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 ester, 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 zamaqembu 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 ecwebezelayo. Iningi lokusabela kwe-esterification kanye ne-etherification 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 engavuthiwe ene-reactivity embi ekukhiqizeni i-viscose pulp. Lapho ulungiselela i-viscose (i-cellulose xanthate alkali solution), 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 esihlanjululwe esinomphumela omkhulu wokuvuvukala) noma ukucwilisa ukugaya (ukufakwa okuvamile okuhlangene 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