Okuphuma ku-cellulose kukhiqizwa nge-esterification noma i-etherification yamaqembu e-hydroxyl kuma-polymers e-cellulose anamakhemikhali amakhemikhali.Ngokwezici zesakhiwo semikhiqizo yokusabela, okuphuma ku-cellulose kungahlukaniswa izigaba ezintathu: ama-cellulose ethers, ama-cellulose esters, nama-ester cellulose ether.Ama-cellulose esters asetshenziswa ngempela kwezentengiso yilawa: i-cellulose nitrate, i-cellulose acetate, i-cellulose acetate butyrate ne-cellulose xanthate.Ama-cellulose ether ahlanganisa: i-methyl cellulose, i-carboxymethyl cellulose, i-ethyl cellulose, i-hydroxyethyl cellulose, i-cyanoethyl cellulose, i-hydroxypropyl cellulose ne-hydroxypropyl methyl cellulose.Ngaphezu kwalokho, kukhona okuphuma kokunye okuxubile kwe-ester ether.
Izakhiwo kanye nokusetshenziswa Ngokukhetha ama-reagents afaka esikhundleni kanye nomklamo wenqubo, umkhiqizo ungancibilika emanzini, uncibilikise isixazululo se-alkali noma i-organic solvent, noma ube nezakhiwo ze-thermoplastic, futhi ungasetshenziswa ukwenza imicu yamakhemikhali, amafilimu, izisekelo zefilimu, amapulasitiki, insulating. izinto zokwakha, ukugqoka, i-slurry, i-polymeric dispersant, izithasiselo zokudla kanye nemikhiqizo yansuku zonke yamakhemikhali.Izici zokuphuma kokuphuma ku-cellulose zihlobene nemvelo yezinto ezibambele, idigri ye-DS yamaqembu amathathu e-hydroxyl eqenjini le-glucose eshintshwayo, kanye nokusatshalaliswa kwezinto ezihlukile kuchungechunge lwe-macromolecular.Ngenxa yokungahleliwe kokusabela, ngaphandle komkhiqizo ofakwe endaweni efanayo lapho womathathu amaqembu e-hydroxyl eshintshwa (i-DS ingu-3), kwezinye izimo (ukusabela okulinganayo noma ukusabela okungafani), kutholakala izindawo ezintathu ezihlukile ezilandelayo: Imikhiqizo exutshwe ne Amaqembu e-glucosyl angashintshiwe: ① okufakwe endaweni eyodwa (i-DS ingu-1, C, C noma u-C esikhundleni, ifomula yesakhiwo bona i-cellulose);② okukhishiwe (i-DS ingu-2, C, C, C, C noma C, C izikhundla ziyashintshwa);③ ukufaka esikhundleni okugcwele (i-DS ingu-3).Ngakho-ke, izakhiwo zokuphuma kokunye okuphuma ku-cellulose ezinenani elifanayo lokushintsha zingase zehluke kakhulu.Isibonelo, i-cellulose diacetate efakwe ngokuqondile ku-DS ye-2 ayincibiliki ku-acetone, kodwa i-cellulose diacetate etholwe nge-saponification ye-cellulose triacetate ene-esterified ngokugcwele ingancibilika ngokuphelele ku-acetone.Lokhu kuhlukahluka kokushintshwa kuhlobene nemithetho eyisisekelo ye-cellulose ester nokusabela kwe-etherification.
Umthetho oyisisekelo we-cellulose esterification kanye nokusabela kwe-etherification ku-molecule ye-cellulose, izindawo zokuma kwamaqembu amathathu e-hydroxyl eqenjini le-glucose zihlukile, kanye nomthelela wama-substituent aseduze kanye nesithiyo se-steric nakho kuhlukile.I-acidity ehlobene kanye nezinga lokuhlukaniswa kwamaqembu amathathu e-hydroxyl yilawa: C>C>C.Uma ukusabela kwe-etherification kwenziwa nge-alkaline, iqembu le-C hydroxyl lisabela kuqala, bese kuba yiqembu le-C hydroxyl, bese ekugcineni iqembu le-hydroxyl eliyinhloko.Uma ukusabela kwe-esterification kwenziwa endaweni ene-acidic, ubunzima bokusabela kweqembu ngalinye le-hydroxyl buphambene nokuhlelwa kokusabela kwe-etherification.Uma uphendula nge-reagent eshintshayo enkulu, umphumela wokuvinjwa kwesteric unethonya elibalulekile, futhi iqembu le-C hydroxyl elinomphumela omncane wokuvinjelwa kwesteric kulula ukusabela kunamaqembu e-hydroxyl C kanye no-C.
I-Cellulose iyi-polymer yemvelo ye-crystalline.Iningi le-esterification kanye ne-etherification reactions ukusabela okungafani lapho i-cellulose ihlala iqinile.Isimo sokusabalalisa sama-reagents okusabela ku-fiber cellulose sibizwa ngokuthi ukufinyeleleka.Ukuhlelwa kwe-intermolecular yesifunda se-crystalline kuhlelwe ngokuqinile, futhi i-reagent ingasakazeka kuphela endaweni ye-crystalline.Ukuhlelwa kwe-intermolecular esifundeni se-amorphous kukhululekile, futhi kukhona amaqembu amahhala we-hydroxyl alula ukuxhumana nama-reagents, ngokufinyeleleka okuphezulu nokusabela okulula.Ngokuvamile, izinto zokusetshenziswa ezine-crystallinity ephezulu kanye nosayizi omkhulu wekristalu akulula ukusabela njengezinto ezingavuthiwe ezine-crystallinity ephansi kanye nosayizi omncane wekristalu.Kodwa lokhu akulona iqiniso ngokuphelele, isibonelo, izinga le-acetylation lemicu ye-viscose eyomile ene-crystallinity ephansi kanye ne-crystallinity encane iphansi kakhulu kune-cotton fiber ene-crystallinity ephakeme kanye ne-crystallinity enkulu.Lokhu kungenxa yokuthi amanye amaphoyinti e-hydrogen bonding akhiqizwa phakathi kwama-polymer aseduze phakathi nenqubo yokomisa, okuvimbela ukusabalala kwama-reagents.Uma umswakama ku-cellulose emanzi impahla eluhlaza ithathelwa indawo yi-solvent enkulu ye-organic (njenge-acetic acid, benzene, pyridine) bese yomiswa, ukusebenza kwayo kabusha kuzoba ngcono kakhulu, ngoba ukomisa akukwazi ukuxosha isincibiliki ngokuphelele, kanti okunye Okukhudlwana ama-molecule avaleleke “emigodini” ye-cellulose eluhlaza, akha lokho okubizwa ngokuthi i-cellulose equkethwe.Ibanga eliye lakhuliswa ukuvuvukala akulula ukululama, elivumela ukusakazeka kwama-reagents, futhi likhuthaza izinga lokuphendula kanye nokufana kokusabela.Ngenxa yalesi sizathu, ekukhiqizeni izinto ezihlukahlukene ze-cellulose, kufanele kube nokwelashwa okuhambisanayo kokuvuvukala.Ngokuvamile amanzi, i-asidi noma ingxube ethile yesisombululo se-alkali isetshenziswa njenge-ejenti yokuvuvukala.Ngaphezu kwalokho, ubunzima bokusabela kwamakhemikhali we-pulp yokuqedwa enezinkomba ezifanayo zomzimba namakhemikhali ngokuvamile kuhluke kakhulu, okubangelwa izici ze-morphological zezinhlobo ezihlukahlukene zezitshalo noma amaseli anemisebenzi ehlukene ye-biochemical kanye nesakhiwo esitshalweni esisodwa.kwe.Udonga oluyinhloko longqimba lwangaphandle lwefayibha yezitshalo luvimbela ukungena kwama-reagents futhi lubambezela ukusabela kwamakhemikhali, ngakho-ke ngokuvamile kuyadingeka ukusebenzisa izimo ezihambisanayo enqubweni yokudonsa ukuze kucekelwe phansi udonga oluyisisekelo ukuze kutholwe i-pulp encibilikayo ngokusebenza kabusha okungcono.Isibonelo, i-bagasse pulp iyimpahla eluhlaza enokusabela okubi ekukhiqizeni i-viscose pulp.Lapho ulungiselela i-viscose (isixazululo se-cellulose xanthate alkali), i-carbon disulfide eningi isetshenziswa kune-cotton linter pulp kanye ne-wood pulp.Izinga lokuhlunga liphansi kunalelo le-viscose elilungiselelwe namanye ama-pulp.Lokhu kungenxa yokuthi udonga oluyinhloko lwamangqamuzana e-fiber kamoba alulinyazwanga kahle ngesikhathi sokudonsa kanye nokulungiswa kwe-alkali cellulose ngezindlela ezivamile, okubangele ubunzima ekuphenduleni kokuphuzi.
Imicu ye-alkaline ye-alkaline e-pre-hydrolyzed bagasse pulp fibers] kanye noMfanekiso 2 [imicu ye-bagasse pulp ngemva kokufakwa kwe-alkali] yizithombe zokuskena ngesibonakhulu se-electron ebusweni bemicu ye-bagasse pulp ngemva kwenqubo ye-alkaline yangaphambi kwe-hydrolyzed kanye nokufakwa kwe-alkaline evamile ngokulandelana, ezokuqala zisabonakala imigodi ecacile;ekugcineni, nakuba imigodi inyamalala ngenxa yokuvuvukala kwesisombululo se-alkali, udonga oluyinhloko lusahlanganisa yonke i-fiber.Uma "ukufakelwa kwesibili" (ukufakwa okuvamile okulandelwa ukufakwa kwesibili ngesisombululo se-alkali esixutshwe nomphumela omkhulu wokuvuvukala) noma ukugaya-ukugaya (inqubo yokufaka okuvamile ehlangene nokugaya ngomshini), ukusabela okuphuzi kungaqhubeka kahle, izinga lokuhlunga kwe-viscose. ithuthukiswa kakhulu.Lokhu kungenxa yokuthi zombili lezi zindlela ezimbili ezingenhla zingakwazi ukuxebula odongeni oluyinhloko, ziveze ungqimba lwangaphakathi lokusabela okulula, okulungele ukungena kwama-reagents futhi kuthuthukise ukusebenza kokusabela (Fig. 3 [Ukufakwa kwesibili kwe-bagasse pulp fiber. ], Fig. Ukugaya i-Bagasse Pulp Fibers]).
Eminyakeni yamuva nje, kuye kwavela izinhlelo zokuncibilikisa ezingenamanzi ezingahlakaza ngokuqondile i-cellulose.Okufana ne-dimethylformamide ne-NO, i-dimethyl sulfoxide ne-paraformaldehyde, nezinye izincibilikisi ezixubile, njll., zivumela i-cellulose ukuthi ibhekane nokusabela okulinganayo.Nokho, eminye yale mithetho eshiwo ngenhla yokusabela okungaphandle kwesigaba ayisasebenzi.Isibonelo, lapho ulungiselela i-cellulose diacetate encibilika ku-acetone, akudingekile ukuba kwenziwe i-hydrolysis ye-cellulose triacetate, kodwa ingafakwa ngokuqondile i-esterified kuze kube yilapho i-DS isingu-2.
Isikhathi sokuthumela: Feb-27-2023