1.Structure ndi kukonzekera mfundo ya cellulose ether
Chithunzi 1 chikuwonetsa mawonekedwe a cellulose ethers. Gawo lililonse la bD-anhydroglucose (gawo lobwerezabwereza la cellulose) limalowa m'malo mwa gulu limodzi pamalo a C (2), C (3) ndi C (6), ndiye kuti, pangakhale magulu atatu a ether. Chifukwa cha ma intra-chain and inter-chain chain hydrogen bond ofcellulose macromolecules, ndizovuta kusungunula m'madzi komanso pafupifupi zosungunulira zonse za organic. Kuyamba kwa magulu a ether kudzera mu etherification kumawononga ma intramolecular ndi intermolecular hydrogen bonds, kumapangitsa kuti hydrophilicity yake ikhale yabwino, komanso kumapangitsanso kusungunuka kwake m'madzi.
Ma etherified etherified ndi magulu ochepera a molekyulu a alkoxy (1 mpaka 4 maatomu a kaboni) kapena magulu a hydroxyalkyl, omwe amatha kulowetsedwa ndi magulu ena ogwira ntchito monga magulu a carboxyl, hydroxyl kapena amino. Zolowa m'malo zitha kukhala zamtundu umodzi, ziwiri kapena zingapo zosiyana. Pamagulu a cellulose macromolecular, magulu a hydroxyl omwe ali pa C(2), C(3) ndi C(6) pagawo lililonse la shuga amalowetsedwa m'malo osiyanasiyana. Kunena zowona, ether ya cellulose nthawi zambiri ilibe kapangidwe kake ka mankhwala, kupatulapo zinthu zomwe zimalowetsedwa m'malo ndi gulu limodzi (magulu onse atatu a hydroxyl amalowetsedwa m'malo). Zogulitsazi zitha kugwiritsidwa ntchito posanthula ma labotale ndi kafukufuku, ndipo zilibe phindu lamalonda.
(a) Kapangidwe kake ka mayunitsi awiri a anhydroglucose a cellulose ether molecular chain, R1~R6=H, kapena cholowa mmalo mwa organic;
(b) Chidutswa cha molekyulu cha carboxymethylhydroxyethyl cellulose, digiri ya m'malo mwa carboxymethyl ndi 0.5, digiri ya hydroxyethyl ndi 2.0, ndi digiri ya m'malo mwa molar ndi 3.0. Kapangidwe kameneka kakuyimira mulingo wolowa m'malo wamagulu a etherified, koma olowa m'malo amakhala mwachisawawa.
Pa cholowa chilichonse, kuchuluka kwa etherification kumawonetsedwa ndi kuchuluka kwa DS mtengo. Mtundu wa DS ndi 0 ~ 3, womwe ndi wofanana ndi avareji yamagulu a hydroxyl osinthidwa ndi magulu a etherification pagawo lililonse la anhydroglucose.
Pakuti hydroxyalkyl mapadi ethers, m'malo anachita adzayamba etherification ku magulu atsopano ufulu hydroxyl, ndi mlingo wa m'malo akhoza quantified ndi MS mtengo, ndiko kuti, mlingo molar wa m'malo. Imayimira kuchuluka kwa timamolekyu ta etherifying agent reactant yomwe imawonjezeredwa pagawo lililonse la anhydroglucose. Reactant wamba ndi ethylene oxide ndipo mankhwalawo amakhala ndi hydroxyethyl m'malo. Pa chithunzi 1, mtengo wa MS wa chinthucho ndi 3.0.
Mwachidziwitso, palibe malire apamwamba a mtengo wa MS. Ngati mtengo wa DS wa kuchuluka kwa kulowetsa m'malo pagulu lililonse la mphete ya glucose umadziwika, pafupifupi kutalika kwa unyolo wa mbali ya etherOpanga ena nthawi zambiri amagwiritsa ntchito gawo lalikulu (wt%) lamagulu osiyanasiyana ophatikiza (monga -OCH3 kapena -OC2H4OH) kuyimira gawo lolowa m'malo ndi digiri m'malo mwa DS ndi MS. Gawo lalikulu la gulu lirilonse ndi mtengo wake wa DS kapena MS ukhoza kusinthidwa ndi kuwerengera kosavuta.
Ma cellulose ether ambiri ndi ma polima osungunuka m'madzi, ndipo ena amasungunuka pang'ono mu zosungunulira za organic. Cellulose ether ali ndi makhalidwe a dzuwa kwambiri, mtengo wotsika, processing zosavuta, otsika kawopsedwe ndi zosiyanasiyana, ndi kufunika ndi ntchito minda akadali kukula. Monga wothandizira wothandizira, cellulose ether ali ndi kuthekera kwakukulu kogwiritsa ntchito m'magawo osiyanasiyana amakampani. angapezeke ndi MS/DS.
Ma cellulose ether amagawidwa molingana ndi kapangidwe kake kazinthu zomwe zimasinthidwa kukhala anionic, cationic ndi nonionic ethers. Ma ether a Nonionic amatha kugawidwa m'madzi osungunuka ndi mafuta osungunuka.
Zogulitsa zomwe zakhala zikuchulukirachulukira zalembedwa kumtunda kwa Table 1. Gawo lapansi la Gulu 1 limatchula magulu ena odziwika a etherification, omwe sanakhalebe zinthu zofunika kwambiri zamalonda.
Dongosolo lachidule la olowa m'malo osakanikirana a ether amatha kutchulidwa motsatira ma alfabeti kapena mulingo wa DS (MS), mwachitsanzo, 2-hydroxyethyl methylcellulose, chidule chake ndi HEMC, ndipo itha kulembedwanso ngati MHEC ku onetsani cholowa cha methyl.
Magulu a hydroxyl pa cellulose sapezeka mosavuta ndi othandizira a etherification, ndipo njira yopangira etherification nthawi zambiri imachitika m'mikhalidwe yamchere, makamaka pogwiritsa ntchito ndende ya NaOH yamadzimadzi. Ma cellulose amayamba kupangidwa kukhala cellulose yotupa ya alkali yokhala ndi yankho lamadzi la NaOH, kenako ndikuchita etherification ndi etherification wothandizira. Pakupanga ndi kukonza ma ether osakanikirana, mitundu yosiyanasiyana ya ma etherification iyenera kugwiritsidwa ntchito nthawi imodzi, kapena etherification iyenera kuchitidwa pang'onopang'ono ndikudyetsa kwapakatikati (ngati kuli kofunikira). Pali zinayi anachita mitundu mu etherification wa mapadi, amene mwachidule ndi chilinganizo anachita (cellulosic m'malo ndi Cell-OH) motere:
Equation (1) imafotokoza momwe Williamson etherification amachitira. RX ndi inorganic acid ester, ndipo X ndi halogen Br, Cl kapena sulfuric acid ester. Chloride R-Cl nthawi zambiri amagwiritsidwa ntchito m'makampani, mwachitsanzo, methyl chloride, ethyl chloride kapena chloroacetic acid. Kuchuluka kwa stoichiometric kwa maziko kumadyedwa muzochita zotere. Mafakitale opangidwa ndi cellulose ether methyl cellulose, ethyl cellulose ndi carboxymethyl cellulose ndizomwe zimapangidwa ndi Williamson etherification reaction.
Rection formula (2) ndikuwonjezera kwa ma epoxides a base-catalyzed (monga R=H, CH3, kapena C2H5) ndi magulu a hydroxyl pa mamolekyu a cellulose popanda kuwononga maziko. Izi zikuyenera kupitilira pamene magulu atsopano a hydroxyl amapangidwa panthawiyi, zomwe zimapangitsa kuti pakhale unyolo wa oligoalkylethylene oxide side: Zomwe zimachitika ndi 1-aziridine (aziridine) zidzapanga aminoethyl ether: Cell-O-CH2-CH2-NH2 . Zogulitsa monga hydroxyethyl cellulose, hydroxypropyl cellulose ndi hydroxybutyl cellulose zonse ndizinthu zopangidwa ndi base-catalyzed epoxidation.
Rection formula (3) ndi zomwe zimachitika pakati pa Cell-OH ndi organic compounds zomwe zimakhala ndi zomangira ziwiri zogwira ntchito mu alkaline medium, Y ndi gulu lochotsa ma elekitironi, monga CN, CONH2, kapena SO3-Na+. Masiku ano machitidwe amtunduwu sagwiritsidwa ntchito kawirikawiri m'mafakitale.
Rection formula (4), etherification ndi diazoalkane sichinapangidwebe mafakitale panobe.
- Mitundu ya ma cellulose ethers
Cellulose ether ikhoza kukhala monoether kapena ether yosakanikirana, ndipo katundu wake ndi wosiyana. Pali otsika m'malo hydrophilic magulu pa mapadi macromolecule, monga magulu hydroxyethyl, amene angathe endow mankhwala ndi mlingo wina wa solubility madzi, pamene magulu hydrophobic, monga methyl, ethyl, etc., kokha zolimbitsa m'malo High digiri akhoza perekani mankhwalawa kuti asungunuke m'madzi ena, ndipo chotsitsa chochepa cholowa m'malo chimangotupa m'madzi kapena chimatha kusungunuka mumadzimadzi amchere. Ndi kafukufuku wozama pazabwino za ma cellulose ethers, ma cellulose ether atsopano ndi magawo awo ogwiritsira ntchito azipangidwa mosalekeza ndikupangidwa, ndipo mphamvu yayikulu kwambiri ndi msika wotakata komanso woyengedwa mosalekeza.
Lamulo lachiwopsezo chamagulu mu ethers wosakanikirana pa zinthu zosungunuka ndi:
1) Kuchulukitsa zomwe zili m'magulu a hydrophobic muzogulitsa kuti muwonjezere hydrophobicity ya ether ndikutsitsa gel;
2) Wonjezerani zomwe zili m'magulu a hydrophilic (monga magulu a hydroxyethyl) kuti muwonjezere gel osakaniza;
3) Gulu la hydroxypropyl ndi lapadera, ndipo hydroxypropylation yoyenera imatha kuchepetsa kutentha kwa gel osakaniza, ndipo kutentha kwa gel osakaniza kwa sing'anga hydroxypropylated mankhwala adzauka kachiwiri, koma mlingo wapamwamba m'malo adzachepetsa gel osakaniza; Chifukwa ndi chifukwa chapadera mpweya unyolo kutalika dongosolo la hydroxypropyl gulu, otsika mlingo hydroxypropylation, wofooka zomangira haidrojeni ndi pakati mamolekyu mu mapadi macromolecule, ndi magulu hydrophilic hydroxyl pa nthambi unyolo. Madzi ndi amene amalamulira. Komano, ngati m'malo ndi mkulu, padzakhala polymerization pa mbali gulu, zili wachibale wa gulu hydroxyl adzachepa, ndi hydrophobicity adzawonjezeka, ndi solubility adzakhala kuchepetsedwa m'malo.
Kupanga ndi kafukufuku wacellulose etherili ndi mbiri yakale. Mu 1905, Suida adalengeza koyamba za etherification ya cellulose, yomwe inali methylated ndi dimethyl sulfate. Ma Nonionic alkyl ethers anali ovomerezeka ndi Lilienfeld (1912), Dreyfus (1914) ndi Leuchs (1920) amadzi osungunuka kapena osungunuka a cellulose ethers, motsatana. Buchler ndi Gomberg anapanga benzyl cellulose mu 1921, carboxymethyl cellulose inayamba kupangidwa ndi Jansen mu 1918, ndipo Hubert anapanga hydroxyethyl cellulose mu 1920. Kumayambiriro kwa zaka za m'ma 1920, carboxymethylcellulose inkagulitsidwa ku Germany. Kuyambira 1937 mpaka 1938, kupanga mafakitale a MC ndi HEC kudachitika ku United States. Sweden anayamba kupanga madzi sungunuka EHEC mu 1945. Pambuyo 1945, kupanga mapadi etero kukodzedwa mofulumira ku Western Europe, United States ndi Japan. Kumapeto kwa 1957, China CMC idayamba kupangidwa ku Shanghai Celluloid Factory. Pofika m’chaka cha 2004, mphamvu yopangira dziko langa idzakhala matani 30,000 a ionic ether ndi matani 10,000 a ether omwe si a ionic. Pofika chaka cha 2007, idzafika matani 100,000 a ionic ether ndi matani 40,000 a Nonionic ether. Olowa makampani luso kunyumba ndi kunja komanso mosalekeza akutuluka, ndi China mapalo etere mphamvu kupanga ndi mlingo luso nthawi zonse kusintha.
M'zaka zaposachedwa, ma cellulose monoethers ambiri ndi ma ether osakanikirana okhala ndi ma DS osiyanasiyana, ma viscosities, chiyero ndi ma rheological apangidwa mosalekeza. Pakalipano, cholinga cha chitukuko m'munda wa ma cellulose ethers ndikutengera luso lazopangapanga, ukadaulo watsopano wokonzekera, zida zatsopano, Zatsopano, zinthu zamtengo wapatali, ndi zinthu mwadongosolo ziyenera kufufuzidwa mwaukadaulo.
Nthawi yotumiza: Apr-28-2024