1.Umgaqo wolwakhiwo kunye nokulungiselela we-cellulose ether
Umfanekiso 1 ubonisa ulwakhiwo oluqhelekileyo lwee-cellulose ethers. Iyunithi nganye ye-bD-anhydroglucose (iyunithi ephindayo ye-cellulose) ithatha indawo yeqela elinye kwiindawo ze-C (2), C (3) kunye ne-C (6), oko kukuthi, kunokuba namaqela e-ether amathathu. Ngenxa yezibopho ze-hydrogen zangaphakathi kunye ne-inter-chain zeiimacromolecule zeselilulose, kunzima ukunyibilika emanzini nakuzo zonke izinyibilikisi zendalo. Ukungeniswa kwamaqela e-ether ngokusebenzisa i-etherification kutshabalalisa iibhondi ze-hydrogen zangaphakathi kunye nezangaphakathi kwe-molecular, kuphucula ukuphilizeka kwayo emanzini, kwaye kuphucula kakhulu ukunyibilika kwayo kwimidiya yamanzi.
Izinto ezisetyenziswa njenge-etherified substituents zizinto eziphantsi kwe-molecular weight alkoxy groups (1 ukuya kwi-4 carbon atom) okanye amaqela e-hydroxyalkyl, anokutshintshwa ngamanye amaqela asebenzayo afana ne-carboxyl, hydroxyl okanye amino groups. Izinto ezisetyenziswa njenge-substituents zinokuba zezinye iintlobo ezahlukeneyo, ezimbini okanye ngaphezulu. Kwi-cellulose macromolecular chain, amaqela e-hydroxyl kwi-C(2), C(3) kunye ne-C(6) kwi-glucose unit nganye atshintshwa ngokwemilinganiselo eyahlukeneyo. Ngokuthe ngqo, i-cellulose ether ngokubanzi ayinaso isakhiwo seekhemikhali esicacileyo, ngaphandle kwezo mveliso zitshintshwa ngokupheleleyo luhlobo olunye lweqela (zonke iindidi ezintathu ze-hydroxyl zitshintshwa). Ezi mveliso zinokusetyenziselwa kuphela uhlalutyo lwelabhoratri kunye nophando, kwaye azinaxabiso lorhwebo.
(a) Ulwakhiwo oluqhelekileyo lweeyunithi ezimbini ze-anhydroglucose ze-cellulose ether molecular chain, i-R1~R6=H, okanye i-organic substituent;
(b) Isiqwenga se-molecular chain se-carboxymethyli-hydroxyethyl cellulose, inqanaba lokutshintshwa kwe-carboxymethyl yi-0.5, inqanaba lokutshintshwa kwe-hydroxyethyl yi-2.0, kwaye inqanaba lokutshintshwa kwe-molar yi-3.0. Olu lwakhiwo lumele inqanaba eliphakathi lokutshintshwa kwamaqela e-etherified, kodwa izinto ezithatha indawo zingaqhelekanga.
Kwinto nganye ethatha indawo, isixa sisonke se-etherification sibonakaliswa liqondo lexabiso le-DS yokutshintsha. Uluhlu lwe-DS yi-0 ~ 3, elilingana nenani eliqhelekileyo lamaqela e-hydroxyl athatyathelwe indawo ngamaqela e-etherification kwiyunithi nganye ye-anhydroglucose.
Kwi-hydroxyalkyl cellulose ethers, i-replacement reaction iya kuqala i-etherification evela kumaqela amatsha e-free hydroxyl, kwaye i-degree of substitution ingalinganiswa ngexabiso le-MS, oko kukuthi, i-molar degree of substitution. Imele inani eliqhelekileyo le-moles ye-etherifying agent reactant eyongeziweyo kwiyunithi nganye ye-anhydroglucose. I-reactant eqhelekileyo yi-ethylene oxide kwaye imveliso ine-hydroxyethyl substituent. KuMfanekiso 1, ixabiso le-MS lemveliso yi-3.0.
Ngokwethiyori, akukho mda uphezulu wexabiso le-MS. Ukuba ixabiso le-DS leqondo lokutshintshwa kwiqela ngalinye leringi yeglucose liyaziwa, ubude obuphakathi betsheyini ye-ether side chainAbanye abavelisi badla ngokusebenzisa i-mass fraction (wt%) yamaqela ahlukeneyo e-etherification (afana ne--OCH3 okanye i--OC2H4OH) ukumela inqanaba kunye nenqanaba lokutshintshwa endaweni yamaxabiso e-DS kunye ne-MS. I-mass fraction yeqela ngalinye kunye nexabiso layo le-DS okanye le-MS linokuguqulwa ngokubala okulula.
Uninzi lwee-ether ze-cellulose zii-polymers ezinyibilikayo emanzini, kwaye ezinye zinyibilika kancinci kwi-organic solvents. I-Cellulose ether ineempawu zokusebenza kakuhle, ixabiso eliphantsi, ukucutshungulwa lula, ubuthi obuphantsi kunye nohlobo olubanzi, kwaye imfuno kunye neendawo zokusetyenziswa zisakhula. Njengearhente encedisayo, i-cellulose ether inamandla amakhulu okusetyenziswa kwiindawo ezahlukeneyo zoshishino. Ingafunyanwa yi-MS/DS.
Ii-ether ze-cellulose zahlulwe ngokwesakhiwo seekhemikhali zezinto ezithatha indawo yazo zibe zii-anionic, cationic kunye nee-nonionic ethers. Ii-ether ze-Nonionic zinokwahlulwa zibe ziimveliso ezinyibilikayo emanzini kunye neemveliso ezinyibilikayo kwioyile.
Iimveliso eziye zaphuhliswa kwimizi-mveliso zidweliswe kwinxalenye ephezulu yeTheyibhile 1. Inxalenye esezantsi yeTheyibhile 1 idwelisa amaqela athile aziwayo e-etherification, angekabi ziimveliso zorhwebo ezibalulekileyo.
Ulandelelwano lwesifinyezo see-ether substituents ezixutyiweyo lunokwabizwa ngokwe-alfabhethi okanye inqanaba le-DS (MS) efanelekileyo, umzekelo, kwi-2-hydroxyethyl methylcellulose, isifinyezo yi-HEMC, kwaye singabhalwa njenge-MHEC ukugqamisa i-methyl substituent.
Amaqela e-hydroxyl kwi-cellulose awafikeleleki lula zii-etherification agents, kwaye inkqubo ye-etherification idla ngokwenziwa phantsi kweemeko ze-alkaline, ngokubanzi kusetyenziswa uxinaniso oluthile lwesisombululo samanzi se-NaOH. I-cellulose yenziwa kuqala ibe yi-alkali cellulose evuvukileyo enesisombululo samanzi se-NaOH, ize emva koko idlule kwi-etherification reaction ene-etherification agent. Ngexesha lokuveliswa nokulungiswa kwee-ethers ezixutyiweyo, iintlobo ezahlukeneyo zee-etherification agents kufuneka zisetyenziswe ngaxeshanye, okanye i-etherification kufuneka yenziwe inyathelo ngenyathelo ngokutya okungapheliyo (ukuba kuyimfuneko). Kukho iintlobo ezine ze-reaction kwi-etherification ye-cellulose, ezishwankathelwe yi-reaction formula (i-cellulosic ithathelwa indawo yi-Cell-OH) ngolu hlobo lulandelayo:
I-equation (1) ichaza i-Williamson etherification reaction. I-RX yi-inorganic acid ester, kwaye i-X yi-halogen Br, Cl okanye i-sulfuric acid ester. I-Chloride R-Cl isetyenziswa kakhulu kumashishini, umzekelo, i-methyl chloride, i-ethyl chloride okanye i-chloroacetic acid. Isixa se-stoichiometric sesiseko siyasetyenziswa kwii-reaction ezinjalo. Iimveliso ze-cellulose ether ze-industrialized methyl cellulose, i-ethyl cellulose kunye ne-carboxymethyl cellulose ziimveliso ze-Williamson etherification reaction.
Ifomula yempendulo (2) yindlela yokongeza ii-epoxides ezisekelwe kwisiseko (ezifana ne-R=H, CH3, okanye i-C2H5) kunye namaqela e-hydroxyl kwiimolekyuli ze-cellulose ngaphandle kokutya isiseko. Le mpendulo isenokuqhubeka njengoko amaqela amatsha e-hydroxyl eveliswa ngexesha lempendulo, nto leyo ekhokelela ekwakhiweni kwee-chain ze-oligoalkylethylene oxide ecaleni: Impendulo efanayo ne-1-aziridine (aziridine) iya kwenza i-aminoethyl ether: I-Cell-O-CH2-CH2-NH2. Iimveliso ezifana ne-hydroxyethyl cellulose, i-hydroxypropyl cellulose kunye ne-hydroxybutyl cellulose zonke ziimveliso ze-epoxidation esekwe kwisiseko.
Ifomula yempendulo (3) yindlela esebenza ngayo i-Cell-OH kunye nee-organic compounds eziqulathe ii-active double bonds kwi-alkaline medium, i-Y liqela elikhupha i-electron, njenge-CN, i-CONH2, okanye i-SO3-Na+. Namhlanje olu hlobo lwempendulo alusetyenziswa rhoqo kwimizi-mveliso.
Ifomula yempendulo (4), i-etherification ene-diazoalkane ayikasetyenziswa njengeshishini okwangoku.
- Iintlobo ze-cellulose ethers
I-cellulose ether inokuba yi-monoether okanye i-ether exutyiweyo, kwaye iimpawu zayo zahlukile. Kukho amaqela e-hydrophilic angaphantsi kwe-substituted kwi-cellulose macromolecule, njengamaqela e-hydroxyethyl, anokunika imveliso inqanaba elithile lokunyibilika kwamanzi, ngelixa kumaqela e-hydrophobic, njenge-methyl, i-ethyl, njl.njl., kuphela ukutshintshwa okuphakathi. Iqondo eliphezulu linokunika imveliso ukunyibilika kwamanzi okuthile, kwaye imveliso engaphantsi kwe-substituted iyanda emanzini okanye inokunyibilika kwisisombululo se-alkali esinyibilikisiweyo. Ngophando olunzulu malunga neempawu ze-cellulose ethers, ii-cellulose ethers ezintsha kunye neendawo zazo zokusetyenziswa ziya kuphuhliswa kwaye ziveliswe rhoqo, kwaye amandla amakhulu okuqhuba yimarike yesicelo ebanzi nehlala icocekile.
Umthetho jikelele wempembelelo yamaqela kwi-mixed ethers kwiimpawu zokunyibilika ngulo:
1) Yongeza umxholo wamaqela angenamanzi kwimveliso ukuze kwandiswe ukungabi namanzi kwe-ether kwaye kwehliswe inqaku lejeli;
2) Yongeza umxholo wamaqela athanda amanzi (njengamaqela e-hydroxyethyl) ukuze kwandiswe inqaku layo lejeli;
3) Iqela le-hydroxypropyl likhethekile, kwaye i-hydroxypropylation efanelekileyo inokunciphisa ubushushu bejeli yemveliso, kwaye ubushushu bejeli bemveliso ephakathi ye-hydroxypropyl buya kunyuka kwakhona, kodwa inqanaba eliphezulu lokutshintshwa liya kunciphisa inqaku layo lejeli; Isizathu sibangelwa bulwakhiwo olukhethekileyo lwe-carbon chain lweqela le-hydroxypropyl, i-hydroxypropylation esezantsi, iibhondi ze-hydrogen ezibuthathaka phakathi kwee-molecules kwi-cellulose macromolecule, kunye namaqela e-hydroxyl aphilic kwii-branch chains. Amanzi anamandla. Kwelinye icala, ukuba utshintsho luphezulu, kuya kubakho i-polymerization kwiqela elisecaleni, umxholo ohambelanayo weqela le-hydroxyl uya kuncipha, i-hydrophobicity iya kwanda, kwaye ukunyibilika kuya kuncipha endaweni yoko.
Imveliso kunye nophando lwei-cellulose etherinembali ende. Ngo-1905, uSuida wabika okokuqala nge-etherification ye-cellulose, eyayine-methylated nge-dimethyl sulfate. Ii-Nonionic alkyl ethers zanikwa ilungelo lobunikazi nguLilienfeld (1912), uDreyfus (1914) kunye noLeuchs (1920) kwii-ethers ze-cellulose ezinyibilikayo emanzini okanye ezinyibilikayo kwi-oyile, ngokulandelelana. UBuchler noGomberg bavelisa i-benzyl cellulose ngo-1921, i-carboxymethyl cellulose yaveliswa okokuqala nguJansen ngo-1918, kwaye uHubert wavelisa i-hydroxyethyl cellulose ngo-1920. Ekuqaleni kweminyaka yoo-1920, i-carboxymethylcellulose yathengiswa eJamani. Ukususela ngo-1937 ukuya ku-1938, imveliso yemizi-mveliso ye-MC kunye ne-HEC yafunyanwa e-United States. ISweden yaqala ukuvelisa i-EHEC enyibilikayo emanzini ngo-1945. Emva ko-1945, imveliso ye-cellulose ether yanda ngokukhawuleza eNtshona Yurophu, e-United States naseJapan. Ekupheleni kowe-1957, iChina CMC yaqala ukuveliswa kwiShanghai Celluloid Factory. Ngowama-2004, amandla emveliso yelizwe lam aya kuba ziitoni ezingama-30,000 ze-ionic ether kunye neetoni ezili-10,000 ze-non-ionic ether. Ngowama-2007, iya kufikelela kwiitoni ezili-100,000 ze-ionic ether kunye neetoni ezingama-40,000 ze-Nonionic ether. Iinkampani zobuchwepheshe ezidibeneyo ekhaya nakwamanye amazwe nazo zihlala zisanda, kwaye amandla emveliso ye-cellulose ether yaseTshayina kunye nenqanaba lobuchwephesha lihlala liphucuka.
Kwiminyaka yakutshanje, ii-cellulose monoethers ezininzi kunye nee-mixed ethers ezinexabiso le-DS ezahlukeneyo, ubungqabavu, ubumsulwa kunye neempawu ze-rheological ziye zaphuhliswa ngokuqhubekayo. Okwangoku, ingqwalasela yophuhliso kwicandelo le-cellulose ethers kukwamkela iteknoloji yemveliso ephucukileyo, iteknoloji yokulungiselela entsha, izixhobo ezintsha, Iimveliso ezintsha, iimveliso ezikumgangatho ophezulu, kunye neemveliso ezicwangcisiweyo kufuneka ziphandwe ngobuchwephesha.
Ixesha leposi: Epreli-28-2024