzvimbo peDS neMS values. Mass fraction yeboka rega rega uye DS kana MS value yayo inogona kushandurwa nekuverenga kuri nyore.
Mazhinji ether e-cellulose mapolymer anonyungudika mumvura, uye mamwe anonyungudikawo zvishoma muzvinhu zvinonyungudika zve organic. Cellulose ether ine hunhu hwekushanda zvakanaka, mutengo wakaderera, nyore kugadzira, chepfu shoma uye mhando dzakasiyana-siyana, uye nzvimbo dzinodiwa uye dzekushandiswa dzichiri kuwedzera. Semubatsiri, cellulose ether ine mukana mukuru wekushandisa munzvimbo dzakasiyana dzeindasitiri. Inogona kuwanikwa neMS/DS.
Maether eCellulose anopatsanurwa zvichienderana nechimiro chemakemikari ezvinotsiva kuita maether eanionic, cationic uye nonionic. Maether eNonionic anogona kukamurwa kuita zvigadzirwa zvinonyungudika mumvura uye zvinonyungudika mumafuta.
Zvigadzirwa zvakambogadzirwa mumaindasitiri zvakanyorwa muchikamu chepamusoro cheTafura 1. Chikamu chezasi cheTafura 1 chinoratidza mamwe mapoka anozivikanwa etherification, ayo asati ava zvigadzirwa zvakakosha zvekutengeserana.
Kurongeka kwezvidimbu zve ether zvakasanganiswa kunogona kutumidzwa zvichienderana nekurongeka kwemavara kana huwandu hweDS (MS) dzakatarwa, semuenzaniso, ye 2-hydroxyethyl methylcellulose, chidimbu chacho ndiHEMC, uye chinogonawo kunyorwa seMHEC kuratidza methyl substituent.
Mapoka ehydroxyl ari pa cellulose haasvikike nyore nyore ne etherification agents, uye maitiro e etherification anowanzoitwa pasi pemamiriro e alkaline, kazhinji achishandisa huwandu hwakati hwe NaOH aqueous solution. Cellulose inotanga kugadzirwa kuita alkali cellulose yakazvimba ne NaOH aqueous solution, uye yozoitwa etherification reaction ne etherification agent. Munguva yekugadzira nekugadzirira mixed ethers, mhando dzakasiyana dze etherification agents dzinofanira kushandiswa panguva imwe chete, kana etherification inofanira kuitwa nhanho nhanho nekudyisa nguva nenguva (kana zvichidikanwa). Kune mhando ina dze reaction mu etherification ye cellulose, idzo dzakapfupikiswa ne reaction formula (cellulosic inotsiviwa ne Cell-OH) seinotevera:
Equation (1) inotsanangura Williamson etherification reaction. RX i inorganic acid ester, uye X i halogen Br, Cl kana sulfuric acid ester. Chloride R-Cl inowanzo shandiswa mumaindasitiri, semuenzaniso, methyl chloride, ethyl chloride kana chloroacetic acid. Huwandu hwe stoichiometric hwebase hunodyiwa muma reaction akadaro. Zvigadzirwa zve ether zve cellulose ether methyl cellulose, ethyl cellulose uye carboxymethyl cellulose zvinogadzirwa ne Williamson etherification reaction.
Fomura yeReaction (2) imhinduro yekuwedzera kwema epoxides ebase-catalyzed (akadai seR=H, CH3, kana C2H5) uye mapoka ehydroxyl pamamorekuru ecellulose asina kudya base. Iyi reaction ingangoramba ichienderera mberi sezvo mapoka matsva ehydroxyl achigadzirwa panguva yereaction, zvichikonzera kuumbwa kwe oligoalkylethylene oxide side chains: Mhinduro yakafanana ne 1-aziridine (aziridine) ichagadzira aminoethyl ether: Cell-O-CH2-CH2-NH2. Zvigadzirwa zvakaita se hydroxyethyl cellulose, hydroxypropyl cellulose uye hydroxybutyl cellulose zvese zvigadzirwa zve base-catalyzed epoxidation.
Fomura yeReaction (3) ndiyo reaction iri pakati peCell-OH neorganic compounds dzine active double bonds mu alkaline medium, Y iboka rinobvisa ma electron, rakadai seCN, CONH2, kana SO3-Na+. Nhasi rudzi urwu rwe reaction haruwanzo shandiswa mumaindasitiri.
Fomura yeReaction (4), etherification ne diazoalkane haisati yagadzirwa.
- Mhando dze ether dze cellulose
Cellulose ether inogona kuva monoether kana mixed ether, uye hunhu hwayo hwakasiyana. Kune mapoka ehydrophilic ane substituted low-substituted pa cellulose macromolecule, akadai se hydroxyethyl groups, anogona kupa chigadzirwa ichi mwero wakati wekunyungudika kwemvura, nepo kune mapoka ehydrophobic, akadai se methyl, ethyl, nezvimwewo, kutsiva kuri pakati nepakati chete Dhigirii repamusoro rinogona kupa chigadzirwa mvura yakati solubility, uye chigadzirwa chine substituted low-substituted chinongozvimba mumvura kana chinogona kunyungudika mu dilute alkali solution. Nekutsvaga kwakadzama pamusoro pehunhu hwe cellulose ethers, cellulose ethers itsva neminda yavo yekushandisa zvicharamba zvichigadzirwa, uye simba guru rinotungamira musika wakakura uye unoramba uchigadziriswa wekushandisa.
Mutemo mukuru wepesvedzero yemapoka mu mixed ethers pahunhu hwekunyungudika ndewekuti:
1) Wedzera huwandu hwemapoka anotya mvura muchigadzirwa kuti uwedzere kushaya mvura kwe ether uye kuderedza poindi ye gel;
2) Wedzera huwandu hwema hydrophilic groups (akadai se hydroxyethyl groups) kuti uwedzere gel point yayo;
3) Boka rehydroxypropyl rakakosha, uye hydroxypropylation yakakodzera inogona kuderedza tembiricha yegel yechigadzirwa, uye tembiricha yegel yechigadzirwa chepakati chehydroxypropyl ichakwira zvakare, asi mwero wepamusoro wekutsiva uchaderedza poindi yayo yegel; Chikonzero ichi imhaka yechimiro chehurefu hwekabhoni cheboka rehydroxypropyl, hydroxypropylation yakaderera, kushomeka kwehydrogen bonds mukati uye pakati pemamorekuru ari mu cellulose macromolecule, uye hydrophilic hydroxyl groups pamacheni ebazi. Mvura ndiyo inonyanya kukosha. Kune rumwe rutivi, kana kutsiva kwacho kwakakwira, pachava nepolymerization paboka reparutivi, huwandu hwehydroxyl group huchaderera, hydrophobicity ichawedzera, uye kunyungudika kuchadzikira pachinzvimbo.
Kugadzirwa nekutsvagisa kweether ye celluloseine nhoroondo refu. Muna 1905, Suida akatanga kutaura nezvekupiswa kweselulosi, iyo yaive nemethylated ne dimethyl sulfate. Nonionic alkyl ethers dzakapihwa patent naLilienfeld (1912), Dreyfus (1914) naLeuchs (1920) ye ethers dzinonyungudika mumvura kana dzinonyungudika mumafuta, zvichiteerana. Buchler naGomberg vakagadzira benzyl cellulose muna 1921, carboxymethyl cellulose yakatanga kugadzirwa naJansen muna 1918, uye Hubert akagadzira hydroxyethyl cellulose muna 1920. Mukutanga kwema1920, carboxymethylcellulose yakatengeswa muGermany. Kubva muna 1937 kusvika 1938, kugadzirwa kwemaindasitiri kweMC neHEC kwakaonekwa muUnited States. Sweden yakatanga kugadzirwa kweEHEC inonyungudika mumvura muna 1945. Mushure ma1945, kugadzirwa kwe ether ye cellulose kwakawedzera nekukurumidza muWestern Europe, United States neJapan. Pakupera kwa1957, China CMC yakatanga kugadzirwa muShanghai Celluloid Factory. Pakazosvika 2004, kugona kwenyika yangu kugadzira zvinhu kwaizova matani 30,000 e-ionic ether uye matani 10,000 e-non-ionic ether. Pakazosvika 2007, yaizosvika matani 100,000 e-ionic ether uye matani 40,000 e-Nonionic ether. Makambani etekinoroji akabatana ari munyika nekune dzimwe nyika ari kuramba achibuda, uye kugona kweChina kugadzira ether ye cellulose uye hunyanzvi zviri kuramba zvichivandudzika.
Mumakore achangopfuura, ma cellulose monoethers akawanda uye ma mixed ethers ane DS values dzakasiyana, viscosities, kuchena uye rheological properties zvave zvichigadzirwa nguva dzose. Parizvino, chinangwa chekuvandudza mumunda we cellulose ethers ndechekushandisa tekinoroji yekugadzira yepamusoro, tekinoroji itsva yekugadzirira, michina mitsva, Zvigadzirwa zvitsva, zvigadzirwa zvemhando yepamusoro, uye zvigadzirwa zvakarongeka zvinofanirwa kuongororwa nehunyanzvi.
Nguva yekutumira: Kubvumbi-28-2024